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landlock: Change landlock_add_rule(2) argument check ordering 

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>
This commit is contained in:
Mickaël Salaün 2022-05-06 18:08:18 +02:00
parent d1788ad990
commit 589172e563
No known key found for this signature in database
GPG Key ID: E5E3D0E88C82F6D2
2 changed files with 45 additions and 11 deletions
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22
security/landlock/syscalls.c
View File

@ -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.

34
tools/testing/selftests/landlock/base_test.c
View File

@ -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));
}