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[173.164.112.133]) by smtp.gmail.com with ESMTPSA id u184-v6sm676442pgd.27.2018.09.24.17.18.46 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 24 Sep 2018 17:18:50 -0700 (PDT) From: Kees Cook To: James Morris Cc: Kees Cook , Casey Schaufler , John Johansen , Tetsuo Handa , Paul Moore , Stephen Smalley , "Schaufler, Casey" , LSM , Jonathan Corbet , linux-doc@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH security-next v3 21/29] LSM: Build ordered list of ordered LSMs for init Date: Mon, 24 Sep 2018 17:18:24 -0700 Message-Id: <20180925001832.18322-22-keescook@chromium.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180925001832.18322-1-keescook@chromium.org> References: <20180925001832.18322-1-keescook@chromium.org> Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org This constructs a list of ordered 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 --- security/security.c | 59 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 52 insertions(+), 7 deletions(-) diff --git a/security/security.c b/security/security.c index a98549b334af..ef1ced0a3a50 100644 --- a/security/security.c +++ b/security/security.c @@ -34,6 +34,9 @@ #define MAX_LSM_EVM_XATTR 2 +/* 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 @@ static __initdata const char *chosen_major_lsm; static __initconst const char * const builtin_lsm_enable = CONFIG_LSM_ENABLE; +/* Ordered list of LSMs to initialize. */ +static __initdata struct lsm_info **ordered_lsms; + static bool debug __initdata; #define init_debug(...) \ do { \ @@ -96,6 +102,45 @@ 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"); +} + +/* Populate ordered LSMs list from hard-coded list of LSMs. */ +static void __init prepare_lsm_order(void) +{ + struct lsm_info *lsm; + + for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { + if (strcmp(lsm->name, "integrity") == 0) + append_ordered_lsm(lsm, "builtin"); + } +} + /* Is an LSM allowed to be initialized? */ static bool __init lsm_allowed(struct lsm_info *lsm) { @@ -126,14 +171,10 @@ static void __init maybe_initialize_lsm(struct lsm_info *lsm) static void __init ordered_lsm_init(void) { - struct lsm_info *lsm; - - for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) { - if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) != 0) - continue; + struct lsm_info **lsm; - maybe_initialize_lsm(lsm); - } + for (lsm = ordered_lsms; *lsm; lsm++) + maybe_initialize_lsm(*lsm); } static void __init major_lsm_init(void) @@ -215,6 +256,8 @@ int __init security_init(void) for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head); i++) INIT_HLIST_HEAD(&list[i]); + ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms), + GFP_KERNEL); /* Figure out which LSMs are enabled and disabled. */ prepare_lsm_enable(); @@ -227,6 +270,7 @@ int __init security_init(void) loadpin_add_hooks(); /* Load LSMs in specified order. */ + prepare_lsm_order(); ordered_lsm_init(); /* @@ -234,6 +278,7 @@ int __init security_init(void) */ major_lsm_init(); + kfree(ordered_lsms); return 0; } -- 2.17.1