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>

6 files changed, 110 insertions, 121 deletions

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 9b39fefa88c4..40511a8a5ae6 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -2034,6 +2034,8 @@ struct lsm_blob_sizes {
 	int	lbs_cred;
 	int	lbs_file;
 	int	lbs_inode;
+	int	lbs_ipc;
+	int	lbs_msg_msg;
 	int	lbs_task;
 };
 
diff --git a/security/security.c b/security/security.c
index e59a1e1514ee..953fc3ea18a9 100644
--- a/security/security.c
+++ b/security/security.c
@@ -30,6 +30,7 @@
 #include <linux/personality.h>
 #include <linux/backing-dev.h>
 #include <linux/string.h>
+#include <linux/msg.h>
 #include <net/flow.h>
 
 #define MAX_LSM_EVM_XATTR	2
@@ -169,6 +170,8 @@ static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed)
 	if (needed->lbs_inode && blob_sizes.lbs_inode == 0)
 		blob_sizes.lbs_inode = sizeof(struct rcu_head);
 	lsm_set_blob_size(&needed->lbs_inode, &blob_sizes.lbs_inode);
+	lsm_set_blob_size(&needed->lbs_ipc, &blob_sizes.lbs_ipc);
+	lsm_set_blob_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
 	lsm_set_blob_size(&needed->lbs_task, &blob_sizes.lbs_task);
 }
 
@@ -293,6 +296,8 @@ static void __init ordered_lsm_init(void)
 	init_debug("cred blob size     = %d\n", blob_sizes.lbs_cred);
 	init_debug("file blob size     = %d\n", blob_sizes.lbs_file);
 	init_debug("inode blob size    = %d\n", blob_sizes.lbs_inode);
+	init_debug("ipc blob size      = %d\n", blob_sizes.lbs_ipc);
+	init_debug("msg_msg blob size  = %d\n", blob_sizes.lbs_msg_msg);
 	init_debug("task blob size     = %d\n", blob_sizes.lbs_task);
 
 	/*
@@ -539,6 +544,48 @@ int lsm_task_alloc(struct task_struct *task)
 }
 
 /**
+ * lsm_ipc_alloc - allocate a composite ipc blob
+ * @kip: the ipc that needs a blob
+ *
+ * Allocate the ipc blob for all the modules
+ *
+ * Returns 0, or -ENOMEM if memory can't be allocated.
+ */
+int lsm_ipc_alloc(struct kern_ipc_perm *kip)
+{
+	if (blob_sizes.lbs_ipc == 0) {
+		kip->security = NULL;
+		return 0;
+	}
+
+	kip->security = kzalloc(blob_sizes.lbs_ipc, GFP_KERNEL);
+	if (kip->security == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
+ * lsm_msg_msg_alloc - allocate a composite msg_msg blob
+ * @mp: the msg_msg that needs a blob
+ *
+ * Allocate the ipc blob for all the modules
+ *
+ * Returns 0, or -ENOMEM if memory can't be allocated.
+ */
+int lsm_msg_msg_alloc(struct msg_msg *mp)
+{
+	if (blob_sizes.lbs_msg_msg == 0) {
+		mp->security = NULL;
+		return 0;
+	}
+
+	mp->security = kzalloc(blob_sizes.lbs_msg_msg, GFP_KERNEL);
+	if (mp->security == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
  * lsm_early_task - during initialization allocate a composite task blob
  * @task: the task that needs a blob
  *
@@ -1631,22 +1678,40 @@ void security_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid)
 
 int security_msg_msg_alloc(struct msg_msg *msg)
 {
-	return call_int_hook(msg_msg_alloc_security, 0, msg);
+	int rc = lsm_msg_msg_alloc(msg);
+
+	if (unlikely(rc))
+		return rc;
+	rc = call_int_hook(msg_msg_alloc_security, 0, msg);
+	if (unlikely(rc))
+		security_msg_msg_free(msg);
+	return rc;
 }
 
 void security_msg_msg_free(struct msg_msg *msg)
 {
 	call_void_hook(msg_msg_free_security, msg);
+	kfree(msg->security);
+	msg->security = NULL;
 }
 
 int security_msg_queue_alloc(struct kern_ipc_perm *msq)
 {
-	return call_int_hook(msg_queue_alloc_security, 0, msq);
+	int rc = lsm_ipc_alloc(msq);
+
+	if (unlikely(rc))
+		return rc;
+	rc = call_int_hook(msg_queue_alloc_security, 0, msq);
+	if (unlikely(rc))
+		security_msg_queue_free(msq);
+	return rc;
 }
 
 void security_msg_queue_free(struct kern_ipc_perm *msq)
 {
 	call_void_hook(msg_queue_free_security, msq);
+	kfree(msq->security);
+	msq->security = NULL;
 }
 
 int security_msg_queue_associate(struct kern_ipc_perm *msq, int msqflg)
@@ -1673,12 +1738,21 @@ int security_msg_queue_msgrcv(struct kern_ipc_perm *msq, struct msg_msg *msg,
 
 int security_shm_alloc(struct kern_ipc_perm *shp)
 {
-	return call_int_hook(shm_alloc_security, 0, shp);
+	int rc = lsm_ipc_alloc(shp);
+
+	if (unlikely(rc))
+		return rc;
+	rc = call_int_hook(shm_alloc_security, 0, shp);
+	if (unlikely(rc))
+		security_shm_free(shp);
+	return rc;
 }
 
 void security_shm_free(struct kern_ipc_perm *shp)
 {
 	call_void_hook(shm_free_security, shp);
+	kfree(shp->security);
+	shp->security = NULL;
 }
 
 int security_shm_associate(struct kern_ipc_perm *shp, int shmflg)
@@ -1698,12 +1772,21 @@ int security_shm_shmat(struct kern_ipc_perm *shp, char __user *shmaddr, int shmf
 
 int security_sem_alloc(struct kern_ipc_perm *sma)
 {
-	return call_int_hook(sem_alloc_security, 0, sma);
+	int rc = lsm_ipc_alloc(sma);
+
+	if (unlikely(rc))
+		return rc;
+	rc = call_int_hook(sem_alloc_security, 0, sma);
+	if (unlikely(rc))
+		security_sem_free(sma);
+	return rc;
 }
 
 void security_sem_free(struct kern_ipc_perm *sma)
 {
 	call_void_hook(sem_free_security, sma);
+	kfree(sma->security);
+	sma->security = NULL;
 }
 
 int security_sem_associate(struct kern_ipc_perm *sma, int semflg)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 4b64ad31326f..d98e1d8d18f6 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5626,51 +5626,22 @@ static int selinux_netlink_send(struct sock *sk, struct sk_buff *skb)
 	return selinux_nlmsg_perm(sk, skb);
 }
 
-static int ipc_alloc_security(struct kern_ipc_perm *perm,
-			      u16 sclass)
+static void ipc_init_security(struct ipc_security_struct *isec, u16 sclass)
 {
-	struct ipc_security_struct *isec;
-
-	isec = kzalloc(sizeof(struct ipc_security_struct), GFP_KERNEL);
-	if (!isec)
-		return -ENOMEM;
-
 	isec->sclass = sclass;
 	isec->sid = current_sid();
-	perm->security = isec;
-
-	return 0;
-}
-
-static void ipc_free_security(struct kern_ipc_perm *perm)
-{
-	struct ipc_security_struct *isec = perm->security;
-	perm->security = NULL;
-	kfree(isec);
 }
 
 static int msg_msg_alloc_security(struct msg_msg *msg)
 {
 	struct msg_security_struct *msec;
 
-	msec = kzalloc(sizeof(struct msg_security_struct), GFP_KERNEL);
-	if (!msec)
-		return -ENOMEM;
-
+	msec = selinux_msg_msg(msg);
 	msec->sid = SECINITSID_UNLABELED;
-	msg->security = msec;
 
 	return 0;
 }
 
-static void msg_msg_free_security(struct msg_msg *msg)
-{
-	struct msg_security_struct *msec = msg->security;
-
-	msg->security = NULL;
-	kfree(msec);
-}
-
 static int ipc_has_perm(struct kern_ipc_perm *ipc_perms,
 			u32 perms)
 {
@@ -5692,11 +5663,6 @@ static int selinux_msg_msg_alloc_security(struct msg_msg *msg)
 	return msg_msg_alloc_security(msg);
 }
 
-static void selinux_msg_msg_free_security(struct msg_msg *msg)
-{
-	msg_msg_free_security(msg);
-}
-
 /* message queue security operations */
 static int selinux_msg_queue_alloc_security(struct kern_ipc_perm *msq)
 {
@@ -5705,11 +5671,8 @@ static int selinux_msg_queue_alloc_security(struct kern_ipc_perm *msq)
 	u32 sid = current_sid();
 	int rc;
 
-	rc = ipc_alloc_security(msq, SECCLASS_MSGQ);
-	if (rc)
-		return rc;
-
-	isec = msq->security;
+	isec = selinux_ipc(msq);
+	ipc_init_security(isec, SECCLASS_MSGQ);
 
 	ad.type = LSM_AUDIT_DATA_IPC;
 	ad.u.ipc_id = msq->key;
@@ -5717,16 +5680,7 @@ static int selinux_msg_queue_alloc_security(struct kern_ipc_perm *msq)
 	rc = avc_has_perm(&selinux_state,
 			  sid, isec->sid, SECCLASS_MSGQ,
 			  MSGQ__CREATE, &ad);
-	if (rc) {
-		ipc_free_security(msq);
-		return rc;
-	}
-	return 0;
-}
-
-static void selinux_msg_queue_free_security(struct kern_ipc_perm *msq)
-{
-	ipc_free_security(msq);
+	return rc;
 }
 
 static int selinux_msg_queue_associate(struct kern_ipc_perm *msq, int msqflg)
@@ -5856,11 +5810,8 @@ static int selinux_shm_alloc_security(struct kern_ipc_perm *shp)
 	u32 sid = current_sid();
 	int rc;
 
-	rc = ipc_alloc_security(shp, SECCLASS_SHM);
-	if (rc)
-		return rc;
-
-	isec = shp->security;
+	isec = selinux_ipc(shp);
+	ipc_init_security(isec, SECCLASS_SHM);
 
 	ad.type = LSM_AUDIT_DATA_IPC;
 	ad.u.ipc_id = shp->key;
@@ -5868,16 +5819,7 @@ static int selinux_shm_alloc_security(struct kern_ipc_perm *shp)
 	rc = avc_has_perm(&selinux_state,
 			  sid, isec->sid, SECCLASS_SHM,
 			  SHM__CREATE, &ad);
-	if (rc) {
-		ipc_free_security(shp);
-		return rc;
-	}
-	return 0;
-}
-
-static void selinux_shm_free_security(struct kern_ipc_perm *shp)
-{
-	ipc_free_security(shp);
+	return rc;
 }
 
 static int selinux_shm_associate(struct kern_ipc_perm *shp, int shmflg)
@@ -5953,11 +5895,8 @@ static int selinux_sem_alloc_security(struct kern_ipc_perm *sma)
 	u32 sid = current_sid();
 	int rc;
 
-	rc = ipc_alloc_security(sma, SECCLASS_SEM);
-	if (rc)
-		return rc;
-
-	isec = sma->security;
+	isec = selinux_ipc(sma);
+	ipc_init_security(isec, SECCLASS_SEM);
 
 	ad.type = LSM_AUDIT_DATA_IPC;
 	ad.u.ipc_id = sma->key;
@@ -5965,16 +5904,7 @@ static int selinux_sem_alloc_security(struct kern_ipc_perm *sma)
 	rc = avc_has_perm(&selinux_state,
 			  sid, isec->sid, SECCLASS_SEM,
 			  SEM__CREATE, &ad);
-	if (rc) {
-		ipc_free_security(sma);
-		return rc;
-	}
-	return 0;
-}
-
-static void selinux_sem_free_security(struct kern_ipc_perm *sma)
-{
-	ipc_free_security(sma);
+	return rc;
 }
 
 static int selinux_sem_associate(struct kern_ipc_perm *sma, int semflg)
@@ -6607,6 +6537,8 @@ struct lsm_blob_sizes selinux_blob_sizes __lsm_ro_after_init = {
 	.lbs_cred = sizeof(struct task_security_struct),
 	.lbs_file = sizeof(struct file_security_struct),
 	.lbs_inode = sizeof(struct inode_security_struct),
+	.lbs_ipc = sizeof(struct ipc_security_struct),
+	.lbs_msg_msg = sizeof(struct msg_security_struct),
 };
 
 static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
@@ -6718,24 +6650,20 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(ipc_getsecid, selinux_ipc_getsecid),
 
 	LSM_HOOK_INIT(msg_msg_alloc_security, selinux_msg_msg_alloc_security),
-	LSM_HOOK_INIT(msg_msg_free_security, selinux_msg_msg_free_security),
 
 	LSM_HOOK_INIT(msg_queue_alloc_security,
 			selinux_msg_queue_alloc_security),
-	LSM_HOOK_INIT(msg_queue_free_security, selinux_msg_queue_free_security),
 	LSM_HOOK_INIT(msg_queue_associate, selinux_msg_queue_associate),
 	LSM_HOOK_INIT(msg_queue_msgctl, selinux_msg_queue_msgctl),
 	LSM_HOOK_INIT(msg_queue_msgsnd, selinux_msg_queue_msgsnd),
 	LSM_HOOK_INIT(msg_queue_msgrcv, selinux_msg_queue_msgrcv),
 
 	LSM_HOOK_INIT(shm_alloc_security, selinux_shm_alloc_security),
-	LSM_HOOK_INIT(shm_free_security, selinux_shm_free_security),
 	LSM_HOOK_INIT(shm_associate, selinux_shm_associate),
 	LSM_HOOK_INIT(shm_shmctl, selinux_shm_shmctl),
 	LSM_HOOK_INIT(shm_shmat, selinux_shm_shmat),
 
 	LSM_HOOK_INIT(sem_alloc_security, selinux_sem_alloc_security),
-	LSM_HOOK_INIT(sem_free_security, selinux_sem_free_security),
 	LSM_HOOK_INIT(sem_associate, selinux_sem_associate),
 	LSM_HOOK_INIT(sem_semctl, selinux_sem_semctl),
 	LSM_HOOK_INIT(sem_semop, selinux_sem_semop),
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index 539cacf4a572..231262d8eac9 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -179,13 +179,13 @@ static inline struct inode_security_struct *selinux_inode(
 static inline struct msg_security_struct *selinux_msg_msg(
 						const struct msg_msg *msg_msg)
 {
-	return msg_msg->security;
+	return msg_msg->security + selinux_blob_sizes.lbs_msg_msg;
 }
 
 static inline struct ipc_security_struct *selinux_ipc(
 						const struct kern_ipc_perm *ipc)
 {
-	return ipc->security;
+	return ipc->security + selinux_blob_sizes.lbs_ipc;
 }
 
 #endif /* _SELINUX_OBJSEC_H_ */
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),