[PATCH bpf-next 26/29] selftests/bpf: add BPF object loading tests with explicit token passing

Andrii Nakryiko
2024-01-03T22:25:07Z

Add a few tests that attempt to load BPF object containing privileged
map, program, and the one requiring mandatory BTF uploading into the
kernel (to validate token FD propagation to BPF_BTF_LOAD command).

Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
.../testing/selftests/bpf/prog_tests/token.c | 140 ++++++++++++++++++
tools/testing/selftests/bpf/progs/priv_map.c | 13 ++
tools/testing/selftests/bpf/progs/priv_prog.c | 13 ++
3 files changed, 166 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/priv_map.c
create mode 100644 tools/testing/selftests/bpf/progs/priv_prog.c

diff --git a/tools/testing/selftests/bpf/prog_tests/token.c b/tools/testing/selftests/bpf/prog_tests/token.c
index 185ed2f79315..1594d9b94b13 100644
--- a/tools/testing/selftests/bpf/prog_tests/token.c
+++ b/tools/testing/selftests/bpf/prog_tests/token.c
@@ -14,6 +14,9 @@
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/un.h>
+#include "priv_map.skel.h"
+#include "priv_prog.skel.h"
+#include "dummy_st_ops_success.skel.h"

static inline int sys_mount(const char *dev_name, const char *dir_name,
const char *type, unsigned long flags,
@@ -666,6 +669,104 @@ static int userns_prog_load(int mnt_fd)
return err;
}

+static int userns_obj_priv_map(int mnt_fd)
+{
+ LIBBPF_OPTS(bpf_object_open_opts, opts);
+ char buf[256];
+ struct priv_map *skel;
+ int err;
+
+ skel = priv_map__open_and_load();
+ if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) {
+ priv_map__destroy(skel);
+ return -EINVAL;
+ }
+
+ /* use bpf_token_path to provide BPF FS path */
+ snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd);
+ opts.bpf_token_path = buf;
+ skel = priv_map__open_opts(&opts);
+ if (!ASSERT_OK_PTR(skel, "obj_token_path_open"))
+ return -EINVAL;
+
+ err = priv_map__load(skel);
+ priv_map__destroy(skel);
+ if (!ASSERT_OK(err, "obj_token_path_load"))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int userns_obj_priv_prog(int mnt_fd)
+{
+ LIBBPF_OPTS(bpf_object_open_opts, opts);
+ char buf[256];
+ struct priv_prog *skel;
+ int err;
+
+ skel = priv_prog__open_and_load();
+ if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) {
+ priv_prog__destroy(skel);
+ return -EINVAL;
+ }
+
+ /* use bpf_token_path to provide BPF FS path */
+ snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd);
+ opts.bpf_token_path = buf;
+ skel = priv_prog__open_opts(&opts);
+ if (!ASSERT_OK_PTR(skel, "obj_token_path_open"))
+ return -EINVAL;
+
+ err = priv_prog__load(skel);
+ priv_prog__destroy(skel);
+ if (!ASSERT_OK(err, "obj_token_path_load"))
+ return -EINVAL;
+
+ return 0;
+}
+
+/* this test is called with BPF FS that doesn't delegate BPF_BTF_LOAD command,
+ * which should cause struct_ops application to fail, as BTF won't be uploaded
+ * into the kernel, even if STRUCT_OPS programs themselves are allowed
+ */
+static int validate_struct_ops_load(int mnt_fd, bool expect_success)
+{
+ LIBBPF_OPTS(bpf_object_open_opts, opts);
+ char buf[256];
+ struct dummy_st_ops_success *skel;
+ int err;
+
+ snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd);
+ opts.bpf_token_path = buf;
+ skel = dummy_st_ops_success__open_opts(&opts);
+ if (!ASSERT_OK_PTR(skel, "obj_token_path_open"))
+ return -EINVAL;
+
+ err = dummy_st_ops_success__load(skel);
+ dummy_st_ops_success__destroy(skel);
+ if (expect_success) {
+ if (!ASSERT_OK(err, "obj_token_path_load"))
+ return -EINVAL;
+ } else /* expect failure */ {
+ if (!ASSERT_ERR(err, "obj_token_path_load"))
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int userns_obj_priv_btf_fail(int mnt_fd)
+{
+ return validate_struct_ops_load(mnt_fd, false /* should fail */);
+}
+
+static int userns_obj_priv_btf_success(int mnt_fd)
+{
+ return validate_struct_ops_load(mnt_fd, true /* should succeed */);
+}
+
+#define bit(n) (1ULL << (n))
+
void test_token(void)
{
if (test__start_subtest("map_token")) {
@@ -692,4 +793,43 @@ void test_token(void)

subtest_userns(&opts, userns_prog_load);
}
+ if (test__start_subtest("obj_priv_map")) {
+ struct bpffs_opts opts = {
+ .cmds = bit(BPF_MAP_CREATE),
+ .maps = bit(BPF_MAP_TYPE_QUEUE),
+ };
+
+ subtest_userns(&opts, userns_obj_priv_map);
+ }
+ if (test__start_subtest("obj_priv_prog")) {
+ struct bpffs_opts opts = {
+ .cmds = bit(BPF_PROG_LOAD),
+ .progs = bit(BPF_PROG_TYPE_KPROBE),
+ .attachs = ~0ULL,
+ };
+
+ subtest_userns(&opts, userns_obj_priv_prog);
+ }
+ if (test__start_subtest("obj_priv_btf_fail")) {
+ struct bpffs_opts opts = {
+ /* disallow BTF loading */
+ .cmds = bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD),
+ .maps = bit(BPF_MAP_TYPE_STRUCT_OPS),
+ .progs = bit(BPF_PROG_TYPE_STRUCT_OPS),
+ .attachs = ~0ULL,
+ };
+
+ subtest_userns(&opts, userns_obj_priv_btf_fail);
+ }
+ if (test__start_subtest("obj_priv_btf_success")) {
+ struct bpffs_opts opts = {
+ /* allow BTF loading */
+ .cmds = bit(BPF_BTF_LOAD) | bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD),
+ .maps = bit(BPF_MAP_TYPE_STRUCT_OPS),
+ .progs = bit(BPF_PROG_TYPE_STRUCT_OPS),
+ .attachs = ~0ULL,
+ };
+
+ subtest_userns(&opts, userns_obj_priv_btf_success);
+ }
}
diff --git a/tools/testing/selftests/bpf/progs/priv_map.c b/tools/testing/selftests/bpf/progs/priv_map.c
new file mode 100644
index 000000000000..9085be50f03b
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/priv_map.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+ __uint(type, BPF_MAP_TYPE_QUEUE);
+ __uint(max_entries, 1);
+ __type(value, __u32);
+} priv_map SEC(".maps");
diff --git a/tools/testing/selftests/bpf/progs/priv_prog.c b/tools/testing/selftests/bpf/progs/priv_prog.c
new file mode 100644
index 000000000000..3c7b2b618c8a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/priv_prog.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("kprobe")
+int kprobe_prog(void *ctx)
+{
+ return 1;
+}
--
2.34.1