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 int vfs_utimes(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         if (times) {
  27                 if (!nsec_valid(times[0].tv_nsec) ||
  28                     !nsec_valid(times[1].tv_nsec))
  29                         return -EINVAL;
  30                 if (times[0].tv_nsec == UTIME_NOW &&
  31                     times[1].tv_nsec == UTIME_NOW)
  32                         times = NULL;
  33         }
  34
  35         error = mnt_want_write(path->mnt);
  36         if (error)
  37                 goto out;
  38
  39         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
  40         if (times) {
  41                 if (times[0].tv_nsec == UTIME_OMIT)
  42                         newattrs.ia_valid &= ~ATTR_ATIME;
  43                 else if (times[0].tv_nsec != UTIME_NOW) {
  44                         newattrs.ia_atime = times[0];
  45                         newattrs.ia_valid |= ATTR_ATIME_SET;
  46                 }
  47
  48                 if (times[1].tv_nsec == UTIME_OMIT)
  49                         newattrs.ia_valid &= ~ATTR_MTIME;
  50                 else if (times[1].tv_nsec != UTIME_NOW) {
  51                         newattrs.ia_mtime = times[1];
  52                         newattrs.ia_valid |= ATTR_MTIME_SET;
  53                 }
  54                 /*
  55                  * Tell setattr_prepare(), that this is an explicit time
  56                  * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
  57                  * were used.
  58                  */
  59                 newattrs.ia_valid |= ATTR_TIMES_SET;
  60         } else {
  61                 newattrs.ia_valid |= ATTR_TOUCH;
  62         }
  63 retry_deleg:
  64         inode_lock(inode);
  65         error = notify_change(mnt_user_ns(path->mnt), path->dentry, &newattrs,
  66                               &delegated_inode);
  67         inode_unlock(inode);
  68         if (delegated_inode) {
  69                 error = break_deleg_wait(&delegated_inode);
  70                 if (!error)
  71                         goto retry_deleg;
  72         }
  73
  74         mnt_drop_write(path->mnt);
  75 out:
  76         return error;
  77 }
  78
  79 static int do_utimes_path(int dfd, const char __user *filename,
  80                 struct timespec64 *times, int flags)
  81 {
  82         struct path path;
  83         int lookup_flags = 0, error;
  84
  85         if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
  86                 return -EINVAL;
  87
  88         if (!(flags & AT_SYMLINK_NOFOLLOW))
  89                 lookup_flags |= LOOKUP_FOLLOW;
  90         if (flags & AT_EMPTY_PATH)
  91                 lookup_flags |= LOOKUP_EMPTY;
  92
  93 retry:
  94         error = user_path_at(dfd, filename, lookup_flags, &path);
  95         if (error)
  96                 return error;
  97
  98         error = vfs_utimes(&path, times);
  99         path_put(&path);
 100         if (retry_estale(error, lookup_flags)) {
 101                 lookup_flags |= LOOKUP_REVAL;
 102                 goto retry;
 103         }
 104
 105         return error;
 106 }
 107
 108 static int do_utimes_fd(int fd, struct timespec64 *times, int flags)
 109 {
 110         struct fd f;
 111         int error;
 112
 113         if (flags)
 114                 return -EINVAL;
 115
 116         f = fdget(fd);
 117         if (!f.file)
 118                 return -EBADF;
 119         error = vfs_utimes(&f.file->f_path, times);
 120         fdput(f);
 121         return error;
 122 }
 123
 124 /*
 125  * do_utimes - change times on filename or file descriptor
 126  * @dfd: open file descriptor, -1 or AT_FDCWD
 127  * @filename: path name or NULL
 128  * @times: new times or NULL
 129  * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
 130  *
 131  * If filename is NULL and dfd refers to an open file, then operate on
 132  * the file.  Otherwise look up filename, possibly using dfd as a
 133  * starting point.
 134  *
 135  * If times==NULL, set access and modification to current time,
 136  * must be owner or have write permission.
 137  * Else, update from *times, must be owner or super user.
 138  */
 139 long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
 140                int flags)
 141 {
 142         if (filename == NULL && dfd != AT_FDCWD)
 143                 return do_utimes_fd(dfd, times, flags);
 144         return do_utimes_path(dfd, filename, times, flags);
 145 }
 146
 147 SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
 148                 struct __kernel_timespec __user *, utimes, int, flags)
 149 {
 150         struct timespec64 tstimes[2];
 151
 152         if (utimes) {
 153                 if ((get_timespec64(&tstimes[0], &utimes[0]) ||
 154                         get_timespec64(&tstimes[1], &utimes[1])))
 155                         return -EFAULT;
 156
 157                 /* Nothing to do, we must not even check the path.  */
 158                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
 159                     tstimes[1].tv_nsec == UTIME_OMIT)
 160                         return 0;
 161         }
 162
 163         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
 164 }
 165
 166 #ifdef __ARCH_WANT_SYS_UTIME
 167 /*
 168  * futimesat(), utimes() and utime() are older versions of utimensat()
 169  * that are provided for compatibility with traditional C libraries.
 170  * On modern architectures, we always use libc wrappers around
 171  * utimensat() instead.
 172  */
 173 static long do_futimesat(int dfd, const char __user *filename,
 174                          struct __kernel_old_timeval __user *utimes)
 175 {
 176         struct __kernel_old_timeval times[2];
 177         struct timespec64 tstimes[2];
 178
 179         if (utimes) {
 180                 if (copy_from_user(&times, utimes, sizeof(times)))
 181                         return -EFAULT;
 182
 183                 /* This test is needed to catch all invalid values.  If we
 184                    would test only in do_utimes we would miss those invalid
 185                    values truncated by the multiplication with 1000.  Note
 186                    that we also catch UTIME_{NOW,OMIT} here which are only
 187                    valid for utimensat.  */
 188                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
 189                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
 190                         return -EINVAL;
 191
 192                 tstimes[0].tv_sec = times[0].tv_sec;
 193                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
 194                 tstimes[1].tv_sec = times[1].tv_sec;
 195                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
 196         }
 197
 198         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
 199 }
 200
 201
 202 SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
 203                 struct __kernel_old_timeval __user *, utimes)
 204 {
 205         return do_futimesat(dfd, filename, utimes);
 206 }
 207
 208 SYSCALL_DEFINE2(utimes, char __user *, filename,
 209                 struct __kernel_old_timeval __user *, utimes)
 210 {
 211         return do_futimesat(AT_FDCWD, filename, utimes);
 212 }
 213
 214 SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
 215 {
 216         struct timespec64 tv[2];
 217
 218         if (times) {
 219                 if (get_user(tv[0].tv_sec, &times->actime) ||
 220                     get_user(tv[1].tv_sec, &times->modtime))
 221                         return -EFAULT;
 222                 tv[0].tv_nsec = 0;
 223                 tv[1].tv_nsec = 0;
 224         }
 225         return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
 226 }
 227 #endif
 228
 229 #ifdef CONFIG_COMPAT_32BIT_TIME
 230 /*
 231  * Not all architectures have sys_utime, so implement this in terms
 232  * of sys_utimes.
 233  */
 234 #ifdef __ARCH_WANT_SYS_UTIME32
 235 SYSCALL_DEFINE2(utime32, const char __user *, filename,
 236                 struct old_utimbuf32 __user *, t)
 237 {
 238         struct timespec64 tv[2];
 239
 240         if (t) {
 241                 if (get_user(tv[0].tv_sec, &t->actime) ||
 242                     get_user(tv[1].tv_sec, &t->modtime))
 243                         return -EFAULT;
 244                 tv[0].tv_nsec = 0;
 245                 tv[1].tv_nsec = 0;
 246         }
 247         return do_utimes(AT_FDCWD, filename, t ? tv : NULL, 0);
 248 }
 249 #endif
 250
 251 SYSCALL_DEFINE4(utimensat_time32, unsigned int, dfd, const char __user *, filename, struct old_timespec32 __user *, t, int, flags)
 252 {
 253         struct timespec64 tv[2];
 254
 255         if  (t) {
 256                 if (get_old_timespec32(&tv[0], &t[0]) ||
 257                     get_old_timespec32(&tv[1], &t[1]))
 258                         return -EFAULT;
 259
 260                 if (tv[0].tv_nsec == UTIME_OMIT && tv[1].tv_nsec == UTIME_OMIT)
 261                         return 0;
 262         }
 263         return do_utimes(dfd, filename, t ? tv : NULL, flags);
 264 }
 265
 266 #ifdef __ARCH_WANT_SYS_UTIME32
 267 static long do_compat_futimesat(unsigned int dfd, const char __user *filename,
 268                                 struct old_timeval32 __user *t)
 269 {
 270         struct timespec64 tv[2];
 271
 272         if (t) {
 273                 if (get_user(tv[0].tv_sec, &t[0].tv_sec) ||
 274                     get_user(tv[0].tv_nsec, &t[0].tv_usec) ||
 275                     get_user(tv[1].tv_sec, &t[1].tv_sec) ||
 276                     get_user(tv[1].tv_nsec, &t[1].tv_usec))
 277                         return -EFAULT;
 278                 if (tv[0].tv_nsec >= 1000000 || tv[0].tv_nsec < 0 ||
 279                     tv[1].tv_nsec >= 1000000 || tv[1].tv_nsec < 0)
 280                         return -EINVAL;
 281                 tv[0].tv_nsec *= 1000;
 282                 tv[1].tv_nsec *= 1000;
 283         }
 284         return do_utimes(dfd, filename, t ? tv : NULL, 0);
 285 }
 286
 287 SYSCALL_DEFINE3(futimesat_time32, unsigned int, dfd,
 288                        const char __user *, filename,
 289                        struct old_timeval32 __user *, t)
 290 {
 291         return do_compat_futimesat(dfd, filename, t);
 292 }
 293
 294 SYSCALL_DEFINE2(utimes_time32, const char __user *, filename, struct old_timeval32 __user *, t)
 295 {
 296         return do_compat_futimesat(AT_FDCWD, filename, t);
 297 }
 298 #endif
 299 #endif