Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1511651 > unrolled thread

[PATCH] coredump: clarify "unsafe core_pattern" warning

Back to article view | Back to linux.kernel

Contents

  [PATCH] coredump: clarify "unsafe core_pattern" warning Alexey Dobriyan <adobriyan@gmail.com> - 2016-10-29 15:30 +0200
    Re: [PATCH] coredump: clarify "unsafe core_pattern" warning Kees Cook <keescook@chromium.org> - 2016-10-29 18:10 +0200

#1511651 — [PATCH] coredump: clarify "unsafe core_pattern" warning

I was amused to find "unsafe core_pattern" warning having these lines
in /etc/sysctl.conf:

	fs.suid_dumpable=2
	kernel.core_pattern=/core/core-%e-%p-%E
	kernel.core_uses_pid=0

Turns out kernel is formally right. Default core_pattern is just "core",
which doesn't qualify for secure path while setting suid.dumpable.

Hint admins about solution, clarify sysctl names, delete unnecessary '\'
characters (string literals are concatenated regardless) and reformat
for easier grepping.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

 kernel/sysctl.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

commit ba93b14a4f61e4563134abab5d81bb8b53c60df9
Author: Alexey Dobriyan <adobriyan@gmail.com>
Date:   Sat Oct 29 18:13:57 2016 +0300

    kernel.core_dump

--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2403,9 +2403,11 @@ static void validate_coredump_safety(void)
 #ifdef CONFIG_COREDUMP
 	if (suid_dumpable == SUID_DUMP_ROOT &&
 	    core_pattern[0] != '/' && core_pattern[0] != '|') {
-		printk(KERN_WARNING "Unsafe core_pattern used with "\
-			"suid_dumpable=2. Pipe handler or fully qualified "\
-			"core dump path required.\n");
+		printk(KERN_WARNING
+"Unsafe core_pattern used with fs.suid_dumpable=2.\n"
+"Pipe handler or fully qualified core dump path required.\n"
+"Set kernel.core_pattern before fs.suid_dumpable.\n"
+		);
 	}
 #endif
 }

[toc] | [next] | [standalone]

#1511829

On Sat, Oct 29, 2016 at 8:21 AM, Alexey Dobriyan <adobriyan@gmail.com> wrote:
> I was amused to find "unsafe core_pattern" warning having these lines
> in /etc/sysctl.conf:
>
>         fs.suid_dumpable=2
>         kernel.core_pattern=/core/core-%e-%p-%E
>         kernel.core_uses_pid=0
>
> Turns out kernel is formally right. Default core_pattern is just "core",
> which doesn't qualify for secure path while setting suid.dumpable.
>
> Hint admins about solution, clarify sysctl names, delete unnecessary '\'
> characters (string literals are concatenated regardless) and reformat
> for easier grepping.
>
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>

Ah, yes, order of operations mattered. :) I like the rephrasing, thanks!

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>
>  kernel/sysctl.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> commit ba93b14a4f61e4563134abab5d81bb8b53c60df9
> Author: Alexey Dobriyan <adobriyan@gmail.com>
> Date:   Sat Oct 29 18:13:57 2016 +0300
>
>     kernel.core_dump
>
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2403,9 +2403,11 @@ static void validate_coredump_safety(void)
>  #ifdef CONFIG_COREDUMP
>         if (suid_dumpable == SUID_DUMP_ROOT &&
>             core_pattern[0] != '/' && core_pattern[0] != '|') {
> -               printk(KERN_WARNING "Unsafe core_pattern used with "\
> -                       "suid_dumpable=2. Pipe handler or fully qualified "\
> -                       "core dump path required.\n");
> +               printk(KERN_WARNING
> +"Unsafe core_pattern used with fs.suid_dumpable=2.\n"
> +"Pipe handler or fully qualified core dump path required.\n"
> +"Set kernel.core_pattern before fs.suid_dumpable.\n"
> +               );
>         }
>  #endif
>  }



-- 
Kees Cook
Nexus Security

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web