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_valid(long nsec)
  44 {
  45         if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
  46                 return true;
  47
  48         return nsec >= 0 && nsec <= 999999999;
  49 }
  50
  51 /* If times==NULL, set access and modification to current time,
  52  * must be owner or have write permission.
  53  * Else, update from *times, must be owner or super user.
  54  */
  55 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
  56 {
  57         int error;
  58         struct nameidata nd;
  59         struct dentry *dentry;
  60         struct inode *inode;
  61         struct iattr newattrs;
  62         struct file *f = NULL;
  63         struct vfsmount *mnt;
  64
  65         error = -EINVAL;
  66         if (times && (!nsec_valid(times[0].tv_nsec) ||
  67                       !nsec_valid(times[1].tv_nsec))) {
  68                 goto out;
  69         }
  70
  71         if (flags & ~AT_SYMLINK_NOFOLLOW)
  72                 goto out;
  73
  74         if (filename == NULL && dfd != AT_FDCWD) {
  75                 error = -EINVAL;
  76                 if (flags & AT_SYMLINK_NOFOLLOW)
  77                         goto out;
  78
  79                 error = -EBADF;
  80                 f = fget(dfd);
  81                 if (!f)
  82                         goto out;
  83                 dentry = f->f_path.dentry;
  84                 mnt = f->f_path.mnt;
  85         } else {
  86                 error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
  87                 if (error)
  88                         goto out;
  89
  90                 dentry = nd.path.dentry;
  91                 mnt = nd.path.mnt;
  92         }
  93
  94         inode = dentry->d_inode;
  95
  96         error = mnt_want_write(mnt);
  97         if (error)
  98                 goto dput_and_out;
  99
 100         /* Don't worry, the checks are done in inode_change_ok() */
 101         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 102         if (times) {
 103                 error = -EPERM;
 104                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 105                         goto mnt_drop_write_and_out;
 106
 107                 if (times[0].tv_nsec == UTIME_OMIT)
 108                         newattrs.ia_valid &= ~ATTR_ATIME;
 109                 else if (times[0].tv_nsec != UTIME_NOW) {
 110                         newattrs.ia_atime.tv_sec = times[0].tv_sec;
 111                         newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
 112                         newattrs.ia_valid |= ATTR_ATIME_SET;
 113                 }
 114
 115                 if (times[1].tv_nsec == UTIME_OMIT)
 116                         newattrs.ia_valid &= ~ATTR_MTIME;
 117                 else if (times[1].tv_nsec != UTIME_NOW) {
 118                         newattrs.ia_mtime.tv_sec = times[1].tv_sec;
 119                         newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
 120                         newattrs.ia_valid |= ATTR_MTIME_SET;
 121                 }
 122         } else {
 123                 error = -EACCES;
 124                 if (IS_IMMUTABLE(inode))
 125                         goto mnt_drop_write_and_out;
 126
 127                 if (!is_owner_or_cap(inode)) {
 128                         if (f) {
 129                                 if (!(f->f_mode & FMODE_WRITE))
 130                                         goto mnt_drop_write_and_out;
 131                         } else {
 132                                 error = vfs_permission(&nd, MAY_WRITE);
 133                                 if (error)
 134                                         goto mnt_drop_write_and_out;
 135                         }
 136                 }
 137         }
 138         mutex_lock(&inode->i_mutex);
 139         error = notify_change(dentry, &newattrs);
 140         mutex_unlock(&inode->i_mutex);
 141 mnt_drop_write_and_out:
 142         mnt_drop_write(mnt);
 143 dput_and_out:
 144         if (f)
 145                 fput(f);
 146         else
 147                 path_put(&nd.path);
 148 out:
 149         return error;
 150 }
 151
 152 asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
 153 {
 154         struct timespec tstimes[2];
 155
 156         if (utimes) {
 157                 if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
 158                         return -EFAULT;
 159                 if ((tstimes[0].tv_nsec == UTIME_OMIT ||
 160                      tstimes[0].tv_nsec == UTIME_NOW) &&
 161                     tstimes[0].tv_sec != 0)
 162                         return -EINVAL;
 163                 if ((tstimes[1].tv_nsec == UTIME_OMIT ||
 164                      tstimes[1].tv_nsec == UTIME_NOW) &&
 165                     tstimes[1].tv_sec != 0)
 166                         return -EINVAL;
 167
 168                 /* Nothing to do, we must not even check the path.  */
 169                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
 170                     tstimes[1].tv_nsec == UTIME_OMIT)
 171                         return 0;
 172         }
 173
 174         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
 175 }
 176
 177 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
 178 {
 179         struct timeval times[2];
 180         struct timespec tstimes[2];
 181
 182         if (utimes) {
 183                 if (copy_from_user(&times, utimes, sizeof(times)))
 184                         return -EFAULT;
 185
 186                 /* This test is needed to catch all invalid values.  If we
 187                    would test only in do_utimes we would miss those invalid
 188                    values truncated by the multiplication with 1000.  Note
 189                    that we also catch UTIME_{NOW,OMIT} here which are only
 190                    valid for utimensat.  */
 191                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
 192                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
 193                         return -EINVAL;
 194
 195                 tstimes[0].tv_sec = times[0].tv_sec;
 196                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
 197                 tstimes[1].tv_sec = times[1].tv_sec;
 198                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
 199         }
 200
 201         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
 202 }
 203
 204 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
 205 {
 206         return sys_futimesat(AT_FDCWD, filename, utimes);
 207 }