[PATCH v11 bpf-next 2/7] selftests/bpf: Extend test fs_kfuncs to cover security.bpf. xattr names

Song Liu
2025-01-29T21:00:21Z

Extend test_progs fs_kfuncs to cover different xattr names. Specifically:
xattr name "user.kfuncs" and "security.bpf.xxx" can be read from BPF
program with kfuncs bpf_get_[file|dentry]_xattr(); while "security.bpf"
and "security.selinux" cannot be read.

Signed-off-by: Song Liu <song@kernel.org>
---
.../selftests/bpf/prog_tests/fs_kfuncs.c | 37 ++++++++++++++-----
.../selftests/bpf/progs/test_get_xattr.c | 28 ++++++++++++--
2 files changed, 51 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c b/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c
index 5a0b51157451..419f45b56472 100644
--- a/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c
+++ b/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c
@@ -12,7 +12,7 @@

static const char testfile[] = "/tmp/test_progs_fs_kfuncs";

-static void test_xattr(void)
+static void test_get_xattr(const char *name, const char *value, bool allow_access)
{
struct test_get_xattr *skel = NULL;
int fd = -1, err;
@@ -25,7 +25,7 @@ static void test_xattr(void)
close(fd);
fd = -1;

- err = setxattr(testfile, "user.kfuncs", "hello", sizeof("hello"), 0);
+ err = setxattr(testfile, name, value, strlen(value) + 1, 0);
if (err && errno == EOPNOTSUPP) {
printf("%s:SKIP:local fs doesn't support xattr (%d)\n"
"To run this test, make sure /tmp filesystem supports xattr.\n",
@@ -48,16 +48,23 @@ static void test_xattr(void)
goto out;

fd = open(testfile, O_RDONLY, 0644);
+
if (!ASSERT_GE(fd, 0, "open_file"))
goto out;

- ASSERT_EQ(skel->bss->found_xattr_from_file, 1, "found_xattr_from_file");
-
/* Trigger security_inode_getxattr */
- err = getxattr(testfile, "user.kfuncs", v, sizeof(v));
- ASSERT_EQ(err, -1, "getxattr_return");
- ASSERT_EQ(errno, EINVAL, "getxattr_errno");
- ASSERT_EQ(skel->bss->found_xattr_from_dentry, 1, "found_xattr_from_dentry");
+ err = getxattr(testfile, name, v, sizeof(v));
+
+ if (allow_access) {
+ ASSERT_EQ(err, -1, "getxattr_return");
+ ASSERT_EQ(errno, EINVAL, "getxattr_errno");
+ ASSERT_EQ(skel->bss->found_xattr_from_file, 1, "found_xattr_from_file");
+ ASSERT_EQ(skel->bss->found_xattr_from_dentry, 1, "found_xattr_from_dentry");
+ } else {
+ ASSERT_EQ(err, strlen(value) + 1, "getxattr_return");
+ ASSERT_EQ(skel->bss->found_xattr_from_file, 0, "found_xattr_from_file");
+ ASSERT_EQ(skel->bss->found_xattr_from_dentry, 0, "found_xattr_from_dentry");
+ }

out:
close(fd);
@@ -141,8 +148,18 @@ static void test_fsverity(void)

void test_fs_kfuncs(void)
{
- if (test__start_subtest("xattr"))
- test_xattr();
+ /* Matches xattr_names in progs/test_get_xattr.c */
+ if (test__start_subtest("user_xattr"))
+ test_get_xattr("user.kfuncs", "hello", true);
+
+ if (test__start_subtest("security_bpf_xattr"))
+ test_get_xattr("security.bpf.xxx", "hello", true);
+
+ if (test__start_subtest("security_bpf_xattr_error"))
+ test_get_xattr("security.bpf", "hello", false);
+
+ if (test__start_subtest("security_selinux_xattr_error"))
+ test_get_xattr("security.selinux", "hello", false);

if (test__start_subtest("fsverity"))
test_fsverity();
diff --git a/tools/testing/selftests/bpf/progs/test_get_xattr.c b/tools/testing/selftests/bpf/progs/test_get_xattr.c
index 66e737720f7c..54305f4c9f2d 100644
--- a/tools/testing/selftests/bpf/progs/test_get_xattr.c
+++ b/tools/testing/selftests/bpf/progs/test_get_xattr.c
@@ -6,6 +6,7 @@
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "bpf_kfuncs.h"
+#include "bpf_misc.h"

char _license[] SEC("license") = "GPL";

@@ -17,12 +18,23 @@ static const char expected_value[] = "hello";
char value1[32];
char value2[32];

+/* Matches caller of test_get_xattr() in prog_tests/fs_kfuncs.c */
+static const char xattr_names[][64] = {
+ /* The following work. */
+ "user.kfuncs",
+ "security.bpf.xxx",
+
+ /* The following do not work. */
+ "security.bpf",
+ "security.selinux"
+};
+
SEC("lsm.s/file_open")
int BPF_PROG(test_file_open, struct file *f)
{
struct bpf_dynptr value_ptr;
__u32 pid;
- int ret;
+ int ret, i;

pid = bpf_get_current_pid_tgid() >> 32;
if (pid != monitored_pid)
@@ -30,7 +42,11 @@ int BPF_PROG(test_file_open, struct file *f)

bpf_dynptr_from_mem(value1, sizeof(value1), 0, &value_ptr);

- ret = bpf_get_file_xattr(f, "user.kfuncs", &value_ptr);
+ for (i = 0; i < ARRAY_SIZE(xattr_names); i++) {
+ ret = bpf_get_file_xattr(f, xattr_names[i], &value_ptr);
+ if (ret == sizeof(expected_value))
+ break;
+ }
if (ret != sizeof(expected_value))
return 0;
if (bpf_strncmp(value1, ret, expected_value))
@@ -44,7 +60,7 @@ int BPF_PROG(test_inode_getxattr, struct dentry *dentry, char *name)
{
struct bpf_dynptr value_ptr;
__u32 pid;
- int ret;
+ int ret, i;

pid = bpf_get_current_pid_tgid() >> 32;
if (pid != monitored_pid)
@@ -52,7 +68,11 @@ int BPF_PROG(test_inode_getxattr, struct dentry *dentry, char *name)

bpf_dynptr_from_mem(value2, sizeof(value2), 0, &value_ptr);

- ret = bpf_get_dentry_xattr(dentry, "user.kfuncs", &value_ptr);
+ for (i = 0; i < ARRAY_SIZE(xattr_names); i++) {
+ ret = bpf_get_dentry_xattr(dentry, xattr_names[i], &value_ptr);
+ if (ret == sizeof(expected_value))
+ break;
+ }
if (ret != sizeof(expected_value))
return 0;
if (bpf_strncmp(value2, ret, expected_value))
--
2.43.5