2022-07-31 09:46:51

by Gautam Menghani

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

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 <[email protected]>
---
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

2022-08-22 09:38:25

by Gautam Menghani

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

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 <[email protected]>
> ---
> 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