mailing list of musl libc
 help / color / mirror / code / Atom feed
From: Florian Weimer <fweimer@redhat.com>
To: Andrei Vagin <avagin@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>,
	 linux-arch@vger.kernel.org,
	 Linux API <linux-api@vger.kernel.org>,
	 linux-x86_64@vger.kernel.org,
	kernel-hardening@lists.openwall.com,  linux-mm@kvack.org,
	 "the arch/x86 maintainers" <x86@kernel.org>,
	 musl@lists.openwall.com, libc-alpha@sourceware.org,
	 LKML <linux-kernel@vger.kernel.org>,
	 Dave Hansen <dave.hansen@intel.com>,
	 Kees Cook <keescook@chromium.org>
Subject: [musl] Re: [PATCH v2] x86: Implement arch_prctl(ARCH_VSYSCALL_CONTROL) to disable vsyscall
Date: Mon, 27 Dec 2021 18:40:38 +0100	[thread overview]
Message-ID: <87o8520wvd.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <CANaxB-xpQr1mUUvWK5a53q49VK_HvR4Pws_NGKGa8-jihxkc_A@mail.gmail.com> (Andrei Vagin's message of "Mon, 27 Dec 2021 08:49:38 -0800")

* Andrei Vagin:

>> diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
>> index fd2ee9408e91..8eb3bcf2cedf 100644
>> --- a/arch/x86/entry/vsyscall/vsyscall_64.c
>> +++ b/arch/x86/entry/vsyscall/vsyscall_64.c
>> @@ -174,6 +174,12 @@ bool emulate_vsyscall(unsigned long error_code,
>>
>>         tsk = current;
>>
>> +       if (tsk->mm->context.vsyscall_disabled) {
>> +               warn_bad_vsyscall(KERN_WARNING, regs,
>> +                                 "vsyscall after lockout (exploit attempt?)");
>
> I don't think that we need this warning message. If we disable
> vsyscall, its address range is not differ from other addresses around
> and has to be handled the same way. For example, gVisor or any other
> sandbox engines may want to emulate vsyscall, but the kernel log will
> be full of such messages.

But with vsyscall=none, such messages are already printed.  That's why I
added the warning for the lockout case as well.

>> diff --git a/tools/testing/selftests/x86/vsyscall_control.c b/tools/testing/selftests/x86/vsyscall_control.c
>> new file mode 100644
>> index 000000000000..ee966f936c89
>> --- /dev/null
>> +++ b/tools/testing/selftests/x86/vsyscall_control.c
>
> I would move the test in a separate patch...

I can do that if it simplifies matters.

Thanks,
Florian


      reply	other threads:[~2021-12-27 17:41 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-16 18:50 [musl] " Florian Weimer
2021-12-27 16:49 ` [musl] " Andrei Vagin
2021-12-27 17:40   ` Florian Weimer [this message]

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=87o8520wvd.fsf@oldenburg.str.redhat.com \
    --to=fweimer@redhat.com \
    --cc=avagin@gmail.com \
    --cc=dave.hansen@intel.com \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=libc-alpha@sourceware.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-x86_64@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=musl@lists.openwall.com \
    --cc=x86@kernel.org \
    --subject='[musl] Re: [PATCH v2] x86: Implement arch_prctl(ARCH_VSYSCALL_CONTROL) to disable vsyscall' \
    /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

Code repositories for project(s) associated with this inbox:

	https://git.vuxu.org/mirror/musl/

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).