1 files changed, 399 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c b/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c
new file mode 100644
index 000000000000..579d6ee83ce0
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c
@@ -0,0 +1,399 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <endian.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <sys/mman.h>
+#include <linux/keyctl.h>
+#include <test_progs.h>
+
+#include "test_verify_pkcs7_sig.skel.h"
+
+#define MAX_DATA_SIZE (1024 * 1024)
+#define MAX_SIG_SIZE 1024
+
+#define VERIFY_USE_SECONDARY_KEYRING (1UL)
+#define VERIFY_USE_PLATFORM_KEYRING  (2UL)
+
+/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */
+#define MODULE_SIG_STRING "~Module signature appended~\n"
+
+/*
+ * Module signature information block.
+ *
+ * The constituents of the signature section are, in order:
+ *
+ *	- Signer's name
+ *	- Key identifier
+ *	- Signature data
+ *	- Information block
+ */
+struct module_signature {
+	__u8	algo;		/* Public-key crypto algorithm [0] */
+	__u8	hash;		/* Digest algorithm [0] */
+	__u8	id_type;	/* Key identifier type [PKEY_ID_PKCS7] */
+	__u8	signer_len;	/* Length of signer's name [0] */
+	__u8	key_id_len;	/* Length of key identifier [0] */
+	__u8	__pad[3];
+	__be32	sig_len;	/* Length of signature data */
+};
+
+struct data {
+	__u8 data[MAX_DATA_SIZE];
+	__u32 data_len;
+	__u8 sig[MAX_SIG_SIZE];
+	__u32 sig_len;
+};
+
+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 int _run_setup_process(const char *setup_dir, const char *cmd)
+{
+	int child_pid, child_status;
+
+	child_pid = fork();
+	if (child_pid == 0) {
+		execlp("./verify_sig_setup.sh", "./verify_sig_setup.sh", cmd,
+		       setup_dir, NULL);
+		exit(errno);
+
+	} else if (child_pid > 0) {
+		waitpid(child_pid, &child_status, 0);
+		return WEXITSTATUS(child_status);
+	}
+
+	return -EINVAL;
+}
+
+static int populate_data_item_str(const char *tmp_dir, struct data *data_item)
+{
+	struct stat st;
+	char data_template[] = "/tmp/dataXXXXXX";
+	char path[PATH_MAX];
+	int ret, fd, child_status, child_pid;
+
+	data_item->data_len = 4;
+	memcpy(data_item->data, "test", data_item->data_len);
+
+	fd = mkstemp(data_template);
+	if (fd == -1)
+		return -errno;
+
+	ret = write(fd, data_item->data, data_item->data_len);
+
+	close(fd);
+
+	if (ret != data_item->data_len) {
+		ret = -EIO;
+		goto out;
+	}
+
+	child_pid = fork();
+
+	if (child_pid == -1) {
+		ret = -errno;
+		goto out;
+	}
+
+	if (child_pid == 0) {
+		snprintf(path, sizeof(path), "%s/signing_key.pem", tmp_dir);
+
+		return execlp("./sign-file", "./sign-file", "-d", "sha256",
+			      path, path, data_template, NULL);
+	}
+
+	waitpid(child_pid, &child_status, 0);
+
+	ret = WEXITSTATUS(child_status);
+	if (ret)
+		goto out;
+
+	snprintf(path, sizeof(path), "%s.p7s", data_template);
+
+	ret = stat(path, &st);
+	if (ret == -1) {
+		ret = -errno;
+		goto out;
+	}
+
+	if (st.st_size > sizeof(data_item->sig)) {
+		ret = -EINVAL;
+		goto out_sig;
+	}
+
+	data_item->sig_len = st.st_size;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1) {
+		ret = -errno;
+		goto out_sig;
+	}
+
+	ret = read(fd, data_item->sig, data_item->sig_len);
+
+	close(fd);
+
+	if (ret != data_item->sig_len) {
+		ret = -EIO;
+		goto out_sig;
+	}
+
+	ret = 0;
+out_sig:
+	unlink(path);
+out:
+	unlink(data_template);
+	return ret;
+}
+
+static int populate_data_item_mod(struct data *data_item)
+{
+	char mod_path[PATH_MAX], *mod_path_ptr;
+	struct stat st;
+	void *mod;
+	FILE *fp;
+	struct module_signature ms;
+	int ret, fd, modlen, marker_len, sig_len;
+
+	data_item->data_len = 0;
+
+	if (stat("/lib/modules", &st) == -1)
+		return 0;
+
+	/* Requires CONFIG_TCP_CONG_BIC=m. */
+	fp = popen("find /lib/modules/$(uname -r) -name tcp_bic.ko", "r");
+	if (!fp)
+		return 0;
+
+	mod_path_ptr = fgets(mod_path, sizeof(mod_path), fp);
+	pclose(fp);
+
+	if (!mod_path_ptr)
+		return 0;
+
+	mod_path_ptr = strchr(mod_path, '\n');
+	if (!mod_path_ptr)
+		return 0;
+
+	*mod_path_ptr = '\0';
+
+	if (stat(mod_path, &st) == -1)
+		return 0;
+
+	modlen = st.st_size;
+	marker_len = sizeof(MODULE_SIG_STRING) - 1;
+
+	fd = open(mod_path, O_RDONLY);
+	if (fd == -1)
+		return -errno;
+
+	mod = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+
+	close(fd);
+
+	if (mod == MAP_FAILED)
+		return -errno;
+
+	if (strncmp(mod + modlen - marker_len, MODULE_SIG_STRING, marker_len)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	modlen -= marker_len;
+
+	memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));
+
+	sig_len = __be32_to_cpu(ms.sig_len);
+	modlen -= sig_len + sizeof(ms);
+
+	if (modlen > sizeof(data_item->data)) {
+		ret = -E2BIG;
+		goto out;
+	}
+
+	memcpy(data_item->data, mod, modlen);
+	data_item->data_len = modlen;
+
+	if (sig_len > sizeof(data_item->sig)) {
+		ret = -E2BIG;
+		goto out;
+	}
+
+	memcpy(data_item->sig, mod + modlen, sig_len);
+	data_item->sig_len = sig_len;
+	ret = 0;
+out:
+	munmap(mod, st.st_size);
+	return ret;
+}
+
+void test_verify_pkcs7_sig(void)
+{
+	libbpf_print_fn_t old_print_cb;
+	char tmp_dir_template[] = "/tmp/verify_sigXXXXXX";
+	char *tmp_dir;
+	struct test_verify_pkcs7_sig *skel = NULL;
+	struct bpf_map *map;
+	struct data data;
+	int ret, zero = 0;
+
+	/* Trigger creation of session keyring. */
+	syscall(__NR_request_key, "keyring", "_uid.0", NULL,
+		KEY_SPEC_SESSION_KEYRING);
+
+	tmp_dir = mkdtemp(tmp_dir_template);
+	if (!ASSERT_OK_PTR(tmp_dir, "mkdtemp"))
+		return;
+
+	ret = _run_setup_process(tmp_dir, "setup");
+	if (!ASSERT_OK(ret, "_run_setup_process"))
+		goto close_prog;
+
+	skel = test_verify_pkcs7_sig__open();
+	if (!ASSERT_OK_PTR(skel, "test_verify_pkcs7_sig__open"))
+		goto close_prog;
+
+	old_print_cb = libbpf_set_print(libbpf_print_cb);
+	ret = test_verify_pkcs7_sig__load(skel);
+	libbpf_set_print(old_print_cb);
+
+	if (ret < 0 && kfunc_not_supported) {
+		printf(
+		  "%s:SKIP:bpf_verify_pkcs7_signature() kfunc not supported\n",
+		  __func__);
+		test__skip();
+		goto close_prog;
+	}
+
+	if (!ASSERT_OK(ret, "test_verify_pkcs7_sig__load"))
+		goto close_prog;
+
+	ret = test_verify_pkcs7_sig__attach(skel);
+	if (!ASSERT_OK(ret, "test_verify_pkcs7_sig__attach"))
+		goto close_prog;
+
+	map = bpf_object__find_map_by_name(skel->obj, "data_input");
+	if (!ASSERT_OK_PTR(map, "data_input not found"))
+		goto close_prog;
+
+	skel->bss->monitored_pid = getpid();
+
+	/* Test without data and signature. */
+	skel->bss->user_keyring_serial = KEY_SPEC_SESSION_KEYRING;
+
+	ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY);
+	if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input"))
+		goto close_prog;
+
+	/* Test successful signature verification with session keyring. */
+	ret = populate_data_item_str(tmp_dir, &data);
+	if (!ASSERT_OK(ret, "populate_data_item_str"))
+		goto close_prog;
+
+	ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY);
+	if (!ASSERT_OK(ret, "bpf_map_update_elem data_input"))
+		goto close_prog;
+
+	/* Test successful signature verification with testing keyring. */
+	skel->bss->user_keyring_serial = syscall(__NR_request_key, "keyring",
+						 "ebpf_testing_keyring", NULL,
+						 KEY_SPEC_SESSION_KEYRING);
+
+	ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY);
+	if (!ASSERT_OK(ret, "bpf_map_update_elem data_input"))
+		goto close_prog;
+
+	/*
+	 * Ensure key_task_permission() is called and rejects the keyring
+	 * (no Search permission).
+	 */
+	syscall(__NR_keyctl, KEYCTL_SETPERM, skel->bss->user_keyring_serial,
+		0x37373737);
+
+	ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY);
+	if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input"))
+		goto close_prog;
+
+	syscall(__NR_keyctl, KEYCTL_SETPERM, skel->bss->user_keyring_serial,
+		0x3f3f3f3f);
+
+	/*
+	 * Ensure key_validate() is called and rejects the keyring (key expired)
+	 */
+	syscall(__NR_keyctl, KEYCTL_SET_TIMEOUT,
+		skel->bss->user_keyring_serial, 1);
+	sleep(1);
+
+	ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY);
+	if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input"))
+		goto close_prog;
+
+	skel->bss->user_keyring_serial = KEY_SPEC_SESSION_KEYRING;
+
+	/* Test with corrupted data (signature verification should fail). */
+	data.data[0] = 'a';
+	ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data, BPF_ANY);
+	if (!ASSERT_LT(ret, 0, "bpf_map_update_elem data_input"))
+		goto close_prog;
+
+	ret = populate_data_item_mod(&data);
+	if (!ASSERT_OK(ret, "populate_data_item_mod"))
+		goto close_prog;
+
+	/* Test signature verification with system keyrings. */
+	if (data.data_len) {
+		skel->bss->user_keyring_serial = 0;
+		skel->bss->system_keyring_id = 0;
+
+		ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data,
+					  BPF_ANY);
+		if (!ASSERT_OK(ret, "bpf_map_update_elem data_input"))
+			goto close_prog;
+
+		skel->bss->system_keyring_id = VERIFY_USE_SECONDARY_KEYRING;
+
+		ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data,
+					  BPF_ANY);
+		if (!ASSERT_OK(ret, "bpf_map_update_elem data_input"))
+			goto close_prog;
+
+		skel->bss->system_keyring_id = VERIFY_USE_PLATFORM_KEYRING;
+
+		ret = bpf_map_update_elem(bpf_map__fd(map), &zero, &data,
+					  BPF_ANY);
+		ASSERT_LT(ret, 0, "bpf_map_update_elem data_input");
+	}
+
+close_prog:
+	_run_setup_process(tmp_dir, "cleanup");
+
+	if (!skel)
+		return;
+
+	skel->bss->monitored_pid = 0;
+	test_verify_pkcs7_sig__destroy(skel);
+}