fdtable.h (3651B)
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 36static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt) 37{ 38 return test_bit(fd, fdt->close_on_exec); 39} 40 41static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt) 42{ 43 return test_bit(fd, fdt->open_fds); 44} 45 46/* 47 * Open file table structure 48 */ 49struct files_struct { 50 /* 51 * read mostly part 52 */ 53 atomic_t count; 54 bool resize_in_progress; 55 wait_queue_head_t resize_wait; 56 57 struct fdtable __rcu *fdt; 58 struct fdtable fdtab; 59 /* 60 * written part on a separate cache line in SMP 61 */ 62 spinlock_t file_lock ____cacheline_aligned_in_smp; 63 unsigned int next_fd; 64 unsigned long close_on_exec_init[1]; 65 unsigned long open_fds_init[1]; 66 unsigned long full_fds_bits_init[1]; 67 struct file __rcu * fd_array[NR_OPEN_DEFAULT]; 68}; 69 70struct file_operations; 71struct vfsmount; 72struct dentry; 73 74#define rcu_dereference_check_fdtable(files, fdtfd) \ 75 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock)) 76 77#define files_fdtable(files) \ 78 rcu_dereference_check_fdtable((files), (files)->fdt) 79 80/* 81 * The caller must ensure that fd table isn't shared or hold rcu or file lock 82 */ 83static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsigned int fd) 84{ 85 struct fdtable *fdt = rcu_dereference_raw(files->fdt); 86 87 if (fd < fdt->max_fds) { 88 fd = array_index_nospec(fd, fdt->max_fds); 89 return rcu_dereference_raw(fdt->fd[fd]); 90 } 91 return NULL; 92} 93 94static inline struct file *files_lookup_fd_locked(struct files_struct *files, unsigned int fd) 95{ 96 RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock), 97 "suspicious rcu_dereference_check() usage"); 98 return files_lookup_fd_raw(files, fd); 99} 100 101static inline struct file *files_lookup_fd_rcu(struct files_struct *files, unsigned int fd) 102{ 103 RCU_LOCKDEP_WARN(!rcu_read_lock_held(), 104 "suspicious rcu_dereference_check() usage"); 105 return files_lookup_fd_raw(files, fd); 106} 107 108static inline struct file *lookup_fd_rcu(unsigned int fd) 109{ 110 return files_lookup_fd_rcu(current->files, fd); 111} 112 113struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd); 114struct file *task_lookup_next_fd_rcu(struct task_struct *task, unsigned int *fd); 115 116struct task_struct; 117 118void put_files_struct(struct files_struct *fs); 119int unshare_files(void); 120struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy; 121void do_close_on_exec(struct files_struct *); 122int iterate_fd(struct files_struct *, unsigned, 123 int (*)(const void *, struct file *, unsigned), 124 const void *); 125 126extern int close_fd(unsigned int fd); 127extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags); 128extern struct file *close_fd_get_file(unsigned int fd); 129extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds, 130 struct files_struct **new_fdp); 131 132extern struct kmem_cache *files_cachep; 133 134#endif /* __LINUX_FDTABLE_H */