lkml.org 
[lkml]   [2014]   [Feb]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [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

    --
    Richard Guy Briggs <rbriggs@redhat.com>
    Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
    Remote, Ottawa, Canada
    Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545


    \
     
     \ /
      Last update: 2014-02-19 21:21    [W:2.244 / U:0.308 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site