Red Hat Bugzilla – Bug 585286
IMA breaks users of the dentry_open kernel interface
Last modified: 2010-04-24 18:54:05 EDT
Description of problem:
The IMA subsystem adds an asymmetric interface to monitoring files. That is, in-kernel users of the dentry_open interface must register their open files with IMA, but the registrations are automatically deregistered by filp_close. IMA provides verbose debugging output if it sees a file being deregistered that wasn't registered earlier.
ima_path_check(), which must be used to perform the registration, is a GPL-only symbol, so enabling IMA in effect breaks the dentry_open interface for non-GPL kernel modules. Whilst such modules can continue to function, the volume of debugging produced by IMA (a dump_stack every time a file is closed) seriously hampers the performance of the machine.
Whilst this is a general problem, in particular it breaks the Linux version of OpenAFS, which uses the dentry_open interface to access its cache files.
I raised this problem on the linux-security-module list in December 2009, and as a result the IMA interface was redesigned to remove the asymmetry of the register/unregister process. Those changes are in 2.6.33 - see the thread beginning at http://osdir.com/ml/linux-security-module/2009-12/msg00015.html for more details.
Many institutional users of OpenAFS use it with RHEL, so it would be great to have this fixed before the final release.
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux major release. Product Management has requested further
review of this request by Red Hat Engineering, for potential inclusion in a Red
Hat Enterprise Linux Major release. This request is not yet committed for
I am going to mark this a duplicate of BZ 584901. Even though this BZ has a much better description of the real problem, that one was opened first. You should be able to find a patch which applies against RHEL6 in that BZ which should take care of this problem. I will be proposing that patch for inclusion in RHEL6 although it's final determination is not yet known.
*** This bug has been marked as a duplicate of bug 584901 ***
#584901 is private - would it be possible to make it accessible? I'd really like to keep track of this issue. Thanks.