linux-hardening - [PATCH 8/9] integrity: Move trivial hooks into LSM

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Date:   Thu, 13 Oct 2022 15:36:53 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Mimi Zohar <zohar@...ux.ibm.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        Paul Moore <paul@...l-moore.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Mickaël Salaün <mic@...ikod.net>,
        KP Singh <kpsingh@...nel.org>,
        Casey Schaufler <casey@...aufler-ca.com>,
        John Johansen <john.johansen@...onical.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH 8/9] integrity: Move trivial hooks into LSM

Move the integrity_inode_free and integrity_kernel_module_request hooks
into the LSM.

Cc: Mimi Zohar <zohar@...ux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Cc: Paul Moore <paul@...l-moore.com>
Cc: James Morris <jmorris@...ei.org>
Cc: "Serge E. Hallyn" <serge@...lyn.com>
Cc: linux-integrity@...r.kernel.org
Cc: linux-security-module@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 include/linux/integrity.h      | 19 -------------------
 security/integrity/iint.c      | 11 ++++++++++-
 security/integrity/integrity.h |  1 +
 security/security.c            |  8 +-------
 4 files changed, 12 insertions(+), 27 deletions(-)

diff --git a/include/linux/integrity.h b/include/linux/integrity.h
index 2ea0f2f65ab6..c86bcf6b866b 100644
--- a/include/linux/integrity.h
+++ b/include/linux/integrity.h
@@ -22,7 +22,6 @@ enum integrity_status {
 /* List of EVM protected security xattrs */
 #ifdef CONFIG_INTEGRITY
 extern struct integrity_iint_cache *integrity_inode_get(struct inode *inode);
-extern void integrity_inode_free(struct inode *inode);
 extern void __init integrity_load_keys(void);
 
 #else
@@ -32,27 +31,9 @@ static inline struct integrity_iint_cache *
 	return NULL;
 }
 
-static inline void integrity_inode_free(struct inode *inode)
-{
-	return;
-}
-
 static inline void integrity_load_keys(void)
 {
 }
 #endif /* CONFIG_INTEGRITY */
 
-#ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
-
-extern int integrity_kernel_module_request(char *kmod_name);
-
-#else
-
-static inline int integrity_kernel_module_request(char *kmod_name)
-{
-	return 0;
-}
-
-#endif /* CONFIG_INTEGRITY_ASYMMETRIC_KEYS */
-
 #endif /* _LINUX_INTEGRITY_H */
diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index 4f322324449d..dea4dbb93a53 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -142,7 +142,7 @@ struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
  *
  * Free the integrity information(iint) associated with an inode.
  */
-void integrity_inode_free(struct inode *inode)
+static void integrity_inode_free(struct inode *inode)
 {
 	struct integrity_iint_cache *iint;
 
@@ -177,12 +177,21 @@ void __init integrity_add_lsm_hooks(struct security_hook_list *hooks,
 	security_add_hooks(hooks, count, "integrity");
 }
 
+static struct security_hook_list integrity_hooks[] __lsm_ro_after_init = {
+	LSM_HOOK_INIT(inode_free_security, integrity_inode_free),
+#ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
+	LSM_HOOK_INIT(kernel_module_request, integrity_kernel_module_request),
+#endif
+};
+
 static int __init integrity_lsm_init(void)
 {
 	iint_cache =
 	    kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 			      0, SLAB_PANIC, init_once);
 
+	integrity_add_lsm_hooks(integrity_hooks, ARRAY_SIZE(integrity_hooks));
+
 	integrity_lsm_ima_init();
 	integrity_lsm_evm_init();
 
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 3707349271c9..93f35b208809 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -237,6 +237,7 @@ static inline int __init integrity_load_cert(const unsigned int id,
 #endif /* CONFIG_INTEGRITY_SIGNATURE */
 
 #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
+int integrity_kernel_module_request(char *kmod_name);
 int asymmetric_verify(struct key *keyring, const char *sig,
 		      int siglen, const char *data, int datalen);
 #else
diff --git a/security/security.c b/security/security.c
index af42264ad3e2..60c0ed336b23 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1036,7 +1036,6 @@ static void inode_free_by_rcu(struct rcu_head *head)
 
 void security_inode_free(struct inode *inode)
 {
-	integrity_inode_free(inode);
 	call_void_hook(inode_free_security, inode);
 	/*
 	 * The inode may still be referenced in a path walk and
@@ -1723,12 +1722,7 @@ int security_kernel_create_files_as(struct cred *new, struct inode *inode)
 
 int security_kernel_module_request(char *kmod_name)
 {
-	int ret;
-
-	ret = call_int_hook(kernel_module_request, 0, kmod_name);
-	if (ret)
-		return ret;
-	return integrity_kernel_module_request(kmod_name);
+	return call_int_hook(kernel_module_request, 0, kmod_name);
 }
 
 int security_kernel_read_file(struct file *file, enum kernel_read_file_id id,
-- 
2.34.1