Messages in this thread | | | Date | Tue, 26 Jul 2011 03:40:13 +0400 | From | Solar Designer <> | Subject | Re: [kernel-hardening] [PATCH] move RLIMIT_NPROC check from set_user() to do_execve_common() |
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Vasiliy,
On Mon, Jul 25, 2011 at 09:14:23PM +0400, Vasiliy Kulikov wrote: > @@ -1433,6 +1433,19 @@ static int do_execve_common(const char *filename, > struct files_struct *displaced; > bool clear_in_exec; > int retval; > + const struct cred *cred = current_cred(); > + > + /* > + * We move the actual failure in case of RLIMIT_NPROC excess from > + * set*uid() to execve() because too many poorly written programs > + * don't check setuid() return code. Here we additionally recheck > + * whether NPROC limit is still exceeded. > + */ > + if ((current->flags & PF_NPROC_EXCEEDED) && > + atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) { > + retval = -EAGAIN; > + goto out_ret; > + }
Do you possibly need:
current->flags &= ~PF_NPROC_EXCEEDED;
somewhere after this point?
I think it's weird to have past set_user() failure affect other than the very next execve().
Perhaps also reset the flag on fork() because we have an RLIMIT_NPROC check on fork() anyway.
Thanks,
Alexander
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