linux/fs/stat.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/stat.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/blkdev.h>
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/cred.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/compat.h>
#include <linux/iversion.h>

#include <linux/uaccess.h>
#include <asm/unistd.h>

#include "internal.h"
#include "mount.h"

/**
 * generic_fillattr - Fill in the basic attributes from the inode struct
 * @idmap:		idmap of the mount the inode was found from
 * @request_mask:	statx request_mask
 * @inode:		Inode to use as the source
 * @stat:		Where to fill in the attributes
 *
 * Fill in the basic attributes in the kstat structure from data that's to be
 * found on the VFS inode structure.  This is the default if no getattr inode
 * operation is supplied.
 *
 * If the inode has been found through an idmapped mount the idmap of
 * the vfsmount must be passed through @idmap. This function will then
 * take care to map the inode according to @idmap before filling in the
 * uid and gid filds. On non-idmapped mounts or if permission checking is to be
 * performed on the raw inode simply pass @nop_mnt_idmap.
 */
void generic_fillattr(struct mnt_idmap *idmap, u32 request_mask,
		      struct inode *inode, struct kstat *stat)
{ … }
EXPORT_SYMBOL(…);

/**
 * generic_fill_statx_attr - Fill in the statx attributes from the inode flags
 * @inode:	Inode to use as the source
 * @stat:	Where to fill in the attribute flags
 *
 * Fill in the STATX_ATTR_* flags in the kstat structure for properties of the
 * inode that are published on i_flags and enforced by the VFS.
 */
void generic_fill_statx_attr(struct inode *inode, struct kstat *stat)
{ … }
EXPORT_SYMBOL(…);

/**
 * generic_fill_statx_atomic_writes - Fill in atomic writes statx attributes
 * @stat:	Where to fill in the attribute flags
 * @unit_min:	Minimum supported atomic write length in bytes
 * @unit_max:	Maximum supported atomic write length in bytes
 *
 * Fill in the STATX{_ATTR}_WRITE_ATOMIC flags in the kstat structure from
 * atomic write unit_min and unit_max values.
 */
void generic_fill_statx_atomic_writes(struct kstat *stat,
				      unsigned int unit_min,
				      unsigned int unit_max)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * vfs_getattr_nosec - getattr without security checks
 * @path: file to get attributes from
 * @stat: structure to return attributes in
 * @request_mask: STATX_xxx flags indicating what the caller wants
 * @query_flags: Query mode (AT_STATX_SYNC_TYPE)
 *
 * Get attributes without calling security_inode_getattr.
 *
 * Currently the only caller other than vfs_getattr is internal to the
 * filehandle lookup code, which uses only the inode number and returns no
 * attributes to any user.  Any other code probably wants vfs_getattr.
 */
int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
		      u32 request_mask, unsigned int query_flags)
{ … }
EXPORT_SYMBOL(…);

/*
 * vfs_getattr - Get the enhanced basic attributes of a file
 * @path: The file of interest
 * @stat: Where to return the statistics
 * @request_mask: STATX_xxx flags indicating what the caller wants
 * @query_flags: Query mode (AT_STATX_SYNC_TYPE)
 *
 * Ask the filesystem for a file's attributes.  The caller must indicate in
 * request_mask and query_flags to indicate what they want.
 *
 * If the file is remote, the filesystem can be forced to update the attributes
 * from the backing store by passing AT_STATX_FORCE_SYNC in query_flags or can
 * suppress the update by passing AT_STATX_DONT_SYNC.
 *
 * Bits must have been set in request_mask to indicate which attributes the
 * caller wants retrieving.  Any such attribute not requested may be returned
 * anyway, but the value may be approximate, and, if remote, may not have been
 * synchronised with the server.
 *
 * 0 will be returned on success, and a -ve error code if unsuccessful.
 */
int vfs_getattr(const struct path *path, struct kstat *stat,
		u32 request_mask, unsigned int query_flags)
{ … }
EXPORT_SYMBOL(…);

/**
 * vfs_fstat - Get the basic attributes by file descriptor
 * @fd: The file descriptor referring to the file of interest
 * @stat: The result structure to fill in.
 *
 * This function is a wrapper around vfs_getattr().  The main difference is
 * that it uses a file descriptor to determine the file location.
 *
 * 0 will be returned on success, and a -ve error code if unsuccessful.
 */
int vfs_fstat(int fd, struct kstat *stat)
{ … }

int getname_statx_lookup_flags(int flags)
{ … }

static int vfs_statx_path(struct path *path, int flags, struct kstat *stat,
			  u32 request_mask)
{ … }

static int vfs_statx_fd(int fd, int flags, struct kstat *stat,
			  u32 request_mask)
{ … }

/**
 * vfs_statx - Get basic and extra attributes by filename
 * @dfd: A file descriptor representing the base dir for a relative filename
 * @filename: The name of the file of interest
 * @flags: Flags to control the query
 * @stat: The result structure to fill in.
 * @request_mask: STATX_xxx flags indicating what the caller wants
 *
 * This function is a wrapper around vfs_getattr().  The main difference is
 * that it uses a filename and base directory to determine the file location.
 * Additionally, the use of AT_SYMLINK_NOFOLLOW in flags will prevent a symlink
 * at the given name from being referenced.
 *
 * 0 will be returned on success, and a -ve error code if unsuccessful.
 */
static int vfs_statx(int dfd, struct filename *filename, int flags,
	      struct kstat *stat, u32 request_mask)
{ … }

int vfs_fstatat(int dfd, const char __user *filename,
			      struct kstat *stat, int flags)
{ … }

#ifdef __ARCH_WANT_OLD_STAT

/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
{ … }

SYSCALL_DEFINE2(stat, const char __user *, filename,
		struct __old_kernel_stat __user *, statbuf)
{ … }

SYSCALL_DEFINE2(lstat, const char __user *, filename,
		struct __old_kernel_stat __user *, statbuf)
{ … }

SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
{ … }

#endif /* __ARCH_WANT_OLD_STAT */

#ifdef __ARCH_WANT_NEW_STAT

#ifndef INIT_STRUCT_STAT_PADDING
#define INIT_STRUCT_STAT_PADDING …
#endif

static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
{ … }

SYSCALL_DEFINE2(newstat, const char __user *, filename,
		struct stat __user *, statbuf)
{ … }

SYSCALL_DEFINE2(newlstat, const char __user *, filename,
		struct stat __user *, statbuf)
{ … }

#if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
		struct stat __user *, statbuf, int, flag)
{ … }
#endif

SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
{ … }
#endif

static int do_readlinkat(int dfd, const char __user *pathname,
			 char __user *buf, int bufsiz)
{ … }

SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
		char __user *, buf, int, bufsiz)
{ … }

SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
		int, bufsiz)
{ … }


/* ---------- LFS-64 ----------- */
#if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)

#ifndef INIT_STRUCT_STAT64_PADDING
#define INIT_STRUCT_STAT64_PADDING …
#endif

static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
{
	struct stat64 tmp;

	INIT_STRUCT_STAT64_PADDING(tmp);
#ifdef CONFIG_MIPS
	/* mips has weird padding, so we don't get 64 bits there */
	tmp.st_dev = new_encode_dev(stat->dev);
	tmp.st_rdev = new_encode_dev(stat->rdev);
#else
	tmp.st_dev = huge_encode_dev(stat->dev);
	tmp.st_rdev = huge_encode_dev(stat->rdev);
#endif
	tmp.st_ino = stat->ino;
	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
		return -EOVERFLOW;
#ifdef STAT64_HAS_BROKEN_ST_INO
	tmp.__st_ino = stat->ino;
#endif
	tmp.st_mode = stat->mode;
	tmp.st_nlink = stat->nlink;
	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
	tmp.st_atime = stat->atime.tv_sec;
	tmp.st_atime_nsec = stat->atime.tv_nsec;
	tmp.st_mtime = stat->mtime.tv_sec;
	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
	tmp.st_ctime = stat->ctime.tv_sec;
	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
	tmp.st_size = stat->size;
	tmp.st_blocks = stat->blocks;
	tmp.st_blksize = stat->blksize;
	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

SYSCALL_DEFINE2(stat64, const char __user *, filename,
		struct stat64 __user *, statbuf)
{
	struct kstat stat;
	int error = vfs_stat(filename, &stat);

	if (!error)
		error = cp_new_stat64(&stat, statbuf);

	return error;
}

SYSCALL_DEFINE2(lstat64, const char __user *, filename,
		struct stat64 __user *, statbuf)
{
	struct kstat stat;
	int error = vfs_lstat(filename, &stat);

	if (!error)
		error = cp_new_stat64(&stat, statbuf);

	return error;
}

SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
{
	struct kstat stat;
	int error = vfs_fstat(fd, &stat);

	if (!error)
		error = cp_new_stat64(&stat, statbuf);

	return error;
}

SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
		struct stat64 __user *, statbuf, int, flag)
{
	struct kstat stat;
	int error;

	error = vfs_fstatat(dfd, filename, &stat, flag);
	if (error)
		return error;
	return cp_new_stat64(&stat, statbuf);
}
#endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */

static noinline_for_stack int
cp_statx(const struct kstat *stat, struct statx __user *buffer)
{ … }

int do_statx(int dfd, struct filename *filename, unsigned int flags,
	     unsigned int mask, struct statx __user *buffer)
{ … }

int do_statx_fd(int fd, unsigned int flags, unsigned int mask,
	     struct statx __user *buffer)
{ … }

/**
 * sys_statx - System call to get enhanced stats
 * @dfd: Base directory to pathwalk from *or* fd to stat.
 * @filename: File to stat or either NULL or "" with AT_EMPTY_PATH
 * @flags: AT_* flags to control pathwalk.
 * @mask: Parts of statx struct actually required.
 * @buffer: Result buffer.
 *
 * Note that fstat() can be emulated by setting dfd to the fd of interest,
 * supplying "" (or preferably NULL) as the filename and setting AT_EMPTY_PATH
 * in the flags.
 */
SYSCALL_DEFINE5(statx,
		int, dfd, const char __user *, filename, unsigned, flags,
		unsigned int, mask,
		struct statx __user *, buffer)
{ … }

#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_STAT)
static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf)
{ … }

COMPAT_SYSCALL_DEFINE2(newstat, const char __user *, filename,
		       struct compat_stat __user *, statbuf)
{ … }

COMPAT_SYSCALL_DEFINE2(newlstat, const char __user *, filename,
		       struct compat_stat __user *, statbuf)
{ … }

#ifndef __ARCH_WANT_STAT64
COMPAT_SYSCALL_DEFINE4(newfstatat, unsigned int, dfd,
		       const char __user *, filename,
		       struct compat_stat __user *, statbuf, int, flag)
{ … }
#endif

COMPAT_SYSCALL_DEFINE2(newfstat, unsigned int, fd,
		       struct compat_stat __user *, statbuf)
{ … }
#endif

/* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
void __inode_add_bytes(struct inode *inode, loff_t bytes)
{ … }
EXPORT_SYMBOL(…);

void inode_add_bytes(struct inode *inode, loff_t bytes)
{ … }

EXPORT_SYMBOL(…);

void __inode_sub_bytes(struct inode *inode, loff_t bytes)
{ … }

EXPORT_SYMBOL(…);

void inode_sub_bytes(struct inode *inode, loff_t bytes)
{ … }

EXPORT_SYMBOL(…);

loff_t inode_get_bytes(struct inode *inode)
{ … }

EXPORT_SYMBOL(…);

void inode_set_bytes(struct inode *inode, loff_t bytes)
{ … }

EXPORT_SYMBOL(…);