![Deepa Dinamani](/assets/img/avatar_default.png)
POSIX is ambiguous on the behavior of timestamps for futimens, utimensat and utimes. Whether to return an error or silently clamp a timestamp beyond the range supported by the underlying filesystems is not clear. POSIX.1 section for futimens, utimensat and utimes says: (http://pubs.opengroup.org/onlinepubs/9699919799/functions/futimens.html) The file's relevant timestamp shall be set to the greatest value supported by the file system that is not greater than the specified time. If the tv_nsec field of a timespec structure has the special value UTIME_NOW, the file's relevant timestamp shall be set to the greatest value supported by the file system that is not greater than the current time. [EINVAL] A new file timestamp would be a value whose tv_sec component is not a value supported by the file system. The patch chooses to clamp the timestamps according to the filesystem timestamp ranges and does not return an error. This is in line with the behavior of utime syscall also since the POSIX page(http://pubs.opengroup.org/onlinepubs/009695399/functions/utime.html) for utime does not mention returning an error or clamping like above. Same for utimes http://pubs.opengroup.org/onlinepubs/009695399/functions/utimes.html Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Acked-by: Jeff Layton <jlayton@kernel.org>
290 lines
7.3 KiB
C
290 lines
7.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/file.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/utime.h>
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#include <linux/syscalls.h>
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#include <linux/uaccess.h>
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#include <linux/compat.h>
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#include <asm/unistd.h>
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static bool nsec_valid(long nsec)
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{
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if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
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return true;
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return nsec >= 0 && nsec <= 999999999;
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}
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static int utimes_common(const struct path *path, struct timespec64 *times)
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{
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int error;
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struct iattr newattrs;
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struct inode *inode = path->dentry->d_inode;
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struct inode *delegated_inode = NULL;
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error = mnt_want_write(path->mnt);
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if (error)
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goto out;
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if (times && times[0].tv_nsec == UTIME_NOW &&
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times[1].tv_nsec == UTIME_NOW)
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times = NULL;
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newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
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if (times) {
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if (times[0].tv_nsec == UTIME_OMIT)
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newattrs.ia_valid &= ~ATTR_ATIME;
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else if (times[0].tv_nsec != UTIME_NOW) {
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newattrs.ia_atime = timestamp_truncate(times[0], inode);
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newattrs.ia_valid |= ATTR_ATIME_SET;
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}
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if (times[1].tv_nsec == UTIME_OMIT)
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newattrs.ia_valid &= ~ATTR_MTIME;
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else if (times[1].tv_nsec != UTIME_NOW) {
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newattrs.ia_mtime = timestamp_truncate(times[1], inode);
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newattrs.ia_valid |= ATTR_MTIME_SET;
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}
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/*
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* Tell setattr_prepare(), that this is an explicit time
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* update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
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* were used.
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*/
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newattrs.ia_valid |= ATTR_TIMES_SET;
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} else {
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newattrs.ia_valid |= ATTR_TOUCH;
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}
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retry_deleg:
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inode_lock(inode);
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error = notify_change(path->dentry, &newattrs, &delegated_inode);
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inode_unlock(inode);
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if (delegated_inode) {
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error = break_deleg_wait(&delegated_inode);
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if (!error)
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goto retry_deleg;
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}
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mnt_drop_write(path->mnt);
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out:
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return error;
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}
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/*
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* do_utimes - change times on filename or file descriptor
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* @dfd: open file descriptor, -1 or AT_FDCWD
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* @filename: path name or NULL
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* @times: new times or NULL
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* @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
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*
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* If filename is NULL and dfd refers to an open file, then operate on
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* the file. Otherwise look up filename, possibly using dfd as a
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* starting point.
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*
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* If times==NULL, set access and modification to current time,
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* must be owner or have write permission.
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* Else, update from *times, must be owner or super user.
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*/
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long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
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int flags)
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{
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int error = -EINVAL;
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if (times && (!nsec_valid(times[0].tv_nsec) ||
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!nsec_valid(times[1].tv_nsec))) {
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goto out;
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}
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if (flags & ~AT_SYMLINK_NOFOLLOW)
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goto out;
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if (filename == NULL && dfd != AT_FDCWD) {
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struct fd f;
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if (flags & AT_SYMLINK_NOFOLLOW)
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goto out;
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f = fdget(dfd);
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error = -EBADF;
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if (!f.file)
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goto out;
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error = utimes_common(&f.file->f_path, times);
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fdput(f);
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} else {
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struct path path;
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int lookup_flags = 0;
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if (!(flags & AT_SYMLINK_NOFOLLOW))
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lookup_flags |= LOOKUP_FOLLOW;
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retry:
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error = user_path_at(dfd, filename, lookup_flags, &path);
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if (error)
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goto out;
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error = utimes_common(&path, times);
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path_put(&path);
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if (retry_estale(error, lookup_flags)) {
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lookup_flags |= LOOKUP_REVAL;
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goto retry;
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}
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}
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out:
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return error;
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}
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SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
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struct __kernel_timespec __user *, utimes, int, flags)
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{
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struct timespec64 tstimes[2];
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if (utimes) {
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if ((get_timespec64(&tstimes[0], &utimes[0]) ||
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get_timespec64(&tstimes[1], &utimes[1])))
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return -EFAULT;
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/* Nothing to do, we must not even check the path. */
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if (tstimes[0].tv_nsec == UTIME_OMIT &&
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tstimes[1].tv_nsec == UTIME_OMIT)
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return 0;
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}
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return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
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}
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#ifdef __ARCH_WANT_SYS_UTIME
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/*
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* futimesat(), utimes() and utime() are older versions of utimensat()
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* that are provided for compatibility with traditional C libraries.
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* On modern architectures, we always use libc wrappers around
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* utimensat() instead.
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*/
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static long do_futimesat(int dfd, const char __user *filename,
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struct timeval __user *utimes)
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{
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struct timeval times[2];
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struct timespec64 tstimes[2];
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if (utimes) {
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if (copy_from_user(×, utimes, sizeof(times)))
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return -EFAULT;
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/* This test is needed to catch all invalid values. If we
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would test only in do_utimes we would miss those invalid
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values truncated by the multiplication with 1000. Note
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that we also catch UTIME_{NOW,OMIT} here which are only
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valid for utimensat. */
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if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
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times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
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return -EINVAL;
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tstimes[0].tv_sec = times[0].tv_sec;
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tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
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tstimes[1].tv_sec = times[1].tv_sec;
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tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
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}
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return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
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}
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SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
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struct timeval __user *, utimes)
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{
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return do_futimesat(dfd, filename, utimes);
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}
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SYSCALL_DEFINE2(utimes, char __user *, filename,
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struct timeval __user *, utimes)
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{
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return do_futimesat(AT_FDCWD, filename, utimes);
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}
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SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
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{
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struct timespec64 tv[2];
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if (times) {
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if (get_user(tv[0].tv_sec, ×->actime) ||
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get_user(tv[1].tv_sec, ×->modtime))
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return -EFAULT;
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tv[0].tv_nsec = 0;
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tv[1].tv_nsec = 0;
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}
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return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
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}
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#endif
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#ifdef CONFIG_COMPAT_32BIT_TIME
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/*
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* Not all architectures have sys_utime, so implement this in terms
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* of sys_utimes.
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*/
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#ifdef __ARCH_WANT_SYS_UTIME32
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SYSCALL_DEFINE2(utime32, const char __user *, filename,
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struct old_utimbuf32 __user *, t)
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{
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struct timespec64 tv[2];
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if (t) {
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if (get_user(tv[0].tv_sec, &t->actime) ||
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get_user(tv[1].tv_sec, &t->modtime))
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return -EFAULT;
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tv[0].tv_nsec = 0;
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tv[1].tv_nsec = 0;
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}
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return do_utimes(AT_FDCWD, filename, t ? tv : NULL, 0);
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}
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#endif
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SYSCALL_DEFINE4(utimensat_time32, unsigned int, dfd, const char __user *, filename, struct old_timespec32 __user *, t, int, flags)
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{
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struct timespec64 tv[2];
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if (t) {
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if (get_old_timespec32(&tv[0], &t[0]) ||
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get_old_timespec32(&tv[1], &t[1]))
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return -EFAULT;
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if (tv[0].tv_nsec == UTIME_OMIT && tv[1].tv_nsec == UTIME_OMIT)
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return 0;
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}
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return do_utimes(dfd, filename, t ? tv : NULL, flags);
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}
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#ifdef __ARCH_WANT_SYS_UTIME32
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static long do_compat_futimesat(unsigned int dfd, const char __user *filename,
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struct old_timeval32 __user *t)
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{
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struct timespec64 tv[2];
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if (t) {
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if (get_user(tv[0].tv_sec, &t[0].tv_sec) ||
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get_user(tv[0].tv_nsec, &t[0].tv_usec) ||
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get_user(tv[1].tv_sec, &t[1].tv_sec) ||
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get_user(tv[1].tv_nsec, &t[1].tv_usec))
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return -EFAULT;
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if (tv[0].tv_nsec >= 1000000 || tv[0].tv_nsec < 0 ||
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tv[1].tv_nsec >= 1000000 || tv[1].tv_nsec < 0)
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return -EINVAL;
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tv[0].tv_nsec *= 1000;
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tv[1].tv_nsec *= 1000;
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}
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return do_utimes(dfd, filename, t ? tv : NULL, 0);
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}
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SYSCALL_DEFINE3(futimesat_time32, unsigned int, dfd,
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const char __user *, filename,
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struct old_timeval32 __user *, t)
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{
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return do_compat_futimesat(dfd, filename, t);
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}
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SYSCALL_DEFINE2(utimes_time32, const char __user *, filename, struct old_timeval32 __user *, t)
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{
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return do_compat_futimesat(AT_FDCWD, filename, t);
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}
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#endif
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#endif
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