Rust-for-Linux
diff --git a/Diff for: ‎include/linux/lsm_hooks.h
+43-9 b/Diff for: ‎include/linux/lsm_hooks.h
+43-9
@@ -30,19 +30,47 @@
 #include <linux/init.h>
 #include <linux/rculist.h>
 #include <linux/xattr.h>
+#include <linux/static_call.h>
+#include <linux/unroll.h>
+#include <linux/jump_label.h>
+#include <linux/lsm_count.h>
 
 union security_list_options {
 	#define LSM_HOOK(RET, DEFAULT, NAME, ...) RET (*NAME)(__VA_ARGS__);
 	#include "lsm_hook_defs.h"
 	#undef LSM_HOOK
+	void *lsm_func_addr;
 };
 
-struct security_hook_heads {
-	#define LSM_HOOK(RET, DEFAULT, NAME, ...) struct hlist_head NAME;
-	#include "lsm_hook_defs.h"
-	#undef LSM_HOOK
+/*
+ * @key: static call key as defined by STATIC_CALL_KEY
+ * @trampoline: static call trampoline as defined by STATIC_CALL_TRAMP
+ * @hl: The security_hook_list as initialized by the owning LSM.
+ * @active: Enabled when the static call has an LSM hook associated.
+ */
+struct lsm_static_call {
+	struct static_call_key *key;
+	void *trampoline;
+	struct security_hook_list *hl;
+	/* this needs to be true or false based on what the key defaults to */
+	struct static_key_false *active;
 } __randomize_layout;
 
+/*
+ * Table of the static calls for each LSM hook.
+ * Once the LSMs are initialized, their callbacks will be copied to these
+ * tables such that the calls are filled backwards (from last to first).
+ * This way, we can jump directly to the first used static call, and execute
+ * all of them after. This essentially makes the entry point
+ * dynamic to adapt the number of static calls to the number of callbacks.
+ */
+struct lsm_static_calls_table {
+	#define LSM_HOOK(RET, DEFAULT, NAME, ...) \
+		struct lsm_static_call NAME[MAX_LSM_COUNT];
+	#include <linux/lsm_hook_defs.h>
+	#undef LSM_HOOK
+} __packed __randomize_layout;
+
 /**
  * struct lsm_id - Identify a Linux Security Module.
  * @lsm: name of the LSM, must be approved by the LSM maintainers
@@ -58,10 +86,14 @@ struct lsm_id {
 /*
  * Security module hook list structure.
  * For use with generic list macros for common operations.
+ *
+ * struct security_hook_list - Contents of a cacheable, mappable object.
+ * @scalls: The beginning of the array of static calls assigned to this hook.
+ * @hook: The callback for the hook.
+ * @lsm: The name of the lsm that owns this hook.
  */
 struct security_hook_list {
-	struct hlist_node list;
-	struct hlist_head *head;
+	struct lsm_static_call *scalls;
 	union security_list_options hook;
 	const struct lsm_id *lsmid;
 } __randomize_layout;
@@ -98,8 +130,11 @@ struct lsm_blob_sizes {
  * care of the common case and reduces the amount of
  * text involved.
  */
-#define LSM_HOOK_INIT(HEAD, HOOK) \
-	{ .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } }
+#define LSM_HOOK_INIT(NAME, HOOK)			\
+	{						\
+		.scalls = static_calls_table.NAME,	\
+		.hook = { .NAME = HOOK }		\
+	}
 
 extern void security_add_hooks(struct security_hook_list *hooks, int count,
 			       const struct lsm_id *lsmid);
@@ -134,7 +169,6 @@ struct lsm_info {
 
 /* DO NOT tamper with these variables outside of the LSM framework */
 extern char *lsm_names;
-extern struct security_hook_heads security_hook_heads;
 extern struct lsm_static_calls_table static_calls_table __ro_after_init;
 extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
 extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[];