utimensat implementation

Implement utimensat(2) which is an extension to futimesat(2) in that it

a) supports nano-second resolution for the timestamps
b) allows to selectively ignore the atime/mtime value
c) allows to selectively use the current time for either atime or mtime
d) supports changing the atime/mtime of a symlink itself along the lines
   of the BSD lutimes(3) functions

For this change the internally used do_utimes() functions was changed to
accept a timespec time value and an additional flags parameter.

Additionally the sys_utime function was changed to match compat_sys_utime
which already use do_utimes instead of duplicating the work.

Also, the completely missing futimensat() functionality is added.  We have
such a function in glibc but we have to resort to using /proc/self/fd/* which
not everybody likes (chroot etc).

Test application (the syscall number will need per-arch editing):

#include <errno.h>
#include <fcntl.h>
#include <time.h>
#include <sys/time.h>
#include <stddef.h>
#include <syscall.h>

#define __NR_utimensat 280

#define UTIME_NOW       ((1l << 30) - 1l)
#define UTIME_OMIT      ((1l << 30) - 2l)

int
main(void)
{
  int status = 0;

  int fd = open("ttt", O_RDWR|O_CREAT|O_EXCL, 0666);
  if (fd == -1)
    error (1, errno, "failed to create test file \"ttt\"");

  struct stat64 st1;
  if (fstat64 (fd, &st1) != 0)
    error (1, errno, "fstat failed");

  struct timespec t[2];
  t[0].tv_sec = 0;
  t[0].tv_nsec = 0;
  t[1].tv_sec = 0;
  t[1].tv_nsec = 0;
  if (syscall(__NR_utimensat, AT_FDCWD, "ttt", t, 0) != 0)
    error (1, errno, "utimensat failed");

  struct stat64 st2;
  if (fstat64 (fd, &st2) != 0)
    error (1, errno, "fstat failed");

  if (st2.st_atim.tv_sec != 0 || st2.st_atim.tv_nsec != 0)
    {
      puts ("atim not reset to zero");
      status = 1;
    }
  if (st2.st_mtim.tv_sec != 0 || st2.st_mtim.tv_nsec != 0)
    {
      puts ("mtim not reset to zero");
      status = 1;
    }
  if (status != 0)
    goto out;

  t[0] = st1.st_atim;
  t[1].tv_sec = 0;
  t[1].tv_nsec = UTIME_OMIT;
  if (syscall(__NR_utimensat, AT_FDCWD, "ttt", t, 0) != 0)
    error (1, errno, "utimensat failed");

  if (fstat64 (fd, &st2) != 0)
    error (1, errno, "fstat failed");

  if (st2.st_atim.tv_sec != st1.st_atim.tv_sec
      || st2.st_atim.tv_nsec != st1.st_atim.tv_nsec)
    {
      puts ("atim not set");
      status = 1;
    }
  if (st2.st_mtim.tv_sec != 0 || st2.st_mtim.tv_nsec != 0)
    {
      puts ("mtim changed from zero");
      status = 1;
    }
  if (status != 0)
    goto out;

  t[0].tv_sec = 0;
  t[0].tv_nsec = UTIME_OMIT;
  t[1] = st1.st_mtim;
  if (syscall(__NR_utimensat, AT_FDCWD, "ttt", t, 0) != 0)
    error (1, errno, "utimensat failed");

  if (fstat64 (fd, &st2) != 0)
    error (1, errno, "fstat failed");

  if (st2.st_atim.tv_sec != st1.st_atim.tv_sec
      || st2.st_atim.tv_nsec != st1.st_atim.tv_nsec)
    {
      puts ("mtim changed from original time");
      status = 1;
    }
  if (st2.st_mtim.tv_sec != st1.st_mtim.tv_sec
      || st2.st_mtim.tv_nsec != st1.st_mtim.tv_nsec)
    {
      puts ("mtim not set");
      status = 1;
    }
  if (status != 0)
    goto out;

  sleep (2);

  t[0].tv_sec = 0;
  t[0].tv_nsec = UTIME_NOW;
  t[1].tv_sec = 0;
  t[1].tv_nsec = UTIME_NOW;
  if (syscall(__NR_utimensat, AT_FDCWD, "ttt", t, 0) != 0)
    error (1, errno, "utimensat failed");

  if (fstat64 (fd, &st2) != 0)
    error (1, errno, "fstat failed");

  struct timeval tv;
  gettimeofday(&tv,NULL);

  if (st2.st_atim.tv_sec <= st1.st_atim.tv_sec
      || st2.st_atim.tv_sec > tv.tv_sec)
    {
      puts ("atim not set to NOW");
      status = 1;
    }
  if (st2.st_mtim.tv_sec <= st1.st_mtim.tv_sec
      || st2.st_mtim.tv_sec > tv.tv_sec)
    {
      puts ("mtim not set to NOW");
      status = 1;
    }

  if (symlink ("ttt", "tttsym") != 0)
    error (1, errno, "cannot create symlink");

  t[0].tv_sec = 0;
  t[0].tv_nsec = 0;
  t[1].tv_sec = 0;
  t[1].tv_nsec = 0;
  if (syscall(__NR_utimensat, AT_FDCWD, "tttsym", t, AT_SYMLINK_NOFOLLOW) != 0)
    error (1, errno, "utimensat failed");

  if (lstat64 ("tttsym", &st2) != 0)
    error (1, errno, "lstat failed");

  if (st2.st_atim.tv_sec != 0 || st2.st_atim.tv_nsec != 0)
    {
      puts ("symlink atim not reset to zero");
      status = 1;
    }
  if (st2.st_mtim.tv_sec != 0 || st2.st_mtim.tv_nsec != 0)
    {
      puts ("symlink mtim not reset to zero");
      status = 1;
    }
  if (status != 0)
    goto out;

  t[0].tv_sec = 1;
  t[0].tv_nsec = 0;
  t[1].tv_sec = 1;
  t[1].tv_nsec = 0;
  if (syscall(__NR_utimensat, fd, NULL, t, 0) != 0)
    error (1, errno, "utimensat failed");

  if (fstat64 (fd, &st2) != 0)
    error (1, errno, "fstat failed");

  if (st2.st_atim.tv_sec != 1 || st2.st_atim.tv_nsec != 0)
    {
      puts ("atim not reset to one");
      status = 1;
    }
  if (st2.st_mtim.tv_sec != 1 || st2.st_mtim.tv_nsec != 0)
    {
      puts ("mtim not reset to one");
      status = 1;
    }

  if (status == 0)
     puts ("all OK");

 out:
  close (fd);
  unlink ("ttt");
  unlink ("tttsym");

  return status;
}

[akpm@linux-foundation.org: add missing i386 syscall table entry]
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Cc: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 102 insertions, 60 deletions

diff --git a/fs/utimes.c b/fs/utimes.c
index 99cf2cb11fec..480f7c8c29da 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -1,8 +1,10 @@
 #include <linux/compiler.h>
+#include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/linkage.h>
 #include <linux/namei.h>
 #include <linux/sched.h>
+#include <linux/stat.h>
 #include <linux/utime.h>
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -20,54 +22,18 @@
  * must be owner or have write permission.
  * Else, update from *times, must be owner or super user.
  */
-asmlinkage long sys_utime(char __user * filename, struct utimbuf __user * times)
+asmlinkage long sys_utime(char __user *filename, struct utimbuf __user *times)
 {
-        int error;
-        struct nameidata nd;
-        struct inode * inode;
-        struct iattr newattrs;
+        struct timespec tv[2];
 
-        error = user_path_walk(filename, &nd);
-        if (error)
-                goto out;
-        inode = nd.dentry->d_inode;
-
-        error = -EROFS;
-        if (IS_RDONLY(inode))
-                goto dput_and_out;
-
-        /* Don't worry, the checks are done in inode_change_ok() */
-        newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
         if (times) {
-                error = -EPERM;
-                if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
-                        goto dput_and_out;
-
-                error = get_user(newattrs.ia_atime.tv_sec, &times->actime);
-                newattrs.ia_atime.tv_nsec = 0;
-                if (!error)
-                        error = get_user(newattrs.ia_mtime.tv_sec, &times->modtime);
-                newattrs.ia_mtime.tv_nsec = 0;
-                if (error)
-                        goto dput_and_out;
-
-                newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
-        } else {
-                error = -EACCES;
-                if (IS_IMMUTABLE(inode))
-                        goto dput_and_out;
-
-                if (current->fsuid != inode->i_uid &&
-                    (error = vfs_permission(&nd, MAY_WRITE)) != 0)
-                        goto dput_and_out;
+                if (get_user(tv[0].tv_sec, &times->actime) ||
+                    get_user(tv[1].tv_sec, &times->modtime))
+                        return -EFAULT;
+                tv[0].tv_nsec = 0;
+                tv[1].tv_nsec = 0;
         }
-        mutex_lock(&inode->i_mutex);
-        error = notify_change(nd.dentry, &newattrs);
-        mutex_unlock(&inode->i_mutex);
-dput_and_out:
-        path_release(&nd);
-out:
-        return error;
+        return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
 }
 
 #endif
@@ -76,18 +42,38 @@ out:
  * must be owner or have write permission.
  * Else, update from *times, must be owner or super user.
  */
-long do_utimes(int dfd, char __user *filename, struct timeval *times)
+long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
 {
         int error;
         struct nameidata nd;
-        struct inode * inode;
+        struct dentry *dentry;
+        struct inode *inode;
         struct iattr newattrs;
+        struct file *f = NULL;
 
-        error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);
-
-        if (error)
+        error = -EINVAL;
+        if (flags & ~AT_SYMLINK_NOFOLLOW)
                 goto out;
-        inode = nd.dentry->d_inode;
+
+        if (filename == NULL && dfd != AT_FDCWD) {
+                error = -EINVAL;
+                if (flags & AT_SYMLINK_NOFOLLOW)
+                        goto out;
+
+                error = -EBADF;
+                f = fget(dfd);
+                if (!f)
+                        goto out;
+                dentry = f->f_path.dentry;
+        } else {
+                error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
+                if (error)
+                        goto out;
+
+                dentry = nd.dentry;
+        }
+
+        inode = dentry->d_inode;
 
         error = -EROFS;
         if (IS_RDONLY(inode))
@@ -100,11 +86,21 @@ long do_utimes(int dfd, char __user *filename, struct timeval *times)
                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
                         goto dput_and_out;
 
-                newattrs.ia_atime.tv_sec = times[0].tv_sec;
-                newattrs.ia_atime.tv_nsec = times[0].tv_usec * 1000;
-                newattrs.ia_mtime.tv_sec = times[1].tv_sec;
-                newattrs.ia_mtime.tv_nsec = times[1].tv_usec * 1000;
-                newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
+                if (times[0].tv_nsec == UTIME_OMIT)
+                        newattrs.ia_valid &= ~ATTR_ATIME;
+                else if (times[0].tv_nsec != UTIME_NOW) {
+                        newattrs.ia_atime.tv_sec = times[0].tv_sec;
+                        newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
+                        newattrs.ia_valid |= ATTR_ATIME_SET;
+                }
+
+                if (times[1].tv_nsec == UTIME_OMIT)
+                        newattrs.ia_valid &= ~ATTR_MTIME;
+                else if (times[1].tv_nsec != UTIME_NOW) {
+                        newattrs.ia_mtime.tv_sec = times[1].tv_sec;
+                        newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
+                        newattrs.ia_valid |= ATTR_MTIME_SET;
+                }
         } else {
                 error = -EACCES;
                 if (IS_IMMUTABLE(inode))
@@ -115,21 +111,67 @@ long do_utimes(int dfd, char __user *filename, struct timeval *times)
                         goto dput_and_out;
         }
         mutex_lock(&inode->i_mutex);
-        error = notify_change(nd.dentry, &newattrs);
+        error = notify_change(dentry, &newattrs);
         mutex_unlock(&inode->i_mutex);
 dput_and_out:
-        path_release(&nd);
+        if (f)
+                fput(f);
+        else
+                path_release(&nd);
 out:
         return error;
 }
 
+asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
+{
+        struct timespec tstimes[2];
+
+        if (utimes) {
+                if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
+                        return -EFAULT;
+                if ((tstimes[0].tv_nsec == UTIME_OMIT ||
+                     tstimes[0].tv_nsec == UTIME_NOW) &&
+                    tstimes[0].tv_sec != 0)
+                        return -EINVAL;
+                if ((tstimes[1].tv_nsec == UTIME_OMIT ||
+                     tstimes[1].tv_nsec == UTIME_NOW) &&
+                    tstimes[1].tv_sec != 0)
+                        return -EINVAL;
+
+                /* Nothing to do, we must not even check the path.  */
+                if (tstimes[0].tv_nsec == UTIME_OMIT &&
+                    tstimes[1].tv_nsec == UTIME_OMIT)
+                        return 0;
+        }
+
+        return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
+}
+
 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
 {
         struct timeval times[2];
+        struct timespec tstimes[2];
+
+        if (utimes) {
+                if (copy_from_user(&times, utimes, sizeof(times)))
+                        return -EFAULT;
+
+                /* This test is needed to catch all invalid values.  If we
+                   would test only in do_utimes we would miss those invalid
+                   values truncated by the multiplication with 1000.  Note
+                   that we also catch UTIME_{NOW,OMIT} here which are only
+                   valid for utimensat.  */
+                if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
+                    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
+                        return -EINVAL;
+
+                tstimes[0].tv_sec = times[0].tv_sec;
+                tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
+                tstimes[1].tv_sec = times[1].tv_sec;
+                tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
+        }
 
-        if (utimes && copy_from_user(&times, utimes, sizeof(times)))
-                return -EFAULT;
-        return do_utimes(dfd, filename, utimes ? times : NULL);
+        return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
 }
 
 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)