5.15-stable review patch. If anyone has any objections, please let me know.
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From: Mickaël Salaün mic@digikod.net
commit cc374782b6ca0fd634482391da977542443d3368 upstream.
Check that keyctl(KEYCTL_SESSION_TO_PARENT) preserves the parent's restrictions.
Fixes: e1199815b47b ("selftests/landlock: Add user space tests") Co-developed-by: Jann Horn jannh@google.com Signed-off-by: Jann Horn jannh@google.com Link: https://lore.kernel.org/r/20240724.Ood5aige9she@digikod.net Signed-off-by: Mickaël Salaün mic@digikod.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/testing/selftests/landlock/base_test.c | 74 +++++++++++++++++++++++++++ tools/testing/selftests/landlock/config | 5 + 2 files changed, 77 insertions(+), 2 deletions(-)
--- a/tools/testing/selftests/landlock/base_test.c +++ b/tools/testing/selftests/landlock/base_test.c @@ -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> @@ -356,4 +357,77 @@ 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->passed ? EXIT_SUCCESS : EXIT_FAILURE); + 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 --- a/tools/testing/selftests/landlock/config +++ b/tools/testing/selftests/landlock/config @@ -1,7 +1,8 @@ +CONFIG_KEYS=y CONFIG_OVERLAY_FS=y +CONFIG_SECURITY=y CONFIG_SECURITY_LANDLOCK=y CONFIG_SECURITY_PATH=y -CONFIG_SECURITY=y CONFIG_SHMEM=y -CONFIG_TMPFS_XATTR=y CONFIG_TMPFS=y +CONFIG_TMPFS_XATTR=y