diff mbox series

[v12,bpf-next,13/14] selftests/bpf: Add test for d_path helper

Message ID 20200825192124.710397-14-jolsa@kernel.org
State Accepted
Delegated to: BPF Maintainers
Headers show
Series bpf: Add d_path helper | expand

Commit Message

Jiri Olsa Aug. 25, 2020, 7:21 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.

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@gmail.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../testing/selftests/bpf/prog_tests/d_path.c | 147 ++++++++++++++++++
 .../testing/selftests/bpf/progs/test_d_path.c |  58 +++++++
 2 files changed, 205 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

Alexei Starovoitov Aug. 25, 2020, 11:06 p.m. UTC | #1 
On Tue, Aug 25, 2020 at 12:22 PM Jiri Olsa <jolsa@kernel.org> wrote:
> +
> +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(pipe(pipefd) < 0, "trigger", "pipe failed\n"))
> +               return ret;
> +       /* unmountable pseudo-filesystems */
> +       sockfd = socket(AF_INET, SOCK_STREAM, 0);
> +       if (CHECK(sockfd < 0, "trigger", "scoket failed\n"))
> +               goto out_close;
> +       /* mountable pseudo-filesystems */
> +       procfd = open("/proc/self/comm", O_RDONLY);
> +       if (CHECK(procfd < 0, "trigger", "open /proc/self/comm failed\n"))
> +               goto out_close;
> +       devfd = open("/dev/urandom", O_RDONLY);
> +       if (CHECK(devfd < 0, "trigger", "open /dev/urandom failed\n"))
> +               goto out_close;
> +       localfd = open("/tmp/d_path_loadgen.txt", O_CREAT | O_RDONLY);

The work-in-progress CI caught a problem here:

In file included from /usr/include/fcntl.h:290:0,
4814                 from ./test_progs.h:29,
4815                 from
/home/travis/build/tsipa/bpf-next/tools/testing/selftests/bpf/prog_tests/d_path.c:3:
4816In function ‘open’,
4817    inlined from ‘trigger_fstat_events’ at
/home/travis/build/tsipa/bpf-next/tools/testing/selftests/bpf/prog_tests/d_path.c:50:10,
4818    inlined from ‘test_d_path’ at
/home/travis/build/tsipa/bpf-next/tools/testing/selftests/bpf/prog_tests/d_path.c:119:6:
4819/usr/include/x86_64-linux-gnu/bits/fcntl2.h:50:4: error: call to
‘__open_missing_mode’ declared with attribute error: open with O_CREAT
or O_TMPFILE in second argument needs 3 arguments
4820    __open_missing_mode ();
4821    ^~~~~~~~~~~~~~~~~~~~~~

I don't see this bug in my setup, since I'm using an older glibc that
doesn't have this check,
so I've pushed it anyway since it was taking a bit long to land and folks were
eagerly waiting for the allowlist and d_path features.
But some other folks may complain about build breakage really soon.
So please follow up asap.
Jiri Olsa Aug. 26, 2020, 9:30 a.m. UTC | #2 
On Tue, Aug 25, 2020 at 04:06:14PM -0700, Alexei Starovoitov wrote:
> On Tue, Aug 25, 2020 at 12:22 PM Jiri Olsa <jolsa@kernel.org> wrote:
> > +
> > +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(pipe(pipefd) < 0, "trigger", "pipe failed\n"))
> > +               return ret;
> > +       /* unmountable pseudo-filesystems */
> > +       sockfd = socket(AF_INET, SOCK_STREAM, 0);
> > +       if (CHECK(sockfd < 0, "trigger", "scoket failed\n"))
> > +               goto out_close;
> > +       /* mountable pseudo-filesystems */
> > +       procfd = open("/proc/self/comm", O_RDONLY);
> > +       if (CHECK(procfd < 0, "trigger", "open /proc/self/comm failed\n"))
> > +               goto out_close;
> > +       devfd = open("/dev/urandom", O_RDONLY);
> > +       if (CHECK(devfd < 0, "trigger", "open /dev/urandom failed\n"))
> > +               goto out_close;
> > +       localfd = open("/tmp/d_path_loadgen.txt", O_CREAT | O_RDONLY);
> 
> The work-in-progress CI caught a problem here:
> 
> In file included from /usr/include/fcntl.h:290:0,
> 4814                 from ./test_progs.h:29,
> 4815                 from
> /home/travis/build/tsipa/bpf-next/tools/testing/selftests/bpf/prog_tests/d_path.c:3:
> 4816In function ‘open’,
> 4817    inlined from ‘trigger_fstat_events’ at
> /home/travis/build/tsipa/bpf-next/tools/testing/selftests/bpf/prog_tests/d_path.c:50:10,
> 4818    inlined from ‘test_d_path’ at
> /home/travis/build/tsipa/bpf-next/tools/testing/selftests/bpf/prog_tests/d_path.c:119:6:
> 4819/usr/include/x86_64-linux-gnu/bits/fcntl2.h:50:4: error: call to
> ‘__open_missing_mode’ declared with attribute error: open with O_CREAT
> or O_TMPFILE in second argument needs 3 arguments
> 4820    __open_missing_mode ();
> 4821    ^~~~~~~~~~~~~~~~~~~~~~

ok, looks like it's missing the permission bits

> 
> I don't see this bug in my setup, since I'm using an older glibc that
> doesn't have this check,
> so I've pushed it anyway since it was taking a bit long to land and folks were
> eagerly waiting for the allowlist and d_path features.
> But some other folks may complain about build breakage really soon.
> So please follow up asap.

time to upadte my systems, I'm missing new warnings ;-)

I'll send the fix

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..058765da17e6
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/d_path.c
@@ -0,0 +1,147 @@ 
+// 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
+
+#include "test_d_path.skel.h"
+
+static int duration;
+
+static struct {
+	__u32 cnt;
+	char paths[MAX_FILES][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(pipe(pipefd) < 0, "trigger", "pipe failed\n"))
+		return ret;
+	/* unmountable pseudo-filesystems */
+	sockfd = socket(AF_INET, SOCK_STREAM, 0);
+	if (CHECK(sockfd < 0, "trigger", "scoket failed\n"))
+		goto out_close;
+	/* mountable pseudo-filesystems */
+	procfd = open("/proc/self/comm", O_RDONLY);
+	if (CHECK(procfd < 0, "trigger", "open /proc/self/comm failed\n"))
+		goto out_close;
+	devfd = open("/dev/urandom", O_RDONLY);
+	if (CHECK(devfd < 0, "trigger", "open /dev/urandom failed\n"))
+		goto out_close;
+	localfd = open("/tmp/d_path_loadgen.txt", O_CREAT | O_RDONLY);
+	if (CHECK(localfd < 0, "trigger", "open /tmp/d_path_loadgen.txt failed\n"))
+		goto out_close;
+	/* bpf_d_path will return path with (deleted) */
+	remove("/tmp/d_path_loadgen.txt");
+	indicatorfd = open("/tmp/", O_PATH);
+	if (CHECK(indicatorfd < 0, "trigger", "open /tmp/ failed\n"))
+		goto out_close;
+
+	ret = set_pathname(pipefd[0], pid);
+	if (CHECK(ret < 0, "trigger", "set_pathname failed for pipe[0]\n"))
+		goto out_close;
+	ret = set_pathname(pipefd[1], pid);
+	if (CHECK(ret < 0, "trigger", "set_pathname failed for pipe[1]\n"))
+		goto out_close;
+	ret = set_pathname(sockfd, pid);
+	if (CHECK(ret < 0, "trigger", "set_pathname failed for socket\n"))
+		goto out_close;
+	ret = set_pathname(procfd, pid);
+	if (CHECK(ret < 0, "trigger", "set_pathname failed for proc\n"))
+		goto out_close;
+	ret = set_pathname(devfd, pid);
+	if (CHECK(ret < 0, "trigger", "set_pathname failed for dev\n"))
+		goto out_close;
+	ret = set_pathname(localfd, pid);
+	if (CHECK(ret < 0, "trigger", "set_pathname failed for file\n"))
+		goto out_close;
+	ret = set_pathname(indicatorfd, pid);
+	if (CHECK(ret < 0, "trigger", "set_pathname failed for dir\n"))
+		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;
+	int err;
+
+	skel = test_d_path__open_and_load();
+	if (CHECK(!skel, "setup", "d_path skeleton failed\n"))
+		goto cleanup;
+
+	err = test_d_path__attach(skel);
+	if (CHECK(err, "setup", "attach failed: %d\n", err))
+		goto cleanup;
+
+	bss = skel->bss;
+	bss->my_pid = getpid();
+
+	err = trigger_fstat_events(bss->my_pid);
+	if (err < 0)
+		goto cleanup;
+
+	for (int i = 0; i < MAX_FILES; i++) {
+		CHECK(strncmp(src.paths[i], bss->paths_stat[i], MAX_PATH_LEN),
+		      "check",
+		      "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),
+		      "check",
+		      "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,
+		      "check",
+		      "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,
+		      "check",
+		      "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..61f007855649
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_d_path.c
@@ -0,0 +1,58 @@ 
+// 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_FILES		7
+
+pid_t my_pid = 0;
+__u32 cnt_stat = 0;
+__u32 cnt_close = 0;
+char paths_stat[MAX_FILES][MAX_PATH_LEN] = {};
+char paths_close[MAX_FILES][MAX_PATH_LEN] = {};
+int rets_stat[MAX_FILES] = {};
+int rets_close[MAX_FILES] = {};
+
+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;
+	__u32 cnt = cnt_stat;
+	int ret;
+
+	if (pid != my_pid)
+		return 0;
+
+	if (cnt >= MAX_FILES)
+		return 0;
+	ret = bpf_d_path(path, paths_stat[cnt], MAX_PATH_LEN);
+
+	rets_stat[cnt] = 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;
+	__u32 cnt = cnt_close;
+	int ret;
+
+	if (pid != my_pid)
+		return 0;
+
+	if (cnt >= MAX_FILES)
+		return 0;
+	ret = bpf_d_path(&file->f_path,
+			 paths_close[cnt], MAX_PATH_LEN);
+
+	rets_close[cnt] = ret;
+	cnt_close++;
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";