Re: [PATCH bpf-next 4/5] selftests/bpf: Add a cgroup prog bpf_get_ns_current_pid_tgid() test

[Martin KaFai Lau <martin.lau@linux.dev>]

On 3/7/24 3:27 PM, Yonghong Song wrote:
> Add a cgroup bpf program test where the bpf program is running
> in a pid namespace. The test is successfully:
>    #165/3   ns_current_pid_tgid/new_ns_cgrp:OK
> 
> Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
> ---
>   .../bpf/prog_tests/ns_current_pid_tgid.c      | 54 +++++++++++++++++++
>   .../bpf/progs/test_ns_current_pid_tgid.c      |  7 +++
>   2 files changed, 61 insertions(+)
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c b/tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c
> index 847d7b70e290..a307303e01ee 100644
> --- a/tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c
> +++ b/tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c
> @@ -12,6 +12,7 @@
>   #include <sys/wait.h>
>   #include <sys/mount.h>
>   #include <sys/fcntl.h>
> +#include "network_helpers.h"
>   
>   #define STACK_SIZE (1024 * 1024)
>   static char child_stack[STACK_SIZE];
> @@ -74,6 +75,50 @@ static int test_current_pid_tgid_tp(void *args)
>   	return ret;
>   }
>   
> +static int test_current_pid_tgid_cgrp(void *args)
> +{
> +	struct test_ns_current_pid_tgid__bss *bss;
> +	struct test_ns_current_pid_tgid *skel;
> +	int server_fd = -1, ret = -1, err;
> +	int cgroup_fd = *(int *)args;
> +	pid_t tgid, pid;
> +
> +	skel = test_ns_current_pid_tgid__open();
> +	if (!ASSERT_OK_PTR(skel, "test_ns_current_pid_tgid__open"))
> +		return ret;
> +
> +	bpf_program__set_autoload(skel->progs.cgroup_bind4, true);
> +
> +	err = test_ns_current_pid_tgid__load(skel);
> +	if (!ASSERT_OK(err, "test_ns_current_pid_tgid__load"))
> +		goto cleanup;
> +
> +	bss = skel->bss;
> +	if (get_pid_tgid(&pid, &tgid, bss))
> +		goto cleanup;
> +
> +	skel->links.cgroup_bind4 = bpf_program__attach_cgroup(
> +		skel->progs.cgroup_bind4, cgroup_fd);
> +	if (!ASSERT_OK_PTR(skel->links.cgroup_bind4, "bpf_program__attach_cgroup"))
> +		goto cleanup;
> +
> +	server_fd = start_server(AF_INET, SOCK_STREAM, NULL, 0, 0);

nit. This binds to ADDR_ANY. Regardless, it is a good idea to create a netns for 
this subtest. It will be one less thing to worry about when removing "serial_" 
from this test eventually. The same for the subtest in patch 5 also.

> +	if (!ASSERT_GE(server_fd, 0, "start_server"))
> +		goto cleanup;
> +
> +	if (!ASSERT_EQ(bss->user_pid, pid, "pid"))
> +		goto cleanup;
> +	if (!ASSERT_EQ(bss->user_tgid, tgid, "tgid"))
> +		goto cleanup;
> +	ret = 0;
> +
> +cleanup:
> +	if (server_fd >= 0)
> +		close(server_fd);
> +	test_ns_current_pid_tgid__destroy(skel);
> +	return ret;
> +}
> +
>   static void test_ns_current_pid_tgid_new_ns(int (*fn)(void *), void *arg)
>   {
>   	int wstatus;
> @@ -102,4 +147,13 @@ void serial_test_ns_current_pid_tgid(void)
>   		test_current_pid_tgid_tp(NULL);
>   	if (test__start_subtest("new_ns_tp"))
>   		test_ns_current_pid_tgid_new_ns(test_current_pid_tgid_tp, NULL);
> +	if (test__start_subtest("new_ns_cgrp")) {
> +		int cgroup_fd = -1;

nit. no need to "= -1;"

Other patches lgtm.

> +
> +		cgroup_fd = test__join_cgroup("/sock_addr");
> +		if (ASSERT_GE(cgroup_fd, 0, "join_cgroup")) {
> +			test_ns_current_pid_tgid_new_ns(test_current_pid_tgid_cgrp, &cgroup_fd);
> +			close(cgroup_fd);
> +		}
> +	}
>   }
> diff --git a/tools/testing/selftests/bpf/progs/test_ns_current_pid_tgid.c b/tools/testing/selftests/bpf/progs/test_ns_current_pid_tgid.c
> index aa3ec7ca16d9..d0010e698f66 100644
> --- a/tools/testing/selftests/bpf/progs/test_ns_current_pid_tgid.c
> +++ b/tools/testing/selftests/bpf/progs/test_ns_current_pid_tgid.c
> @@ -28,4 +28,11 @@ int tp_handler(const void *ctx)
>   	return 0;
>   }
>   
> +SEC("?cgroup/bind4")
> +int cgroup_bind4(struct bpf_sock_addr *ctx)
> +{
> +	get_pid_tgid();
> +	return 1;
> +}
> +
>   char _license[] SEC("license") = "GPL";