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