linux-kernel - Re: [PATCH v3 08/17] kprobes: fix compilation without CONFIG

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Message-ID: <201910312055.B551A6CB4@keescook>
Date:   Thu, 31 Oct 2019 20:55:25 -0700
From:   Kees Cook <keescook@...omium.org>
To:     samitolvanen@...gle.com
Cc:     Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Dave Martin <Dave.Martin@....com>,
        Laura Abbott <labbott@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Jann Horn <jannh@...gle.com>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        clang-built-linux@...glegroups.com,
        kernel-hardening@...ts.openwall.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 08/17] kprobes: fix compilation without
 CONFIG_KRETPROBES

On Thu, Oct 31, 2019 at 09:46:28AM -0700, samitolvanen@...gle.com wrote:
> kprobe_on_func_entry and arch_kprobe_on_func_entry need to be available
> even if CONFIG_KRETPROBES is not selected.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>

FWIW:

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> Acked-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
>  kernel/kprobes.c | 38 +++++++++++++++++++-------------------
>  1 file changed, 19 insertions(+), 19 deletions(-)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 53534aa258a6..b5e20a4669b8 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1829,6 +1829,25 @@ unsigned long __weak arch_deref_entry_point(void *entry)
>  	return (unsigned long)entry;
>  }
>  
> +bool __weak arch_kprobe_on_func_entry(unsigned long offset)
> +{
> +	return !offset;
> +}
> +
> +bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
> +{
> +	kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset);
> +
> +	if (IS_ERR(kp_addr))
> +		return false;
> +
> +	if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset) ||
> +						!arch_kprobe_on_func_entry(offset))
> +		return false;
> +
> +	return true;
> +}
> +
>  #ifdef CONFIG_KRETPROBES
>  /*
>   * This kprobe pre_handler is registered with every kretprobe. When probe
> @@ -1885,25 +1904,6 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
>  }
>  NOKPROBE_SYMBOL(pre_handler_kretprobe);
>  
> -bool __weak arch_kprobe_on_func_entry(unsigned long offset)
> -{
> -	return !offset;
> -}
> -
> -bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
> -{
> -	kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset);
> -
> -	if (IS_ERR(kp_addr))
> -		return false;
> -
> -	if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset) ||
> -						!arch_kprobe_on_func_entry(offset))
> -		return false;
> -
> -	return true;
> -}
> -
>  int register_kretprobe(struct kretprobe *rp)
>  {
>  	int ret = 0;
> -- 
> 2.24.0.rc0.303.g954a862665-goog
> 

-- 
Kees Cook