Re: [PATCH] audit: add arch field to seccomp event log

On 14/02/18, Richard Guy Briggs wrote: > On 14/02/18, Steve Grubb wrote: > > On Tuesday, February 18, 2014 03:50:44 PM Richard Guy Briggs wrote: > > > > missing '=' but this isn't what audit_get_context() does... it's > > > > crappy naming... I'd think a combo of audit_dummy_context() and > > > > current->audit_context would be most appropriate. > > > > > > Ok. I think I finally understand audit_dummy_context(). Thanks for the > > > hint. However, it appears it is not useful in this sitation, since if > > > there is an audit_context, even a dummy context, it appears arch is > > > filled in. > > > > > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > > > @@ -2406,12 +2406,18 @@ void audit_core_dumps(long signr) > > > void __audit_seccomp(unsigned long syscall, long signr, int code) > > > { > > > struct audit_buffer *ab; > > > + struct audit_context *context = current->audit_context; > > > > > > ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_SECCOMP); > > > if (unlikely(!ab)) > > > return; > > > audit_log_task(ab); > > > audit_log_format(ab, " sig=%ld", signr); > > > + audit_log_format(ab, " arch="); > > > + if (context) > > > + audit_log_format(ab, "%x", context->arch); > > > + else > > > + audit_log_format(ab, "(null)"); > > > audit_log_format(ab, " syscall=%ld", syscall); > > > audit_log_format(ab, " compat=%d", is_compat_task()); > > > audit_log_format(ab, " ip=0x%lx", KSTK_EIP(current)); > > > > Is there anything that could be passed by the caller that might identify the > > syscall ABI when this call was blocked? '(null)' still makes syscall number > > uninterpretable. > > This is the way it is done in the existing record that prints a syscall > record in audit_log_exit(). > > It is set by the arch-dependent assembler linkage for > __audit_syscall_entry() or set by the arch-dependent ptrace code that > calls audit_syscall_entry(). In some arches there are a couple of > choices. > > > To pass this in to __audit_seccomp() as an arg, I'd have to add that arg > to: > __audit_seccomp() > audit_seccomp() > __secure_computing() > secure_computing() > > > As you've pointed out in IRC, there is a syscall_get_arch(current, regs) > that could be used to get the arch when an audit context is not yet created. s390x architecture doesn't have it defined. :(

> I was just looking for something like that... I am noticing that all > arches call a variant of syscall_trace_enter() which first calls > secure_computing() [which eventually calls __audit_seccomp()] *before* > calling audit_syscall_entry() [which eventually sets context->arch]. So > I'm not sure how task->audit_context->arch got set... Perhaps > __audit_syscall_entry() should just call syscall_get_arch() instead of > lugging it through the stack like it presently does. > > Is this going to give the same information? (I guess I should be able > to answer that question...) > > > -Steve > > - RGB - RGB