| 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/user.h>
|
| 20 | #include <linux/sched/numa_balancing.h>
|
| 21 | #include <linux/sched/stat.h>
|
| 22 | #include <linux/sched/task.h>
|
| 23 | #include <linux/sched/task_stack.h>
|
| 24 | #include <linux/sched/cputime.h>
|
| 25 | #include <linux/sched/ext.h>
|
| 26 | #include <linux/sched/exec_state.h>
|
| 27 | #include <linux/seq_file.h>
|
| 28 | #include <linux/rtmutex.h>
|
| 29 | #include <linux/init.h>
|
| 30 | #include <linux/unistd.h>
|
| 31 | #include <linux/module.h>
|
| 32 | #include <linux/vmalloc.h>
|
| 33 | #include <linux/completion.h>
|
| 34 | #include <linux/personality.h>
|
| 35 | #include <linux/mempolicy.h>
|
| 36 | #include <linux/sem.h>
|
| 37 | #include <linux/file.h>
|
| 38 | #include <linux/fdtable.h>
|
| 39 | #include <linux/iocontext.h>
|
| 40 | #include <linux/key.h>
|
| 41 | #include <linux/kmsan.h>
|
| 42 | #include <linux/binfmts.h>
|
| 43 | #include <linux/mman.h>
|
| 44 | #include <linux/mmu_notifier.h>
|
| 45 | #include <linux/fs.h>
|
| 46 | #include <linux/mm.h>
|
| 47 | #include <linux/mm_inline.h>
|
| 48 | #include <linux/memblock.h>
|
| 49 | #include <linux/nsproxy.h>
|
| 50 | #include <linux/ns/ns_common_types.h>
|
| 51 | #include <linux/capability.h>
|
| 52 | #include <linux/cpu.h>
|
| 53 | #include <linux/cgroup.h>
|
| 54 | #include <linux/security.h>
|
| 55 | #include <linux/hugetlb.h>
|
| 56 | #include <linux/seccomp.h>
|
| 57 | #include <linux/swap.h>
|
| 58 | #include <linux/syscalls.h>
|
| 59 | #include <linux/syscall_user_dispatch.h>
|
| 60 | #include <linux/jiffies.h>
|
| 61 | #include <linux/futex.h>
|
| 62 | #include <linux/compat.h>
|
| 63 | #include <linux/kthread.h>
|
| 64 | #include <linux/task_io_accounting_ops.h>
|
| 65 | #include <linux/rcupdate.h>
|
| 66 | #include <linux/ptrace.h>
|
| 67 | #include <linux/mount.h>
|
| 68 | #include <linux/audit.h>
|
| 69 | #include <linux/memcontrol.h>
|
| 70 | #include <linux/ftrace.h>
|
| 71 | #include <linux/proc_fs.h>
|
| 72 | #include <linux/profile.h>
|
| 73 | #include <linux/rmap.h>
|
| 74 | #include <linux/ksm.h>
|
| 75 | #include <linux/acct.h>
|
| 76 | #include <linux/userfaultfd_k.h>
|
| 77 | #include <linux/tsacct_kern.h>
|
| 78 | #include <linux/cn_proc.h>
|
| 79 | #include <linux/freezer.h>
|
| 80 | #include <linux/delayacct.h>
|
| 81 | #include <linux/taskstats_kern.h>
|
| 82 | #include <linux/tty.h>
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| 83 | #include <linux/fs_struct.h>
|
| 84 | #include <linux/magic.h>
|
| 85 | #include <linux/perf_event.h>
|
| 86 | #include <linux/posix-timers.h>
|
| 87 | #include <linux/user-return-notifier.h>
|
| 88 | #include <linux/oom.h>
|
| 89 | #include <linux/khugepaged.h>
|
| 90 | #include <linux/signalfd.h>
|
| 91 | #include <linux/uprobes.h>
|
| 92 | #include <linux/aio.h>
|
| 93 | #include <linux/compiler.h>
|
| 94 | #include <linux/sysctl.h>
|
| 95 | #include <linux/kcov.h>
|
| 96 | #include <linux/livepatch.h>
|
| 97 | #include <linux/thread_info.h>
|
| 98 | #include <linux/kstack_erase.h>
|
| 99 | #include <linux/kasan.h>
|
| 100 | #include <linux/randomize_kstack.h>
|
| 101 | #include <linux/scs.h>
|
| 102 | #include <linux/io_uring.h>
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| 103 | #include <linux/io_uring_types.h>
|
| 104 | #include <linux/bpf.h>
|
| 105 | #include <linux/stackprotector.h>
|
| 106 | #include <linux/user_events.h>
|
| 107 | #include <linux/iommu.h>
|
| 108 | #include <linux/rseq.h>
|
| 109 | #include <uapi/linux/pidfd.h>
|
| 110 | #include <linux/pidfs.h>
|
| 111 | #include <linux/tick.h>
|
| 112 | #include <linux/unwind_deferred.h>
|
| 113 | #include <linux/pgalloc.h>
|
| 114 | #include <linux/uaccess.h>
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| 115 |
|
| 116 | #include <asm/mmu_context.h>
|
| 117 | #include <asm/cacheflush.h>
|
| 118 | #include <asm/tlbflush.h>
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| 119 |
|
| 120 |
|
| 121 | #include "../mm/internal.h"
|
| 122 |
|
| 123 | #include <trace/events/sched.h>
|
| 124 |
|
| 125 | #define CREATE_TRACE_POINTS
|
| 126 | #include <trace/events/task.h>
|
| 127 |
|
| 128 | #include <kunit/visibility.h>
|
| 129 |
|
| 130 | |
| 131 | * Minimum number of threads to boot the kernel
|
| 132 |
|
| 133 | #define MIN_THREADS 20
|
| 134 |
|
| 135 | |
| 136 | * Maximum number of threads
|
| 137 |
|
| 138 | #define MAX_THREADS FUTEX_TID_MASK
|
| 139 |
|
| 140 | |
| 141 | * Protected counters by write_lock_irq(&tasklist_lock)
|
| 142 |
|
| 143 | unsigned long total_forks;
|
| 144 | int nr_threads;
|
| 145 |
|
| 146 | static int max_threads;
|
| 147 |
|
| 148 | #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
|
| 149 |
|
| 150 | static const char * const resident_page_types[] = {
|
| 151 | NAMED_ARRAY_INDEX(MM_FILEPAGES),
|
| 152 | NAMED_ARRAY_INDEX(MM_ANONPAGES),
|
| 153 | NAMED_ARRAY_INDEX(MM_SWAPENTS),
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| 154 | NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
|
| 155 | };
|
| 156 |
|
| 157 | DEFINE_PER_CPU(unsigned long, process_counts) = 0;
|
| 158 |
|
| 159 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock);
|
| 160 |
|
| 161 | #ifdef CONFIG_PROVE_RCU
|
| 162 | int lockdep_tasklist_lock_is_held(void)
|
| 163 | {
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| 164 | return lockdep_is_held(&tasklist_lock);
|
| 165 | }
|
| 166 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
|
| 167 | #endif
|
| 168 |
|
| 169 | int nr_processes(void)
|
| 170 | {
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| 171 | int cpu;
|
| 172 | int total = 0;
|
| 173 |
|
| 174 | for_each_possible_cpu(cpu)
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| 175 | total += per_cpu(process_counts, cpu);
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| 176 |
|
| 177 | return total;
|
| 178 | }
|
| 179 |
|
| 180 | void __weak arch_release_task_struct(struct task_struct *tsk)
|
| 181 | {
|
| 182 | }
|
| 183 |
|
| 184 | static struct kmem_cache *task_struct_cachep;
|
| 185 |
|
| 186 | static inline struct task_struct *alloc_task_struct_node(int node)
|
| 187 | {
|
| 188 | return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
|
| 189 | }
|
| 190 |
|
| 191 | static inline void free_task_struct(struct task_struct *tsk)
|
| 192 | {
|
| 193 | kmem_cache_free(task_struct_cachep, tsk);
|
| 194 | }
|
| 195 |
|
| 196 | #ifdef CONFIG_VMAP_STACK
|
| 197 | |
| 198 | * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
|
| 199 | * flush. Try to minimize the number of calls by caching stacks.
|
| 200 |
|
| 201 | #define NR_CACHED_STACKS 2
|
| 202 | static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
|
| 203 | |
| 204 | * Allocated stacks are cached and later reused by new threads, so memcg
|
| 205 | * accounting is performed by the code assigning/releasing stacks to tasks.
|
| 206 | * We need a zeroed memory without __GFP_ACCOUNT.
|
| 207 |
|
| 208 | #define GFP_VMAP_STACK (GFP_KERNEL | __GFP_ZERO | __GFP_SKIP_KASAN)
|
| 209 |
|
| 210 | struct vm_stack {
|
| 211 | struct rcu_head rcu;
|
| 212 | struct vm_struct *stack_vm_area;
|
| 213 | };
|
| 214 |
|
| 215 | static struct vm_struct *alloc_thread_stack_node_from_cache(struct task_struct *tsk, int node)
|
| 216 | {
|
| 217 | struct vm_struct *vm_area;
|
| 218 | unsigned int i;
|
| 219 |
|
| 220 | |
| 221 | * If the node has memory, we are guaranteed the stacks are backed by local pages.
|
| 222 | * Otherwise the pages are arbitrary.
|
| 223 | *
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| 224 | * Note that depending on cpuset it is possible we will get migrated to a different
|
| 225 | * node immediately after allocating here, so this does *not* guarantee locality for
|
| 226 | * arbitrary callers.
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| 227 |
|
| 228 | scoped_guard(preempt) {
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| 229 | if (node != NUMA_NO_NODE && numa_node_id() != node)
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| 230 | return NULL;
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| 231 |
|
| 232 | for (i = 0; i < NR_CACHED_STACKS; i++) {
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| 233 | vm_area = this_cpu_xchg(cached_stacks[i], NULL);
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| 234 | if (vm_area)
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| 235 | return vm_area;
|
| 236 | }
|
| 237 | }
|
| 238 |
|
| 239 | return NULL;
|
| 240 | }
|
| 241 |
|
| 242 | static bool try_release_thread_stack_to_cache(struct vm_struct *vm_area)
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| 243 | {
|
| 244 | unsigned int i;
|
| 245 | int nid;
|
| 246 |
|
| 247 | |
| 248 | * Don't cache stacks if any of the pages don't match the local domain, unless
|
| 249 | * there is no local memory to begin with.
|
| 250 | *
|
| 251 | * Note that lack of local memory does not automatically mean it makes no difference
|
| 252 | * performance-wise which other domain backs the stack. In this case we are merely
|
| 253 | * trying to avoid constantly going to vmalloc.
|
| 254 |
|
| 255 | scoped_guard(preempt) {
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| 256 | nid = numa_node_id();
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| 257 | if (node_state(nid, N_MEMORY)) {
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| 258 | for (i = 0; i < vm_area->nr_pages; i++) {
|
| 259 | struct page *page = vm_area->pages[i];
|
| 260 | if (page_to_nid(page) != nid)
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| 261 | return false;
|
| 262 | }
|
| 263 | }
|
| 264 |
|
| 265 | for (i = 0; i < NR_CACHED_STACKS; i++) {
|
| 266 | struct vm_struct *tmp = NULL;
|
| 267 |
|
| 268 | if (this_cpu_try_cmpxchg(cached_stacks[i], &tmp, vm_area))
|
| 269 | return true;
|
| 270 | }
|
| 271 | }
|
| 272 | return false;
|
| 273 | }
|
| 274 |
|
| 275 | static void thread_stack_free_rcu(struct rcu_head *rh)
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| 276 | {
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| 277 | struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
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| 278 | struct vm_struct *vm_area = vm_stack->stack_vm_area;
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| 279 |
|
| 280 | if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
|
| 281 | return;
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| 282 |
|
| 283 | vfree(vm_area->addr);
|
| 284 | }
|
| 285 |
|
| 286 | static void thread_stack_delayed_free(struct task_struct *tsk)
|
| 287 | {
|
| 288 | struct vm_stack *vm_stack = tsk->stack;
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| 289 |
|
| 290 | vm_stack->stack_vm_area = tsk->stack_vm_area;
|
| 291 | call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
|
| 292 | }
|
| 293 |
|
| 294 | static int free_vm_stack_cache(unsigned int cpu)
|
| 295 | {
|
| 296 | struct vm_struct **cached_vm_stack_areas = per_cpu_ptr(cached_stacks, cpu);
|
| 297 | int i;
|
| 298 |
|
| 299 | for (i = 0; i < NR_CACHED_STACKS; i++) {
|
| 300 | struct vm_struct *vm_area = cached_vm_stack_areas[i];
|
| 301 |
|
| 302 | if (!vm_area)
|
| 303 | continue;
|
| 304 |
|
| 305 | vfree(vm_area->addr);
|
| 306 | cached_vm_stack_areas[i] = NULL;
|
| 307 | }
|
| 308 |
|
| 309 | return 0;
|
| 310 | }
|
| 311 |
|
| 312 | static int memcg_charge_kernel_stack(struct vm_struct *vm_area)
|
| 313 | {
|
| 314 | int i;
|
| 315 | int ret;
|
| 316 | int nr_charged = 0;
|
| 317 |
|
| 318 | BUG_ON(vm_area->nr_pages != THREAD_SIZE / PAGE_SIZE);
|
| 319 |
|
| 320 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
|
| 321 | ret = memcg_kmem_charge_page(vm_area->pages[i], GFP_KERNEL, 0);
|
| 322 | if (ret)
|
| 323 | goto err;
|
| 324 | nr_charged++;
|
| 325 | }
|
| 326 | return 0;
|
| 327 | err:
|
| 328 | for (i = 0; i < nr_charged; i++)
|
| 329 | memcg_kmem_uncharge_page(vm_area->pages[i], 0);
|
| 330 | return ret;
|
| 331 | }
|
| 332 |
|
| 333 | static int alloc_thread_stack_node(struct task_struct *tsk, int node)
|
| 334 | {
|
| 335 | struct vm_struct *vm_area;
|
| 336 | void *stack;
|
| 337 |
|
| 338 | vm_area = alloc_thread_stack_node_from_cache(tsk, node);
|
| 339 | if (vm_area) {
|
| 340 | if (memcg_charge_kernel_stack(vm_area)) {
|
| 341 | vfree(vm_area->addr);
|
| 342 | return -ENOMEM;
|
| 343 | }
|
| 344 |
|
| 345 |
|
| 346 | if (!kasan_hw_tags_enabled())
|
| 347 | kasan_unpoison_range(vm_area->addr, THREAD_SIZE);
|
| 348 |
|
| 349 | stack = kasan_reset_tag(vm_area->addr);
|
| 350 |
|
| 351 |
|
| 352 | clear_pages(vm_area->addr, vm_area->nr_pages);
|
| 353 |
|
| 354 | tsk->stack_vm_area = vm_area;
|
| 355 | tsk->stack = stack;
|
| 356 | return 0;
|
| 357 | }
|
| 358 |
|
| 359 | stack = __vmalloc_node(THREAD_SIZE, THREAD_ALIGN,
|
| 360 | GFP_VMAP_STACK,
|
| 361 | node, __builtin_return_address(0));
|
| 362 | if (!stack)
|
| 363 | return -ENOMEM;
|
| 364 |
|
| 365 | vm_area = find_vm_area(stack);
|
| 366 | if (memcg_charge_kernel_stack(vm_area)) {
|
| 367 | vfree(stack);
|
| 368 | return -ENOMEM;
|
| 369 | }
|
| 370 | |
| 371 | * We can't call find_vm_area() in interrupt context, and
|
| 372 | * free_thread_stack() can be called in interrupt context,
|
| 373 | * so cache the vm_struct.
|
| 374 |
|
| 375 | tsk->stack_vm_area = vm_area;
|
| 376 | stack = kasan_reset_tag(stack);
|
| 377 | tsk->stack = stack;
|
| 378 | return 0;
|
| 379 | }
|
| 380 |
|
| 381 | static void free_thread_stack(struct task_struct *tsk)
|
| 382 | {
|
| 383 | if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
|
| 384 | thread_stack_delayed_free(tsk);
|
| 385 |
|
| 386 | tsk->stack = NULL;
|
| 387 | tsk->stack_vm_area = NULL;
|
| 388 | }
|
| 389 |
|
| 390 | #else
|
| 391 |
|
| 392 | |
| 393 | * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
|
| 394 | * kmemcache based allocator.
|
| 395 |
|
| 396 | #if THREAD_SIZE >= PAGE_SIZE
|
| 397 |
|
| 398 | static void thread_stack_free_rcu(struct rcu_head *rh)
|
| 399 | {
|
| 400 | __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
|
| 401 | }
|
| 402 |
|
| 403 | static void thread_stack_delayed_free(struct task_struct *tsk)
|
| 404 | {
|
| 405 | struct rcu_head *rh = tsk->stack;
|
| 406 |
|
| 407 | call_rcu(rh, thread_stack_free_rcu);
|
| 408 | }
|
| 409 |
|
| 410 | static int alloc_thread_stack_node(struct task_struct *tsk, int node)
|
| 411 | {
|
| 412 | struct page *page = alloc_pages_node(node, THREADINFO_GFP,
|
| 413 | THREAD_SIZE_ORDER);
|
| 414 |
|
| 415 | if (likely(page)) {
|
| 416 | tsk->stack = kasan_reset_tag(page_address(page));
|
| 417 | return 0;
|
| 418 | }
|
| 419 | return -ENOMEM;
|
| 420 | }
|
| 421 |
|
| 422 | static void free_thread_stack(struct task_struct *tsk)
|
| 423 | {
|
| 424 | thread_stack_delayed_free(tsk);
|
| 425 | tsk->stack = NULL;
|
| 426 | }
|
| 427 |
|
| 428 | #else
|
| 429 |
|
| 430 | static struct kmem_cache *thread_stack_cache;
|
| 431 |
|
| 432 | static void thread_stack_free_rcu(struct rcu_head *rh)
|
| 433 | {
|
| 434 | kmem_cache_free(thread_stack_cache, rh);
|
| 435 | }
|
| 436 |
|
| 437 | static void thread_stack_delayed_free(struct task_struct *tsk)
|
| 438 | {
|
| 439 | struct rcu_head *rh = tsk->stack;
|
| 440 |
|
| 441 | call_rcu(rh, thread_stack_free_rcu);
|
| 442 | }
|
| 443 |
|
| 444 | static int alloc_thread_stack_node(struct task_struct *tsk, int node)
|
| 445 | {
|
| 446 | unsigned long *stack;
|
| 447 | stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
|
| 448 | stack = kasan_reset_tag(stack);
|
| 449 | tsk->stack = stack;
|
| 450 | return stack ? 0 : -ENOMEM;
|
| 451 | }
|
| 452 |
|
| 453 | static void free_thread_stack(struct task_struct *tsk)
|
| 454 | {
|
| 455 | thread_stack_delayed_free(tsk);
|
| 456 | tsk->stack = NULL;
|
| 457 | }
|
| 458 |
|
| 459 | void thread_stack_cache_init(void)
|
| 460 | {
|
| 461 | thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
|
| 462 | THREAD_SIZE, THREAD_SIZE, 0, 0,
|
| 463 | THREAD_SIZE, NULL);
|
| 464 | BUG_ON(thread_stack_cache == NULL);
|
| 465 | }
|
| 466 |
|
| 467 | #endif
|
| 468 | #endif
|
| 469 |
|
| 470 |
|
| 471 | static struct kmem_cache *signal_cachep;
|
| 472 |
|
| 473 |
|
| 474 | struct kmem_cache *sighand_cachep;
|
| 475 |
|
| 476 |
|
| 477 | struct kmem_cache *files_cachep;
|
| 478 |
|
| 479 |
|
| 480 | struct kmem_cache *fs_cachep;
|
| 481 |
|
| 482 |
|
| 483 | static struct kmem_cache *mm_cachep;
|
| 484 |
|
| 485 | static void account_kernel_stack(struct task_struct *tsk, int account)
|
| 486 | {
|
| 487 | if (IS_ENABLED(CONFIG_VMAP_STACK)) {
|
| 488 | struct vm_struct *vm_area = task_stack_vm_area(tsk);
|
| 489 | int i;
|
| 490 |
|
| 491 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
|
| 492 | mod_lruvec_page_state(vm_area->pages[i], NR_KERNEL_STACK_KB,
|
| 493 | account * (PAGE_SIZE / 1024));
|
| 494 | } else {
|
| 495 | void *stack = task_stack_page(tsk);
|
| 496 |
|
| 497 |
|
| 498 | mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
|
| 499 | account * (THREAD_SIZE / 1024));
|
| 500 | }
|
| 501 | }
|
| 502 |
|
| 503 | void exit_task_stack_account(struct task_struct *tsk)
|
| 504 | {
|
| 505 | account_kernel_stack(tsk, -1);
|
| 506 |
|
| 507 | if (IS_ENABLED(CONFIG_VMAP_STACK)) {
|
| 508 | struct vm_struct *vm_area;
|
| 509 | int i;
|
| 510 |
|
| 511 | vm_area = task_stack_vm_area(tsk);
|
| 512 | for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
|
| 513 | memcg_kmem_uncharge_page(vm_area->pages[i], 0);
|
| 514 | }
|
| 515 | }
|
| 516 |
|
| 517 | static void release_task_stack(struct task_struct *tsk)
|
| 518 | {
|
| 519 | if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
|
| 520 | return;
|
| 521 |
|
| 522 | free_thread_stack(tsk);
|
| 523 | }
|
| 524 |
|
| 525 | #ifdef CONFIG_THREAD_INFO_IN_TASK
|
| 526 | void put_task_stack(struct task_struct *tsk)
|
| 527 | {
|
| 528 | if (refcount_dec_and_test(&tsk->stack_refcount))
|
| 529 | release_task_stack(tsk);
|
| 530 | }
|
| 531 | #endif
|
| 532 |
|
| 533 | void free_task(struct task_struct *tsk)
|
| 534 | {
|
| 535 | #ifdef CONFIG_SECCOMP
|
| 536 | WARN_ON_ONCE(tsk->seccomp.filter);
|
| 537 | #endif
|
| 538 | release_user_cpus_ptr(tsk);
|
| 539 | scs_release(tsk);
|
| 540 |
|
| 541 | #ifndef CONFIG_THREAD_INFO_IN_TASK
|
| 542 | |
| 543 | * The task is finally done with both the stack and thread_info,
|
| 544 | * so free both.
|
| 545 |
|
| 546 | release_task_stack(tsk);
|
| 547 | #else
|
| 548 | |
| 549 | * If the task had a separate stack allocation, it should be gone
|
| 550 | * by now.
|
| 551 |
|
| 552 | WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
|
| 553 | #endif
|
| 554 | rt_mutex_debug_task_free(tsk);
|
| 555 | ftrace_graph_exit_task(tsk);
|
| 556 | arch_release_task_struct(tsk);
|
| 557 | if (tsk->flags & PF_KTHREAD)
|
| 558 | free_kthread_struct(tsk);
|
| 559 | bpf_task_storage_free(tsk);
|
| 560 | put_task_exec_state(rcu_access_pointer(tsk->exec_state));
|
| 561 | free_task_struct(tsk);
|
| 562 | }
|
| 563 | EXPORT_SYMBOL(free_task);
|
| 564 |
|
| 565 | void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
|
| 566 | {
|
| 567 | struct file *exe_file;
|
| 568 |
|
| 569 | exe_file = get_mm_exe_file(oldmm);
|
| 570 | RCU_INIT_POINTER(mm->exe_file, exe_file);
|
| 571 | |
| 572 | * We depend on the oldmm having properly denied write access to the
|
| 573 | * exe_file already.
|
| 574 |
|
| 575 | if (exe_file && exe_file_deny_write_access(exe_file))
|
| 576 | pr_warn_once("exe_file_deny_write_access() failed in %s\n", __func__);
|
| 577 | }
|
| 578 |
|
| 579 | #ifdef CONFIG_MMU
|
| 580 | static inline int mm_alloc_pgd(struct mm_struct *mm)
|
| 581 | {
|
| 582 | mm->pgd = pgd_alloc(mm);
|
| 583 | if (unlikely(!mm->pgd))
|
| 584 | return -ENOMEM;
|
| 585 | return 0;
|
| 586 | }
|
| 587 |
|
| 588 | static inline void mm_free_pgd(struct mm_struct *mm)
|
| 589 | {
|
| 590 | pgd_free(mm, mm->pgd);
|
| 591 | }
|
| 592 | #else
|
| 593 | #define mm_alloc_pgd(mm) (0)
|
| 594 | #define mm_free_pgd(mm)
|
| 595 | #endif
|
| 596 |
|
| 597 | #ifdef CONFIG_MM_ID
|
| 598 | static DEFINE_IDA(mm_ida);
|
| 599 |
|
| 600 | static inline int mm_alloc_id(struct mm_struct *mm)
|
| 601 | {
|
| 602 | int ret;
|
| 603 |
|
| 604 | ret = ida_alloc_range(&mm_ida, MM_ID_MIN, MM_ID_MAX, GFP_KERNEL);
|
| 605 | if (ret < 0)
|
| 606 | return ret;
|
| 607 | mm->mm_id = ret;
|
| 608 | return 0;
|
| 609 | }
|
| 610 |
|
| 611 | static inline void mm_free_id(struct mm_struct *mm)
|
| 612 | {
|
| 613 | const mm_id_t id = mm->mm_id;
|
| 614 |
|
| 615 | mm->mm_id = MM_ID_DUMMY;
|
| 616 | if (id == MM_ID_DUMMY)
|
| 617 | return;
|
| 618 | if (WARN_ON_ONCE(id < MM_ID_MIN || id > MM_ID_MAX))
|
| 619 | return;
|
| 620 | ida_free(&mm_ida, id);
|
| 621 | }
|
| 622 | #else
|
| 623 | static inline int mm_alloc_id(struct mm_struct *mm) { return 0; }
|
| 624 | static inline void mm_free_id(struct mm_struct *mm) {}
|
| 625 | #endif
|
| 626 |
|
| 627 | static void check_mm(struct mm_struct *mm)
|
| 628 | {
|
| 629 | int i;
|
| 630 |
|
| 631 | BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
|
| 632 | "Please make sure 'struct resident_page_types[]' is updated as well");
|
| 633 |
|
| 634 | for (i = 0; i < NR_MM_COUNTERS; i++) {
|
| 635 | long x = percpu_counter_sum(&mm->rss_stat[i]);
|
| 636 |
|
| 637 | if (unlikely(x)) {
|
| 638 | pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld Comm:%s Pid:%d\n",
|
| 639 | mm, resident_page_types[i], x,
|
| 640 | current->comm,
|
| 641 | task_pid_nr(current));
|
| 642 | }
|
| 643 | }
|
| 644 |
|
| 645 | if (mm_pgtables_bytes(mm))
|
| 646 | pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
|
| 647 | mm_pgtables_bytes(mm));
|
| 648 |
|
| 649 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !defined(CONFIG_SPLIT_PMD_PTLOCKS)
|
| 650 | VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
|
| 651 | #endif
|
| 652 | }
|
| 653 |
|
| 654 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
|
| 655 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
|
| 656 |
|
| 657 | static void do_check_lazy_tlb(void *arg)
|
| 658 | {
|
| 659 | struct mm_struct *mm = arg;
|
| 660 |
|
| 661 | WARN_ON_ONCE(current->active_mm == mm);
|
| 662 | }
|
| 663 |
|
| 664 | static void do_shoot_lazy_tlb(void *arg)
|
| 665 | {
|
| 666 | struct mm_struct *mm = arg;
|
| 667 |
|
| 668 | if (current->active_mm == mm) {
|
| 669 | WARN_ON_ONCE(current->mm);
|
| 670 | current->active_mm = &init_mm;
|
| 671 | switch_mm(mm, &init_mm, current);
|
| 672 | }
|
| 673 | }
|
| 674 |
|
| 675 | static void cleanup_lazy_tlbs(struct mm_struct *mm)
|
| 676 | {
|
| 677 | if (!IS_ENABLED(CONFIG_MMU_LAZY_TLB_SHOOTDOWN)) {
|
| 678 | |
| 679 | * In this case, lazy tlb mms are refounted and would not reach
|
| 680 | * __mmdrop until all CPUs have switched away and mmdrop()ed.
|
| 681 |
|
| 682 | return;
|
| 683 | }
|
| 684 |
|
| 685 | |
| 686 | * Lazy mm shootdown does not refcount "lazy tlb mm" usage, rather it
|
| 687 | * requires lazy mm users to switch to another mm when the refcount
|
| 688 | * drops to zero, before the mm is freed. This requires IPIs here to
|
| 689 | * switch kernel threads to init_mm.
|
| 690 | *
|
| 691 | * archs that use IPIs to flush TLBs can piggy-back that lazy tlb mm
|
| 692 | * switch with the final userspace teardown TLB flush which leaves the
|
| 693 | * mm lazy on this CPU but no others, reducing the need for additional
|
| 694 | * IPIs here. There are cases where a final IPI is still required here,
|
| 695 | * such as the final mmdrop being performed on a different CPU than the
|
| 696 | * one exiting, or kernel threads using the mm when userspace exits.
|
| 697 | *
|
| 698 | * IPI overheads have not found to be expensive, but they could be
|
| 699 | * reduced in a number of possible ways, for example (roughly
|
| 700 | * increasing order of complexity):
|
| 701 | * - The last lazy reference created by exit_mm() could instead switch
|
| 702 | * to init_mm, however it's probable this will run on the same CPU
|
| 703 | * immediately afterwards, so this may not reduce IPIs much.
|
| 704 | * - A batch of mms requiring IPIs could be gathered and freed at once.
|
| 705 | * - CPUs store active_mm where it can be remotely checked without a
|
| 706 | * lock, to filter out false-positives in the cpumask.
|
| 707 | * - After mm_users or mm_count reaches zero, switching away from the
|
| 708 | * mm could clear mm_cpumask to reduce some IPIs, perhaps together
|
| 709 | * with some batching or delaying of the final IPIs.
|
| 710 | * - A delayed freeing and RCU-like quiescing sequence based on mm
|
| 711 | * switching to avoid IPIs completely.
|
| 712 |
|
| 713 | on_each_cpu_mask(mm_cpumask(mm), do_shoot_lazy_tlb, (void *)mm, 1);
|
| 714 | if (IS_ENABLED(CONFIG_DEBUG_VM_SHOOT_LAZIES))
|
| 715 | on_each_cpu(do_check_lazy_tlb, (void *)mm, 1);
|
| 716 | }
|
| 717 |
|
| 718 | |
| 719 | * Called when the last reference to the mm
|
| 720 | * is dropped: either by a lazy thread or by
|
| 721 | * mmput. Free the page directory and the mm.
|
| 722 |
|
| 723 | void __mmdrop(struct mm_struct *mm)
|
| 724 | {
|
| 725 | BUG_ON(mm == &init_mm);
|
| 726 | WARN_ON_ONCE(mm == current->mm);
|
| 727 |
|
| 728 |
|
| 729 | cleanup_lazy_tlbs(mm);
|
| 730 |
|
| 731 | WARN_ON_ONCE(mm == current->active_mm);
|
| 732 | mm_destroy_sched(mm);
|
| 733 | mm_free_pgd(mm);
|
| 734 | mm_free_id(mm);
|
| 735 | destroy_context(mm);
|
| 736 | mmu_notifier_subscriptions_destroy(mm);
|
| 737 | check_mm(mm);
|
| 738 | mm_pasid_drop(mm);
|
| 739 | mm_destroy_cid(mm);
|
| 740 | percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS);
|
| 741 |
|
| 742 | free_mm(mm);
|
| 743 | }
|
| 744 | EXPORT_SYMBOL_GPL(__mmdrop);
|
| 745 |
|
| 746 | static void mmdrop_async_fn(struct work_struct *work)
|
| 747 | {
|
| 748 | struct mm_struct *mm;
|
| 749 |
|
| 750 | mm = container_of(work, struct mm_struct, async_put_work);
|
| 751 | __mmdrop(mm);
|
| 752 | }
|
| 753 |
|
| 754 | static void mmdrop_async(struct mm_struct *mm)
|
| 755 | {
|
| 756 | if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
|
| 757 | INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
|
| 758 | schedule_work(&mm->async_put_work);
|
| 759 | }
|
| 760 | }
|
| 761 |
|
| 762 | static inline void free_signal_struct(struct signal_struct *sig)
|
| 763 | {
|
| 764 | taskstats_tgid_free(sig);
|
| 765 | sched_autogroup_exit(sig);
|
| 766 | |
| 767 | * __mmdrop is not safe to call from softirq context on x86 due to
|
| 768 | * pgd_dtor so postpone it to the async context
|
| 769 |
|
| 770 | if (sig->oom_mm)
|
| 771 | mmdrop_async(sig->oom_mm);
|
| 772 | kmem_cache_free(signal_cachep, sig);
|
| 773 | }
|
| 774 |
|
| 775 | static inline void put_signal_struct(struct signal_struct *sig)
|
| 776 | {
|
| 777 | if (refcount_dec_and_test(&sig->sigcnt))
|
| 778 | free_signal_struct(sig);
|
| 779 | }
|
| 780 |
|
| 781 | void __put_task_struct(struct task_struct *tsk)
|
| 782 | {
|
| 783 | WARN_ON(!tsk->exit_state);
|
| 784 | WARN_ON(refcount_read(&tsk->usage));
|
| 785 | WARN_ON(tsk == current);
|
| 786 |
|
| 787 | unwind_task_free(tsk);
|
| 788 | io_uring_free(tsk);
|
| 789 | cgroup_task_free(tsk);
|
| 790 | task_numa_free(tsk, true);
|
| 791 | security_task_free(tsk);
|
| 792 | exit_creds(tsk);
|
| 793 | delayacct_tsk_free(tsk);
|
| 794 | put_signal_struct(tsk->signal);
|
| 795 | sched_core_free(tsk);
|
| 796 | free_task(tsk);
|
| 797 | }
|
| 798 | EXPORT_SYMBOL_GPL(__put_task_struct);
|
| 799 |
|
| 800 | void __put_task_struct_rcu_cb(struct rcu_head *rhp)
|
| 801 | {
|
| 802 | struct task_struct *task = container_of(rhp, struct task_struct, rcu);
|
| 803 |
|
| 804 | __put_task_struct(task);
|
| 805 | }
|
| 806 | EXPORT_SYMBOL_GPL(__put_task_struct_rcu_cb);
|
| 807 |
|
| 808 | void __init __weak arch_task_cache_init(void) { }
|
| 809 |
|
| 810 | |
| 811 | * set_max_threads
|
| 812 |
|
| 813 | static void __init set_max_threads(unsigned int max_threads_suggested)
|
| 814 | {
|
| 815 | u64 threads;
|
| 816 | unsigned long nr_pages = memblock_estimated_nr_free_pages();
|
| 817 |
|
| 818 | |
| 819 | * The number of threads shall be limited such that the thread
|
| 820 | * structures may only consume a small part of the available memory.
|
| 821 |
|
| 822 | if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
|
| 823 | threads = MAX_THREADS;
|
| 824 | else
|
| 825 | threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
|
| 826 | (u64) THREAD_SIZE * 8UL);
|
| 827 |
|
| 828 | if (threads > max_threads_suggested)
|
| 829 | threads = max_threads_suggested;
|
| 830 |
|
| 831 | max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
|
| 832 | }
|
| 833 |
|
| 834 | #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
|
| 835 |
|
| 836 | int arch_task_struct_size __read_mostly;
|
| 837 | #endif
|
| 838 |
|
| 839 | static void __init task_struct_whitelist(unsigned long *offset, unsigned long *size)
|
| 840 | {
|
| 841 |
|
| 842 | arch_thread_struct_whitelist(offset, size);
|
| 843 |
|
| 844 | |
| 845 | * Handle zero-sized whitelist or empty thread_struct, otherwise
|
| 846 | * adjust offset to position of thread_struct in task_struct.
|
| 847 |
|
| 848 | if (unlikely(*size == 0))
|
| 849 | *offset = 0;
|
| 850 | else
|
| 851 | *offset += offsetof(struct task_struct, thread);
|
| 852 | }
|
| 853 |
|
| 854 | void __init fork_init(void)
|
| 855 | {
|
| 856 | int i;
|
| 857 | #ifndef ARCH_MIN_TASKALIGN
|
| 858 | #define ARCH_MIN_TASKALIGN 0
|
| 859 | #endif
|
| 860 | int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
|
| 861 | unsigned long useroffset, usersize;
|
| 862 |
|
| 863 |
|
| 864 | task_struct_whitelist(&useroffset, &usersize);
|
| 865 | task_struct_cachep = kmem_cache_create_usercopy("task_struct",
|
| 866 | arch_task_struct_size, align,
|
| 867 | SLAB_PANIC|SLAB_ACCOUNT,
|
| 868 | useroffset, usersize, NULL);
|
| 869 |
|
| 870 |
|
| 871 | arch_task_cache_init();
|
| 872 |
|
| 873 | set_max_threads(MAX_THREADS);
|
| 874 |
|
| 875 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
|
| 876 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
|
| 877 | init_task.signal->rlim[RLIMIT_SIGPENDING] =
|
| 878 | init_task.signal->rlim[RLIMIT_NPROC];
|
| 879 |
|
| 880 | for (i = 0; i < UCOUNT_COUNTS; i++)
|
| 881 | init_user_ns.ucount_max[i] = max_threads/2;
|
| 882 |
|
| 883 | set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
|
| 884 | set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
|
| 885 | set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
|
| 886 | set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
|
| 887 |
|
| 888 | #ifdef CONFIG_VMAP_STACK
|
| 889 | cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
|
| 890 | NULL, free_vm_stack_cache);
|
| 891 | #endif
|
| 892 |
|
| 893 | scs_init();
|
| 894 |
|
| 895 | lockdep_init_task(&init_task);
|
| 896 | uprobes_init();
|
| 897 | }
|
| 898 |
|
| 899 | int __weak arch_dup_task_struct(struct task_struct *dst,
|
| 900 | struct task_struct *src)
|
| 901 | {
|
| 902 | *dst = *src;
|
| 903 | return 0;
|
| 904 | }
|
| 905 |
|
| 906 | void set_task_stack_end_magic(struct task_struct *tsk)
|
| 907 | {
|
| 908 | unsigned long *stackend;
|
| 909 |
|
| 910 | stackend = end_of_stack(tsk);
|
| 911 | *stackend = STACK_END_MAGIC;
|
| 912 | }
|
| 913 |
|
| 914 | static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
|
| 915 | {
|
| 916 | struct task_struct *tsk;
|
| 917 | int err;
|
| 918 |
|
| 919 | if (node == NUMA_NO_NODE)
|
| 920 | node = tsk_fork_get_node(orig);
|
| 921 | tsk = alloc_task_struct_node(node);
|
| 922 | if (!tsk)
|
| 923 | return NULL;
|
| 924 |
|
| 925 | err = arch_dup_task_struct(tsk, orig);
|
| 926 | if (err)
|
| 927 | goto free_tsk;
|
| 928 |
|
| 929 | err = alloc_thread_stack_node(tsk, node);
|
| 930 | if (err)
|
| 931 | goto free_tsk;
|
| 932 |
|
| 933 | #ifdef CONFIG_THREAD_INFO_IN_TASK
|
| 934 | refcount_set(&tsk->stack_refcount, 1);
|
| 935 | #endif
|
| 936 | account_kernel_stack(tsk, 1);
|
| 937 |
|
| 938 | err = scs_prepare(tsk, node);
|
| 939 | if (err)
|
| 940 | goto free_stack;
|
| 941 |
|
| 942 | #ifdef CONFIG_SECCOMP
|
| 943 | |
| 944 | * We must handle setting up seccomp filters once we're under
|
| 945 | * the sighand lock in case orig has changed between now and
|
| 946 | * then. Until then, filter must be NULL to avoid messing up
|
| 947 | * the usage counts on the error path calling free_task.
|
| 948 |
|
| 949 | tsk->seccomp.filter = NULL;
|
| 950 | #endif
|
| 951 |
|
| 952 | RCU_INIT_POINTER(tsk->exec_state, NULL);
|
| 953 |
|
| 954 | setup_thread_stack(tsk, orig);
|
| 955 | clear_user_return_notifier(tsk);
|
| 956 | clear_tsk_need_resched(tsk);
|
| 957 | set_task_stack_end_magic(tsk);
|
| 958 | clear_syscall_work_syscall_user_dispatch(tsk);
|
| 959 |
|
| 960 | #ifdef CONFIG_STACKPROTECTOR
|
| 961 | tsk->stack_canary = get_random_canary();
|
| 962 | #endif
|
| 963 | if (orig->cpus_ptr == &orig->cpus_mask)
|
| 964 | tsk->cpus_ptr = &tsk->cpus_mask;
|
| 965 | dup_user_cpus_ptr(tsk, orig, node);
|
| 966 |
|
| 967 | |
| 968 | * One for the user space visible state that goes away when reaped.
|
| 969 | * One for the scheduler.
|
| 970 |
|
| 971 | refcount_set(&tsk->rcu_users, 2);
|
| 972 |
|
| 973 | refcount_set(&tsk->usage, 1);
|
| 974 | #ifdef CONFIG_BLK_DEV_IO_TRACE
|
| 975 | tsk->btrace_seq = 0;
|
| 976 | #endif
|
| 977 | tsk->splice_pipe = NULL;
|
| 978 | tsk->task_frag.page = NULL;
|
| 979 | tsk->wake_q.next = NULL;
|
| 980 | tsk->worker_private = NULL;
|
| 981 |
|
| 982 | kcov_task_init(tsk);
|
| 983 | kmsan_task_create(tsk);
|
| 984 | kmap_local_fork(tsk);
|
| 985 |
|
| 986 | #ifdef CONFIG_FAULT_INJECTION
|
| 987 | tsk->fail_nth = 0;
|
| 988 | #endif
|
| 989 |
|
| 990 | #ifdef CONFIG_BLK_CGROUP
|
| 991 | tsk->throttle_disk = NULL;
|
| 992 | tsk->use_memdelay = 0;
|
| 993 | #endif
|
| 994 |
|
| 995 | #ifdef CONFIG_ARCH_HAS_CPU_PASID
|
| 996 | tsk->pasid_activated = 0;
|
| 997 | #endif
|
| 998 |
|
| 999 | #ifdef CONFIG_MEMCG
|
| 1000 | tsk->active_memcg = NULL;
|
| 1001 | #endif
|
| 1002 |
|
| 1003 | #ifdef CONFIG_X86_BUS_LOCK_DETECT
|
| 1004 | tsk->reported_split_lock = 0;
|
| 1005 | #endif
|
| 1006 |
|
| 1007 | #ifdef CONFIG_SCHED_MM_CID
|
| 1008 | tsk->mm_cid.cid = MM_CID_UNSET;
|
| 1009 | tsk->mm_cid.active = 0;
|
| 1010 | INIT_HLIST_NODE(&tsk->mm_cid.node);
|
| 1011 | #endif
|
| 1012 |
|
| 1013 | #ifdef CONFIG_BPF_SYSCALL
|
| 1014 | RCU_INIT_POINTER(tsk->bpf_storage, NULL);
|
| 1015 | tsk->bpf_ctx = NULL;
|
| 1016 | #endif
|
| 1017 | return tsk;
|
| 1018 |
|
| 1019 | free_stack:
|
| 1020 | exit_task_stack_account(tsk);
|
| 1021 | free_thread_stack(tsk);
|
| 1022 | free_tsk:
|
| 1023 | free_task_struct(tsk);
|
| 1024 | return NULL;
|
| 1025 | }
|
| 1026 |
|
| 1027 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
|
| 1028 |
|
| 1029 | static unsigned long coredump_filter = MMF_DUMP_FILTER_DEFAULT;
|
| 1030 |
|
| 1031 | static int __init coredump_filter_setup(char *s)
|
| 1032 | {
|
| 1033 | if (kstrtoul(s, 0, &coredump_filter))
|
| 1034 | return 0;
|
| 1035 | coredump_filter <<= MMF_DUMP_FILTER_SHIFT;
|
| 1036 | coredump_filter &= MMF_DUMP_FILTER_MASK;
|
| 1037 | return 1;
|
| 1038 | }
|
| 1039 |
|
| 1040 | __setup("coredump_filter=", coredump_filter_setup);
|
| 1041 |
|
| 1042 | #include <linux/init_task.h>
|
| 1043 |
|
| 1044 | static void mm_init_aio(struct mm_struct *mm)
|
| 1045 | {
|
| 1046 | #ifdef CONFIG_AIO
|
| 1047 | spin_lock_init(&mm->ioctx_lock);
|
| 1048 | mm->ioctx_table = NULL;
|
| 1049 | #endif
|
| 1050 | }
|
| 1051 |
|
| 1052 | static __always_inline void mm_clear_owner(struct mm_struct *mm,
|
| 1053 | struct task_struct *p)
|
| 1054 | {
|
| 1055 | #ifdef CONFIG_MEMCG
|
| 1056 | if (mm->owner == p)
|
| 1057 | WRITE_ONCE(mm->owner, NULL);
|
| 1058 | #endif
|
| 1059 | }
|
| 1060 |
|
| 1061 | static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
|
| 1062 | {
|
| 1063 | #ifdef CONFIG_MEMCG
|
| 1064 | mm->owner = p;
|
| 1065 | #endif
|
| 1066 | }
|
| 1067 |
|
| 1068 | static void mm_init_uprobes_state(struct mm_struct *mm)
|
| 1069 | {
|
| 1070 | #ifdef CONFIG_UPROBES
|
| 1071 | mm->uprobes_state.xol_area = NULL;
|
| 1072 | arch_uprobe_init_state(mm);
|
| 1073 | #endif
|
| 1074 | }
|
| 1075 |
|
| 1076 | static void mmap_init_lock(struct mm_struct *mm)
|
| 1077 | {
|
| 1078 | init_rwsem(&mm->mmap_lock);
|
| 1079 | mm_lock_seqcount_init(mm);
|
| 1080 | #ifdef CONFIG_PER_VMA_LOCK
|
| 1081 | rcuwait_init(&mm->vma_writer_wait);
|
| 1082 | #endif
|
| 1083 | }
|
| 1084 |
|
| 1085 | static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
|
| 1086 | {
|
| 1087 | mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
|
| 1088 | mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
|
| 1089 | atomic_set(&mm->mm_users, 1);
|
| 1090 | atomic_set(&mm->mm_count, 1);
|
| 1091 | seqcount_init(&mm->write_protect_seq);
|
| 1092 | mmap_init_lock(mm);
|
| 1093 | INIT_LIST_HEAD(&mm->mmlist);
|
| 1094 | mm_pgtables_bytes_init(mm);
|
| 1095 | mm->map_count = 0;
|
| 1096 | mm->locked_vm = 0;
|
| 1097 | atomic64_set(&mm->pinned_vm, 0);
|
| 1098 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
|
| 1099 | spin_lock_init(&mm->page_table_lock);
|
| 1100 | spin_lock_init(&mm->arg_lock);
|
| 1101 | mm_init_cpumask(mm);
|
| 1102 | mm_init_aio(mm);
|
| 1103 | mm_init_owner(mm, p);
|
| 1104 | mm_pasid_init(mm);
|
| 1105 | RCU_INIT_POINTER(mm->exe_file, NULL);
|
| 1106 | mmu_notifier_subscriptions_init(mm);
|
| 1107 | init_tlb_flush_pending(mm);
|
| 1108 | #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !defined(CONFIG_SPLIT_PMD_PTLOCKS)
|
| 1109 | mm->pmd_huge_pte = NULL;
|
| 1110 | #endif
|
| 1111 | mm_init_uprobes_state(mm);
|
| 1112 | hugetlb_count_init(mm);
|
| 1113 | futex_mm_init(mm);
|
| 1114 |
|
| 1115 | mm_flags_clear_all(mm);
|
| 1116 | if (current->mm) {
|
| 1117 | unsigned long flags = __mm_flags_get_word(current->mm);
|
| 1118 |
|
| 1119 | __mm_flags_overwrite_word(mm, mmf_init_legacy_flags(flags));
|
| 1120 | mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
|
| 1121 | } else {
|
| 1122 | __mm_flags_overwrite_word(mm, coredump_filter);
|
| 1123 | mm->def_flags = 0;
|
| 1124 | }
|
| 1125 |
|
| 1126 | if (mm_alloc_pgd(mm))
|
| 1127 | goto fail_mm_init;
|
| 1128 |
|
| 1129 | if (mm_alloc_id(mm))
|
| 1130 | goto fail_noid;
|
| 1131 |
|
| 1132 | if (init_new_context(p, mm))
|
| 1133 | goto fail_nocontext;
|
| 1134 |
|
| 1135 | if (mm_alloc_cid(mm, p))
|
| 1136 | goto fail_cid;
|
| 1137 |
|
| 1138 | if (mm_alloc_sched(mm))
|
| 1139 | goto fail_sched;
|
| 1140 |
|
| 1141 | if (percpu_counter_init_many(mm->rss_stat, 0, GFP_KERNEL_ACCOUNT,
|
| 1142 | NR_MM_COUNTERS))
|
| 1143 | goto fail_pcpu;
|
| 1144 |
|
| 1145 | lru_gen_init_mm(mm);
|
| 1146 | return mm;
|
| 1147 |
|
| 1148 | fail_pcpu:
|
| 1149 | mm_destroy_sched(mm);
|
| 1150 | fail_sched:
|
| 1151 | mm_destroy_cid(mm);
|
| 1152 | fail_cid:
|
| 1153 | destroy_context(mm);
|
| 1154 | fail_nocontext:
|
| 1155 | mm_free_id(mm);
|
| 1156 | fail_noid:
|
| 1157 | mm_free_pgd(mm);
|
| 1158 | fail_mm_init:
|
| 1159 | free_mm(mm);
|
| 1160 | return NULL;
|
| 1161 | }
|
| 1162 |
|
| 1163 | |
| 1164 | * Allocate and initialize an mm_struct.
|
| 1165 |
|
| 1166 | struct mm_struct *mm_alloc(void)
|
| 1167 | {
|
| 1168 | struct mm_struct *mm;
|
| 1169 |
|
| 1170 | mm = allocate_mm();
|
| 1171 | if (!mm)
|
| 1172 | return NULL;
|
| 1173 |
|
| 1174 | memset(mm, 0, sizeof(*mm));
|
| 1175 | return mm_init(mm, current);
|
| 1176 | }
|
| 1177 | EXPORT_SYMBOL_IF_KUNIT(mm_alloc);
|
| 1178 |
|
| 1179 | static inline void __mmput(struct mm_struct *mm)
|
| 1180 | {
|
| 1181 | VM_BUG_ON(atomic_read(&mm->mm_users));
|
| 1182 |
|
| 1183 | uprobe_clear_state(mm);
|
| 1184 | exit_aio(mm);
|
| 1185 | ksm_exit(mm);
|
| 1186 | khugepaged_exit(mm);
|
| 1187 | exit_mmap(mm);
|
| 1188 | mm_put_huge_zero_folio(mm);
|
| 1189 | set_mm_exe_file(mm, NULL);
|
| 1190 | if (!list_empty(&mm->mmlist)) {
|
| 1191 | spin_lock(&mmlist_lock);
|
| 1192 | list_del(&mm->mmlist);
|
| 1193 | spin_unlock(&mmlist_lock);
|
| 1194 | }
|
| 1195 | if (mm->binfmt)
|
| 1196 | module_put(mm->binfmt->module);
|
| 1197 | lru_gen_del_mm(mm);
|
| 1198 | futex_hash_free(mm);
|
| 1199 | mmdrop(mm);
|
| 1200 | }
|
| 1201 |
|
| 1202 | |
| 1203 | * Decrement the use count and release all resources for an mm.
|
| 1204 |
|
| 1205 | void mmput(struct mm_struct *mm)
|
| 1206 | {
|
| 1207 | might_sleep();
|
| 1208 |
|
| 1209 | if (atomic_dec_and_test(&mm->mm_users))
|
| 1210 | __mmput(mm);
|
| 1211 | }
|
| 1212 | EXPORT_SYMBOL_GPL(mmput);
|
| 1213 |
|
| 1214 | #if defined(CONFIG_MMU) || defined(CONFIG_FUTEX_PRIVATE_HASH)
|
| 1215 | static void mmput_async_fn(struct work_struct *work)
|
| 1216 | {
|
| 1217 | struct mm_struct *mm = container_of(work, struct mm_struct,
|
| 1218 | async_put_work);
|
| 1219 |
|
| 1220 | __mmput(mm);
|
| 1221 | }
|
| 1222 |
|
| 1223 | void mmput_async(struct mm_struct *mm)
|
| 1224 | {
|
| 1225 | if (atomic_dec_and_test(&mm->mm_users)) {
|
| 1226 | INIT_WORK(&mm->async_put_work, mmput_async_fn);
|
| 1227 | schedule_work(&mm->async_put_work);
|
| 1228 | }
|
| 1229 | }
|
| 1230 | EXPORT_SYMBOL_GPL(mmput_async);
|
| 1231 | #endif
|
| 1232 |
|
| 1233 | |
| 1234 | * set_mm_exe_file - change a reference to the mm's executable file
|
| 1235 | * @mm: The mm to change.
|
| 1236 | * @new_exe_file: The new file to use.
|
| 1237 | *
|
| 1238 | * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
|
| 1239 | *
|
| 1240 | * Main users are mmput() and sys_execve(). Callers prevent concurrent
|
| 1241 | * invocations: in mmput() nobody alive left, in execve it happens before
|
| 1242 | * the new mm is made visible to anyone.
|
| 1243 | *
|
| 1244 | * Can only fail if new_exe_file != NULL.
|
| 1245 |
|
| 1246 | int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
|
| 1247 | {
|
| 1248 | struct file *old_exe_file;
|
| 1249 |
|
| 1250 | |
| 1251 | * It is safe to dereference the exe_file without RCU as
|
| 1252 | * this function is only called if nobody else can access
|
| 1253 | * this mm -- see comment above for justification.
|
| 1254 |
|
| 1255 | old_exe_file = rcu_dereference_raw(mm->exe_file);
|
| 1256 |
|
| 1257 | if (new_exe_file) {
|
| 1258 | |
| 1259 | * We expect the caller (i.e., sys_execve) to already denied
|
| 1260 | * write access, so this is unlikely to fail.
|
| 1261 |
|
| 1262 | if (unlikely(exe_file_deny_write_access(new_exe_file)))
|
| 1263 | return -EACCES;
|
| 1264 | get_file(new_exe_file);
|
| 1265 | }
|
| 1266 | rcu_assign_pointer(mm->exe_file, new_exe_file);
|
| 1267 | if (old_exe_file) {
|
| 1268 | exe_file_allow_write_access(old_exe_file);
|
| 1269 | fput(old_exe_file);
|
| 1270 | }
|
| 1271 | return 0;
|
| 1272 | }
|
| 1273 |
|
| 1274 | |
| 1275 | * replace_mm_exe_file - replace a reference to the mm's executable file
|
| 1276 | * @mm: The mm to change.
|
| 1277 | * @new_exe_file: The new file to use.
|
| 1278 | *
|
| 1279 | * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
|
| 1280 | *
|
| 1281 | * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
|
| 1282 |
|
| 1283 | int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
|
| 1284 | {
|
| 1285 | struct vm_area_struct *vma;
|
| 1286 | struct file *old_exe_file;
|
| 1287 | int ret = 0;
|
| 1288 |
|
| 1289 |
|
| 1290 | old_exe_file = get_mm_exe_file(mm);
|
| 1291 | if (old_exe_file) {
|
| 1292 | VMA_ITERATOR(vmi, mm, 0);
|
| 1293 | mmap_read_lock(mm);
|
| 1294 | for_each_vma(vmi, vma) {
|
| 1295 | if (!vma->vm_file)
|
| 1296 | continue;
|
| 1297 | if (path_equal(&vma->vm_file->f_path,
|
| 1298 | &old_exe_file->f_path)) {
|
| 1299 | ret = -EBUSY;
|
| 1300 | break;
|
| 1301 | }
|
| 1302 | }
|
| 1303 | mmap_read_unlock(mm);
|
| 1304 | fput(old_exe_file);
|
| 1305 | if (ret)
|
| 1306 | return ret;
|
| 1307 | }
|
| 1308 |
|
| 1309 | ret = exe_file_deny_write_access(new_exe_file);
|
| 1310 | if (ret)
|
| 1311 | return -EACCES;
|
| 1312 | get_file(new_exe_file);
|
| 1313 |
|
| 1314 |
|
| 1315 | mmap_write_lock(mm);
|
| 1316 | old_exe_file = rcu_dereference_raw(mm->exe_file);
|
| 1317 | rcu_assign_pointer(mm->exe_file, new_exe_file);
|
| 1318 | mmap_write_unlock(mm);
|
| 1319 |
|
| 1320 | if (old_exe_file) {
|
| 1321 | exe_file_allow_write_access(old_exe_file);
|
| 1322 | fput(old_exe_file);
|
| 1323 | }
|
| 1324 | return 0;
|
| 1325 | }
|
| 1326 |
|
| 1327 | |
| 1328 | * get_mm_exe_file - acquire a reference to the mm's executable file
|
| 1329 | * @mm: The mm of interest.
|
| 1330 | *
|
| 1331 | * Returns %NULL if mm has no associated executable file.
|
| 1332 | * User must release file via fput().
|
| 1333 |
|
| 1334 | struct file *get_mm_exe_file(struct mm_struct *mm)
|
| 1335 | {
|
| 1336 | struct file *exe_file;
|
| 1337 |
|
| 1338 | rcu_read_lock();
|
| 1339 | exe_file = get_file_rcu(&mm->exe_file);
|
| 1340 | rcu_read_unlock();
|
| 1341 | return exe_file;
|
| 1342 | }
|
| 1343 |
|
| 1344 | |
| 1345 | * get_task_exe_file - acquire a reference to the task's executable file
|
| 1346 | * @task: The task.
|
| 1347 | *
|
| 1348 | * Returns %NULL if task's mm (if any) has no associated executable file or
|
| 1349 | * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
|
| 1350 | * User must release file via fput().
|
| 1351 |
|
| 1352 | struct file *get_task_exe_file(struct task_struct *task)
|
| 1353 | {
|
| 1354 | struct file *exe_file = NULL;
|
| 1355 | struct mm_struct *mm;
|
| 1356 |
|
| 1357 | if (task->flags & PF_KTHREAD)
|
| 1358 | return NULL;
|
| 1359 |
|
| 1360 | task_lock(task);
|
| 1361 | mm = task->mm;
|
| 1362 | if (mm)
|
| 1363 | exe_file = get_mm_exe_file(mm);
|
| 1364 | task_unlock(task);
|
| 1365 | return exe_file;
|
| 1366 | }
|
| 1367 |
|
| 1368 | |
| 1369 | * get_task_mm - acquire a reference to the task's mm
|
| 1370 | * @task: The task.
|
| 1371 | *
|
| 1372 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
|
| 1373 | * this kernel workthread has transiently adopted a user mm with kthread_use_mm,
|
| 1374 | * to do its AIO) is not set and if so returns a reference to it, after
|
| 1375 | * bumping up the use count. User must release the mm via mmput()
|
| 1376 | * after use. Typically used by /proc and ptrace.
|
| 1377 |
|
| 1378 | struct mm_struct *get_task_mm(struct task_struct *task)
|
| 1379 | {
|
| 1380 | struct mm_struct *mm;
|
| 1381 |
|
| 1382 | if (task->flags & PF_KTHREAD)
|
| 1383 | return NULL;
|
| 1384 |
|
| 1385 | task_lock(task);
|
| 1386 | mm = task->mm;
|
| 1387 | if (mm)
|
| 1388 | mmget(mm);
|
| 1389 | task_unlock(task);
|
| 1390 | return mm;
|
| 1391 | }
|
| 1392 | EXPORT_SYMBOL_GPL(get_task_mm);
|
| 1393 |
|
| 1394 | static bool may_access_mm(struct mm_struct *mm, struct task_struct *task, unsigned int mode)
|
| 1395 | {
|
| 1396 | if (mm == current->mm)
|
| 1397 | return true;
|
| 1398 | if (ptrace_may_access(task, mode))
|
| 1399 | return true;
|
| 1400 | if ((mode & PTRACE_MODE_READ) && perfmon_capable())
|
| 1401 | return true;
|
| 1402 | return false;
|
| 1403 | }
|
| 1404 |
|
| 1405 | struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
|
| 1406 | {
|
| 1407 | struct mm_struct *mm;
|
| 1408 | int err;
|
| 1409 |
|
| 1410 | err = down_read_killable(&task->signal->exec_update_lock);
|
| 1411 | if (err)
|
| 1412 | return ERR_PTR(err);
|
| 1413 |
|
| 1414 | mm = get_task_mm(task);
|
| 1415 | if (!mm) {
|
| 1416 | mm = ERR_PTR(-ESRCH);
|
| 1417 | } else if (!may_access_mm(mm, task, mode)) {
|
| 1418 | mmput(mm);
|
| 1419 | mm = ERR_PTR(-EACCES);
|
| 1420 | }
|
| 1421 | up_read(&task->signal->exec_update_lock);
|
| 1422 |
|
| 1423 | return mm;
|
| 1424 | }
|
| 1425 |
|
| 1426 | static void complete_vfork_done(struct task_struct *tsk)
|
| 1427 | {
|
| 1428 | struct completion *vfork;
|
| 1429 |
|
| 1430 | task_lock(tsk);
|
| 1431 | vfork = tsk->vfork_done;
|
| 1432 | if (likely(vfork)) {
|
| 1433 | tsk->vfork_done = NULL;
|
| 1434 | complete(vfork);
|
| 1435 | }
|
| 1436 | task_unlock(tsk);
|
| 1437 | }
|
| 1438 |
|
| 1439 | static int wait_for_vfork_done(struct task_struct *child,
|
| 1440 | struct completion *vfork)
|
| 1441 | {
|
| 1442 | unsigned int state = TASK_KILLABLE|TASK_FREEZABLE;
|
| 1443 | int killed;
|
| 1444 |
|
| 1445 | cgroup_enter_frozen();
|
| 1446 | killed = wait_for_completion_state(vfork, state);
|
| 1447 | cgroup_leave_frozen(false);
|
| 1448 |
|
| 1449 | if (killed) {
|
| 1450 | task_lock(child);
|
| 1451 | child->vfork_done = NULL;
|
| 1452 | task_unlock(child);
|
| 1453 | }
|
| 1454 |
|
| 1455 | put_task_struct(child);
|
| 1456 | return killed;
|
| 1457 | }
|
| 1458 |
|
| 1459 | |
| 1460 | * mmput is called whenever we stop holding onto a mm_struct,
|
| 1461 | * error success whatever.
|
| 1462 | *
|
| 1463 | * mm_release is called after a mm_struct has been removed
|
| 1464 | * from the current process.
|
| 1465 | *
|
| 1466 | * This difference is important for error handling, when we
|
| 1467 | * only half set up a mm_struct for a new process and need to restore
|
| 1468 | * the old one. Because we mmput the new mm_struct before
|
| 1469 | * restoring the old one. . .
|
| 1470 | * Eric Biederman 10 January 1998
|
| 1471 |
|
| 1472 | static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
| 1473 | {
|
| 1474 | uprobe_free_utask(tsk);
|
| 1475 |
|
| 1476 |
|
| 1477 | deactivate_mm(tsk, mm);
|
| 1478 |
|
| 1479 | |
| 1480 | * Signal userspace if we're not exiting with a core dump
|
| 1481 | * because we want to leave the value intact for debugging
|
| 1482 | * purposes.
|
| 1483 |
|
| 1484 | if (tsk->clear_child_tid) {
|
| 1485 | if (atomic_read(&mm->mm_users) > 1) {
|
| 1486 | |
| 1487 | * We don't check the error code - if userspace has
|
| 1488 | * not set up a proper pointer then tough luck.
|
| 1489 |
|
| 1490 | put_user(0, tsk->clear_child_tid);
|
| 1491 | do_futex(tsk->clear_child_tid, FUTEX_WAKE,
|
| 1492 | 1, NULL, NULL, 0, 0);
|
| 1493 | }
|
| 1494 | tsk->clear_child_tid = NULL;
|
| 1495 | }
|
| 1496 |
|
| 1497 | |
| 1498 | * All done, finally we can wake up parent and return this mm to him.
|
| 1499 | * Also kthread_stop() uses this completion for synchronization.
|
| 1500 |
|
| 1501 | if (tsk->vfork_done)
|
| 1502 | complete_vfork_done(tsk);
|
| 1503 | }
|
| 1504 |
|
| 1505 | void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
| 1506 | {
|
| 1507 | futex_exit_release(tsk);
|
| 1508 | mm_release(tsk, mm);
|
| 1509 | }
|
| 1510 |
|
| 1511 | void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
| 1512 | {
|
| 1513 | futex_exec_release(tsk);
|
| 1514 | mm_release(tsk, mm);
|
| 1515 | }
|
| 1516 |
|
| 1517 | |
| 1518 | * dup_mm() - duplicates an existing mm structure
|
| 1519 | * @tsk: the task_struct with which the new mm will be associated.
|
| 1520 | * @oldmm: the mm to duplicate.
|
| 1521 | *
|
| 1522 | * Allocates a new mm structure and duplicates the provided @oldmm structure
|
| 1523 | * content into it.
|
| 1524 | *
|
| 1525 | * Return: the duplicated mm or NULL on failure.
|
| 1526 |
|
| 1527 | static struct mm_struct *dup_mm(struct task_struct *tsk,
|
| 1528 | struct mm_struct *oldmm)
|
| 1529 | {
|
| 1530 | struct mm_struct *mm;
|
| 1531 | int err;
|
| 1532 |
|
| 1533 | mm = allocate_mm();
|
| 1534 | if (!mm)
|
| 1535 | goto fail_nomem;
|
| 1536 |
|
| 1537 | memcpy(mm, oldmm, sizeof(*mm));
|
| 1538 |
|
| 1539 | if (!mm_init(mm, tsk))
|
| 1540 | goto fail_nomem;
|
| 1541 |
|
| 1542 | uprobe_start_dup_mmap();
|
| 1543 | err = dup_mmap(mm, oldmm);
|
| 1544 | if (err)
|
| 1545 | goto free_pt;
|
| 1546 | uprobe_end_dup_mmap();
|
| 1547 |
|
| 1548 | mm->hiwater_rss = get_mm_rss(mm);
|
| 1549 | mm->hiwater_vm = mm->total_vm;
|
| 1550 |
|
| 1551 | if (mm->binfmt && !try_module_get(mm->binfmt->module))
|
| 1552 | goto free_pt;
|
| 1553 |
|
| 1554 | return mm;
|
| 1555 |
|
| 1556 | free_pt:
|
| 1557 |
|
| 1558 | mm->binfmt = NULL;
|
| 1559 | mm_init_owner(mm, NULL);
|
| 1560 | mmput(mm);
|
| 1561 | if (err)
|
| 1562 | uprobe_end_dup_mmap();
|
| 1563 |
|
| 1564 | fail_nomem:
|
| 1565 | return NULL;
|
| 1566 | }
|
| 1567 |
|
| 1568 | static int copy_mm(u64 clone_flags, struct task_struct *tsk)
|
| 1569 | {
|
| 1570 | struct mm_struct *mm, *oldmm;
|
| 1571 |
|
| 1572 | tsk->min_flt = tsk->maj_flt = 0;
|
| 1573 | tsk->nvcsw = tsk->nivcsw = 0;
|
| 1574 | #ifdef CONFIG_DETECT_HUNG_TASK
|
| 1575 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
|
| 1576 | tsk->last_switch_time = 0;
|
| 1577 | #endif
|
| 1578 |
|
| 1579 | tsk->mm = NULL;
|
| 1580 | tsk->active_mm = NULL;
|
| 1581 |
|
| 1582 | |
| 1583 | * Are we cloning a kernel thread?
|
| 1584 | *
|
| 1585 | * We need to steal a active VM for that..
|
| 1586 |
|
| 1587 | oldmm = current->mm;
|
| 1588 | if (!oldmm)
|
| 1589 | return 0;
|
| 1590 |
|
| 1591 | if (clone_flags & CLONE_VM) {
|
| 1592 | mmget(oldmm);
|
| 1593 | mm = oldmm;
|
| 1594 | } else {
|
| 1595 | mm = dup_mm(tsk, current->mm);
|
| 1596 | if (!mm)
|
| 1597 | return -ENOMEM;
|
| 1598 | }
|
| 1599 |
|
| 1600 | tsk->mm = mm;
|
| 1601 | tsk->active_mm = mm;
|
| 1602 | return 0;
|
| 1603 | }
|
| 1604 |
|
| 1605 | static int copy_exec_state(u64 clone_flags, struct task_struct *tsk)
|
| 1606 | {
|
| 1607 | struct task_exec_state *exec_state;
|
| 1608 |
|
| 1609 |
|
| 1610 | if (clone_flags & CLONE_VM) {
|
| 1611 | exec_state = rcu_dereference_protected(current->exec_state, true);
|
| 1612 | refcount_inc(&exec_state->count);
|
| 1613 | rcu_assign_pointer(tsk->exec_state, exec_state);
|
| 1614 | return 0;
|
| 1615 | }
|
| 1616 |
|
| 1617 |
|
| 1618 | return task_exec_state_copy(tsk);
|
| 1619 | }
|
| 1620 |
|
| 1621 | static int copy_fs(u64 clone_flags, struct task_struct *tsk)
|
| 1622 | {
|
| 1623 | struct fs_struct *fs = current->fs;
|
| 1624 | if (clone_flags & CLONE_FS) {
|
| 1625 |
|
| 1626 | read_seqlock_excl(&fs->seq);
|
| 1627 |
|
| 1628 | if (fs->in_exec) {
|
| 1629 | read_sequnlock_excl(&fs->seq);
|
| 1630 | return -EAGAIN;
|
| 1631 | }
|
| 1632 | fs->users++;
|
| 1633 | read_sequnlock_excl(&fs->seq);
|
| 1634 | return 0;
|
| 1635 | }
|
| 1636 | tsk->fs = copy_fs_struct(fs);
|
| 1637 | if (!tsk->fs)
|
| 1638 | return -ENOMEM;
|
| 1639 | return 0;
|
| 1640 | }
|
| 1641 |
|
| 1642 | static int copy_files(u64 clone_flags, struct task_struct *tsk,
|
| 1643 | int no_files)
|
| 1644 | {
|
| 1645 | struct files_struct *oldf, *newf;
|
| 1646 |
|
| 1647 | |
| 1648 | * A background process may not have any files ...
|
| 1649 |
|
| 1650 | oldf = current->files;
|
| 1651 | if (!oldf)
|
| 1652 | return 0;
|
| 1653 |
|
| 1654 | if (no_files) {
|
| 1655 | tsk->files = NULL;
|
| 1656 | return 0;
|
| 1657 | }
|
| 1658 |
|
| 1659 | if (clone_flags & CLONE_FILES) {
|
| 1660 | atomic_inc(&oldf->count);
|
| 1661 | return 0;
|
| 1662 | }
|
| 1663 |
|
| 1664 | newf = dup_fd(oldf, NULL);
|
| 1665 | if (IS_ERR(newf))
|
| 1666 | return PTR_ERR(newf);
|
| 1667 |
|
| 1668 | tsk->files = newf;
|
| 1669 | return 0;
|
| 1670 | }
|
| 1671 |
|
| 1672 | static int copy_sighand(u64 clone_flags, struct task_struct *tsk)
|
| 1673 | {
|
| 1674 | struct sighand_struct *sig;
|
| 1675 |
|
| 1676 | if (clone_flags & CLONE_SIGHAND) {
|
| 1677 | refcount_inc(¤t->sighand->count);
|
| 1678 | return 0;
|
| 1679 | }
|
| 1680 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
|
| 1681 | RCU_INIT_POINTER(tsk->sighand, sig);
|
| 1682 | if (!sig)
|
| 1683 | return -ENOMEM;
|
| 1684 |
|
| 1685 | refcount_set(&sig->count, 1);
|
| 1686 | spin_lock_irq(¤t->sighand->siglock);
|
| 1687 | memcpy(sig->action, current->sighand->action, sizeof(sig->action));
|
| 1688 | spin_unlock_irq(¤t->sighand->siglock);
|
| 1689 |
|
| 1690 |
|
| 1691 | if (clone_flags & CLONE_CLEAR_SIGHAND)
|
| 1692 | flush_signal_handlers(tsk, 0);
|
| 1693 |
|
| 1694 | return 0;
|
| 1695 | }
|
| 1696 |
|
| 1697 | void __cleanup_sighand(struct sighand_struct *sighand)
|
| 1698 | {
|
| 1699 | if (refcount_dec_and_test(&sighand->count)) {
|
| 1700 | signalfd_cleanup(sighand);
|
| 1701 | |
| 1702 | * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
|
| 1703 | * without an RCU grace period, see __lock_task_sighand().
|
| 1704 |
|
| 1705 | kmem_cache_free(sighand_cachep, sighand);
|
| 1706 | }
|
| 1707 | }
|
| 1708 |
|
| 1709 | |
| 1710 | * Initialize POSIX timer handling for a thread group.
|
| 1711 |
|
| 1712 | static void posix_cpu_timers_init_group(struct signal_struct *sig)
|
| 1713 | {
|
| 1714 | struct posix_cputimers *pct = &sig->posix_cputimers;
|
| 1715 | unsigned long cpu_limit;
|
| 1716 |
|
| 1717 | cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
|
| 1718 | posix_cputimers_group_init(pct, cpu_limit);
|
| 1719 | }
|
| 1720 |
|
| 1721 | static int copy_signal(u64 clone_flags, struct task_struct *tsk)
|
| 1722 | {
|
| 1723 | struct signal_struct *sig;
|
| 1724 |
|
| 1725 | if (clone_flags & CLONE_THREAD)
|
| 1726 | return 0;
|
| 1727 |
|
| 1728 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
|
| 1729 | tsk->signal = sig;
|
| 1730 | if (!sig)
|
| 1731 | return -ENOMEM;
|
| 1732 |
|
| 1733 | sig->nr_threads = 1;
|
| 1734 | sig->quick_threads = 1;
|
| 1735 | atomic_set(&sig->live, 1);
|
| 1736 | refcount_set(&sig->sigcnt, 1);
|
| 1737 |
|
| 1738 |
|
| 1739 | sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
|
| 1740 | tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
|
| 1741 |
|
| 1742 | init_waitqueue_head(&sig->wait_chldexit);
|
| 1743 | sig->curr_target = tsk;
|
| 1744 | init_sigpending(&sig->shared_pending);
|
| 1745 | INIT_HLIST_HEAD(&sig->multiprocess);
|
| 1746 | seqlock_init(&sig->stats_lock);
|
| 1747 | prev_cputime_init(&sig->prev_cputime);
|
| 1748 |
|
| 1749 | #ifdef CONFIG_POSIX_TIMERS
|
| 1750 | INIT_HLIST_HEAD(&sig->posix_timers);
|
| 1751 | INIT_HLIST_HEAD(&sig->ignored_posix_timers);
|
| 1752 | hrtimer_setup(&sig->real_timer, it_real_fn, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
| 1753 | #endif
|
| 1754 |
|
| 1755 | task_lock(current->group_leader);
|
| 1756 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
|
| 1757 | task_unlock(current->group_leader);
|
| 1758 |
|
| 1759 | posix_cpu_timers_init_group(sig);
|
| 1760 |
|
| 1761 | tty_audit_fork(sig);
|
| 1762 | sched_autogroup_fork(sig);
|
| 1763 |
|
| 1764 | #ifdef CONFIG_CGROUPS
|
| 1765 | init_rwsem(&sig->cgroup_threadgroup_rwsem);
|
| 1766 | #endif
|
| 1767 |
|
| 1768 | sig->oom_score_adj = current->signal->oom_score_adj;
|
| 1769 | sig->oom_score_adj_min = current->signal->oom_score_adj_min;
|
| 1770 |
|
| 1771 | mutex_init(&sig->cred_guard_mutex);
|
| 1772 | init_rwsem(&sig->exec_update_lock);
|
| 1773 |
|
| 1774 | return 0;
|
| 1775 | }
|
| 1776 |
|
| 1777 | static void copy_seccomp(struct task_struct *p)
|
| 1778 | {
|
| 1779 | #ifdef CONFIG_SECCOMP
|
| 1780 | |
| 1781 | * Must be called with sighand->lock held, which is common to
|
| 1782 | * all threads in the group. Holding cred_guard_mutex is not
|
| 1783 | * needed because this new task is not yet running and cannot
|
| 1784 | * be racing exec.
|
| 1785 |
|
| 1786 | assert_spin_locked(¤t->sighand->siglock);
|
| 1787 |
|
| 1788 |
|
| 1789 | get_seccomp_filter(current);
|
| 1790 | p->seccomp = current->seccomp;
|
| 1791 |
|
| 1792 | |
| 1793 | * Explicitly enable no_new_privs here in case it got set
|
| 1794 | * between the task_struct being duplicated and holding the
|
| 1795 | * sighand lock. The seccomp state and nnp must be in sync.
|
| 1796 |
|
| 1797 | if (task_no_new_privs(current))
|
| 1798 | task_set_no_new_privs(p);
|
| 1799 |
|
| 1800 | |
| 1801 | * If the parent gained a seccomp mode after copying thread
|
| 1802 | * flags and between before we held the sighand lock, we have
|
| 1803 | * to manually enable the seccomp thread flag here.
|
| 1804 |
|
| 1805 | if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
|
| 1806 | set_task_syscall_work(p, SECCOMP);
|
| 1807 | #endif
|
| 1808 | }
|
| 1809 |
|
| 1810 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
|
| 1811 | {
|
| 1812 | current->clear_child_tid = tidptr;
|
| 1813 |
|
| 1814 | return task_pid_vnr(current);
|
| 1815 | }
|
| 1816 |
|
| 1817 | static void rt_mutex_init_task(struct task_struct *p)
|
| 1818 | {
|
| 1819 | raw_spin_lock_init(&p->pi_lock);
|
| 1820 | #ifdef CONFIG_RT_MUTEXES
|
| 1821 | p->pi_waiters = RB_ROOT_CACHED;
|
| 1822 | p->pi_top_task = NULL;
|
| 1823 | p->pi_blocked_on = NULL;
|
| 1824 | #endif
|
| 1825 | }
|
| 1826 |
|
| 1827 | static inline void init_task_pid_links(struct task_struct *task)
|
| 1828 | {
|
| 1829 | enum pid_type type;
|
| 1830 |
|
| 1831 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
|
| 1832 | INIT_HLIST_NODE(&task->pid_links[type]);
|
| 1833 | }
|
| 1834 |
|
| 1835 | static inline void
|
| 1836 | init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
|
| 1837 | {
|
| 1838 | if (type == PIDTYPE_PID)
|
| 1839 | task->thread_pid = pid;
|
| 1840 | else
|
| 1841 | task->signal->pids[type] = pid;
|
| 1842 | }
|
| 1843 |
|
| 1844 | static inline void rcu_copy_process(struct task_struct *p)
|
| 1845 | {
|
| 1846 | #ifdef CONFIG_PREEMPT_RCU
|
| 1847 | p->rcu_read_lock_nesting = 0;
|
| 1848 | p->rcu_read_unlock_special.s = 0;
|
| 1849 | p->rcu_blocked_node = NULL;
|
| 1850 | INIT_LIST_HEAD(&p->rcu_node_entry);
|
| 1851 | #endif
|
| 1852 | #ifdef CONFIG_TASKS_RCU
|
| 1853 | p->rcu_tasks_holdout = false;
|
| 1854 | INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
|
| 1855 | p->rcu_tasks_idle_cpu = -1;
|
| 1856 | INIT_LIST_HEAD(&p->rcu_tasks_exit_list);
|
| 1857 | #endif
|
| 1858 | #ifdef CONFIG_TASKS_TRACE_RCU
|
| 1859 | p->trc_reader_nesting = 0;
|
| 1860 | #endif
|
| 1861 | }
|
| 1862 |
|
| 1863 | |
| 1864 | * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
|
| 1865 | * @pid: the struct pid for which to create a pidfd
|
| 1866 | * @flags: flags of the new @pidfd
|
| 1867 | * @ret_file: return the new pidfs file
|
| 1868 | *
|
| 1869 | * Allocate a new file that stashes @pid and reserve a new pidfd number in the
|
| 1870 | * caller's file descriptor table. The pidfd is reserved but not installed yet.
|
| 1871 | *
|
| 1872 | * The helper verifies that @pid is still in use, without PIDFD_THREAD the
|
| 1873 | * task identified by @pid must be a thread-group leader.
|
| 1874 | *
|
| 1875 | * If this function returns successfully the caller is responsible to either
|
| 1876 | * call fd_install() passing the returned pidfd and pidfd file as arguments in
|
| 1877 | * order to install the pidfd into its file descriptor table or they must use
|
| 1878 | * put_unused_fd() and fput() on the returned pidfd and pidfd file
|
| 1879 | * respectively.
|
| 1880 | *
|
| 1881 | * This function is useful when a pidfd must already be reserved but there
|
| 1882 | * might still be points of failure afterwards and the caller wants to ensure
|
| 1883 | * that no pidfd is leaked into its file descriptor table.
|
| 1884 | *
|
| 1885 | * Return: On success, a reserved pidfd is returned from the function and a new
|
| 1886 | * pidfd file is returned in the last argument to the function. On
|
| 1887 | * error, a negative error code is returned from the function and the
|
| 1888 | * last argument remains unchanged.
|
| 1889 |
|
| 1890 | int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret_file)
|
| 1891 | {
|
| 1892 | struct file *pidfs_file;
|
| 1893 |
|
| 1894 | |
| 1895 | * PIDFD_STALE is only allowed to be passed if the caller knows
|
| 1896 | * that @pid is already registered in pidfs and thus
|
| 1897 | * PIDFD_INFO_EXIT information is guaranteed to be available.
|
| 1898 |
|
| 1899 | if (!(flags & PIDFD_STALE)) {
|
| 1900 | |
| 1901 | * While holding the pidfd waitqueue lock removing the
|
| 1902 | * task linkage for the thread-group leader pid
|
| 1903 | * (PIDTYPE_TGID) isn't possible. Thus, if there's still
|
| 1904 | * task linkage for PIDTYPE_PID not having thread-group
|
| 1905 | * leader linkage for the pid means it wasn't a
|
| 1906 | * thread-group leader in the first place.
|
| 1907 |
|
| 1908 | guard(spinlock_irq)(&pid->wait_pidfd.lock);
|
| 1909 |
|
| 1910 |
|
| 1911 | if (!pid_has_task(pid, PIDTYPE_PID))
|
| 1912 | return -ESRCH;
|
| 1913 | |
| 1914 | * If this struct pid isn't used as a thread-group
|
| 1915 | * leader but the caller requested to create a
|
| 1916 | * thread-group leader pidfd then report ENOENT.
|
| 1917 |
|
| 1918 | if (!(flags & PIDFD_THREAD) && !pid_has_task(pid, PIDTYPE_TGID))
|
| 1919 | return -ENOENT;
|
| 1920 | }
|
| 1921 |
|
| 1922 | CLASS(get_unused_fd, pidfd)(O_CLOEXEC);
|
| 1923 | if (pidfd < 0)
|
| 1924 | return pidfd;
|
| 1925 |
|
| 1926 | pidfs_file = pidfs_alloc_file(pid, flags | O_RDWR);
|
| 1927 | if (IS_ERR(pidfs_file))
|
| 1928 | return PTR_ERR(pidfs_file);
|
| 1929 |
|
| 1930 | *ret_file = pidfs_file;
|
| 1931 | return take_fd(pidfd);
|
| 1932 | }
|
| 1933 |
|
| 1934 | static void __delayed_free_task(struct rcu_head *rhp)
|
| 1935 | {
|
| 1936 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
|
| 1937 |
|
| 1938 | free_task(tsk);
|
| 1939 | }
|
| 1940 |
|
| 1941 | static __always_inline void delayed_free_task(struct task_struct *tsk)
|
| 1942 | {
|
| 1943 | if (IS_ENABLED(CONFIG_MEMCG))
|
| 1944 | call_rcu(&tsk->rcu, __delayed_free_task);
|
| 1945 | else
|
| 1946 | free_task(tsk);
|
| 1947 | }
|
| 1948 |
|
| 1949 | static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
|
| 1950 | {
|
| 1951 |
|
| 1952 | if (!tsk->mm)
|
| 1953 | return;
|
| 1954 |
|
| 1955 |
|
| 1956 | if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
|
| 1957 | return;
|
| 1958 |
|
| 1959 |
|
| 1960 | mutex_lock(&oom_adj_mutex);
|
| 1961 | mm_flags_set(MMF_MULTIPROCESS, tsk->mm);
|
| 1962 |
|
| 1963 | tsk->signal->oom_score_adj = current->signal->oom_score_adj;
|
| 1964 | tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
|
| 1965 | mutex_unlock(&oom_adj_mutex);
|
| 1966 | }
|
| 1967 |
|
| 1968 | #ifdef CONFIG_RV
|
| 1969 | static void rv_task_fork(struct task_struct *p)
|
| 1970 | {
|
| 1971 | memset(&p->rv, 0, sizeof(p->rv));
|
| 1972 | }
|
| 1973 | #else
|
| 1974 | #define rv_task_fork(p) do {} while (0)
|
| 1975 | #endif
|
| 1976 |
|
| 1977 | static bool need_futex_hash_allocate_default(u64 clone_flags)
|
| 1978 | {
|
| 1979 | |
| 1980 | * Allocate a default futex hash for any sibling that will
|
| 1981 | * share the parent's mm, except vfork.
|
| 1982 |
|
| 1983 | return (clone_flags & (CLONE_VM | CLONE_VFORK)) == CLONE_VM;
|
| 1984 | }
|
| 1985 |
|
| 1986 | |
| 1987 | * This creates a new process as a copy of the old one,
|
| 1988 | * but does not actually start it yet.
|
| 1989 | *
|
| 1990 | * It copies the registers, and all the appropriate
|
| 1991 | * parts of the process environment (as per the clone
|
| 1992 | * flags). The actual kick-off is left to the caller.
|
| 1993 |
|
| 1994 | __latent_entropy struct task_struct *copy_process(
|
| 1995 | struct pid *pid,
|
| 1996 | int trace,
|
| 1997 | int node,
|
| 1998 | struct kernel_clone_args *args)
|
| 1999 | {
|
| 2000 | int pidfd = -1, retval;
|
| 2001 | struct task_struct *p;
|
| 2002 | struct multiprocess_signals delayed;
|
| 2003 | struct file *pidfile = NULL;
|
| 2004 | const u64 clone_flags = args->flags;
|
| 2005 | struct nsproxy *nsp = current->nsproxy;
|
| 2006 |
|
| 2007 | |
| 2008 | * Don't allow sharing the root directory with processes in a different
|
| 2009 | * namespace
|
| 2010 |
|
| 2011 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
|
| 2012 | return ERR_PTR(-EINVAL);
|
| 2013 |
|
| 2014 | if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
|
| 2015 | return ERR_PTR(-EINVAL);
|
| 2016 |
|
| 2017 | |
| 2018 | * Thread groups must share signals as well, and detached threads
|
| 2019 | * can only be started up within the thread group.
|
| 2020 |
|
| 2021 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
|
| 2022 | return ERR_PTR(-EINVAL);
|
| 2023 |
|
| 2024 | |
| 2025 | * Shared signal handlers imply shared VM. By way of the above,
|
| 2026 | * thread groups also imply shared VM. Blocking this case allows
|
| 2027 | * for various simplifications in other code.
|
| 2028 |
|
| 2029 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
|
| 2030 | return ERR_PTR(-EINVAL);
|
| 2031 |
|
| 2032 | |
| 2033 | * Siblings of global init remain as zombies on exit since they are
|
| 2034 | * not reaped by their parent (swapper). To solve this and to avoid
|
| 2035 | * multi-rooted process trees, prevent global and container-inits
|
| 2036 | * from creating siblings.
|
| 2037 |
|
| 2038 | if ((clone_flags & CLONE_PARENT) &&
|
| 2039 | current->signal->flags & SIGNAL_UNKILLABLE)
|
| 2040 | return ERR_PTR(-EINVAL);
|
| 2041 |
|
| 2042 | |
| 2043 | * If the new process will be in a different pid or user namespace
|
| 2044 | * do not allow it to share a thread group with the forking task.
|
| 2045 |
|
| 2046 | if (clone_flags & CLONE_THREAD) {
|
| 2047 | if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
|
| 2048 | (task_active_pid_ns(current) != nsp->pid_ns_for_children))
|
| 2049 | return ERR_PTR(-EINVAL);
|
| 2050 | }
|
| 2051 |
|
| 2052 | if (clone_flags & CLONE_PIDFD) {
|
| 2053 | |
| 2054 | * - CLONE_DETACHED is blocked so that we can potentially
|
| 2055 | * reuse it later for CLONE_PIDFD.
|
| 2056 |
|
| 2057 | if (clone_flags & CLONE_DETACHED)
|
| 2058 | return ERR_PTR(-EINVAL);
|
| 2059 | }
|
| 2060 |
|
| 2061 | if (clone_flags & CLONE_AUTOREAP) {
|
| 2062 | if (clone_flags & CLONE_THREAD)
|
| 2063 | return ERR_PTR(-EINVAL);
|
| 2064 | if (clone_flags & CLONE_PARENT)
|
| 2065 | return ERR_PTR(-EINVAL);
|
| 2066 | if (args->exit_signal)
|
| 2067 | return ERR_PTR(-EINVAL);
|
| 2068 | }
|
| 2069 |
|
| 2070 | if ((clone_flags & CLONE_PARENT) && current->signal->autoreap)
|
| 2071 | return ERR_PTR(-EINVAL);
|
| 2072 |
|
| 2073 | if (clone_flags & CLONE_NNP) {
|
| 2074 | if (clone_flags & CLONE_THREAD)
|
| 2075 | return ERR_PTR(-EINVAL);
|
| 2076 | }
|
| 2077 |
|
| 2078 | if (clone_flags & CLONE_PIDFD_AUTOKILL) {
|
| 2079 | if (!(clone_flags & CLONE_PIDFD))
|
| 2080 | return ERR_PTR(-EINVAL);
|
| 2081 | if (!(clone_flags & CLONE_AUTOREAP))
|
| 2082 | return ERR_PTR(-EINVAL);
|
| 2083 | if (clone_flags & CLONE_THREAD)
|
| 2084 | return ERR_PTR(-EINVAL);
|
| 2085 | |
| 2086 | * Without CLONE_NNP the child could escalate privileges
|
| 2087 | * after being spawned, so require CAP_SYS_ADMIN.
|
| 2088 | * With CLONE_NNP the child can't gain new privileges,
|
| 2089 | * so allow unprivileged usage.
|
| 2090 |
|
| 2091 | if (!(clone_flags & CLONE_NNP) &&
|
| 2092 | !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
|
| 2093 | return ERR_PTR(-EPERM);
|
| 2094 | }
|
| 2095 |
|
| 2096 | |
| 2097 | * Force any signals received before this point to be delivered
|
| 2098 | * before the fork happens. Collect up signals sent to multiple
|
| 2099 | * processes that happen during the fork and delay them so that
|
| 2100 | * they appear to happen after the fork.
|
| 2101 |
|
| 2102 | sigemptyset(&delayed.signal);
|
| 2103 | INIT_HLIST_NODE(&delayed.node);
|
| 2104 |
|
| 2105 | spin_lock_irq(¤t->sighand->siglock);
|
| 2106 | if (!(clone_flags & CLONE_THREAD))
|
| 2107 | hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
|
| 2108 | recalc_sigpending();
|
| 2109 | spin_unlock_irq(¤t->sighand->siglock);
|
| 2110 | retval = -ERESTARTNOINTR;
|
| 2111 | if (task_sigpending(current))
|
| 2112 | goto fork_out;
|
| 2113 |
|
| 2114 | retval = -ENOMEM;
|
| 2115 | p = dup_task_struct(current, node);
|
| 2116 | if (!p)
|
| 2117 | goto fork_out;
|
| 2118 | retval = copy_exec_state(clone_flags, p);
|
| 2119 | if (retval)
|
| 2120 | goto bad_fork_free;
|
| 2121 | p->flags &= ~PF_KTHREAD;
|
| 2122 | if (args->kthread)
|
| 2123 | p->flags |= PF_KTHREAD;
|
| 2124 | if (args->user_worker) {
|
| 2125 | |
| 2126 | * Mark us a user worker, and block any signal that isn't
|
| 2127 | * fatal or STOP
|
| 2128 |
|
| 2129 | p->flags |= PF_USER_WORKER;
|
| 2130 | siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
|
| 2131 | }
|
| 2132 | if (args->io_thread)
|
| 2133 | p->flags |= PF_IO_WORKER;
|
| 2134 |
|
| 2135 | if (args->name)
|
| 2136 | strscpy_pad(p->comm, args->name, sizeof(p->comm));
|
| 2137 |
|
| 2138 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
|
| 2139 | |
| 2140 | * TID is cleared in mm_release() when the task exits
|
| 2141 |
|
| 2142 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
|
| 2143 |
|
| 2144 | ftrace_graph_init_task(p);
|
| 2145 |
|
| 2146 | rt_mutex_init_task(p);
|
| 2147 | raw_spin_lock_init(&p->blocked_lock);
|
| 2148 |
|
| 2149 | lockdep_assert_irqs_enabled();
|
| 2150 | #ifdef CONFIG_PROVE_LOCKING
|
| 2151 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
|
| 2152 | #endif
|
| 2153 | retval = copy_creds(p, clone_flags);
|
| 2154 | if (retval < 0)
|
| 2155 | goto bad_fork_free;
|
| 2156 |
|
| 2157 | retval = -EAGAIN;
|
| 2158 | if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
|
| 2159 | if (p->real_cred->user != INIT_USER &&
|
| 2160 | !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
|
| 2161 | goto bad_fork_cleanup_count;
|
| 2162 | }
|
| 2163 | current->flags &= ~PF_NPROC_EXCEEDED;
|
| 2164 |
|
| 2165 | |
| 2166 | * If multiple threads are within copy_process(), then this check
|
| 2167 | * triggers too late. This doesn't hurt, the check is only there
|
| 2168 | * to stop root fork bombs.
|
| 2169 |
|
| 2170 | retval = -EAGAIN;
|
| 2171 | if (data_race(nr_threads >= max_threads))
|
| 2172 | goto bad_fork_cleanup_count;
|
| 2173 |
|
| 2174 | delayacct_tsk_init(p);
|
| 2175 | p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
|
| 2176 | p->flags |= PF_FORKNOEXEC;
|
| 2177 | INIT_LIST_HEAD(&p->children);
|
| 2178 | INIT_LIST_HEAD(&p->sibling);
|
| 2179 | rcu_copy_process(p);
|
| 2180 | p->vfork_done = NULL;
|
| 2181 | spin_lock_init(&p->alloc_lock);
|
| 2182 |
|
| 2183 | init_sigpending(&p->pending);
|
| 2184 |
|
| 2185 | p->utime = p->stime = p->gtime = 0;
|
| 2186 | #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
|
| 2187 | p->utimescaled = p->stimescaled = 0;
|
| 2188 | #endif
|
| 2189 | prev_cputime_init(&p->prev_cputime);
|
| 2190 |
|
| 2191 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
|
| 2192 | seqcount_init(&p->vtime.seqcount);
|
| 2193 | p->vtime.starttime = 0;
|
| 2194 | p->vtime.state = VTIME_INACTIVE;
|
| 2195 | #endif
|
| 2196 |
|
| 2197 | #ifdef CONFIG_IO_URING
|
| 2198 | p->io_uring = NULL;
|
| 2199 | retval = io_uring_fork(p);
|
| 2200 | if (unlikely(retval))
|
| 2201 | goto bad_fork_cleanup_delayacct;
|
| 2202 | retval = -EAGAIN;
|
| 2203 | #endif
|
| 2204 |
|
| 2205 | p->default_timer_slack_ns = current->timer_slack_ns;
|
| 2206 |
|
| 2207 | #ifdef CONFIG_PSI
|
| 2208 | p->psi_flags = 0;
|
| 2209 | #endif
|
| 2210 |
|
| 2211 | task_io_accounting_init(&p->ioac);
|
| 2212 | acct_clear_integrals(p);
|
| 2213 |
|
| 2214 | posix_cputimers_init(&p->posix_cputimers);
|
| 2215 | tick_dep_init_task(p);
|
| 2216 |
|
| 2217 | p->io_context = NULL;
|
| 2218 | audit_set_context(p, NULL);
|
| 2219 | cgroup_fork(p);
|
| 2220 | if (args->kthread) {
|
| 2221 | if (!set_kthread_struct(p))
|
| 2222 | goto bad_fork_cleanup_delayacct;
|
| 2223 | }
|
| 2224 | #ifdef CONFIG_NUMA
|
| 2225 | p->mempolicy = mpol_dup(p->mempolicy);
|
| 2226 | if (IS_ERR(p->mempolicy)) {
|
| 2227 | retval = PTR_ERR(p->mempolicy);
|
| 2228 | p->mempolicy = NULL;
|
| 2229 | goto bad_fork_cleanup_delayacct;
|
| 2230 | }
|
| 2231 | #endif
|
| 2232 | #ifdef CONFIG_CPUSETS
|
| 2233 | p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
|
| 2234 | seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
|
| 2235 | #endif
|
| 2236 | #ifdef CONFIG_TRACE_IRQFLAGS
|
| 2237 | memset(&p->irqtrace, 0, sizeof(p->irqtrace));
|
| 2238 | p->irqtrace.hardirq_disable_ip = _THIS_IP_;
|
| 2239 | p->irqtrace.softirq_enable_ip = _THIS_IP_;
|
| 2240 | p->softirqs_enabled = 1;
|
| 2241 | p->softirq_context = 0;
|
| 2242 | #endif
|
| 2243 |
|
| 2244 | p->pagefault_disabled = 0;
|
| 2245 |
|
| 2246 | lockdep_init_task(p);
|
| 2247 |
|
| 2248 | p->blocked_on = NULL;
|
| 2249 | p->blocked_donor = NULL;
|
| 2250 |
|
| 2251 | #ifdef CONFIG_BCACHE
|
| 2252 | p->sequential_io = 0;
|
| 2253 | p->sequential_io_avg = 0;
|
| 2254 | #endif
|
| 2255 |
|
| 2256 | unwind_task_init(p);
|
| 2257 |
|
| 2258 |
|
| 2259 | retval = sched_fork(clone_flags, p);
|
| 2260 | if (retval)
|
| 2261 | goto bad_fork_cleanup_policy;
|
| 2262 |
|
| 2263 | retval = perf_event_init_task(p, clone_flags);
|
| 2264 | if (retval)
|
| 2265 | goto bad_fork_sched_cancel_fork;
|
| 2266 | retval = audit_alloc(p);
|
| 2267 | if (retval)
|
| 2268 | goto bad_fork_cleanup_perf;
|
| 2269 |
|
| 2270 | shm_init_task(p);
|
| 2271 | retval = security_task_alloc(p, clone_flags);
|
| 2272 | if (retval)
|
| 2273 | goto bad_fork_cleanup_audit;
|
| 2274 | retval = copy_semundo(clone_flags, p);
|
| 2275 | if (retval)
|
| 2276 | goto bad_fork_cleanup_security;
|
| 2277 | retval = copy_files(clone_flags, p, args->no_files);
|
| 2278 | if (retval)
|
| 2279 | goto bad_fork_cleanup_semundo;
|
| 2280 | retval = copy_fs(clone_flags, p);
|
| 2281 | if (retval)
|
| 2282 | goto bad_fork_cleanup_files;
|
| 2283 | retval = copy_sighand(clone_flags, p);
|
| 2284 | if (retval)
|
| 2285 | goto bad_fork_cleanup_fs;
|
| 2286 | retval = copy_signal(clone_flags, p);
|
| 2287 | if (retval)
|
| 2288 | goto bad_fork_cleanup_sighand;
|
| 2289 | retval = copy_mm(clone_flags, p);
|
| 2290 | if (retval)
|
| 2291 | goto bad_fork_cleanup_signal;
|
| 2292 | retval = copy_namespaces(clone_flags, p);
|
| 2293 | if (retval)
|
| 2294 | goto bad_fork_cleanup_mm;
|
| 2295 | retval = copy_io(clone_flags, p);
|
| 2296 | if (retval)
|
| 2297 | goto bad_fork_cleanup_namespaces;
|
| 2298 | retval = copy_thread(p, args);
|
| 2299 | if (retval)
|
| 2300 | goto bad_fork_cleanup_io;
|
| 2301 |
|
| 2302 | stackleak_task_init(p);
|
| 2303 |
|
| 2304 | if (pid != &init_struct_pid) {
|
| 2305 | pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
|
| 2306 | args->set_tid_size);
|
| 2307 | if (IS_ERR(pid)) {
|
| 2308 | retval = PTR_ERR(pid);
|
| 2309 | goto bad_fork_cleanup_thread;
|
| 2310 | }
|
| 2311 | }
|
| 2312 |
|
| 2313 | |
| 2314 | * This has to happen after we've potentially unshared the file
|
| 2315 | * descriptor table (so that the pidfd doesn't leak into the child
|
| 2316 | * if the fd table isn't shared).
|
| 2317 |
|
| 2318 | if (clone_flags & CLONE_PIDFD) {
|
| 2319 | unsigned flags = PIDFD_STALE;
|
| 2320 |
|
| 2321 | if (clone_flags & CLONE_THREAD)
|
| 2322 | flags |= PIDFD_THREAD;
|
| 2323 | if (clone_flags & CLONE_PIDFD_AUTOKILL)
|
| 2324 | flags |= PIDFD_AUTOKILL;
|
| 2325 |
|
| 2326 | |
| 2327 | * Note that no task has been attached to @pid yet indicate
|
| 2328 | * that via CLONE_PIDFD.
|
| 2329 |
|
| 2330 | retval = pidfd_prepare(pid, flags, &pidfile);
|
| 2331 | if (retval < 0)
|
| 2332 | goto bad_fork_free_pid;
|
| 2333 | pidfd = retval;
|
| 2334 |
|
| 2335 | retval = put_user(pidfd, args->pidfd);
|
| 2336 | if (retval)
|
| 2337 | goto bad_fork_put_pidfd;
|
| 2338 | }
|
| 2339 |
|
| 2340 | #ifdef CONFIG_BLOCK
|
| 2341 | p->plug = NULL;
|
| 2342 | p->flags &= ~PF_BLOCK_TS;
|
| 2343 | #endif
|
| 2344 | futex_init_task(p);
|
| 2345 |
|
| 2346 | |
| 2347 | * sigaltstack should be cleared when sharing the same VM
|
| 2348 |
|
| 2349 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
|
| 2350 | sas_ss_reset(p);
|
| 2351 |
|
| 2352 | |
| 2353 | * Syscall tracing and stepping should be turned off in the
|
| 2354 | * child regardless of CLONE_PTRACE.
|
| 2355 |
|
| 2356 | user_disable_single_step(p);
|
| 2357 | clear_task_syscall_work(p, SYSCALL_TRACE);
|
| 2358 | #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
|
| 2359 | clear_task_syscall_work(p, SYSCALL_EMU);
|
| 2360 | #endif
|
| 2361 | clear_tsk_latency_tracing(p);
|
| 2362 |
|
| 2363 |
|
| 2364 | p->pid = pid_nr(pid);
|
| 2365 | if (clone_flags & CLONE_THREAD) {
|
| 2366 | p->group_leader = current->group_leader;
|
| 2367 | p->tgid = current->tgid;
|
| 2368 | } else {
|
| 2369 | p->group_leader = p;
|
| 2370 | p->tgid = p->pid;
|
| 2371 | }
|
| 2372 |
|
| 2373 | p->nr_dirtied = 0;
|
| 2374 | p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
|
| 2375 | p->dirty_paused_when = 0;
|
| 2376 |
|
| 2377 | p->pdeath_signal = 0;
|
| 2378 | p->task_works = NULL;
|
| 2379 | clear_posix_cputimers_work(p);
|
| 2380 |
|
| 2381 | #ifdef CONFIG_KRETPROBES
|
| 2382 | p->kretprobe_instances.first = NULL;
|
| 2383 | #endif
|
| 2384 | #ifdef CONFIG_RETHOOK
|
| 2385 | p->rethooks.first = NULL;
|
| 2386 | #endif
|
| 2387 |
|
| 2388 | |
| 2389 | * Ensure that the cgroup subsystem policies allow the new process to be
|
| 2390 | * forked. It should be noted that the new process's css_set can be changed
|
| 2391 | * between here and cgroup_post_fork() if an organisation operation is in
|
| 2392 | * progress.
|
| 2393 |
|
| 2394 | retval = cgroup_can_fork(p, args);
|
| 2395 | if (retval)
|
| 2396 | goto bad_fork_put_pidfd;
|
| 2397 |
|
| 2398 | |
| 2399 | * Now that the cgroups are pinned, re-clone the parent cgroup and put
|
| 2400 | * the new task on the correct runqueue. All this *before* the task
|
| 2401 | * becomes visible.
|
| 2402 | *
|
| 2403 | * This isn't part of ->can_fork() because while the re-cloning is
|
| 2404 | * cgroup specific, it unconditionally needs to place the task on a
|
| 2405 | * runqueue.
|
| 2406 |
|
| 2407 | retval = sched_cgroup_fork(p, args);
|
| 2408 | if (retval)
|
| 2409 | goto bad_fork_cancel_cgroup;
|
| 2410 |
|
| 2411 | if (need_futex_hash_allocate_default(clone_flags)) {
|
| 2412 | retval = futex_hash_allocate_default();
|
| 2413 | if (retval)
|
| 2414 | goto bad_fork_cancel_cgroup;
|
| 2415 | |
| 2416 | * If we fail beyond this point we don't free the allocated
|
| 2417 | * futex hash map. We assume that another thread will be created
|
| 2418 | * and makes use of it. The hash map will be freed once the main
|
| 2419 | * thread terminates.
|
| 2420 |
|
| 2421 | }
|
| 2422 | |
| 2423 | * From this point on we must avoid any synchronous user-space
|
| 2424 | * communication until we take the tasklist-lock. In particular, we do
|
| 2425 | * not want user-space to be able to predict the process start-time by
|
| 2426 | * stalling fork(2) after we recorded the start_time but before it is
|
| 2427 | * visible to the system.
|
| 2428 |
|
| 2429 |
|
| 2430 | p->start_time = ktime_get_ns();
|
| 2431 | p->start_boottime = ktime_get_boottime_ns();
|
| 2432 |
|
| 2433 | |
| 2434 | * Make it visible to the rest of the system, but dont wake it up yet.
|
| 2435 | * Need tasklist lock for parent etc handling!
|
| 2436 |
|
| 2437 | write_lock_irq(&tasklist_lock);
|
| 2438 |
|
| 2439 |
|
| 2440 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
|
| 2441 | p->real_parent = current->real_parent;
|
| 2442 | p->parent_exec_id = current->parent_exec_id;
|
| 2443 | if (clone_flags & CLONE_THREAD)
|
| 2444 | p->exit_signal = -1;
|
| 2445 | else
|
| 2446 | p->exit_signal = current->group_leader->exit_signal;
|
| 2447 | } else {
|
| 2448 | p->real_parent = current;
|
| 2449 | p->parent_exec_id = current->self_exec_id;
|
| 2450 | p->exit_signal = args->exit_signal;
|
| 2451 | }
|
| 2452 |
|
| 2453 | klp_copy_process(p);
|
| 2454 |
|
| 2455 | sched_core_fork(p);
|
| 2456 |
|
| 2457 | spin_lock(¤t->sighand->siglock);
|
| 2458 |
|
| 2459 | rv_task_fork(p);
|
| 2460 |
|
| 2461 | rseq_fork(p, clone_flags);
|
| 2462 |
|
| 2463 | |
| 2464 | * If zap_pid_ns_processes() was called after alloc_pid(), the new
|
| 2465 | * child missed SIGKILL. If current is not in the same namespace,
|
| 2466 | * we can't rely on fatal_signal_pending() below.
|
| 2467 |
|
| 2468 | if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
|
| 2469 | retval = -ENOMEM;
|
| 2470 | goto bad_fork_core_free;
|
| 2471 | }
|
| 2472 |
|
| 2473 |
|
| 2474 | if (fatal_signal_pending(current)) {
|
| 2475 | retval = -EINTR;
|
| 2476 | goto bad_fork_core_free;
|
| 2477 | }
|
| 2478 |
|
| 2479 |
|
| 2480 |
|
| 2481 | |
| 2482 | * Copy seccomp details explicitly here, in case they were changed
|
| 2483 | * before holding sighand lock.
|
| 2484 |
|
| 2485 | copy_seccomp(p);
|
| 2486 |
|
| 2487 | if (clone_flags & CLONE_NNP)
|
| 2488 | task_set_no_new_privs(p);
|
| 2489 |
|
| 2490 | init_task_pid_links(p);
|
| 2491 | if (likely(p->pid)) {
|
| 2492 | ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
|
| 2493 |
|
| 2494 | init_task_pid(p, PIDTYPE_PID, pid);
|
| 2495 | if (thread_group_leader(p)) {
|
| 2496 | init_task_pid(p, PIDTYPE_TGID, pid);
|
| 2497 | init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
|
| 2498 | init_task_pid(p, PIDTYPE_SID, task_session(current));
|
| 2499 |
|
| 2500 | if (is_child_reaper(pid)) {
|
| 2501 | struct pid_namespace *ns = ns_of_pid(pid);
|
| 2502 |
|
| 2503 | ASSERT_EXCLUSIVE_WRITER(ns->child_reaper);
|
| 2504 | WRITE_ONCE(ns->child_reaper, p);
|
| 2505 | p->signal->flags |= SIGNAL_UNKILLABLE;
|
| 2506 | }
|
| 2507 | p->signal->shared_pending.signal = delayed.signal;
|
| 2508 | p->signal->tty = tty_kref_get(current->signal->tty);
|
| 2509 | |
| 2510 | * Inherit has_child_subreaper flag under the same
|
| 2511 | * tasklist_lock with adding child to the process tree
|
| 2512 | * for propagate_has_child_subreaper optimization.
|
| 2513 |
|
| 2514 | p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
|
| 2515 | p->real_parent->signal->is_child_subreaper;
|
| 2516 | if (clone_flags & CLONE_AUTOREAP)
|
| 2517 | p->signal->autoreap = 1;
|
| 2518 | list_add_tail(&p->sibling, &p->real_parent->children);
|
| 2519 | list_add_tail_rcu(&p->tasks, &init_task.tasks);
|
| 2520 | attach_pid(p, PIDTYPE_TGID);
|
| 2521 | attach_pid(p, PIDTYPE_PGID);
|
| 2522 | attach_pid(p, PIDTYPE_SID);
|
| 2523 | __this_cpu_inc(process_counts);
|
| 2524 | } else {
|
| 2525 | current->signal->nr_threads++;
|
| 2526 | current->signal->quick_threads++;
|
| 2527 | atomic_inc(¤t->signal->live);
|
| 2528 | refcount_inc(¤t->signal->sigcnt);
|
| 2529 | task_join_group_stop(p);
|
| 2530 | list_add_tail_rcu(&p->thread_node,
|
| 2531 | &p->signal->thread_head);
|
| 2532 | }
|
| 2533 | attach_pid(p, PIDTYPE_PID);
|
| 2534 | nr_threads++;
|
| 2535 | }
|
| 2536 | total_forks++;
|
| 2537 | hlist_del_init(&delayed.node);
|
| 2538 | spin_unlock(¤t->sighand->siglock);
|
| 2539 | syscall_tracepoint_update(p);
|
| 2540 | write_unlock_irq(&tasklist_lock);
|
| 2541 |
|
| 2542 | if (pidfile)
|
| 2543 | fd_install(pidfd, pidfile);
|
| 2544 |
|
| 2545 | proc_fork_connector(p);
|
| 2546 | |
| 2547 | * sched_ext needs @p to be associated with its cgroup in its post_fork
|
| 2548 | * hook. cgroup_post_fork() should come before sched_post_fork().
|
| 2549 |
|
| 2550 | cgroup_post_fork(p, args);
|
| 2551 | sched_post_fork(p);
|
| 2552 | perf_event_fork(p);
|
| 2553 |
|
| 2554 | trace_task_newtask(p, clone_flags);
|
| 2555 | uprobe_copy_process(p, clone_flags);
|
| 2556 | user_events_fork(p, clone_flags);
|
| 2557 |
|
| 2558 | copy_oom_score_adj(clone_flags, p);
|
| 2559 |
|
| 2560 | return p;
|
| 2561 |
|
| 2562 | bad_fork_core_free:
|
| 2563 | sched_core_free(p);
|
| 2564 | spin_unlock(¤t->sighand->siglock);
|
| 2565 | write_unlock_irq(&tasklist_lock);
|
| 2566 | bad_fork_cancel_cgroup:
|
| 2567 | cgroup_cancel_fork(p, args);
|
| 2568 | bad_fork_put_pidfd:
|
| 2569 | if (clone_flags & CLONE_PIDFD) {
|
| 2570 | fput(pidfile);
|
| 2571 | put_unused_fd(pidfd);
|
| 2572 | }
|
| 2573 | bad_fork_free_pid:
|
| 2574 | if (pid != &init_struct_pid)
|
| 2575 | free_pid(pid);
|
| 2576 | bad_fork_cleanup_thread:
|
| 2577 | exit_thread(p);
|
| 2578 | bad_fork_cleanup_io:
|
| 2579 | if (p->io_context)
|
| 2580 | exit_io_context(p);
|
| 2581 | bad_fork_cleanup_namespaces:
|
| 2582 | exit_nsproxy_namespaces(p);
|
| 2583 | bad_fork_cleanup_mm:
|
| 2584 | if (p->mm) {
|
| 2585 | mm_clear_owner(p->mm, p);
|
| 2586 | mmput(p->mm);
|
| 2587 | }
|
| 2588 | bad_fork_cleanup_signal:
|
| 2589 | if (!(clone_flags & CLONE_THREAD))
|
| 2590 | free_signal_struct(p->signal);
|
| 2591 | bad_fork_cleanup_sighand:
|
| 2592 | __cleanup_sighand(p->sighand);
|
| 2593 | bad_fork_cleanup_fs:
|
| 2594 | exit_fs(p);
|
| 2595 | bad_fork_cleanup_files:
|
| 2596 | exit_files(p);
|
| 2597 | bad_fork_cleanup_semundo:
|
| 2598 | exit_sem(p);
|
| 2599 | bad_fork_cleanup_security:
|
| 2600 | security_task_free(p);
|
| 2601 | bad_fork_cleanup_audit:
|
| 2602 | audit_free(p);
|
| 2603 | bad_fork_cleanup_perf:
|
| 2604 | perf_event_free_task(p);
|
| 2605 | bad_fork_sched_cancel_fork:
|
| 2606 | sched_cancel_fork(p);
|
| 2607 | bad_fork_cleanup_policy:
|
| 2608 | lockdep_free_task(p);
|
| 2609 | #ifdef CONFIG_NUMA
|
| 2610 | mpol_put(p->mempolicy);
|
| 2611 | #endif
|
| 2612 | bad_fork_cleanup_delayacct:
|
| 2613 | io_uring_free(p);
|
| 2614 | delayacct_tsk_free(p);
|
| 2615 | bad_fork_cleanup_count:
|
| 2616 | dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
|
| 2617 | exit_cred_namespaces(p);
|
| 2618 | exit_creds(p);
|
| 2619 | bad_fork_free:
|
| 2620 | WRITE_ONCE(p->__state, TASK_DEAD);
|
| 2621 | exit_task_stack_account(p);
|
| 2622 | put_task_stack(p);
|
| 2623 | delayed_free_task(p);
|
| 2624 | fork_out:
|
| 2625 | spin_lock_irq(¤t->sighand->siglock);
|
| 2626 | hlist_del_init(&delayed.node);
|
| 2627 | spin_unlock_irq(¤t->sighand->siglock);
|
| 2628 | return ERR_PTR(retval);
|
| 2629 | }
|
| 2630 |
|
| 2631 | static inline void init_idle_pids(struct task_struct *idle)
|
| 2632 | {
|
| 2633 | enum pid_type type;
|
| 2634 |
|
| 2635 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
|
| 2636 | INIT_HLIST_NODE(&idle->pid_links[type]);
|
| 2637 | init_task_pid(idle, type, &init_struct_pid);
|
| 2638 | }
|
| 2639 | }
|
| 2640 |
|
| 2641 | static int idle_dummy(void *dummy)
|
| 2642 | {
|
| 2643 |
|
| 2644 | return 0;
|
| 2645 | }
|
| 2646 |
|
| 2647 | struct task_struct * __init fork_idle(int cpu)
|
| 2648 | {
|
| 2649 | struct task_struct *task;
|
| 2650 | struct kernel_clone_args args = {
|
| 2651 | .flags = CLONE_VM,
|
| 2652 | .fn = &idle_dummy,
|
| 2653 | .fn_arg = NULL,
|
| 2654 | .kthread = 1,
|
| 2655 | .idle = 1,
|
| 2656 | };
|
| 2657 |
|
| 2658 | task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
|
| 2659 | if (!IS_ERR(task)) {
|
| 2660 | init_idle_pids(task);
|
| 2661 | init_idle(task, cpu);
|
| 2662 | }
|
| 2663 |
|
| 2664 | return task;
|
| 2665 | }
|
| 2666 |
|
| 2667 | |
| 2668 | * This is like kernel_clone(), but shaved down and tailored to just
|
| 2669 | * creating io_uring workers. It returns a created task, or an error pointer.
|
| 2670 | * The returned task is inactive, and the caller must fire it up through
|
| 2671 | * wake_up_new_task(p). All signals are blocked in the created task.
|
| 2672 |
|
| 2673 | struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
|
| 2674 | {
|
| 2675 | unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
|
| 2676 | CLONE_IO|CLONE_VM|CLONE_UNTRACED;
|
| 2677 | struct kernel_clone_args args = {
|
| 2678 | .flags = flags,
|
| 2679 | .fn = fn,
|
| 2680 | .fn_arg = arg,
|
| 2681 | .io_thread = 1,
|
| 2682 | .user_worker = 1,
|
| 2683 | };
|
| 2684 |
|
| 2685 | return copy_process(NULL, 0, node, &args);
|
| 2686 | }
|
| 2687 |
|
| 2688 | |
| 2689 | * Ok, this is the main fork-routine.
|
| 2690 | *
|
| 2691 | * It copies the process, and if successful kick-starts
|
| 2692 | * it and waits for it to finish using the VM if required.
|
| 2693 |
|
| 2694 | pid_t kernel_clone(struct kernel_clone_args *args)
|
| 2695 | {
|
| 2696 | u64 clone_flags = args->flags;
|
| 2697 | struct completion vfork;
|
| 2698 | struct pid *pid;
|
| 2699 | struct task_struct *p;
|
| 2700 | int trace = 0;
|
| 2701 | pid_t nr;
|
| 2702 |
|
| 2703 | |
| 2704 | * Creating an empty mount namespace implies creating a new mount
|
| 2705 | * namespace. Set this before copy_process() so that the
|
| 2706 | * CLONE_NEWNS|CLONE_FS mutual exclusion check works correctly.
|
| 2707 |
|
| 2708 | if (clone_flags & CLONE_EMPTY_MNTNS) {
|
| 2709 | clone_flags |= CLONE_NEWNS;
|
| 2710 | args->flags = clone_flags;
|
| 2711 | }
|
| 2712 |
|
| 2713 | |
| 2714 | * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
|
| 2715 | * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
|
| 2716 | * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
|
| 2717 | * field in struct clone_args and it still doesn't make sense to have
|
| 2718 | * them both point at the same memory location. Performing this check
|
| 2719 | * here has the advantage that we don't need to have a separate helper
|
| 2720 | * to check for legacy clone().
|
| 2721 |
|
| 2722 | if ((clone_flags & CLONE_PIDFD) &&
|
| 2723 | (clone_flags & CLONE_PARENT_SETTID) &&
|
| 2724 | (args->pidfd == args->parent_tid))
|
| 2725 | return -EINVAL;
|
| 2726 |
|
| 2727 | if (!valid_signal(args->exit_signal))
|
| 2728 | return -EINVAL;
|
| 2729 |
|
| 2730 | |
| 2731 | * Determine whether and which event to report to ptracer. When
|
| 2732 | * called from kernel_thread or CLONE_UNTRACED is explicitly
|
| 2733 | * requested, no event is reported; otherwise, report if the event
|
| 2734 | * for the type of forking is enabled.
|
| 2735 |
|
| 2736 | if (!(clone_flags & CLONE_UNTRACED)) {
|
| 2737 | if (clone_flags & CLONE_VFORK)
|
| 2738 | trace = PTRACE_EVENT_VFORK;
|
| 2739 | else if (args->exit_signal != SIGCHLD)
|
| 2740 | trace = PTRACE_EVENT_CLONE;
|
| 2741 | else
|
| 2742 | trace = PTRACE_EVENT_FORK;
|
| 2743 |
|
| 2744 | if (likely(!ptrace_event_enabled(current, trace)))
|
| 2745 | trace = 0;
|
| 2746 | }
|
| 2747 |
|
| 2748 | p = copy_process(NULL, trace, NUMA_NO_NODE, args);
|
| 2749 | add_latent_entropy();
|
| 2750 |
|
| 2751 | if (IS_ERR(p))
|
| 2752 | return PTR_ERR(p);
|
| 2753 |
|
| 2754 | |
| 2755 | * Do this prior waking up the new thread - the thread pointer
|
| 2756 | * might get invalid after that point, if the thread exits quickly.
|
| 2757 |
|
| 2758 | trace_sched_process_fork(current, p);
|
| 2759 |
|
| 2760 | pid = get_task_pid(p, PIDTYPE_PID);
|
| 2761 | nr = pid_vnr(pid);
|
| 2762 |
|
| 2763 | if (clone_flags & CLONE_PARENT_SETTID)
|
| 2764 | put_user(nr, args->parent_tid);
|
| 2765 |
|
| 2766 | if (clone_flags & CLONE_VFORK) {
|
| 2767 | p->vfork_done = &vfork;
|
| 2768 | init_completion(&vfork);
|
| 2769 | get_task_struct(p);
|
| 2770 | }
|
| 2771 |
|
| 2772 | if (IS_ENABLED(CONFIG_LRU_GEN_WALKS_MMU) && !(clone_flags & CLONE_VM)) {
|
| 2773 |
|
| 2774 | task_lock(p);
|
| 2775 | lru_gen_add_mm(p->mm);
|
| 2776 | task_unlock(p);
|
| 2777 | }
|
| 2778 |
|
| 2779 | wake_up_new_task(p);
|
| 2780 |
|
| 2781 |
|
| 2782 | if (unlikely(trace))
|
| 2783 | ptrace_event_pid(trace, pid);
|
| 2784 |
|
| 2785 | if (clone_flags & CLONE_VFORK) {
|
| 2786 | if (!wait_for_vfork_done(p, &vfork))
|
| 2787 | ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
|
| 2788 | }
|
| 2789 |
|
| 2790 | put_pid(pid);
|
| 2791 | return nr;
|
| 2792 | }
|
| 2793 |
|
| 2794 | |
| 2795 | * Create a kernel thread.
|
| 2796 |
|
| 2797 | pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
|
| 2798 | unsigned long flags)
|
| 2799 | {
|
| 2800 | struct kernel_clone_args args = {
|
| 2801 | .flags = ((flags | CLONE_VM | CLONE_UNTRACED) & ~CSIGNAL),
|
| 2802 | .exit_signal = (flags & CSIGNAL),
|
| 2803 | .fn = fn,
|
| 2804 | .fn_arg = arg,
|
| 2805 | .name = name,
|
| 2806 | .kthread = 1,
|
| 2807 | };
|
| 2808 |
|
| 2809 | return kernel_clone(&args);
|
| 2810 | }
|
| 2811 |
|
| 2812 | |
| 2813 | * Create a user mode thread.
|
| 2814 |
|
| 2815 | pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
|
| 2816 | {
|
| 2817 | struct kernel_clone_args args = {
|
| 2818 | .flags = ((flags | CLONE_VM | CLONE_UNTRACED) & ~CSIGNAL),
|
| 2819 | .exit_signal = (flags & CSIGNAL),
|
| 2820 | .fn = fn,
|
| 2821 | .fn_arg = arg,
|
| 2822 | };
|
| 2823 |
|
| 2824 | return kernel_clone(&args);
|
| 2825 | }
|
| 2826 |
|
| 2827 | #ifdef __ARCH_WANT_SYS_FORK
|
| 2828 | SYSCALL_DEFINE0(fork)
|
| 2829 | {
|
| 2830 | #ifdef CONFIG_MMU
|
| 2831 | struct kernel_clone_args args = {
|
| 2832 | .exit_signal = SIGCHLD,
|
| 2833 | };
|
| 2834 |
|
| 2835 | return kernel_clone(&args);
|
| 2836 | #else
|
| 2837 |
|
| 2838 | return -EINVAL;
|
| 2839 | #endif
|
| 2840 | }
|
| 2841 | #endif
|
| 2842 |
|
| 2843 | #ifdef __ARCH_WANT_SYS_VFORK
|
| 2844 | SYSCALL_DEFINE0(vfork)
|
| 2845 | {
|
| 2846 | struct kernel_clone_args args = {
|
| 2847 | .flags = CLONE_VFORK | CLONE_VM,
|
| 2848 | .exit_signal = SIGCHLD,
|
| 2849 | };
|
| 2850 |
|
| 2851 | return kernel_clone(&args);
|
| 2852 | }
|
| 2853 | #endif
|
| 2854 |
|
| 2855 | #ifdef __ARCH_WANT_SYS_CLONE
|
| 2856 | #ifdef CONFIG_CLONE_BACKWARDS
|
| 2857 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
|
| 2858 | int __user *, parent_tidptr,
|
| 2859 | unsigned long, tls,
|
| 2860 | int __user *, child_tidptr)
|
| 2861 | #elif defined(CONFIG_CLONE_BACKWARDS2)
|
| 2862 | SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
|
| 2863 | int __user *, parent_tidptr,
|
| 2864 | int __user *, child_tidptr,
|
| 2865 | unsigned long, tls)
|
| 2866 | #elif defined(CONFIG_CLONE_BACKWARDS3)
|
| 2867 | SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
|
| 2868 | int, stack_size,
|
| 2869 | int __user *, parent_tidptr,
|
| 2870 | int __user *, child_tidptr,
|
| 2871 | unsigned long, tls)
|
| 2872 | #else
|
| 2873 | SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
|
| 2874 | int __user *, parent_tidptr,
|
| 2875 | int __user *, child_tidptr,
|
| 2876 | unsigned long, tls)
|
| 2877 | #endif
|
| 2878 | {
|
| 2879 | struct kernel_clone_args args = {
|
| 2880 | .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
|
| 2881 | .pidfd = parent_tidptr,
|
| 2882 | .child_tid = child_tidptr,
|
| 2883 | .parent_tid = parent_tidptr,
|
| 2884 | .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
|
| 2885 | .stack = newsp,
|
| 2886 | .tls = tls,
|
| 2887 | };
|
| 2888 |
|
| 2889 | return kernel_clone(&args);
|
| 2890 | }
|
| 2891 | #endif
|
| 2892 |
|
| 2893 | static noinline int copy_clone_args_from_user(struct kernel_clone_args *kargs,
|
| 2894 | struct clone_args __user *uargs,
|
| 2895 | size_t usize)
|
| 2896 | {
|
| 2897 | int err;
|
| 2898 | struct clone_args args;
|
| 2899 | pid_t *kset_tid = kargs->set_tid;
|
| 2900 |
|
| 2901 | BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
|
| 2902 | CLONE_ARGS_SIZE_VER0);
|
| 2903 | BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
|
| 2904 | CLONE_ARGS_SIZE_VER1);
|
| 2905 | BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
|
| 2906 | CLONE_ARGS_SIZE_VER2);
|
| 2907 | BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
|
| 2908 |
|
| 2909 | if (unlikely(usize > PAGE_SIZE))
|
| 2910 | return -E2BIG;
|
| 2911 | if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
|
| 2912 | return -EINVAL;
|
| 2913 |
|
| 2914 | err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
|
| 2915 | if (err)
|
| 2916 | return err;
|
| 2917 |
|
| 2918 | if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
|
| 2919 | return -EINVAL;
|
| 2920 |
|
| 2921 | if (unlikely(!args.set_tid && args.set_tid_size > 0))
|
| 2922 | return -EINVAL;
|
| 2923 |
|
| 2924 | if (unlikely(args.set_tid && args.set_tid_size == 0))
|
| 2925 | return -EINVAL;
|
| 2926 |
|
| 2927 | |
| 2928 | * Verify that higher 32bits of exit_signal are unset
|
| 2929 |
|
| 2930 | if (unlikely(args.exit_signal & ~((u64)CSIGNAL)))
|
| 2931 | return -EINVAL;
|
| 2932 |
|
| 2933 | if ((args.flags & CLONE_INTO_CGROUP) &&
|
| 2934 | (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
|
| 2935 | return -EINVAL;
|
| 2936 |
|
| 2937 | *kargs = (struct kernel_clone_args){
|
| 2938 | .flags = args.flags,
|
| 2939 | .pidfd = u64_to_user_ptr(args.pidfd),
|
| 2940 | .child_tid = u64_to_user_ptr(args.child_tid),
|
| 2941 | .parent_tid = u64_to_user_ptr(args.parent_tid),
|
| 2942 | .exit_signal = args.exit_signal,
|
| 2943 | .stack = args.stack,
|
| 2944 | .stack_size = args.stack_size,
|
| 2945 | .tls = args.tls,
|
| 2946 | .set_tid_size = args.set_tid_size,
|
| 2947 | .cgroup = args.cgroup,
|
| 2948 | };
|
| 2949 |
|
| 2950 | if (args.set_tid &&
|
| 2951 | copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
|
| 2952 | (kargs->set_tid_size * sizeof(pid_t))))
|
| 2953 | return -EFAULT;
|
| 2954 |
|
| 2955 | kargs->set_tid = kset_tid;
|
| 2956 |
|
| 2957 | return 0;
|
| 2958 | }
|
| 2959 |
|
| 2960 | |
| 2961 | * clone3_stack_valid - check and prepare stack
|
| 2962 | * @kargs: kernel clone args
|
| 2963 | *
|
| 2964 | * Verify that the stack arguments userspace gave us are sane.
|
| 2965 | * In addition, set the stack direction for userspace since it's easy for us to
|
| 2966 | * determine.
|
| 2967 |
|
| 2968 | static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
|
| 2969 | {
|
| 2970 | if (kargs->stack == 0) {
|
| 2971 | if (kargs->stack_size > 0)
|
| 2972 | return false;
|
| 2973 | } else {
|
| 2974 | if (kargs->stack_size == 0)
|
| 2975 | return false;
|
| 2976 |
|
| 2977 | if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
|
| 2978 | return false;
|
| 2979 |
|
| 2980 | #if !defined(CONFIG_STACK_GROWSUP)
|
| 2981 | kargs->stack += kargs->stack_size;
|
| 2982 | #endif
|
| 2983 | }
|
| 2984 |
|
| 2985 | return true;
|
| 2986 | }
|
| 2987 |
|
| 2988 | static bool clone3_args_valid(struct kernel_clone_args *kargs)
|
| 2989 | {
|
| 2990 |
|
| 2991 | if (kargs->flags &
|
| 2992 | ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND |
|
| 2993 | CLONE_INTO_CGROUP | CLONE_AUTOREAP | CLONE_NNP |
|
| 2994 | CLONE_PIDFD_AUTOKILL | CLONE_EMPTY_MNTNS))
|
| 2995 | return false;
|
| 2996 |
|
| 2997 | |
| 2998 | * - make the CLONE_DETACHED bit reusable for clone3
|
| 2999 | * - make the CSIGNAL bits reusable for clone3
|
| 3000 |
|
| 3001 | if (kargs->flags & (CLONE_DETACHED | (CSIGNAL & (~CLONE_NEWTIME))))
|
| 3002 | return false;
|
| 3003 |
|
| 3004 | if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
|
| 3005 | (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
|
| 3006 | return false;
|
| 3007 |
|
| 3008 | if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
|
| 3009 | kargs->exit_signal)
|
| 3010 | return false;
|
| 3011 |
|
| 3012 | if (!clone3_stack_valid(kargs))
|
| 3013 | return false;
|
| 3014 |
|
| 3015 | return true;
|
| 3016 | }
|
| 3017 |
|
| 3018 | |
| 3019 | * sys_clone3 - create a new process with specific properties
|
| 3020 | * @uargs: argument structure
|
| 3021 | * @size: size of @uargs
|
| 3022 | *
|
| 3023 | * clone3() is the extensible successor to clone()/clone2().
|
| 3024 | * It takes a struct as argument that is versioned by its size.
|
| 3025 | *
|
| 3026 | * Return: On success, a positive PID for the child process.
|
| 3027 | * On error, a negative errno number.
|
| 3028 |
|
| 3029 | SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
|
| 3030 | {
|
| 3031 | int err;
|
| 3032 |
|
| 3033 | struct kernel_clone_args kargs;
|
| 3034 | pid_t set_tid[MAX_PID_NS_LEVEL];
|
| 3035 |
|
| 3036 | #ifdef __ARCH_BROKEN_SYS_CLONE3
|
| 3037 | #warning clone3() entry point is missing, please fix
|
| 3038 | return -ENOSYS;
|
| 3039 | #endif
|
| 3040 |
|
| 3041 | kargs.set_tid = set_tid;
|
| 3042 |
|
| 3043 | err = copy_clone_args_from_user(&kargs, uargs, size);
|
| 3044 | if (err)
|
| 3045 | return err;
|
| 3046 |
|
| 3047 | if (!clone3_args_valid(&kargs))
|
| 3048 | return -EINVAL;
|
| 3049 |
|
| 3050 | return kernel_clone(&kargs);
|
| 3051 | }
|
| 3052 |
|
| 3053 | void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
|
| 3054 | {
|
| 3055 | struct task_struct *leader, *parent, *child;
|
| 3056 | int res;
|
| 3057 |
|
| 3058 | read_lock(&tasklist_lock);
|
| 3059 | leader = top = top->group_leader;
|
| 3060 | down:
|
| 3061 | for_each_thread(leader, parent) {
|
| 3062 | list_for_each_entry(child, &parent->children, sibling) {
|
| 3063 | res = visitor(child, data);
|
| 3064 | if (res) {
|
| 3065 | if (res < 0)
|
| 3066 | goto out;
|
| 3067 | leader = child;
|
| 3068 | goto down;
|
| 3069 | }
|
| 3070 | up:
|
| 3071 | ;
|
| 3072 | }
|
| 3073 | }
|
| 3074 |
|
| 3075 | if (leader != top) {
|
| 3076 | child = leader;
|
| 3077 | parent = child->real_parent;
|
| 3078 | leader = parent->group_leader;
|
| 3079 | goto up;
|
| 3080 | }
|
| 3081 | out:
|
| 3082 | read_unlock(&tasklist_lock);
|
| 3083 | }
|
| 3084 |
|
| 3085 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN
|
| 3086 | #define ARCH_MIN_MMSTRUCT_ALIGN 0
|
| 3087 | #endif
|
| 3088 |
|
| 3089 | static void sighand_ctor(void *data)
|
| 3090 | {
|
| 3091 | struct sighand_struct *sighand = data;
|
| 3092 |
|
| 3093 | spin_lock_init(&sighand->siglock);
|
| 3094 | init_waitqueue_head(&sighand->signalfd_wqh);
|
| 3095 | }
|
| 3096 |
|
| 3097 | void __init mm_cache_init(void)
|
| 3098 | {
|
| 3099 | unsigned int mm_size;
|
| 3100 |
|
| 3101 | |
| 3102 | * The mm_cpumask is located at the end of mm_struct, and is
|
| 3103 | * dynamically sized based on the maximum CPU number this system
|
| 3104 | * can have, taking hotplug into account (nr_cpu_ids).
|
| 3105 |
|
| 3106 | mm_size = sizeof(struct mm_struct) + cpumask_size() + mm_cid_size();
|
| 3107 |
|
| 3108 | mm_cachep = kmem_cache_create_usercopy("mm_struct",
|
| 3109 | mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
|
| 3110 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
| 3111 | offsetof(struct mm_struct, saved_auxv),
|
| 3112 | sizeof_field(struct mm_struct, saved_auxv),
|
| 3113 | NULL);
|
| 3114 | }
|
| 3115 |
|
| 3116 | void __init proc_caches_init(void)
|
| 3117 | {
|
| 3118 | sighand_cachep = kmem_cache_create("sighand_cache",
|
| 3119 | sizeof(struct sighand_struct), 0,
|
| 3120 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
|
| 3121 | SLAB_ACCOUNT, sighand_ctor);
|
| 3122 | signal_cachep = kmem_cache_create("signal_cache",
|
| 3123 | sizeof(struct signal_struct), 0,
|
| 3124 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
| 3125 | NULL);
|
| 3126 | exec_state_init();
|
| 3127 | files_cachep = kmem_cache_create("files_cache",
|
| 3128 | sizeof(struct files_struct), 0,
|
| 3129 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
| 3130 | NULL);
|
| 3131 | fs_cachep = kmem_cache_create("fs_cache",
|
| 3132 | sizeof(struct fs_struct), 0,
|
| 3133 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
| 3134 | NULL);
|
| 3135 | mmap_init();
|
| 3136 | nsproxy_cache_init();
|
| 3137 | }
|
| 3138 |
|
| 3139 | |
| 3140 | * Check constraints on flags passed to the unshare system call.
|
| 3141 |
|
| 3142 | static int check_unshare_flags(unsigned long unshare_flags)
|
| 3143 | {
|
| 3144 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_SIGHAND|
|
| 3145 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
|
| 3146 | CLONE_NS_ALL | UNSHARE_EMPTY_MNTNS))
|
| 3147 | return -EINVAL;
|
| 3148 | |
| 3149 | * Not implemented, but pretend it works if there is nothing
|
| 3150 | * to unshare. Note that unsharing the address space or the
|
| 3151 | * signal handlers also need to unshare the signal queues (aka
|
| 3152 | * CLONE_THREAD).
|
| 3153 |
|
| 3154 | if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
|
| 3155 | if (!thread_group_empty(current))
|
| 3156 | return -EINVAL;
|
| 3157 | }
|
| 3158 | if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
|
| 3159 | if (refcount_read(¤t->sighand->count) > 1)
|
| 3160 | return -EINVAL;
|
| 3161 | }
|
| 3162 | if (unshare_flags & CLONE_VM) {
|
| 3163 | if (!current_is_single_threaded())
|
| 3164 | return -EINVAL;
|
| 3165 | }
|
| 3166 |
|
| 3167 | return 0;
|
| 3168 | }
|
| 3169 |
|
| 3170 | |
| 3171 | * Unshare the filesystem structure if it is being shared
|
| 3172 |
|
| 3173 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
|
| 3174 | {
|
| 3175 | struct fs_struct *fs = current->fs;
|
| 3176 |
|
| 3177 | if (!(unshare_flags & CLONE_FS) || !fs)
|
| 3178 | return 0;
|
| 3179 |
|
| 3180 |
|
| 3181 | if (!(unshare_flags & CLONE_NEWNS) && fs->users == 1)
|
| 3182 | return 0;
|
| 3183 |
|
| 3184 | *new_fsp = copy_fs_struct(fs);
|
| 3185 | if (!*new_fsp)
|
| 3186 | return -ENOMEM;
|
| 3187 |
|
| 3188 | return 0;
|
| 3189 | }
|
| 3190 |
|
| 3191 | |
| 3192 | * Unshare file descriptor table if it is being shared
|
| 3193 |
|
| 3194 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
|
| 3195 | {
|
| 3196 | struct files_struct *fd = current->files;
|
| 3197 |
|
| 3198 | if ((unshare_flags & CLONE_FILES) &&
|
| 3199 | (fd && atomic_read(&fd->count) > 1)) {
|
| 3200 | fd = dup_fd(fd, NULL);
|
| 3201 | if (IS_ERR(fd))
|
| 3202 | return PTR_ERR(fd);
|
| 3203 | *new_fdp = fd;
|
| 3204 | }
|
| 3205 |
|
| 3206 | return 0;
|
| 3207 | }
|
| 3208 |
|
| 3209 | |
| 3210 | * unshare allows a process to 'unshare' part of the process
|
| 3211 | * context which was originally shared using clone. copy_*
|
| 3212 | * functions used by kernel_clone() cannot be used here directly
|
| 3213 | * because they modify an inactive task_struct that is being
|
| 3214 | * constructed. Here we are modifying the current, active,
|
| 3215 | * task_struct.
|
| 3216 |
|
| 3217 | int ksys_unshare(unsigned long unshare_flags)
|
| 3218 | {
|
| 3219 | struct fs_struct *fs, *new_fs = NULL;
|
| 3220 | struct files_struct *new_fd = NULL;
|
| 3221 | struct cred *new_cred = NULL;
|
| 3222 | struct nsproxy *new_nsproxy = NULL;
|
| 3223 | int do_sysvsem = 0;
|
| 3224 | int err;
|
| 3225 |
|
| 3226 | |
| 3227 | * If unsharing a user namespace must also unshare the thread group
|
| 3228 | * and unshare the filesystem root and working directories.
|
| 3229 |
|
| 3230 | if (unshare_flags & CLONE_NEWUSER)
|
| 3231 | unshare_flags |= CLONE_THREAD | CLONE_FS;
|
| 3232 | |
| 3233 | * If unsharing vm, must also unshare signal handlers.
|
| 3234 |
|
| 3235 | if (unshare_flags & CLONE_VM)
|
| 3236 | unshare_flags |= CLONE_SIGHAND;
|
| 3237 | |
| 3238 | * If unsharing a signal handlers, must also unshare the signal queues.
|
| 3239 |
|
| 3240 | if (unshare_flags & CLONE_SIGHAND)
|
| 3241 | unshare_flags |= CLONE_THREAD;
|
| 3242 | |
| 3243 | * If unsharing namespace, must also unshare filesystem information.
|
| 3244 |
|
| 3245 | if (unshare_flags & UNSHARE_EMPTY_MNTNS)
|
| 3246 | unshare_flags |= CLONE_NEWNS;
|
| 3247 | if (unshare_flags & CLONE_NEWNS)
|
| 3248 | unshare_flags |= CLONE_FS;
|
| 3249 |
|
| 3250 | err = check_unshare_flags(unshare_flags);
|
| 3251 | if (err)
|
| 3252 | goto bad_unshare_out;
|
| 3253 | |
| 3254 | * CLONE_NEWIPC must also detach from the undolist: after switching
|
| 3255 | * to a new ipc namespace, the semaphore arrays from the old
|
| 3256 | * namespace are unreachable.
|
| 3257 |
|
| 3258 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
|
| 3259 | do_sysvsem = 1;
|
| 3260 | err = unshare_fs(unshare_flags, &new_fs);
|
| 3261 | if (err)
|
| 3262 | goto bad_unshare_out;
|
| 3263 | err = unshare_fd(unshare_flags, &new_fd);
|
| 3264 | if (err)
|
| 3265 | goto bad_unshare_cleanup_fs;
|
| 3266 | err = unshare_userns(unshare_flags, &new_cred);
|
| 3267 | if (err)
|
| 3268 | goto bad_unshare_cleanup_fd;
|
| 3269 | err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
|
| 3270 | new_cred, new_fs);
|
| 3271 | if (err)
|
| 3272 | goto bad_unshare_cleanup_cred;
|
| 3273 | if (new_cred) {
|
| 3274 | err = set_cred_ucounts(new_cred);
|
| 3275 | if (err)
|
| 3276 | goto bad_unshare_cleanup_nsproxy;
|
| 3277 | }
|
| 3278 |
|
| 3279 | if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
|
| 3280 | if (do_sysvsem) {
|
| 3281 | |
| 3282 | * CLONE_SYSVSEM is equivalent to sys_exit().
|
| 3283 |
|
| 3284 | exit_sem(current);
|
| 3285 | }
|
| 3286 | if (unshare_flags & CLONE_NEWIPC) {
|
| 3287 |
|
| 3288 | exit_shm(current);
|
| 3289 | shm_init_task(current);
|
| 3290 | }
|
| 3291 |
|
| 3292 | if (new_nsproxy) {
|
| 3293 | switch_task_namespaces(current, new_nsproxy);
|
| 3294 | new_nsproxy = NULL;
|
| 3295 | }
|
| 3296 |
|
| 3297 | task_lock(current);
|
| 3298 |
|
| 3299 | if (new_fs) {
|
| 3300 | fs = current->fs;
|
| 3301 | read_seqlock_excl(&fs->seq);
|
| 3302 | current->fs = new_fs;
|
| 3303 | if (--fs->users)
|
| 3304 | new_fs = NULL;
|
| 3305 | else
|
| 3306 | new_fs = fs;
|
| 3307 | read_sequnlock_excl(&fs->seq);
|
| 3308 | }
|
| 3309 |
|
| 3310 | if (new_fd)
|
| 3311 | swap(current->files, new_fd);
|
| 3312 |
|
| 3313 | task_unlock(current);
|
| 3314 |
|
| 3315 | if (new_cred) {
|
| 3316 |
|
| 3317 | commit_creds(new_cred);
|
| 3318 | new_cred = NULL;
|
| 3319 | }
|
| 3320 | }
|
| 3321 |
|
| 3322 | perf_event_namespaces(current);
|
| 3323 |
|
| 3324 | bad_unshare_cleanup_nsproxy:
|
| 3325 | if (new_nsproxy)
|
| 3326 | put_nsproxy(new_nsproxy);
|
| 3327 | bad_unshare_cleanup_cred:
|
| 3328 | if (new_cred)
|
| 3329 | put_cred(new_cred);
|
| 3330 | bad_unshare_cleanup_fd:
|
| 3331 | if (new_fd)
|
| 3332 | put_files_struct(new_fd);
|
| 3333 | bad_unshare_cleanup_fs:
|
| 3334 | if (new_fs)
|
| 3335 | free_fs_struct(new_fs);
|
| 3336 |
|
| 3337 | bad_unshare_out:
|
| 3338 | return err;
|
| 3339 | }
|
| 3340 |
|
| 3341 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
|
| 3342 | {
|
| 3343 | return ksys_unshare(unshare_flags);
|
| 3344 | }
|
| 3345 |
|
| 3346 | |
| 3347 | * Helper to unshare the files of the current task.
|
| 3348 | * We don't want to expose copy_files internals to
|
| 3349 | * the exec layer of the kernel.
|
| 3350 |
|
| 3351 |
|
| 3352 | int unshare_files(void)
|
| 3353 | {
|
| 3354 | struct task_struct *task = current;
|
| 3355 | struct files_struct *old, *copy = NULL;
|
| 3356 | int error;
|
| 3357 |
|
| 3358 | error = unshare_fd(CLONE_FILES, ©);
|
| 3359 | if (error || !copy)
|
| 3360 | return error;
|
| 3361 |
|
| 3362 | old = task->files;
|
| 3363 | task_lock(task);
|
| 3364 | task->files = copy;
|
| 3365 | task_unlock(task);
|
| 3366 | put_files_struct(old);
|
| 3367 | return 0;
|
| 3368 | }
|
| 3369 |
|
| 3370 | static int sysctl_max_threads(const struct ctl_table *table, int write,
|
| 3371 | void *buffer, size_t *lenp, loff_t *ppos)
|
| 3372 | {
|
| 3373 | struct ctl_table t;
|
| 3374 | int ret;
|
| 3375 | int threads = max_threads;
|
| 3376 | int min = 1;
|
| 3377 | int max = MAX_THREADS;
|
| 3378 |
|
| 3379 | t = *table;
|
| 3380 | t.data = &threads;
|
| 3381 | t.extra1 = &min;
|
| 3382 | t.extra2 = &max;
|
| 3383 |
|
| 3384 | ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
|
| 3385 | if (ret || !write)
|
| 3386 | return ret;
|
| 3387 |
|
| 3388 | max_threads = threads;
|
| 3389 |
|
| 3390 | return 0;
|
| 3391 | }
|
| 3392 |
|
| 3393 | static const struct ctl_table fork_sysctl_table[] = {
|
| 3394 | {
|
| 3395 | .procname = "threads-max",
|
| 3396 | .data = NULL,
|
| 3397 | .maxlen = sizeof(int),
|
| 3398 | .mode = 0644,
|
| 3399 | .proc_handler = sysctl_max_threads,
|
| 3400 | },
|
| 3401 | };
|
| 3402 |
|
| 3403 | static int __init init_fork_sysctl(void)
|
| 3404 | {
|
| 3405 | register_sysctl_init("kernel", fork_sysctl_table);
|
| 3406 | return 0;
|
| 3407 | }
|
| 3408 |
|
| 3409 | subsys_initcall(init_fork_sysctl);
|