2020-10-30 12:43:00

by Mickaël Salaün

Subject: [PATCH v1 2/2] seccomp: Set PF_SUPERPRIV when checking capability

From: Mickaël Salaün <[email protected]>

Replace the use of security_capable(current_cred(), ...) with
ns_capable_noaudit() which set PF_SUPERPRIV.

Since commit 98f368e9e263 ("kernel: Add noaudit variant of
ns_capable()"), a new ns_capable_noaudit() helper is available. Let's
use it!

Cc: Jann Horn <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Tyler Hicks <[email protected]>
Cc: Will Drewry <[email protected]>
Cc: [email protected]
Fixes: e2cfabdfd075 ("seccomp: add system call filtering using BPF")
Signed-off-by: Mickaël Salaün <[email protected]>
---
kernel/seccomp.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 8ad7a293255a..53a7d1512dd7 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -38,7 +38,7 @@
#include <linux/filter.h>
#include <linux/pid.h>
#include <linux/ptrace.h>
-#include <linux/security.h>
+#include <linux/capability.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>
#include <linux/anon_inodes.h>
@@ -558,8 +558,7 @@ static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
* behavior of privileged children.
*/
if (!task_no_new_privs(current) &&
- security_capable(current_cred(), current_user_ns(),
- CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) != 0)
+ !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
return ERR_PTR(-EACCES);

/* Allocate a new seccomp_filter */
--
2.28.0

2020-10-30 15:36:41

by Jann Horn

Subject: Re: [PATCH v1 2/2] seccomp: Set PF_SUPERPRIV when checking capability

On Fri, Oct 30, 2020 at 1:39 PM Mickaël Salaün <[email protected]> wrote:
> Replace the use of security_capable(current_cred(), ...) with
> ns_capable_noaudit() which set PF_SUPERPRIV.
>
> Since commit 98f368e9e263 ("kernel: Add noaudit variant of
> ns_capable()"), a new ns_capable_noaudit() helper is available. Let's
> use it!
>
> Cc: Jann Horn <[email protected]>
> Cc: Kees Cook <[email protected]>
> Cc: Tyler Hicks <[email protected]>
> Cc: Will Drewry <[email protected]>
> Cc: [email protected]
> Fixes: e2cfabdfd075 ("seccomp: add system call filtering using BPF")
> Signed-off-by: Mickaël Salaün <[email protected]>

Reviewed-by: Jann Horn <[email protected]>