From 2d4d51198c730adbbc5e071b18c84e5d0d2d65df Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 19 Sep 2018 16:58:31 -0700 Subject: LSM: Build ordered list of LSMs to initialize This constructs an ordered list of LSMs to initialize, using a hard-coded list of only "integrity": minor LSMs continue to have direct hook calls, and major LSMs continue to initialize separately. Signed-off-by: Kees Cook Reviewed-by: Casey Schaufler --- security/security.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 53 insertions(+), 5 deletions(-) diff --git a/security/security.c b/security/security.c index c900d7a1441a..3a277fbf6023 100644 --- a/security/security.c +++ b/security/security.c @@ -37,6 +37,9 @@ /* Maximum number of letters for an LSM name string */ #define SECURITY_NAME_MAX 10 +/* How many LSMs were built into the kernel? */ +#define LSM_COUNT (__end_lsm_info - __start_lsm_info) + struct security_hook_heads security_hook_heads __lsm_ro_after_init; static ATOMIC_NOTIFIER_HEAD(lsm_notifier_chain); @@ -45,6 +48,9 @@ char *lsm_names; static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] = CONFIG_DEFAULT_SECURITY; +/* Ordered list of LSMs to initialize. */ +static __initdata struct lsm_info **ordered_lsms; + static __initdata bool debug; #define init_debug(...) \ do { \ @@ -85,6 +91,34 @@ static void __init set_enabled(struct lsm_info *lsm, bool enabled) } } +/* Is an LSM already listed in the ordered LSMs list? */ +static bool __init exists_ordered_lsm(struct lsm_info *lsm) +{ + struct lsm_info **check; + + for (check = ordered_lsms; *check; check++) + if (*check == lsm) + return true; + + return false; +} + +/* Append an LSM to the list of ordered LSMs to initialize. */ +static int last_lsm __initdata; +static void __init append_ordered_lsm(struct lsm_info *lsm, const char *from) +{ + /* Ignore duplicate selections. */ + if (exists_ordered_lsm(lsm)) + return; + + if (WARN(last_lsm == LSM_COUNT, "%s: out of LSM slots!?\n", from)) + return; + + ordered_lsms[last_lsm++] = lsm; + init_debug("%s ordering: %s (%sabled)\n", from, lsm->name, + is_enabled(lsm) ? "en" : "dis"); +} + /* Is an LSM allowed to be initialized? */ static bool __init lsm_allowed(struct lsm_info *lsm) { @@ -121,18 +155,32 @@ static void __init maybe_initialize_lsm(struct lsm_info *lsm) } } -static void __init ordered_lsm_init(void) +/* Populate ordered LSMs list from single LSM name. */ +static void __init ordered_lsm_parse(const char *order, const char *origin) { struct lsm_info *lsm; for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { - if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) != 0) - continue; - - maybe_initialize_lsm(lsm); + if (strcmp(lsm->name, order) == 0) + append_ordered_lsm(lsm, origin); } } +static void __init ordered_lsm_init(void) +{ + struct lsm_info **lsm; + + ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms), + GFP_KERNEL); + + ordered_lsm_parse("integrity", "builtin"); + + for (lsm = ordered_lsms; *lsm; lsm++) + maybe_initialize_lsm(*lsm); + + kfree(ordered_lsms); +} + static void __init major_lsm_init(void) { struct lsm_info *lsm; -- cgit v1.2.3