[PATCH v2 10/15] landlock: Expose the ruleset fd lookup to the rest of Landlock

[Justin Suess]

Rename get_ruleset_from_fd() to landlock_get_ruleset_from_fd() and
give it external linkage within Landlock, declared in ruleset.h next
to the other ruleset lifetime helpers.

A following commit implements the LSM kfunc policy hooks, which need
to translate a ruleset fd into a landlock_ruleset reference from
outside syscalls.c.  No behavioral change.

Cc: Mickaël Salaün <mic@xxxxxxxxxxx>
Signed-off-by: Justin Suess <utilityemal77@xxxxxxxxx>
---
 security/landlock/ruleset.h  | 3 +++
 security/landlock/syscalls.c | 9 +++++----
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index b536fa0425b7..b58e3d9846af 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -214,6 +214,9 @@ int landlock_store_rule(struct landlock_rules *const rules,
 
 void landlock_free_rules(struct landlock_rules *const rules);
 
+struct landlock_ruleset *landlock_get_ruleset_from_fd(const int fd,
+						      const fmode_t mode);
+
 /**
  * landlock_get_rule_root - Get the root of a rule tree by key type
  *
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 1d02d57f4c48..cb294a3582ae 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -305,8 +305,8 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
  * Returns an owned ruleset from a FD. It is thus needed to call
  * landlock_put_ruleset() on the return value.
  */
-static struct landlock_ruleset *get_ruleset_from_fd(const int fd,
-						    const fmode_t mode)
+struct landlock_ruleset *landlock_get_ruleset_from_fd(const int fd,
+						      const fmode_t mode)
 {
 	CLASS(fd, ruleset_f)(fd);
 	struct landlock_ruleset *ruleset;
@@ -486,7 +486,7 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
 		return -EINVAL;
 
 	/* Gets and checks the ruleset. */
-	ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_WRITE);
+	ruleset = landlock_get_ruleset_from_fd(ruleset_fd, FMODE_CAN_WRITE);
 	if (IS_ERR(ruleset))
 		return PTR_ERR(ruleset);
 
@@ -585,7 +585,8 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32,
 	      (flags & ~LANDLOCK_RESTRICT_SELF_TSYNC) ==
 		      LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF)) {
 		/* Gets and checks the ruleset. */
-		ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_READ);
+		ruleset = landlock_get_ruleset_from_fd(ruleset_fd,
+						       FMODE_CAN_READ);
 		if (IS_ERR(ruleset))
 			return PTR_ERR(ruleset);
 	}
-- 
2.55.0