[PATCH v6 11/17] seltests/landlock: adds tests for bind() hooks

[Konstantin Meskhidze]

Adds selftests for bind() socket action.
The first is with no landlock restrictions:
    - bind without restrictions for ip4;
    - bind without restrictions for ip6;
The second ones is with mixed landlock rules:
    - bind with restrictions for ip4;
    - bind with restrictions for ip6;

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze at huawei.com>
---

Changes since v5:
* Splits commit.
* Adds local address 127.0.0.1.
* Adds FIXTURE_VARIANT and FIXTURE_VARIANT_ADD
helpers to support both ip4 and ip6 family tests and
shorten the code.
* Adds create_socket_variant() and bind_variant() helpers.
* Gets rid of reuse_addr variable in create_socket_variant.
* Formats code with clang-format-14.

Changes since v4:
* Adds port[MAX_SOCKET_NUM], struct sockaddr_in addr4
and struct sockaddr_in addr6 in FIXTURE.
* Refactors FIXTURE_SETUP:
    - initializing self->port, self->addr4 and self->addr6.
    - adding network namespace.
* Refactors code with self->port, self->addr4 and
self->addr6 variables.
* Adds selftests for IP6 family:
    - bind_no_restrictions_ip6.
    - bind_with_restrictions_ip6.
* Refactors selftests/landlock/config
* Moves enforce_ruleset() into common.h

Changes since v3:
* Split commit.
* Add helper create_socket.
* Add FIXTURE_SETUP.

---
 tools/testing/selftests/landlock/config     |   4 +
 tools/testing/selftests/landlock/net_test.c | 180 ++++++++++++++++++++
 2 files changed, 184 insertions(+)
 create mode 100644 tools/testing/selftests/landlock/net_test.c

diff --git a/tools/testing/selftests/landlock/config b/tools/testing/selftests/landlock/config
index 0f0a65287bac..71f7e9a8a64c 100644
--- a/tools/testing/selftests/landlock/config
+++ b/tools/testing/selftests/landlock/config
@@ -1,3 +1,7 @@
+CONFIG_INET=y
+CONFIG_IPV6=y
+CONFIG_NET=y
+CONFIG_NET_NS=y
 CONFIG_OVERLAY_FS=y
 CONFIG_SECURITY_LANDLOCK=y
 CONFIG_SECURITY_PATH=y
diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
new file mode 100644
index 000000000000..a0e02b6bd79f
--- /dev/null
+++ b/tools/testing/selftests/landlock/net_test.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock tests - Network
+ *
+ * Copyright (C) 2022 Huawei Tech. Co., Ltd.
+ */
+
+#define _GNU_SOURCE
+#include <arpa/inet.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/landlock.h>
+#include <netinet/in.h>
+#include <sched.h>
+#include <string.h>
+#include <sys/prctl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include "common.h"
+
+#define MAX_SOCKET_NUM 10
+
+#define SOCK_PORT_START 3470
+#define SOCK_PORT_ADD 10
+
+#define IP_ADDRESS "127.0.0.1"
+
+FIXTURE(socket)
+{
+	uint port[MAX_SOCKET_NUM];
+	struct sockaddr_in addr4[MAX_SOCKET_NUM];
+	struct sockaddr_in6 addr6[MAX_SOCKET_NUM];
+};
+
+FIXTURE_VARIANT(socket)
+{
+	const bool is_ipv4;
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(socket, ipv4) {
+	/* clang-format on */
+	.is_ipv4 = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(socket, ipv6) {
+	/* clang-format on */
+	.is_ipv4 = false,
+};
+
+static int create_socket_variant(const FIXTURE_VARIANT(socket) * const variant,
+				 const int type)
+{
+	if (variant->is_ipv4)
+		return socket(AF_INET, type | SOCK_CLOEXEC, 0);
+	else
+		return socket(AF_INET6, type | SOCK_CLOEXEC, 0);
+}
+
+static int bind_variant(const FIXTURE_VARIANT(socket) * const variant,
+			const int sockfd,
+			const FIXTURE_DATA(socket) * const self,
+			const size_t index)
+{
+	if (variant->is_ipv4)
+		return bind(sockfd, &self->addr4[index],
+			    sizeof(self->addr4[index]));
+	else
+		return bind(sockfd, &self->addr6[index],
+			    sizeof(self->addr6[index]));
+}
+
+FIXTURE_SETUP(socket)
+{
+	int i;
+	/* Creates IP4 socket addresses. */
+	for (i = 0; i < MAX_SOCKET_NUM; i++) {
+		self->port[i] = SOCK_PORT_START + SOCK_PORT_ADD * i;
+		self->addr4[i].sin_family = AF_INET;
+		self->addr4[i].sin_port = htons(self->port[i]);
+		self->addr4[i].sin_addr.s_addr = inet_addr(IP_ADDRESS);
+		memset(&(self->addr4[i].sin_zero), '\0', 8);
+	}
+
+	/* Creates IP6 socket addresses. */
+	for (i = 0; i < MAX_SOCKET_NUM; i++) {
+		self->port[i] = SOCK_PORT_START + SOCK_PORT_ADD * i;
+		self->addr6[i].sin6_family = AF_INET6;
+		self->addr6[i].sin6_port = htons(self->port[i]);
+		inet_pton(AF_INET6, IP_ADDRESS, &(self->addr6[i].sin6_addr));
+	}
+
+	set_cap(_metadata, CAP_SYS_ADMIN);
+	ASSERT_EQ(0, unshare(CLONE_NEWNET));
+	ASSERT_EQ(0, system("ip link set dev lo up"));
+	clear_cap(_metadata, CAP_SYS_ADMIN);
+}
+
+FIXTURE_TEARDOWN(socket)
+{
+}
+
+TEST_F(socket, bind_no_restrictions)
+{
+	int sockfd;
+
+	sockfd = create_socket_variant(variant, SOCK_STREAM);
+	ASSERT_LE(0, sockfd);
+
+	/* Binds a socket to port[0]. */
+	ASSERT_EQ(0, bind_variant(variant, sockfd, self, 0));
+
+	ASSERT_EQ(0, close(sockfd));
+}
+
+TEST_F(socket, bind_with_restrictions)
+{
+	int sockfd;
+
+	struct landlock_ruleset_attr ruleset_attr = {
+		.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
+				      LANDLOCK_ACCESS_NET_CONNECT_TCP,
+	};
+	struct landlock_net_service_attr net_service_1 = {
+		.allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP |
+				  LANDLOCK_ACCESS_NET_CONNECT_TCP,
+		.port = self->port[0],
+	};
+	struct landlock_net_service_attr net_service_2 = {
+		.allowed_access = LANDLOCK_ACCESS_NET_CONNECT_TCP,
+		.port = self->port[1],
+	};
+	struct landlock_net_service_attr net_service_3 = {
+		.allowed_access = 0,
+		.port = self->port[2],
+	};
+
+	const int ruleset_fd =
+		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
+	ASSERT_LE(0, ruleset_fd);
+
+	/* Allows connect and bind operations to the port[0] socket. */
+	ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
+				       &net_service_1, 0));
+	/* Allows connect and deny bind operations to the port[1] socket. */
+	ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
+				       &net_service_2, 0));
+	/* Empty allowed_access (i.e. deny rules) are ignored in network actions
+	 * for port[2] socket.
+	 */
+	ASSERT_EQ(-1, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
+					&net_service_3, 0));
+	ASSERT_EQ(ENOMSG, errno);
+
+	/* Enforces the ruleset. */
+	enforce_ruleset(_metadata, ruleset_fd);
+
+	sockfd = create_socket_variant(variant, SOCK_STREAM);
+	ASSERT_LE(0, sockfd);
+	/* Binds a socket to port[0]. */
+	ASSERT_EQ(0, bind_variant(variant, sockfd, self, 0));
+
+	/* Close bounded socket. */
+	ASSERT_EQ(0, close(sockfd));
+
+	sockfd = create_socket_variant(variant, SOCK_STREAM);
+	ASSERT_LE(0, sockfd);
+	/* Binds a socket to port[1]. */
+	ASSERT_EQ(-1, bind_variant(variant, sockfd, self, 1));
+	ASSERT_EQ(EACCES, errno);
+
+	sockfd = create_socket_variant(variant, SOCK_STREAM);
+	ASSERT_LE(0, sockfd);
+	/* Binds a socket to port[2]. */
+	ASSERT_EQ(-1, bind_variant(variant, sockfd, self, 2));
+	ASSERT_EQ(EACCES, errno);
+}
+TEST_HARNESS_MAIN
--
2.25.1