linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Will Drewry <wad@chromium.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-doc@vger.kernel.org, kernel-hardening@lists.openwall.com,
	netdev@vger.kernel.org, x86@kernel.org, arnd@arndb.de,
	davem@davemloft.net, hpa@zytor.com, mingo@redhat.com,
	peterz@infradead.org, rdunlap@xenotime.net,
	mcgrathr@chromium.org, tglx@linutronix.de, luto@mit.edu,
	eparis@redhat.com, serge.hallyn@canonical.com, djm@mindrot.org,
	scarybeasts@gmail.com, indan@nul.nu, pmoore@redhat.com,
	akpm@linux-foundation.org, corbet@lwn.net,
	eric.dumazet@gmail.com, markus@chromium.org,
	coreyb@linux.vnet.ibm.com, keescook@chromium.org
Subject: Re: [PATCH v11 08/12] signal, x86: add SIGSYS info and make it synchronous.
Date: Tue, 28 Feb 2012 11:06:54 -0600	[thread overview]
Message-ID: <CABqD9hbOi7Hk8X3zwewmvU1QTLQ_XDM140oS37XaZNtQajbDsQ@mail.gmail.com> (raw)
In-Reply-To: <20120228160257.GB3664@redhat.com>

On Tue, Feb 28, 2012 at 10:02 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> On 02/27, Will Drewry wrote:
>>
>> On Mon, Feb 27, 2012 at 11:22 AM, Oleg Nesterov <oleg@redhat.com> wrote:
>> > On 02/24, Will Drewry wrote:
>> >>
>> >> To ensure that SIGSYS delivery occurs on return from the triggering
>> >> system call, SIGSYS is added to the SYNCHRONOUS_MASK macro.
>> >
>> > Hmm. Can't understand... please help.
>> >
>> >>  #define SYNCHRONOUS_MASK \
>> >>       (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
>> >> -      sigmask(SIGTRAP) | sigmask(SIGFPE))
>> >> +      sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
>> >
>> > Why?
>> >
>> > SYNCHRONOUS_MASK just tells dequeue_signal() "pick them first".
>> > This is needed to make sure that the handler for, say SIGSEGV,
>> > can use ucontext->ip as a faulting addr.
>>
>> I think that Roland covered this.  (Since the syscall_rollback was
>> called it's nice to let our handler get first go.)
>
> OK, except I do not really understand the "our handler get first go".

Err I meant "gets to go first".

> Suppose SIGSYS "races" with the pending SIGHUP. With this change
> the caller for SIGHUP will be called first. But yes, setup_frame()
> will be called for SIGSYS first. Hopefully this is what you want.

I believe it is.  I just want ucontext_t to be properly populate since
the registers were just rolled back for it.

>> > But seccomp adds info->si_call_addr, this looks unneeded.
>>
>> True enough.  I can drop it.
>
> Hmm. I meant, the change in SYNCHRONOUS_MASK looks unneeded. Please
> keep ->si_call_addr, it is much more convenient than ucontext_t in
> userspace.

Sorry for the confusion

>> It'd only be useful if the SIGSYS wasn't
>> being forced and the signal was being handled without ucontext_t
>> access.
>
> No, force_ doesn't make any difference in this sense...

I guess I was thinking about users of signalfd wanting the call site
but force_ avoids it being blockable so that seems largely irrelevant
at present.

> In short, the patch looks fine to me, but if you resend it may be
> you can update the changelog.

Thanks! I will try to clarify the changelog.
will

  reply	other threads:[~2012-02-28 17:07 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-25  3:21 [PATCH v11 01/12] sk_run_filter: add support for custom load_pointer Will Drewry
2012-02-25  3:21 ` [PATCH v11 02/12] net/compat.c,linux/filter.h: share compat_sock_fprog Will Drewry
2012-02-25  3:21 ` [PATCH v11 03/12] seccomp: kill the seccomp_t typedef Will Drewry
2012-02-25  3:21 ` [PATCH v11 04/12] asm/syscall.h: add syscall_get_arch Will Drewry
2012-02-25  3:21 ` [PATCH v11 05/12] arch/x86: add syscall_get_arch to syscall.h Will Drewry
2012-02-25  3:21 ` [PATCH v11 06/12] seccomp: add system call filtering using BPF Will Drewry
2012-02-26 20:28   ` Kees Cook
2012-02-27 16:23     ` Will Drewry
2012-02-27 16:49       ` Eric Paris
2012-02-27 18:55         ` Kees Cook
2012-02-27 19:25           ` Eric Paris
2012-02-27 20:00             ` Kees Cook
2012-02-27 20:34               ` Eric Paris
2012-02-27 20:49                 ` Kees Cook
2012-02-27 17:09   ` Oleg Nesterov
2012-02-27 19:54     ` Will Drewry
2012-02-27 20:15       ` Kees Cook
2012-02-28 15:13       ` Oleg Nesterov
2012-02-28 17:18         ` Will Drewry
2012-02-28  6:51   ` Indan Zupancic
2012-02-28  7:52     ` Kees Cook
2012-02-28 17:17     ` Will Drewry
2012-02-28 17:47       ` Markus Gutschke
2012-02-25  3:21 ` [PATCH v11 07/12] seccomp: add SECCOMP_RET_ERRNO Will Drewry
2012-02-25 20:20   ` Kees Cook
2012-02-27 16:22     ` Will Drewry
2012-02-27 17:11   ` Oleg Nesterov
2012-02-27 18:09     ` Kees Cook
2012-02-27 18:14       ` Oleg Nesterov
2012-02-27 18:35         ` Andrew Lutomirski
2012-02-27 19:14           ` Kees Cook
2012-02-27 19:54             ` Will Drewry
2012-02-25  3:21 ` [PATCH v11 08/12] signal, x86: add SIGSYS info and make it synchronous Will Drewry
2012-02-27 17:22   ` Oleg Nesterov
2012-02-27 17:34     ` Roland McGrath
2012-02-27 18:08       ` Oleg Nesterov
2012-02-27 20:24     ` Will Drewry
2012-02-28 16:02       ` Oleg Nesterov
2012-02-28 17:06         ` Will Drewry [this message]
2012-02-25  3:21 ` [PATCH v11 09/12] seccomp: Add SECCOMP_RET_TRAP Will Drewry
2012-02-25  3:21 ` [PATCH v11 10/12] ptrace,seccomp: Add PTRACE_SECCOMP support Will Drewry
2012-02-27 17:54   ` Oleg Nesterov
2012-02-27 19:47     ` Will Drewry
2012-02-28 16:43       ` Oleg Nesterov
2012-02-28 17:04         ` Will Drewry
2012-02-28 18:34           ` Will Drewry
2012-02-29 16:14             ` Oleg Nesterov
2012-02-29 16:33               ` Will Drewry
2012-02-29 17:09                 ` Oleg Nesterov
2012-02-29 17:41                   ` Roland McGrath
2012-02-29 17:51                     ` Will Drewry
2012-02-25  3:21 ` [PATCH v11 11/12] x86: Enable HAVE_ARCH_SECCOMP_FILTER Will Drewry
2012-02-25  3:21 ` [PATCH v11 12/12] Documentation: prctl/seccomp_filter Will Drewry

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CABqD9hbOi7Hk8X3zwewmvU1QTLQ_XDM140oS37XaZNtQajbDsQ@mail.gmail.com \
    --to=wad@chromium.org \
    --cc=akpm@linux-foundation.org \
    --cc=arnd@arndb.de \
    --cc=corbet@lwn.net \
    --cc=coreyb@linux.vnet.ibm.com \
    --cc=davem@davemloft.net \
    --cc=djm@mindrot.org \
    --cc=eparis@redhat.com \
    --cc=eric.dumazet@gmail.com \
    --cc=hpa@zytor.com \
    --cc=indan@nul.nu \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@mit.edu \
    --cc=markus@chromium.org \
    --cc=mcgrathr@chromium.org \
    --cc=mingo@redhat.com \
    --cc=netdev@vger.kernel.org \
    --cc=oleg@redhat.com \
    --cc=peterz@infradead.org \
    --cc=pmoore@redhat.com \
    --cc=rdunlap@xenotime.net \
    --cc=scarybeasts@gmail.com \
    --cc=serge.hallyn@canonical.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).