[RFC PATCH 2/2] landlock: selftests for bind and connect hooks
Konstantin Meskhidze
konstantin.meskhidze at huawei.com
Mon Feb 7 07:11:08 UTC 2022
2/1/2022 9:31 PM, Mickaël Salaün пишет:
>
> On 24/01/2022 09:02, Konstantin Meskhidze wrote:
>> Support 4 tests for bind and connect networks actions:
>
> Good to see such tests!
>
>
>> 1. bind() a socket with no landlock restrictions.
>> 2. bind() sockets with landllock restrictions.
>
> You can leverage the FIXTURE_VARIANT helpers to factor out this kind of
> tests (see ptrace_test.c).
Thanks. I will check this out.
>
>
>> 3. connect() a socket to listening one with no landlock restricitons.
>> 4. connect() sockets with landlock restrictions.
>
> Same here, you can factor out code. I guess you could create helpers for
> client and server parts.
Ok. I got it.
>
> We also need to test with IPv4, IPv6 and the AF_UNSPEC tricks.
Yep. I will add AF_UNSPEC case.
>
> Please provide the kernel test coverage and explain why the uncovered
> code cannot be covered:
> https://www.kernel.org/doc/html/latest/dev-tools/gcov.html
Thanks for the link. I will check it out.
>
> You'll probably see that there are a multiple parts of the kernel that
> are not covered. For instance, it is important to test different
> combinations of layered network rules (see layout1/ruleset_overlap,
> layer_rule_unions, non_overlapping_accesses,
> interleaved_masked_accesses… in fs_test.c). Tests in fs_test.c are more
> complex because handling file system rules is more complex, but you can
> get some inspiration in it, especially the edge cases.
I got your point. I agree that we need to cover as many network rules
combinations as possible.
>
> We also need to test invalid user space supplied data (see layout1/inval
> test in fs_test.c).
Ok. I will add this kind of test. Thanks.
>
>
>>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze at huawei.com>
>> ---
>> .../testing/selftests/landlock/network_test.c | 346 ++++++++++++++++++
>> 1 file changed, 346 insertions(+)
>> create mode 100644 tools/testing/selftests/landlock/network_test.c
>>
>> diff --git a/tools/testing/selftests/landlock/network_test.c
>> b/tools/testing/selftests/landlock/network_test.c
>> new file mode 100644
>> index 000000000000..9dfe37a2fb20
>> --- /dev/null
>> +++ b/tools/testing/selftests/landlock/network_test.c
>> @@ -0,0 +1,346 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Landlock tests - Common user space base
>> + *
>> + * Copyright © 2017-2020 Mickaël Salaün <mic at digikod.net>
>> + * Copyright © 2019-2020 ANSSI
>
> You need to update this header with an appropriate description and the
> copyright holder (your employer).
>
Ok. I got it.
>
>> + */
>> +
>> +#define _GNU_SOURCE
>> +#include <errno.h>
>> +#include <fcntl.h>
>> +#include <linux/landlock.h>
>> +#include <string.h>
>> +#include <sys/prctl.h>
>> +#include <sys/socket.h>
>> +#include <sys/types.h>
>> +#include <netinet/in.h>
>> +#include <arpa/inet.h>
>
> To make it determinisitic (and ease patching/diff/merging), you should
> sort all the included files (in tests and in the kernel code).
Sorry. Did not get your point here. Could you explain in a bit more
details please.
>
>
>> +
>> +#include "common.h"
>> +
>> +#define SOCK_PORT_1 3470
>> +#define SOCK_PORT_2 3480
>> +#define SOCK_PORT_3 3490
>
> To avoid port collision and create a clean and stable test environement
> (to avoid flaky tests), you should create a network namespace with
> FIXTURE_SETUP, test with TEST_F_FORK (to not polute the parent process,
> and which works with test variants), and use the set_cap and clear_cap
> helpers (see fs_test.c).
Ok. I got it.
>
>
>> +
>> +#define IP_ADDRESS "127.0.0.1"
>> +
>> +/* Number pending connections queue tobe hold */
>> +#define BACKLOG 10
>> +
>> +TEST(socket_bind_no_restrictions) {
>> +
>> + int sockfd;
>> + struct sockaddr_in addr;
>> + const int one = 1;
>> +
>> + /* Create a socket */
>> + sockfd = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, sockfd);
>> + /* Allow reuse of local addresses */
>> + ASSERT_EQ(0, setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &one,
>> sizeof(one)));
>
> With a dedicated namespace, SO_REUSEADDR should not be required.
Yes. I agree. Will be refactored.
>
>
>> +
>> + /* Set socket address parameters */
>> + addr.sin_family = AF_INET;
>> + addr.sin_port = htons(SOCK_PORT_1);
>> + addr.sin_addr.s_addr = inet_addr(IP_ADDRESS);
>> + memset(&(addr.sin_zero), '\0', 8);
>> +
>> + /* Bind the socket to IP address */
>> + ASSERT_EQ(0, bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)));
>> +}
>> +
>> +TEST(sockets_bind_with_restrictions) {
>> +
>> + int sockfd_1, sockfd_2, sockfd_3;
>> + struct sockaddr_in addr_1, addr_2, addr_3;
>> + const int one = 1;
>> +
>> + 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 = SOCK_PORT_1,
>> + };
>> + struct landlock_net_service_attr net_service_2 = {
>> + .allowed_access = LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + .port = SOCK_PORT_2,
>> + };
>> + struct landlock_net_service_attr net_service_3 = {
>> + .allowed_access = 0,
>> + .port = SOCK_PORT_3,
>> + };
>
> Good to have these three different rules!
>
>
>> +
>> + const int ruleset_fd = landlock_create_ruleset(&ruleset_attr,
>> + sizeof(ruleset_attr), 0);
>> + ASSERT_LE(0, ruleset_fd);
>> +
>> + /* Allow connect and bind operations to the SOCK_PORT_1 socket
>> "object" */
>
> You can omit "object" but use full sentences at the third person
> (because it explains what do the next lines).
Ok. I got it.
>
>
>> + ASSERT_EQ(0, landlock_add_rule(ruleset_fd,
>> LANDLOCK_RULE_NET_SERVICE,
>> + &net_service_1, 0));
>> + /* Allow connect and deny bind operations to the SOCK_PORT_2
>> socket "object" */
>> + 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 SOCK_PORT_3 socket "object"
>> + */
>> + ASSERT_EQ(-1, landlock_add_rule(ruleset_fd,
>> LANDLOCK_RULE_NET_SERVICE,
>> + &net_service_3, 0));
>> + ASSERT_EQ(ENOMSG, errno);
>> +
>> + /* Enforces the ruleset. */
>> + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));
>> + ASSERT_EQ(0, landlock_restrict_self(ruleset_fd, 0));
>> + ASSERT_EQ(0, close(ruleset_fd));
>> +
>> + /* Create a socket 1 */
>> + sockfd_1 = socket(AF_INET, SOCK_STREAM, 0);
>
> Please create all FD with SOCK_CLOEXEC and also close them when not
> needed. This could also reduce the number of FD.
Ok. Thanks for noticing. It makes sense.
>
>
>> + ASSERT_LE(0, sockfd_1);
>> + /* Allow reuse of local addresses */
>> + ASSERT_EQ(0, setsockopt(sockfd_1, SOL_SOCKET, SO_REUSEADDR, &one,
>> sizeof(one)));
>> +
>> + /* Set socket 1 address parameters */
>> + addr_1.sin_family = AF_INET;
>> + addr_1.sin_port = htons(SOCK_PORT_1);
>> + addr_1.sin_addr.s_addr = inet_addr(IP_ADDRESS);
>> + memset(&(addr_1.sin_zero), '\0', 8);
>> + /* Bind the socket 1 to IP address */
>> + ASSERT_EQ(0, bind(sockfd_1, (struct sockaddr *)&addr_1,
>> sizeof(addr_1)));
>> +
>> + /* Create a socket 2 */
>> + sockfd_2 = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, sockfd_2);
>> + /* Allow reuse of local addresses */
>> + ASSERT_EQ(0, setsockopt(sockfd_2, SOL_SOCKET, SO_REUSEADDR, &one,
>> sizeof(one)));
>> +
>> + /* Set socket 2 address parameters */
>> + addr_2.sin_family = AF_INET;
>> + addr_2.sin_port = htons(SOCK_PORT_2);
>> + addr_2.sin_addr.s_addr = inet_addr(IP_ADDRESS);
>> + memset(&(addr_2.sin_zero), '\0', 8);
>
> These part could be factored out with helpers or/and test variants.
Thanks. Will be factored out.
>
>
>> + /* Bind the socket 2 to IP address */
>> + ASSERT_EQ(-1, bind(sockfd_2, (struct sockaddr *)&addr_2,
>> sizeof(addr_2)));
>> + ASSERT_EQ(EACCES, errno);
>> +
>> + /* Create a socket 3 */
>> + sockfd_3 = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, sockfd_3);
>> + /* Allow reuse of local addresses */
>> + ASSERT_EQ(0, setsockopt(sockfd_3, SOL_SOCKET, SO_REUSEADDR, &one,
>> sizeof(one)));
>> +
>> + /* Set socket 3 address parameters */
>> + addr_3.sin_family = AF_INET;
>> + addr_3.sin_port = htons(SOCK_PORT_3);
>> + addr_3.sin_addr.s_addr = inet_addr(IP_ADDRESS);
>> + memset(&(addr_3.sin_zero), '\0', 8);
>> + /* Bind the socket 3 to IP address */
>> + ASSERT_EQ(0, bind(sockfd_3, (struct sockaddr *)&addr_3,
>> sizeof(addr_3)));
>
> Why is it allowed to bind to SOCK_PORT_3 whereas net_service_3 forbids it?
It's allowed cause net_service_3 has empty access field.
/* Empty allowed_access (i.e. deny rules) are ignored in network
* actions for SOCK_PORT_3 socket "object"
*/
ASSERT_EQ(-1, landlock_add_rule(ruleset_fd,
LANDLOCK_RULE_NET_SERVICE,
&net_service_3, 0));
ASSERT_EQ(ENOMSG, errno);
Applying this rule returns ENOMSG errno:
/* Informs about useless rule: empty allowed_access (i.e. deny rules)
* are ignored in network actions
*/
if (!net_service_attr.allowed_access) {
err = -ENOMSG;
goto out_put_ruleset;
}
This means binding socket 3 is not restricted.
For path_beneath_attr.allowed_access = 0 there is the same logic.
>
>
>> +}
>> +
>> +TEST(socket_connect_no_restrictions) {
>> +
>> + int sockfd, new_fd;
>> + struct sockaddr_in addr;
>> + pid_t child;
>> + int status;
>> + const int one = 1;
>> +
>> + /* Create a server socket */
>> + sockfd = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, sockfd);
>> + /* Allow reuse of local addresses */
>> + ASSERT_EQ(0, setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &one,
>> sizeof(one)));
>> +
>> + /* Set socket address parameters */
>> + addr.sin_family = AF_INET;
>> + addr.sin_port = htons(SOCK_PORT_1);
>> + addr.sin_addr.s_addr = inet_addr(IP_ADDRESS);
>> + memset(&(addr.sin_zero), '\0', 8);
>> +
>> + /* Bind the socket to IP address */
>> + ASSERT_EQ(0, bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)));
>> +
>> + /* Make listening socket */
>> + ASSERT_EQ(0, listen(sockfd, BACKLOG));
>> +
>> + child = fork();
>> + ASSERT_LE(0, child);
>> + if (child == 0) {
>> + int child_sockfd;
>> + struct sockaddr_in connect_addr;
>> +
>> + /* Close listening socket for the child */
>> + ASSERT_EQ(0, close(sockfd));
>> + /* Create a stream client socket */
>> + child_sockfd = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, child_sockfd);
>> +
>> + /* Set server's socket address parameters*/
>> + connect_addr.sin_family = AF_INET;
>> + connect_addr.sin_port = htons(SOCK_PORT_1);
>> + connect_addr.sin_addr.s_addr = htonl(INADDR_ANY);
>> + memset(&(connect_addr.sin_zero), '\0', 8);
>> +
>> + /* Make connection to the listening socket */
>> + ASSERT_EQ(0, connect(child_sockfd, (struct sockaddr
>> *)&connect_addr,
>> + sizeof(struct sockaddr)));
>> + _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
>> + return;
>> + }
>> + /* Accept connection from the child */
>> + new_fd = accept(sockfd, NULL, 0);
>> + ASSERT_LE(0, new_fd);
>> +
>> + /* Close connection */
>> + ASSERT_EQ(0, close(new_fd));
>> +
>> + ASSERT_EQ(child, waitpid(child, &status, 0));
>> + ASSERT_EQ(1, WIFEXITED(status));
>> + ASSERT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));
>> +}
>> +
>> +TEST(sockets_connect_with_restrictions) {
>> +
>> + int new_fd;
>> + int sockfd_1, sockfd_2;
>> + struct sockaddr_in addr_1, addr_2;
>> + pid_t child_1, child_2;
>> + int status;
>> + const int one = 1;
>> +
>> + 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 = SOCK_PORT_1,
>> + };
>> + struct landlock_net_service_attr net_service_2 = {
>> + .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP,
>> + .port = SOCK_PORT_2,
>> + };
>> +
>> + const int ruleset_fd = landlock_create_ruleset(&ruleset_attr,
>> + sizeof(ruleset_attr), 0);
>> + ASSERT_LE(0, ruleset_fd);
>> +
>> + /* Allow connect and bind operations to the SOCK_PORT_1 socket
>> "object" */
>> + ASSERT_EQ(0, landlock_add_rule(ruleset_fd,
>> LANDLOCK_RULE_NET_SERVICE,
>> + &net_service_1, 0));
>> + /* Allow connect and deny bind operations to the SOCK_PORT_2
>> socket "object" */
>> + ASSERT_EQ(0, landlock_add_rule(ruleset_fd,
>> LANDLOCK_RULE_NET_SERVICE,
>> + &net_service_2, 0));
>> +
>> + /* Enforces the ruleset. */
>> + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));
>> + ASSERT_EQ(0, landlock_restrict_self(ruleset_fd, 0));
>> + ASSERT_EQ(0, close(ruleset_fd));
>> +
>> + /* Create a server socket 1 */
>> + sockfd_1 = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, sockfd_1);
>> + /* Allow reuse of local addresses */
>> + ASSERT_EQ(0, setsockopt(sockfd_1, SOL_SOCKET, SO_REUSEADDR, &one,
>> sizeof(one)));
>> +
>> + /* Set socket 1 address parameters */
>> + addr_1.sin_family = AF_INET;
>> + addr_1.sin_port = htons(SOCK_PORT_1);
>> + addr_1.sin_addr.s_addr = inet_addr(IP_ADDRESS);
>> + memset(&(addr_1.sin_zero), '\0', 8);
>> +
>> + /* Bind the socket 1 to IP address */
>> + ASSERT_EQ(0, bind(sockfd_1, (struct sockaddr *)&addr_1,
>> sizeof(addr_1)));
>> +
>> + /* Make listening socket 1 */
>> + ASSERT_EQ(0, listen(sockfd_1, BACKLOG));
>> +
>> + child_1 = fork();
>> + ASSERT_LE(0, child_1);
>> + if (child_1 == 0) {
>> + int child_sockfd;
>> + struct sockaddr_in connect_addr;
>> +
>> + /* Close listening socket for the child */
>> + ASSERT_EQ(0, close(sockfd_1));
>> + /* Create a stream client socket */
>> + child_sockfd = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, child_sockfd);
>> +
>> + /* Set server's socket 1 address parameters*/
>> + connect_addr.sin_family = AF_INET;
>> + connect_addr.sin_port = htons(SOCK_PORT_1);
>> + connect_addr.sin_addr.s_addr = htonl(INADDR_ANY);
>> + memset(&(connect_addr.sin_zero), '\0', 8);
>> +
>> + /* Make connection to the listening socket 1 */
>> + ASSERT_EQ(0, connect(child_sockfd, (struct sockaddr
>> *)&connect_addr,
>> + sizeof(struct sockaddr)));
>> + _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
>> + return;
>> + }
>> + /* Accept connection from the child 1 */
>> + new_fd = accept(sockfd_1, NULL, 0);
>> + ASSERT_LE(0, new_fd);
>> +
>> + /* Close connection */
>> + ASSERT_EQ(0, close(new_fd));
>> +
>> + ASSERT_EQ(child_1, waitpid(child_1, &status, 0));
>> + ASSERT_EQ(1, WIFEXITED(status));
>> + ASSERT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));
>> +
>> + /* Create a server socket 2 */
>> + sockfd_2 = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, sockfd_2);
>> + /* Allow reuse of local addresses */
>> + ASSERT_EQ(0, setsockopt(sockfd_2, SOL_SOCKET, SO_REUSEADDR, &one,
>> sizeof(one)));
>> +
>> + /* Set socket 2 address parameters */
>> + addr_2.sin_family = AF_INET;
>> + addr_2.sin_port = htons(SOCK_PORT_2);
>> + addr_2.sin_addr.s_addr = inet_addr(IP_ADDRESS);
>> + memset(&(addr_2.sin_zero), '\0', 8);
>> +
>> + /* Bind the socket 2 to IP address */
>> + ASSERT_EQ(0, bind(sockfd_2, (struct sockaddr *)&addr_2,
>> sizeof(addr_2)));
>> +
>> + /* Make listening socket 2 */
>> + ASSERT_EQ(0, listen(sockfd_2, BACKLOG));
>> +
>> + child_2 = fork();
>> + ASSERT_LE(0, child_2);
>> + if (child_2 == 0) {
>> + int child_sockfd;
>> + struct sockaddr_in connect_addr;
>> +
>> + /* Close listening socket for the child */
>> + ASSERT_EQ(0, close(sockfd_2));
>> + /* Create a stream client socket */
>> + child_sockfd = socket(AF_INET, SOCK_STREAM, 0);
>> + ASSERT_LE(0, child_sockfd);
>> +
>> + /* Set server's socket address parameters*/
>> + connect_addr.sin_family = AF_INET;
>> + connect_addr.sin_port = htons(SOCK_PORT_2);
>> + connect_addr.sin_addr.s_addr = htonl(INADDR_ANY);
>> + memset(&(connect_addr.sin_zero), '\0', 8);
>> +
>> + /* Make connection to the listening socket */
>> + ASSERT_EQ(-1, connect(child_sockfd, (struct sockaddr
>> *)&connect_addr,
>> + sizeof(struct sockaddr)));
>> + ASSERT_EQ(EACCES, errno);
>> + _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
>> + return;
>> + }
>> +
>> + ASSERT_EQ(child_2, waitpid(child_2, &status, 0));
>> + ASSERT_EQ(1, WIFEXITED(status));
>> + ASSERT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));
>> +}
>> +
>> +TEST_HARNESS_MAIN
> .
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