landlock: Change landlock_add_rule(2) argument check ordering

commit 589172e5636c4d16c40b90e87543d43defe2d968 upstream.

This makes more sense to first check the ruleset FD and then the rule
attribute.  It will be useful to factor out code for other rule types.

Add inval_add_rule_arguments tests, extension of empty_path_beneath_attr
tests, to also check error ordering for landlock_add_rule(2).

Link: https://lore.kernel.org/r/20220506160820.524344-9-mic@digikod.net
Cc: stable@vger.kernel.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 7edc1d50e2bf2c1825f9f4195d3b7e6e3c97c989..a7396220c9d42c4b3df341235ab829c52790256b 100644 (file)
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -318,20 +318,24 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
        if (flags)
                return -EINVAL;
 
-       if (rule_type != LANDLOCK_RULE_PATH_BENEATH)
-               return -EINVAL;
-
-       /* Copies raw user space buffer, only one type for now. */
-       res = copy_from_user(&path_beneath_attr, rule_attr,
-                            sizeof(path_beneath_attr));
-       if (res)
-               return -EFAULT;
-
        /* Gets and checks the ruleset. */
        ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_WRITE);
        if (IS_ERR(ruleset))
                return PTR_ERR(ruleset);
 
+       if (rule_type != LANDLOCK_RULE_PATH_BENEATH) {
+               err = -EINVAL;
+               goto out_put_ruleset;
+       }
+
+       /* Copies raw user space buffer, only one type for now. */
+       res = copy_from_user(&path_beneath_attr, rule_attr,
+                            sizeof(path_beneath_attr));
+       if (res) {
+               err = -EFAULT;
+               goto out_put_ruleset;
+       }
+
        /*
         * Informs about useless rule: empty allowed_access (i.e. deny rules)
         * are ignored in path walks.

diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
index be9b937256acca71e7c4d80a5cf4dc3e05fad958..18b779471dcbe7928f3d5dd90b8142295c67a08e 100644 (file)
--- a/tools/testing/selftests/landlock/base_test.c
+++ b/tools/testing/selftests/landlock/base_test.c
@@ -121,20 +121,50 @@ TEST(inval_create_ruleset_flags)
        ASSERT_EQ(EINVAL, errno);
 }
 
-TEST(empty_path_beneath_attr)
+/* Tests ordering of syscall argument checks. */
+TEST(add_rule_checks_ordering)
 {
        const struct landlock_ruleset_attr ruleset_attr = {
                .handled_access_fs = LANDLOCK_ACCESS_FS_EXECUTE,
        };
+       struct landlock_path_beneath_attr path_beneath_attr = {
+               .allowed_access = LANDLOCK_ACCESS_FS_EXECUTE,
+               .parent_fd = -1,
+       };
        const int ruleset_fd =
                landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
 
        ASSERT_LE(0, ruleset_fd);
 
-       /* Similar to struct landlock_path_beneath_attr.parent_fd = 0 */
+       /* Checks invalid flags. */
+       ASSERT_EQ(-1, landlock_add_rule(-1, 0, NULL, 1));
+       ASSERT_EQ(EINVAL, errno);
+
+       /* Checks invalid ruleset FD. */
+       ASSERT_EQ(-1, landlock_add_rule(-1, 0, NULL, 0));
+       ASSERT_EQ(EBADF, errno);
+
+       /* Checks invalid rule type. */
+       ASSERT_EQ(-1, landlock_add_rule(ruleset_fd, 0, NULL, 0));
+       ASSERT_EQ(EINVAL, errno);
+
+       /* Checks invalid rule attr. */
        ASSERT_EQ(-1, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
                                        NULL, 0));
        ASSERT_EQ(EFAULT, errno);
+
+       /* Checks invalid path_beneath.parent_fd. */
+       ASSERT_EQ(-1, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
+                                       &path_beneath_attr, 0));
+       ASSERT_EQ(EBADF, errno);
+
+       /* Checks valid call. */
+       path_beneath_attr.parent_fd =
+               open("/tmp", O_PATH | O_NOFOLLOW | O_DIRECTORY | O_CLOEXEC);
+       ASSERT_LE(0, path_beneath_attr.parent_fd);
+       ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
+                                      &path_beneath_attr, 0));
+       ASSERT_EQ(0, close(path_beneath_attr.parent_fd));
        ASSERT_EQ(0, close(ruleset_fd));
 }