Adding test for d_path helper which is pretty much
copied from Wenbo Zhang's test for bpf_get_fd_path,
which never made it in.
The test is doing fstat/close on several fd types,
and verifies we got the d_path helper working on
kernel probes for vfs_getattr/filp_close functions.
Original-patch-by: Wenbo Zhang <ethercflow@xxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
.../testing/selftests/bpf/prog_tests/d_path.c | 162 ++++++++++++++++++
.../testing/selftests/bpf/progs/test_d_path.c | 64 +++++++
2 files changed, 226 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/d_path.c
create mode 100644 tools/testing/selftests/bpf/progs/test_d_path.c
diff --git a/tools/testing/selftests/bpf/prog_tests/d_path.c b/tools/testing/selftests/bpf/prog_tests/d_path.c
new file mode 100644
index 000000000000..3b8f87fb17d7
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/d_path.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <test_progs.h>
+#include <sys/stat.h>
+#include <linux/sched.h>
+#include <sys/syscall.h>
+
+#define MAX_PATH_LEN 128
+#define MAX_FILES 7
+#define MAX_EVENT_NUM 16
+
+#include "test_d_path.skel.h"
+
+static struct {
+ __u32 cnt;
+ char paths[MAX_EVENT_NUM][MAX_PATH_LEN];
+} src;
+
+static int set_pathname(int fd, pid_t pid)
+{
+ char buf[MAX_PATH_LEN];
+
+ snprintf(buf, MAX_PATH_LEN, "/proc/%d/fd/%d", pid, fd);
+ return readlink(buf, src.paths[src.cnt++], MAX_PATH_LEN);
+}
+
+static int trigger_fstat_events(pid_t pid)
+{
+ int sockfd = -1, procfd = -1, devfd = -1;
+ int localfd = -1, indicatorfd = -1;
+ int pipefd[2] = { -1, -1 };
+ struct stat fileStat;
+ int ret = -1;
+
+ /* unmountable pseudo-filesystems */
+ if (CHECK_FAIL(pipe(pipefd) < 0))
+ return ret;
+ /* unmountable pseudo-filesystems */
+ sockfd = socket(AF_INET, SOCK_STREAM, 0);
+ if (CHECK_FAIL(sockfd < 0))
+ goto out_close;
+ /* mountable pseudo-filesystems */
+ procfd = open("/proc/self/comm", O_RDONLY);
+ if (CHECK_FAIL(procfd < 0))
+ goto out_close;
+ devfd = open("/dev/urandom", O_RDONLY);
+ if (CHECK_FAIL(devfd < 0))
+ goto out_close;
+ localfd = open("/tmp/d_path_loadgen.txt", O_CREAT | O_RDONLY);
+ if (CHECK_FAIL(localfd < 0))
+ goto out_close;
+ /* bpf_d_path will return path with (deleted) */
+ remove("/tmp/d_path_loadgen.txt");
+ indicatorfd = open("/tmp/", O_PATH);
+ if (CHECK_FAIL(indicatorfd < 0))
+ goto out_close;
+
+ ret = set_pathname(pipefd[0], pid);
+ if (CHECK_FAIL(ret < 0))
+ goto out_close;
+ ret = set_pathname(pipefd[1], pid);
+ if (CHECK_FAIL(ret < 0))
+ goto out_close;
+ ret = set_pathname(sockfd, pid);
+ if (CHECK_FAIL(ret < 0))
+ goto out_close;
+ ret = set_pathname(procfd, pid);
+ if (CHECK_FAIL(ret < 0))
+ goto out_close;
+ ret = set_pathname(devfd, pid);
+ if (CHECK_FAIL(ret < 0))
+ goto out_close;
+ ret = set_pathname(localfd, pid);
+ if (CHECK_FAIL(ret < 0))
+ goto out_close;
+ ret = set_pathname(indicatorfd, pid);
+ if (CHECK_FAIL(ret < 0))
+ goto out_close;
+
+ /* triggers vfs_getattr */
+ fstat(pipefd[0], &fileStat);
+ fstat(pipefd[1], &fileStat);
+ fstat(sockfd, &fileStat);
+ fstat(procfd, &fileStat);
+ fstat(devfd, &fileStat);
+ fstat(localfd, &fileStat);
+ fstat(indicatorfd, &fileStat);
+
+out_close:
+ /* triggers filp_close */
+ close(pipefd[0]);
+ close(pipefd[1]);
+ close(sockfd);
+ close(procfd);
+ close(devfd);
+ close(localfd);
+ close(indicatorfd);
+ return ret;
+}
+
+void test_d_path(void)
+{
+ struct test_d_path__bss *bss;
+ struct test_d_path *skel;
+ __u32 duration = 0;
+ int err;
+
+ skel = test_d_path__open_and_load();
+ if (CHECK(!skel, "test_d_path_load", "d_path skeleton failed\n"))
+ goto cleanup;
+
+ err = test_d_path__attach(skel);
+ if (CHECK(err, "modify_return", "attach failed: %d\n", err))
+ goto cleanup;
+
+ bss = skel->bss;
+ bss->my_pid = getpid();
+
+ err = trigger_fstat_events(bss->my_pid);
+ if (CHECK_FAIL(err < 0))
+ goto cleanup;
+
+ for (int i = 0; i < MAX_FILES; i++) {
+ if (i < 3) {
+ CHECK((bss->paths_stat[i][0] == 0), "d_path",
+ "failed to filter fs [%d]: %s vs %s\n",
+ i, src.paths[i], bss->paths_stat[i]);
+ CHECK((bss->paths_close[i][0] == 0), "d_path",
+ "failed to filter fs [%d]: %s vs %s\n",
+ i, src.paths[i], bss->paths_close[i]);
+ CHECK((bss->rets_stat[i] < 0), "d_path",
+ "failed to filter fs [%d]: %s vs %s\n",
+ i, src.paths[i], bss->paths_close[i]);
+ CHECK((bss->rets_close[i] < 0), "d_path",
+ "failed to filter fs [%d]: %s vs %s\n",
+ i, src.paths[i], bss->paths_close[i]);
+ } else {
+ CHECK(strncmp(src.paths[i], bss->paths_stat[i], MAX_PATH_LEN),
+ "d_path",
+ "failed to get stat path[%d]: %s vs %s\n",
+ i, src.paths[i], bss->paths_stat[i]);
+ CHECK(strncmp(src.paths[i], bss->paths_close[i], MAX_PATH_LEN),
+ "d_path",
+ "failed to get close path[%d]: %s vs %s\n",
+ i, src.paths[i], bss->paths_close[i]);
+ /* The d_path helper returns size plus NUL char, hence + 1 */
+ CHECK(bss->rets_stat[i] != strlen(bss->paths_stat[i]) + 1,
+ "d_path",
+ "failed to match stat return [%d]: %d vs %zd [%s]\n",
+ i, bss->rets_stat[i], strlen(bss->paths_stat[i]) + 1,
+ bss->paths_stat[i]);
+ CHECK(bss->rets_close[i] != strlen(bss->paths_stat[i]) + 1,
+ "d_path",
+ "failed to match stat return [%d]: %d vs %zd [%s]\n",
+ i, bss->rets_close[i], strlen(bss->paths_close[i]) + 1,
+ bss->paths_stat[i]);
+ }
+ }
+
+cleanup:
+ test_d_path__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_d_path.c b/tools/testing/selftests/bpf/progs/test_d_path.c
new file mode 100644
index 000000000000..e02dce614256
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_d_path.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#define MAX_PATH_LEN 128
+#define MAX_EVENT_NUM 16
+
+pid_t my_pid;
+__u32 cnt_stat;
+__u32 cnt_close;
+char paths_stat[MAX_EVENT_NUM][MAX_PATH_LEN];
+char paths_close[MAX_EVENT_NUM][MAX_PATH_LEN];
+int rets_stat[MAX_EVENT_NUM];
+int rets_close[MAX_EVENT_NUM];
+
+SEC("fentry/vfs_getattr")
+int BPF_PROG(prog_stat, struct path *path, struct kstat *stat,
+ __u32 request_mask, unsigned int query_flags)
+{
+ pid_t pid = bpf_get_current_pid_tgid() >> 32;
+ int ret;
+
+ if (pid != my_pid)
+ return 0;
+
+ if (cnt_stat >= MAX_EVENT_NUM)
+ return 0;
+ ret = bpf_d_path(path, paths_stat[cnt_stat], MAX_PATH_LEN);
+
+ /* We need to recheck cnt_stat for verifier. */
+ if (cnt_stat >= MAX_EVENT_NUM)
+ return 0;
+ rets_stat[cnt_stat] = ret;
+
+ cnt_stat++;
+ return 0;
+}
+
+SEC("fentry/filp_close")
+int BPF_PROG(prog_close, struct file *file, void *id)
+{
+ pid_t pid = bpf_get_current_pid_tgid() >> 32;
+ int ret;
+
+ if (pid != my_pid)
+ return 0;
+
+ if (cnt_close >= MAX_EVENT_NUM)
+ return 0;
+ ret = bpf_d_path(&file->f_path,
+ paths_close[cnt_close], MAX_PATH_LEN);
+
+ /* We need to recheck cnt_stat for verifier. */
+ if (cnt_close >= MAX_EVENT_NUM)
+ return 0;
+ rets_close[cnt_close] = ret;
+
+ cnt_close++;
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.25.4
