On Fri, Jun 16, 2023 at 02:04:41AM +0200, KP Singh wrote:
> [...]
> @@ -110,6 +110,9 @@ static __initdata struct lsm_info *exclusive;
> #undef LSM_HOOK
> #undef DEFINE_LSM_STATIC_CALL
>
> +#define security_hook_active(n, h) \
> + static_branch_maybe(CONFIG_SECURITY_HOOK_LIKELY, &SECURITY_HOOK_ACTIVE_KEY(h, n))
> +
> /*
> * Initialise a table of static calls for each LSM hook.
> * DEFINE_STATIC_CALL_NULL invocation above generates a key (STATIC_CALL_KEY)
> @@ -816,7 +819,7 @@ static int lsm_superblock_alloc(struct super_block *sb)
> */
> #define __CALL_STATIC_VOID(NUM, HOOK, ...) \
> do { \
> - if (static_branch_unlikely(&SECURITY_HOOK_ACTIVE_KEY(HOOK, NUM))) { \
> + if (security_hook_active(NUM, HOOK)) { \
> static_call(LSM_STATIC_CALL(HOOK, NUM))(__VA_ARGS__); \
> } \
> } while (0);
> @@ -828,7 +831,7 @@ do { \
>
> #define __CALL_STATIC_INT(NUM, R, HOOK, LABEL, ...) \
> do { \
> - if (static_branch_unlikely(&SECURITY_HOOK_ACTIVE_KEY(HOOK, NUM))) { \
> + if (security_hook_active(NUM, HOOK)) { \
> R = static_call(LSM_STATIC_CALL(HOOK, NUM))(__VA_ARGS__); \
> if (R != 0) \
> goto LABEL; \
I actually think I'd prefer there be no macro wrapping
static_branch_maybe(), just for reading it more easily. i.e. people
reading this code are going to expect the static_branch/static_call code
patterns, and seeing "security_hook_active" only slows them down in
understanding it. I don't think it's _that_ ugly to have it all typed
out. e.g.:
if (static_branch_maybe(CONFIG_SECURITY_HOOK_LIKELY, \
&SECURITY_HOOK_ACTIVE_KEY(HOOK, NUM)) { \
R = static_call(LSM_STATIC_CALL(HOOK, NUM))(__VA_ARGS__); \
if (R != 0) \
goto LABEL; \
--
Kees Cook
