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 <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
[kees: adjusted for ordered init series]
Signed-off-by: Kees Cook <[e-mail]>

include/linux/lsm_hooks.h

···
 	int	lbs_cred;
 	int	lbs_file;
 	int	lbs_inode;
+	int	lbs_ipc;
+	int	lbs_msg_msg;
 	int	lbs_task;
 };
 

security/security.c

···
 #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
···
 	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);
 }
 
···
 	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);
 
 	/*
···
 
 	task->security = kzalloc(blob_sizes.lbs_task, GFP_KERNEL);
 	if (task->security == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
+ * 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;
 }
···
 
 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)
···
 
 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)
···
 
 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)

security/selinux/hooks.c

···
 	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,
···
 	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)
 {
···
 	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;
···
 	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)
···
 	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;
···
 	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)
···
 	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;
···
 	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)
···
 	.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 = {
···
 	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),

security/selinux/include/objsec.h

···
 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_ */

security/smack/smack.h

···
 
 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;
 }
 
 /*

security/smack/smack_lsm.c

···
  */
 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;
 }
 
 /**
···
 
 	*blob = smk_of_current();
 	return 0;
-}
-
-/**
- * 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;
 }
 
 /**
···
 	.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 = {
···
 	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),