BugLink: http://bugs.launchpad.net/bugs/955892
All failures from __d_path where being treated as disconnected paths,
however __d_path can also fail when the generated pathname is too long.
The initial ENAMETOOLONG error was being lost, and ENAMETOOLONG was only
returned if the subsequent dentry_path call resulted in that error. Other
wise if the path was split across a mount point such that the dentry_path
fit within the buffer when the __d_path did not the failure was treated
as a disconnected path.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Move the path name lookup failure messages into the main path name lookup
routine, as the information is useful in more than just aa_path_perm.
Also rename aa_get_name to aa_path_name as it is not getting a reference
counted object with a corresponding put fn.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>
When __d_path and d_absolute_path fail due to the name being outside of
the current namespace no name is reported. Use dentry_path to provide
some hint as to which file was being accessed.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>
The returning of -ESATLE when a path lookup fails as disconnected is wrong.
Since AppArmor is rejecting the access return -EACCES instead.
This also fixes a bug in complain (learning) mode where disconnected paths
are denied because -ESTALE errors are not ignored causing failures that
can change application behavior.
Signed-off-by: John Johansen <john.johansen@canonical.com>
When a chroot relative pathname lookup fails it is falling through to
do a d_absolute_path lookup. This is incorrect as d_absolute_path should
only be used to lookup names for namespace absolute paths.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>
it's not needed anymore; we used to, back when we had to do
mount_subtree() by hand, complete with put_mnt_ns() in it.
No more... Apparmor didn't need it since the __d_path() fix.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
__d_path() API is asking for trouble and in case of apparmor d_namespace_path()
getting just that. The root cause is that when __d_path() misses the root
it had been told to look for, it stores the location of the most remote ancestor
in *root. Without grabbing references. Sure, at the moment of call it had
been pinned down by what we have in *path. And if we raced with umount -l, we
could have very well stopped at vfsmount/dentry that got freed as soon as
prepend_path() dropped vfsmount_lock.
It is safe to compare these pointers with pre-existing (and known to be still
alive) vfsmount and dentry, as long as all we are asking is "is it the same
address?". Dereferencing is not safe and apparmor ended up stepping into
that. d_namespace_path() really wants to examine the place where we stopped,
even if it's not connected to our namespace. As the result, it looked
at ->d_sb->s_magic of a dentry that might've been already freed by that point.
All other callers had been careful enough to avoid that, but it's really
a bad interface - it invites that kind of trouble.
The fix is fairly straightforward, even though it's bigger than I'd like:
* prepend_path() root argument becomes const.
* __d_path() is never called with NULL/NULL root. It was a kludge
to start with. Instead, we have an explicit function - d_absolute_root().
Same as __d_path(), except that it doesn't get root passed and stops where
it stops. apparmor and tomoyo are using it.
* __d_path() returns NULL on path outside of root. The main
caller is show_mountinfo() and that's precisely what we pass root for - to
skip those outside chroot jail. Those who don't want that can (and do)
use d_path().
* __d_path() root argument becomes const. Everyone agrees, I hope.
* apparmor does *NOT* try to use __d_path() or any of its variants
when it sees that path->mnt is an internal vfsmount. In that case it's
definitely not mounted anywhere and dentry_path() is exactly what we want
there. Handling of sysctl()-triggered weirdness is moved to that place.
* if apparmor is asked to do pathname relative to chroot jail
and __d_path() tells it we it's not in that jail, the sucker just calls
d_absolute_path() instead. That's the other remaining caller of __d_path(),
BTW.
* seq_path_root() does _NOT_ return -ENAMETOOLONG (it's stupid anyway -
the normal seq_file logics will take care of growing the buffer and redoing
the call of ->show() just fine). However, if it gets path not reachable
from root, it returns SEQ_SKIP. The only caller adjusted (i.e. stopped
ignoring the return value as it used to do).
Reviewed-by: John Johansen <john.johansen@canonical.com>
ACKed-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
All callers take dcache_lock just around the call to __d_path, so
take the lock into it in preparation of getting rid of dcache_lock.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The 2.6.36 kernel has refactored __d_path() so that it no longer appends
" (deleted)" to unlinked paths. So drop the hack that was used to detect
and remove the appended string.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
Miscellaneous functions and defines needed by AppArmor, including
the base path resolution routines.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
John Johansen
Al Viro
Christoph Hellwig
Nick Piggin