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