utimes.c

  1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/file.h>
  3#include <linux/mount.h>
  4#include <linux/namei.h>
  5#include <linux/utime.h>
  6#include <linux/syscalls.h>
  7#include <linux/uaccess.h>
  8#include <linux/compat.h>
  9#include <asm/unistd.h>
 10#include <linux/filelock.h>
 11
 12static bool nsec_valid(long nsec)
 13{
 14	if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
 15		return true;
 16
 17	return nsec >= 0 && nsec <= 999999999;
 18}
 19
 20int vfs_utimes(const struct path *path, struct timespec64 *times)
 21{
 22	int error;
 23	struct iattr newattrs;
 24	struct inode *inode = path->dentry->d_inode;
 25	struct delegated_inode delegated_inode = { };
 26
 27	if (times) {
 28		if (!nsec_valid(times[0].tv_nsec) ||
 29		    !nsec_valid(times[1].tv_nsec))
 30			return -EINVAL;
 31		if (times[0].tv_nsec == UTIME_NOW &&
 32		    times[1].tv_nsec == UTIME_NOW)
 33			times = NULL;
 34	}
 35
 36	error = mnt_want_write(path->mnt);
 37	if (error)
 38		goto out;
 39
 40	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 41	if (times) {
 42		if (times[0].tv_nsec == UTIME_OMIT)
 43			newattrs.ia_valid &= ~ATTR_ATIME;
 44		else if (times[0].tv_nsec != UTIME_NOW) {
 45			newattrs.ia_atime = times[0];
 46			newattrs.ia_valid |= ATTR_ATIME_SET;
 47		}
 48
 49		if (times[1].tv_nsec == UTIME_OMIT)
 50			newattrs.ia_valid &= ~ATTR_MTIME;
 51		else if (times[1].tv_nsec != UTIME_NOW) {
 52			newattrs.ia_mtime = times[1];
 53			newattrs.ia_valid |= ATTR_MTIME_SET;
 54		}
 55		/*
 56		 * Tell setattr_prepare(), that this is an explicit time
 57		 * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
 58		 * were used.
 59		 */
 60		newattrs.ia_valid |= ATTR_TIMES_SET;
 61	} else {
 62		newattrs.ia_valid |= ATTR_TOUCH;
 63	}
 64retry_deleg:
 65	inode_lock(inode);
 66	error = notify_change(mnt_idmap(path->mnt), path->dentry, &newattrs,
 67			      &delegated_inode);
 68	inode_unlock(inode);
 69	if (is_delegated(&delegated_inode)) {
 70		error = break_deleg_wait(&delegated_inode);
 71		if (!error)
 72			goto retry_deleg;
 73	}
 74
 75	mnt_drop_write(path->mnt);
 76out:
 77	return error;
 78}
 79EXPORT_SYMBOL_GPL(vfs_utimes);
 80
 81static int do_utimes_path(int dfd, const char __user *filename,
 82		struct timespec64 *times, int flags)
 83{
 84	struct path path;
 85	int lookup_flags = 0, error;
 86
 87	if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
 88		return -EINVAL;
 89
 90	if (!(flags & AT_SYMLINK_NOFOLLOW))
 91		lookup_flags |= LOOKUP_FOLLOW;
 92	if (flags & AT_EMPTY_PATH)
 93		lookup_flags |= LOOKUP_EMPTY;
 94
 95retry:
 96	error = user_path_at(dfd, filename, lookup_flags, &path);
 97	if (error)
 98		return error;
 99
100	error = vfs_utimes(&path, times);
101	path_put(&path);
102	if (retry_estale(error, lookup_flags)) {
103		lookup_flags |= LOOKUP_REVAL;
104		goto retry;
105	}
106
107	return error;
108}
109
110static int do_utimes_fd(int fd, struct timespec64 *times, int flags)
111{
112	if (flags)
113		return -EINVAL;
114
115	CLASS(fd, f)(fd);
116	if (fd_empty(f))
117		return -EBADF;
118	return vfs_utimes(&fd_file(f)->f_path, times);
119}
120
121/*
122 * do_utimes - change times on filename or file descriptor
123 * @dfd: open file descriptor, -1 or AT_FDCWD
124 * @filename: path name or NULL
125 * @times: new times or NULL
126 * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
127 *
128 * If filename is NULL and dfd refers to an open file, then operate on
129 * the file.  Otherwise look up filename, possibly using dfd as a
130 * starting point.
131 *
132 * If times==NULL, set access and modification to current time,
133 * must be owner or have write permission.
134 * Else, update from *times, must be owner or super user.
135 */
136long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
137	       int flags)
138{
139	if (filename == NULL && dfd != AT_FDCWD)
140		return do_utimes_fd(dfd, times, flags);
141	return do_utimes_path(dfd, filename, times, flags);
142}
143
144SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
145		struct __kernel_timespec __user *, utimes, int, flags)
146{
147	struct timespec64 tstimes[2];
148
149	if (utimes) {
150		if ((get_timespec64(&tstimes[0], &utimes[0]) ||
151			get_timespec64(&tstimes[1], &utimes[1])))
152			return -EFAULT;
153
154		/* Nothing to do, we must not even check the path.  */
155		if (tstimes[0].tv_nsec == UTIME_OMIT &&
156		    tstimes[1].tv_nsec == UTIME_OMIT)
157			return 0;
158	}
159
160	return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
161}
162
163#ifdef __ARCH_WANT_SYS_UTIME
164/*
165 * futimesat(), utimes() and utime() are older versions of utimensat()
166 * that are provided for compatibility with traditional C libraries.
167 * On modern architectures, we always use libc wrappers around
168 * utimensat() instead.
169 */
170static long do_futimesat(int dfd, const char __user *filename,
171			 struct __kernel_old_timeval __user *utimes)
172{
173	struct __kernel_old_timeval times[2];
174	struct timespec64 tstimes[2];
175
176	if (utimes) {
177		if (copy_from_user(&times, utimes, sizeof(times)))
178			return -EFAULT;
179
180		/* This test is needed to catch all invalid values.  If we
181		   would test only in do_utimes we would miss those invalid
182		   values truncated by the multiplication with 1000.  Note
183		   that we also catch UTIME_{NOW,OMIT} here which are only
184		   valid for utimensat.  */
185		if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
186		    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
187			return -EINVAL;
188
189		tstimes[0].tv_sec = times[0].tv_sec;
190		tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
191		tstimes[1].tv_sec = times[1].tv_sec;
192		tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
193	}
194
195	return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
196}
197
198
199SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
200		struct __kernel_old_timeval __user *, utimes)
201{
202	return do_futimesat(dfd, filename, utimes);
203}
204
205SYSCALL_DEFINE2(utimes, char __user *, filename,
206		struct __kernel_old_timeval __user *, utimes)
207{
208	return do_futimesat(AT_FDCWD, filename, utimes);
209}
210
211SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
212{
213	struct timespec64 tv[2];
214
215	if (times) {
216		if (get_user(tv[0].tv_sec, &times->actime) ||
217		    get_user(tv[1].tv_sec, &times->modtime))
218			return -EFAULT;
219		tv[0].tv_nsec = 0;
220		tv[1].tv_nsec = 0;
221	}
222	return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
223}
224#endif
225
226#ifdef CONFIG_COMPAT_32BIT_TIME
227/*
228 * Not all architectures have sys_utime, so implement this in terms
229 * of sys_utimes.
230 */
231#ifdef __ARCH_WANT_SYS_UTIME32
232SYSCALL_DEFINE2(utime32, const char __user *, filename,
233		struct old_utimbuf32 __user *, t)
234{
235	struct timespec64 tv[2];
236
237	if (t) {
238		if (get_user(tv[0].tv_sec, &t->actime) ||
239		    get_user(tv[1].tv_sec, &t->modtime))
240			return -EFAULT;
241		tv[0].tv_nsec = 0;
242		tv[1].tv_nsec = 0;
243	}
244	return do_utimes(AT_FDCWD, filename, t ? tv : NULL, 0);
245}
246#endif
247
248SYSCALL_DEFINE4(utimensat_time32, unsigned int, dfd, const char __user *, filename, struct old_timespec32 __user *, t, int, flags)
249{
250	struct timespec64 tv[2];
251
252	if  (t) {
253		if (get_old_timespec32(&tv[0], &t[0]) ||
254		    get_old_timespec32(&tv[1], &t[1]))
255			return -EFAULT;
256
257		if (tv[0].tv_nsec == UTIME_OMIT && tv[1].tv_nsec == UTIME_OMIT)
258			return 0;
259	}
260	return do_utimes(dfd, filename, t ? tv : NULL, flags);
261}
262
263#ifdef __ARCH_WANT_SYS_UTIME32
264static long do_compat_futimesat(unsigned int dfd, const char __user *filename,
265				struct old_timeval32 __user *t)
266{
267	struct timespec64 tv[2];
268
269	if (t) {
270		if (get_user(tv[0].tv_sec, &t[0].tv_sec) ||
271		    get_user(tv[0].tv_nsec, &t[0].tv_usec) ||
272		    get_user(tv[1].tv_sec, &t[1].tv_sec) ||
273		    get_user(tv[1].tv_nsec, &t[1].tv_usec))
274			return -EFAULT;
275		if (tv[0].tv_nsec >= 1000000 || tv[0].tv_nsec < 0 ||
276		    tv[1].tv_nsec >= 1000000 || tv[1].tv_nsec < 0)
277			return -EINVAL;
278		tv[0].tv_nsec *= 1000;
279		tv[1].tv_nsec *= 1000;
280	}
281	return do_utimes(dfd, filename, t ? tv : NULL, 0);
282}
283
284SYSCALL_DEFINE3(futimesat_time32, unsigned int, dfd,
285		       const char __user *, filename,
286		       struct old_timeval32 __user *, t)
287{
288	return do_compat_futimesat(dfd, filename, t);
289}
290
291SYSCALL_DEFINE2(utimes_time32, const char __user *, filename, struct old_timeval32 __user *, t)
292{
293	return do_compat_futimesat(AT_FDCWD, filename, t);
294}
295#endif
296#endif