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