linux-kernel - Re: [PATCH v3 4/8] fprobe: rethook: Use ftrace

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: <CABRcYmK2-jiDOrTqjgg41t0T2-Uf1jbsuiV0xT37M=5cVCB+Zw@mail.gmail.com>
Date:   Thu, 17 Aug 2023 10:57:40 +0200
From:   Florent Revest <revest@...omium.org>
To:     "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-trace-kernel@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        bpf <bpf@...r.kernel.org>, Sven Schnelle <svens@...ux.ibm.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alan Maguire <alan.maguire@...cle.com>,
        Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v3 4/8] fprobe: rethook: Use ftrace_regs in fprobe exit
 handler and rethook

On Sat, Aug 12, 2023 at 7:37 AM Masami Hiramatsu (Google)
<mhiramat@...nel.org> wrote:
>
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 976fd594b446..d56304276318 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -57,6 +57,13 @@ config HAVE_DYNAMIC_FTRACE_WITH_ARGS
>          This allows for use of ftrace_regs_get_argument() and
>          ftrace_regs_get_stack_pointer().
>
> +config HAVE_PT_REGS_TO_FTRACE_REGS_CAST
> +       bool
> +       help
> +        If this is set, the memory layout of the ftrace_regs data structure
> +        is the same as the pt_regs. So the pt_regs is possible to be casted
> +        to ftrace_regs.

What would you think of introducing a:

#ifdef HAVE_PT_REGS_TO_FTRACE_REGS_CAST
static_assert(sizeof(struct pt_regs) == sizeof(struct ftrace_regs);
#endif // HAVE_PT_REGS_TO_FTRACE_REGS_CAST

somewhere in ftrace.h just as a small extra safety net ? It doesn't
exactly guarantee all we want but it should give an early warning of
mistakes.