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 static bool nsec_valid(long nsec)
  42 {
  43         if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
  44                 return true;
  45
  46         return nsec >= 0 && nsec <= 999999999;
  47 }
  48
  49 /* If times==NULL, set access and modification to current time,
  50  * must be owner or have write permission.
  51  * Else, update from *times, must be owner or super user.
  52  */
  53 long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
  54 {
  55         int error;
  56         struct nameidata nd;
  57         struct dentry *dentry;
  58         struct inode *inode;
  59         struct iattr newattrs;
  60         struct file *f = NULL;
  61
  62         error = -EINVAL;
  63         if (times && (!nsec_valid(times[0].tv_nsec) ||
  64                       !nsec_valid(times[1].tv_nsec))) {
  65                 goto out;
  66         }
  67
  68         if (flags & ~AT_SYMLINK_NOFOLLOW)
  69                 goto out;
  70
  71         if (filename == NULL && dfd != AT_FDCWD) {
  72                 error = -EINVAL;
  73                 if (flags & AT_SYMLINK_NOFOLLOW)
  74                         goto out;
  75
  76                 error = -EBADF;
  77                 f = fget(dfd);
  78                 if (!f)
  79                         goto out;
  80                 dentry = f->f_path.dentry;
  81         } else {
  82                 error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
  83                 if (error)
  84                         goto out;
  85
  86                 dentry = nd.dentry;
  87         }
  88
  89         inode = dentry->d_inode;
  90
  91         error = -EROFS;
  92         if (IS_RDONLY(inode))
  93                 goto dput_and_out;
  94
  95         /* Don't worry, the checks are done in inode_change_ok() */
  96         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
  97         if (times) {
  98                 error = -EPERM;
  99                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 100                         goto dput_and_out;
 101
 102                 if (times[0].tv_nsec == UTIME_OMIT)
 103                         newattrs.ia_valid &= ~ATTR_ATIME;
 104                 else if (times[0].tv_nsec != UTIME_NOW) {
 105                         newattrs.ia_atime.tv_sec = times[0].tv_sec;
 106                         newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
 107                         newattrs.ia_valid |= ATTR_ATIME_SET;
 108                 }
 109
 110                 if (times[1].tv_nsec == UTIME_OMIT)
 111                         newattrs.ia_valid &= ~ATTR_MTIME;
 112                 else if (times[1].tv_nsec != UTIME_NOW) {
 113                         newattrs.ia_mtime.tv_sec = times[1].tv_sec;
 114                         newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
 115                         newattrs.ia_valid |= ATTR_MTIME_SET;
 116                 }
 117         } else {
 118                 error = -EACCES;
 119                 if (IS_IMMUTABLE(inode))
 120                         goto dput_and_out;
 121
 122                 if (!is_owner_or_cap(inode)) {
 123                         if (f) {
 124                                 if (!(f->f_mode & FMODE_WRITE))
 125                                         goto dput_and_out;
 126                         } else {
 127                                 error = vfs_permission(&nd, MAY_WRITE);
 128                                 if (error)
 129                                         goto dput_and_out;
 130                         }
 131                 }
 132         }
 133         mutex_lock(&inode->i_mutex);
 134         error = notify_change(dentry, &newattrs);
 135         mutex_unlock(&inode->i_mutex);
 136 dput_and_out:
 137         if (f)
 138                 fput(f);
 139         else
 140                 path_release(&nd);
 141 out:
 142         return error;
 143 }
 144
 145 asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
 146 {
 147         struct timespec tstimes[2];
 148
 149         if (utimes) {
 150                 if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
 151                         return -EFAULT;
 152                 if ((tstimes[0].tv_nsec == UTIME_OMIT ||
 153                      tstimes[0].tv_nsec == UTIME_NOW) &&
 154                     tstimes[0].tv_sec != 0)
 155                         return -EINVAL;
 156                 if ((tstimes[1].tv_nsec == UTIME_OMIT ||
 157                      tstimes[1].tv_nsec == UTIME_NOW) &&
 158                     tstimes[1].tv_sec != 0)
 159                         return -EINVAL;
 160
 161                 /* Nothing to do, we must not even check the path.  */
 162                 if (tstimes[0].tv_nsec == UTIME_OMIT &&
 163                     tstimes[1].tv_nsec == UTIME_OMIT)
 164                         return 0;
 165         }
 166
 167         return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
 168 }
 169
 170 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
 171 {
 172         struct timeval times[2];
 173         struct timespec tstimes[2];
 174
 175         if (utimes) {
 176                 if (copy_from_user(&times, utimes, sizeof(times)))
 177                         return -EFAULT;
 178
 179                 /* This test is needed to catch all invalid values.  If we
 180                    would test only in do_utimes we would miss those invalid
 181                    values truncated by the multiplication with 1000.  Note
 182                    that we also catch UTIME_{NOW,OMIT} here which are only
 183                    valid for utimensat.  */
 184                 if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
 185                     times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
 186                         return -EINVAL;
 187
 188                 tstimes[0].tv_sec = times[0].tv_sec;
 189                 tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
 190                 tstimes[1].tv_sec = times[1].tv_sec;
 191                 tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
 192         }
 193
 194         return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
 195 }
 196
 197 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
 198 {
 199         return sys_futimesat(AT_FDCWD, filename, utimes);
 200 }