bpf, selftests: Fold test_current_pid_tgid_new_ns into test_progs.

Currently tests for bpf_get_ns_current_pid_tgid() are outside test_progs.
This change folds test cases into test_progs.

Changes from v11:

 - Fixed test failure is not detected.
 - Removed EXIT(3) call as it will stop test_progs execution.

Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210114141033.GA17348@localhost

Author: cneira

tools/testing/selftests/bpf/.gitignore

@@ -26,7 +26,6 @@ test_tcpnotify_user
 test_libbpf
 test_tcp_check_syncookie_user
 test_sysctl
-test_current_pid_tgid_new_ns
 xdping
 test_cpp
 *.skel.h

tools/testing/selftests/bpf/Makefile

@@ -36,8 +36,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_sock test_sockmap get_cgroup_id_user test_socket_cookie \
 	test_cgroup_storage \
 	test_netcnt test_tcpnotify_user test_sysctl \
-	test_progs-no_alu32 \
-	test_current_pid_tgid_new_ns
+	test_progs-no_alu32
 
 # Also test bpf-gcc, if present
 ifneq ($(BPF_GCC),)

tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c

@@ -1,85 +1,87 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2020 Carlos Neira cneirabustos@gmail.com */
+
+#define _GNU_SOURCE
 #include <test_progs.h>
+#include "test_ns_current_pid_tgid.skel.h"
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <sys/syscall.h>
+#include <sched.h>
+#include <sys/wait.h>
+#include <sys/mount.h>
+#include <sys/fcntl.h>
 
-struct bss {
-	__u64 dev;
-	__u64 ino;
-	__u64 pid_tgid;
-	__u64 user_pid_tgid;
-};
+#define STACK_SIZE (1024 * 1024)
+static char child_stack[STACK_SIZE];
 
-void test_ns_current_pid_tgid(void)
+static int test_current_pid_tgid(void *args)
 {
-	const char *probe_name = "raw_tracepoint/sys_enter";
-	const char *file = "test_ns_current_pid_tgid.o";
-	int err, key = 0, duration = 0;
-	struct bpf_link *link = NULL;
-	struct bpf_program *prog;
-	struct bpf_map *bss_map;
-	struct bpf_object *obj;
-	struct bss bss;
+	struct test_ns_current_pid_tgid__bss  *bss;
+	struct test_ns_current_pid_tgid *skel;
+	int err = -1, duration = 0;
+	pid_t tgid, pid;
 	struct stat st;
-	__u64 id;
-
-	obj = bpf_object__open_file(file, NULL);
-	if (CHECK(IS_ERR(obj), "obj_open", "err %ld\n", PTR_ERR(obj)))
-		return;
 
-	err = bpf_object__load(obj);
-	if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
+	skel = test_ns_current_pid_tgid__open_and_load();
+	if (CHECK(!skel, "skel_open_load", "failed to load skeleton\n"))
 		goto cleanup;
 
-	bss_map = bpf_object__find_map_by_name(obj, "test_ns_.bss");
-	if (CHECK(!bss_map, "find_bss_map", "failed\n"))
+	pid = syscall(SYS_gettid);
+	tgid = getpid();
+
+	err = stat("/proc/self/ns/pid", &st);
+	if (CHECK(err, "stat", "failed /proc/self/ns/pid: %d\n", err))
 		goto cleanup;
 
-	prog = bpf_object__find_program_by_title(obj, probe_name);
-	if (CHECK(!prog, "find_prog", "prog '%s' not found\n",
-		  probe_name))
+	bss = skel->bss;
+	bss->dev = st.st_dev;
+	bss->ino = st.st_ino;
+	bss->user_pid = 0;
+	bss->user_tgid = 0;
+
+	err = test_ns_current_pid_tgid__attach(skel);
+	if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
 		goto cleanup;
 
-	memset(&bss, 0, sizeof(bss));
-	pid_t tid = syscall(SYS_gettid);
-	pid_t pid = getpid();
+	/* trigger tracepoint */
+	usleep(1);
+	ASSERT_EQ(bss->user_pid, pid, "pid");
+	ASSERT_EQ(bss->user_tgid, tgid, "tgid");
+	err = 0;
 
-	id = (__u64) tid << 32 | pid;
-	bss.user_pid_tgid = id;
+cleanup:
+	 test_ns_current_pid_tgid__destroy(skel);
 
-	if (CHECK_FAIL(stat("/proc/self/ns/pid", &st))) {
-		perror("Failed to stat /proc/self/ns/pid");
-		goto cleanup;
-	}
+	return err;
+}
 
-	bss.dev = st.st_dev;
-	bss.ino = st.st_ino;
+static void test_ns_current_pid_tgid_new_ns(void)
+{
+	int wstatus, duration = 0;
+	pid_t cpid;
 
-	err = bpf_map_update_elem(bpf_map__fd(bss_map), &key, &bss, 0);
-	if (CHECK(err, "setting_bss", "failed to set bss : %d\n", err))
-		goto cleanup;
+	/* Create a process in a new namespace, this process
+	 * will be the init process of this new namespace hence will be pid 1.
+	 */
+	cpid = clone(test_current_pid_tgid, child_stack + STACK_SIZE,
+		     CLONE_NEWPID | SIGCHLD, NULL);
 
-	link = bpf_program__attach_raw_tracepoint(prog, "sys_enter");
-	if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n",
-		  PTR_ERR(link))) {
-		link = NULL;
-		goto cleanup;
-	}
+	if (CHECK(cpid == -1, "clone", strerror(errno)))
+		return;
 
-	/* trigger some syscalls */
-	usleep(1);
+	if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", strerror(errno)))
+		return;
 
-	err = bpf_map_lookup_elem(bpf_map__fd(bss_map), &key, &bss);
-	if (CHECK(err, "set_bss", "failed to get bss : %d\n", err))
-		goto cleanup;
+	if (CHECK(WEXITSTATUS(wstatus) != 0, "newns_pidtgid", "failed"))
+		return;
+}
 
-	if (CHECK(id != bss.pid_tgid, "Compare user pid/tgid vs. bpf pid/tgid",
-		  "User pid/tgid %llu BPF pid/tgid %llu\n", id, bss.pid_tgid))
-		goto cleanup;
-cleanup:
-	bpf_link__destroy(link);
-	bpf_object__close(obj);
+void test_ns_current_pid_tgid(void)
+{
+	if (test__start_subtest("ns_current_pid_tgid_root_ns"))
+		test_current_pid_tgid(NULL);
+	if (test__start_subtest("ns_current_pid_tgid_new_ns"))
+		test_ns_current_pid_tgid_new_ns();
 }

tools/testing/selftests/bpf/progs/test_ns_current_pid_tgid.c

@@ -5,31 +5,21 @@
 #include <stdint.h>
 #include <bpf/bpf_helpers.h>
 
-static volatile struct {
-	__u64 dev;
-	__u64 ino;
-	__u64 pid_tgid;
-	__u64 user_pid_tgid;
-} res;
+__u64 user_pid = 0;
+__u64 user_tgid = 0;
+__u64 dev = 0;
+__u64 ino = 0;
 
-SEC("raw_tracepoint/sys_enter")
-int trace(void *ctx)
+SEC("tracepoint/syscalls/sys_enter_nanosleep")
+int handler(const void *ctx)
 {
-	__u64  ns_pid_tgid, expected_pid;
 	struct bpf_pidns_info nsdata;
-	__u32 key = 0;
 
-	if (bpf_get_ns_current_pid_tgid(res.dev, res.ino, &nsdata,
-		   sizeof(struct bpf_pidns_info)))
+	if (bpf_get_ns_current_pid_tgid(dev, ino, &nsdata, sizeof(struct bpf_pidns_info)))
 		return 0;
 
-	ns_pid_tgid = (__u64)nsdata.tgid << 32 | nsdata.pid;
-	expected_pid = res.user_pid_tgid;
-
-	if (expected_pid != ns_pid_tgid)
-		return 0;
-
-	res.pid_tgid = ns_pid_tgid;
+	user_pid = nsdata.pid;
+	user_tgid = nsdata.tgid;
 
 	return 0;
 }