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/mount.h>
   6 #include <linux/namei.h>
   7 #include <linux/sched.h>
   8 #include <linux/stat.h>
   9 #include <linux/utime.h>
  10 #include <linux/syscalls.h>
  11 #include <asm/uaccess.h>
  12 #include <asm/unistd.h>
  13
  14 #ifdef __ARCH_WANT_SYS_UTIME
  15
  16 /*
  17  * sys_utime() can be implemented in user-level using sys_utimes().
  18  * Is this for backwards compatibility?  If so, why not move it
  19  * into the appropriate arch directory (for those architectures that
  20  * need it).
  21  */
  22
  23 /* If times==NULL, set access and modification to current time,
  24  * must be owner or have write permission.
  25  * Else, update from *times, must be owner or super user.
  26  */
  27 asmlinkage long sys_utime(char __user *filename, struct utimbuf __user *times)
  28 {
  29         struct timespec tv[2];
  30
  31         if (times) {
  32                 if (get_user(tv[0].tv_sec, &times->actime) ||
  33                     get_user(tv[1].tv_sec, &times->modtime))
  34                         return -EFAULT;
  35                 tv[0].tv_nsec = 0;
  36                 tv[1].tv_nsec = 0;
  37         }
  38         return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
  39 }
  40
  41 #endif
  42
  43 static bool nsec_special(long nsec)
  44 {
  45         return nsec == UTIME_OMIT || nsec == UTIME_NOW;
  46 }
  47
  48 static bool nsec_valid(long nsec)
  49 {
  50         if (nsec_special(nsec))
  51                 return true;
  52
  53         return nsec >= 0 && nsec <= 999999999;
  54 }
  55
  56 /* If times==NULL, set access and modification to current time,
  57  * must be owner or have write permission.
  58  * Else, update from *times, must be owner or super user.
  59  */
  60 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
  61 {
  62         int error;
  63         struct nameidata nd;
  64         struct dentry *dentry;
  65         struct inode *inode;
  66         struct iattr newattrs;
  67         struct file *f = NULL;
  68         struct vfsmount *mnt;
  69
  70         error = -EINVAL;
  71         if (times && (!nsec_valid(times[0].tv_nsec) ||
  72                       !nsec_valid(times[1].tv_nsec))) {
  73                 goto out;
  74         }
  75
  76         if (flags & ~AT_SYMLINK_NOFOLLOW)
  77                 goto out;
  78
  79         if (filename == NULL && dfd != AT_FDCWD) {
  80                 error = -EINVAL;
  81                 if (flags & AT_SYMLINK_NOFOLLOW)
  82                         goto out;
  83
  84                 error = -EBADF;
  85                 f = fget(dfd);
  86                 if (!f)
  87                         goto out;
  88                 dentry = f->f_path.dentry;
  89                 mnt = f->f_path.mnt;
  90         } else {
  91                 error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
  92                 if (error)
  93                         goto out;
  94
  95                 dentry = nd.path.dentry;
  96                 mnt = nd.path.mnt;
  97         }
  98
  99         inode = dentry->d_inode;
 100
 101         error = mnt_want_write(mnt);
 102         if (error)
 103                 goto dput_and_out;
 104
 105         /* Don't worry, the checks are done in inode_change_ok() */
 106         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 107         if (times) {
 108                 error = -EPERM;
 109                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 110                         goto mnt_drop_write_and_out;
 111
 112                 if (times[0].tv_nsec == UTIME_OMIT)
 113                         newattrs.ia_valid &= ~ATTR_ATIME;
 114                 else if (times[0].tv_nsec != UTIME_NOW) {
 115                         newattrs.ia_atime.tv_sec = times[0].tv_sec;
 116                         newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
 117                         newattrs.ia_valid |= ATTR_ATIME_SET;
 118                 }
 119
 120                 if (times[1].tv_nsec == UTIME_OMIT)
 121                         newattrs.ia_valid &= ~ATTR_MTIME;
 122                 else if (times[1].tv_nsec != UTIME_NOW) {
 123                         newattrs.ia_mtime.tv_sec = times[1].tv_sec;
 124                         newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
 125                         newattrs.ia_valid |= ATTR_MTIME_SET;
 126                 }
 127         }
 128
 129         /*
 130          * If times is NULL or both times are either UTIME_OMIT or
 131          * UTIME_NOW, then need to check permissions, because
 132          * inode_change_ok() won't do it.
 133          */
 134         if (!times || (nsec_special(times[0].tv_nsec) &&
 135                        nsec_special(times[1].tv_nsec))) {
 136                 error = -EACCES;
 137                 if (IS_IMMUTABLE(inode))
 138                         goto mnt_drop_write_and_out;
 139
 140                 if (!is_owner_or_cap(inode)) {
 141                         if (f) {
 142                                 if (!(f->f_mode & FMODE_WRITE))
 143                                         goto mnt_drop_write_and_out;
 144                         } else {
 145                                 error = vfs_permission(&nd, MAY_WRITE);
 146                                 if (error)
 147                                         goto mnt_drop_write_and_out;
 148                         }
 149                 }
 150         }
 151         mutex_lock(&inode->i_mutex);
 152         error = notify_change(dentry, &newattrs);
 153         mutex_unlock(&inode->i_mutex);
 154 mnt_drop_write_and_out:
 155         mnt_drop_write(mnt);
 156 dput_and_out:
 157         if (f)
 158                 fput(f);
 159         else
 160                 path_put(&nd.path);
 161 out:
 162         return error;
 163 }
 164
 165 asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
 166 {
 167         struct timespec tstimes[2];
 168
 169         if (utimes) {
 170                 if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
 171                         return -EFAULT;
 172                 if ((tstimes[0].tv_nsec == UTIME_OMIT ||
 173                      tstimes[0].tv_nsec == UTIME_NOW) &&
 174                     tstimes[0].tv_sec != 0)
 175                         return -EINVAL;
 176                 if ((tstimes[1].tv_nsec == UTIME_OMIT ||
 177                      tstimes[1].tv_nsec == UTIME_NOW) &&
 178                     tstimes[1].tv_sec != 0)
 179                         return -EINVAL;
 180
 181                 /* Nothing to do, we must not even check the path.  */
 182                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
 183                     tstimes[1].tv_nsec == UTIME_OMIT)
 184                         return 0;
 185         }
 186
 187         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
 188 }
 189
 190 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
 191 {
 192         struct timeval times[2];
 193         struct timespec tstimes[2];
 194
 195         if (utimes) {
 196                 if (copy_from_user(&times, utimes, sizeof(times)))
 197                         return -EFAULT;
 198
 199                 /* This test is needed to catch all invalid values.  If we
 200                    would test only in do_utimes we would miss those invalid
 201                    values truncated by the multiplication with 1000.  Note
 202                    that we also catch UTIME_{NOW,OMIT} here which are only
 203                    valid for utimensat.  */
 204                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
 205                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
 206                         return -EINVAL;
 207
 208                 tstimes[0].tv_sec = times[0].tv_sec;
 209                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
 210                 tstimes[1].tv_sec = times[1].tv_sec;
 211                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
 212         }
 213
 214         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
 215 }
 216
 217 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
 218 {
 219         return sys_futimesat(AT_FDCWD, filename, utimes);
 220 }