Re: [PATCH bpf-next 1/4] selftests/bpf: convert get_current_cgroup_id_user to test_progs

On 31/07/2024 11:38, Alexis Lothoré (eBPF Foundation) wrote:

get_current_cgroup_id_user allows testing for bpf_get_current_cgroup_id() bpf API but is not integrated into test_progs, and so is not tested automatically in CI.

Convert it to the test_progs framework to allow running it automatically. The most notable differences with the old test are the following:

• the new test relies on autoattach instead of manually hooking/enabling the targeted tracepoint through perf_event, which reduces quite a lot the test code size
• sleep duration passed to nanosleep syscall has been reduced to its minimum to not impact overall CI duration (we only care about the syscall being properly triggered, not about the passed duration)

Signed-off-by: Alexis Lothoré (eBPF Foundation) alexis.lothore@bootlin.com

Nice work! Two small suggestions below..

---

The new test_progs part has been tested in a local qemu environment:

./test_progs -a cgroup_get_current_cgroup_id 47 cgroup_get_current_cgroup_id:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

---

tools/testing/selftests/bpf/.gitignore | 1 - tools/testing/selftests/bpf/Makefile | 3 +- tools/testing/selftests/bpf/get_cgroup_id_user.c | 151 --------------------- .../bpf/prog_tests/cgroup_get_current_cgroup_id.c | 58 ++++++++ 4 files changed, 59 insertions(+), 154 deletions(-)

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore index 4e4aae8aa7ec..108eb10626b9 100644 --- a/tools/testing/selftests/bpf/.gitignore +++ b/tools/testing/selftests/bpf/.gitignore @@ -20,7 +20,6 @@ test_sock urandom_read test_sockmap test_lirc_mode2_user -get_cgroup_id_user test_skb_cgroup_id_user test_cgroup_storage test_flow_dissector diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 1d7a62e7deff..8d8483f81009 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -68,7 +68,7 @@ endif # Order correspond to 'make run_tests' order TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \ test_dev_cgroup \

• test_sock test_sockmap get_cgroup_id_user \

• test_sock test_sockmap \ test_cgroup_storage \ test_tcpnotify_user test_sysctl \ test_progs-no_alu32

@@ -297,7 +297,6 @@ $(OUTPUT)/test_skb_cgroup_id_user: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_sock: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_sockmap: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_tcpnotify_user: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(TRACE_HELPERS) -$(OUTPUT)/get_cgroup_id_user: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_cgroup_storage: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_sock_fields: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(OUTPUT)/test_sysctl: $(CGROUP_HELPERS) $(TESTING_HELPERS) diff --git a/tools/testing/selftests/bpf/get_cgroup_id_user.c b/tools/testing/selftests/bpf/get_cgroup_id_user.c deleted file mode 100644 index aefd83ebdcd7..000000000000 --- a/tools/testing/selftests/bpf/get_cgroup_id_user.c +++ /dev/null @@ -1,151 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -// Copyright (c) 2018 Facebook

-#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <errno.h> -#include <fcntl.h> -#include <syscall.h> -#include <unistd.h> -#include <linux/perf_event.h> -#include <sys/ioctl.h> -#include <sys/time.h> -#include <sys/types.h> -#include <sys/stat.h>

-#include <linux/bpf.h> -#include <bpf/bpf.h> -#include <bpf/libbpf.h>

-#include "cgroup_helpers.h" -#include "testing_helpers.h"

-#define CHECK(condition, tag, format...) ({ \

• int __ret = !!(condition); \
• if (__ret) { \

• printf("%s:FAIL:%s ", __func__, tag);	\
  

• printf(format);				\
  

• } else { \

• printf("%s:PASS:%s\n", __func__, tag);	\
  

• } \
• __ret; \

-})

-static int bpf_find_map(const char *test, struct bpf_object *obj,

• 	const char *name)
  

-{

• struct bpf_map *map;
• map = bpf_object__find_map_by_name(obj, name);
• if (!map)

• return -1;
  

• return bpf_map__fd(map);

-}

-#define TEST_CGROUP "/test-bpf-get-cgroup-id/"

-int main(int argc, char **argv) -{

• const char *probe_name = "syscalls/sys_enter_nanosleep";
• const char *file = "get_cgroup_id_kern.bpf.o";
• int err, bytes, efd, prog_fd, pmu_fd;
• int cgroup_fd, cgidmap_fd, pidmap_fd;
• struct perf_event_attr attr = {};
• struct bpf_object *obj;
• __u64 kcgid = 0, ucgid;
• __u32 key = 0, pid;
• int exit_code = 1;
• char buf[256];
• const struct timespec req = {

• .tv_sec = 1,
  

• .tv_nsec = 0,
  

• };
• cgroup_fd = cgroup_setup_and_join(TEST_CGROUP);
• if (CHECK(cgroup_fd < 0, "cgroup_setup_and_join", "err %d errno %d\n", cgroup_fd, errno))

• return 1;
  

• /* Use libbpf 1.0 API mode */
• libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
• err = bpf_prog_test_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
• if (CHECK(err, "bpf_prog_test_load", "err %d errno %d\n", err, errno))

• goto cleanup_cgroup_env;
  

• cgidmap_fd = bpf_find_map(__func__, obj, "cg_ids");
• if (CHECK(cgidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",

•   cgidmap_fd, errno))
  

• goto close_prog;
  

• pidmap_fd = bpf_find_map(__func__, obj, "pidmap");
• if (CHECK(pidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",

•   pidmap_fd, errno))
  

• goto close_prog;
  

• pid = getpid();
• bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
• if (access("/sys/kernel/tracing/trace", F_OK) == 0) {

• snprintf(buf, sizeof(buf),
  

• 	 "/sys/kernel/tracing/events/%s/id", probe_name);
  

• } else {

• snprintf(buf, sizeof(buf),
  

• 	 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
  

• }
• efd = open(buf, O_RDONLY, 0);
• if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))

• goto close_prog;
  

• bytes = read(efd, buf, sizeof(buf));
• close(efd);
• if (CHECK(bytes <= 0 || bytes >= sizeof(buf), "read",

•   "bytes %d errno %d\n", bytes, errno))
  

• goto close_prog;
  

• attr.config = strtol(buf, NULL, 0);
• attr.type = PERF_TYPE_TRACEPOINT;
• attr.sample_type = PERF_SAMPLE_RAW;
• attr.sample_period = 1;
• attr.wakeup_events = 1;
• /* attach to this pid so the all bpf invocations will be in the

• * cgroup associated with this pid.
  

• */
  

• pmu_fd = syscall(__NR_perf_event_open, &attr, getpid(), -1, -1, 0);
• if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n", pmu_fd,

•   errno))
  

• goto close_prog;
  

• err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
• if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n", err,

•   errno))
  

• goto close_pmu;
  

• err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
• if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n", err,

•   errno))
  

• goto close_pmu;
  

• /* trigger some syscalls */
• syscall(__NR_nanosleep, &req, NULL);
• err = bpf_map_lookup_elem(cgidmap_fd, &key, &kcgid);
• if (CHECK(err, "bpf_map_lookup_elem", "err %d errno %d\n", err, errno))

• goto close_pmu;
  

• ucgid = get_cgroup_id(TEST_CGROUP);
• if (CHECK(kcgid != ucgid, "compare_cgroup_id",

•   "kern cgid %llx user cgid %llx", kcgid, ucgid))
  

• goto close_pmu;
  

• exit_code = 0;
• printf("%s:PASS\n", argv[0]);

-close_pmu:

• close(pmu_fd);

-close_prog:

• bpf_object__close(obj);

-cleanup_cgroup_env:

• cleanup_cgroup_environment();
• return exit_code;

-} diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_get_current_cgroup_id.c b/tools/testing/selftests/bpf/prog_tests/cgroup_get_current_cgroup_id.c new file mode 100644 index 000000000000..dd8835a63a00 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_get_current_cgroup_id.c @@ -0,0 +1,58 @@ +// SPDX-License-Identifier: GPL-2.0

+#include <sys/stat.h> +#include <sys/sysmacros.h> +#include "test_progs.h" +#include "cgroup_helpers.h" +#include "get_cgroup_id_kern.skel.h"

+#define TEST_CGROUP "/test-bpf-get-cgroup-id/"

+void test_cgroup_get_current_cgroup_id(void) +{

• struct get_cgroup_id_kern *skel;
• const struct timespec req = {

• .tv_sec = 0,
  

• .tv_nsec = 1,
  

• };
• __u64 kcgid, ucgid;
• int cgroup_fd;
• int key = 0;
• int pid;
• cgroup_fd = cgroup_setup_and_join(TEST_CGROUP);
• if (!ASSERT_OK_FD(cgroup_fd, "cgroup switch"))

• return;
  

• skel = get_cgroup_id_kern__open_and_load();
• if (!ASSERT_OK_PTR(skel, "load program"))

• goto cleanup_cgroup;
  

• if (!ASSERT_OK(get_cgroup_id_kern__attach(skel), "attach bpf program"))

• goto cleanup_progs;
  

• pid = getpid();
• if (!ASSERT_OK(bpf_map__update_elem(skel->maps.pidmap, &key,

• 			    sizeof(key), &pid, sizeof(pid), 0),
  

•        "write pid"))
  

• goto cleanup_progs;
  

I think it would be worth using a global variable in the BPF program my_pid, and setting skel->bss->my_pid here as other more up-to-date tests do (example progs/test_usdt.c, prog_tests/usdt.c). No need for a separate map anymore.

• /* trigger the syscall on which is attached the tested prog */
• if (!ASSERT_OK(syscall(__NR_nanosleep, &req, NULL), "nanosleep"))

• goto cleanup_progs;
  

• if (!ASSERT_OK(bpf_map__lookup_elem(skel->maps.cg_ids, &key,

• 			    sizeof(key), &kcgid, sizeof(kcgid),
  

• 			    0),
  

•        "read bpf cgroup id"))
  

• goto cleanup_progs;
  

ditto here, cg_ids could be a global var cg_id that the bpf prog sets and we check here via skel->bss->cg_id.

• ucgid = get_cgroup_id(TEST_CGROUP);
• ASSERT_EQ(kcgid, ucgid, "compare cgroup ids");

+cleanup_progs:

• get_cgroup_id_kern__destroy(skel);

+cleanup_cgroup:

• cleanup_cgroup_environment();

+}