LSM: Infrastructure management of the ipc security blob

Move management of the kern_ipc_perm->security and
msg_msg->security blobs out of the individual security
modules and into the security infrastructure. Instead
of allocating the blobs from within the modules the modules
tell the infrastructure how much space is required, and
the space is allocated there.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
[kees: adjusted for ordered init series]
Signed-off-by: Kees Cook <keescook@chromium.org>

2 files changed, 6 insertions, 30 deletions

diff --git a/security/smack/smack.h b/security/smack/smack.h
index 0adddbeecc62..9c7c95a5c497 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -376,12 +376,12 @@ static inline struct inode_smack *smack_inode(const struct inode *inode)
 
 static inline struct smack_known **smack_msg_msg(const struct msg_msg *msg)
 {
-	return (struct smack_known **)&msg->security;
+	return msg->security + smack_blob_sizes.lbs_msg_msg;
 }
 
 static inline struct smack_known **smack_ipc(const struct kern_ipc_perm *ipc)
 {
-	return (struct smack_known **)&ipc->security;
+	return ipc->security + smack_blob_sizes.lbs_ipc;
 }
 
 /*
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 154521b6843b..0b848b1f6366 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2809,24 +2809,13 @@ static int smack_flags_to_may(int flags)
  */
 static int smack_msg_msg_alloc_security(struct msg_msg *msg)
 {
-	struct smack_known *skp = smk_of_current();
+	struct smack_known **blob = smack_msg_msg(msg);
 
-	msg->security = skp;
+	*blob = smk_of_current();
 	return 0;
 }
 
 /**
- * smack_msg_msg_free_security - Clear the security blob for msg_msg
- * @msg: the object
- *
- * Clears the blob pointer
- */
-static void smack_msg_msg_free_security(struct msg_msg *msg)
-{
-	msg->security = NULL;
-}
-
-/**
  * smack_of_ipc - the smack pointer for the ipc
  * @isp: the object
  *
@@ -2854,17 +2843,6 @@ static int smack_ipc_alloc_security(struct kern_ipc_perm *isp)
 }
 
 /**
- * smack_ipc_free_security - Clear the security blob for ipc
- * @isp: the object
- *
- * Clears the blob pointer
- */
-static void smack_ipc_free_security(struct kern_ipc_perm *isp)
-{
-	isp->security = NULL;
-}
-
-/**
  * smk_curacc_shm : check if current has access on shm
  * @isp : the object
  * @access : access requested
@@ -4511,6 +4489,8 @@ struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = {
 	.lbs_cred = sizeof(struct task_smack),
 	.lbs_file = sizeof(struct smack_known *),
 	.lbs_inode = sizeof(struct inode_smack),
+	.lbs_ipc = sizeof(struct smack_known *),
+	.lbs_msg_msg = sizeof(struct smack_known *),
 };
 
 static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
@@ -4581,23 +4561,19 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(ipc_getsecid, smack_ipc_getsecid),
 
 	LSM_HOOK_INIT(msg_msg_alloc_security, smack_msg_msg_alloc_security),
-	LSM_HOOK_INIT(msg_msg_free_security, smack_msg_msg_free_security),
 
 	LSM_HOOK_INIT(msg_queue_alloc_security, smack_ipc_alloc_security),
-	LSM_HOOK_INIT(msg_queue_free_security, smack_ipc_free_security),
 	LSM_HOOK_INIT(msg_queue_associate, smack_msg_queue_associate),
 	LSM_HOOK_INIT(msg_queue_msgctl, smack_msg_queue_msgctl),
 	LSM_HOOK_INIT(msg_queue_msgsnd, smack_msg_queue_msgsnd),
 	LSM_HOOK_INIT(msg_queue_msgrcv, smack_msg_queue_msgrcv),
 
 	LSM_HOOK_INIT(shm_alloc_security, smack_ipc_alloc_security),
-	LSM_HOOK_INIT(shm_free_security, smack_ipc_free_security),
 	LSM_HOOK_INIT(shm_associate, smack_shm_associate),
 	LSM_HOOK_INIT(shm_shmctl, smack_shm_shmctl),
 	LSM_HOOK_INIT(shm_shmat, smack_shm_shmat),
 
 	LSM_HOOK_INIT(sem_alloc_security, smack_ipc_alloc_security),
-	LSM_HOOK_INIT(sem_free_security, smack_ipc_free_security),
 	LSM_HOOK_INIT(sem_associate, smack_sem_associate),
 	LSM_HOOK_INIT(sem_semctl, smack_sem_semctl),
 	LSM_HOOK_INIT(sem_semop, smack_sem_semop),