Messages in this thread | | | From | Andrew Lutomirski <> | Date | Tue, 20 Apr 2010 10:23:06 -0400 | Subject | Re: [PATCH 0/3] Taming execve, setuid, and LSMs |
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On Tue, Apr 20, 2010 at 8:37 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote: > On Mon, 2010-04-19 at 16:39 -0500, Serge E. Hallyn wrote: >> Quoting Andrew Lutomirski (luto@mit.edu):
>> > and LSM transitions. I >> > think this is a terrible idea for two reasons: >> > 1. LSM transitions already scare me enough, and if anyone relies on >> > them working in concert with setuid, then the mere act of separating >> > them might break things, even if the "privileged" (by LSM) app in >> > question is well-written. >> >> hmm... >> >> A good point. > > At least in the case of SELinux, context transitions upon execve are > already disabled in the nosuid case, and Eric's patch updated the > SELinux test accordingly. >
True, but I think it's still asking for trouble -- other LSMs could (and almost certainly will, especially the out-of-tree ones) do something, and I think that any action at all that an LSM takes in the bprm_set_creds hook for a nosuid (or whatever it's called) process is wrong or at best misguided.
Can you think of anything that an LSM should do (or even should be able to do) when a nosuid process calls exec, other than denying the request outright? With my patch, LSMs can still reject the open_exec call.
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