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
prev parent 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]
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