Re: [PATCH] selftests/seccomp: Check CAP_SYS_ADMIN capability in the test mode_filter_without_nnp

From: Gautam Menghani <gautammenghani201@gmail.com>
To: keescook@chromium.org, shuah@kernel.org, brauner@kernel.org,
	paul.walmsley@sifive.com, palmer@dabbelt.com,
	aou@eecs.berkeley.edu, guoren@kernel.org
Cc: luto@amacapital.net, wad@chromium.org,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org, bpf@vger.kernel.org,
	linux-csky@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH] selftests/seccomp: Check CAP_SYS_ADMIN capability in the test mode_filter_without_nnp
Date: Mon, 22 Aug 2022 14:19:28 +0530	[thread overview]
Message-ID: <YwNDGAVrik3DvWZf@fedora> (raw)
In-Reply-To: <20220731092529.28760-1-gautammenghani201@gmail.com>

On Sun, Jul 31, 2022 at 02:55:29PM +0530, Gautam Menghani wrote:
> In the "mode_filter_without_nnp" test in seccomp_bpf, there is currently
> a TODO which asks to check the capability CAP_SYS_ADMIN instead of euid.
> This patch adds support to check if the calling process has the flag 
> CAP_SYS_ADMIN, and also if this flag has CAP_EFFECTIVE set.
> 
> Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
> ---
>  tools/testing/selftests/seccomp/seccomp_bpf.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
> index 136df5b76319..16b0edc520ef 100644
> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
> @@ -392,6 +392,8 @@ TEST(mode_filter_without_nnp)
>  		.filter = filter,
>  	};
>  	long ret;
> +	cap_t cap = cap_get_proc();
> +	cap_flag_value_t is_cap_sys_admin = 0;
>  
>  	ret = prctl(PR_GET_NO_NEW_PRIVS, 0, NULL, 0, 0);
>  	ASSERT_LE(0, ret) {
> @@ -400,8 +402,8 @@ TEST(mode_filter_without_nnp)
>  	errno = 0;
>  	ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0);
>  	/* Succeeds with CAP_SYS_ADMIN, fails without */
> -	/* TODO(wad) check caps not euid */
> -	if (geteuid()) {
> +	cap_get_flag(cap, CAP_SYS_ADMIN, CAP_EFFECTIVE, &is_cap_sys_admin);
> +	if (!is_cap_sys_admin) {
>  		EXPECT_EQ(-1, ret);
>  		EXPECT_EQ(EACCES, errno);
>  	} else {
> -- 
> 2.34.1
> 

Hi,

Please review the above patch and let me know if any changes are required.

Thanks,
Gautam