diff options
author | Frederick Lawler <fred@cloudflare.com> | 2022-08-15 11:20:27 -0500 |
---|---|---|
committer | Paul Moore <paul@paul-moore.com> | 2022-08-16 17:39:59 -0400 |
commit | d5810139cca39cf2854728b465f8bada4a445302 (patch) | |
tree | 7a547866afe04a7158f1a5bbc600f928143bfac9 /tools/testing/selftests/bpf/prog_tests | |
parent | bpf-lsm: Make bpf_lsm_userns_create() sleepable (diff) | |
download | linux-dev-d5810139cca39cf2854728b465f8bada4a445302.tar.xz linux-dev-d5810139cca39cf2854728b465f8bada4a445302.zip |
selftests/bpf: Add tests verifying bpf lsm userns_create hook
The LSM hook userns_create was introduced to provide LSM's an
opportunity to block or allow unprivileged user namespace creation. This
test serves two purposes: it provides a test eBPF implementation, and
tests the hook successfully blocks or allows user namespace creation.
This tests 3 cases:
1. Unattached bpf program does not block unpriv user namespace
creation.
2. Attached bpf program allows user namespace creation given
CAP_SYS_ADMIN privileges.
3. Attached bpf program denies user namespace creation for a
user without CAP_SYS_ADMIN.
Acked-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Frederick Lawler <fred@cloudflare.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'tools/testing/selftests/bpf/prog_tests')
-rw-r--r-- | tools/testing/selftests/bpf/prog_tests/deny_namespace.c | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/deny_namespace.c b/tools/testing/selftests/bpf/prog_tests/deny_namespace.c new file mode 100644 index 000000000000..1bc6241b755b --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/deny_namespace.c @@ -0,0 +1,102 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <test_progs.h> +#include "test_deny_namespace.skel.h" +#include <sched.h> +#include "cap_helpers.h" +#include <stdio.h> + +static int wait_for_pid(pid_t pid) +{ + int status, ret; + +again: + ret = waitpid(pid, &status, 0); + if (ret == -1) { + if (errno == EINTR) + goto again; + + return -1; + } + + if (!WIFEXITED(status)) + return -1; + + return WEXITSTATUS(status); +} + +/* negative return value -> some internal error + * positive return value -> userns creation failed + * 0 -> userns creation succeeded + */ +static int create_user_ns(void) +{ + pid_t pid; + + pid = fork(); + if (pid < 0) + return -1; + + if (pid == 0) { + if (unshare(CLONE_NEWUSER)) + _exit(EXIT_FAILURE); + _exit(EXIT_SUCCESS); + } + + return wait_for_pid(pid); +} + +static void test_userns_create_bpf(void) +{ + __u32 cap_mask = 1ULL << CAP_SYS_ADMIN; + __u64 old_caps = 0; + + cap_enable_effective(cap_mask, &old_caps); + + ASSERT_OK(create_user_ns(), "priv new user ns"); + + cap_disable_effective(cap_mask, &old_caps); + + ASSERT_EQ(create_user_ns(), EPERM, "unpriv new user ns"); + + if (cap_mask & old_caps) + cap_enable_effective(cap_mask, NULL); +} + +static void test_unpriv_userns_create_no_bpf(void) +{ + __u32 cap_mask = 1ULL << CAP_SYS_ADMIN; + __u64 old_caps = 0; + + cap_disable_effective(cap_mask, &old_caps); + + ASSERT_OK(create_user_ns(), "no-bpf unpriv new user ns"); + + if (cap_mask & old_caps) + cap_enable_effective(cap_mask, NULL); +} + +void test_deny_namespace(void) +{ + struct test_deny_namespace *skel = NULL; + int err; + + if (test__start_subtest("unpriv_userns_create_no_bpf")) + test_unpriv_userns_create_no_bpf(); + + skel = test_deny_namespace__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel load")) + goto close_prog; + + err = test_deny_namespace__attach(skel); + if (!ASSERT_OK(err, "attach")) + goto close_prog; + + if (test__start_subtest("userns_create_bpf")) + test_userns_create_bpf(); + + test_deny_namespace__detach(skel); + +close_prog: + test_deny_namespace__destroy(skel); +} |