Messages in this thread | | | From | Kees Cook <> | Date | Tue, 30 Oct 2018 14:32:33 -0700 | Subject | Re: [PATCH v8 1/2] seccomp: add a return code to trap to userspace |
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On Tue, Oct 30, 2018 at 10:21 AM, Tycho Andersen <tycho@tycho.ws> wrote: > On Tue, Oct 30, 2018 at 05:39:26PM +0100, Oleg Nesterov wrote: >> On 10/30, Oleg Nesterov wrote: >> > >> > On 10/30, Tycho Andersen wrote: >> > > >> > > @@ -828,6 +823,11 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, >> > > */ >> > > rmb(); >> > > >> > > + if (!sd) { >> > > + populate_seccomp_data(&sd_local); >> > > + sd = &sd_local; >> > > + } >> > > + >> > >> > To me it would be more clean to remove the "if (!sd)" check, case(SECCOMP_RET_TRACE) >> > in __seccomp_filter() can simply do populate_seccomp_data(&sd_local) unconditionally >> > and pass &sd_local to __seccomp_filter(). >> >> Ah, please ignore, emulate_vsyscall() does secure_computing(NULL).
Right.
>> >> Btw. why __seccomp_filter() doesn't return a boolean?
Because it was wrapped by __secure_computing(). *shrug* The common method in the kernel is to use int and 0=ok.
>> Or at least, why can't case(SECCOMP_RET_TRACE) simply do >> >> return __seccomp_filter(this_syscall, NULL, true); >> >> ? > > Yeah, at least the second one definitely makes sense. I can add that > as a patch in the next version of this series unless Kees does it > before.
I'd like to avoid changing the return value of __secure_computing() to just avoid having to touch all the callers. And I'd prefer not to change __seccomp_filter() to a bool, since I'd like the return values to be consistent through the call chain.
I find the existing code more readable than a single-line return, just because it's very explicit. I don't want to have to think any harder when reading seccomp. ;)
-Kees
-- Kees Cook
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