Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * descriptor table internals; you almost certainly want file.h instead.
4 */
5
6#ifndef __LINUX_FDTABLE_H
7#define __LINUX_FDTABLE_H
8
9#include <linux/posix_types.h>
10#include <linux/compiler.h>
11#include <linux/spinlock.h>
12#include <linux/rcupdate.h>
13#include <linux/nospec.h>
14#include <linux/types.h>
15#include <linux/init.h>
16#include <linux/fs.h>
17
18#include <linux/atomic.h>
19
20/*
21 * The default fd array needs to be at least BITS_PER_LONG,
22 * as this is the granularity returned by copy_fdset().
23 */
24#define NR_OPEN_DEFAULT BITS_PER_LONG
25#define NR_OPEN_MAX ~0U
26
27struct fdtable {
28 unsigned int max_fds;
29 struct file __rcu **fd; /* current fd array */
30 unsigned long *close_on_exec;
31 unsigned long *open_fds;
32 unsigned long *full_fds_bits;
33 struct rcu_head rcu;
34};
35
36/*
37 * Open file table structure
38 */
39struct files_struct {
40 /*
41 * read mostly part
42 */
43 atomic_t count;
44 bool resize_in_progress;
45 wait_queue_head_t resize_wait;
46
47 struct fdtable __rcu *fdt;
48 struct fdtable fdtab;
49 /*
50 * written part on a separate cache line in SMP
51 */
52 spinlock_t file_lock ____cacheline_aligned_in_smp;
53 unsigned int next_fd;
54 unsigned long close_on_exec_init[1];
55 unsigned long open_fds_init[1];
56 unsigned long full_fds_bits_init[1];
57 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
58};
59
60struct file_operations;
61struct vfsmount;
62struct dentry;
63
64#define rcu_dereference_check_fdtable(files, fdtfd) \
65 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
66
67#define files_fdtable(files) \
68 rcu_dereference_check_fdtable((files), (files)->fdt)
69
70/*
71 * The caller must ensure that fd table isn't shared or hold rcu or file lock
72 */
73static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsigned int fd)
74{
75 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
76 unsigned long mask = array_index_mask_nospec(fd, fdt->max_fds);
77 struct file *needs_masking;
78
79 /*
80 * 'mask' is zero for an out-of-bounds fd, all ones for ok.
81 * 'fd&mask' is 'fd' for ok, or 0 for out of bounds.
82 *
83 * Accessing fdt->fd[0] is ok, but needs masking of the result.
84 */
85 needs_masking = rcu_dereference_raw(fdt->fd[fd&mask]);
86 return (struct file *)(mask & (unsigned long)needs_masking);
87}
88
89static inline struct file *files_lookup_fd_locked(struct files_struct *files, unsigned int fd)
90{
91 RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock),
92 "suspicious rcu_dereference_check() usage");
93 return files_lookup_fd_raw(files, fd);
94}
95
96struct file *lookup_fdget_rcu(unsigned int fd);
97struct file *task_lookup_fdget_rcu(struct task_struct *task, unsigned int fd);
98struct file *task_lookup_next_fdget_rcu(struct task_struct *task, unsigned int *fd);
99
100static inline bool close_on_exec(unsigned int fd, const struct files_struct *files)
101{
102 return test_bit(fd, files_fdtable(files)->close_on_exec);
103}
104
105struct task_struct;
106
107void put_files_struct(struct files_struct *fs);
108int unshare_files(void);
109struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy;
110void do_close_on_exec(struct files_struct *);
111int iterate_fd(struct files_struct *, unsigned,
112 int (*)(const void *, struct file *, unsigned),
113 const void *);
114
115extern int close_fd(unsigned int fd);
116extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags);
117extern struct file *file_close_fd(unsigned int fd);
118extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
119 struct files_struct **new_fdp);
120
121extern struct kmem_cache *files_cachep;
122
123#endif /* __LINUX_FDTABLE_H */