linux-kernel - Re: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CADyE4xHw_eikPhgsVuOwpi34vF22_i0MhVaQac0bVvKZ6hLqdw@mail.gmail.com>
Date:   Wed, 8 May 2019 02:22:26 +0900
From:   Masami Hiramatsu <masami.hiramatsu@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Nicolai Stange <nstange@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Shuah Khan <shuah@...nel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Juergen Gross <jgross@...e.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nayna Jain <nayna@...ux.ibm.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Joerg Roedel <jroedel@...e.de>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>, stable <stable@...r.kernel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions

2019年5月7日(火) 21:54 Steven Rostedt <rostedt@...dmis.org>:
>
> On Tue, 7 May 2019 14:41:31 +0200
> Peter Zijlstra <peterz@...radead.org> wrote:
>
> > > Kprobes sets the FTRACE_OPS_FL_IPMODIFY flag, thus
> > > they can never be put at the same location that is being live patched.
> >
> > OK, so do we want to allow kprobes that also modify regs->sp ? Because
> > then we need to change these trampolines a bit.
> >
> > I'd prefer not to allow kprobes this.
>
> I believe no kprobe changes sp, because it would have had the same
> issues we are trying to solve now. And even though we are changing
> things to allow it, it's not a regression to keep kprobes from doing it.

No, kprobes doesn't allow to change sp. At this moment we can't change
"&regs->sp" since it is just a value :)
kprobes user (e.g. function fault-injection) will change regs->ip,
that is why kprobes sets IPMODIFY flag.

Thank you,

-- 
Masami Hiramatsu
mailto:masami.hiramatsu@...il.com