Unverified Commit cc374782 authored by Mickaël Salaün's avatar Mickaël Salaün
Browse files

selftests/landlock: Add cred_transfer test 



Check that keyctl(KEYCTL_SESSION_TO_PARENT) preserves the parent's
restrictions.

Fixes: e1199815 ("selftests/landlock: Add user space tests")
Co-developed-by: default avatarJann Horn <jannh@google.com>
Signed-off-by: default avatarJann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20240724.Ood5aige9she@digikod.net


Signed-off-by: default avatarMickaël Salaün <mic@digikod.net>
parent 39705a6c

tools/testing/selftests/landlock/base_test.c

+74 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#define _GNU_SOURCE

#include <errno.h>

#include <fcntl.h>

#include <linux/keyctl.h>

#include <linux/landlock.h>

#include <string.h>

#include <sys/prctl.h>
@@ -326,4 +327,77 @@ TEST(ruleset_fd_transfer) 
	ASSERT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));

}



TEST(cred_transfer)

{

	struct landlock_ruleset_attr ruleset_attr = {

		.handled_access_fs = LANDLOCK_ACCESS_FS_READ_DIR,

	};

	int ruleset_fd, dir_fd;

	pid_t child;

	int status;



	drop_caps(_metadata);



	dir_fd = open("/", O_RDONLY | O_DIRECTORY | O_CLOEXEC);

	EXPECT_LE(0, dir_fd);

	EXPECT_EQ(0, close(dir_fd));



	/* Denies opening directories. */

	ruleset_fd =

		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);

	ASSERT_LE(0, ruleset_fd);

	EXPECT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));

	ASSERT_EQ(0, landlock_restrict_self(ruleset_fd, 0));

	EXPECT_EQ(0, close(ruleset_fd));



	/* Checks ruleset enforcement. */

	EXPECT_EQ(-1, open("/", O_RDONLY | O_DIRECTORY | O_CLOEXEC));

	EXPECT_EQ(EACCES, errno);



	/* Needed for KEYCTL_SESSION_TO_PARENT permission checks */

	EXPECT_NE(-1, syscall(__NR_keyctl, KEYCTL_JOIN_SESSION_KEYRING, NULL, 0,

			      0, 0))

	{

		TH_LOG("Failed to join session keyring: %s", strerror(errno));

	}



	child = fork();

	ASSERT_LE(0, child);

	if (child == 0) {

		/* Checks ruleset enforcement. */

		EXPECT_EQ(-1, open("/", O_RDONLY | O_DIRECTORY | O_CLOEXEC));

		EXPECT_EQ(EACCES, errno);



		/*

		 * KEYCTL_SESSION_TO_PARENT is a no-op unless we have a

		 * different session keyring in the child, so make that happen.

		 */

		EXPECT_NE(-1, syscall(__NR_keyctl, KEYCTL_JOIN_SESSION_KEYRING,

				      NULL, 0, 0, 0));



		/*

		 * KEYCTL_SESSION_TO_PARENT installs credentials on the parent

		 * that never go through the cred_prepare hook, this path uses

		 * cred_transfer instead.

		 */

		EXPECT_EQ(0, syscall(__NR_keyctl, KEYCTL_SESSION_TO_PARENT, 0,

				     0, 0, 0));



		/* Re-checks ruleset enforcement. */

		EXPECT_EQ(-1, open("/", O_RDONLY | O_DIRECTORY | O_CLOEXEC));

		EXPECT_EQ(EACCES, errno);



		_exit(_metadata->exit_code);

		return;

	}



	EXPECT_EQ(child, waitpid(child, &status, 0));

	EXPECT_EQ(1, WIFEXITED(status));

	EXPECT_EQ(EXIT_SUCCESS, WEXITSTATUS(status));



	/* Re-checks ruleset enforcement. */

	EXPECT_EQ(-1, open("/", O_RDONLY | O_DIRECTORY | O_CLOEXEC));

	EXPECT_EQ(EACCES, errno);

}



TEST_HARNESS_MAIN

tools/testing/selftests/landlock/config

+1 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ CONFIG_CGROUPS=y 
CONFIG_CGROUP_SCHED=y

CONFIG_INET=y

CONFIG_IPV6=y

CONFIG_KEYS=y

CONFIG_NET=y

CONFIG_NET_NS=y

CONFIG_OVERLAY_FS=y