Commit 75c1182e authored by Bill Wendling's avatar Bill Wendling Committed by Kees Cook
Browse files

security: don't treat structure as an array of struct hlist_head 



The initialization of "security_hook_heads" is done by casting it to
another structure pointer type, and treating it as an array of "struct
hlist_head" objects. This requires an exception be made in "randstruct",
because otherwise it will emit an error, reducing the effectiveness of
the hardening technique.

Instead of using a cast, initialize the individual struct hlist_head
elements in security_hook_heads explicitly. This removes the need for
the cast and randstruct exception.

Signed-off-by: default avatarBill Wendling <morbo@google.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220407175930.471870-1-morbo@google.com
parent 1109a5d9

scripts/gcc-plugins/randomize_layout_plugin.c

+0 −2
Original line number Diff line number Diff line
@@ -52,8 +52,6 @@ static const struct whitelist_entry whitelist[] = { 
	{ "net/unix/af_unix.c", "unix_skb_parms", "char" },

	/* big_key payload.data struct splashing */

	{ "security/keys/big_key.c", "path", "void *" },

	/* walk struct security_hook_heads as an array of struct hlist_head */

	{ "security/security.c", "hlist_head", "security_hook_heads" },

	{ }

};

security/security.c

+4 −5
Original line number Diff line number Diff line
@@ -365,13 +365,12 @@ static void __init ordered_lsm_init(void) 


int __init early_security_init(void)

{

	int i;

	struct hlist_head *list = (struct hlist_head *) &security_hook_heads;

	struct lsm_info *lsm;



	for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);

	     i++)

		INIT_HLIST_HEAD(&list[i]);

#define LSM_HOOK(RET, DEFAULT, NAME, ...) \

	INIT_HLIST_HEAD(&security_hook_heads.NAME);

#include "linux/lsm_hook_defs.h"

#undef LSM_HOOK



	for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {

		if (!lsm->enabled)