| 1 |
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| 2 | |
| 3 | * descriptor table internals; you almost certainly want file.h instead.
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| 4 |
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| 5 |
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| 6 | #ifndef __LINUX_FDTABLE_H
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| 7 | #define __LINUX_FDTABLE_H
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| 8 |
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| 9 | #include <linux/posix_types.h>
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| 10 | #include <linux/compiler.h>
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| 11 | #include <linux/spinlock.h>
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| 12 | #include <linux/rcupdate.h>
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| 13 | #include <linux/nospec.h>
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| 14 | #include <linux/types.h>
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| 15 | #include <linux/init.h>
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| 16 | #include <linux/fs.h>
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| 17 |
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| 18 | #include <linux/atomic.h>
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| 19 |
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| 20 | |
| 21 | * The default fd array needs to be at least BITS_PER_LONG,
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| 22 | * as this is the granularity returned by copy_fdset().
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| 23 |
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| 24 | #define NR_OPEN_DEFAULT BITS_PER_LONG
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| 25 |
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| 26 | struct fdtable {
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| 27 | unsigned int max_fds;
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| 28 | struct file __rcu **fd;
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| 29 | unsigned long *close_on_exec;
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| 30 | unsigned long *open_fds;
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| 31 | unsigned long *full_fds_bits;
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| 32 | struct rcu_head rcu;
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| 33 | };
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| 34 |
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| 35 | |
| 36 | * Open file table structure
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| 37 |
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| 38 | struct files_struct {
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| 39 | |
| 40 | * read mostly part
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| 41 |
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| 42 | atomic_t count;
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| 43 | bool resize_in_progress;
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| 44 | wait_queue_head_t resize_wait;
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| 45 |
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| 46 | struct fdtable __rcu *fdt;
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| 47 | struct fdtable fdtab;
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| 48 | |
| 49 | * written part on a separate cache line in SMP
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| 50 |
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| 51 | spinlock_t file_lock ____cacheline_aligned_in_smp;
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| 52 | unsigned int next_fd;
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| 53 | unsigned long close_on_exec_init[1];
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| 54 | unsigned long open_fds_init[1];
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| 55 | unsigned long full_fds_bits_init[1];
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| 56 | struct file __rcu * fd_array[NR_OPEN_DEFAULT];
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| 57 | };
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| 58 |
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| 59 | struct file_operations;
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| 60 | struct vfsmount;
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| 61 | struct dentry;
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| 62 |
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| 63 | #define rcu_dereference_check_fdtable(files, fdtfd) \
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| 64 | rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
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| 65 |
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| 66 | #define files_fdtable(files) \
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| 67 | rcu_dereference_check_fdtable((files), (files)->fdt)
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| 68 |
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| 69 | |
| 70 | * The caller must ensure that fd table isn't shared or hold rcu or file lock
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| 71 |
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| 72 | static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsigned int fd)
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| 73 | {
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| 74 | struct fdtable *fdt = rcu_dereference_raw(files->fdt);
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| 75 | unsigned long mask = array_index_mask_nospec(fd, fdt->max_fds);
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| 76 | struct file *needs_masking;
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| 77 |
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| 78 | |
| 79 | * 'mask' is zero for an out-of-bounds fd, all ones for ok.
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| 80 | * 'fd&mask' is 'fd' for ok, or 0 for out of bounds.
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| 81 | *
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| 82 | * Accessing fdt->fd[0] is ok, but needs masking of the result.
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| 83 |
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| 84 | needs_masking = rcu_dereference_raw(fdt->fd[fd&mask]);
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| 85 | return (struct file *)(mask & (unsigned long)needs_masking);
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| 86 | }
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| 87 |
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| 88 | static inline struct file *files_lookup_fd_locked(struct files_struct *files, unsigned int fd)
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| 89 | {
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| 90 | RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock),
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| 91 | "suspicious rcu_dereference_check() usage");
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| 92 | return files_lookup_fd_raw(files, fd);
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| 93 | }
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| 94 |
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| 95 | static inline bool close_on_exec(unsigned int fd, const struct files_struct *files)
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| 96 | {
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| 97 | return test_bit(fd, files_fdtable(files)->close_on_exec);
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| 98 | }
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| 99 |
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| 100 | struct task_struct;
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| 101 |
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| 102 | void put_files_struct(struct files_struct *fs);
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| 103 | int unshare_files(void);
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| 104 | struct fd_range {
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| 105 | unsigned int from, to;
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| 106 | };
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| 107 | struct files_struct *dup_fd(struct files_struct *, struct fd_range *) __latent_entropy;
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| 108 | void do_close_on_exec(struct files_struct *);
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| 109 | int iterate_fd(struct files_struct *, unsigned,
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| 110 | int (*)(const void *, struct file *, unsigned),
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| 111 | const void *);
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| 112 |
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| 113 | extern int close_fd(unsigned int fd);
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| 114 | extern struct file *file_close_fd(unsigned int fd);
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| 115 |
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| 116 | extern struct kmem_cache *files_cachep;
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| 117 |
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| 118 | #endif
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