[PATCH v2 bpf-next 03/18] selftests/bpf: add BPF_TOKEN_CREATE test

Andrii Nakryiko
2023-06-07T23:54:13Z

Add a subtest validating BPF_TOKEN_CREATE command, pinning/getting BPF
token in/from BPF FS, and creating derived BPF tokens using token_fd
parameter.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
.../testing/selftests/bpf/prog_tests/token.c | 93 +++++++++++++++++++
1 file changed, 93 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/token.c

diff --git a/tools/testing/selftests/bpf/prog_tests/token.c b/tools/testing/selftests/bpf/prog_tests/token.c
new file mode 100644
index 000000000000..cba84c480ac5
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/token.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+#include "linux/bpf.h"
+#include <test_progs.h>
+#include <bpf/btf.h>
+#include "cap_helpers.h"
+
+static int drop_priv_caps(__u64 *old_caps)
+{
+ return cap_disable_effective((1ULL << CAP_BPF) |
+ (1ULL << CAP_PERFMON) |
+ (1ULL << CAP_NET_ADMIN) |
+ (1ULL << CAP_SYS_ADMIN), old_caps);
+}
+
+static int restore_priv_caps(__u64 old_caps)
+{
+ return cap_enable_effective(old_caps, NULL);
+}
+
+#define TOKEN_PATH "/sys/fs/bpf/test_token"
+
+static void subtest_token_create(void)
+{
+ LIBBPF_OPTS(bpf_token_create_opts, opts);
+ int token_fd = 0, limited_token_fd = 0, tmp_fd = 0, err;
+ __u64 old_caps = 0;
+
+ /* check that any current and future cmd can be specified */
+ opts.allowed_cmds = ~0ULL;
+ token_fd = bpf_token_create(&opts);
+ if (!ASSERT_GT(token_fd, 0, "token_create_future_proof"))
+ return;
+ close(token_fd);
+
+ /* create BPF token which allows creating derived BPF tokens */
+ opts.allowed_cmds = 1ULL << BPF_TOKEN_CREATE;
+ token_fd = bpf_token_create(&opts);
+ if (!ASSERT_GT(token_fd, 0, "token_create"))
+ return;
+
+ /* validate pinning and getting works as expected */
+ err = bpf_obj_pin(token_fd, TOKEN_PATH);
+ if (!ASSERT_OK(err, "token_pin"))
+ goto cleanup;
+
+ tmp_fd = bpf_obj_get(TOKEN_PATH);
+ ASSERT_GT(tmp_fd, 0, "token_get");
+ close(tmp_fd);
+ tmp_fd = 0;
+ unlink(TOKEN_PATH);
+
+ /* drop privileges to test token_fd passing */
+ if (!ASSERT_OK(drop_priv_caps(&old_caps), "drop_caps"))
+ goto cleanup;
+
+ /* unprivileged BPF_TOKEN_CREATE should fail */
+ tmp_fd = bpf_token_create(NULL);
+ if (!ASSERT_LT(tmp_fd, 0, "token_create_unpriv_fail"))
+ goto cleanup;
+
+ /* unprivileged BPF_TOKEN_CREATE with associated BPF token succeeds */
+ opts.flags = 0;
+ opts.allowed_cmds = 0; /* ask for BPF token which doesn't allow new tokens */
+ opts.token_fd = token_fd;
+ limited_token_fd = bpf_token_create(&opts);
+ if (!ASSERT_GT(limited_token_fd, 0, "token_create_limited"))
+ goto cleanup;
+
+ /* creating yet another token using "limited" BPF token should fail */
+ opts.flags = 0;
+ opts.allowed_cmds = 0;
+ opts.token_fd = limited_token_fd;
+ tmp_fd = bpf_token_create(&opts);
+ if (!ASSERT_LT(tmp_fd, 0, "token_create_from_lim_fail"))
+ goto cleanup;
+
+cleanup:
+ if (tmp_fd)
+ close(tmp_fd);
+ if (token_fd)
+ close(token_fd);
+ if (limited_token_fd)
+ close(limited_token_fd);
+ if (old_caps)
+ ASSERT_OK(restore_priv_caps(old_caps), "restore_caps");
+}
+
+void test_token(void)
+{
+ if (test__start_subtest("token_create"))
+ subtest_token_create();
+}
--
2.34.1