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Message-Id: <20220920075951.929132-14-roberto.sassu@huaweicloud.com>
Date: Tue, 20 Sep 2022 09:59:51 +0200
From: Roberto Sassu <roberto.sassu@...weicloud.com>
To: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
martin.lau@...ux.dev, song@...nel.org, yhs@...com,
john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
haoluo@...gle.com, jolsa@...nel.org, mykolal@...com,
dhowells@...hat.com, jarkko@...nel.org, rostedt@...dmis.org,
mingo@...hat.com, paul@...l-moore.com, jmorris@...ei.org,
serge@...lyn.com, shuah@...nel.org
Cc: bpf@...r.kernel.org, keyrings@...r.kernel.org,
linux-security-module@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
deso@...teo.net, memxor@...il.com,
Roberto Sassu <roberto.sassu@...wei.com>
Subject: [PATCH v18 13/13] selftests/bpf: Add tests for dynamic pointers parameters in kfuncs
From: Roberto Sassu <roberto.sassu@...wei.com>
Add tests to ensure that only supported dynamic pointer types are accepted,
that the passed argument is actually a dynamic pointer, that the passed
argument is a pointer to the stack, and that bpf_verify_pkcs7_signature()
correctly handles dynamic pointers with data set to NULL.
The tests are currently in the deny list for s390x (JIT does not support
calling kernel function).
Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@...il.com>
---
tools/testing/selftests/bpf/DENYLIST.s390x | 1 +
.../bpf/prog_tests/kfunc_dynptr_param.c | 164 ++++++++++++++++++
.../bpf/progs/test_kfunc_dynptr_param.c | 94 ++++++++++
3 files changed, 259 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/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x
index 759b2bb53b53..5fc7d0de19f3 100644
--- a/tools/testing/selftests/bpf/DENYLIST.s390x
+++ b/tools/testing/selftests/bpf/DENYLIST.s390x
@@ -73,3 +73,4 @@ htab_update # failed to attach: ERROR: strerror_r(-
tracing_struct # failed to auto-attach: -524 (trampoline)
lookup_key # JIT does not support calling kernel function (kfunc)
verify_pkcs7_sig # JIT does not support calling kernel function (kfunc)
+kfunc_dynptr_param # JIT does not support calling kernel function (kfunc)
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..c210657d4d0a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/kfunc_dynptr_param.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (c) 2022 Facebook
+ * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@...wei.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_verifier_err_msg;
+ int expected_runtime_err;
+} kfunc_dynptr_tests[] = {
+ {"dynptr_type_not_supp",
+ "arg#0 pointer type STRUCT bpf_dynptr_kern points to unsupported dynamic pointer type", 0},
+ {"not_valid_dynptr",
+ "arg#0 pointer type STRUCT bpf_dynptr_kern must be valid and initialized", 0},
+ {"not_ptr_to_stack", "arg#0 pointer type STRUCT bpf_dynptr_kern not to stack", 0},
+ {"dynptr_data_null", NULL, -EBADMSG},
+};
+
+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);
+}
+
+static void verify_success(const char *prog_name, int expected_runtime_err)
+{
+ struct test_kfunc_dynptr_param *skel;
+ libbpf_print_fn_t old_print_cb;
+ struct bpf_program *prog;
+ struct bpf_link *link;
+ __u32 next_id;
+ int err;
+
+ skel = test_kfunc_dynptr_param__open();
+ if (!ASSERT_OK_PTR(skel, "test_kfunc_dynptr_param__open"))
+ return;
+
+ skel->bss->pid = getpid();
+
+ 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_OK(err, "test_kfunc_dynptr_param__load"))
+ 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;
+
+ link = bpf_program__attach(prog);
+ if (!ASSERT_OK_PTR(link, "bpf_program__attach"))
+ goto cleanup;
+
+ err = bpf_prog_get_next_id(0, &next_id);
+
+ bpf_link__destroy(link);
+
+ if (!ASSERT_OK(err, "bpf_prog_get_next_id"))
+ goto cleanup;
+
+ ASSERT_EQ(skel->bss->err, expected_runtime_err, "err");
+
+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;
+
+ if (kfunc_dynptr_tests[i].expected_verifier_err_msg)
+ verify_fail(kfunc_dynptr_tests[i].prog_name,
+ kfunc_dynptr_tests[i].expected_verifier_err_msg);
+ else
+ verify_success(kfunc_dynptr_tests[i].prog_name,
+ kfunc_dynptr_tests[i].expected_runtime_err);
+ }
+}
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..ce39d096bba3
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@...wei.com>
+ */
+
+#include "vmlinux.h"
+#include <errno.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
+extern void bpf_key_put(struct bpf_key *key) __ksym;
+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");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, __u32);
+} array_map SEC(".maps");
+
+int err, pid;
+
+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);
+}
+
+SEC("lsm.s/bpf")
+int BPF_PROG(dynptr_data_null, int cmd, union bpf_attr *attr, unsigned int size)
+{
+ struct bpf_key *trusted_keyring;
+ struct bpf_dynptr ptr;
+ __u32 *value;
+ int ret, zero = 0;
+
+ if (bpf_get_current_pid_tgid() >> 32 != pid)
+ return 0;
+
+ value = bpf_map_lookup_elem(&array_map, &zero);
+ if (!value)
+ return 0;
+
+ /* Pass invalid flags. */
+ ret = bpf_dynptr_from_mem(value, sizeof(*value), ((__u64)~0ULL), &ptr);
+ if (ret != -EINVAL)
+ return 0;
+
+ trusted_keyring = bpf_lookup_system_key(0);
+ if (!trusted_keyring)
+ return 0;
+
+ err = bpf_verify_pkcs7_signature(&ptr, &ptr, trusted_keyring);
+
+ bpf_key_put(trusted_keyring);
+
+ return 0;
+}
--
2.25.1
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