e7b6caa186
[ Upstream commit f36c2943274199cb8aef32ac96531ffb7c4b43d0 ] This change renames fcheck_files to files_lookup_fd_rcu. All of the remaining callers take the rcu_read_lock before calling this function so the _rcu suffix is appropriate. This change also tightens up the debug check to verify that all callers hold the rcu_read_lock. All callers that used to call files_check with the files->file_lock held have now been changed to call files_lookup_fd_locked. This change of name has helped remind me of which locks and which guarantees are in place helping me to catch bugs later in the patchset. The need for better names became apparent in the last round of discussion of this set of changes[1]. [1] https://lkml.kernel.org/r/CAHk-=wj8BQbgJFLa+J0e=iT-1qpmCRTbPAJ8gd6MJQ=kbRPqyQ@mail.gmail.com Link: https://lkml.kernel.org/r/20201120231441.29911-9-ebiederm@xmission.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
137 lines
3.7 KiB
C
Executable file
137 lines
3.7 KiB
C
Executable file
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* descriptor table internals; you almost certainly want file.h instead.
|
|
*/
|
|
|
|
#ifndef __LINUX_FDTABLE_H
|
|
#define __LINUX_FDTABLE_H
|
|
|
|
#include <linux/posix_types.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/nospec.h>
|
|
#include <linux/types.h>
|
|
#include <linux/init.h>
|
|
#include <linux/fs.h>
|
|
|
|
#include <linux/atomic.h>
|
|
|
|
/*
|
|
* The default fd array needs to be at least BITS_PER_LONG,
|
|
* as this is the granularity returned by copy_fdset().
|
|
*/
|
|
#define NR_OPEN_DEFAULT BITS_PER_LONG
|
|
#define NR_OPEN_MAX ~0U
|
|
|
|
struct fdtable {
|
|
unsigned int max_fds;
|
|
struct file __rcu **fd; /* current fd array */
|
|
unsigned long *close_on_exec;
|
|
unsigned long *open_fds;
|
|
unsigned long *full_fds_bits;
|
|
struct rcu_head rcu;
|
|
};
|
|
|
|
static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt)
|
|
{
|
|
return test_bit(fd, fdt->close_on_exec);
|
|
}
|
|
|
|
static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt)
|
|
{
|
|
return test_bit(fd, fdt->open_fds);
|
|
}
|
|
|
|
/*
|
|
* Open file table structure
|
|
*/
|
|
struct files_struct {
|
|
/*
|
|
* read mostly part
|
|
*/
|
|
atomic_t count;
|
|
bool resize_in_progress;
|
|
wait_queue_head_t resize_wait;
|
|
|
|
struct fdtable __rcu *fdt;
|
|
struct fdtable fdtab;
|
|
/*
|
|
* written part on a separate cache line in SMP
|
|
*/
|
|
spinlock_t file_lock ____cacheline_aligned_in_smp;
|
|
unsigned int next_fd;
|
|
unsigned long close_on_exec_init[1];
|
|
unsigned long open_fds_init[1];
|
|
unsigned long full_fds_bits_init[1];
|
|
struct file __rcu * fd_array[NR_OPEN_DEFAULT];
|
|
};
|
|
|
|
struct file_operations;
|
|
struct vfsmount;
|
|
struct dentry;
|
|
|
|
#define rcu_dereference_check_fdtable(files, fdtfd) \
|
|
rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
|
|
|
|
#define files_fdtable(files) \
|
|
rcu_dereference_check_fdtable((files), (files)->fdt)
|
|
|
|
/*
|
|
* The caller must ensure that fd table isn't shared or hold rcu or file lock
|
|
*/
|
|
static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsigned int fd)
|
|
{
|
|
struct fdtable *fdt = rcu_dereference_raw(files->fdt);
|
|
|
|
if (fd < fdt->max_fds) {
|
|
fd = array_index_nospec(fd, fdt->max_fds);
|
|
return rcu_dereference_raw(fdt->fd[fd]);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static inline struct file *files_lookup_fd_locked(struct files_struct *files, unsigned int fd)
|
|
{
|
|
RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock),
|
|
"suspicious rcu_dereference_check() usage");
|
|
return files_lookup_fd_raw(files, fd);
|
|
}
|
|
|
|
static inline struct file *files_lookup_fd_rcu(struct files_struct *files, unsigned int fd)
|
|
{
|
|
RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
|
|
"suspicious rcu_dereference_check() usage");
|
|
return files_lookup_fd_raw(files, fd);
|
|
}
|
|
|
|
/*
|
|
* Check whether the specified fd has an open file.
|
|
*/
|
|
#define fcheck(fd) files_lookup_fd_rcu(current->files, fd)
|
|
|
|
struct task_struct;
|
|
|
|
struct files_struct *get_files_struct(struct task_struct *);
|
|
void put_files_struct(struct files_struct *fs);
|
|
int unshare_files(void);
|
|
struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy;
|
|
void do_close_on_exec(struct files_struct *);
|
|
int iterate_fd(struct files_struct *, unsigned,
|
|
int (*)(const void *, struct file *, unsigned),
|
|
const void *);
|
|
|
|
extern int __alloc_fd(struct files_struct *files,
|
|
unsigned start, unsigned end, unsigned flags);
|
|
extern void __fd_install(struct files_struct *files,
|
|
unsigned int fd, struct file *file);
|
|
extern int __close_fd(struct files_struct *files,
|
|
unsigned int fd);
|
|
extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags);
|
|
extern int close_fd_get_file(unsigned int fd, struct file **res);
|
|
extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
|
|
struct files_struct **new_fdp);
|
|
|
|
extern struct kmem_cache *files_cachep;
|
|
|
|
#endif /* __LINUX_FDTABLE_H */
|