Re: [PATCH v15 12/12] selftests/bpf: Add tests for dynamic pointers parameters in kfuncs

On Wed, 2022-08-31 at 18:54 +0200, Roberto Sassu wrote:

From: Roberto Sassu roberto.sassu@huawei.com

Add tests to ensure that only supported dynamic pointer types are accepted, that the passed argument is actually a dynamic pointer, and that the passed argument is a pointer to the stack.

Sorry, forgot to add this test to the deny list of s390.

I also rebased to the latest commit.

Let me know if I should resend.

Thanks

Roberto

Signed-off-by: Roberto Sassu roberto.sassu@huawei.com

.../bpf/prog_tests/kfunc_dynptr_param.c | 102 ++++++++++++++++++ .../bpf/progs/test_kfunc_dynptr_param.c | 57 ++++++++++ 2 files changed, 159 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c create mode 100644 tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c

diff --git a/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c b/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c new file mode 100644 index 000000000000..732897faf36b --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c @@ -0,0 +1,102 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (c) 2022 Facebook
• • Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
• • Author: Roberto Sassu roberto.sassu@huawei.com
• */

+#include <test_progs.h> +#include "test_kfunc_dynptr_param.skel.h"

+static size_t log_buf_sz = 1048576; /* 1 MB */ +static char obj_log_buf[1048576];

+static struct {

• const char *prog_name;
• const char *expected_err_msg;

+} kfunc_dynptr_tests[] = {

• {"dynptr_type_not_supp",

• "arg#0 pointer type STRUCT bpf_dynptr_kern points to
  

unsupported dynamic pointer type"},

• {"not_valid_dynptr",

• "arg#0 pointer type STRUCT bpf_dynptr_kern must be valid and
  

initialized"},

• {"not_ptr_to_stack", "arg#0 pointer type STRUCT bpf_dynptr_kern

not to stack"}, +};

+static bool kfunc_not_supported;

+static int libbpf_print_cb(enum libbpf_print_level level, const char *fmt,

• 	   va_list args)
  

+{

• if (strcmp(fmt, "libbpf: extern (func ksym) '%s': not found in

kernel or module BTFs\n"))

• return 0;
  

• if (strcmp(va_arg(args, char *), "bpf_verify_pkcs7_signature"))

• return 0;
  

• kfunc_not_supported = true;
• return 0;

+}

+static void verify_fail(const char *prog_name, const char *expected_err_msg) +{

• struct test_kfunc_dynptr_param *skel;
• LIBBPF_OPTS(bpf_object_open_opts, opts);
• libbpf_print_fn_t old_print_cb;
• struct bpf_program *prog;
• int err;
• opts.kernel_log_buf = obj_log_buf;
• opts.kernel_log_size = log_buf_sz;
• opts.kernel_log_level = 1;
• skel = test_kfunc_dynptr_param__open_opts(&opts);
• if (!ASSERT_OK_PTR(skel, "test_kfunc_dynptr_param__open_opts"))

• goto cleanup;
  

• prog = bpf_object__find_program_by_name(skel->obj, prog_name);
• if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))

• goto cleanup;
  

• bpf_program__set_autoload(prog, true);
• bpf_map__set_max_entries(skel->maps.ringbuf, getpagesize());
• kfunc_not_supported = false;
• old_print_cb = libbpf_set_print(libbpf_print_cb);
• err = test_kfunc_dynptr_param__load(skel);
• libbpf_set_print(old_print_cb);
• if (err < 0 && kfunc_not_supported) {

• fprintf(stderr,
  

•   "%s:SKIP:bpf_verify_pkcs7_signature() kfunc not
  

supported\n",

•   __func__);
  

• test__skip();
  

• goto cleanup;
  

• }
• if (!ASSERT_ERR(err, "unexpected load success"))

• goto cleanup;
  

• if (!ASSERT_OK_PTR(strstr(obj_log_buf, expected_err_msg),

"expected_err_msg")) {

• fprintf(stderr, "Expected err_msg: %s\n",
  

expected_err_msg);

• fprintf(stderr, "Verifier output: %s\n", obj_log_buf);
  

• }

+cleanup:

• test_kfunc_dynptr_param__destroy(skel);

+}

+void test_kfunc_dynptr_param(void) +{

• int i;
• for (i = 0; i < ARRAY_SIZE(kfunc_dynptr_tests); i++) {

• if
  

(!test__start_subtest(kfunc_dynptr_tests[i].prog_name))

• 	continue;
  

• verify_fail(kfunc_dynptr_tests[i].prog_name,
  

• 	    kfunc_dynptr_tests[i].expected_err_msg);
  

• }

+} diff --git a/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c b/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c new file mode 100644 index 000000000000..2f09f91a1576 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0

+/*

• • Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
• • Author: Roberto Sassu roberto.sassu@huawei.com
• */

+#include "vmlinux.h" +#include <errno.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h>

+struct bpf_dynptr {

• __u64 :64;
• __u64 :64;

+} __attribute__((aligned(8)));

+extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,

• 		      struct bpf_dynptr *sig_ptr,
  

• 		      struct bpf_key *trusted_keyring)
  

__ksym;

+struct {

• __uint(type, BPF_MAP_TYPE_RINGBUF);

+} ringbuf SEC(".maps");

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

+SEC("?lsm.s/bpf") +int BPF_PROG(dynptr_type_not_supp, int cmd, union bpf_attr *attr,

•     unsigned int size)
  

+{

• char write_data[64] = "hello there, world!!";
• struct bpf_dynptr ptr;
• bpf_ringbuf_reserve_dynptr(&ringbuf, sizeof(write_data), 0,

&ptr);

• return bpf_verify_pkcs7_signature(&ptr, &ptr, NULL);

+}

+SEC("?lsm.s/bpf") +int BPF_PROG(not_valid_dynptr, int cmd, union bpf_attr *attr, unsigned int size) +{

• unsigned long val;
• return bpf_verify_pkcs7_signature((struct bpf_dynptr *)&val,

• 			  (struct bpf_dynptr *)&val,
  

NULL); +}

+SEC("?lsm.s/bpf") +int BPF_PROG(not_ptr_to_stack, int cmd, union bpf_attr *attr, unsigned int size) +{

• unsigned long val;
• return bpf_verify_pkcs7_signature((struct bpf_dynptr *)val,

• 			  (struct bpf_dynptr *)val,
  

NULL); +}