fs/utimes.c

   1 #include <linux/compiler.h>
   2 #include <linux/file.h>
   3 #include <linux/fs.h>
   4 #include <linux/linkage.h>
   5 #include <linux/namei.h>
   6 #include <linux/sched.h>
   7 #include <linux/stat.h>
   8 #include <linux/utime.h>
   9 #include <linux/syscalls.h>
  10 #include <asm/uaccess.h>
  11 #include <asm/unistd.h>
  12
  13 #ifdef __ARCH_WANT_SYS_UTIME
  14
  15 /*
  16  * sys_utime() can be implemented in user-level using sys_utimes().
  17  * Is this for backwards compatibility?  If so, why not move it
  18  * into the appropriate arch directory (for those architectures that
  19  * need it).
  20  */
  21
  22 /* If times==NULL, set access and modification to current time,
  23  * must be owner or have write permission.
  24  * Else, update from *times, must be owner or super user.
  25  */
  26 asmlinkage long sys_utime(char __user *filename, struct utimbuf __user *times)
  27 {
  28         struct timespec tv[2];
  29
  30         if (times) {
  31                 if (get_user(tv[0].tv_sec, &times->actime) ||
  32                     get_user(tv[1].tv_sec, &times->modtime))
  33                         return -EFAULT;
  34                 tv[0].tv_nsec = 0;
  35                 tv[1].tv_nsec = 0;
  36         }
  37         return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
  38 }
  39
  40 #endif
  41
  42 static bool nsec_special(long nsec)
  43 {
  44         return nsec == UTIME_OMIT || nsec == UTIME_NOW;
  45 }
  46
  47 static bool nsec_valid(long nsec)
  48 {
  49         if (nsec_special(nsec))
  50                 return true;
  51
  52         return nsec >= 0 && nsec <= 999999999;
  53 }
  54
  55 /* If times==NULL, set access and modification to current time,
  56  * must be owner or have write permission.
  57  * Else, update from *times, must be owner or super user.
  58  */
  59 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
  60 {
  61         int error;
  62         struct nameidata nd;
  63         struct dentry *dentry;
  64         struct inode *inode;
  65         struct iattr newattrs;
  66         struct file *f = NULL;
  67
  68         error = -EINVAL;
  69         if (times && (!nsec_valid(times[0].tv_nsec) ||
  70                       !nsec_valid(times[1].tv_nsec))) {
  71                 goto out;
  72         }
  73
  74         if (flags & ~AT_SYMLINK_NOFOLLOW)
  75                 goto out;
  76
  77         if (filename == NULL && dfd != AT_FDCWD) {
  78                 error = -EINVAL;
  79                 if (flags & AT_SYMLINK_NOFOLLOW)
  80                         goto out;
  81
  82                 error = -EBADF;
  83                 f = fget(dfd);
  84                 if (!f)
  85                         goto out;
  86                 dentry = f->f_path.dentry;
  87         } else {
  88                 error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
  89                 if (error)
  90                         goto out;
  91
  92                 dentry = nd.path.dentry;
  93         }
  94
  95         inode = dentry->d_inode;
  96
  97         error = -EROFS;
  98         if (IS_RDONLY(inode))
  99                 goto dput_and_out;
 100
 101         /* Don't worry, the checks are done in inode_change_ok() */
 102         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 103         if (times) {
 104                 error = -EPERM;
 105                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 106                         goto dput_and_out;
 107
 108                 if (times[0].tv_nsec == UTIME_OMIT)
 109                         newattrs.ia_valid &= ~ATTR_ATIME;
 110                 else if (times[0].tv_nsec != UTIME_NOW) {
 111                         newattrs.ia_atime.tv_sec = times[0].tv_sec;
 112                         newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
 113                         newattrs.ia_valid |= ATTR_ATIME_SET;
 114                 }
 115
 116                 if (times[1].tv_nsec == UTIME_OMIT)
 117                         newattrs.ia_valid &= ~ATTR_MTIME;
 118                 else if (times[1].tv_nsec != UTIME_NOW) {
 119                         newattrs.ia_mtime.tv_sec = times[1].tv_sec;
 120                         newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
 121                         newattrs.ia_valid |= ATTR_MTIME_SET;
 122                 }
 123         }
 124
 125         /*
 126          * If times is NULL or both times are either UTIME_OMIT or
 127          * UTIME_NOW, then need to check permissions, because
 128          * inode_change_ok() won't do it.
 129          */
 130         if (!times || (nsec_special(times[0].tv_nsec) &&
 131                        nsec_special(times[1].tv_nsec))) {
 132                 error = -EACCES;
 133                 if (IS_IMMUTABLE(inode))
 134                         goto dput_and_out;
 135
 136                 if (!is_owner_or_cap(inode)) {
 137                         if (f) {
 138                                 if (!(f->f_mode & FMODE_WRITE))
 139                                         goto dput_and_out;
 140                         } else {
 141                                 error = vfs_permission(&nd, MAY_WRITE);
 142                                 if (error)
 143                                         goto dput_and_out;
 144                         }
 145                 }
 146         }
 147         mutex_lock(&inode->i_mutex);
 148         error = notify_change(dentry, &newattrs);
 149         mutex_unlock(&inode->i_mutex);
 150 dput_and_out:
 151         if (f)
 152                 fput(f);
 153         else
 154                 path_put(&nd.path);
 155 out:
 156         return error;
 157 }
 158
 159 asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
 160 {
 161         struct timespec tstimes[2];
 162
 163         if (utimes) {
 164                 if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
 165                         return -EFAULT;
 166                 if ((tstimes[0].tv_nsec == UTIME_OMIT ||
 167                      tstimes[0].tv_nsec == UTIME_NOW) &&
 168                     tstimes[0].tv_sec != 0)
 169                         return -EINVAL;
 170                 if ((tstimes[1].tv_nsec == UTIME_OMIT ||
 171                      tstimes[1].tv_nsec == UTIME_NOW) &&
 172                     tstimes[1].tv_sec != 0)
 173                         return -EINVAL;
 174
 175                 /* Nothing to do, we must not even check the path.  */
 176                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
 177                     tstimes[1].tv_nsec == UTIME_OMIT)
 178                         return 0;
 179         }
 180
 181         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
 182 }
 183
 184 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
 185 {
 186         struct timeval times[2];
 187         struct timespec tstimes[2];
 188
 189         if (utimes) {
 190                 if (copy_from_user(&times, utimes, sizeof(times)))
 191                         return -EFAULT;
 192
 193                 /* This test is needed to catch all invalid values.  If we
 194                    would test only in do_utimes we would miss those invalid
 195                    values truncated by the multiplication with 1000.  Note
 196                    that we also catch UTIME_{NOW,OMIT} here which are only
 197                    valid for utimensat.  */
 198                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
 199                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
 200                         return -EINVAL;
 201
 202                 tstimes[0].tv_sec = times[0].tv_sec;
 203                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
 204                 tstimes[1].tv_sec = times[1].tv_sec;
 205                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
 206         }
 207
 208         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
 209 }
 210
 211 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
 212 {
 213         return sys_futimesat(AT_FDCWD, filename, utimes);
 214 }