Not sure how many you are speaking for when you say "We are very dumb". :)
Thanks for catching this. I'l remove this arch thing in v2. To address your other concern about registers, I'll add some comments to the code, something like: "%rdi,%r8,%r9 are not used by seccomp filters; it's safe to not save them." - xi On Fri, Apr 26, 2013 at 12:14 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: > On Fri, 2013-04-26 at 12:02 -0400, Xi Wang wrote: >> On Fri, Apr 26, 2013 at 11:11 AM, Eric Dumazet <eric.duma...@gmail.com> >> wrote: >> > 1) 'current' at the time the code is jitted (compiled) is not the >> > 'current' at the time the filter will be evaluated. >> > >> > On x86_64, if CONFIG_IA32_EMULATION=y, syscall_get_arch() evaluates to : >> > >> > if (task_thread_info(task)->status & TS_COMPAT) >> > return AUDIT_ARCH_I386; >> > return AUDIT_ARCH_X86_64; >> > >> > So your code is completely wrong. >> >> Just to be clear, are you worrying about a process changing its >> personality after installing seccomp filters? > > You didn't explained how things worked. > > Are you assuming we network guys know everything ? > > Just to make it very clear : > > We are very dumb and you must explain us everything. > > If process would not change personality, why do we have get_arch() at > all ? Why isn't it optimized outside of the JIT itself, in the generic > seccomp checker, its a single "A = K" instruction after all. > > Why this part is even in the x86 BPF JIT ? > > To me it looks like _if_ get_arch() is provided in BPF, its for a > reason, and your implementation looks very suspicious, if not buggy. > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
