Commit Graph

7 Commits

Author SHA1 Message Date
Jan Kara
073931017b posix_acl: Clear SGID bit when setting file permissions
When file permissions are modified via chmod(2) and the user is not in
the owning group or capable of CAP_FSETID, the setgid bit is cleared in
inode_change_ok().  Setting a POSIX ACL via setxattr(2) sets the file
permissions as well as the new ACL, but doesn't clear the setgid bit in
a similar way; this allows to bypass the check in chmod(2).  Fix that.

References: CVE-2016-7097
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2016-09-22 10:55:32 +02:00
Andreas Gruenbacher
b8a7a3a667 posix_acl: Inode acl caching fixes
When get_acl() is called for an inode whose ACL is not cached yet, the
get_acl inode operation is called to fetch the ACL from the filesystem.
The inode operation is responsible for updating the cached acl with
set_cached_acl().  This is done without locking at the VFS level, so
another task can call set_cached_acl() or forget_cached_acl() before the
get_acl inode operation gets to calling set_cached_acl(), and then
get_acl's call to set_cached_acl() results in caching an outdate ACL.

Prevent this from happening by setting the cached ACL pointer to a
task-specific sentinel value before calling the get_acl inode operation.
Move the responsibility for updating the cached ACL from the get_acl
inode operations to get_acl().  There, only set the cached ACL if the
sentinel value hasn't changed.

The sentinel values are chosen to have odd values.  Likewise, the value
of ACL_NOT_CACHED is odd.  In contrast, ACL object pointers always have
an even value (ACLs are aligned in memory).  This allows to distinguish
uncached ACLs values from ACL objects.

In addition, switch from guarding inode->i_acl and inode->i_default_acl
upates by the inode->i_lock spinlock to using xchg() and cmpxchg().

Filesystems that do not want ACLs returned from their get_acl inode
operations to be cached must call forget_cached_acl() to prevent the VFS
from doing so.

(Patch written by Al Viro and Andreas Gruenbacher.)

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-31 00:30:15 -04:00
Andreas Gruenbacher
97d7929922 posix acls: Remove duplicate xattr name definitions
Remove POSIX_ACL_XATTR_{ACCESS,DEFAULT} and GFS2_POSIX_ACL_{ACCESS,DEFAULT}
and replace them with the definitions in <include/uapi/linux/xattr.h>.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06 21:25:17 -05:00
Christoph Hellwig
b0a7ab5706 hfsplus: use generic posix ACL infrastructure
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-01-25 23:58:20 -05:00
Christoph Hellwig
37bc15392a fs: make posix_acl_create more useful
Rename the current posix_acl_created to __posix_acl_create and add
a fully featured helper to set up the ACLs on file creation that
uses get_acl().

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-01-25 23:58:18 -05:00
Christoph Hellwig
5bf3258fd2 fs: make posix_acl_chmod more useful
Rename the current posix_acl_chmod to __posix_acl_chmod and add
a fully featured ACL chmod helper that uses the ->set_acl inode
operation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-01-25 23:58:18 -05:00
Vyacheslav Dubeyko
eef80d4ad1 hfsplus: implement POSIX ACLs support
Implement POSIX ACLs support in hfsplus driver.

Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11 15:59:01 -07:00