[linux-block.git] / include / linux / fdtable.h

/* 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

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;
};

/*
 * 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);
	unsigned long mask = array_index_mask_nospec(fd, fdt->max_fds);
	struct file *needs_masking;

	/*
	 * 'mask' is zero for an out-of-bounds fd, all ones for ok.
	 * 'fd&mask' is 'fd' for ok, or 0 for out of bounds.
	 *
	 * Accessing fdt->fd[0] is ok, but needs masking of the result.
	 */
	needs_masking = rcu_dereference_raw(fdt->fd[fd&mask]);
	return (struct file *)(mask & (unsigned long)needs_masking);
}

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 bool close_on_exec(unsigned int fd, const struct files_struct *files)
{
	return test_bit(fd, files_fdtable(files)->close_on_exec);
}

struct task_struct;

void put_files_struct(struct files_struct *fs);
int unshare_files(void);
struct fd_range {
	unsigned int from, to;
};
struct files_struct *dup_fd(struct files_struct *, struct fd_range *) __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 close_fd(unsigned int fd);
extern struct file *file_close_fd(unsigned int fd);

extern struct kmem_cache *files_cachep;

#endif /* __LINUX_FDTABLE_H */
Commit	Line	Data
	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
	26	struct fdtable {
	27	unsigned int max_fds;
	28	struct file __rcu *fd; / current fd array */
	29	unsigned long *close_on_exec;
	30	unsigned long *open_fds;
	31	unsigned long *full_fds_bits;
	32	struct rcu_head rcu;
	33	};
	34
	35	/*
	36	* Open file table structure
	37	*/
	38	struct files_struct {
	39	/*
	40	* read mostly part
	41	*/
	42	atomic_t count;
	43	bool resize_in_progress;
	44	wait_queue_head_t resize_wait;
	45
	46	struct fdtable __rcu *fdt;
	47	struct fdtable fdtab;
	48	/*
	49	* written part on a separate cache line in SMP
	50	*/
	51	spinlock_t file_lock ____cacheline_aligned_in_smp;
	52	unsigned int next_fd;
	53	unsigned long close_on_exec_init[1];
	54	unsigned long open_fds_init[1];
	55	unsigned long full_fds_bits_init[1];
	56	struct file __rcu * fd_array[NR_OPEN_DEFAULT];
	57	};
	58
	59	struct file_operations;
	60	struct vfsmount;
	61	struct dentry;
	62
	63	#define rcu_dereference_check_fdtable(files, fdtfd) \
	64	rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
	65
	66	#define files_fdtable(files) \
	67	rcu_dereference_check_fdtable((files), (files)->fdt)
	68
	69	/*
	70	* The caller must ensure that fd table isn't shared or hold rcu or file lock
	71	*/
	72	static inline struct file files_lookup_fd_raw(struct files_struct files, unsigned int fd)
	73	{
	74	struct fdtable *fdt = rcu_dereference_raw(files->fdt);
	75	unsigned long mask = array_index_mask_nospec(fd, fdt->max_fds);
	76	struct file *needs_masking;
	77
	78	/*
	79	* 'mask' is zero for an out-of-bounds fd, all ones for ok.
	80	* 'fd&mask' is 'fd' for ok, or 0 for out of bounds.
	81	*
	82	* Accessing fdt->fd[0] is ok, but needs masking of the result.
	83	*/
	84	needs_masking = rcu_dereference_raw(fdt->fd[fd&mask]);
	85	return (struct file *)(mask & (unsigned long)needs_masking);
	86	}
	87
	88	static inline struct file files_lookup_fd_locked(struct files_struct files, unsigned int fd)
	89	{
	90	RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock),
	91	"suspicious rcu_dereference_check() usage");
	92	return files_lookup_fd_raw(files, fd);
	93	}
	94
	95	static inline bool close_on_exec(unsigned int fd, const struct files_struct *files)
	96	{
	97	return test_bit(fd, files_fdtable(files)->close_on_exec);
	98	}
	99
	100	struct task_struct;
	101
	102	void put_files_struct(struct files_struct *fs);
	103	int unshare_files(void);
	104	struct fd_range {
	105	unsigned int from, to;
	106	};
	107	struct files_struct dup_fd(struct files_struct , struct fd_range *) __latent_entropy;
	108	void do_close_on_exec(struct files_struct *);
	109	int iterate_fd(struct files_struct *, unsigned,
	110	int ()(const void , struct file *, unsigned),
	111	const void *);
	112
	113	extern int close_fd(unsigned int fd);
	114	extern struct file *file_close_fd(unsigned int fd);
	115
	116	extern struct kmem_cache *files_cachep;
	117
	118	#endif /* __LINUX_FDTABLE_H */