fs/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
  11 #ifdef __ARCH_WANT_SYS_UTIME
  12
  13 /*
  14  * sys_utime() can be implemented in user-level using sys_utimes().
  15  * Is this for backwards compatibility?  If so, why not move it
  16  * into the appropriate arch directory (for those architectures that
  17  * need it).
  18  */
  19
  20 /* If times==NULL, set access and modification to current time,
  21  * must be owner or have write permission.
  22  * Else, update from *times, must be owner or super user.
  23  */
  24 SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
  25 {
  26         struct timespec64 tv[2];
  27
  28         if (times) {
  29                 if (get_user(tv[0].tv_sec, &times->actime) ||
  30                     get_user(tv[1].tv_sec, &times->modtime))
  31                         return -EFAULT;
  32                 tv[0].tv_nsec = 0;
  33                 tv[1].tv_nsec = 0;
  34         }
  35         return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
  36 }
  37
  38 #endif
  39
  40 static bool nsec_valid(long nsec)
  41 {
  42         if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
  43                 return true;
  44
  45         return nsec >= 0 && nsec <= 999999999;
  46 }
  47
  48 static int utimes_common(const struct path *path, struct timespec64 *times)
  49 {
  50         int error;
  51         struct iattr newattrs;
  52         struct inode *inode = path->dentry->d_inode;
  53         struct inode *delegated_inode = NULL;
  54
  55         error = mnt_want_write(path->mnt);
  56         if (error)
  57                 goto out;
  58
  59         if (times && times[0].tv_nsec == UTIME_NOW &&
  60                      times[1].tv_nsec == UTIME_NOW)
  61                 times = NULL;
  62
  63         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
  64         if (times) {
  65                 if (times[0].tv_nsec == UTIME_OMIT)
  66                         newattrs.ia_valid &= ~ATTR_ATIME;
  67                 else if (times[0].tv_nsec != UTIME_NOW) {
  68                         newattrs.ia_atime.tv_sec = times[0].tv_sec;
  69                         newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
  70                         newattrs.ia_valid |= ATTR_ATIME_SET;
  71                 }
  72
  73                 if (times[1].tv_nsec == UTIME_OMIT)
  74                         newattrs.ia_valid &= ~ATTR_MTIME;
  75                 else if (times[1].tv_nsec != UTIME_NOW) {
  76                         newattrs.ia_mtime.tv_sec = times[1].tv_sec;
  77                         newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
  78                         newattrs.ia_valid |= ATTR_MTIME_SET;
  79                 }
  80                 /*
  81                  * Tell setattr_prepare(), that this is an explicit time
  82                  * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
  83                  * were used.
  84                  */
  85                 newattrs.ia_valid |= ATTR_TIMES_SET;
  86         } else {
  87                 newattrs.ia_valid |= ATTR_TOUCH;
  88         }
  89 retry_deleg:
  90         inode_lock(inode);
  91         error = notify_change(path->dentry, &newattrs, &delegated_inode);
  92         inode_unlock(inode);
  93         if (delegated_inode) {
  94                 error = break_deleg_wait(&delegated_inode);
  95                 if (!error)
  96                         goto retry_deleg;
  97         }
  98
  99         mnt_drop_write(path->mnt);
 100 out:
 101         return error;
 102 }
 103
 104 /*
 105  * do_utimes - change times on filename or file descriptor
 106  * @dfd: open file descriptor, -1 or AT_FDCWD
 107  * @filename: path name or NULL
 108  * @times: new times or NULL
 109  * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
 110  *
 111  * If filename is NULL and dfd refers to an open file, then operate on
 112  * the file.  Otherwise look up filename, possibly using dfd as a
 113  * starting point.
 114  *
 115  * If times==NULL, set access and modification to current time,
 116  * must be owner or have write permission.
 117  * Else, update from *times, must be owner or super user.
 118  */
 119 long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
 120                int flags)
 121 {
 122         int error = -EINVAL;
 123
 124         if (times && (!nsec_valid(times[0].tv_nsec) ||
 125                       !nsec_valid(times[1].tv_nsec))) {
 126                 goto out;
 127         }
 128
 129         if (flags & ~AT_SYMLINK_NOFOLLOW)
 130                 goto out;
 131
 132         if (filename == NULL && dfd != AT_FDCWD) {
 133                 struct fd f;
 134
 135                 if (flags & AT_SYMLINK_NOFOLLOW)
 136                         goto out;
 137
 138                 f = fdget(dfd);
 139                 error = -EBADF;
 140                 if (!f.file)
 141                         goto out;
 142
 143                 error = utimes_common(&f.file->f_path, times);
 144                 fdput(f);
 145         } else {
 146                 struct path path;
 147                 int lookup_flags = 0;
 148
 149                 if (!(flags & AT_SYMLINK_NOFOLLOW))
 150                         lookup_flags |= LOOKUP_FOLLOW;
 151 retry:
 152                 error = user_path_at(dfd, filename, lookup_flags, &path);
 153                 if (error)
 154                         goto out;
 155
 156                 error = utimes_common(&path, times);
 157                 path_put(&path);
 158                 if (retry_estale(error, lookup_flags)) {
 159                         lookup_flags |= LOOKUP_REVAL;
 160                         goto retry;
 161                 }
 162         }
 163
 164 out:
 165         return error;
 166 }
 167
 168 SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
 169                 struct timespec __user *, utimes, int, flags)
 170 {
 171         struct timespec64 tstimes[2];
 172
 173         if (utimes) {
 174                 if ((get_timespec64(&tstimes[0], &utimes[0]) ||
 175                         get_timespec64(&tstimes[1], &utimes[1])))
 176                         return -EFAULT;
 177
 178                 /* Nothing to do, we must not even check the path.  */
 179                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
 180                     tstimes[1].tv_nsec == UTIME_OMIT)
 181                         return 0;
 182         }
 183
 184         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
 185 }
 186
 187 static long do_futimesat(int dfd, const char __user *filename,
 188                          struct timeval __user *utimes)
 189 {
 190         struct timeval times[2];
 191         struct timespec64 tstimes[2];
 192
 193         if (utimes) {
 194                 if (copy_from_user(&times, utimes, sizeof(times)))
 195                         return -EFAULT;
 196
 197                 /* This test is needed to catch all invalid values.  If we
 198                    would test only in do_utimes we would miss those invalid
 199                    values truncated by the multiplication with 1000.  Note
 200                    that we also catch UTIME_{NOW,OMIT} here which are only
 201                    valid for utimensat.  */
 202                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
 203                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
 204                         return -EINVAL;
 205
 206                 tstimes[0].tv_sec = times[0].tv_sec;
 207                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
 208                 tstimes[1].tv_sec = times[1].tv_sec;
 209                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
 210         }
 211
 212         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
 213 }
 214
 215
 216 SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
 217                 struct timeval __user *, utimes)
 218 {
 219         return do_futimesat(dfd, filename, utimes);
 220 }
 221
 222 SYSCALL_DEFINE2(utimes, char __user *, filename,
 223                 struct timeval __user *, utimes)
 224 {
 225         return do_futimesat(AT_FDCWD, filename, utimes);
 226 }
 227
 228 #ifdef CONFIG_COMPAT
 229 /*
 230  * Not all architectures have sys_utime, so implement this in terms
 231  * of sys_utimes.
 232  */
 233 COMPAT_SYSCALL_DEFINE2(utime, const char __user *, filename,
 234                        struct compat_utimbuf __user *, t)
 235 {
 236         struct timespec64 tv[2];
 237
 238         if (t) {
 239                 if (get_user(tv[0].tv_sec, &t->actime) ||
 240                     get_user(tv[1].tv_sec, &t->modtime))
 241                         return -EFAULT;
 242                 tv[0].tv_nsec = 0;
 243                 tv[1].tv_nsec = 0;
 244         }
 245         return do_utimes(AT_FDCWD, filename, t ? tv : NULL, 0);
 246 }
 247
 248 COMPAT_SYSCALL_DEFINE4(utimensat, unsigned int, dfd, const char __user *, filename, struct compat_timespec __user *, t, int, flags)
 249 {
 250         struct timespec64 tv[2];
 251
 252         if  (t) {
 253                 if (compat_get_timespec64(&tv[0], &t[0]) ||
 254                     compat_get_timespec64(&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 static long do_compat_futimesat(unsigned int dfd, const char __user *filename,
 264                                 struct compat_timeval __user *t)
 265 {
 266         struct timespec64 tv[2];
 267
 268         if (t) {
 269                 if (get_user(tv[0].tv_sec, &t[0].tv_sec) ||
 270                     get_user(tv[0].tv_nsec, &t[0].tv_usec) ||
 271                     get_user(tv[1].tv_sec, &t[1].tv_sec) ||
 272                     get_user(tv[1].tv_nsec, &t[1].tv_usec))
 273                         return -EFAULT;
 274                 if (tv[0].tv_nsec >= 1000000 || tv[0].tv_nsec < 0 ||
 275                     tv[1].tv_nsec >= 1000000 || tv[1].tv_nsec < 0)
 276                         return -EINVAL;
 277                 tv[0].tv_nsec *= 1000;
 278                 tv[1].tv_nsec *= 1000;
 279         }
 280         return do_utimes(dfd, filename, t ? tv : NULL, 0);
 281 }
 282
 283 COMPAT_SYSCALL_DEFINE3(futimesat, unsigned int, dfd,
 284                        const char __user *, filename,
 285                        struct compat_timeval __user *, t)
 286 {
 287         return do_compat_futimesat(dfd, filename, t);
 288 }
 289
 290 COMPAT_SYSCALL_DEFINE2(utimes, const char __user *, filename, struct compat_timeval __user *, t)
 291 {
 292         return do_compat_futimesat(AT_FDCWD, filename, t);
 293 }
 294 #endif