netdev - Re: [PATCH 4/5] kprobes: Do not expose probe addresses to non-CAP

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Message-Id: <20200710230921.7199e51fa19a7dce53823835@kernel.org>
Date:   Fri, 10 Jul 2020 23:09:21 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Dominik Czarnota <dominik.czarnota@...ilofbits.com>,
        stable@...r.kernel.org, Jessica Yu <jeyu@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        KP Singh <kpsingh@...omium.org>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Will Deacon <will@...nel.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Marc Zyngier <maz@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Matteo Croce <mcroce@...hat.com>,
        Edward Cree <ecree@...arflare.com>,
        Nicolas Dichtel <nicolas.dichtel@...nd.com>,
        Alexander Lobakin <alobakin@...nk.ru>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Ingo Molnar <mingo@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] kprobes: Do not expose probe addresses to
 non-CAP_SYSLOG

On Thu,  2 Jul 2020 16:26:37 -0700
Kees Cook <keescook@...omium.org> wrote:

> The kprobe show() functions were using "current"'s creds instead
> of the file opener's creds for kallsyms visibility. Fix to use
> seq_file->file->f_cred.

This looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thanks!

> 
> Cc: stable@...r.kernel.org
> Fixes: 81365a947de4 ("kprobes: Show address of kprobes if kallsyms does")
> Fixes: ffb9bd68ebdb ("kprobes: Show blacklist addresses as same as kallsyms does")
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
>  kernel/kprobes.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index d4de217e4a91..2e97febeef77 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2448,7 +2448,7 @@ static void report_probe(struct seq_file *pi, struct kprobe *p,
>  	else
>  		kprobe_type = "k";
>  
> -	if (!kallsyms_show_value(current_cred()))
> +	if (!kallsyms_show_value(pi->file->f_cred))
>  		addr = NULL;
>  
>  	if (sym)
> @@ -2540,7 +2540,7 @@ static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
>  	 * If /proc/kallsyms is not showing kernel address, we won't
>  	 * show them here either.
>  	 */
> -	if (!kallsyms_show_value(current_cred()))
> +	if (!kallsyms_show_value(m->file->f_cred))
>  		seq_printf(m, "0x%px-0x%px\t%ps\n", NULL, NULL,
>  			   (void *)ent->start_addr);
>  	else
> -- 
> 2.25.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>