linux/fs/stat.c
Linus Torvalds 590dce2d49 Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs 'statx()' update from Al Viro.

This adds the new extended stat() interface that internally subsumes our
previous stat interfaces, and allows user mode to specify in more detail
what kind of information it wants.

It also allows for some explicit synchronization information to be
passed to the filesystem, which can be relevant for network filesystems:
is the cached value ok, or do you need open/close consistency, or what?

From David Howells.

Andreas Dilger points out that the first version of the extended statx
interface was posted June 29, 2010:

    https://www.spinics.net/lists/linux-fsdevel/msg33831.html

* 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  statx: Add a system call to make enhanced file info available
2017-03-03 11:38:56 -08:00

651 lines
18 KiB
C

/*
* linux/fs/stat.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#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/uaccess.h>
#include <asm/unistd.h>
/**
* generic_fillattr - Fill in the basic attributes from the inode struct
* @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.
*/
void generic_fillattr(struct inode *inode, struct kstat *stat)
{
stat->dev = inode->i_sb->s_dev;
stat->ino = inode->i_ino;
stat->mode = inode->i_mode;
stat->nlink = inode->i_nlink;
stat->uid = inode->i_uid;
stat->gid = inode->i_gid;
stat->rdev = inode->i_rdev;
stat->size = i_size_read(inode);
stat->atime = inode->i_atime;
stat->mtime = inode->i_mtime;
stat->ctime = inode->i_ctime;
stat->blksize = i_blocksize(inode);
stat->blocks = inode->i_blocks;
if (IS_NOATIME(inode))
stat->result_mask &= ~STATX_ATIME;
if (IS_AUTOMOUNT(inode))
stat->attributes |= STATX_ATTR_AUTOMOUNT;
}
EXPORT_SYMBOL(generic_fillattr);
/**
* 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 (KSTAT_QUERY_FLAGS)
*
* 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)
{
struct inode *inode = d_backing_inode(path->dentry);
memset(stat, 0, sizeof(*stat));
stat->result_mask |= STATX_BASIC_STATS;
request_mask &= STATX_ALL;
query_flags &= KSTAT_QUERY_FLAGS;
if (inode->i_op->getattr)
return inode->i_op->getattr(path, stat, request_mask,
query_flags);
generic_fillattr(inode, stat);
return 0;
}
EXPORT_SYMBOL(vfs_getattr_nosec);
/*
* 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 (KSTAT_QUERY_FLAGS)
*
* 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)
{
int retval;
retval = security_inode_getattr(path);
if (retval)
return retval;
return vfs_getattr_nosec(path, stat, request_mask, query_flags);
}
EXPORT_SYMBOL(vfs_getattr);
/**
* vfs_statx_fd - Get the enhanced basic attributes by file descriptor
* @fd: The file descriptor referring to the file of interest
* @stat: The result structure to fill in.
* @request_mask: STATX_xxx flags indicating what the caller wants
* @query_flags: Query mode (KSTAT_QUERY_FLAGS)
*
* 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_statx_fd(unsigned int fd, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
struct fd f = fdget_raw(fd);
int error = -EBADF;
if (f.file) {
error = vfs_getattr(&f.file->f_path, stat,
request_mask, query_flags);
fdput(f);
}
return error;
}
EXPORT_SYMBOL(vfs_statx_fd);
/**
* 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.
*
* The caller must have preset stat->request_mask as for vfs_getattr(). The
* flags are also used to load up stat->query_flags.
*
* 0 will be returned on success, and a -ve error code if unsuccessful.
*/
int vfs_statx(int dfd, const char __user *filename, int flags,
struct kstat *stat, u32 request_mask)
{
struct path path;
int error = -EINVAL;
unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
return -EINVAL;
if (flags & AT_SYMLINK_NOFOLLOW)
lookup_flags &= ~LOOKUP_FOLLOW;
if (flags & AT_NO_AUTOMOUNT)
lookup_flags &= ~LOOKUP_AUTOMOUNT;
if (flags & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
retry:
error = user_path_at(dfd, filename, lookup_flags, &path);
if (error)
goto out;
error = vfs_getattr(&path, stat, request_mask, flags);
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
out:
return error;
}
EXPORT_SYMBOL(vfs_statx);
#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)
{
static int warncount = 5;
struct __old_kernel_stat tmp;
if (warncount > 0) {
warncount--;
printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
current->comm);
} else if (warncount < 0) {
/* it's laughable, but... */
warncount = 0;
}
memset(&tmp, 0, sizeof(struct __old_kernel_stat));
tmp.st_dev = old_encode_dev(stat->dev);
tmp.st_ino = stat->ino;
if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
return -EOVERFLOW;
tmp.st_mode = stat->mode;
tmp.st_nlink = stat->nlink;
if (tmp.st_nlink != stat->nlink)
return -EOVERFLOW;
SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
tmp.st_rdev = old_encode_dev(stat->rdev);
#if BITS_PER_LONG == 32
if (stat->size > MAX_NON_LFS)
return -EOVERFLOW;
#endif
tmp.st_size = stat->size;
tmp.st_atime = stat->atime.tv_sec;
tmp.st_mtime = stat->mtime.tv_sec;
tmp.st_ctime = stat->ctime.tv_sec;
return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}
SYSCALL_DEFINE2(stat, const char __user *, filename,
struct __old_kernel_stat __user *, statbuf)
{
struct kstat stat;
int error;
error = vfs_stat(filename, &stat);
if (error)
return error;
return cp_old_stat(&stat, statbuf);
}
SYSCALL_DEFINE2(lstat, const char __user *, filename,
struct __old_kernel_stat __user *, statbuf)
{
struct kstat stat;
int error;
error = vfs_lstat(filename, &stat);
if (error)
return error;
return cp_old_stat(&stat, statbuf);
}
SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
{
struct kstat stat;
int error = vfs_fstat(fd, &stat);
if (!error)
error = cp_old_stat(&stat, statbuf);
return error;
}
#endif /* __ARCH_WANT_OLD_STAT */
#if BITS_PER_LONG == 32
# define choose_32_64(a,b) a
#else
# define choose_32_64(a,b) b
#endif
#define valid_dev(x) choose_32_64(old_valid_dev(x),true)
#define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
#ifndef INIT_STRUCT_STAT_PADDING
# define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
#endif
static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
{
struct stat tmp;
if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
return -EOVERFLOW;
#if BITS_PER_LONG == 32
if (stat->size > MAX_NON_LFS)
return -EOVERFLOW;
#endif
INIT_STRUCT_STAT_PADDING(tmp);
tmp.st_dev = encode_dev(stat->dev);
tmp.st_ino = stat->ino;
if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
return -EOVERFLOW;
tmp.st_mode = stat->mode;
tmp.st_nlink = stat->nlink;
if (tmp.st_nlink != stat->nlink)
return -EOVERFLOW;
SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
tmp.st_rdev = encode_dev(stat->rdev);
tmp.st_size = stat->size;
tmp.st_atime = stat->atime.tv_sec;
tmp.st_mtime = stat->mtime.tv_sec;
tmp.st_ctime = stat->ctime.tv_sec;
#ifdef STAT_HAVE_NSEC
tmp.st_atime_nsec = stat->atime.tv_nsec;
tmp.st_mtime_nsec = stat->mtime.tv_nsec;
tmp.st_ctime_nsec = stat->ctime.tv_nsec;
#endif
tmp.st_blocks = stat->blocks;
tmp.st_blksize = stat->blksize;
return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}
SYSCALL_DEFINE2(newstat, const char __user *, filename,
struct stat __user *, statbuf)
{
struct kstat stat;
int error = vfs_stat(filename, &stat);
if (error)
return error;
return cp_new_stat(&stat, statbuf);
}
SYSCALL_DEFINE2(newlstat, const char __user *, filename,
struct stat __user *, statbuf)
{
struct kstat stat;
int error;
error = vfs_lstat(filename, &stat);
if (error)
return error;
return cp_new_stat(&stat, 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)
{
struct kstat stat;
int error;
error = vfs_fstatat(dfd, filename, &stat, flag);
if (error)
return error;
return cp_new_stat(&stat, statbuf);
}
#endif
SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
{
struct kstat stat;
int error = vfs_fstat(fd, &stat);
if (!error)
error = cp_new_stat(&stat, statbuf);
return error;
}
SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
char __user *, buf, int, bufsiz)
{
struct path path;
int error;
int empty = 0;
unsigned int lookup_flags = LOOKUP_EMPTY;
if (bufsiz <= 0)
return -EINVAL;
retry:
error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
if (!error) {
struct inode *inode = d_backing_inode(path.dentry);
error = empty ? -ENOENT : -EINVAL;
/*
* AFS mountpoints allow readlink(2) but are not symlinks
*/
if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
error = security_inode_readlink(path.dentry);
if (!error) {
touch_atime(&path);
error = vfs_readlink(path.dentry, buf, bufsiz);
}
}
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
}
return error;
}
SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
int, bufsiz)
{
return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
}
/* ---------- LFS-64 ----------- */
#if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)
#ifndef INIT_STRUCT_STAT64_PADDING
# define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
#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 inline int __put_timestamp(struct timespec *kts,
struct statx_timestamp __user *uts)
{
return (__put_user(kts->tv_sec, &uts->tv_sec ) ||
__put_user(kts->tv_nsec, &uts->tv_nsec ) ||
__put_user(0, &uts->__reserved ));
}
/*
* Set the statx results.
*/
static long statx_set_result(struct kstat *stat, struct statx __user *buffer)
{
uid_t uid = from_kuid_munged(current_user_ns(), stat->uid);
gid_t gid = from_kgid_munged(current_user_ns(), stat->gid);
if (__put_user(stat->result_mask, &buffer->stx_mask ) ||
__put_user(stat->mode, &buffer->stx_mode ) ||
__clear_user(&buffer->__spare0, sizeof(buffer->__spare0)) ||
__put_user(stat->nlink, &buffer->stx_nlink ) ||
__put_user(uid, &buffer->stx_uid ) ||
__put_user(gid, &buffer->stx_gid ) ||
__put_user(stat->attributes, &buffer->stx_attributes ) ||
__put_user(stat->blksize, &buffer->stx_blksize ) ||
__put_user(MAJOR(stat->rdev), &buffer->stx_rdev_major ) ||
__put_user(MINOR(stat->rdev), &buffer->stx_rdev_minor ) ||
__put_user(MAJOR(stat->dev), &buffer->stx_dev_major ) ||
__put_user(MINOR(stat->dev), &buffer->stx_dev_minor ) ||
__put_timestamp(&stat->atime, &buffer->stx_atime ) ||
__put_timestamp(&stat->btime, &buffer->stx_btime ) ||
__put_timestamp(&stat->ctime, &buffer->stx_ctime ) ||
__put_timestamp(&stat->mtime, &buffer->stx_mtime ) ||
__put_user(stat->ino, &buffer->stx_ino ) ||
__put_user(stat->size, &buffer->stx_size ) ||
__put_user(stat->blocks, &buffer->stx_blocks ) ||
__clear_user(&buffer->__spare1, sizeof(buffer->__spare1)) ||
__clear_user(&buffer->__spare2, sizeof(buffer->__spare2)))
return -EFAULT;
return 0;
}
/**
* sys_statx - System call to get enhanced stats
* @dfd: Base directory to pathwalk from *or* fd to stat.
* @filename: File to stat *or* NULL.
* @flags: AT_* flags to control pathwalk.
* @mask: Parts of statx struct actually required.
* @buffer: Result buffer.
*
* Note that if filename is NULL, then it does the equivalent of fstat() using
* dfd to indicate the file of interest.
*/
SYSCALL_DEFINE5(statx,
int, dfd, const char __user *, filename, unsigned, flags,
unsigned int, mask,
struct statx __user *, buffer)
{
struct kstat stat;
int error;
if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
return -EINVAL;
if (!access_ok(VERIFY_WRITE, buffer, sizeof(*buffer)))
return -EFAULT;
if (filename)
error = vfs_statx(dfd, filename, flags, &stat, mask);
else
error = vfs_statx_fd(dfd, &stat, mask, flags);
if (error)
return error;
return statx_set_result(&stat, buffer);
}
/* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
void __inode_add_bytes(struct inode *inode, loff_t bytes)
{
inode->i_blocks += bytes >> 9;
bytes &= 511;
inode->i_bytes += bytes;
if (inode->i_bytes >= 512) {
inode->i_blocks++;
inode->i_bytes -= 512;
}
}
void inode_add_bytes(struct inode *inode, loff_t bytes)
{
spin_lock(&inode->i_lock);
__inode_add_bytes(inode, bytes);
spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(inode_add_bytes);
void __inode_sub_bytes(struct inode *inode, loff_t bytes)
{
inode->i_blocks -= bytes >> 9;
bytes &= 511;
if (inode->i_bytes < bytes) {
inode->i_blocks--;
inode->i_bytes += 512;
}
inode->i_bytes -= bytes;
}
EXPORT_SYMBOL(__inode_sub_bytes);
void inode_sub_bytes(struct inode *inode, loff_t bytes)
{
spin_lock(&inode->i_lock);
__inode_sub_bytes(inode, bytes);
spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(inode_sub_bytes);
loff_t inode_get_bytes(struct inode *inode)
{
loff_t ret;
spin_lock(&inode->i_lock);
ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
spin_unlock(&inode->i_lock);
return ret;
}
EXPORT_SYMBOL(inode_get_bytes);
void inode_set_bytes(struct inode *inode, loff_t bytes)
{
/* Caller is here responsible for sufficient locking
* (ie. inode->i_lock) */
inode->i_blocks = bytes >> 9;
inode->i_bytes = bytes & 511;
}
EXPORT_SYMBOL(inode_set_bytes);