diff mbox series

[v4,bpf-next,13/14] selftests/bpf: Add test for d_path helper

Message ID 20200625221304.2817194-14-jolsa@kernel.org
State Changes Requested
Delegated to: BPF Maintainers
Headers show
Series bpf: Add d_path helper | expand

Commit Message

Jiri Olsa June 25, 2020, 10:13 p.m. UTC
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.

I've failed so far to compile the test with <linux/fs.h>
kernel header, so for now adding 'struct file' with f_path
member that has same offset as kernel's file object.

Original-patch-by: Wenbo Zhang <ethercflow@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../testing/selftests/bpf/prog_tests/d_path.c | 145 ++++++++++++++++++
 .../testing/selftests/bpf/progs/test_d_path.c |  50 ++++++
 2 files changed, 195 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

Comments

Andrii Nakryiko June 26, 2020, 9:55 p.m. UTC | #1
On Thu, Jun 25, 2020 at 4:49 PM Jiri Olsa <jolsa@kernel.org> wrote:
>
> 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.
>
> I've failed so far to compile the test with <linux/fs.h>
> kernel header, so for now adding 'struct file' with f_path
> member that has same offset as kernel's file object.
>
> Original-patch-by: Wenbo Zhang <ethercflow@gmail.com>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  .../testing/selftests/bpf/prog_tests/d_path.c | 145 ++++++++++++++++++
>  .../testing/selftests/bpf/progs/test_d_path.c |  50 ++++++
>  2 files changed, 195 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/progs/test_d_path.c b/tools/testing/selftests/bpf/progs/test_d_path.c
> new file mode 100644
> index 000000000000..6096aef2bafc
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_d_path.c
> @@ -0,0 +1,50 @@
> +// 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];
> +
> +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;
> +
> +       if (pid != my_pid)
> +               return 0;
> +
> +       if (cnt_stat >= MAX_EVENT_NUM)
> +               return 0;
> +
> +       bpf_d_path(path, paths_stat[cnt_stat], MAX_PATH_LEN);
> +       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;
> +
> +       if (pid != my_pid)
> +               return 0;
> +
> +       if (cnt_close >= MAX_EVENT_NUM)
> +               return 0;
> +
> +       bpf_d_path((struct path *) &file->f_path,
> +                  paths_close[cnt_close], MAX_PATH_LEN);

Can you please capture the return result of bpf_d_path() (here and
above) and validate that it's correct? That will help avoid future
breakages if anyone changes this.

> +       cnt_close++;
> +       return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.25.4
>
Jiri Olsa June 28, 2020, 7:55 p.m. UTC | #2
On Fri, Jun 26, 2020 at 02:55:34PM -0700, Andrii Nakryiko wrote:

SNIP

> > +       if (cnt_stat >= MAX_EVENT_NUM)
> > +               return 0;
> > +
> > +       bpf_d_path(path, paths_stat[cnt_stat], MAX_PATH_LEN);
> > +       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;
> > +
> > +       if (pid != my_pid)
> > +               return 0;
> > +
> > +       if (cnt_close >= MAX_EVENT_NUM)
> > +               return 0;
> > +
> > +       bpf_d_path((struct path *) &file->f_path,
> > +                  paths_close[cnt_close], MAX_PATH_LEN);
> 
> Can you please capture the return result of bpf_d_path() (here and
> above) and validate that it's correct? That will help avoid future
> breakages if anyone changes this.

right, good idea, will add

thanks,
jirka
diff mbox series

Patch

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..c0ea45d43634
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/d_path.c
@@ -0,0 +1,145 @@ 
+// 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]);
+		} 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]);
+		}
+	}
+
+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..6096aef2bafc
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_d_path.c
@@ -0,0 +1,50 @@ 
+// 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];
+
+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;
+
+	if (pid != my_pid)
+		return 0;
+
+	if (cnt_stat >= MAX_EVENT_NUM)
+		return 0;
+
+	bpf_d_path(path, paths_stat[cnt_stat], MAX_PATH_LEN);
+	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;
+
+	if (pid != my_pid)
+		return 0;
+
+	if (cnt_close >= MAX_EVENT_NUM)
+		return 0;
+
+	bpf_d_path((struct path *) &file->f_path,
+		   paths_close[cnt_close], MAX_PATH_LEN);
+	cnt_close++;
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";