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 #include <linux/filelock.h>
  11
  12 static 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
  20 int 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 inode *delegated_inode = NULL;
  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         }
  64 retry_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 (delegated_inode) {
  70                 error = break_deleg_wait(&delegated_inode);
  71                 if (!error)
  72                         goto retry_deleg;
  73         }
  74
  75         mnt_drop_write(path->mnt);
  76 out:
  77         return error;
  78 }
  79
  80 static int do_utimes_path(int dfd, const char __user *filename,
  81                 struct timespec64 *times, int flags)
  82 {
  83         struct path path;
  84         int lookup_flags = 0, error;
  85
  86         if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
  87                 return -EINVAL;
  88
  89         if (!(flags & AT_SYMLINK_NOFOLLOW))
  90                 lookup_flags |= LOOKUP_FOLLOW;
  91         if (flags & AT_EMPTY_PATH)
  92                 lookup_flags |= LOOKUP_EMPTY;
  93
  94 retry:
  95         error = user_path_at(dfd, filename, lookup_flags, &path);
  96         if (error)
  97                 return error;
  98
  99         error = vfs_utimes(&path, times);
 100         path_put(&path);
 101         if (retry_estale(error, lookup_flags)) {
 102                 lookup_flags |= LOOKUP_REVAL;
 103                 goto retry;
 104         }
 105
 106         return error;
 107 }
 108
 109 static int do_utimes_fd(int fd, struct timespec64 *times, int flags)
 110 {
 111         struct fd f;
 112         int error;
 113
 114         if (flags)
 115                 return -EINVAL;
 116
 117         f = fdget(fd);
 118         if (!fd_file(f))
 119                 return -EBADF;
 120         error = vfs_utimes(&fd_file(f)->f_path, times);
 121         fdput(f);
 122         return error;
 123 }
 124
 125 /*
 126  * do_utimes - change times on filename or file descriptor
 127  * @dfd: open file descriptor, -1 or AT_FDCWD
 128  * @filename: path name or NULL
 129  * @times: new times or NULL
 130  * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
 131  *
 132  * If filename is NULL and dfd refers to an open file, then operate on
 133  * the file.  Otherwise look up filename, possibly using dfd as a
 134  * starting point.
 135  *
 136  * If times==NULL, set access and modification to current time,
 137  * must be owner or have write permission.
 138  * Else, update from *times, must be owner or super user.
 139  */
 140 long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
 141                int flags)
 142 {
 143         if (filename == NULL && dfd != AT_FDCWD)
 144                 return do_utimes_fd(dfd, times, flags);
 145         return do_utimes_path(dfd, filename, times, flags);
 146 }
 147
 148 SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
 149                 struct __kernel_timespec __user *, utimes, int, flags)
 150 {
 151         struct timespec64 tstimes[2];
 152
 153         if (utimes) {
 154                 if ((get_timespec64(&tstimes[0], &utimes[0]) ||
 155                         get_timespec64(&tstimes[1], &utimes[1])))
 156                         return -EFAULT;
 157
 158                 /* Nothing to do, we must not even check the path.  */
 159                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
 160                     tstimes[1].tv_nsec == UTIME_OMIT)
 161                         return 0;
 162         }
 163
 164         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
 165 }
 166
 167 #ifdef __ARCH_WANT_SYS_UTIME
 168 /*
 169  * futimesat(), utimes() and utime() are older versions of utimensat()
 170  * that are provided for compatibility with traditional C libraries.
 171  * On modern architectures, we always use libc wrappers around
 172  * utimensat() instead.
 173  */
 174 static long do_futimesat(int dfd, const char __user *filename,
 175                          struct __kernel_old_timeval __user *utimes)
 176 {
 177         struct __kernel_old_timeval times[2];
 178         struct timespec64 tstimes[2];
 179
 180         if (utimes) {
 181                 if (copy_from_user(&times, utimes, sizeof(times)))
 182                         return -EFAULT;
 183
 184                 /* This test is needed to catch all invalid values.  If we
 185                    would test only in do_utimes we would miss those invalid
 186                    values truncated by the multiplication with 1000.  Note
 187                    that we also catch UTIME_{NOW,OMIT} here which are only
 188                    valid for utimensat.  */
 189                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
 190                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
 191                         return -EINVAL;
 192
 193                 tstimes[0].tv_sec = times[0].tv_sec;
 194                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
 195                 tstimes[1].tv_sec = times[1].tv_sec;
 196                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
 197         }
 198
 199         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
 200 }
 201
 202
 203 SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
 204                 struct __kernel_old_timeval __user *, utimes)
 205 {
 206         return do_futimesat(dfd, filename, utimes);
 207 }
 208
 209 SYSCALL_DEFINE2(utimes, char __user *, filename,
 210                 struct __kernel_old_timeval __user *, utimes)
 211 {
 212         return do_futimesat(AT_FDCWD, filename, utimes);
 213 }
 214
 215 SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
 216 {
 217         struct timespec64 tv[2];
 218
 219         if (times) {
 220                 if (get_user(tv[0].tv_sec, &times->actime) ||
 221                     get_user(tv[1].tv_sec, &times->modtime))
 222                         return -EFAULT;
 223                 tv[0].tv_nsec = 0;
 224                 tv[1].tv_nsec = 0;
 225         }
 226         return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
 227 }
 228 #endif
 229
 230 #ifdef CONFIG_COMPAT_32BIT_TIME
 231 /*
 232  * Not all architectures have sys_utime, so implement this in terms
 233  * of sys_utimes.
 234  */
 235 #ifdef __ARCH_WANT_SYS_UTIME32
 236 SYSCALL_DEFINE2(utime32, const char __user *, filename,
 237                 struct old_utimbuf32 __user *, t)
 238 {
 239         struct timespec64 tv[2];
 240
 241         if (t) {
 242                 if (get_user(tv[0].tv_sec, &t->actime) ||
 243                     get_user(tv[1].tv_sec, &t->modtime))
 244                         return -EFAULT;
 245                 tv[0].tv_nsec = 0;
 246                 tv[1].tv_nsec = 0;
 247         }
 248         return do_utimes(AT_FDCWD, filename, t ? tv : NULL, 0);
 249 }
 250 #endif
 251
 252 SYSCALL_DEFINE4(utimensat_time32, unsigned int, dfd, const char __user *, filename, struct old_timespec32 __user *, t, int, flags)
 253 {
 254         struct timespec64 tv[2];
 255
 256         if  (t) {
 257                 if (get_old_timespec32(&tv[0], &t[0]) ||
 258                     get_old_timespec32(&tv[1], &t[1]))
 259                         return -EFAULT;
 260
 261                 if (tv[0].tv_nsec == UTIME_OMIT && tv[1].tv_nsec == UTIME_OMIT)
 262                         return 0;
 263         }
 264         return do_utimes(dfd, filename, t ? tv : NULL, flags);
 265 }
 266
 267 #ifdef __ARCH_WANT_SYS_UTIME32
 268 static long do_compat_futimesat(unsigned int dfd, const char __user *filename,
 269                                 struct old_timeval32 __user *t)
 270 {
 271         struct timespec64 tv[2];
 272
 273         if (t) {
 274                 if (get_user(tv[0].tv_sec, &t[0].tv_sec) ||
 275                     get_user(tv[0].tv_nsec, &t[0].tv_usec) ||
 276                     get_user(tv[1].tv_sec, &t[1].tv_sec) ||
 277                     get_user(tv[1].tv_nsec, &t[1].tv_usec))
 278                         return -EFAULT;
 279                 if (tv[0].tv_nsec >= 1000000 || tv[0].tv_nsec < 0 ||
 280                     tv[1].tv_nsec >= 1000000 || tv[1].tv_nsec < 0)
 281                         return -EINVAL;
 282                 tv[0].tv_nsec *= 1000;
 283                 tv[1].tv_nsec *= 1000;
 284         }
 285         return do_utimes(dfd, filename, t ? tv : NULL, 0);
 286 }
 287
 288 SYSCALL_DEFINE3(futimesat_time32, unsigned int, dfd,
 289                        const char __user *, filename,
 290                        struct old_timeval32 __user *, t)
 291 {
 292         return do_compat_futimesat(dfd, filename, t);
 293 }
 294
 295 SYSCALL_DEFINE2(utimes_time32, const char __user *, filename, struct old_timeval32 __user *, t)
 296 {
 297         return do_compat_futimesat(AT_FDCWD, filename, t);
 298 }
 299 #endif
 300 #endif