| 1 | |
| 2 | |
| 3 | * linux/kernel/fork.c
|
| 4 | *
|
| 5 | * Copyright (C) 1991, 1992 Linus Torvalds
|
| 6 |
|
| 7 |
|
| 8 | |
| 9 | * 'fork.c' contains the help-routines for the 'fork' system call
|
| 10 | * (see also entry.S and others).
|
| 11 | * Fork is rather simple, once you get the hang of it, but the memory
|
| 12 | * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
|
| 13 |
|
| 14 |
|
| 15 | #include <linux/anon_inodes.h>
|
| 16 | #include <linux/slab.h>
|
| 17 | #include <linux/sched/autogroup.h>
|
| 18 | #include <linux/sched/mm.h>
|
| 19 | #include <linux/sched/coredump.h>
|
| 20 | #include <linux/sched/user.h>
|
| 21 | #include <linux/sched/numa_balancing.h>
|
| 22 | #include <linux/sched/stat.h>
|
| 23 | #include <linux/sched/task.h>
|
| 24 | #include <linux/sched/task_stack.h>
|
| 25 | #include <linux/sched/cputime.h>
|
| 26 | #include <linux/seq_file.h>
|
| 27 | #include <linux/rtmutex.h>
|
| 28 | #include <linux/init.h>
|
| 29 | #include <linux/unistd.h>
|
| 30 | #include <linux/module.h>
|
| 31 | #include <linux/vmalloc.h>
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| 32 | #include <linux/completion.h>
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| 33 | #include <linux/personality.h>
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| 34 | #include <linux/mempolicy.h>
|
| 35 | #include <linux/sem.h>
|
| 36 | #include <linux/file.h>
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| 37 | #include <linux/fdtable.h>
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| 38 | #include <linux/iocontext.h>
|
| 39 | #include <linux/key.h>
|
| 40 | #include <linux/kmsan.h>
|
| 41 | #include <linux/binfmts.h>
|
| 42 | #include <linux/mman.h>
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| 43 | #include <linux/mmu_notifier.h>
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| 44 | #include <linux/fs.h>
|
| 45 | #include <linux/mm.h>
|
| 46 | #include <linux/mm_inline.h>
|
| 47 | #include <linux/nsproxy.h>
|
| 48 | #include <linux/capability.h>
|
| 49 | #include <linux/cpu.h>
|
| 50 | #include <linux/cgroup.h>
|
| 51 | #include <linux/security.h>
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| 52 | #include <linux/hugetlb.h>
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| 53 | #include <linux/seccomp.h>
|
| 54 | #include <linux/swap.h>
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| 55 | #include <linux/syscalls.h>
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| 56 | #include <linux/jiffies.h>
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| 57 | #include <linux/futex.h>
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| 58 | #include <linux/compat.h>
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| 59 | #include <linux/kthread.h>
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| 60 | #include <linux/task_io_accounting_ops.h>
|
| 61 | #include <linux/rcupdate.h>
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| 62 | #include <linux/ptrace.h>
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| 63 | #include <linux/mount.h>
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| 64 | #include <linux/audit.h>
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| 65 | #include <linux/memcontrol.h>
|
| 66 | #include <linux/ftrace.h>
|
| 67 | #include <linux/proc_fs.h>
|
| 68 | #include <linux/profile.h>
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| 69 | #include <linux/rmap.h>
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| 70 | #include <linux/ksm.h>
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| 71 | #include <linux/acct.h>
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| 72 | #include <linux/userfaultfd_k.h>
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| 73 | #include <linux/tsacct_kern.h>
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| 74 | #include <linux/cn_proc.h>
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| 75 | #include <linux/freezer.h>
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| 76 | #include <linux/delayacct.h>
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| 77 | #include <linux/taskstats_kern.h>
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| 78 | #include <linux/tty.h>
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| 79 | #include <linux/fs_struct.h>
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| 80 | #include <linux/magic.h>
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| 81 | #include <linux/perf_event.h>
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| 82 | #include <linux/posix-timers.h>
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| 83 | #include <linux/user-return-notifier.h>
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| 84 | #include <linux/oom.h>
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| 85 | #include <linux/khugepaged.h>
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| 86 | #include <linux/signalfd.h>
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| 87 | #include <linux/uprobes.h>
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| 88 | #include <linux/aio.h>
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| 89 | #include <linux/compiler.h>
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| 90 | #include <linux/sysctl.h>
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| 91 | #include <linux/kcov.h>
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| 92 | #include <linux/livepatch.h>
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| 93 | #include <linux/thread_info.h>
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| 94 | #include <linux/stackleak.h>
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| 95 | #include <linux/kasan.h>
|
| 96 | #include <linux/scs.h>
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| 97 | #include <linux/io_uring.h>
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| 98 | #include <linux/bpf.h>
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| 99 | #include <linux/stackprotector.h>
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| 100 | #include <linux/user_events.h>
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| 101 | #include <linux/iommu.h>
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| 102 |
|
| 103 | #include <asm/pgalloc.h>
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| 104 | #include <linux/uaccess.h>
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| 105 | #include <asm/mmu_context.h>
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| 106 | #include <asm/cacheflush.h>
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| 107 | #include <asm/tlbflush.h>
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| 108 |
|
| 109 | #include <trace/events/sched.h>
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| 110 |
|
| 111 | #define CREATE_TRACE_POINTS
|
| 112 | #include <trace/events/task.h>
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| 113 |
|
| 114 | |
| 115 | * Minimum number of threads to boot the kernel
|
| 116 |
|
| 117 | #define MIN_THREADS 20
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| 118 |
|
| 119 | |
| 120 | * Maximum number of threads
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| 121 |
|
| 122 | #define MAX_THREADS FUTEX_TID_MASK
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| 123 |
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| 124 | |
| 125 | * Protected counters by write_lock_irq(&tasklist_lock)
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| 126 |
|
| 127 | unsigned long total_forks;
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| 128 | int nr_threads;
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| 129 |
|
| 130 | static int max_threads;
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| 131 |
|
| 132 | #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
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| 133 |
|
| 134 | static const char * const resident_page_types[] = {
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| 135 | NAMED_ARRAY_INDEX(MM_FILEPAGES),
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| 136 | NAMED_ARRAY_INDEX(MM_ANONPAGES),
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| 137 | NAMED_ARRAY_INDEX(MM_SWAPENTS),
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| 138 | NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
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| 139 | };
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| 140 |
|
| 141 | DEFINE_PER_CPU(unsigned long, process_counts) = 0;
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| 142 |
|
| 143 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock);
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| 144 |
|
| 145 | #ifdef CONFIG_PROVE_RCU
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| 146 | int lockdep_tasklist_lock_is_held(void)
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| 147 | {
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| 148 | return lockdep_is_held(&tasklist_lock);
|
| 149 | }
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| 150 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
|
| 151 | #endif
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| 152 |
|
| 153 | int nr_processes(void)
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| 154 | {
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| 155 | int cpu;
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| 156 | int total = 0;
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| 157 |
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| 158 | for_each_possible_cpu(cpu)
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| 159 | total += per_cpu(process_counts, cpu);
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| 160 |
|
| 161 | return total;
|
| 162 | }
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| 163 |
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| 164 | void __weak arch_release_task_struct(struct task_struct *tsk)
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| 165 | {
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| 166 | }
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| 167 |
|
| 168 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
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| 169 | static struct kmem_cache *task_struct_cachep;
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| 170 |
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| 171 | static inline struct task_struct *alloc_task_struct_node(int node)
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| 172 | {
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| 173 | return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
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| 174 | }
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| 175 |
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| 176 | static inline void free_task_struct(struct task_struct *tsk)
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| 177 | {
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| 178 | kmem_cache_free(task_struct_cachep, tsk);
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| 179 | }
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| 180 | #endif
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| 181 |
|
| 182 | #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
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| 183 |
|
| 184 | |
| 185 | * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
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| 186 | * kmemcache based allocator.
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| 187 |
|
| 188 | # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
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| 189 |
|
| 190 | # ifdef CONFIG_VMAP_STACK
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| 191 | |
| 192 | * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
|
| 193 | * flush. Try to minimize the number of calls by caching stacks.
|
| 194 |
|
| 195 | #define NR_CACHED_STACKS 2
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| 196 | static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
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| 197 |
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| 198 | struct vm_stack {
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| 199 | struct rcu_head rcu;
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| 200 | struct vm_struct *stack_vm_area;
|
| 201 | };
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| 202 |
|
| 203 | static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
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| 204 | {
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| 205 | unsigned int i;
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| 206 |
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| 207 | for (i = 0; i < NR_CACHED_STACKS; i++) {
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| 208 | if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
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| 209 | continue;
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| 210 | return true;
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| 211 | }
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| 212 | return false;
|
| 213 | }
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| 214 |
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| 215 | static void thread_stack_free_rcu(struct rcu_head *rh)
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| 216 | {
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| 217 | struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
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| 218 |
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| 219 | if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
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| 220 | return;
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| 221 |
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| 222 | vfree(vm_stack);
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| 223 | }
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| 224 |
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| 225 | static void thread_stack_delayed_free(struct task_struct *tsk)
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| 226 | {
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| 227 | struct vm_stack *vm_stack = tsk->stack;
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| 228 |
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| 229 | vm_stack->stack_vm_area = tsk->stack_vm_area;
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| 230 | call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
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| 231 | }
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| 232 |
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| 233 | static int free_vm_stack_cache(unsigned int cpu)
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| 234 | {
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| 235 | struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
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| 236 | int i;
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| 237 |
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| 238 | for (i = 0; i < NR_CACHED_STACKS; i++) {
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| 239 | struct vm_struct *vm_stack = cached_vm_stacks[i];
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| 240 |
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| 241 | if (!vm_stack)
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| 242 | continue;
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| 243 |
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| 244 | vfree(vm_stack->addr);
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| 245 | cached_vm_stacks[i] = NULL;
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| 246 | }
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| 247 |
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| 248 | return 0;
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| 249 | }
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| 250 |
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| 251 | static int memcg_charge_kernel_stack(struct vm_struct *vm)
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| 252 | {
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| 253 | int i;
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| 254 | int ret;
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| 255 | int nr_charged = 0;
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| 256 |
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| 257 | BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
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| 258 |
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| 259 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
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| 260 | ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
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| 261 | if (ret)
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| 262 | goto err;
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| 263 | nr_charged++;
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| 264 | }
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| 265 | return 0;
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| 266 | err:
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| 267 | for (i = 0; i < nr_charged; i++)
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| 268 | memcg_kmem_uncharge_page(vm->pages[i], 0);
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| 269 | return ret;
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| 270 | }
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| 271 |
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| 272 | static int alloc_thread_stack_node(struct task_struct *tsk, int node)
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| 273 | {
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| 274 | struct vm_struct *vm;
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| 275 | void *stack;
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| 276 | int i;
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| 277 |
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| 278 | for (i = 0; i < NR_CACHED_STACKS; i++) {
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| 279 | struct vm_struct *s;
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| 280 |
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| 281 | s = this_cpu_xchg(cached_stacks[i], NULL);
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| 282 |
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| 283 | if (!s)
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| 284 | continue;
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| 285 |
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| 286 |
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| 287 | kasan_unpoison_range(s->addr, THREAD_SIZE);
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| 288 |
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| 289 | stack = kasan_reset_tag(s->addr);
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| 290 |
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| 291 |
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| 292 | memset(stack, 0, THREAD_SIZE);
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| 293 |
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| 294 | if (memcg_charge_kernel_stack(s)) {
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| 295 | vfree(s->addr);
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| 296 | return -ENOMEM;
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| 297 | }
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| 298 |
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| 299 | tsk->stack_vm_area = s;
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| 300 | tsk->stack = stack;
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| 301 | return 0;
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| 302 | }
|
| 303 |
|
| 304 | |
| 305 | * Allocated stacks are cached and later reused by new threads,
|
| 306 | * so memcg accounting is performed manually on assigning/releasing
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| 307 | * stacks to tasks. Drop __GFP_ACCOUNT.
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| 308 |
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| 309 | stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
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| 310 | VMALLOC_START, VMALLOC_END,
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| 311 | THREADINFO_GFP & ~__GFP_ACCOUNT,
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| 312 | PAGE_KERNEL,
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| 313 | 0, node, __builtin_return_address(0));
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| 314 | if (!stack)
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| 315 | return -ENOMEM;
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| 316 |
|
| 317 | vm = find_vm_area(stack);
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| 318 | if (memcg_charge_kernel_stack(vm)) {
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| 319 | vfree(stack);
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| 320 | return -ENOMEM;
|
| 321 | }
|
| 322 | |
| 323 | * We can't call find_vm_area() in interrupt context, and
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| 324 | * free_thread_stack() can be called in interrupt context,
|
| 325 | * so cache the vm_struct.
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| 326 |
|
| 327 | tsk->stack_vm_area = vm;
|
| 328 | stack = kasan_reset_tag(stack);
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| 329 | tsk->stack = stack;
|
| 330 | return 0;
|
| 331 | }
|
| 332 |
|
| 333 | static void free_thread_stack(struct task_struct *tsk)
|
| 334 | {
|
| 335 | if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
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| 336 | thread_stack_delayed_free(tsk);
|
| 337 |
|
| 338 | tsk->stack = NULL;
|
| 339 | tsk->stack_vm_area = NULL;
|
| 340 | }
|
| 341 |
|
| 342 | # else
|
| 343 |
|
| 344 | static void thread_stack_free_rcu(struct rcu_head *rh)
|
| 345 | {
|
| 346 | __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
|
| 347 | }
|
| 348 |
|
| 349 | static void thread_stack_delayed_free(struct task_struct *tsk)
|
| 350 | {
|
| 351 | struct rcu_head *rh = tsk->stack;
|
| 352 |
|
| 353 | call_rcu(rh, thread_stack_free_rcu);
|
| 354 | }
|
| 355 |
|
| 356 | static int alloc_thread_stack_node(struct task_struct *tsk, int node)
|
| 357 | {
|
| 358 | struct page *page = alloc_pages_node(node, THREADINFO_GFP,
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| 359 | THREAD_SIZE_ORDER);
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| 360 |
|
| 361 | if (likely(page)) {
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| 362 | tsk->stack = kasan_reset_tag(page_address(page));
|
| 363 | return 0;
|
| 364 | }
|
| 365 | return -ENOMEM;
|
| 366 | }
|
| 367 |
|
| 368 | static void free_thread_stack(struct task_struct *tsk)
|
| 369 | {
|
| 370 | thread_stack_delayed_free(tsk);
|
| 371 | tsk->stack = NULL;
|
| 372 | }
|
| 373 |
|
| 374 | # endif
|
| 375 | # else
|
| 376 |
|
| 377 | static struct kmem_cache *thread_stack_cache;
|
| 378 |
|
| 379 | static void thread_stack_free_rcu(struct rcu_head *rh)
|
| 380 | {
|
| 381 | kmem_cache_free(thread_stack_cache, rh);
|
| 382 | }
|
| 383 |
|
| 384 | static void thread_stack_delayed_free(struct task_struct *tsk)
|
| 385 | {
|
| 386 | struct rcu_head *rh = tsk->stack;
|
| 387 |
|
| 388 | call_rcu(rh, thread_stack_free_rcu);
|
| 389 | }
|
| 390 |
|
| 391 | static int alloc_thread_stack_node(struct task_struct *tsk, int node)
|
| 392 | {
|
| 393 | unsigned long *stack;
|
| 394 | stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
|
| 395 | stack = kasan_reset_tag(stack);
|
| 396 | tsk->stack = stack;
|
| 397 | return stack ? 0 : -ENOMEM;
|
| 398 | }
|
| 399 |
|
| 400 | static void free_thread_stack(struct task_struct *tsk)
|
| 401 | {
|
| 402 | thread_stack_delayed_free(tsk);
|
| 403 | tsk->stack = NULL;
|
| 404 | }
|
| 405 |
|
| 406 | void thread_stack_cache_init(void)
|
| 407 | {
|
| 408 | thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
|
| 409 | THREAD_SIZE, THREAD_SIZE, 0, 0,
|
| 410 | THREAD_SIZE, NULL);
|
| 411 | BUG_ON(thread_stack_cache == NULL);
|
| 412 | }
|
| 413 |
|
| 414 | # endif
|
| 415 | #else
|
| 416 |
|
| 417 | static int alloc_thread_stack_node(struct task_struct *tsk, int node)
|
| 418 | {
|
| 419 | unsigned long *stack;
|
| 420 |
|
| 421 | stack = arch_alloc_thread_stack_node(tsk, node);
|
| 422 | tsk->stack = stack;
|
| 423 | return stack ? 0 : -ENOMEM;
|
| 424 | }
|
| 425 |
|
| 426 | static void free_thread_stack(struct task_struct *tsk)
|
| 427 | {
|
| 428 | arch_free_thread_stack(tsk);
|
| 429 | tsk->stack = NULL;
|
| 430 | }
|
| 431 |
|
| 432 | #endif
|
| 433 |
|
| 434 |
|
| 435 | static struct kmem_cache *signal_cachep;
|
| 436 |
|
| 437 |
|
| 438 | struct kmem_cache *sighand_cachep;
|
| 439 |
|
| 440 |
|
| 441 | struct kmem_cache *files_cachep;
|
| 442 |
|
| 443 |
|
| 444 | struct kmem_cache *fs_cachep;
|
| 445 |
|
| 446 |
|
| 447 | static struct kmem_cache *vm_area_cachep;
|
| 448 |
|
| 449 |
|
| 450 | static struct kmem_cache *mm_cachep;
|
| 451 |
|
| 452 | #ifdef CONFIG_PER_VMA_LOCK
|
| 453 |
|
| 454 |
|
| 455 | static struct kmem_cache *vma_lock_cachep;
|
| 456 |
|
| 457 | static bool vma_lock_alloc(struct vm_area_struct *vma)
|
| 458 | {
|
| 459 | vma->vm_lock = kmem_cache_alloc(vma_lock_cachep, GFP_KERNEL);
|
| 460 | if (!vma->vm_lock)
|
| 461 | return false;
|
| 462 |
|
| 463 | init_rwsem(&vma->vm_lock->lock);
|
| 464 | vma->vm_lock_seq = -1;
|
| 465 |
|
| 466 | return true;
|
| 467 | }
|
| 468 |
|
| 469 | static inline void vma_lock_free(struct vm_area_struct *vma)
|
| 470 | {
|
| 471 | kmem_cache_free(vma_lock_cachep, vma->vm_lock);
|
| 472 | }
|
| 473 |
|
| 474 | #else
|
| 475 |
|
| 476 | static inline bool vma_lock_alloc(struct vm_area_struct *vma) { return true; }
|
| 477 | static inline void vma_lock_free(struct vm_area_struct *vma) {}
|
| 478 |
|
| 479 | #endif
|
| 480 |
|
| 481 | struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
|
| 482 | {
|
| 483 | struct vm_area_struct *vma;
|
| 484 |
|
| 485 | vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
|
| 486 | if (!vma)
|
| 487 | return NULL;
|
| 488 |
|
| 489 | vma_init(vma, mm);
|
| 490 | if (!vma_lock_alloc(vma)) {
|
| 491 | kmem_cache_free(vm_area_cachep, vma);
|
| 492 | return NULL;
|
| 493 | }
|
| 494 |
|
| 495 | return vma;
|
| 496 | }
|
| 497 |
|
| 498 | struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
|
| 499 | {
|
| 500 | struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
|
| 501 |
|
| 502 | if (!new)
|
| 503 | return NULL;
|
| 504 |
|
| 505 | ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
|
| 506 | ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
|
| 507 | |
| 508 | * orig->shared.rb may be modified concurrently, but the clone
|
| 509 | * will be reinitialized.
|
| 510 |
|
| 511 | data_race(memcpy(new, orig, sizeof(*new)));
|
| 512 | if (!vma_lock_alloc(new)) {
|
| 513 | kmem_cache_free(vm_area_cachep, new);
|
| 514 | return NULL;
|
| 515 | }
|
| 516 | INIT_LIST_HEAD(&new->anon_vma_chain);
|
| 517 | vma_numab_state_init(new);
|
| 518 | dup_anon_vma_name(orig, new);
|
| 519 |
|
| 520 | return new;
|
| 521 | }
|
| 522 |
|
| 523 | void __vm_area_free(struct vm_area_struct *vma)
|
| 524 | {
|
| 525 | vma_numab_state_free(vma);
|
| 526 | free_anon_vma_name(vma);
|
| 527 | vma_lock_free(vma);
|
| 528 | kmem_cache_free(vm_area_cachep, vma);
|
| 529 | }
|
| 530 |
|
| 531 | #ifdef CONFIG_PER_VMA_LOCK
|
| 532 | static void vm_area_free_rcu_cb(struct rcu_head *head)
|
| 533 | {
|
| 534 | struct vm_area_struct *vma = container_of(head, struct vm_area_struct,
|
| 535 | vm_rcu);
|
| 536 |
|
| 537 |
|
| 538 | VM_BUG_ON_VMA(rwsem_is_locked(&vma->vm_lock->lock), vma);
|
| 539 | __vm_area_free(vma);
|
| 540 | }
|
| 541 | #endif
|
| 542 |
|
| 543 | void vm_area_free(struct vm_area_struct *vma)
|
| 544 | {
|
| 545 | #ifdef CONFIG_PER_VMA_LOCK
|
| 546 | call_rcu(&vma->vm_rcu, vm_area_free_rcu_cb);
|
| 547 | #else
|
| 548 | __vm_area_free(vma);
|
| 549 | #endif
|
| 550 | }
|
| 551 |
|
| 552 | static void account_kernel_stack(struct task_struct *tsk, int account)
|
| 553 | {
|
| 554 | if (IS_ENABLED(CONFIG_VMAP_STACK)) {
|
| 555 | struct vm_struct *vm = task_stack_vm_area(tsk);
|
| 556 | int i;
|
| 557 |
|
| 558 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
|
| 559 | mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
|
| 560 | account * (PAGE_SIZE / 1024));
|
| 561 | } else {
|
| 562 | void *stack = task_stack_page(tsk);
|
| 563 |
|
| 564 |
|
| 565 | mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
|
| 566 | account * (THREAD_SIZE / 1024));
|
| 567 | }
|
| 568 | }
|
| 569 |
|
| 570 | void exit_task_stack_account(struct task_struct *tsk)
|
| 571 | {
|
| 572 | account_kernel_stack(tsk, -1);
|
| 573 |
|
| 574 | if (IS_ENABLED(CONFIG_VMAP_STACK)) {
|
| 575 | struct vm_struct *vm;
|
| 576 | int i;
|
| 577 |
|
| 578 | vm = task_stack_vm_area(tsk);
|
| 579 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
|
| 580 | memcg_kmem_uncharge_page(vm->pages[i], 0);
|
| 581 | }
|
| 582 | }
|
| 583 |
|
| 584 | static void release_task_stack(struct task_struct *tsk)
|
| 585 | {
|
| 586 | if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
|
| 587 | return;
|
| 588 |
|
| 589 | free_thread_stack(tsk);
|
| 590 | }
|
| 591 |
|
| 592 | #ifdef CONFIG_THREAD_INFO_IN_TASK
|
| 593 | void put_task_stack(struct task_struct *tsk)
|
| 594 | {
|
| 595 | if (refcount_dec_and_test(&tsk->stack_refcount))
|
| 596 | release_task_stack(tsk);
|
| 597 | }
|
| 598 | #endif
|
| 599 |
|
| 600 | void free_task(struct task_struct *tsk)
|
| 601 | {
|
| 602 | #ifdef CONFIG_SECCOMP
|
| 603 | WARN_ON_ONCE(tsk->seccomp.filter);
|
| 604 | #endif
|
| 605 | release_user_cpus_ptr(tsk);
|
| 606 | scs_release(tsk);
|
| 607 |
|
| 608 | #ifndef CONFIG_THREAD_INFO_IN_TASK
|
| 609 | |
| 610 | * The task is finally done with both the stack and thread_info,
|
| 611 | * so free both.
|
| 612 |
|
| 613 | release_task_stack(tsk);
|
| 614 | #else
|
| 615 | |
| 616 | * If the task had a separate stack allocation, it should be gone
|
| 617 | * by now.
|
| 618 |
|
| 619 | WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
|
| 620 | #endif
|
| 621 | rt_mutex_debug_task_free(tsk);
|
| 622 | ftrace_graph_exit_task(tsk);
|
| 623 | arch_release_task_struct(tsk);
|
| 624 | if (tsk->flags & PF_KTHREAD)
|
| 625 | free_kthread_struct(tsk);
|
| 626 | bpf_task_storage_free(tsk);
|
| 627 | free_task_struct(tsk);
|
| 628 | }
|
| 629 | EXPORT_SYMBOL(free_task);
|
| 630 |
|
| 631 | static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
|
| 632 | {
|
| 633 | struct file *exe_file;
|
| 634 |
|
| 635 | exe_file = get_mm_exe_file(oldmm);
|
| 636 | RCU_INIT_POINTER(mm->exe_file, exe_file);
|
| 637 | |
| 638 | * We depend on the oldmm having properly denied write access to the
|
| 639 | * exe_file already.
|
| 640 |
|
| 641 | if (exe_file && deny_write_access(exe_file))
|
| 642 | pr_warn_once("deny_write_access() failed in %s\n", __func__);
|
| 643 | }
|
| 644 |
|
| 645 | #ifdef CONFIG_MMU
|
| 646 | static __latent_entropy int dup_mmap(struct mm_struct *mm,
|
| 647 | struct mm_struct *oldmm)
|
| 648 | {
|
| 649 | struct vm_area_struct *mpnt, *tmp;
|
| 650 | int retval;
|
| 651 | unsigned long charge = 0;
|
| 652 | LIST_HEAD(uf);
|
| 653 | VMA_ITERATOR(old_vmi, oldmm, 0);
|
| 654 | VMA_ITERATOR(vmi, mm, 0);
|
| 655 |
|
| 656 | uprobe_start_dup_mmap();
|
| 657 | if (mmap_write_lock_killable(oldmm)) {
|
| 658 | retval = -EINTR;
|
| 659 | goto fail_uprobe_end;
|
| 660 | }
|
| 661 | flush_cache_dup_mm(oldmm);
|
| 662 | uprobe_dup_mmap(oldmm, mm);
|
| 663 | |
| 664 | * Not linked in yet - no deadlock potential:
|
| 665 |
|
| 666 | mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
|
| 667 |
|
| 668 |
|
| 669 | dup_mm_exe_file(mm, oldmm);
|
| 670 |
|
| 671 | mm->total_vm = oldmm->total_vm;
|
| 672 | mm->data_vm = oldmm->data_vm;
|
| 673 | mm->exec_vm = oldmm->exec_vm;
|
| 674 | mm->stack_vm = oldmm->stack_vm;
|
| 675 |
|
| 676 | retval = ksm_fork(mm, oldmm);
|
| 677 | if (retval)
|
| 678 | goto out;
|
| 679 | khugepaged_fork(mm, oldmm);
|
| 680 |
|
| 681 | retval = vma_iter_bulk_alloc(&vmi, oldmm->map_count);
|
| 682 | if (retval)
|
| 683 | goto out;
|
| 684 |
|
| 685 | mt_clear_in_rcu(vmi.mas.tree);
|
| 686 | for_each_vma(old_vmi, mpnt) {
|
| 687 | struct file *file;
|
| 688 |
|
| 689 | vma_start_write(mpnt);
|
| 690 | if (mpnt->vm_flags & VM_DONTCOPY) {
|
| 691 | vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
|
| 692 | continue;
|
| 693 | }
|
| 694 | charge = 0;
|
| 695 | |
| 696 | * Don't duplicate many vmas if we've been oom-killed (for
|
| 697 | * example)
|
| 698 |
|
| 699 | if (fatal_signal_pending(current)) {
|
| 700 | retval = -EINTR;
|
| 701 | goto loop_out;
|
| 702 | }
|
| 703 | if (mpnt->vm_flags & VM_ACCOUNT) {
|
| 704 | unsigned long len = vma_pages(mpnt);
|
| 705 |
|
| 706 | if (security_vm_enough_memory_mm(oldmm, len))
|
| 707 | goto fail_nomem;
|
| 708 | charge = len;
|
| 709 | }
|
| 710 | tmp = vm_area_dup(mpnt);
|
| 711 | if (!tmp)
|
| 712 | goto fail_nomem;
|
| 713 | retval = vma_dup_policy(mpnt, tmp);
|
| 714 | if (retval)
|
| 715 | goto fail_nomem_policy;
|
| 716 | tmp->vm_mm = mm;
|
| 717 | retval = dup_userfaultfd(tmp, &uf);
|
| 718 | if (retval)
|
| 719 | goto fail_nomem_anon_vma_fork;
|
| 720 | if (tmp->vm_flags & VM_WIPEONFORK) {
|
| 721 | |
| 722 | * VM_WIPEONFORK gets a clean slate in the child.
|
| 723 | * Don't prepare anon_vma until fault since we don't
|
| 724 | * copy page for current vma.
|
| 725 |
|
| 726 | tmp->anon_vma = NULL;
|
| 727 | } else if (anon_vma_fork(tmp, mpnt))
|
| 728 | goto fail_nomem_anon_vma_fork;
|
| 729 | vm_flags_clear(tmp, VM_LOCKED_MASK);
|
| 730 | file = tmp->vm_file;
|
| 731 | if (file) {
|
| 732 | struct address_space *mapping = file->f_mapping;
|
| 733 |
|
| 734 | get_file(file);
|
| 735 | i_mmap_lock_write(mapping);
|
| 736 | if (vma_is_shared_maywrite(tmp))
|
| 737 | mapping_allow_writable(mapping);
|
| 738 | flush_dcache_mmap_lock(mapping);
|
| 739 |
|
| 740 | vma_interval_tree_insert_after(tmp, mpnt,
|
| 741 | &mapping->i_mmap);
|
| 742 | flush_dcache_mmap_unlock(mapping);
|
| 743 | i_mmap_unlock_write(mapping);
|
| 744 | }
|
| 745 |
|
| 746 | |
| 747 | * Copy/update hugetlb private vma information.
|
| 748 |
|
| 749 | if (is_vm_hugetlb_page(tmp))
|
| 750 | hugetlb_dup_vma_private(tmp);
|
| 751 |
|
| 752 |
|
| 753 | if (vma_iter_bulk_store(&vmi, tmp))
|
| 754 | goto fail_nomem_vmi_store;
|
| 755 |
|
| 756 | mm->map_count++;
|
| 757 | if (!(tmp->vm_flags & VM_WIPEONFORK))
|
| 758 | retval = copy_page_range(tmp, mpnt);
|
| 759 |
|
| 760 | if (tmp->vm_ops && tmp->vm_ops->open)
|
| 761 | tmp->vm_ops->open(tmp);
|
| 762 |
|
| 763 | if (retval)
|
| 764 | goto loop_out;
|
| 765 | }
|
| 766 |
|
| 767 | retval = arch_dup_mmap(oldmm, mm);
|
| 768 | loop_out:
|
| 769 | vma_iter_free(&vmi);
|
| 770 | if (!retval)
|
| 771 | mt_set_in_rcu(vmi.mas.tree);
|
| 772 | out:
|
| 773 | mmap_write_unlock(mm);
|
| 774 | flush_tlb_mm(oldmm);
|
| 775 | mmap_write_unlock(oldmm);
|
| 776 | dup_userfaultfd_complete(&uf);
|
| 777 | fail_uprobe_end:
|
| 778 | uprobe_end_dup_mmap();
|
| 779 | return retval;
|
| 780 |
|
| 781 | fail_nomem_vmi_store:
|
| 782 | unlink_anon_vmas(tmp);
|
| 783 | fail_nomem_anon_vma_fork:
|
| 784 | mpol_put(vma_policy(tmp));
|
| 785 | fail_nomem_policy:
|
| 786 | vm_area_free(tmp);
|
| 787 | fail_nomem:
|
| 788 | retval = -ENOMEM;
|
| 789 | vm_unacct_memory(charge);
|
| 790 | goto loop_out;
|
| 791 | }
|
| 792 |
|
| 793 | static inline int mm_alloc_pgd(struct mm_struct *mm)
|
| 794 | {
|
| 795 | mm->pgd = pgd_alloc(mm);
|
| 796 | if (unlikely(!mm->pgd))
|
| 797 | return -ENOMEM;
|
| 798 | return 0;
|
| 799 | }
|
| 800 |
|
| 801 | static inline void mm_free_pgd(struct mm_struct *mm)
|
| 802 | {
|
| 803 | pgd_free(mm, mm->pgd);
|
| 804 | }
|
| 805 | #else
|
| 806 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
|
| 807 | {
|
| 808 | mmap_write_lock(oldmm);
|
| 809 | dup_mm_exe_file(mm, oldmm);
|
| 810 | mmap_write_unlock(oldmm);
|
| 811 | return 0;
|
| 812 | }
|
| 813 | #define mm_alloc_pgd(mm) (0)
|
| 814 | #define mm_free_pgd(mm)
|
| 815 | #endif
|
| 816 |
|
| 817 | static void check_mm(struct mm_struct *mm)
|
| 818 | {
|
| 819 | int i;
|
| 820 |
|
| 821 | BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
|
| 822 | "Please make sure 'struct resident_page_types[]' is updated as well");
|
| 823 |
|
| 824 | for (i = 0; i < NR_MM_COUNTERS; i++) {
|
| 825 | long x = percpu_counter_sum(&mm->rss_stat[i]);
|
| 826 |
|
| 827 | if (unlikely(x))
|
| 828 | pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
|
| 829 | mm, resident_page_types[i], x);
|
| 830 | }
|
| 831 |
|
| 832 | if (mm_pgtables_bytes(mm))
|
| 833 | pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
|
| 834 | mm_pgtables_bytes(mm));
|
| 835 |
|
| 836 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
|
| 837 | VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
|
| 838 | #endif
|
| 839 | }
|
| 840 |
|
| 841 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
|
| 842 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
|
| 843 |
|
| 844 | static void do_check_lazy_tlb(void *arg)
|
| 845 | {
|
| 846 | struct mm_struct *mm = arg;
|
| 847 |
|
| 848 | WARN_ON_ONCE(current->active_mm == mm);
|
| 849 | }
|
| 850 |
|
| 851 | static void do_shoot_lazy_tlb(void *arg)
|
| 852 | {
|
| 853 | struct mm_struct *mm = arg;
|
| 854 |
|
| 855 | if (current->active_mm == mm) {
|
| 856 | WARN_ON_ONCE(current->mm);
|
| 857 | current->active_mm = &init_mm;
|
| 858 | switch_mm(mm, &init_mm, current);
|
| 859 | }
|
| 860 | }
|
| 861 |
|
| 862 | static void cleanup_lazy_tlbs(struct mm_struct *mm)
|
| 863 | {
|
| 864 | if (!IS_ENABLED(CONFIG_MMU_LAZY_TLB_SHOOTDOWN)) {
|
| 865 | |
| 866 | * In this case, lazy tlb mms are refounted and would not reach
|
| 867 | * __mmdrop until all CPUs have switched away and mmdrop()ed.
|
| 868 |
|
| 869 | return;
|
| 870 | }
|
| 871 |
|
| 872 | |
| 873 | * Lazy mm shootdown does not refcount "lazy tlb mm" usage, rather it
|
| 874 | * requires lazy mm users to switch to another mm when the refcount
|
| 875 | * drops to zero, before the mm is freed. This requires IPIs here to
|
| 876 | * switch kernel threads to init_mm.
|
| 877 | *
|
| 878 | * archs that use IPIs to flush TLBs can piggy-back that lazy tlb mm
|
| 879 | * switch with the final userspace teardown TLB flush which leaves the
|
| 880 | * mm lazy on this CPU but no others, reducing the need for additional
|
| 881 | * IPIs here. There are cases where a final IPI is still required here,
|
| 882 | * such as the final mmdrop being performed on a different CPU than the
|
| 883 | * one exiting, or kernel threads using the mm when userspace exits.
|
| 884 | *
|
| 885 | * IPI overheads have not found to be expensive, but they could be
|
| 886 | * reduced in a number of possible ways, for example (roughly
|
| 887 | * increasing order of complexity):
|
| 888 | * - The last lazy reference created by exit_mm() could instead switch
|
| 889 | * to init_mm, however it's probable this will run on the same CPU
|
| 890 | * immediately afterwards, so this may not reduce IPIs much.
|
| 891 | * - A batch of mms requiring IPIs could be gathered and freed at once.
|
| 892 | * - CPUs store active_mm where it can be remotely checked without a
|
| 893 | * lock, to filter out false-positives in the cpumask.
|
| 894 | * - After mm_users or mm_count reaches zero, switching away from the
|
| 895 | * mm could clear mm_cpumask to reduce some IPIs, perhaps together
|
| 896 | * with some batching or delaying of the final IPIs.
|
| 897 | * - A delayed freeing and RCU-like quiescing sequence based on mm
|
| 898 | * switching to avoid IPIs completely.
|
| 899 |
|
| 900 | on_each_cpu_mask(mm_cpumask(mm), do_shoot_lazy_tlb, (void *)mm, 1);
|
| 901 | if (IS_ENABLED(CONFIG_DEBUG_VM_SHOOT_LAZIES))
|
| 902 | on_each_cpu(do_check_lazy_tlb, (void *)mm, 1);
|
| 903 | }
|
| 904 |
|
| 905 | |
| 906 | * Called when the last reference to the mm
|
| 907 | * is dropped: either by a lazy thread or by
|
| 908 | * mmput. Free the page directory and the mm.
|
| 909 |
|
| 910 | void __mmdrop(struct mm_struct *mm)
|
| 911 | {
|
| 912 | BUG_ON(mm == &init_mm);
|
| 913 | WARN_ON_ONCE(mm == current->mm);
|
| 914 |
|
| 915 |
|
| 916 | cleanup_lazy_tlbs(mm);
|
| 917 |
|
| 918 | WARN_ON_ONCE(mm == current->active_mm);
|
| 919 | mm_free_pgd(mm);
|
| 920 | destroy_context(mm);
|
| 921 | mmu_notifier_subscriptions_destroy(mm);
|
| 922 | check_mm(mm);
|
| 923 | put_user_ns(mm->user_ns);
|
| 924 | mm_pasid_drop(mm);
|
| 925 | mm_destroy_cid(mm);
|
| 926 | percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS);
|
| 927 |
|
| 928 | free_mm(mm);
|
| 929 | }
|
| 930 | EXPORT_SYMBOL_GPL(__mmdrop);
|
| 931 |
|
| 932 | static void mmdrop_async_fn(struct work_struct *work)
|
| 933 | {
|
| 934 | struct mm_struct *mm;
|
| 935 |
|
| 936 | mm = container_of(work, struct mm_struct, async_put_work);
|
| 937 | __mmdrop(mm);
|
| 938 | }
|
| 939 |
|
| 940 | static void mmdrop_async(struct mm_struct *mm)
|
| 941 | {
|
| 942 | if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
|
| 943 | INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
|
| 944 | schedule_work(&mm->async_put_work);
|
| 945 | }
|
| 946 | }
|
| 947 |
|
| 948 | static inline void free_signal_struct(struct signal_struct *sig)
|
| 949 | {
|
| 950 | taskstats_tgid_free(sig);
|
| 951 | sched_autogroup_exit(sig);
|
| 952 | |
| 953 | * __mmdrop is not safe to call from softirq context on x86 due to
|
| 954 | * pgd_dtor so postpone it to the async context
|
| 955 |
|
| 956 | if (sig->oom_mm)
|
| 957 | mmdrop_async(sig->oom_mm);
|
| 958 | kmem_cache_free(signal_cachep, sig);
|
| 959 | }
|
| 960 |
|
| 961 | static inline void put_signal_struct(struct signal_struct *sig)
|
| 962 | {
|
| 963 | if (refcount_dec_and_test(&sig->sigcnt))
|
| 964 | free_signal_struct(sig);
|
| 965 | }
|
| 966 |
|
| 967 | void __put_task_struct(struct task_struct *tsk)
|
| 968 | {
|
| 969 | WARN_ON(!tsk->exit_state);
|
| 970 | WARN_ON(refcount_read(&tsk->usage));
|
| 971 | WARN_ON(tsk == current);
|
| 972 |
|
| 973 | io_uring_free(tsk);
|
| 974 | cgroup_free(tsk);
|
| 975 | task_numa_free(tsk, true);
|
| 976 | security_task_free(tsk);
|
| 977 | exit_creds(tsk);
|
| 978 | delayacct_tsk_free(tsk);
|
| 979 | put_signal_struct(tsk->signal);
|
| 980 | sched_core_free(tsk);
|
| 981 | free_task(tsk);
|
| 982 | }
|
| 983 | EXPORT_SYMBOL_GPL(__put_task_struct);
|
| 984 |
|
| 985 | void __put_task_struct_rcu_cb(struct rcu_head *rhp)
|
| 986 | {
|
| 987 | struct task_struct *task = container_of(rhp, struct task_struct, rcu);
|
| 988 |
|
| 989 | __put_task_struct(task);
|
| 990 | }
|
| 991 | EXPORT_SYMBOL_GPL(__put_task_struct_rcu_cb);
|
| 992 |
|
| 993 | void __init __weak arch_task_cache_init(void) { }
|
| 994 |
|
| 995 | |
| 996 | * set_max_threads
|
| 997 |
|
| 998 | static void set_max_threads(unsigned int max_threads_suggested)
|
| 999 | {
|
| 1000 | u64 threads;
|
| 1001 | unsigned long nr_pages = totalram_pages();
|
| 1002 |
|
| 1003 | |
| 1004 | * The number of threads shall be limited such that the thread
|
| 1005 | * structures may only consume a small part of the available memory.
|
| 1006 |
|
| 1007 | if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
|
| 1008 | threads = MAX_THREADS;
|
| 1009 | else
|
| 1010 | threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
|
| 1011 | (u64) THREAD_SIZE * 8UL);
|
| 1012 |
|
| 1013 | if (threads > max_threads_suggested)
|
| 1014 | threads = max_threads_suggested;
|
| 1015 |
|
| 1016 | max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
|
| 1017 | }
|
| 1018 |
|
| 1019 | #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
|
| 1020 |
|
| 1021 | int arch_task_struct_size __read_mostly;
|
| 1022 | #endif
|
| 1023 |
|
| 1024 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
|
| 1025 | static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
|
| 1026 | {
|
| 1027 |
|
| 1028 | arch_thread_struct_whitelist(offset, size);
|
| 1029 |
|
| 1030 | |
| 1031 | * Handle zero-sized whitelist or empty thread_struct, otherwise
|
| 1032 | * adjust offset to position of thread_struct in task_struct.
|
| 1033 |
|
| 1034 | if (unlikely(*size == 0))
|
| 1035 | *offset = 0;
|
| 1036 | else
|
| 1037 | *offset += offsetof(struct task_struct, thread);
|
| 1038 | }
|
| 1039 | #endif
|
| 1040 |
|
| 1041 | void __init fork_init(void)
|
| 1042 | {
|
| 1043 | int i;
|
| 1044 | #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
|
| 1045 | #ifndef ARCH_MIN_TASKALIGN
|
| 1046 | #define ARCH_MIN_TASKALIGN 0
|
| 1047 | #endif
|
| 1048 | int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
|
| 1049 | unsigned long useroffset, usersize;
|
| 1050 |
|
| 1051 |
|
| 1052 | task_struct_whitelist(&useroffset, &usersize);
|
| 1053 | task_struct_cachep = kmem_cache_create_usercopy("task_struct",
|
| 1054 | arch_task_struct_size, align,
|
| 1055 | SLAB_PANIC|SLAB_ACCOUNT,
|
| 1056 | useroffset, usersize, NULL);
|
| 1057 | #endif
|
| 1058 |
|
| 1059 |
|
| 1060 | arch_task_cache_init();
|
| 1061 |
|
| 1062 | set_max_threads(MAX_THREADS);
|
| 1063 |
|
| 1064 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
|
| 1065 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
|
| 1066 | init_task.signal->rlim[RLIMIT_SIGPENDING] =
|
| 1067 | init_task.signal->rlim[RLIMIT_NPROC];
|
| 1068 |
|
| 1069 | for (i = 0; i < UCOUNT_COUNTS; i++)
|
| 1070 | init_user_ns.ucount_max[i] = max_threads/2;
|
| 1071 |
|
| 1072 | set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
|
| 1073 | set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
|
| 1074 | set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
|
| 1075 | set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
|
| 1076 |
|
| 1077 | #ifdef CONFIG_VMAP_STACK
|
| 1078 | cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
|
| 1079 | NULL, free_vm_stack_cache);
|
| 1080 | #endif
|
| 1081 |
|
| 1082 | scs_init();
|
| 1083 |
|
| 1084 | lockdep_init_task(&init_task);
|
| 1085 | uprobes_init();
|
| 1086 | }
|
| 1087 |
|
| 1088 | int __weak arch_dup_task_struct(struct task_struct *dst,
|
| 1089 | struct task_struct *src)
|
| 1090 | {
|
| 1091 | *dst = *src;
|
| 1092 | return 0;
|
| 1093 | }
|
| 1094 |
|
| 1095 | void set_task_stack_end_magic(struct task_struct *tsk)
|
| 1096 | {
|
| 1097 | unsigned long *stackend;
|
| 1098 |
|
| 1099 | stackend = end_of_stack(tsk);
|
| 1100 | *stackend = STACK_END_MAGIC;
|
| 1101 | }
|
| 1102 |
|
| 1103 | static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
|
| 1104 | {
|
| 1105 | struct task_struct *tsk;
|
| 1106 | int err;
|
| 1107 |
|
| 1108 | if (node == NUMA_NO_NODE)
|
| 1109 | node = tsk_fork_get_node(orig);
|
| 1110 | tsk = alloc_task_struct_node(node);
|
| 1111 | if (!tsk)
|
| 1112 | return NULL;
|
| 1113 |
|
| 1114 | err = arch_dup_task_struct(tsk, orig);
|
| 1115 | if (err)
|
| 1116 | goto free_tsk;
|
| 1117 |
|
| 1118 | err = alloc_thread_stack_node(tsk, node);
|
| 1119 | if (err)
|
| 1120 | goto free_tsk;
|
| 1121 |
|
| 1122 | #ifdef CONFIG_THREAD_INFO_IN_TASK
|
| 1123 | refcount_set(&tsk->stack_refcount, 1);
|
| 1124 | #endif
|
| 1125 | account_kernel_stack(tsk, 1);
|
| 1126 |
|
| 1127 | err = scs_prepare(tsk, node);
|
| 1128 | if (err)
|
| 1129 | goto free_stack;
|
| 1130 |
|
| 1131 | #ifdef CONFIG_SECCOMP
|
| 1132 | |
| 1133 | * We must handle setting up seccomp filters once we're under
|
| 1134 | * the sighand lock in case orig has changed between now and
|
| 1135 | * then. Until then, filter must be NULL to avoid messing up
|
| 1136 | * the usage counts on the error path calling free_task.
|
| 1137 |
|
| 1138 | tsk->seccomp.filter = NULL;
|
| 1139 | #endif
|
| 1140 |
|
| 1141 | setup_thread_stack(tsk, orig);
|
| 1142 | clear_user_return_notifier(tsk);
|
| 1143 | clear_tsk_need_resched(tsk);
|
| 1144 | set_task_stack_end_magic(tsk);
|
| 1145 | clear_syscall_work_syscall_user_dispatch(tsk);
|
| 1146 |
|
| 1147 | #ifdef CONFIG_STACKPROTECTOR
|
| 1148 | tsk->stack_canary = get_random_canary();
|
| 1149 | #endif
|
| 1150 | if (orig->cpus_ptr == &orig->cpus_mask)
|
| 1151 | tsk->cpus_ptr = &tsk->cpus_mask;
|
| 1152 | dup_user_cpus_ptr(tsk, orig, node);
|
| 1153 |
|
| 1154 | |
| 1155 | * One for the user space visible state that goes away when reaped.
|
| 1156 | * One for the scheduler.
|
| 1157 |
|
| 1158 | refcount_set(&tsk->rcu_users, 2);
|
| 1159 |
|
| 1160 | refcount_set(&tsk->usage, 1);
|
| 1161 | #ifdef CONFIG_BLK_DEV_IO_TRACE
|
| 1162 | tsk->btrace_seq = 0;
|
| 1163 | #endif
|
| 1164 | tsk->splice_pipe = NULL;
|
| 1165 | tsk->task_frag.page = NULL;
|
| 1166 | tsk->wake_q.next = NULL;
|
| 1167 | tsk->worker_private = NULL;
|
| 1168 |
|
| 1169 | kcov_task_init(tsk);
|
| 1170 | kmsan_task_create(tsk);
|
| 1171 | kmap_local_fork(tsk);
|
| 1172 |
|
| 1173 | #ifdef CONFIG_FAULT_INJECTION
|
| 1174 | tsk->fail_nth = 0;
|
| 1175 | #endif
|
| 1176 |
|
| 1177 | #ifdef CONFIG_BLK_CGROUP
|
| 1178 | tsk->throttle_disk = NULL;
|
| 1179 | tsk->use_memdelay = 0;
|
| 1180 | #endif
|
| 1181 |
|
| 1182 | #ifdef CONFIG_IOMMU_SVA
|
| 1183 | tsk->pasid_activated = 0;
|
| 1184 | #endif
|
| 1185 |
|
| 1186 | #ifdef CONFIG_MEMCG
|
| 1187 | tsk->active_memcg = NULL;
|
| 1188 | #endif
|
| 1189 |
|
| 1190 | #ifdef CONFIG_CPU_SUP_INTEL
|
| 1191 | tsk->reported_split_lock = 0;
|
| 1192 | #endif
|
| 1193 |
|
| 1194 | #ifdef CONFIG_SCHED_MM_CID
|
| 1195 | tsk->mm_cid = -1;
|
| 1196 | tsk->last_mm_cid = -1;
|
| 1197 | tsk->mm_cid_active = 0;
|
| 1198 | tsk->migrate_from_cpu = -1;
|
| 1199 | #endif
|
| 1200 | return tsk;
|
| 1201 |
|
| 1202 | free_stack:
|
| 1203 | exit_task_stack_account(tsk);
|
| 1204 | free_thread_stack(tsk);
|
| 1205 | free_tsk:
|
| 1206 | free_task_struct(tsk);
|
| 1207 | return NULL;
|
| 1208 | }
|
| 1209 |
|
| 1210 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
|
| 1211 |
|
| 1212 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
|
| 1213 |
|
| 1214 | static int __init coredump_filter_setup(char *s)
|
| 1215 | {
|
| 1216 | default_dump_filter =
|
| 1217 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
|
| 1218 | MMF_DUMP_FILTER_MASK;
|
| 1219 | return 1;
|
| 1220 | }
|
| 1221 |
|
| 1222 | __setup("coredump_filter=", coredump_filter_setup);
|
| 1223 |
|
| 1224 | #include <linux/init_task.h>
|
| 1225 |
|
| 1226 | static void mm_init_aio(struct mm_struct *mm)
|
| 1227 | {
|
| 1228 | #ifdef CONFIG_AIO
|
| 1229 | spin_lock_init(&mm->ioctx_lock);
|
| 1230 | mm->ioctx_table = NULL;
|
| 1231 | #endif
|
| 1232 | }
|
| 1233 |
|
| 1234 | static __always_inline void mm_clear_owner(struct mm_struct *mm,
|
| 1235 | struct task_struct *p)
|
| 1236 | {
|
| 1237 | #ifdef CONFIG_MEMCG
|
| 1238 | if (mm->owner == p)
|
| 1239 | WRITE_ONCE(mm->owner, NULL);
|
| 1240 | #endif
|
| 1241 | }
|
| 1242 |
|
| 1243 | static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
|
| 1244 | {
|
| 1245 | #ifdef CONFIG_MEMCG
|
| 1246 | mm->owner = p;
|
| 1247 | #endif
|
| 1248 | }
|
| 1249 |
|
| 1250 | static void mm_init_uprobes_state(struct mm_struct *mm)
|
| 1251 | {
|
| 1252 | #ifdef CONFIG_UPROBES
|
| 1253 | mm->uprobes_state.xol_area = NULL;
|
| 1254 | #endif
|
| 1255 | }
|
| 1256 |
|
| 1257 | static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
|
| 1258 | struct user_namespace *user_ns)
|
| 1259 | {
|
| 1260 | mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
|
| 1261 | mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
|
| 1262 | atomic_set(&mm->mm_users, 1);
|
| 1263 | atomic_set(&mm->mm_count, 1);
|
| 1264 | seqcount_init(&mm->write_protect_seq);
|
| 1265 | mmap_init_lock(mm);
|
| 1266 | INIT_LIST_HEAD(&mm->mmlist);
|
| 1267 | #ifdef CONFIG_PER_VMA_LOCK
|
| 1268 | mm->mm_lock_seq = 0;
|
| 1269 | #endif
|
| 1270 | mm_pgtables_bytes_init(mm);
|
| 1271 | mm->map_count = 0;
|
| 1272 | mm->locked_vm = 0;
|
| 1273 | atomic64_set(&mm->pinned_vm, 0);
|
| 1274 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
|
| 1275 | spin_lock_init(&mm->page_table_lock);
|
| 1276 | spin_lock_init(&mm->arg_lock);
|
| 1277 | mm_init_cpumask(mm);
|
| 1278 | mm_init_aio(mm);
|
| 1279 | mm_init_owner(mm, p);
|
| 1280 | mm_pasid_init(mm);
|
| 1281 | RCU_INIT_POINTER(mm->exe_file, NULL);
|
| 1282 | mmu_notifier_subscriptions_init(mm);
|
| 1283 | init_tlb_flush_pending(mm);
|
| 1284 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
|
| 1285 | mm->pmd_huge_pte = NULL;
|
| 1286 | #endif
|
| 1287 | mm_init_uprobes_state(mm);
|
| 1288 | hugetlb_count_init(mm);
|
| 1289 |
|
| 1290 | if (current->mm) {
|
| 1291 | mm->flags = mmf_init_flags(current->mm->flags);
|
| 1292 | mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
|
| 1293 | } else {
|
| 1294 | mm->flags = default_dump_filter;
|
| 1295 | mm->def_flags = 0;
|
| 1296 | }
|
| 1297 |
|
| 1298 | if (mm_alloc_pgd(mm))
|
| 1299 | goto fail_nopgd;
|
| 1300 |
|
| 1301 | if (init_new_context(p, mm))
|
| 1302 | goto fail_nocontext;
|
| 1303 |
|
| 1304 | if (mm_alloc_cid(mm))
|
| 1305 | goto fail_cid;
|
| 1306 |
|
| 1307 | if (percpu_counter_init_many(mm->rss_stat, 0, GFP_KERNEL_ACCOUNT,
|
| 1308 | NR_MM_COUNTERS))
|
| 1309 | goto fail_pcpu;
|
| 1310 |
|
| 1311 | mm->user_ns = get_user_ns(user_ns);
|
| 1312 | lru_gen_init_mm(mm);
|
| 1313 | return mm;
|
| 1314 |
|
| 1315 | fail_pcpu:
|
| 1316 | mm_destroy_cid(mm);
|
| 1317 | fail_cid:
|
| 1318 | destroy_context(mm);
|
| 1319 | fail_nocontext:
|
| 1320 | mm_free_pgd(mm);
|
| 1321 | fail_nopgd:
|
| 1322 | free_mm(mm);
|
| 1323 | return NULL;
|
| 1324 | }
|
| 1325 |
|
| 1326 | |
| 1327 | * Allocate and initialize an mm_struct.
|
| 1328 |
|
| 1329 | struct mm_struct *mm_alloc(void)
|
| 1330 | {
|
| 1331 | struct mm_struct *mm;
|
| 1332 |
|
| 1333 | mm = allocate_mm();
|
| 1334 | if (!mm)
|
| 1335 | return NULL;
|
| 1336 |
|
| 1337 | memset(mm, 0, sizeof(*mm));
|
| 1338 | return mm_init(mm, current, current_user_ns());
|
| 1339 | }
|
| 1340 |
|
| 1341 | static inline void __mmput(struct mm_struct *mm)
|
| 1342 | {
|
| 1343 | VM_BUG_ON(atomic_read(&mm->mm_users));
|
| 1344 |
|
| 1345 | uprobe_clear_state(mm);
|
| 1346 | exit_aio(mm);
|
| 1347 | ksm_exit(mm);
|
| 1348 | khugepaged_exit(mm);
|
| 1349 | exit_mmap(mm);
|
| 1350 | mm_put_huge_zero_page(mm);
|
| 1351 | set_mm_exe_file(mm, NULL);
|
| 1352 | if (!list_empty(&mm->mmlist)) {
|
| 1353 | spin_lock(&mmlist_lock);
|
| 1354 | list_del(&mm->mmlist);
|
| 1355 | spin_unlock(&mmlist_lock);
|
| 1356 | }
|
| 1357 | if (mm->binfmt)
|
| 1358 | module_put(mm->binfmt->module);
|
| 1359 | lru_gen_del_mm(mm);
|
| 1360 | mmdrop(mm);
|
| 1361 | }
|
| 1362 |
|
| 1363 | |
| 1364 | * Decrement the use count and release all resources for an mm.
|
| 1365 |
|
| 1366 | void mmput(struct mm_struct *mm)
|
| 1367 | {
|
| 1368 | might_sleep();
|
| 1369 |
|
| 1370 | if (atomic_dec_and_test(&mm->mm_users))
|
| 1371 | __mmput(mm);
|
| 1372 | }
|
| 1373 | EXPORT_SYMBOL_GPL(mmput);
|
| 1374 |
|
| 1375 | #ifdef CONFIG_MMU
|
| 1376 | static void mmput_async_fn(struct work_struct *work)
|
| 1377 | {
|
| 1378 | struct mm_struct *mm = container_of(work, struct mm_struct,
|
| 1379 | async_put_work);
|
| 1380 |
|
| 1381 | __mmput(mm);
|
| 1382 | }
|
| 1383 |
|
| 1384 | void mmput_async(struct mm_struct *mm)
|
| 1385 | {
|
| 1386 | if (atomic_dec_and_test(&mm->mm_users)) {
|
| 1387 | INIT_WORK(&mm->async_put_work, mmput_async_fn);
|
| 1388 | schedule_work(&mm->async_put_work);
|
| 1389 | }
|
| 1390 | }
|
| 1391 | EXPORT_SYMBOL_GPL(mmput_async);
|
| 1392 | #endif
|
| 1393 |
|
| 1394 | |
| 1395 | * set_mm_exe_file - change a reference to the mm's executable file
|
| 1396 | * @mm: The mm to change.
|
| 1397 | * @new_exe_file: The new file to use.
|
| 1398 | *
|
| 1399 | * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
|
| 1400 | *
|
| 1401 | * Main users are mmput() and sys_execve(). Callers prevent concurrent
|
| 1402 | * invocations: in mmput() nobody alive left, in execve it happens before
|
| 1403 | * the new mm is made visible to anyone.
|
| 1404 | *
|
| 1405 | * Can only fail if new_exe_file != NULL.
|
| 1406 |
|
| 1407 | int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
|
| 1408 | {
|
| 1409 | struct file *old_exe_file;
|
| 1410 |
|
| 1411 | |
| 1412 | * It is safe to dereference the exe_file without RCU as
|
| 1413 | * this function is only called if nobody else can access
|
| 1414 | * this mm -- see comment above for justification.
|
| 1415 |
|
| 1416 | old_exe_file = rcu_dereference_raw(mm->exe_file);
|
| 1417 |
|
| 1418 | if (new_exe_file) {
|
| 1419 | |
| 1420 | * We expect the caller (i.e., sys_execve) to already denied
|
| 1421 | * write access, so this is unlikely to fail.
|
| 1422 |
|
| 1423 | if (unlikely(deny_write_access(new_exe_file)))
|
| 1424 | return -EACCES;
|
| 1425 | get_file(new_exe_file);
|
| 1426 | }
|
| 1427 | rcu_assign_pointer(mm->exe_file, new_exe_file);
|
| 1428 | if (old_exe_file) {
|
| 1429 | allow_write_access(old_exe_file);
|
| 1430 | fput(old_exe_file);
|
| 1431 | }
|
| 1432 | return 0;
|
| 1433 | }
|
| 1434 |
|
| 1435 | |
| 1436 | * replace_mm_exe_file - replace a reference to the mm's executable file
|
| 1437 | * @mm: The mm to change.
|
| 1438 | * @new_exe_file: The new file to use.
|
| 1439 | *
|
| 1440 | * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
|
| 1441 | *
|
| 1442 | * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
|
| 1443 |
|
| 1444 | int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
|
| 1445 | {
|
| 1446 | struct vm_area_struct *vma;
|
| 1447 | struct file *old_exe_file;
|
| 1448 | int ret = 0;
|
| 1449 |
|
| 1450 |
|
| 1451 | old_exe_file = get_mm_exe_file(mm);
|
| 1452 | if (old_exe_file) {
|
| 1453 | VMA_ITERATOR(vmi, mm, 0);
|
| 1454 | mmap_read_lock(mm);
|
| 1455 | for_each_vma(vmi, vma) {
|
| 1456 | if (!vma->vm_file)
|
| 1457 | continue;
|
| 1458 | if (path_equal(&vma->vm_file->f_path,
|
| 1459 | &old_exe_file->f_path)) {
|
| 1460 | ret = -EBUSY;
|
| 1461 | break;
|
| 1462 | }
|
| 1463 | }
|
| 1464 | mmap_read_unlock(mm);
|
| 1465 | fput(old_exe_file);
|
| 1466 | if (ret)
|
| 1467 | return ret;
|
| 1468 | }
|
| 1469 |
|
| 1470 | ret = deny_write_access(new_exe_file);
|
| 1471 | if (ret)
|
| 1472 | return -EACCES;
|
| 1473 | get_file(new_exe_file);
|
| 1474 |
|
| 1475 |
|
| 1476 | mmap_write_lock(mm);
|
| 1477 | old_exe_file = rcu_dereference_raw(mm->exe_file);
|
| 1478 | rcu_assign_pointer(mm->exe_file, new_exe_file);
|
| 1479 | mmap_write_unlock(mm);
|
| 1480 |
|
| 1481 | if (old_exe_file) {
|
| 1482 | allow_write_access(old_exe_file);
|
| 1483 | fput(old_exe_file);
|
| 1484 | }
|
| 1485 | return 0;
|
| 1486 | }
|
| 1487 |
|
| 1488 | |
| 1489 | * get_mm_exe_file - acquire a reference to the mm's executable file
|
| 1490 | * @mm: The mm of interest.
|
| 1491 | *
|
| 1492 | * Returns %NULL if mm has no associated executable file.
|
| 1493 | * User must release file via fput().
|
| 1494 |
|
| 1495 | struct file *get_mm_exe_file(struct mm_struct *mm)
|
| 1496 | {
|
| 1497 | struct file *exe_file;
|
| 1498 |
|
| 1499 | rcu_read_lock();
|
| 1500 | exe_file = get_file_rcu(&mm->exe_file);
|
| 1501 | rcu_read_unlock();
|
| 1502 | return exe_file;
|
| 1503 | }
|
| 1504 |
|
| 1505 | |
| 1506 | * get_task_exe_file - acquire a reference to the task's executable file
|
| 1507 | * @task: The task.
|
| 1508 | *
|
| 1509 | * Returns %NULL if task's mm (if any) has no associated executable file or
|
| 1510 | * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
|
| 1511 | * User must release file via fput().
|
| 1512 |
|
| 1513 | struct file *get_task_exe_file(struct task_struct *task)
|
| 1514 | {
|
| 1515 | struct file *exe_file = NULL;
|
| 1516 | struct mm_struct *mm;
|
| 1517 |
|
| 1518 | task_lock(task);
|
| 1519 | mm = task->mm;
|
| 1520 | if (mm) {
|
| 1521 | if (!(task->flags & PF_KTHREAD))
|
| 1522 | exe_file = get_mm_exe_file(mm);
|
| 1523 | }
|
| 1524 | task_unlock(task);
|
| 1525 | return exe_file;
|
| 1526 | }
|
| 1527 |
|
| 1528 | |
| 1529 | * get_task_mm - acquire a reference to the task's mm
|
| 1530 | * @task: The task.
|
| 1531 | *
|
| 1532 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
|
| 1533 | * this kernel workthread has transiently adopted a user mm with use_mm,
|
| 1534 | * to do its AIO) is not set and if so returns a reference to it, after
|
| 1535 | * bumping up the use count. User must release the mm via mmput()
|
| 1536 | * after use. Typically used by /proc and ptrace.
|
| 1537 |
|
| 1538 | struct mm_struct *get_task_mm(struct task_struct *task)
|
| 1539 | {
|
| 1540 | struct mm_struct *mm;
|
| 1541 |
|
| 1542 | task_lock(task);
|
| 1543 | mm = task->mm;
|
| 1544 | if (mm) {
|
| 1545 | if (task->flags & PF_KTHREAD)
|
| 1546 | mm = NULL;
|
| 1547 | else
|
| 1548 | mmget(mm);
|
| 1549 | }
|
| 1550 | task_unlock(task);
|
| 1551 | return mm;
|
| 1552 | }
|
| 1553 | EXPORT_SYMBOL_GPL(get_task_mm);
|
| 1554 |
|
| 1555 | struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
|
| 1556 | {
|
| 1557 | struct mm_struct *mm;
|
| 1558 | int err;
|
| 1559 |
|
| 1560 | err = down_read_killable(&task->signal->exec_update_lock);
|
| 1561 | if (err)
|
| 1562 | return ERR_PTR(err);
|
| 1563 |
|
| 1564 | mm = get_task_mm(task);
|
| 1565 | if (mm && mm != current->mm &&
|
| 1566 | !ptrace_may_access(task, mode)) {
|
| 1567 | mmput(mm);
|
| 1568 | mm = ERR_PTR(-EACCES);
|
| 1569 | }
|
| 1570 | up_read(&task->signal->exec_update_lock);
|
| 1571 |
|
| 1572 | return mm;
|
| 1573 | }
|
| 1574 |
|
| 1575 | static void complete_vfork_done(struct task_struct *tsk)
|
| 1576 | {
|
| 1577 | struct completion *vfork;
|
| 1578 |
|
| 1579 | task_lock(tsk);
|
| 1580 | vfork = tsk->vfork_done;
|
| 1581 | if (likely(vfork)) {
|
| 1582 | tsk->vfork_done = NULL;
|
| 1583 | complete(vfork);
|
| 1584 | }
|
| 1585 | task_unlock(tsk);
|
| 1586 | }
|
| 1587 |
|
| 1588 | static int wait_for_vfork_done(struct task_struct *child,
|
| 1589 | struct completion *vfork)
|
| 1590 | {
|
| 1591 | unsigned int state = TASK_UNINTERRUPTIBLE|TASK_KILLABLE|TASK_FREEZABLE;
|
| 1592 | int killed;
|
| 1593 |
|
| 1594 | cgroup_enter_frozen();
|
| 1595 | killed = wait_for_completion_state(vfork, state);
|
| 1596 | cgroup_leave_frozen(false);
|
| 1597 |
|
| 1598 | if (killed) {
|
| 1599 | task_lock(child);
|
| 1600 | child->vfork_done = NULL;
|
| 1601 | task_unlock(child);
|
| 1602 | }
|
| 1603 |
|
| 1604 | put_task_struct(child);
|
| 1605 | return killed;
|
| 1606 | }
|
| 1607 |
|
| 1608 | |
| 1609 | * mmput is called whenever we stop holding onto a mm_struct,
|
| 1610 | * error success whatever.
|
| 1611 | *
|
| 1612 | * mm_release is called after a mm_struct has been removed
|
| 1613 | * from the current process.
|
| 1614 | *
|
| 1615 | * This difference is important for error handling, when we
|
| 1616 | * only half set up a mm_struct for a new process and need to restore
|
| 1617 | * the old one. Because we mmput the new mm_struct before
|
| 1618 | * restoring the old one. . .
|
| 1619 | * Eric Biederman 10 January 1998
|
| 1620 |
|
| 1621 | static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
| 1622 | {
|
| 1623 | uprobe_free_utask(tsk);
|
| 1624 |
|
| 1625 |
|
| 1626 | deactivate_mm(tsk, mm);
|
| 1627 |
|
| 1628 | |
| 1629 | * Signal userspace if we're not exiting with a core dump
|
| 1630 | * because we want to leave the value intact for debugging
|
| 1631 | * purposes.
|
| 1632 |
|
| 1633 | if (tsk->clear_child_tid) {
|
| 1634 | if (atomic_read(&mm->mm_users) > 1) {
|
| 1635 | |
| 1636 | * We don't check the error code - if userspace has
|
| 1637 | * not set up a proper pointer then tough luck.
|
| 1638 |
|
| 1639 | put_user(0, tsk->clear_child_tid);
|
| 1640 | do_futex(tsk->clear_child_tid, FUTEX_WAKE,
|
| 1641 | 1, NULL, NULL, 0, 0);
|
| 1642 | }
|
| 1643 | tsk->clear_child_tid = NULL;
|
| 1644 | }
|
| 1645 |
|
| 1646 | |
| 1647 | * All done, finally we can wake up parent and return this mm to him.
|
| 1648 | * Also kthread_stop() uses this completion for synchronization.
|
| 1649 |
|
| 1650 | if (tsk->vfork_done)
|
| 1651 | complete_vfork_done(tsk);
|
| 1652 | }
|
| 1653 |
|
| 1654 | void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
| 1655 | {
|
| 1656 | futex_exit_release(tsk);
|
| 1657 | mm_release(tsk, mm);
|
| 1658 | }
|
| 1659 |
|
| 1660 | void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
| 1661 | {
|
| 1662 | futex_exec_release(tsk);
|
| 1663 | mm_release(tsk, mm);
|
| 1664 | }
|
| 1665 |
|
| 1666 | |
| 1667 | * dup_mm() - duplicates an existing mm structure
|
| 1668 | * @tsk: the task_struct with which the new mm will be associated.
|
| 1669 | * @oldmm: the mm to duplicate.
|
| 1670 | *
|
| 1671 | * Allocates a new mm structure and duplicates the provided @oldmm structure
|
| 1672 | * content into it.
|
| 1673 | *
|
| 1674 | * Return: the duplicated mm or NULL on failure.
|
| 1675 |
|
| 1676 | static struct mm_struct *dup_mm(struct task_struct *tsk,
|
| 1677 | struct mm_struct *oldmm)
|
| 1678 | {
|
| 1679 | struct mm_struct *mm;
|
| 1680 | int err;
|
| 1681 |
|
| 1682 | mm = allocate_mm();
|
| 1683 | if (!mm)
|
| 1684 | goto fail_nomem;
|
| 1685 |
|
| 1686 | memcpy(mm, oldmm, sizeof(*mm));
|
| 1687 |
|
| 1688 | if (!mm_init(mm, tsk, mm->user_ns))
|
| 1689 | goto fail_nomem;
|
| 1690 |
|
| 1691 | err = dup_mmap(mm, oldmm);
|
| 1692 | if (err)
|
| 1693 | goto free_pt;
|
| 1694 |
|
| 1695 | mm->hiwater_rss = get_mm_rss(mm);
|
| 1696 | mm->hiwater_vm = mm->total_vm;
|
| 1697 |
|
| 1698 | if (mm->binfmt && !try_module_get(mm->binfmt->module))
|
| 1699 | goto free_pt;
|
| 1700 |
|
| 1701 | return mm;
|
| 1702 |
|
| 1703 | free_pt:
|
| 1704 |
|
| 1705 | mm->binfmt = NULL;
|
| 1706 | mm_init_owner(mm, NULL);
|
| 1707 | mmput(mm);
|
| 1708 |
|
| 1709 | fail_nomem:
|
| 1710 | return NULL;
|
| 1711 | }
|
| 1712 |
|
| 1713 | static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
|
| 1714 | {
|
| 1715 | struct mm_struct *mm, *oldmm;
|
| 1716 |
|
| 1717 | tsk->min_flt = tsk->maj_flt = 0;
|
| 1718 | tsk->nvcsw = tsk->nivcsw = 0;
|
| 1719 | #ifdef CONFIG_DETECT_HUNG_TASK
|
| 1720 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
|
| 1721 | tsk->last_switch_time = 0;
|
| 1722 | #endif
|
| 1723 |
|
| 1724 | tsk->mm = NULL;
|
| 1725 | tsk->active_mm = NULL;
|
| 1726 |
|
| 1727 | |
| 1728 | * Are we cloning a kernel thread?
|
| 1729 | *
|
| 1730 | * We need to steal a active VM for that..
|
| 1731 |
|
| 1732 | oldmm = current->mm;
|
| 1733 | if (!oldmm)
|
| 1734 | return 0;
|
| 1735 |
|
| 1736 | if (clone_flags & CLONE_VM) {
|
| 1737 | mmget(oldmm);
|
| 1738 | mm = oldmm;
|
| 1739 | } else {
|
| 1740 | mm = dup_mm(tsk, current->mm);
|
| 1741 | if (!mm)
|
| 1742 | return -ENOMEM;
|
| 1743 | }
|
| 1744 |
|
| 1745 | tsk->mm = mm;
|
| 1746 | tsk->active_mm = mm;
|
| 1747 | sched_mm_cid_fork(tsk);
|
| 1748 | return 0;
|
| 1749 | }
|
| 1750 |
|
| 1751 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
|
| 1752 | {
|
| 1753 | struct fs_struct *fs = current->fs;
|
| 1754 | if (clone_flags & CLONE_FS) {
|
| 1755 |
|
| 1756 | spin_lock(&fs->lock);
|
| 1757 | if (fs->in_exec) {
|
| 1758 | spin_unlock(&fs->lock);
|
| 1759 | return -EAGAIN;
|
| 1760 | }
|
| 1761 | fs->users++;
|
| 1762 | spin_unlock(&fs->lock);
|
| 1763 | return 0;
|
| 1764 | }
|
| 1765 | tsk->fs = copy_fs_struct(fs);
|
| 1766 | if (!tsk->fs)
|
| 1767 | return -ENOMEM;
|
| 1768 | return 0;
|
| 1769 | }
|
| 1770 |
|
| 1771 | static int copy_files(unsigned long clone_flags, struct task_struct *tsk,
|
| 1772 | int no_files)
|
| 1773 | {
|
| 1774 | struct files_struct *oldf, *newf;
|
| 1775 | int error = 0;
|
| 1776 |
|
| 1777 | |
| 1778 | * A background process may not have any files ...
|
| 1779 |
|
| 1780 | oldf = current->files;
|
| 1781 | if (!oldf)
|
| 1782 | goto out;
|
| 1783 |
|
| 1784 | if (no_files) {
|
| 1785 | tsk->files = NULL;
|
| 1786 | goto out;
|
| 1787 | }
|
| 1788 |
|
| 1789 | if (clone_flags & CLONE_FILES) {
|
| 1790 | atomic_inc(&oldf->count);
|
| 1791 | goto out;
|
| 1792 | }
|
| 1793 |
|
| 1794 | newf = dup_fd(oldf, NR_OPEN_MAX, &error);
|
| 1795 | if (!newf)
|
| 1796 | goto out;
|
| 1797 |
|
| 1798 | tsk->files = newf;
|
| 1799 | error = 0;
|
| 1800 | out:
|
| 1801 | return error;
|
| 1802 | }
|
| 1803 |
|
| 1804 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
|
| 1805 | {
|
| 1806 | struct sighand_struct *sig;
|
| 1807 |
|
| 1808 | if (clone_flags & CLONE_SIGHAND) {
|
| 1809 | refcount_inc(¤t->sighand->count);
|
| 1810 | return 0;
|
| 1811 | }
|
| 1812 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
|
| 1813 | RCU_INIT_POINTER(tsk->sighand, sig);
|
| 1814 | if (!sig)
|
| 1815 | return -ENOMEM;
|
| 1816 |
|
| 1817 | refcount_set(&sig->count, 1);
|
| 1818 | spin_lock_irq(¤t->sighand->siglock);
|
| 1819 | memcpy(sig->action, current->sighand->action, sizeof(sig->action));
|
| 1820 | spin_unlock_irq(¤t->sighand->siglock);
|
| 1821 |
|
| 1822 |
|
| 1823 | if (clone_flags & CLONE_CLEAR_SIGHAND)
|
| 1824 | flush_signal_handlers(tsk, 0);
|
| 1825 |
|
| 1826 | return 0;
|
| 1827 | }
|
| 1828 |
|
| 1829 | void __cleanup_sighand(struct sighand_struct *sighand)
|
| 1830 | {
|
| 1831 | if (refcount_dec_and_test(&sighand->count)) {
|
| 1832 | signalfd_cleanup(sighand);
|
| 1833 | |
| 1834 | * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
|
| 1835 | * without an RCU grace period, see __lock_task_sighand().
|
| 1836 |
|
| 1837 | kmem_cache_free(sighand_cachep, sighand);
|
| 1838 | }
|
| 1839 | }
|
| 1840 |
|
| 1841 | |
| 1842 | * Initialize POSIX timer handling for a thread group.
|
| 1843 |
|
| 1844 | static void posix_cpu_timers_init_group(struct signal_struct *sig)
|
| 1845 | {
|
| 1846 | struct posix_cputimers *pct = &sig->posix_cputimers;
|
| 1847 | unsigned long cpu_limit;
|
| 1848 |
|
| 1849 | cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
|
| 1850 | posix_cputimers_group_init(pct, cpu_limit);
|
| 1851 | }
|
| 1852 |
|
| 1853 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
|
| 1854 | {
|
| 1855 | struct signal_struct *sig;
|
| 1856 |
|
| 1857 | if (clone_flags & CLONE_THREAD)
|
| 1858 | return 0;
|
| 1859 |
|
| 1860 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
|
| 1861 | tsk->signal = sig;
|
| 1862 | if (!sig)
|
| 1863 | return -ENOMEM;
|
| 1864 |
|
| 1865 | sig->nr_threads = 1;
|
| 1866 | sig->quick_threads = 1;
|
| 1867 | atomic_set(&sig->live, 1);
|
| 1868 | refcount_set(&sig->sigcnt, 1);
|
| 1869 |
|
| 1870 |
|
| 1871 | sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
|
| 1872 | tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
|
| 1873 |
|
| 1874 | init_waitqueue_head(&sig->wait_chldexit);
|
| 1875 | sig->curr_target = tsk;
|
| 1876 | init_sigpending(&sig->shared_pending);
|
| 1877 | INIT_HLIST_HEAD(&sig->multiprocess);
|
| 1878 | seqlock_init(&sig->stats_lock);
|
| 1879 | prev_cputime_init(&sig->prev_cputime);
|
| 1880 |
|
| 1881 | #ifdef CONFIG_POSIX_TIMERS
|
| 1882 | INIT_LIST_HEAD(&sig->posix_timers);
|
| 1883 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
| 1884 | sig->real_timer.function = it_real_fn;
|
| 1885 | #endif
|
| 1886 |
|
| 1887 | task_lock(current->group_leader);
|
| 1888 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
|
| 1889 | task_unlock(current->group_leader);
|
| 1890 |
|
| 1891 | posix_cpu_timers_init_group(sig);
|
| 1892 |
|
| 1893 | tty_audit_fork(sig);
|
| 1894 | sched_autogroup_fork(sig);
|
| 1895 |
|
| 1896 | sig->oom_score_adj = current->signal->oom_score_adj;
|
| 1897 | sig->oom_score_adj_min = current->signal->oom_score_adj_min;
|
| 1898 |
|
| 1899 | mutex_init(&sig->cred_guard_mutex);
|
| 1900 | init_rwsem(&sig->exec_update_lock);
|
| 1901 |
|
| 1902 | return 0;
|
| 1903 | }
|
| 1904 |
|
| 1905 | static void copy_seccomp(struct task_struct *p)
|
| 1906 | {
|
| 1907 | #ifdef CONFIG_SECCOMP
|
| 1908 | |
| 1909 | * Must be called with sighand->lock held, which is common to
|
| 1910 | * all threads in the group. Holding cred_guard_mutex is not
|
| 1911 | * needed because this new task is not yet running and cannot
|
| 1912 | * be racing exec.
|
| 1913 |
|
| 1914 | assert_spin_locked(¤t->sighand->siglock);
|
| 1915 |
|
| 1916 |
|
| 1917 | get_seccomp_filter(current);
|
| 1918 | p->seccomp = current->seccomp;
|
| 1919 |
|
| 1920 | |
| 1921 | * Explicitly enable no_new_privs here in case it got set
|
| 1922 | * between the task_struct being duplicated and holding the
|
| 1923 | * sighand lock. The seccomp state and nnp must be in sync.
|
| 1924 |
|
| 1925 | if (task_no_new_privs(current))
|
| 1926 | task_set_no_new_privs(p);
|
| 1927 |
|
| 1928 | |
| 1929 | * If the parent gained a seccomp mode after copying thread
|
| 1930 | * flags and between before we held the sighand lock, we have
|
| 1931 | * to manually enable the seccomp thread flag here.
|
| 1932 |
|
| 1933 | if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
|
| 1934 | set_task_syscall_work(p, SECCOMP);
|
| 1935 | #endif
|
| 1936 | }
|
| 1937 |
|
| 1938 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
|
| 1939 | {
|
| 1940 | current->clear_child_tid = tidptr;
|
| 1941 |
|
| 1942 | return task_pid_vnr(current);
|
| 1943 | }
|
| 1944 |
|
| 1945 | static void rt_mutex_init_task(struct task_struct *p)
|
| 1946 | {
|
| 1947 | raw_spin_lock_init(&p->pi_lock);
|
| 1948 | #ifdef CONFIG_RT_MUTEXES
|
| 1949 | p->pi_waiters = RB_ROOT_CACHED;
|
| 1950 | p->pi_top_task = NULL;
|
| 1951 | p->pi_blocked_on = NULL;
|
| 1952 | #endif
|
| 1953 | }
|
| 1954 |
|
| 1955 | static inline void init_task_pid_links(struct task_struct *task)
|
| 1956 | {
|
| 1957 | enum pid_type type;
|
| 1958 |
|
| 1959 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
|
| 1960 | INIT_HLIST_NODE(&task->pid_links[type]);
|
| 1961 | }
|
| 1962 |
|
| 1963 | static inline void
|
| 1964 | init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
|
| 1965 | {
|
| 1966 | if (type == PIDTYPE_PID)
|
| 1967 | task->thread_pid = pid;
|
| 1968 | else
|
| 1969 | task->signal->pids[type] = pid;
|
| 1970 | }
|
| 1971 |
|
| 1972 | static inline void rcu_copy_process(struct task_struct *p)
|
| 1973 | {
|
| 1974 | #ifdef CONFIG_PREEMPT_RCU
|
| 1975 | p->rcu_read_lock_nesting = 0;
|
| 1976 | p->rcu_read_unlock_special.s = 0;
|
| 1977 | p->rcu_blocked_node = NULL;
|
| 1978 | INIT_LIST_HEAD(&p->rcu_node_entry);
|
| 1979 | #endif
|
| 1980 | #ifdef CONFIG_TASKS_RCU
|
| 1981 | p->rcu_tasks_holdout = false;
|
| 1982 | INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
|
| 1983 | p->rcu_tasks_idle_cpu = -1;
|
| 1984 | #endif
|
| 1985 | #ifdef CONFIG_TASKS_TRACE_RCU
|
| 1986 | p->trc_reader_nesting = 0;
|
| 1987 | p->trc_reader_special.s = 0;
|
| 1988 | INIT_LIST_HEAD(&p->trc_holdout_list);
|
| 1989 | INIT_LIST_HEAD(&p->trc_blkd_node);
|
| 1990 | #endif
|
| 1991 | }
|
| 1992 |
|
| 1993 | struct pid *pidfd_pid(const struct file *file)
|
| 1994 | {
|
| 1995 | if (file->f_op == &pidfd_fops)
|
| 1996 | return file->private_data;
|
| 1997 |
|
| 1998 | return ERR_PTR(-EBADF);
|
| 1999 | }
|
| 2000 |
|
| 2001 | static int pidfd_release(struct inode *inode, struct file *file)
|
| 2002 | {
|
| 2003 | struct pid *pid = file->private_data;
|
| 2004 |
|
| 2005 | file->private_data = NULL;
|
| 2006 | put_pid(pid);
|
| 2007 | return 0;
|
| 2008 | }
|
| 2009 |
|
| 2010 | #ifdef CONFIG_PROC_FS
|
| 2011 | |
| 2012 | * pidfd_show_fdinfo - print information about a pidfd
|
| 2013 | * @m: proc fdinfo file
|
| 2014 | * @f: file referencing a pidfd
|
| 2015 | *
|
| 2016 | * Pid:
|
| 2017 | * This function will print the pid that a given pidfd refers to in the
|
| 2018 | * pid namespace of the procfs instance.
|
| 2019 | * If the pid namespace of the process is not a descendant of the pid
|
| 2020 | * namespace of the procfs instance 0 will be shown as its pid. This is
|
| 2021 | * similar to calling getppid() on a process whose parent is outside of
|
| 2022 | * its pid namespace.
|
| 2023 | *
|
| 2024 | * NSpid:
|
| 2025 | * If pid namespaces are supported then this function will also print
|
| 2026 | * the pid of a given pidfd refers to for all descendant pid namespaces
|
| 2027 | * starting from the current pid namespace of the instance, i.e. the
|
| 2028 | * Pid field and the first entry in the NSpid field will be identical.
|
| 2029 | * If the pid namespace of the process is not a descendant of the pid
|
| 2030 | * namespace of the procfs instance 0 will be shown as its first NSpid
|
| 2031 | * entry and no others will be shown.
|
| 2032 | * Note that this differs from the Pid and NSpid fields in
|
| 2033 | * /proc/<pid>/status where Pid and NSpid are always shown relative to
|
| 2034 | * the pid namespace of the procfs instance. The difference becomes
|
| 2035 | * obvious when sending around a pidfd between pid namespaces from a
|
| 2036 | * different branch of the tree, i.e. where no ancestral relation is
|
| 2037 | * present between the pid namespaces:
|
| 2038 | * - create two new pid namespaces ns1 and ns2 in the initial pid
|
| 2039 | * namespace (also take care to create new mount namespaces in the
|
| 2040 | * new pid namespace and mount procfs)
|
| 2041 | * - create a process with a pidfd in ns1
|
| 2042 | * - send pidfd from ns1 to ns2
|
| 2043 | * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
|
| 2044 | * have exactly one entry, which is 0
|
| 2045 |
|
| 2046 | static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
|
| 2047 | {
|
| 2048 | struct pid *pid = f->private_data;
|
| 2049 | struct pid_namespace *ns;
|
| 2050 | pid_t nr = -1;
|
| 2051 |
|
| 2052 | if (likely(pid_has_task(pid, PIDTYPE_PID))) {
|
| 2053 | ns = proc_pid_ns(file_inode(m->file)->i_sb);
|
| 2054 | nr = pid_nr_ns(pid, ns);
|
| 2055 | }
|
| 2056 |
|
| 2057 | seq_put_decimal_ll(m, "Pid:\t", nr);
|
| 2058 |
|
| 2059 | #ifdef CONFIG_PID_NS
|
| 2060 | seq_put_decimal_ll(m, "\nNSpid:\t", nr);
|
| 2061 | if (nr > 0) {
|
| 2062 | int i;
|
| 2063 |
|
| 2064 | |
| 2065 | * ns, i.e. the pid namespace associated with the procfs
|
| 2066 | * instance, is in the pid namespace hierarchy of pid.
|
| 2067 | * Start at one below the already printed level.
|
| 2068 |
|
| 2069 | for (i = ns->level + 1; i <= pid->level; i++)
|
| 2070 | seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
|
| 2071 | }
|
| 2072 | #endif
|
| 2073 | seq_putc(m, '\n');
|
| 2074 | }
|
| 2075 | #endif
|
| 2076 |
|
| 2077 | |
| 2078 | * Poll support for process exit notification.
|
| 2079 |
|
| 2080 | static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
|
| 2081 | {
|
| 2082 | struct pid *pid = file->private_data;
|
| 2083 | __poll_t poll_flags = 0;
|
| 2084 |
|
| 2085 | poll_wait(file, &pid->wait_pidfd, pts);
|
| 2086 |
|
| 2087 | |
| 2088 | * Inform pollers only when the whole thread group exits.
|
| 2089 | * If the thread group leader exits before all other threads in the
|
| 2090 | * group, then poll(2) should block, similar to the wait(2) family.
|
| 2091 |
|
| 2092 | if (thread_group_exited(pid))
|
| 2093 | poll_flags = EPOLLIN | EPOLLRDNORM;
|
| 2094 |
|
| 2095 | return poll_flags;
|
| 2096 | }
|
| 2097 |
|
| 2098 | const struct file_operations pidfd_fops = {
|
| 2099 | .release = pidfd_release,
|
| 2100 | .poll = pidfd_poll,
|
| 2101 | #ifdef CONFIG_PROC_FS
|
| 2102 | .show_fdinfo = pidfd_show_fdinfo,
|
| 2103 | #endif
|
| 2104 | };
|
| 2105 |
|
| 2106 | |
| 2107 | * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
|
| 2108 | * @pid: the struct pid for which to create a pidfd
|
| 2109 | * @flags: flags of the new @pidfd
|
| 2110 | * @ret: Where to return the file for the pidfd.
|
| 2111 | *
|
| 2112 | * Allocate a new file that stashes @pid and reserve a new pidfd number in the
|
| 2113 | * caller's file descriptor table. The pidfd is reserved but not installed yet.
|
| 2114 | *
|
| 2115 | * The helper doesn't perform checks on @pid which makes it useful for pidfds
|
| 2116 | * created via CLONE_PIDFD where @pid has no task attached when the pidfd and
|
| 2117 | * pidfd file are prepared.
|
| 2118 | *
|
| 2119 | * If this function returns successfully the caller is responsible to either
|
| 2120 | * call fd_install() passing the returned pidfd and pidfd file as arguments in
|
| 2121 | * order to install the pidfd into its file descriptor table or they must use
|
| 2122 | * put_unused_fd() and fput() on the returned pidfd and pidfd file
|
| 2123 | * respectively.
|
| 2124 | *
|
| 2125 | * This function is useful when a pidfd must already be reserved but there
|
| 2126 | * might still be points of failure afterwards and the caller wants to ensure
|
| 2127 | * that no pidfd is leaked into its file descriptor table.
|
| 2128 | *
|
| 2129 | * Return: On success, a reserved pidfd is returned from the function and a new
|
| 2130 | * pidfd file is returned in the last argument to the function. On
|
| 2131 | * error, a negative error code is returned from the function and the
|
| 2132 | * last argument remains unchanged.
|
| 2133 |
|
| 2134 | static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
|
| 2135 | {
|
| 2136 | int pidfd;
|
| 2137 | struct file *pidfd_file;
|
| 2138 |
|
| 2139 | if (flags & ~(O_NONBLOCK | O_RDWR | O_CLOEXEC))
|
| 2140 | return -EINVAL;
|
| 2141 |
|
| 2142 | pidfd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
|
| 2143 | if (pidfd < 0)
|
| 2144 | return pidfd;
|
| 2145 |
|
| 2146 | pidfd_file = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
|
| 2147 | flags | O_RDWR | O_CLOEXEC);
|
| 2148 | if (IS_ERR(pidfd_file)) {
|
| 2149 | put_unused_fd(pidfd);
|
| 2150 | return PTR_ERR(pidfd_file);
|
| 2151 | }
|
| 2152 | get_pid(pid);
|
| 2153 | *ret = pidfd_file;
|
| 2154 | return pidfd;
|
| 2155 | }
|
| 2156 |
|
| 2157 | |
| 2158 | * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
|
| 2159 | * @pid: the struct pid for which to create a pidfd
|
| 2160 | * @flags: flags of the new @pidfd
|
| 2161 | * @ret: Where to return the pidfd.
|
| 2162 | *
|
| 2163 | * Allocate a new file that stashes @pid and reserve a new pidfd number in the
|
| 2164 | * caller's file descriptor table. The pidfd is reserved but not installed yet.
|
| 2165 | *
|
| 2166 | * The helper verifies that @pid is used as a thread group leader.
|
| 2167 | *
|
| 2168 | * If this function returns successfully the caller is responsible to either
|
| 2169 | * call fd_install() passing the returned pidfd and pidfd file as arguments in
|
| 2170 | * order to install the pidfd into its file descriptor table or they must use
|
| 2171 | * put_unused_fd() and fput() on the returned pidfd and pidfd file
|
| 2172 | * respectively.
|
| 2173 | *
|
| 2174 | * This function is useful when a pidfd must already be reserved but there
|
| 2175 | * might still be points of failure afterwards and the caller wants to ensure
|
| 2176 | * that no pidfd is leaked into its file descriptor table.
|
| 2177 | *
|
| 2178 | * Return: On success, a reserved pidfd is returned from the function and a new
|
| 2179 | * pidfd file is returned in the last argument to the function. On
|
| 2180 | * error, a negative error code is returned from the function and the
|
| 2181 | * last argument remains unchanged.
|
| 2182 |
|
| 2183 | int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
|
| 2184 | {
|
| 2185 | if (!pid || !pid_has_task(pid, PIDTYPE_TGID))
|
| 2186 | return -EINVAL;
|
| 2187 |
|
| 2188 | return __pidfd_prepare(pid, flags, ret);
|
| 2189 | }
|
| 2190 |
|
| 2191 | static void __delayed_free_task(struct rcu_head *rhp)
|
| 2192 | {
|
| 2193 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
|
| 2194 |
|
| 2195 | free_task(tsk);
|
| 2196 | }
|
| 2197 |
|
| 2198 | static __always_inline void delayed_free_task(struct task_struct *tsk)
|
| 2199 | {
|
| 2200 | if (IS_ENABLED(CONFIG_MEMCG))
|
| 2201 | call_rcu(&tsk->rcu, __delayed_free_task);
|
| 2202 | else
|
| 2203 | free_task(tsk);
|
| 2204 | }
|
| 2205 |
|
| 2206 | static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
|
| 2207 | {
|
| 2208 |
|
| 2209 | if (!tsk->mm)
|
| 2210 | return;
|
| 2211 |
|
| 2212 |
|
| 2213 | if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
|
| 2214 | return;
|
| 2215 |
|
| 2216 |
|
| 2217 | mutex_lock(&oom_adj_mutex);
|
| 2218 | set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
|
| 2219 |
|
| 2220 | tsk->signal->oom_score_adj = current->signal->oom_score_adj;
|
| 2221 | tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
|
| 2222 | mutex_unlock(&oom_adj_mutex);
|
| 2223 | }
|
| 2224 |
|
| 2225 | #ifdef CONFIG_RV
|
| 2226 | static void rv_task_fork(struct task_struct *p)
|
| 2227 | {
|
| 2228 | int i;
|
| 2229 |
|
| 2230 | for (i = 0; i < RV_PER_TASK_MONITORS; i++)
|
| 2231 | p->rv[i].da_mon.monitoring = false;
|
| 2232 | }
|
| 2233 | #else
|
| 2234 | #define rv_task_fork(p) do {} while (0)
|
| 2235 | #endif
|
| 2236 |
|
| 2237 | |
| 2238 | * This creates a new process as a copy of the old one,
|
| 2239 | * but does not actually start it yet.
|
| 2240 | *
|
| 2241 | * It copies the registers, and all the appropriate
|
| 2242 | * parts of the process environment (as per the clone
|
| 2243 | * flags). The actual kick-off is left to the caller.
|
| 2244 |
|
| 2245 | __latent_entropy struct task_struct *copy_process(
|
| 2246 | struct pid *pid,
|
| 2247 | int trace,
|
| 2248 | int node,
|
| 2249 | struct kernel_clone_args *args)
|
| 2250 | {
|
| 2251 | int pidfd = -1, retval;
|
| 2252 | struct task_struct *p;
|
| 2253 | struct multiprocess_signals delayed;
|
| 2254 | struct file *pidfile = NULL;
|
| 2255 | const u64 clone_flags = args->flags;
|
| 2256 | struct nsproxy *nsp = current->nsproxy;
|
| 2257 |
|
| 2258 | |
| 2259 | * Don't allow sharing the root directory with processes in a different
|
| 2260 | * namespace
|
| 2261 |
|
| 2262 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
|
| 2263 | return ERR_PTR(-EINVAL);
|
| 2264 |
|
| 2265 | if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
|
| 2266 | return ERR_PTR(-EINVAL);
|
| 2267 |
|
| 2268 | |
| 2269 | * Thread groups must share signals as well, and detached threads
|
| 2270 | * can only be started up within the thread group.
|
| 2271 |
|
| 2272 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
|
| 2273 | return ERR_PTR(-EINVAL);
|
| 2274 |
|
| 2275 | |
| 2276 | * Shared signal handlers imply shared VM. By way of the above,
|
| 2277 | * thread groups also imply shared VM. Blocking this case allows
|
| 2278 | * for various simplifications in other code.
|
| 2279 |
|
| 2280 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
|
| 2281 | return ERR_PTR(-EINVAL);
|
| 2282 |
|
| 2283 | |
| 2284 | * Siblings of global init remain as zombies on exit since they are
|
| 2285 | * not reaped by their parent (swapper). To solve this and to avoid
|
| 2286 | * multi-rooted process trees, prevent global and container-inits
|
| 2287 | * from creating siblings.
|
| 2288 |
|
| 2289 | if ((clone_flags & CLONE_PARENT) &&
|
| 2290 | current->signal->flags & SIGNAL_UNKILLABLE)
|
| 2291 | return ERR_PTR(-EINVAL);
|
| 2292 |
|
| 2293 | |
| 2294 | * If the new process will be in a different pid or user namespace
|
| 2295 | * do not allow it to share a thread group with the forking task.
|
| 2296 |
|
| 2297 | if (clone_flags & CLONE_THREAD) {
|
| 2298 | if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
|
| 2299 | (task_active_pid_ns(current) != nsp->pid_ns_for_children))
|
| 2300 | return ERR_PTR(-EINVAL);
|
| 2301 | }
|
| 2302 |
|
| 2303 | if (clone_flags & CLONE_PIDFD) {
|
| 2304 | |
| 2305 | * - CLONE_DETACHED is blocked so that we can potentially
|
| 2306 | * reuse it later for CLONE_PIDFD.
|
| 2307 | * - CLONE_THREAD is blocked until someone really needs it.
|
| 2308 |
|
| 2309 | if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
|
| 2310 | return ERR_PTR(-EINVAL);
|
| 2311 | }
|
| 2312 |
|
| 2313 | |
| 2314 | * Force any signals received before this point to be delivered
|
| 2315 | * before the fork happens. Collect up signals sent to multiple
|
| 2316 | * processes that happen during the fork and delay them so that
|
| 2317 | * they appear to happen after the fork.
|
| 2318 |
|
| 2319 | sigemptyset(&delayed.signal);
|
| 2320 | INIT_HLIST_NODE(&delayed.node);
|
| 2321 |
|
| 2322 | spin_lock_irq(¤t->sighand->siglock);
|
| 2323 | if (!(clone_flags & CLONE_THREAD))
|
| 2324 | hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
|
| 2325 | recalc_sigpending();
|
| 2326 | spin_unlock_irq(¤t->sighand->siglock);
|
| 2327 | retval = -ERESTARTNOINTR;
|
| 2328 | if (task_sigpending(current))
|
| 2329 | goto fork_out;
|
| 2330 |
|
| 2331 | retval = -ENOMEM;
|
| 2332 | p = dup_task_struct(current, node);
|
| 2333 | if (!p)
|
| 2334 | goto fork_out;
|
| 2335 | p->flags &= ~PF_KTHREAD;
|
| 2336 | if (args->kthread)
|
| 2337 | p->flags |= PF_KTHREAD;
|
| 2338 | if (args->user_worker) {
|
| 2339 | |
| 2340 | * Mark us a user worker, and block any signal that isn't
|
| 2341 | * fatal or STOP
|
| 2342 |
|
| 2343 | p->flags |= PF_USER_WORKER;
|
| 2344 | siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
|
| 2345 | }
|
| 2346 | if (args->io_thread)
|
| 2347 | p->flags |= PF_IO_WORKER;
|
| 2348 |
|
| 2349 | if (args->name)
|
| 2350 | strscpy_pad(p->comm, args->name, sizeof(p->comm));
|
| 2351 |
|
| 2352 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
|
| 2353 | |
| 2354 | * Clear TID on mm_release()?
|
| 2355 |
|
| 2356 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
|
| 2357 |
|
| 2358 | ftrace_graph_init_task(p);
|
| 2359 |
|
| 2360 | rt_mutex_init_task(p);
|
| 2361 |
|
| 2362 | lockdep_assert_irqs_enabled();
|
| 2363 | #ifdef CONFIG_PROVE_LOCKING
|
| 2364 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
|
| 2365 | #endif
|
| 2366 | retval = copy_creds(p, clone_flags);
|
| 2367 | if (retval < 0)
|
| 2368 | goto bad_fork_free;
|
| 2369 |
|
| 2370 | retval = -EAGAIN;
|
| 2371 | if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
|
| 2372 | if (p->real_cred->user != INIT_USER &&
|
| 2373 | !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
|
| 2374 | goto bad_fork_cleanup_count;
|
| 2375 | }
|
| 2376 | current->flags &= ~PF_NPROC_EXCEEDED;
|
| 2377 |
|
| 2378 | |
| 2379 | * If multiple threads are within copy_process(), then this check
|
| 2380 | * triggers too late. This doesn't hurt, the check is only there
|
| 2381 | * to stop root fork bombs.
|
| 2382 |
|
| 2383 | retval = -EAGAIN;
|
| 2384 | if (data_race(nr_threads >= max_threads))
|
| 2385 | goto bad_fork_cleanup_count;
|
| 2386 |
|
| 2387 | delayacct_tsk_init(p);
|
| 2388 | p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
|
| 2389 | p->flags |= PF_FORKNOEXEC;
|
| 2390 | INIT_LIST_HEAD(&p->children);
|
| 2391 | INIT_LIST_HEAD(&p->sibling);
|
| 2392 | rcu_copy_process(p);
|
| 2393 | p->vfork_done = NULL;
|
| 2394 | spin_lock_init(&p->alloc_lock);
|
| 2395 |
|
| 2396 | init_sigpending(&p->pending);
|
| 2397 |
|
| 2398 | p->utime = p->stime = p->gtime = 0;
|
| 2399 | #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
|
| 2400 | p->utimescaled = p->stimescaled = 0;
|
| 2401 | #endif
|
| 2402 | prev_cputime_init(&p->prev_cputime);
|
| 2403 |
|
| 2404 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
|
| 2405 | seqcount_init(&p->vtime.seqcount);
|
| 2406 | p->vtime.starttime = 0;
|
| 2407 | p->vtime.state = VTIME_INACTIVE;
|
| 2408 | #endif
|
| 2409 |
|
| 2410 | #ifdef CONFIG_IO_URING
|
| 2411 | p->io_uring = NULL;
|
| 2412 | #endif
|
| 2413 |
|
| 2414 | p->default_timer_slack_ns = current->timer_slack_ns;
|
| 2415 |
|
| 2416 | #ifdef CONFIG_PSI
|
| 2417 | p->psi_flags = 0;
|
| 2418 | #endif
|
| 2419 |
|
| 2420 | task_io_accounting_init(&p->ioac);
|
| 2421 | acct_clear_integrals(p);
|
| 2422 |
|
| 2423 | posix_cputimers_init(&p->posix_cputimers);
|
| 2424 |
|
| 2425 | p->io_context = NULL;
|
| 2426 | audit_set_context(p, NULL);
|
| 2427 | cgroup_fork(p);
|
| 2428 | if (args->kthread) {
|
| 2429 | if (!set_kthread_struct(p))
|
| 2430 | goto bad_fork_cleanup_delayacct;
|
| 2431 | }
|
| 2432 | #ifdef CONFIG_NUMA
|
| 2433 | p->mempolicy = mpol_dup(p->mempolicy);
|
| 2434 | if (IS_ERR(p->mempolicy)) {
|
| 2435 | retval = PTR_ERR(p->mempolicy);
|
| 2436 | p->mempolicy = NULL;
|
| 2437 | goto bad_fork_cleanup_delayacct;
|
| 2438 | }
|
| 2439 | #endif
|
| 2440 | #ifdef CONFIG_CPUSETS
|
| 2441 | p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
|
| 2442 | p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
|
| 2443 | seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
|
| 2444 | #endif
|
| 2445 | #ifdef CONFIG_TRACE_IRQFLAGS
|
| 2446 | memset(&p->irqtrace, 0, sizeof(p->irqtrace));
|
| 2447 | p->irqtrace.hardirq_disable_ip = _THIS_IP_;
|
| 2448 | p->irqtrace.softirq_enable_ip = _THIS_IP_;
|
| 2449 | p->softirqs_enabled = 1;
|
| 2450 | p->softirq_context = 0;
|
| 2451 | #endif
|
| 2452 |
|
| 2453 | p->pagefault_disabled = 0;
|
| 2454 |
|
| 2455 | #ifdef CONFIG_LOCKDEP
|
| 2456 | lockdep_init_task(p);
|
| 2457 | #endif
|
| 2458 |
|
| 2459 | #ifdef CONFIG_DEBUG_MUTEXES
|
| 2460 | p->blocked_on = NULL;
|
| 2461 | #endif
|
| 2462 | #ifdef CONFIG_BCACHE
|
| 2463 | p->sequential_io = 0;
|
| 2464 | p->sequential_io_avg = 0;
|
| 2465 | #endif
|
| 2466 | #ifdef CONFIG_BPF_SYSCALL
|
| 2467 | RCU_INIT_POINTER(p->bpf_storage, NULL);
|
| 2468 | p->bpf_ctx = NULL;
|
| 2469 | #endif
|
| 2470 |
|
| 2471 |
|
| 2472 | retval = sched_fork(clone_flags, p);
|
| 2473 | if (retval)
|
| 2474 | goto bad_fork_cleanup_policy;
|
| 2475 |
|
| 2476 | retval = perf_event_init_task(p, clone_flags);
|
| 2477 | if (retval)
|
| 2478 | goto bad_fork_cleanup_policy;
|
| 2479 | retval = audit_alloc(p);
|
| 2480 | if (retval)
|
| 2481 | goto bad_fork_cleanup_perf;
|
| 2482 |
|
| 2483 | shm_init_task(p);
|
| 2484 | retval = security_task_alloc(p, clone_flags);
|
| 2485 | if (retval)
|
| 2486 | goto bad_fork_cleanup_audit;
|
| 2487 | retval = copy_semundo(clone_flags, p);
|
| 2488 | if (retval)
|
| 2489 | goto bad_fork_cleanup_security;
|
| 2490 | retval = copy_files(clone_flags, p, args->no_files);
|
| 2491 | if (retval)
|
| 2492 | goto bad_fork_cleanup_semundo;
|
| 2493 | retval = copy_fs(clone_flags, p);
|
| 2494 | if (retval)
|
| 2495 | goto bad_fork_cleanup_files;
|
| 2496 | retval = copy_sighand(clone_flags, p);
|
| 2497 | if (retval)
|
| 2498 | goto bad_fork_cleanup_fs;
|
| 2499 | retval = copy_signal(clone_flags, p);
|
| 2500 | if (retval)
|
| 2501 | goto bad_fork_cleanup_sighand;
|
| 2502 | retval = copy_mm(clone_flags, p);
|
| 2503 | if (retval)
|
| 2504 | goto bad_fork_cleanup_signal;
|
| 2505 | retval = copy_namespaces(clone_flags, p);
|
| 2506 | if (retval)
|
| 2507 | goto bad_fork_cleanup_mm;
|
| 2508 | retval = copy_io(clone_flags, p);
|
| 2509 | if (retval)
|
| 2510 | goto bad_fork_cleanup_namespaces;
|
| 2511 | retval = copy_thread(p, args);
|
| 2512 | if (retval)
|
| 2513 | goto bad_fork_cleanup_io;
|
| 2514 |
|
| 2515 | stackleak_task_init(p);
|
| 2516 |
|
| 2517 | if (pid != &init_struct_pid) {
|
| 2518 | pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
|
| 2519 | args->set_tid_size);
|
| 2520 | if (IS_ERR(pid)) {
|
| 2521 | retval = PTR_ERR(pid);
|
| 2522 | goto bad_fork_cleanup_thread;
|
| 2523 | }
|
| 2524 | }
|
| 2525 |
|
| 2526 | |
| 2527 | * This has to happen after we've potentially unshared the file
|
| 2528 | * descriptor table (so that the pidfd doesn't leak into the child
|
| 2529 | * if the fd table isn't shared).
|
| 2530 |
|
| 2531 | if (clone_flags & CLONE_PIDFD) {
|
| 2532 |
|
| 2533 | retval = __pidfd_prepare(pid, O_RDWR | O_CLOEXEC, &pidfile);
|
| 2534 | if (retval < 0)
|
| 2535 | goto bad_fork_free_pid;
|
| 2536 | pidfd = retval;
|
| 2537 |
|
| 2538 | retval = put_user(pidfd, args->pidfd);
|
| 2539 | if (retval)
|
| 2540 | goto bad_fork_put_pidfd;
|
| 2541 | }
|
| 2542 |
|
| 2543 | #ifdef CONFIG_BLOCK
|
| 2544 | p->plug = NULL;
|
| 2545 | #endif
|
| 2546 | futex_init_task(p);
|
| 2547 |
|
| 2548 | |
| 2549 | * sigaltstack should be cleared when sharing the same VM
|
| 2550 |
|
| 2551 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
|
| 2552 | sas_ss_reset(p);
|
| 2553 |
|
| 2554 | |
| 2555 | * Syscall tracing and stepping should be turned off in the
|
| 2556 | * child regardless of CLONE_PTRACE.
|
| 2557 |
|
| 2558 | user_disable_single_step(p);
|
| 2559 | clear_task_syscall_work(p, SYSCALL_TRACE);
|
| 2560 | #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
|
| 2561 | clear_task_syscall_work(p, SYSCALL_EMU);
|
| 2562 | #endif
|
| 2563 | clear_tsk_latency_tracing(p);
|
| 2564 |
|
| 2565 |
|
| 2566 | p->pid = pid_nr(pid);
|
| 2567 | if (clone_flags & CLONE_THREAD) {
|
| 2568 | p->group_leader = current->group_leader;
|
| 2569 | p->tgid = current->tgid;
|
| 2570 | } else {
|
| 2571 | p->group_leader = p;
|
| 2572 | p->tgid = p->pid;
|
| 2573 | }
|
| 2574 |
|
| 2575 | p->nr_dirtied = 0;
|
| 2576 | p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
|
| 2577 | p->dirty_paused_when = 0;
|
| 2578 |
|
| 2579 | p->pdeath_signal = 0;
|
| 2580 | p->task_works = NULL;
|
| 2581 | clear_posix_cputimers_work(p);
|
| 2582 |
|
| 2583 | #ifdef CONFIG_KRETPROBES
|
| 2584 | p->kretprobe_instances.first = NULL;
|
| 2585 | #endif
|
| 2586 | #ifdef CONFIG_RETHOOK
|
| 2587 | p->rethooks.first = NULL;
|
| 2588 | #endif
|
| 2589 |
|
| 2590 | |
| 2591 | * Ensure that the cgroup subsystem policies allow the new process to be
|
| 2592 | * forked. It should be noted that the new process's css_set can be changed
|
| 2593 | * between here and cgroup_post_fork() if an organisation operation is in
|
| 2594 | * progress.
|
| 2595 |
|
| 2596 | retval = cgroup_can_fork(p, args);
|
| 2597 | if (retval)
|
| 2598 | goto bad_fork_put_pidfd;
|
| 2599 |
|
| 2600 | |
| 2601 | * Now that the cgroups are pinned, re-clone the parent cgroup and put
|
| 2602 | * the new task on the correct runqueue. All this *before* the task
|
| 2603 | * becomes visible.
|
| 2604 | *
|
| 2605 | * This isn't part of ->can_fork() because while the re-cloning is
|
| 2606 | * cgroup specific, it unconditionally needs to place the task on a
|
| 2607 | * runqueue.
|
| 2608 |
|
| 2609 | sched_cgroup_fork(p, args);
|
| 2610 |
|
| 2611 | |
| 2612 | * From this point on we must avoid any synchronous user-space
|
| 2613 | * communication until we take the tasklist-lock. In particular, we do
|
| 2614 | * not want user-space to be able to predict the process start-time by
|
| 2615 | * stalling fork(2) after we recorded the start_time but before it is
|
| 2616 | * visible to the system.
|
| 2617 |
|
| 2618 |
|
| 2619 | p->start_time = ktime_get_ns();
|
| 2620 | p->start_boottime = ktime_get_boottime_ns();
|
| 2621 |
|
| 2622 | |
| 2623 | * Make it visible to the rest of the system, but dont wake it up yet.
|
| 2624 | * Need tasklist lock for parent etc handling!
|
| 2625 |
|
| 2626 | write_lock_irq(&tasklist_lock);
|
| 2627 |
|
| 2628 |
|
| 2629 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
|
| 2630 | p->real_parent = current->real_parent;
|
| 2631 | p->parent_exec_id = current->parent_exec_id;
|
| 2632 | if (clone_flags & CLONE_THREAD)
|
| 2633 | p->exit_signal = -1;
|
| 2634 | else
|
| 2635 | p->exit_signal = current->group_leader->exit_signal;
|
| 2636 | } else {
|
| 2637 | p->real_parent = current;
|
| 2638 | p->parent_exec_id = current->self_exec_id;
|
| 2639 | p->exit_signal = args->exit_signal;
|
| 2640 | }
|
| 2641 |
|
| 2642 | klp_copy_process(p);
|
| 2643 |
|
| 2644 | sched_core_fork(p);
|
| 2645 |
|
| 2646 | spin_lock(¤t->sighand->siglock);
|
| 2647 |
|
| 2648 | rv_task_fork(p);
|
| 2649 |
|
| 2650 | rseq_fork(p, clone_flags);
|
| 2651 |
|
| 2652 |
|
| 2653 | if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
|
| 2654 | retval = -ENOMEM;
|
| 2655 | goto bad_fork_cancel_cgroup;
|
| 2656 | }
|
| 2657 |
|
| 2658 |
|
| 2659 | if (fatal_signal_pending(current)) {
|
| 2660 | retval = -EINTR;
|
| 2661 | goto bad_fork_cancel_cgroup;
|
| 2662 | }
|
| 2663 |
|
| 2664 |
|
| 2665 |
|
| 2666 | |
| 2667 | * Copy seccomp details explicitly here, in case they were changed
|
| 2668 | * before holding sighand lock.
|
| 2669 |
|
| 2670 | copy_seccomp(p);
|
| 2671 |
|
| 2672 | init_task_pid_links(p);
|
| 2673 | if (likely(p->pid)) {
|
| 2674 | ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
|
| 2675 |
|
| 2676 | init_task_pid(p, PIDTYPE_PID, pid);
|
| 2677 | if (thread_group_leader(p)) {
|
| 2678 | init_task_pid(p, PIDTYPE_TGID, pid);
|
| 2679 | init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
|
| 2680 | init_task_pid(p, PIDTYPE_SID, task_session(current));
|
| 2681 |
|
| 2682 | if (is_child_reaper(pid)) {
|
| 2683 | ns_of_pid(pid)->child_reaper = p;
|
| 2684 | p->signal->flags |= SIGNAL_UNKILLABLE;
|
| 2685 | }
|
| 2686 | p->signal->shared_pending.signal = delayed.signal;
|
| 2687 | p->signal->tty = tty_kref_get(current->signal->tty);
|
| 2688 | |
| 2689 | * Inherit has_child_subreaper flag under the same
|
| 2690 | * tasklist_lock with adding child to the process tree
|
| 2691 | * for propagate_has_child_subreaper optimization.
|
| 2692 |
|
| 2693 | p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
|
| 2694 | p->real_parent->signal->is_child_subreaper;
|
| 2695 | list_add_tail(&p->sibling, &p->real_parent->children);
|
| 2696 | list_add_tail_rcu(&p->tasks, &init_task.tasks);
|
| 2697 | attach_pid(p, PIDTYPE_TGID);
|
| 2698 | attach_pid(p, PIDTYPE_PGID);
|
| 2699 | attach_pid(p, PIDTYPE_SID);
|
| 2700 | __this_cpu_inc(process_counts);
|
| 2701 | } else {
|
| 2702 | current->signal->nr_threads++;
|
| 2703 | current->signal->quick_threads++;
|
| 2704 | atomic_inc(¤t->signal->live);
|
| 2705 | refcount_inc(¤t->signal->sigcnt);
|
| 2706 | task_join_group_stop(p);
|
| 2707 | list_add_tail_rcu(&p->thread_node,
|
| 2708 | &p->signal->thread_head);
|
| 2709 | }
|
| 2710 | attach_pid(p, PIDTYPE_PID);
|
| 2711 | nr_threads++;
|
| 2712 | }
|
| 2713 | total_forks++;
|
| 2714 | hlist_del_init(&delayed.node);
|
| 2715 | spin_unlock(¤t->sighand->siglock);
|
| 2716 | syscall_tracepoint_update(p);
|
| 2717 | write_unlock_irq(&tasklist_lock);
|
| 2718 |
|
| 2719 | if (pidfile)
|
| 2720 | fd_install(pidfd, pidfile);
|
| 2721 |
|
| 2722 | proc_fork_connector(p);
|
| 2723 | sched_post_fork(p);
|
| 2724 | cgroup_post_fork(p, args);
|
| 2725 | perf_event_fork(p);
|
| 2726 |
|
| 2727 | trace_task_newtask(p, clone_flags);
|
| 2728 | uprobe_copy_process(p, clone_flags);
|
| 2729 | user_events_fork(p, clone_flags);
|
| 2730 |
|
| 2731 | copy_oom_score_adj(clone_flags, p);
|
| 2732 |
|
| 2733 | return p;
|
| 2734 |
|
| 2735 | bad_fork_cancel_cgroup:
|
| 2736 | sched_core_free(p);
|
| 2737 | spin_unlock(¤t->sighand->siglock);
|
| 2738 | write_unlock_irq(&tasklist_lock);
|
| 2739 | cgroup_cancel_fork(p, args);
|
| 2740 | bad_fork_put_pidfd:
|
| 2741 | if (clone_flags & CLONE_PIDFD) {
|
| 2742 | fput(pidfile);
|
| 2743 | put_unused_fd(pidfd);
|
| 2744 | }
|
| 2745 | bad_fork_free_pid:
|
| 2746 | if (pid != &init_struct_pid)
|
| 2747 | free_pid(pid);
|
| 2748 | bad_fork_cleanup_thread:
|
| 2749 | exit_thread(p);
|
| 2750 | bad_fork_cleanup_io:
|
| 2751 | if (p->io_context)
|
| 2752 | exit_io_context(p);
|
| 2753 | bad_fork_cleanup_namespaces:
|
| 2754 | exit_task_namespaces(p);
|
| 2755 | bad_fork_cleanup_mm:
|
| 2756 | if (p->mm) {
|
| 2757 | mm_clear_owner(p->mm, p);
|
| 2758 | mmput(p->mm);
|
| 2759 | }
|
| 2760 | bad_fork_cleanup_signal:
|
| 2761 | if (!(clone_flags & CLONE_THREAD))
|
| 2762 | free_signal_struct(p->signal);
|
| 2763 | bad_fork_cleanup_sighand:
|
| 2764 | __cleanup_sighand(p->sighand);
|
| 2765 | bad_fork_cleanup_fs:
|
| 2766 | exit_fs(p);
|
| 2767 | bad_fork_cleanup_files:
|
| 2768 | exit_files(p);
|
| 2769 | bad_fork_cleanup_semundo:
|
| 2770 | exit_sem(p);
|
| 2771 | bad_fork_cleanup_security:
|
| 2772 | security_task_free(p);
|
| 2773 | bad_fork_cleanup_audit:
|
| 2774 | audit_free(p);
|
| 2775 | bad_fork_cleanup_perf:
|
| 2776 | perf_event_free_task(p);
|
| 2777 | bad_fork_cleanup_policy:
|
| 2778 | lockdep_free_task(p);
|
| 2779 | #ifdef CONFIG_NUMA
|
| 2780 | mpol_put(p->mempolicy);
|
| 2781 | #endif
|
| 2782 | bad_fork_cleanup_delayacct:
|
| 2783 | delayacct_tsk_free(p);
|
| 2784 | bad_fork_cleanup_count:
|
| 2785 | dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
|
| 2786 | exit_creds(p);
|
| 2787 | bad_fork_free:
|
| 2788 | WRITE_ONCE(p->__state, TASK_DEAD);
|
| 2789 | exit_task_stack_account(p);
|
| 2790 | put_task_stack(p);
|
| 2791 | delayed_free_task(p);
|
| 2792 | fork_out:
|
| 2793 | spin_lock_irq(¤t->sighand->siglock);
|
| 2794 | hlist_del_init(&delayed.node);
|
| 2795 | spin_unlock_irq(¤t->sighand->siglock);
|
| 2796 | return ERR_PTR(retval);
|
| 2797 | }
|
| 2798 |
|
| 2799 | static inline void init_idle_pids(struct task_struct *idle)
|
| 2800 | {
|
| 2801 | enum pid_type type;
|
| 2802 |
|
| 2803 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
|
| 2804 | INIT_HLIST_NODE(&idle->pid_links[type]);
|
| 2805 | init_task_pid(idle, type, &init_struct_pid);
|
| 2806 | }
|
| 2807 | }
|
| 2808 |
|
| 2809 | static int idle_dummy(void *dummy)
|
| 2810 | {
|
| 2811 |
|
| 2812 | return 0;
|
| 2813 | }
|
| 2814 |
|
| 2815 | struct task_struct * __init fork_idle(int cpu)
|
| 2816 | {
|
| 2817 | struct task_struct *task;
|
| 2818 | struct kernel_clone_args args = {
|
| 2819 | .flags = CLONE_VM,
|
| 2820 | .fn = &idle_dummy,
|
| 2821 | .fn_arg = NULL,
|
| 2822 | .kthread = 1,
|
| 2823 | .idle = 1,
|
| 2824 | };
|
| 2825 |
|
| 2826 | task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
|
| 2827 | if (!IS_ERR(task)) {
|
| 2828 | init_idle_pids(task);
|
| 2829 | init_idle(task, cpu);
|
| 2830 | }
|
| 2831 |
|
| 2832 | return task;
|
| 2833 | }
|
| 2834 |
|
| 2835 | |
| 2836 | * This is like kernel_clone(), but shaved down and tailored to just
|
| 2837 | * creating io_uring workers. It returns a created task, or an error pointer.
|
| 2838 | * The returned task is inactive, and the caller must fire it up through
|
| 2839 | * wake_up_new_task(p). All signals are blocked in the created task.
|
| 2840 |
|
| 2841 | struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
|
| 2842 | {
|
| 2843 | unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
|
| 2844 | CLONE_IO;
|
| 2845 | struct kernel_clone_args args = {
|
| 2846 | .flags = ((lower_32_bits(flags) | CLONE_VM |
|
| 2847 | CLONE_UNTRACED) & ~CSIGNAL),
|
| 2848 | .exit_signal = (lower_32_bits(flags) & CSIGNAL),
|
| 2849 | .fn = fn,
|
| 2850 | .fn_arg = arg,
|
| 2851 | .io_thread = 1,
|
| 2852 | .user_worker = 1,
|
| 2853 | };
|
| 2854 |
|
| 2855 | return copy_process(NULL, 0, node, &args);
|
| 2856 | }
|
| 2857 |
|
| 2858 | |
| 2859 | * Ok, this is the main fork-routine.
|
| 2860 | *
|
| 2861 | * It copies the process, and if successful kick-starts
|
| 2862 | * it and waits for it to finish using the VM if required.
|
| 2863 | *
|
| 2864 | * args->exit_signal is expected to be checked for sanity by the caller.
|
| 2865 |
|
| 2866 | pid_t kernel_clone(struct kernel_clone_args *args)
|
| 2867 | {
|
| 2868 | u64 clone_flags = args->flags;
|
| 2869 | struct completion vfork;
|
| 2870 | struct pid *pid;
|
| 2871 | struct task_struct *p;
|
| 2872 | int trace = 0;
|
| 2873 | pid_t nr;
|
| 2874 |
|
| 2875 | |
| 2876 | * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
|
| 2877 | * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
|
| 2878 | * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
|
| 2879 | * field in struct clone_args and it still doesn't make sense to have
|
| 2880 | * them both point at the same memory location. Performing this check
|
| 2881 | * here has the advantage that we don't need to have a separate helper
|
| 2882 | * to check for legacy clone().
|
| 2883 |
|
| 2884 | if ((args->flags & CLONE_PIDFD) &&
|
| 2885 | (args->flags & CLONE_PARENT_SETTID) &&
|
| 2886 | (args->pidfd == args->parent_tid))
|
| 2887 | return -EINVAL;
|
| 2888 |
|
| 2889 | |
| 2890 | * Determine whether and which event to report to ptracer. When
|
| 2891 | * called from kernel_thread or CLONE_UNTRACED is explicitly
|
| 2892 | * requested, no event is reported; otherwise, report if the event
|
| 2893 | * for the type of forking is enabled.
|
| 2894 |
|
| 2895 | if (!(clone_flags & CLONE_UNTRACED)) {
|
| 2896 | if (clone_flags & CLONE_VFORK)
|
| 2897 | trace = PTRACE_EVENT_VFORK;
|
| 2898 | else if (args->exit_signal != SIGCHLD)
|
| 2899 | trace = PTRACE_EVENT_CLONE;
|
| 2900 | else
|
| 2901 | trace = PTRACE_EVENT_FORK;
|
| 2902 |
|
| 2903 | if (likely(!ptrace_event_enabled(current, trace)))
|
| 2904 | trace = 0;
|
| 2905 | }
|
| 2906 |
|
| 2907 | p = copy_process(NULL, trace, NUMA_NO_NODE, args);
|
| 2908 | add_latent_entropy();
|
| 2909 |
|
| 2910 | if (IS_ERR(p))
|
| 2911 | return PTR_ERR(p);
|
| 2912 |
|
| 2913 | |
| 2914 | * Do this prior waking up the new thread - the thread pointer
|
| 2915 | * might get invalid after that point, if the thread exits quickly.
|
| 2916 |
|
| 2917 | trace_sched_process_fork(current, p);
|
| 2918 |
|
| 2919 | pid = get_task_pid(p, PIDTYPE_PID);
|
| 2920 | nr = pid_vnr(pid);
|
| 2921 |
|
| 2922 | if (clone_flags & CLONE_PARENT_SETTID)
|
| 2923 | put_user(nr, args->parent_tid);
|
| 2924 |
|
| 2925 | if (clone_flags & CLONE_VFORK) {
|
| 2926 | p->vfork_done = &vfork;
|
| 2927 | init_completion(&vfork);
|
| 2928 | get_task_struct(p);
|
| 2929 | }
|
| 2930 |
|
| 2931 | if (IS_ENABLED(CONFIG_LRU_GEN) && !(clone_flags & CLONE_VM)) {
|
| 2932 |
|
| 2933 | task_lock(p);
|
| 2934 | lru_gen_add_mm(p->mm);
|
| 2935 | task_unlock(p);
|
| 2936 | }
|
| 2937 |
|
| 2938 | wake_up_new_task(p);
|
| 2939 |
|
| 2940 |
|
| 2941 | if (unlikely(trace))
|
| 2942 | ptrace_event_pid(trace, pid);
|
| 2943 |
|
| 2944 | if (clone_flags & CLONE_VFORK) {
|
| 2945 | if (!wait_for_vfork_done(p, &vfork))
|
| 2946 | ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
|
| 2947 | }
|
| 2948 |
|
| 2949 | put_pid(pid);
|
| 2950 | return nr;
|
| 2951 | }
|
| 2952 |
|
| 2953 | |
| 2954 | * Create a kernel thread.
|
| 2955 |
|
| 2956 | pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
|
| 2957 | unsigned long flags)
|
| 2958 | {
|
| 2959 | struct kernel_clone_args args = {
|
| 2960 | .flags = ((lower_32_bits(flags) | CLONE_VM |
|
| 2961 | CLONE_UNTRACED) & ~CSIGNAL),
|
| 2962 | .exit_signal = (lower_32_bits(flags) & CSIGNAL),
|
| 2963 | .fn = fn,
|
| 2964 | .fn_arg = arg,
|
| 2965 | .name = name,
|
| 2966 | .kthread = 1,
|
| 2967 | };
|
| 2968 |
|
| 2969 | return kernel_clone(&args);
|
| 2970 | }
|
| 2971 |
|
| 2972 | |
| 2973 | * Create a user mode thread.
|
| 2974 |
|
| 2975 | pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
|
| 2976 | {
|
| 2977 | struct kernel_clone_args args = {
|
| 2978 | .flags = ((lower_32_bits(flags) | CLONE_VM |
|
| 2979 | CLONE_UNTRACED) & ~CSIGNAL),
|
| 2980 | .exit_signal = (lower_32_bits(flags) & CSIGNAL),
|
| 2981 | .fn = fn,
|
| 2982 | .fn_arg = arg,
|
| 2983 | };
|
| 2984 |
|
| 2985 | return kernel_clone(&args);
|
| 2986 | }
|
| 2987 |
|
| 2988 | #ifdef __ARCH_WANT_SYS_FORK
|
| 2989 | SYSCALL_DEFINE0(fork)
|
| 2990 | {
|
| 2991 | #ifdef CONFIG_MMU
|
| 2992 | struct kernel_clone_args args = {
|
| 2993 | .exit_signal = SIGCHLD,
|
| 2994 | };
|
| 2995 |
|
| 2996 | return kernel_clone(&args);
|
| 2997 | #else
|
| 2998 |
|
| 2999 | return -EINVAL;
|
| 3000 | #endif
|
| 3001 | }
|
| 3002 | #endif
|
| 3003 |
|
| 3004 | #ifdef __ARCH_WANT_SYS_VFORK
|
| 3005 | SYSCALL_DEFINE0(vfork)
|
| 3006 | {
|
| 3007 | struct kernel_clone_args args = {
|
| 3008 | .flags = CLONE_VFORK | CLONE_VM,
|
| 3009 | .exit_signal = SIGCHLD,
|
| 3010 | };
|
| 3011 |
|
| 3012 | return kernel_clone(&args);
|
| 3013 | }
|
| 3014 | #endif
|
| 3015 |
|
| 3016 | #ifdef __ARCH_WANT_SYS_CLONE
|
| 3017 | #ifdef CONFIG_CLONE_BACKWARDS
|
| 3018 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
|
| 3019 | int __user *, parent_tidptr,
|
| 3020 | unsigned long, tls,
|
| 3021 | int __user *, child_tidptr)
|
| 3022 | #elif defined(CONFIG_CLONE_BACKWARDS2)
|
| 3023 | SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
|
| 3024 | int __user *, parent_tidptr,
|
| 3025 | int __user *, child_tidptr,
|
| 3026 | unsigned long, tls)
|
| 3027 | #elif defined(CONFIG_CLONE_BACKWARDS3)
|
| 3028 | SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
|
| 3029 | int, stack_size,
|
| 3030 | int __user *, parent_tidptr,
|
| 3031 | int __user *, child_tidptr,
|
| 3032 | unsigned long, tls)
|
| 3033 | #else
|
| 3034 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
|
| 3035 | int __user *, parent_tidptr,
|
| 3036 | int __user *, child_tidptr,
|
| 3037 | unsigned long, tls)
|
| 3038 | #endif
|
| 3039 | {
|
| 3040 | struct kernel_clone_args args = {
|
| 3041 | .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
|
| 3042 | .pidfd = parent_tidptr,
|
| 3043 | .child_tid = child_tidptr,
|
| 3044 | .parent_tid = parent_tidptr,
|
| 3045 | .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
|
| 3046 | .stack = newsp,
|
| 3047 | .tls = tls,
|
| 3048 | };
|
| 3049 |
|
| 3050 | return kernel_clone(&args);
|
| 3051 | }
|
| 3052 | #endif
|
| 3053 |
|
| 3054 | #ifdef __ARCH_WANT_SYS_CLONE3
|
| 3055 |
|
| 3056 | noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
|
| 3057 | struct clone_args __user *uargs,
|
| 3058 | size_t usize)
|
| 3059 | {
|
| 3060 | int err;
|
| 3061 | struct clone_args args;
|
| 3062 | pid_t *kset_tid = kargs->set_tid;
|
| 3063 |
|
| 3064 | BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
|
| 3065 | CLONE_ARGS_SIZE_VER0);
|
| 3066 | BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
|
| 3067 | CLONE_ARGS_SIZE_VER1);
|
| 3068 | BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
|
| 3069 | CLONE_ARGS_SIZE_VER2);
|
| 3070 | BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
|
| 3071 |
|
| 3072 | if (unlikely(usize > PAGE_SIZE))
|
| 3073 | return -E2BIG;
|
| 3074 | if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
|
| 3075 | return -EINVAL;
|
| 3076 |
|
| 3077 | err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
|
| 3078 | if (err)
|
| 3079 | return err;
|
| 3080 |
|
| 3081 | if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
|
| 3082 | return -EINVAL;
|
| 3083 |
|
| 3084 | if (unlikely(!args.set_tid && args.set_tid_size > 0))
|
| 3085 | return -EINVAL;
|
| 3086 |
|
| 3087 | if (unlikely(args.set_tid && args.set_tid_size == 0))
|
| 3088 | return -EINVAL;
|
| 3089 |
|
| 3090 | |
| 3091 | * Verify that higher 32bits of exit_signal are unset and that
|
| 3092 | * it is a valid signal
|
| 3093 |
|
| 3094 | if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
|
| 3095 | !valid_signal(args.exit_signal)))
|
| 3096 | return -EINVAL;
|
| 3097 |
|
| 3098 | if ((args.flags & CLONE_INTO_CGROUP) &&
|
| 3099 | (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
|
| 3100 | return -EINVAL;
|
| 3101 |
|
| 3102 | *kargs = (struct kernel_clone_args){
|
| 3103 | .flags = args.flags,
|
| 3104 | .pidfd = u64_to_user_ptr(args.pidfd),
|
| 3105 | .child_tid = u64_to_user_ptr(args.child_tid),
|
| 3106 | .parent_tid = u64_to_user_ptr(args.parent_tid),
|
| 3107 | .exit_signal = args.exit_signal,
|
| 3108 | .stack = args.stack,
|
| 3109 | .stack_size = args.stack_size,
|
| 3110 | .tls = args.tls,
|
| 3111 | .set_tid_size = args.set_tid_size,
|
| 3112 | .cgroup = args.cgroup,
|
| 3113 | };
|
| 3114 |
|
| 3115 | if (args.set_tid &&
|
| 3116 | copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
|
| 3117 | (kargs->set_tid_size * sizeof(pid_t))))
|
| 3118 | return -EFAULT;
|
| 3119 |
|
| 3120 | kargs->set_tid = kset_tid;
|
| 3121 |
|
| 3122 | return 0;
|
| 3123 | }
|
| 3124 |
|
| 3125 | |
| 3126 | * clone3_stack_valid - check and prepare stack
|
| 3127 | * @kargs: kernel clone args
|
| 3128 | *
|
| 3129 | * Verify that the stack arguments userspace gave us are sane.
|
| 3130 | * In addition, set the stack direction for userspace since it's easy for us to
|
| 3131 | * determine.
|
| 3132 |
|
| 3133 | static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
|
| 3134 | {
|
| 3135 | if (kargs->stack == 0) {
|
| 3136 | if (kargs->stack_size > 0)
|
| 3137 | return false;
|
| 3138 | } else {
|
| 3139 | if (kargs->stack_size == 0)
|
| 3140 | return false;
|
| 3141 |
|
| 3142 | if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
|
| 3143 | return false;
|
| 3144 |
|
| 3145 | #if !defined(CONFIG_STACK_GROWSUP)
|
| 3146 | kargs->stack += kargs->stack_size;
|
| 3147 | #endif
|
| 3148 | }
|
| 3149 |
|
| 3150 | return true;
|
| 3151 | }
|
| 3152 |
|
| 3153 | static bool clone3_args_valid(struct kernel_clone_args *kargs)
|
| 3154 | {
|
| 3155 |
|
| 3156 | if (kargs->flags &
|
| 3157 | ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
|
| 3158 | return false;
|
| 3159 |
|
| 3160 | |
| 3161 | * - make the CLONE_DETACHED bit reusable for clone3
|
| 3162 | * - make the CSIGNAL bits reusable for clone3
|
| 3163 |
|
| 3164 | if (kargs->flags & (CLONE_DETACHED | (CSIGNAL & (~CLONE_NEWTIME))))
|
| 3165 | return false;
|
| 3166 |
|
| 3167 | if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
|
| 3168 | (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
|
| 3169 | return false;
|
| 3170 |
|
| 3171 | if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
|
| 3172 | kargs->exit_signal)
|
| 3173 | return false;
|
| 3174 |
|
| 3175 | if (!clone3_stack_valid(kargs))
|
| 3176 | return false;
|
| 3177 |
|
| 3178 | return true;
|
| 3179 | }
|
| 3180 |
|
| 3181 | |
| 3182 | * sys_clone3 - create a new process with specific properties
|
| 3183 | * @uargs: argument structure
|
| 3184 | * @size: size of @uargs
|
| 3185 | *
|
| 3186 | * clone3() is the extensible successor to clone()/clone2().
|
| 3187 | * It takes a struct as argument that is versioned by its size.
|
| 3188 | *
|
| 3189 | * Return: On success, a positive PID for the child process.
|
| 3190 | * On error, a negative errno number.
|
| 3191 |
|
| 3192 | SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
|
| 3193 | {
|
| 3194 | int err;
|
| 3195 |
|
| 3196 | struct kernel_clone_args kargs;
|
| 3197 | pid_t set_tid[MAX_PID_NS_LEVEL];
|
| 3198 |
|
| 3199 | kargs.set_tid = set_tid;
|
| 3200 |
|
| 3201 | err = copy_clone_args_from_user(&kargs, uargs, size);
|
| 3202 | if (err)
|
| 3203 | return err;
|
| 3204 |
|
| 3205 | if (!clone3_args_valid(&kargs))
|
| 3206 | return -EINVAL;
|
| 3207 |
|
| 3208 | return kernel_clone(&kargs);
|
| 3209 | }
|
| 3210 | #endif
|
| 3211 |
|
| 3212 | void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
|
| 3213 | {
|
| 3214 | struct task_struct *leader, *parent, *child;
|
| 3215 | int res;
|
| 3216 |
|
| 3217 | read_lock(&tasklist_lock);
|
| 3218 | leader = top = top->group_leader;
|
| 3219 | down:
|
| 3220 | for_each_thread(leader, parent) {
|
| 3221 | list_for_each_entry(child, &parent->children, sibling) {
|
| 3222 | res = visitor(child, data);
|
| 3223 | if (res) {
|
| 3224 | if (res < 0)
|
| 3225 | goto out;
|
| 3226 | leader = child;
|
| 3227 | goto down;
|
| 3228 | }
|
| 3229 | up:
|
| 3230 | ;
|
| 3231 | }
|
| 3232 | }
|
| 3233 |
|
| 3234 | if (leader != top) {
|
| 3235 | child = leader;
|
| 3236 | parent = child->real_parent;
|
| 3237 | leader = parent->group_leader;
|
| 3238 | goto up;
|
| 3239 | }
|
| 3240 | out:
|
| 3241 | read_unlock(&tasklist_lock);
|
| 3242 | }
|
| 3243 |
|
| 3244 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN
|
| 3245 | #define ARCH_MIN_MMSTRUCT_ALIGN 0
|
| 3246 | #endif
|
| 3247 |
|
| 3248 | static void sighand_ctor(void *data)
|
| 3249 | {
|
| 3250 | struct sighand_struct *sighand = data;
|
| 3251 |
|
| 3252 | spin_lock_init(&sighand->siglock);
|
| 3253 | init_waitqueue_head(&sighand->signalfd_wqh);
|
| 3254 | }
|
| 3255 |
|
| 3256 | void __init mm_cache_init(void)
|
| 3257 | {
|
| 3258 | unsigned int mm_size;
|
| 3259 |
|
| 3260 | |
| 3261 | * The mm_cpumask is located at the end of mm_struct, and is
|
| 3262 | * dynamically sized based on the maximum CPU number this system
|
| 3263 | * can have, taking hotplug into account (nr_cpu_ids).
|
| 3264 |
|
| 3265 | mm_size = sizeof(struct mm_struct) + cpumask_size() + mm_cid_size();
|
| 3266 |
|
| 3267 | mm_cachep = kmem_cache_create_usercopy("mm_struct",
|
| 3268 | mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
|
| 3269 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
| 3270 | offsetof(struct mm_struct, saved_auxv),
|
| 3271 | sizeof_field(struct mm_struct, saved_auxv),
|
| 3272 | NULL);
|
| 3273 | }
|
| 3274 |
|
| 3275 | void __init proc_caches_init(void)
|
| 3276 | {
|
| 3277 | sighand_cachep = kmem_cache_create("sighand_cache",
|
| 3278 | sizeof(struct sighand_struct), 0,
|
| 3279 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
|
| 3280 | SLAB_ACCOUNT, sighand_ctor);
|
| 3281 | signal_cachep = kmem_cache_create("signal_cache",
|
| 3282 | sizeof(struct signal_struct), 0,
|
| 3283 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
| 3284 | NULL);
|
| 3285 | files_cachep = kmem_cache_create("files_cache",
|
| 3286 | sizeof(struct files_struct), 0,
|
| 3287 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
| 3288 | NULL);
|
| 3289 | fs_cachep = kmem_cache_create("fs_cache",
|
| 3290 | sizeof(struct fs_struct), 0,
|
| 3291 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
| 3292 | NULL);
|
| 3293 |
|
| 3294 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
|
| 3295 | #ifdef CONFIG_PER_VMA_LOCK
|
| 3296 | vma_lock_cachep = KMEM_CACHE(vma_lock, SLAB_PANIC|SLAB_ACCOUNT);
|
| 3297 | #endif
|
| 3298 | mmap_init();
|
| 3299 | nsproxy_cache_init();
|
| 3300 | }
|
| 3301 |
|
| 3302 | |
| 3303 | * Check constraints on flags passed to the unshare system call.
|
| 3304 |
|
| 3305 | static int check_unshare_flags(unsigned long unshare_flags)
|
| 3306 | {
|
| 3307 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
|
| 3308 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
|
| 3309 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
|
| 3310 | CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
|
| 3311 | CLONE_NEWTIME))
|
| 3312 | return -EINVAL;
|
| 3313 | |
| 3314 | * Not implemented, but pretend it works if there is nothing
|
| 3315 | * to unshare. Note that unsharing the address space or the
|
| 3316 | * signal handlers also need to unshare the signal queues (aka
|
| 3317 | * CLONE_THREAD).
|
| 3318 |
|
| 3319 | if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
|
| 3320 | if (!thread_group_empty(current))
|
| 3321 | return -EINVAL;
|
| 3322 | }
|
| 3323 | if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
|
| 3324 | if (refcount_read(¤t->sighand->count) > 1)
|
| 3325 | return -EINVAL;
|
| 3326 | }
|
| 3327 | if (unshare_flags & CLONE_VM) {
|
| 3328 | if (!current_is_single_threaded())
|
| 3329 | return -EINVAL;
|
| 3330 | }
|
| 3331 |
|
| 3332 | return 0;
|
| 3333 | }
|
| 3334 |
|
| 3335 | |
| 3336 | * Unshare the filesystem structure if it is being shared
|
| 3337 |
|
| 3338 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
|
| 3339 | {
|
| 3340 | struct fs_struct *fs = current->fs;
|
| 3341 |
|
| 3342 | if (!(unshare_flags & CLONE_FS) || !fs)
|
| 3343 | return 0;
|
| 3344 |
|
| 3345 |
|
| 3346 | if (fs->users == 1)
|
| 3347 | return 0;
|
| 3348 |
|
| 3349 | *new_fsp = copy_fs_struct(fs);
|
| 3350 | if (!*new_fsp)
|
| 3351 | return -ENOMEM;
|
| 3352 |
|
| 3353 | return 0;
|
| 3354 | }
|
| 3355 |
|
| 3356 | |
| 3357 | * Unshare file descriptor table if it is being shared
|
| 3358 |
|
| 3359 | int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
|
| 3360 | struct files_struct **new_fdp)
|
| 3361 | {
|
| 3362 | struct files_struct *fd = current->files;
|
| 3363 | int error = 0;
|
| 3364 |
|
| 3365 | if ((unshare_flags & CLONE_FILES) &&
|
| 3366 | (fd && atomic_read(&fd->count) > 1)) {
|
| 3367 | *new_fdp = dup_fd(fd, max_fds, &error);
|
| 3368 | if (!*new_fdp)
|
| 3369 | return error;
|
| 3370 | }
|
| 3371 |
|
| 3372 | return 0;
|
| 3373 | }
|
| 3374 |
|
| 3375 | |
| 3376 | * unshare allows a process to 'unshare' part of the process
|
| 3377 | * context which was originally shared using clone. copy_*
|
| 3378 | * functions used by kernel_clone() cannot be used here directly
|
| 3379 | * because they modify an inactive task_struct that is being
|
| 3380 | * constructed. Here we are modifying the current, active,
|
| 3381 | * task_struct.
|
| 3382 |
|
| 3383 | int ksys_unshare(unsigned long unshare_flags)
|
| 3384 | {
|
| 3385 | struct fs_struct *fs, *new_fs = NULL;
|
| 3386 | struct files_struct *new_fd = NULL;
|
| 3387 | struct cred *new_cred = NULL;
|
| 3388 | struct nsproxy *new_nsproxy = NULL;
|
| 3389 | int do_sysvsem = 0;
|
| 3390 | int err;
|
| 3391 |
|
| 3392 | |
| 3393 | * If unsharing a user namespace must also unshare the thread group
|
| 3394 | * and unshare the filesystem root and working directories.
|
| 3395 |
|
| 3396 | if (unshare_flags & CLONE_NEWUSER)
|
| 3397 | unshare_flags |= CLONE_THREAD | CLONE_FS;
|
| 3398 | |
| 3399 | * If unsharing vm, must also unshare signal handlers.
|
| 3400 |
|
| 3401 | if (unshare_flags & CLONE_VM)
|
| 3402 | unshare_flags |= CLONE_SIGHAND;
|
| 3403 | |
| 3404 | * If unsharing a signal handlers, must also unshare the signal queues.
|
| 3405 |
|
| 3406 | if (unshare_flags & CLONE_SIGHAND)
|
| 3407 | unshare_flags |= CLONE_THREAD;
|
| 3408 | |
| 3409 | * If unsharing namespace, must also unshare filesystem information.
|
| 3410 |
|
| 3411 | if (unshare_flags & CLONE_NEWNS)
|
| 3412 | unshare_flags |= CLONE_FS;
|
| 3413 |
|
| 3414 | err = check_unshare_flags(unshare_flags);
|
| 3415 | if (err)
|
| 3416 | goto bad_unshare_out;
|
| 3417 | |
| 3418 | * CLONE_NEWIPC must also detach from the undolist: after switching
|
| 3419 | * to a new ipc namespace, the semaphore arrays from the old
|
| 3420 | * namespace are unreachable.
|
| 3421 |
|
| 3422 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
|
| 3423 | do_sysvsem = 1;
|
| 3424 | err = unshare_fs(unshare_flags, &new_fs);
|
| 3425 | if (err)
|
| 3426 | goto bad_unshare_out;
|
| 3427 | err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
|
| 3428 | if (err)
|
| 3429 | goto bad_unshare_cleanup_fs;
|
| 3430 | err = unshare_userns(unshare_flags, &new_cred);
|
| 3431 | if (err)
|
| 3432 | goto bad_unshare_cleanup_fd;
|
| 3433 | err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
|
| 3434 | new_cred, new_fs);
|
| 3435 | if (err)
|
| 3436 | goto bad_unshare_cleanup_cred;
|
| 3437 |
|
| 3438 | if (new_cred) {
|
| 3439 | err = set_cred_ucounts(new_cred);
|
| 3440 | if (err)
|
| 3441 | goto bad_unshare_cleanup_cred;
|
| 3442 | }
|
| 3443 |
|
| 3444 | if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
|
| 3445 | if (do_sysvsem) {
|
| 3446 | |
| 3447 | * CLONE_SYSVSEM is equivalent to sys_exit().
|
| 3448 |
|
| 3449 | exit_sem(current);
|
| 3450 | }
|
| 3451 | if (unshare_flags & CLONE_NEWIPC) {
|
| 3452 |
|
| 3453 | exit_shm(current);
|
| 3454 | shm_init_task(current);
|
| 3455 | }
|
| 3456 |
|
| 3457 | if (new_nsproxy)
|
| 3458 | switch_task_namespaces(current, new_nsproxy);
|
| 3459 |
|
| 3460 | task_lock(current);
|
| 3461 |
|
| 3462 | if (new_fs) {
|
| 3463 | fs = current->fs;
|
| 3464 | spin_lock(&fs->lock);
|
| 3465 | current->fs = new_fs;
|
| 3466 | if (--fs->users)
|
| 3467 | new_fs = NULL;
|
| 3468 | else
|
| 3469 | new_fs = fs;
|
| 3470 | spin_unlock(&fs->lock);
|
| 3471 | }
|
| 3472 |
|
| 3473 | if (new_fd)
|
| 3474 | swap(current->files, new_fd);
|
| 3475 |
|
| 3476 | task_unlock(current);
|
| 3477 |
|
| 3478 | if (new_cred) {
|
| 3479 |
|
| 3480 | commit_creds(new_cred);
|
| 3481 | new_cred = NULL;
|
| 3482 | }
|
| 3483 | }
|
| 3484 |
|
| 3485 | perf_event_namespaces(current);
|
| 3486 |
|
| 3487 | bad_unshare_cleanup_cred:
|
| 3488 | if (new_cred)
|
| 3489 | put_cred(new_cred);
|
| 3490 | bad_unshare_cleanup_fd:
|
| 3491 | if (new_fd)
|
| 3492 | put_files_struct(new_fd);
|
| 3493 |
|
| 3494 | bad_unshare_cleanup_fs:
|
| 3495 | if (new_fs)
|
| 3496 | free_fs_struct(new_fs);
|
| 3497 |
|
| 3498 | bad_unshare_out:
|
| 3499 | return err;
|
| 3500 | }
|
| 3501 |
|
| 3502 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
|
| 3503 | {
|
| 3504 | return ksys_unshare(unshare_flags);
|
| 3505 | }
|
| 3506 |
|
| 3507 | |
| 3508 | * Helper to unshare the files of the current task.
|
| 3509 | * We don't want to expose copy_files internals to
|
| 3510 | * the exec layer of the kernel.
|
| 3511 |
|
| 3512 |
|
| 3513 | int unshare_files(void)
|
| 3514 | {
|
| 3515 | struct task_struct *task = current;
|
| 3516 | struct files_struct *old, *copy = NULL;
|
| 3517 | int error;
|
| 3518 |
|
| 3519 | error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
|
| 3520 | if (error || !copy)
|
| 3521 | return error;
|
| 3522 |
|
| 3523 | old = task->files;
|
| 3524 | task_lock(task);
|
| 3525 | task->files = copy;
|
| 3526 | task_unlock(task);
|
| 3527 | put_files_struct(old);
|
| 3528 | return 0;
|
| 3529 | }
|
| 3530 |
|
| 3531 | int sysctl_max_threads(struct ctl_table *table, int write,
|
| 3532 | void *buffer, size_t *lenp, loff_t *ppos)
|
| 3533 | {
|
| 3534 | struct ctl_table t;
|
| 3535 | int ret;
|
| 3536 | int threads = max_threads;
|
| 3537 | int min = 1;
|
| 3538 | int max = MAX_THREADS;
|
| 3539 |
|
| 3540 | t = *table;
|
| 3541 | t.data = &threads;
|
| 3542 | t.extra1 = &min;
|
| 3543 | t.extra2 = &max;
|
| 3544 |
|
| 3545 | ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
|
| 3546 | if (ret || !write)
|
| 3547 | return ret;
|
| 3548 |
|
| 3549 | max_threads = threads;
|
| 3550 |
|
| 3551 | return 0;
|
| 3552 | }
|