linux/fs/open.c
Aleksa Sarai f92f0a1b05
openat2: explicitly return -E2BIG for (usize > PAGE_SIZE)
While we do currently return -EFAULT in this case, it seems prudent to
follow the behaviour of other syscalls like clone3. It seems quite
unlikely that anyone depends on this error code being EFAULT, but we can
always revert this if it turns out to be an issue.

Cc: stable@vger.kernel.org # v5.6+
Fixes: fddb5d430a ("open: introduce openat2(2) syscall")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Link: https://lore.kernel.org/r/20241010-extensible-structs-check_fields-v3-3-d2833dfe6edd@cyphar.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-10 12:09:03 +02:00

1656 lines
40 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/fs/open.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/fsnotify.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/namei.h>
#include <linux/backing-dev.h>
#include <linux/capability.h>
#include <linux/securebits.h>
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/personality.h>
#include <linux/pagemap.h>
#include <linux/syscalls.h>
#include <linux/rcupdate.h>
#include <linux/audit.h>
#include <linux/falloc.h>
#include <linux/fs_struct.h>
#include <linux/dnotify.h>
#include <linux/compat.h>
#include <linux/mnt_idmapping.h>
#include <linux/filelock.h>
#include "internal.h"
int do_truncate(struct mnt_idmap *idmap, struct dentry *dentry,
loff_t length, unsigned int time_attrs, struct file *filp)
{
int ret;
struct iattr newattrs;
/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
if (length < 0)
return -EINVAL;
newattrs.ia_size = length;
newattrs.ia_valid = ATTR_SIZE | time_attrs;
if (filp) {
newattrs.ia_file = filp;
newattrs.ia_valid |= ATTR_FILE;
}
/* Remove suid, sgid, and file capabilities on truncate too */
ret = dentry_needs_remove_privs(idmap, dentry);
if (ret < 0)
return ret;
if (ret)
newattrs.ia_valid |= ret | ATTR_FORCE;
inode_lock(dentry->d_inode);
/* Note any delegations or leases have already been broken: */
ret = notify_change(idmap, dentry, &newattrs, NULL);
inode_unlock(dentry->d_inode);
return ret;
}
long vfs_truncate(const struct path *path, loff_t length)
{
struct mnt_idmap *idmap;
struct inode *inode;
long error;
inode = path->dentry->d_inode;
/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
if (S_ISDIR(inode->i_mode))
return -EISDIR;
if (!S_ISREG(inode->i_mode))
return -EINVAL;
error = mnt_want_write(path->mnt);
if (error)
goto out;
idmap = mnt_idmap(path->mnt);
error = inode_permission(idmap, inode, MAY_WRITE);
if (error)
goto mnt_drop_write_and_out;
error = -EPERM;
if (IS_APPEND(inode))
goto mnt_drop_write_and_out;
error = get_write_access(inode);
if (error)
goto mnt_drop_write_and_out;
/*
* Make sure that there are no leases. get_write_access() protects
* against the truncate racing with a lease-granting setlease().
*/
error = break_lease(inode, O_WRONLY);
if (error)
goto put_write_and_out;
error = security_path_truncate(path);
if (!error)
error = do_truncate(idmap, path->dentry, length, 0, NULL);
put_write_and_out:
put_write_access(inode);
mnt_drop_write_and_out:
mnt_drop_write(path->mnt);
out:
return error;
}
EXPORT_SYMBOL_GPL(vfs_truncate);
long do_sys_truncate(const char __user *pathname, loff_t length)
{
unsigned int lookup_flags = LOOKUP_FOLLOW;
struct path path;
int error;
if (length < 0) /* sorry, but loff_t says... */
return -EINVAL;
retry:
error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
if (!error) {
error = vfs_truncate(&path, length);
path_put(&path);
}
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
return error;
}
SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
{
return do_sys_truncate(path, length);
}
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
{
return do_sys_truncate(path, length);
}
#endif
long do_ftruncate(struct file *file, loff_t length, int small)
{
struct inode *inode;
struct dentry *dentry;
int error;
/* explicitly opened as large or we are on 64-bit box */
if (file->f_flags & O_LARGEFILE)
small = 0;
dentry = file->f_path.dentry;
inode = dentry->d_inode;
if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
return -EINVAL;
/* Cannot ftruncate over 2^31 bytes without large file support */
if (small && length > MAX_NON_LFS)
return -EINVAL;
/* Check IS_APPEND on real upper inode */
if (IS_APPEND(file_inode(file)))
return -EPERM;
sb_start_write(inode->i_sb);
error = security_file_truncate(file);
if (!error)
error = do_truncate(file_mnt_idmap(file), dentry, length,
ATTR_MTIME | ATTR_CTIME, file);
sb_end_write(inode->i_sb);
return error;
}
long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
{
struct fd f;
int error;
if (length < 0)
return -EINVAL;
f = fdget(fd);
if (!fd_file(f))
return -EBADF;
error = do_ftruncate(fd_file(f), length, small);
fdput(f);
return error;
}
SYSCALL_DEFINE2(ftruncate, unsigned int, fd, off_t, length)
{
return do_sys_ftruncate(fd, length, 1);
}
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_off_t, length)
{
return do_sys_ftruncate(fd, length, 1);
}
#endif
/* LFS versions of truncate are only needed on 32 bit machines */
#if BITS_PER_LONG == 32
SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
{
return do_sys_truncate(path, length);
}
SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
{
return do_sys_ftruncate(fd, length, 0);
}
#endif /* BITS_PER_LONG == 32 */
#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
compat_arg_u64_dual(length))
{
return ksys_truncate(pathname, compat_arg_u64_glue(length));
}
#endif
#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
compat_arg_u64_dual(length))
{
return ksys_ftruncate(fd, compat_arg_u64_glue(length));
}
#endif
int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
{
struct inode *inode = file_inode(file);
long ret;
loff_t sum;
if (offset < 0 || len <= 0)
return -EINVAL;
if (mode & ~(FALLOC_FL_MODE_MASK | FALLOC_FL_KEEP_SIZE))
return -EOPNOTSUPP;
/*
* Modes are exclusive, even if that is not obvious from the encoding
* as bit masks and the mix with the flag in the same namespace.
*
* To make things even more complicated, FALLOC_FL_ALLOCATE_RANGE is
* encoded as no bit set.
*/
switch (mode & FALLOC_FL_MODE_MASK) {
case FALLOC_FL_ALLOCATE_RANGE:
case FALLOC_FL_UNSHARE_RANGE:
case FALLOC_FL_ZERO_RANGE:
break;
case FALLOC_FL_PUNCH_HOLE:
if (!(mode & FALLOC_FL_KEEP_SIZE))
return -EOPNOTSUPP;
break;
case FALLOC_FL_COLLAPSE_RANGE:
case FALLOC_FL_INSERT_RANGE:
if (mode & FALLOC_FL_KEEP_SIZE)
return -EOPNOTSUPP;
break;
default:
return -EOPNOTSUPP;
}
if (!(file->f_mode & FMODE_WRITE))
return -EBADF;
/*
* On append-only files only space preallocation is supported.
*/
if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
return -EPERM;
if (IS_IMMUTABLE(inode))
return -EPERM;
/*
* We cannot allow any fallocate operation on an active swapfile
*/
if (IS_SWAPFILE(inode))
return -ETXTBSY;
/*
* Revalidate the write permissions, in case security policy has
* changed since the files were opened.
*/
ret = security_file_permission(file, MAY_WRITE);
if (ret)
return ret;
ret = fsnotify_file_area_perm(file, MAY_WRITE, &offset, len);
if (ret)
return ret;
if (S_ISFIFO(inode->i_mode))
return -ESPIPE;
if (S_ISDIR(inode->i_mode))
return -EISDIR;
if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
return -ENODEV;
/* Check for wraparound */
if (check_add_overflow(offset, len, &sum))
return -EFBIG;
if (sum > inode->i_sb->s_maxbytes)
return -EFBIG;
if (!file->f_op->fallocate)
return -EOPNOTSUPP;
file_start_write(file);
ret = file->f_op->fallocate(file, mode, offset, len);
/*
* Create inotify and fanotify events.
*
* To keep the logic simple always create events if fallocate succeeds.
* This implies that events are even created if the file size remains
* unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
*/
if (ret == 0)
fsnotify_modify(file);
file_end_write(file);
return ret;
}
EXPORT_SYMBOL_GPL(vfs_fallocate);
int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
{
struct fd f = fdget(fd);
int error = -EBADF;
if (fd_file(f)) {
error = vfs_fallocate(fd_file(f), mode, offset, len);
fdput(f);
}
return error;
}
SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
{
return ksys_fallocate(fd, mode, offset, len);
}
#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
compat_arg_u64_dual(len))
{
return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
compat_arg_u64_glue(len));
}
#endif
/*
* access() needs to use the real uid/gid, not the effective uid/gid.
* We do this by temporarily clearing all FS-related capabilities and
* switching the fsuid/fsgid around to the real ones.
*
* Creating new credentials is expensive, so we try to skip doing it,
* which we can if the result would match what we already got.
*/
static bool access_need_override_creds(int flags)
{
const struct cred *cred;
if (flags & AT_EACCESS)
return false;
cred = current_cred();
if (!uid_eq(cred->fsuid, cred->uid) ||
!gid_eq(cred->fsgid, cred->gid))
return true;
if (!issecure(SECURE_NO_SETUID_FIXUP)) {
kuid_t root_uid = make_kuid(cred->user_ns, 0);
if (!uid_eq(cred->uid, root_uid)) {
if (!cap_isclear(cred->cap_effective))
return true;
} else {
if (!cap_isidentical(cred->cap_effective,
cred->cap_permitted))
return true;
}
}
return false;
}
static const struct cred *access_override_creds(void)
{
const struct cred *old_cred;
struct cred *override_cred;
override_cred = prepare_creds();
if (!override_cred)
return NULL;
/*
* XXX access_need_override_creds performs checks in hopes of skipping
* this work. Make sure it stays in sync if making any changes in this
* routine.
*/
override_cred->fsuid = override_cred->uid;
override_cred->fsgid = override_cred->gid;
if (!issecure(SECURE_NO_SETUID_FIXUP)) {
/* Clear the capabilities if we switch to a non-root user */
kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
if (!uid_eq(override_cred->uid, root_uid))
cap_clear(override_cred->cap_effective);
else
override_cred->cap_effective =
override_cred->cap_permitted;
}
/*
* The new set of credentials can *only* be used in
* task-synchronous circumstances, and does not need
* RCU freeing, unless somebody then takes a separate
* reference to it.
*
* NOTE! This is _only_ true because this credential
* is used purely for override_creds() that installs
* it as the subjective cred. Other threads will be
* accessing ->real_cred, not the subjective cred.
*
* If somebody _does_ make a copy of this (using the
* 'get_current_cred()' function), that will clear the
* non_rcu field, because now that other user may be
* expecting RCU freeing. But normal thread-synchronous
* cred accesses will keep things non-racy to avoid RCU
* freeing.
*/
override_cred->non_rcu = 1;
old_cred = override_creds(override_cred);
/* override_cred() gets its own ref */
put_cred(override_cred);
return old_cred;
}
static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
{
struct path path;
struct inode *inode;
int res;
unsigned int lookup_flags = LOOKUP_FOLLOW;
const struct cred *old_cred = NULL;
if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
return -EINVAL;
if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
return -EINVAL;
if (flags & AT_SYMLINK_NOFOLLOW)
lookup_flags &= ~LOOKUP_FOLLOW;
if (flags & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
if (access_need_override_creds(flags)) {
old_cred = access_override_creds();
if (!old_cred)
return -ENOMEM;
}
retry:
res = user_path_at(dfd, filename, lookup_flags, &path);
if (res)
goto out;
inode = d_backing_inode(path.dentry);
if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
/*
* MAY_EXEC on regular files is denied if the fs is mounted
* with the "noexec" flag.
*/
res = -EACCES;
if (path_noexec(&path))
goto out_path_release;
}
res = inode_permission(mnt_idmap(path.mnt), inode, mode | MAY_ACCESS);
/* SuS v2 requires we report a read only fs too */
if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
goto out_path_release;
/*
* This is a rare case where using __mnt_is_readonly()
* is OK without a mnt_want/drop_write() pair. Since
* no actual write to the fs is performed here, we do
* not need to telegraph to that to anyone.
*
* By doing this, we accept that this access is
* inherently racy and know that the fs may change
* state before we even see this result.
*/
if (__mnt_is_readonly(path.mnt))
res = -EROFS;
out_path_release:
path_put(&path);
if (retry_estale(res, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
out:
if (old_cred)
revert_creds(old_cred);
return res;
}
SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
{
return do_faccessat(dfd, filename, mode, 0);
}
SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
int, flags)
{
return do_faccessat(dfd, filename, mode, flags);
}
SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
{
return do_faccessat(AT_FDCWD, filename, mode, 0);
}
SYSCALL_DEFINE1(chdir, const char __user *, filename)
{
struct path path;
int error;
unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
retry:
error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
if (error)
goto out;
error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
if (error)
goto dput_and_out;
set_fs_pwd(current->fs, &path);
dput_and_out:
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
out:
return error;
}
SYSCALL_DEFINE1(fchdir, unsigned int, fd)
{
struct fd f = fdget_raw(fd);
int error;
error = -EBADF;
if (!fd_file(f))
goto out;
error = -ENOTDIR;
if (!d_can_lookup(fd_file(f)->f_path.dentry))
goto out_putf;
error = file_permission(fd_file(f), MAY_EXEC | MAY_CHDIR);
if (!error)
set_fs_pwd(current->fs, &fd_file(f)->f_path);
out_putf:
fdput(f);
out:
return error;
}
SYSCALL_DEFINE1(chroot, const char __user *, filename)
{
struct path path;
int error;
unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
retry:
error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
if (error)
goto out;
error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
if (error)
goto dput_and_out;
error = -EPERM;
if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
goto dput_and_out;
error = security_path_chroot(&path);
if (error)
goto dput_and_out;
set_fs_root(current->fs, &path);
error = 0;
dput_and_out:
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
out:
return error;
}
int chmod_common(const struct path *path, umode_t mode)
{
struct inode *inode = path->dentry->d_inode;
struct inode *delegated_inode = NULL;
struct iattr newattrs;
int error;
error = mnt_want_write(path->mnt);
if (error)
return error;
retry_deleg:
inode_lock(inode);
error = security_path_chmod(path, mode);
if (error)
goto out_unlock;
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
error = notify_change(mnt_idmap(path->mnt), path->dentry,
&newattrs, &delegated_inode);
out_unlock:
inode_unlock(inode);
if (delegated_inode) {
error = break_deleg_wait(&delegated_inode);
if (!error)
goto retry_deleg;
}
mnt_drop_write(path->mnt);
return error;
}
int vfs_fchmod(struct file *file, umode_t mode)
{
audit_file(file);
return chmod_common(&file->f_path, mode);
}
SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
{
struct fd f = fdget(fd);
int err = -EBADF;
if (fd_file(f)) {
err = vfs_fchmod(fd_file(f), mode);
fdput(f);
}
return err;
}
static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
unsigned int flags)
{
struct path path;
int error;
unsigned int lookup_flags;
if (unlikely(flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)))
return -EINVAL;
lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
if (flags & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
retry:
error = user_path_at(dfd, filename, lookup_flags, &path);
if (!error) {
error = chmod_common(&path, mode);
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
}
return error;
}
SYSCALL_DEFINE4(fchmodat2, int, dfd, const char __user *, filename,
umode_t, mode, unsigned int, flags)
{
return do_fchmodat(dfd, filename, mode, flags);
}
SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
umode_t, mode)
{
return do_fchmodat(dfd, filename, mode, 0);
}
SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
{
return do_fchmodat(AT_FDCWD, filename, mode, 0);
}
/*
* Check whether @kuid is valid and if so generate and set vfsuid_t in
* ia_vfsuid.
*
* Return: true if @kuid is valid, false if not.
*/
static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid)
{
if (!uid_valid(kuid))
return false;
attr->ia_valid |= ATTR_UID;
attr->ia_vfsuid = VFSUIDT_INIT(kuid);
return true;
}
/*
* Check whether @kgid is valid and if so generate and set vfsgid_t in
* ia_vfsgid.
*
* Return: true if @kgid is valid, false if not.
*/
static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
{
if (!gid_valid(kgid))
return false;
attr->ia_valid |= ATTR_GID;
attr->ia_vfsgid = VFSGIDT_INIT(kgid);
return true;
}
int chown_common(const struct path *path, uid_t user, gid_t group)
{
struct mnt_idmap *idmap;
struct user_namespace *fs_userns;
struct inode *inode = path->dentry->d_inode;
struct inode *delegated_inode = NULL;
int error;
struct iattr newattrs;
kuid_t uid;
kgid_t gid;
uid = make_kuid(current_user_ns(), user);
gid = make_kgid(current_user_ns(), group);
idmap = mnt_idmap(path->mnt);
fs_userns = i_user_ns(inode);
retry_deleg:
newattrs.ia_vfsuid = INVALID_VFSUID;
newattrs.ia_vfsgid = INVALID_VFSGID;
newattrs.ia_valid = ATTR_CTIME;
if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid))
return -EINVAL;
if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid))
return -EINVAL;
inode_lock(inode);
if (!S_ISDIR(inode->i_mode))
newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
setattr_should_drop_sgid(idmap, inode);
/* Continue to send actual fs values, not the mount values. */
error = security_path_chown(
path,
from_vfsuid(idmap, fs_userns, newattrs.ia_vfsuid),
from_vfsgid(idmap, fs_userns, newattrs.ia_vfsgid));
if (!error)
error = notify_change(idmap, path->dentry, &newattrs,
&delegated_inode);
inode_unlock(inode);
if (delegated_inode) {
error = break_deleg_wait(&delegated_inode);
if (!error)
goto retry_deleg;
}
return error;
}
int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
int flag)
{
struct path path;
int error = -EINVAL;
int lookup_flags;
if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
goto out;
lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
if (flag & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
retry:
error = user_path_at(dfd, filename, lookup_flags, &path);
if (error)
goto out;
error = mnt_want_write(path.mnt);
if (error)
goto out_release;
error = chown_common(&path, user, group);
mnt_drop_write(path.mnt);
out_release:
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
out:
return error;
}
SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
gid_t, group, int, flag)
{
return do_fchownat(dfd, filename, user, group, flag);
}
SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
{
return do_fchownat(AT_FDCWD, filename, user, group, 0);
}
SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
{
return do_fchownat(AT_FDCWD, filename, user, group,
AT_SYMLINK_NOFOLLOW);
}
int vfs_fchown(struct file *file, uid_t user, gid_t group)
{
int error;
error = mnt_want_write_file(file);
if (error)
return error;
audit_file(file);
error = chown_common(&file->f_path, user, group);
mnt_drop_write_file(file);
return error;
}
int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
{
struct fd f = fdget(fd);
int error = -EBADF;
if (fd_file(f)) {
error = vfs_fchown(fd_file(f), user, group);
fdput(f);
}
return error;
}
SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
{
return ksys_fchown(fd, user, group);
}
static inline int file_get_write_access(struct file *f)
{
int error;
error = get_write_access(f->f_inode);
if (unlikely(error))
return error;
error = mnt_get_write_access(f->f_path.mnt);
if (unlikely(error))
goto cleanup_inode;
if (unlikely(f->f_mode & FMODE_BACKING)) {
error = mnt_get_write_access(backing_file_user_path(f)->mnt);
if (unlikely(error))
goto cleanup_mnt;
}
return 0;
cleanup_mnt:
mnt_put_write_access(f->f_path.mnt);
cleanup_inode:
put_write_access(f->f_inode);
return error;
}
static int do_dentry_open(struct file *f,
int (*open)(struct inode *, struct file *))
{
static const struct file_operations empty_fops = {};
struct inode *inode = f->f_path.dentry->d_inode;
int error;
path_get(&f->f_path);
f->f_inode = inode;
f->f_mapping = inode->i_mapping;
f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
f->f_sb_err = file_sample_sb_err(f);
if (unlikely(f->f_flags & O_PATH)) {
f->f_mode = FMODE_PATH | FMODE_OPENED;
f->f_op = &empty_fops;
return 0;
}
if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
i_readcount_inc(inode);
} else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
error = file_get_write_access(f);
if (unlikely(error))
goto cleanup_file;
f->f_mode |= FMODE_WRITER;
}
/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
f->f_mode |= FMODE_ATOMIC_POS;
f->f_op = fops_get(inode->i_fop);
if (WARN_ON(!f->f_op)) {
error = -ENODEV;
goto cleanup_all;
}
error = security_file_open(f);
if (error)
goto cleanup_all;
error = break_lease(file_inode(f), f->f_flags);
if (error)
goto cleanup_all;
/* normally all 3 are set; ->open() can clear them if needed */
f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
if (!open)
open = f->f_op->open;
if (open) {
error = open(inode, f);
if (error)
goto cleanup_all;
}
f->f_mode |= FMODE_OPENED;
if ((f->f_mode & FMODE_READ) &&
likely(f->f_op->read || f->f_op->read_iter))
f->f_mode |= FMODE_CAN_READ;
if ((f->f_mode & FMODE_WRITE) &&
likely(f->f_op->write || f->f_op->write_iter))
f->f_mode |= FMODE_CAN_WRITE;
if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
f->f_mode &= ~FMODE_LSEEK;
if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
f->f_mode |= FMODE_CAN_ODIRECT;
f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
f->f_iocb_flags = iocb_flags(f);
file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
return -EINVAL;
/*
* XXX: Huge page cache doesn't support writing yet. Drop all page
* cache for this file before processing writes.
*/
if (f->f_mode & FMODE_WRITE) {
/*
* Depends on full fence from get_write_access() to synchronize
* against collapse_file() regarding i_writecount and nr_thps
* updates. Ensures subsequent insertion of THPs into the page
* cache will fail.
*/
if (filemap_nr_thps(inode->i_mapping)) {
struct address_space *mapping = inode->i_mapping;
filemap_invalidate_lock(inode->i_mapping);
/*
* unmap_mapping_range just need to be called once
* here, because the private pages is not need to be
* unmapped mapping (e.g. data segment of dynamic
* shared libraries here).
*/
unmap_mapping_range(mapping, 0, 0, 0);
truncate_inode_pages(mapping, 0);
filemap_invalidate_unlock(inode->i_mapping);
}
}
return 0;
cleanup_all:
if (WARN_ON_ONCE(error > 0))
error = -EINVAL;
fops_put(f->f_op);
put_file_access(f);
cleanup_file:
path_put(&f->f_path);
f->f_path.mnt = NULL;
f->f_path.dentry = NULL;
f->f_inode = NULL;
return error;
}
/**
* finish_open - finish opening a file
* @file: file pointer
* @dentry: pointer to dentry
* @open: open callback
*
* This can be used to finish opening a file passed to i_op->atomic_open().
*
* If the open callback is set to NULL, then the standard f_op->open()
* filesystem callback is substituted.
*
* NB: the dentry reference is _not_ consumed. If, for example, the dentry is
* the return value of d_splice_alias(), then the caller needs to perform dput()
* on it after finish_open().
*
* Returns zero on success or -errno if the open failed.
*/
int finish_open(struct file *file, struct dentry *dentry,
int (*open)(struct inode *, struct file *))
{
BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
file->f_path.dentry = dentry;
return do_dentry_open(file, open);
}
EXPORT_SYMBOL(finish_open);
/**
* finish_no_open - finish ->atomic_open() without opening the file
*
* @file: file pointer
* @dentry: dentry or NULL (as returned from ->lookup())
*
* This can be used to set the result of a successful lookup in ->atomic_open().
*
* NB: unlike finish_open() this function does consume the dentry reference and
* the caller need not dput() it.
*
* Returns "0" which must be the return value of ->atomic_open() after having
* called this function.
*/
int finish_no_open(struct file *file, struct dentry *dentry)
{
file->f_path.dentry = dentry;
return 0;
}
EXPORT_SYMBOL(finish_no_open);
char *file_path(struct file *filp, char *buf, int buflen)
{
return d_path(&filp->f_path, buf, buflen);
}
EXPORT_SYMBOL(file_path);
/**
* vfs_open - open the file at the given path
* @path: path to open
* @file: newly allocated file with f_flag initialized
*/
int vfs_open(const struct path *path, struct file *file)
{
int ret;
file->f_path = *path;
ret = do_dentry_open(file, NULL);
if (!ret) {
/*
* Once we return a file with FMODE_OPENED, __fput() will call
* fsnotify_close(), so we need fsnotify_open() here for
* symmetry.
*/
fsnotify_open(file);
}
return ret;
}
struct file *dentry_open(const struct path *path, int flags,
const struct cred *cred)
{
int error;
struct file *f;
/* We must always pass in a valid mount pointer. */
BUG_ON(!path->mnt);
f = alloc_empty_file(flags, cred);
if (!IS_ERR(f)) {
error = vfs_open(path, f);
if (error) {
fput(f);
f = ERR_PTR(error);
}
}
return f;
}
EXPORT_SYMBOL(dentry_open);
/**
* dentry_create - Create and open a file
* @path: path to create
* @flags: O_ flags
* @mode: mode bits for new file
* @cred: credentials to use
*
* Caller must hold the parent directory's lock, and have prepared
* a negative dentry, placed in @path->dentry, for the new file.
*
* Caller sets @path->mnt to the vfsmount of the filesystem where
* the new file is to be created. The parent directory and the
* negative dentry must reside on the same filesystem instance.
*
* On success, returns a "struct file *". Otherwise a ERR_PTR
* is returned.
*/
struct file *dentry_create(const struct path *path, int flags, umode_t mode,
const struct cred *cred)
{
struct file *f;
int error;
f = alloc_empty_file(flags, cred);
if (IS_ERR(f))
return f;
error = vfs_create(mnt_idmap(path->mnt),
d_inode(path->dentry->d_parent),
path->dentry, mode, true);
if (!error)
error = vfs_open(path, f);
if (unlikely(error)) {
fput(f);
return ERR_PTR(error);
}
return f;
}
EXPORT_SYMBOL(dentry_create);
/**
* kernel_file_open - open a file for kernel internal use
* @path: path of the file to open
* @flags: open flags
* @cred: credentials for open
*
* Open a file for use by in-kernel consumers. The file is not accounted
* against nr_files and must not be installed into the file descriptor
* table.
*
* Return: Opened file on success, an error pointer on failure.
*/
struct file *kernel_file_open(const struct path *path, int flags,
const struct cred *cred)
{
struct file *f;
int error;
f = alloc_empty_file_noaccount(flags, cred);
if (IS_ERR(f))
return f;
f->f_path = *path;
error = do_dentry_open(f, NULL);
if (error) {
fput(f);
return ERR_PTR(error);
}
fsnotify_open(f);
return f;
}
EXPORT_SYMBOL_GPL(kernel_file_open);
#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
inline struct open_how build_open_how(int flags, umode_t mode)
{
struct open_how how = {
.flags = flags & VALID_OPEN_FLAGS,
.mode = mode & S_IALLUGO,
};
/* O_PATH beats everything else. */
if (how.flags & O_PATH)
how.flags &= O_PATH_FLAGS;
/* Modes should only be set for create-like flags. */
if (!WILL_CREATE(how.flags))
how.mode = 0;
return how;
}
inline int build_open_flags(const struct open_how *how, struct open_flags *op)
{
u64 flags = how->flags;
u64 strip = __FMODE_NONOTIFY | O_CLOEXEC;
int lookup_flags = 0;
int acc_mode = ACC_MODE(flags);
BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
"struct open_flags doesn't yet handle flags > 32 bits");
/*
* Strip flags that either shouldn't be set by userspace like
* FMODE_NONOTIFY or that aren't relevant in determining struct
* open_flags like O_CLOEXEC.
*/
flags &= ~strip;
/*
* Older syscalls implicitly clear all of the invalid flags or argument
* values before calling build_open_flags(), but openat2(2) checks all
* of its arguments.
*/
if (flags & ~VALID_OPEN_FLAGS)
return -EINVAL;
if (how->resolve & ~VALID_RESOLVE_FLAGS)
return -EINVAL;
/* Scoping flags are mutually exclusive. */
if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
return -EINVAL;
/* Deal with the mode. */
if (WILL_CREATE(flags)) {
if (how->mode & ~S_IALLUGO)
return -EINVAL;
op->mode = how->mode | S_IFREG;
} else {
if (how->mode != 0)
return -EINVAL;
op->mode = 0;
}
/*
* Block bugs where O_DIRECTORY | O_CREAT created regular files.
* Note, that blocking O_DIRECTORY | O_CREAT here also protects
* O_TMPFILE below which requires O_DIRECTORY being raised.
*/
if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT))
return -EINVAL;
/* Now handle the creative implementation of O_TMPFILE. */
if (flags & __O_TMPFILE) {
/*
* In order to ensure programs get explicit errors when trying
* to use O_TMPFILE on old kernels we enforce that O_DIRECTORY
* is raised alongside __O_TMPFILE.
*/
if (!(flags & O_DIRECTORY))
return -EINVAL;
if (!(acc_mode & MAY_WRITE))
return -EINVAL;
}
if (flags & O_PATH) {
/* O_PATH only permits certain other flags to be set. */
if (flags & ~O_PATH_FLAGS)
return -EINVAL;
acc_mode = 0;
}
/*
* O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
* check for O_DSYNC if the need any syncing at all we enforce it's
* always set instead of having to deal with possibly weird behaviour
* for malicious applications setting only __O_SYNC.
*/
if (flags & __O_SYNC)
flags |= O_DSYNC;
op->open_flag = flags;
/* O_TRUNC implies we need access checks for write permissions */
if (flags & O_TRUNC)
acc_mode |= MAY_WRITE;
/* Allow the LSM permission hook to distinguish append
access from general write access. */
if (flags & O_APPEND)
acc_mode |= MAY_APPEND;
op->acc_mode = acc_mode;
op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
if (flags & O_CREAT) {
op->intent |= LOOKUP_CREATE;
if (flags & O_EXCL) {
op->intent |= LOOKUP_EXCL;
flags |= O_NOFOLLOW;
}
}
if (flags & O_DIRECTORY)
lookup_flags |= LOOKUP_DIRECTORY;
if (!(flags & O_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
if (how->resolve & RESOLVE_NO_XDEV)
lookup_flags |= LOOKUP_NO_XDEV;
if (how->resolve & RESOLVE_NO_MAGICLINKS)
lookup_flags |= LOOKUP_NO_MAGICLINKS;
if (how->resolve & RESOLVE_NO_SYMLINKS)
lookup_flags |= LOOKUP_NO_SYMLINKS;
if (how->resolve & RESOLVE_BENEATH)
lookup_flags |= LOOKUP_BENEATH;
if (how->resolve & RESOLVE_IN_ROOT)
lookup_flags |= LOOKUP_IN_ROOT;
if (how->resolve & RESOLVE_CACHED) {
/* Don't bother even trying for create/truncate/tmpfile open */
if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
return -EAGAIN;
lookup_flags |= LOOKUP_CACHED;
}
op->lookup_flags = lookup_flags;
return 0;
}
/**
* file_open_name - open file and return file pointer
*
* @name: struct filename containing path to open
* @flags: open flags as per the open(2) second argument
* @mode: mode for the new file if O_CREAT is set, else ignored
*
* This is the helper to open a file from kernelspace if you really
* have to. But in generally you should not do this, so please move
* along, nothing to see here..
*/
struct file *file_open_name(struct filename *name, int flags, umode_t mode)
{
struct open_flags op;
struct open_how how = build_open_how(flags, mode);
int err = build_open_flags(&how, &op);
if (err)
return ERR_PTR(err);
return do_filp_open(AT_FDCWD, name, &op);
}
/**
* filp_open - open file and return file pointer
*
* @filename: path to open
* @flags: open flags as per the open(2) second argument
* @mode: mode for the new file if O_CREAT is set, else ignored
*
* This is the helper to open a file from kernelspace if you really
* have to. But in generally you should not do this, so please move
* along, nothing to see here..
*/
struct file *filp_open(const char *filename, int flags, umode_t mode)
{
struct filename *name = getname_kernel(filename);
struct file *file = ERR_CAST(name);
if (!IS_ERR(name)) {
file = file_open_name(name, flags, mode);
putname(name);
}
return file;
}
EXPORT_SYMBOL(filp_open);
struct file *file_open_root(const struct path *root,
const char *filename, int flags, umode_t mode)
{
struct open_flags op;
struct open_how how = build_open_how(flags, mode);
int err = build_open_flags(&how, &op);
if (err)
return ERR_PTR(err);
return do_file_open_root(root, filename, &op);
}
EXPORT_SYMBOL(file_open_root);
static long do_sys_openat2(int dfd, const char __user *filename,
struct open_how *how)
{
struct open_flags op;
int fd = build_open_flags(how, &op);
struct filename *tmp;
if (fd)
return fd;
tmp = getname(filename);
if (IS_ERR(tmp))
return PTR_ERR(tmp);
fd = get_unused_fd_flags(how->flags);
if (fd >= 0) {
struct file *f = do_filp_open(dfd, tmp, &op);
if (IS_ERR(f)) {
put_unused_fd(fd);
fd = PTR_ERR(f);
} else {
fd_install(fd, f);
}
}
putname(tmp);
return fd;
}
long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
{
struct open_how how = build_open_how(flags, mode);
return do_sys_openat2(dfd, filename, &how);
}
SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
{
if (force_o_largefile())
flags |= O_LARGEFILE;
return do_sys_open(AT_FDCWD, filename, flags, mode);
}
SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
umode_t, mode)
{
if (force_o_largefile())
flags |= O_LARGEFILE;
return do_sys_open(dfd, filename, flags, mode);
}
SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
struct open_how __user *, how, size_t, usize)
{
int err;
struct open_how tmp;
BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
if (unlikely(usize < OPEN_HOW_SIZE_VER0))
return -EINVAL;
if (unlikely(usize > PAGE_SIZE))
return -E2BIG;
err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
if (err)
return err;
audit_openat2_how(&tmp);
/* O_LARGEFILE is only allowed for non-O_PATH. */
if (!(tmp.flags & O_PATH) && force_o_largefile())
tmp.flags |= O_LARGEFILE;
return do_sys_openat2(dfd, filename, &tmp);
}
#ifdef CONFIG_COMPAT
/*
* Exactly like sys_open(), except that it doesn't set the
* O_LARGEFILE flag.
*/
COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
{
return do_sys_open(AT_FDCWD, filename, flags, mode);
}
/*
* Exactly like sys_openat(), except that it doesn't set the
* O_LARGEFILE flag.
*/
COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
{
return do_sys_open(dfd, filename, flags, mode);
}
#endif
#ifndef __alpha__
/*
* For backward compatibility? Maybe this should be moved
* into arch/i386 instead?
*/
SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
{
int flags = O_CREAT | O_WRONLY | O_TRUNC;
if (force_o_largefile())
flags |= O_LARGEFILE;
return do_sys_open(AT_FDCWD, pathname, flags, mode);
}
#endif
/*
* "id" is the POSIX thread ID. We use the
* files pointer for this..
*/
static int filp_flush(struct file *filp, fl_owner_t id)
{
int retval = 0;
if (CHECK_DATA_CORRUPTION(file_count(filp) == 0,
"VFS: Close: file count is 0 (f_op=%ps)",
filp->f_op)) {
return 0;
}
if (filp->f_op->flush)
retval = filp->f_op->flush(filp, id);
if (likely(!(filp->f_mode & FMODE_PATH))) {
dnotify_flush(filp, id);
locks_remove_posix(filp, id);
}
return retval;
}
int filp_close(struct file *filp, fl_owner_t id)
{
int retval;
retval = filp_flush(filp, id);
fput(filp);
return retval;
}
EXPORT_SYMBOL(filp_close);
/*
* Careful here! We test whether the file pointer is NULL before
* releasing the fd. This ensures that one clone task can't release
* an fd while another clone is opening it.
*/
SYSCALL_DEFINE1(close, unsigned int, fd)
{
int retval;
struct file *file;
file = file_close_fd(fd);
if (!file)
return -EBADF;
retval = filp_flush(file, current->files);
/*
* We're returning to user space. Don't bother
* with any delayed fput() cases.
*/
__fput_sync(file);
/* can't restart close syscall because file table entry was cleared */
if (unlikely(retval == -ERESTARTSYS ||
retval == -ERESTARTNOINTR ||
retval == -ERESTARTNOHAND ||
retval == -ERESTART_RESTARTBLOCK))
retval = -EINTR;
return retval;
}
/**
* sys_close_range() - Close all file descriptors in a given range.
*
* @fd: starting file descriptor to close
* @max_fd: last file descriptor to close
* @flags: reserved for future extensions
*
* This closes a range of file descriptors. All file descriptors
* from @fd up to and including @max_fd are closed.
* Currently, errors to close a given file descriptor are ignored.
*/
SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
unsigned int, flags)
{
return __close_range(fd, max_fd, flags);
}
/*
* This routine simulates a hangup on the tty, to arrange that users
* are given clean terminals at login time.
*/
SYSCALL_DEFINE0(vhangup)
{
if (capable(CAP_SYS_TTY_CONFIG)) {
tty_vhangup_self();
return 0;
}
return -EPERM;
}
/*
* Called when an inode is about to be open.
* We use this to disallow opening large files on 32bit systems if
* the caller didn't specify O_LARGEFILE. On 64bit systems we force
* on this flag in sys_open.
*/
int generic_file_open(struct inode * inode, struct file * filp)
{
if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
return -EOVERFLOW;
return 0;
}
EXPORT_SYMBOL(generic_file_open);
/*
* This is used by subsystems that don't want seekable
* file descriptors. The function is not supposed to ever fail, the only
* reason it returns an 'int' and not 'void' is so that it can be plugged
* directly into file_operations structure.
*/
int nonseekable_open(struct inode *inode, struct file *filp)
{
filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
return 0;
}
EXPORT_SYMBOL(nonseekable_open);
/*
* stream_open is used by subsystems that want stream-like file descriptors.
* Such file descriptors are not seekable and don't have notion of position
* (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
* Contrary to file descriptors of other regular files, .read() and .write()
* can run simultaneously.
*
* stream_open never fails and is marked to return int so that it could be
* directly used as file_operations.open .
*/
int stream_open(struct inode *inode, struct file *filp)
{
filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
filp->f_mode |= FMODE_STREAM;
return 0;
}
EXPORT_SYMBOL(stream_open);