On Thu, Feb 23, 2012 at 4:33 PM, Markus Gutschke [off-list ref] wrote:

On Thu, Feb 23, 2012 at 14:15, Indan Zupancic [off-list ref] wrote:

quoted

What about making SECCOMP_RET_TRAP dump core/send SIGSYS if there is
no tracer with PTRACE_O_SECCOMP set?

Please don't make things dependent on having a tracer. There are
applications that don't really need a tracer; in fact, these are
typically the exact same applications that can benefit from receiving
SIGSYS and then handling it internally.

If a tracer was required to set this up, it would make it difficult to
use gdb, strace, or any other common debugging tools.

quoted

Sending SIGSYS is useful, but it's quite a bit less useful if user
space can't handle it in a signal handler, so I don't think it's
worth it to make a unblockable version.

Maybe, I am not parsing your e-mail correctly. But don't we already
get the desired behavior, if SIGSYS is treated the same as any other
synchronous signal? If it is unblocked and has a handler, the
application can decide to handle it. If neither one of these
conditions is true, it terminates the program. Ulimits and
PR_SET_DUMPABLE determine whether a core file is generated.

Yeah - the current patchset does that just fine. The tweak I was
proposing was making ti possible to deliver an SIGSYS that always uses
SIG_DFL so that you don't have to play with signal call enforcement in
the filters.

This is a pretty minor tweak either way.
cheers!
will