tools/testing/selftests/bpf: Add self-tests for new helper bpf_get_ns_current_pid_tgid.

Self tests added for new helper bpf_get_ns_current_pid_tgid
Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200304204157.58695-4-cneirabustos@gmail.com

tools/testing/selftests/bpf/.gitignore

@@ -31,6 +31,7 @@ test_tcp_check_syncookie_user
 test_sysctl
 test_hashmap
 test_btf_dump
+test_current_pid_tgid_new_ns
 xdping
 test_cpp
 *.skel.h

tools/testing/selftests/bpf/Makefile

@@ -32,7 +32,8 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_sock test_btf test_sockmap get_cgroup_id_user test_socket_cookie \
 	test_cgroup_storage \
 	test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
-	test_progs-no_alu32
+	test_progs-no_alu32 \
+	test_current_pid_tgid_new_ns
 
 # Also test bpf-gcc, if present
 ifneq ($(BPF_GCC),)

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

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Carlos Neira cneirabustos@gmail.com */
+#include <test_progs.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+struct bss {
+	__u64 dev;
+	__u64 ino;
+	__u64 pid_tgid;
+	__u64 user_pid_tgid;
+};
+
+void test_ns_current_pid_tgid(void)
+{
+	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 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))
+		goto cleanup;
+
+	bss_map = bpf_object__find_map_by_name(obj, "test_ns_.bss");
+	if (CHECK(!bss_map, "find_bss_map", "failed\n"))
+		goto cleanup;
+
+	prog = bpf_object__find_program_by_title(obj, probe_name);
+	if (CHECK(!prog, "find_prog", "prog '%s' not found\n",
+		  probe_name))
+		goto cleanup;
+
+	memset(&bss, 0, sizeof(bss));
+	pid_t tid = syscall(SYS_gettid);
+	pid_t pid = getpid();
+
+	id = (__u64) tid << 32 | pid;
+	bss.user_pid_tgid = id;
+
+	if (CHECK_FAIL(stat("/proc/self/ns/pid", &st))) {
+		perror("Failed to stat /proc/self/ns/pid");
+		goto cleanup;
+	}
+
+	bss.dev = st.st_dev;
+	bss.ino = st.st_ino;
+
+	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;
+
+	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;
+	}
+
+	/* trigger some syscalls */
+	usleep(1);
+
+	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(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:
+	if (!link) {
+		bpf_link__destroy(link);
+		link = NULL;
+	}
+	bpf_object__close(obj);
+}

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

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Carlos Neira cneirabustos@gmail.com */
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include <bpf/bpf_helpers.h>
+
+static volatile struct {
+	__u64 dev;
+	__u64 ino;
+	__u64 pid_tgid;
+	__u64 user_pid_tgid;
+} res;
+
+SEC("raw_tracepoint/sys_enter")
+int trace(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)))
+		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;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/test_current_pid_tgid_new_ns.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Carlos Neira cneirabustos@gmail.com */
+#define _GNU_SOURCE
+#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 "test_progs.h"
+
+#define CHECK_NEWNS(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;						\
+})
+
+struct bss {
+	__u64 dev;
+	__u64 ino;
+	__u64 pid_tgid;
+	__u64 user_pid_tgid;
+};
+
+int main(int argc, char **argv)
+{
+	pid_t pid;
+	int exit_code = 1;
+	struct stat st;
+
+	printf("Testing bpf_get_ns_current_pid_tgid helper in new ns\n");
+
+	if (stat("/proc/self/ns/pid", &st)) {
+		perror("stat failed on /proc/self/ns/pid ns\n");
+		printf("%s:FAILED\n", argv[0]);
+		return exit_code;
+	}
+
+	if (CHECK_NEWNS(unshare(CLONE_NEWPID | CLONE_NEWNS),
+			"unshare CLONE_NEWPID | CLONE_NEWNS", "error errno=%d\n", errno))
+		return exit_code;
+
+	pid = fork();
+	if (pid == -1) {
+		perror("Fork() failed\n");
+		printf("%s:FAILED\n", argv[0]);
+		return exit_code;
+	}
+
+	if (pid > 0) {
+		int status;
+
+		usleep(5);
+		waitpid(pid, &status, 0);
+		return 0;
+	} else {
+
+		pid = fork();
+		if (pid == -1) {
+			perror("Fork() failed\n");
+			printf("%s:FAILED\n", argv[0]);
+			return exit_code;
+		}
+
+		if (pid > 0) {
+			int status;
+			waitpid(pid, &status, 0);
+			return 0;
+		} else {
+			if (CHECK_NEWNS(mount("none", "/proc", NULL, MS_PRIVATE|MS_REC, NULL),
+				"Unmounting proc", "Cannot umount proc! errno=%d\n", errno))
+				return exit_code;
+
+			if (CHECK_NEWNS(mount("proc", "/proc", "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL),
+				"Mounting proc", "Cannot mount proc! errno=%d\n", errno))
+				return exit_code;
+
+			const char *probe_name = "raw_tracepoint/sys_enter";
+			const char *file = "test_ns_current_pid_tgid.o";
+			struct bpf_link *link = NULL;
+			struct bpf_program *prog;
+			struct bpf_map *bss_map;
+			struct bpf_object *obj;
+			int exit_code = 1;
+			int err, key = 0;
+			struct bss bss;
+			struct stat st;
+			__u64 id;
+
+			obj = bpf_object__open_file(file, NULL);
+			if (CHECK_NEWNS(IS_ERR(obj), "obj_open", "err %ld\n", PTR_ERR(obj)))
+				return exit_code;
+
+			err = bpf_object__load(obj);
+			if (CHECK_NEWNS(err, "obj_load", "err %d errno %d\n", err, errno))
+				goto cleanup;
+
+			bss_map = bpf_object__find_map_by_name(obj, "test_ns_.bss");
+			if (CHECK_NEWNS(!bss_map, "find_bss_map", "failed\n"))
+				goto cleanup;
+
+			prog = bpf_object__find_program_by_title(obj, probe_name);
+			if (CHECK_NEWNS(!prog, "find_prog", "prog '%s' not found\n",
+						probe_name))
+				goto cleanup;
+
+			memset(&bss, 0, sizeof(bss));
+			pid_t tid = syscall(SYS_gettid);
+			pid_t pid = getpid();
+
+			id = (__u64) tid << 32 | pid;
+			bss.user_pid_tgid = id;
+
+			if (CHECK_NEWNS(stat("/proc/self/ns/pid", &st),
+				"stat new ns", "Failed to stat /proc/self/ns/pid errno=%d\n", errno))
+				goto cleanup;
+
+			bss.dev = st.st_dev;
+			bss.ino = st.st_ino;
+
+			err = bpf_map_update_elem(bpf_map__fd(bss_map), &key, &bss, 0);
+			if (CHECK_NEWNS(err, "setting_bss", "failed to set bss : %d\n", err))
+				goto cleanup;
+
+			link = bpf_program__attach_raw_tracepoint(prog, "sys_enter");
+			if (CHECK_NEWNS(IS_ERR(link), "attach_raw_tp", "err %ld\n",
+						PTR_ERR(link))) {
+				link = NULL;
+				goto cleanup;
+			}
+
+			/* trigger some syscalls */
+			usleep(1);
+
+			err = bpf_map_lookup_elem(bpf_map__fd(bss_map), &key, &bss);
+			if (CHECK_NEWNS(err, "set_bss", "failed to get bss : %d\n", err))
+				goto cleanup;
+
+			if (CHECK_NEWNS(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;
+
+			exit_code = 0;
+			printf("%s:PASS\n", argv[0]);
+cleanup:
+			if (!link) {
+				bpf_link__destroy(link);
+				link = NULL;
+			}
+			bpf_object__close(obj);
+		}
+	}
+}