diff mbox series

[v2,2/6] LSM: Infrastructure management of the key security blob

Message ID 20240710213230.11978-3-casey@schaufler-ca.com (mailing list archive)
State Accepted
Delegated to: Paul Moore
Headers show
Series LSM: Infrastructure blob allocation | expand

Commit Message

Casey Schaufler July 10, 2024, 9:32 p.m. UTC 
Move management of the key->security blob 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.  There are
no existing modules that require a key_free hook, so the call to it and
the definition for it have been removed.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/lsm_hook_defs.h     |  1 -
 include/linux/lsm_hooks.h         |  1 +
 security/security.c               | 39 +++++++++++++++++++++++++++++--
 security/selinux/hooks.c          | 21 ++++-------------
 security/selinux/include/objsec.h |  7 ++++++
 security/smack/smack.h            |  7 ++++++
 security/smack/smack_lsm.c        | 31 +++++++++++-------------
 7 files changed, 69 insertions(+), 38 deletions(-)

Comments

John Johansen July 10, 2024, 10:45 p.m. UTC | #1 
On 7/10/24 14:32, Casey Schaufler wrote:
> Move management of the key->security blob 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.  There are
> no existing modules that require a key_free hook, so the call to it and
> the definition for it have been removed.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

looks good

Reviewed-by: John Johansen <john.johansen@canonical.com>

> ---
>   include/linux/lsm_hook_defs.h     |  1 -
>   include/linux/lsm_hooks.h         |  1 +
>   security/security.c               | 39 +++++++++++++++++++++++++++++--
>   security/selinux/hooks.c          | 21 ++++-------------
>   security/selinux/include/objsec.h |  7 ++++++
>   security/smack/smack.h            |  7 ++++++
>   security/smack/smack_lsm.c        | 31 +++++++++++-------------
>   7 files changed, 69 insertions(+), 38 deletions(-)
> 
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index 44488b1ab9a9..cc81f7f7c024 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -402,7 +402,6 @@ LSM_HOOK(int, 0, xfrm_decode_session, struct sk_buff *skb, u32 *secid,
>   #ifdef CONFIG_KEYS
>   LSM_HOOK(int, 0, key_alloc, struct key *key, const struct cred *cred,
>   	 unsigned long flags)
> -LSM_HOOK(void, LSM_RET_VOID, key_free, struct key *key)
>   LSM_HOOK(int, 0, key_permission, key_ref_t key_ref, const struct cred *cred,
>   	 enum key_need_perm need_perm)
>   LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **buffer)
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index efd4a0655159..7233bc0737be 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -76,6 +76,7 @@ struct lsm_blob_sizes {
>   	int	lbs_sock;
>   	int	lbs_superblock;
>   	int	lbs_ipc;
> +	int	lbs_key;
>   	int	lbs_msg_msg;
>   	int	lbs_task;
>   	int	lbs_xattr_count; /* number of xattr slots in new_xattrs array */
> diff --git a/security/security.c b/security/security.c
> index 5e93a72bdca6..92068ebd7e2b 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -227,6 +227,7 @@ static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed)
>   		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_key, &blob_sizes.lbs_key);
>   	lsm_set_blob_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
>   	lsm_set_blob_size(&needed->lbs_sock, &blob_sizes.lbs_sock);
>   	lsm_set_blob_size(&needed->lbs_superblock, &blob_sizes.lbs_superblock);
> @@ -402,6 +403,9 @@ static void __init ordered_lsm_init(void)
>   	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);
> +#ifdef CONFIG_KEYS
> +	init_debug("key blob size        = %d\n", blob_sizes.lbs_key);
> +#endif /* CONFIG_KEYS */
>   	init_debug("msg_msg blob size    = %d\n", blob_sizes.lbs_msg_msg);
>   	init_debug("sock blob size       = %d\n", blob_sizes.lbs_sock);
>   	init_debug("superblock blob size = %d\n", blob_sizes.lbs_superblock);
> @@ -718,6 +722,29 @@ static int lsm_ipc_alloc(struct kern_ipc_perm *kip)
>   	return 0;
>   }
>   
> +#ifdef CONFIG_KEYS
> +/**
> + * lsm_key_alloc - allocate a composite key blob
> + * @key: the key that needs a blob
> + *
> + * Allocate the key blob for all the modules
> + *
> + * Returns 0, or -ENOMEM if memory can't be allocated.
> + */
> +static int lsm_key_alloc(struct key *key)
> +{
> +	if (blob_sizes.lbs_key == 0) {
> +		key->security = NULL;
> +		return 0;
> +	}
> +
> +	key->security = kzalloc(blob_sizes.lbs_key, GFP_KERNEL);
> +	if (key->security == NULL)
> +		return -ENOMEM;
> +	return 0;
> +}
> +#endif /* CONFIG_KEYS */
> +
>   /**
>    * lsm_msg_msg_alloc - allocate a composite msg_msg blob
>    * @mp: the msg_msg that needs a blob
> @@ -5290,7 +5317,14 @@ EXPORT_SYMBOL(security_skb_classify_flow);
>   int security_key_alloc(struct key *key, const struct cred *cred,
>   		       unsigned long flags)
>   {
> -	return call_int_hook(key_alloc, key, cred, flags);
> +	int rc = lsm_key_alloc(key);
> +
> +	if (unlikely(rc))
> +		return rc;
> +	rc = call_int_hook(key_alloc, key, cred, flags);
> +	if (unlikely(rc))
> +		security_key_free(key);
> +	return rc;
>   }
>   
>   /**
> @@ -5301,7 +5335,8 @@ int security_key_alloc(struct key *key, const struct cred *cred,
>    */
>   void security_key_free(struct key *key)
>   {
> -	call_void_hook(key_free, key);
> +	kfree(key->security);
> +	key->security = NULL;
>   }
>   
>   /**
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 19346e1817ff..986825ba1cc5 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6658,11 +6658,7 @@ static int selinux_key_alloc(struct key *k, const struct cred *cred,
>   			     unsigned long flags)
>   {
>   	const struct task_security_struct *tsec;
> -	struct key_security_struct *ksec;
> -
> -	ksec = kzalloc(sizeof(struct key_security_struct), GFP_KERNEL);
> -	if (!ksec)
> -		return -ENOMEM;
> +	struct key_security_struct *ksec = selinux_key(k);
>   
>   	tsec = selinux_cred(cred);
>   	if (tsec->keycreate_sid)
> @@ -6670,18 +6666,9 @@ static int selinux_key_alloc(struct key *k, const struct cred *cred,
>   	else
>   		ksec->sid = tsec->sid;
>   
> -	k->security = ksec;
>   	return 0;
>   }
>   
> -static void selinux_key_free(struct key *k)
> -{
> -	struct key_security_struct *ksec = k->security;
> -
> -	k->security = NULL;
> -	kfree(ksec);
> -}
> -
>   static int selinux_key_permission(key_ref_t key_ref,
>   				  const struct cred *cred,
>   				  enum key_need_perm need_perm)
> @@ -6722,14 +6709,14 @@ static int selinux_key_permission(key_ref_t key_ref,
>   
>   	sid = cred_sid(cred);
>   	key = key_ref_to_ptr(key_ref);
> -	ksec = key->security;
> +	ksec = selinux_key(key);
>   
>   	return avc_has_perm(sid, ksec->sid, SECCLASS_KEY, perm, NULL);
>   }
>   
>   static int selinux_key_getsecurity(struct key *key, char **_buffer)
>   {
> -	struct key_security_struct *ksec = key->security;
> +	struct key_security_struct *ksec = selinux_key(key);
>   	char *context = NULL;
>   	unsigned len;
>   	int rc;
> @@ -6981,6 +6968,7 @@ struct lsm_blob_sizes selinux_blob_sizes __ro_after_init = {
>   	.lbs_file = sizeof(struct file_security_struct),
>   	.lbs_inode = sizeof(struct inode_security_struct),
>   	.lbs_ipc = sizeof(struct ipc_security_struct),
> +	.lbs_key = sizeof(struct key_security_struct),
>   	.lbs_msg_msg = sizeof(struct msg_security_struct),
>   	.lbs_sock = sizeof(struct sk_security_struct),
>   	.lbs_superblock = sizeof(struct superblock_security_struct),
> @@ -7318,7 +7306,6 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = {
>   #endif
>   
>   #ifdef CONFIG_KEYS
> -	LSM_HOOK_INIT(key_free, selinux_key_free),
>   	LSM_HOOK_INIT(key_permission, selinux_key_permission),
>   	LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
>   #ifdef CONFIG_KEY_NOTIFICATIONS
> diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
> index b074099acbaf..83b9443d6919 100644
> --- a/security/selinux/include/objsec.h
> +++ b/security/selinux/include/objsec.h
> @@ -195,6 +195,13 @@ selinux_superblock(const struct super_block *superblock)
>   	return superblock->s_security + selinux_blob_sizes.lbs_superblock;
>   }
>   
> +#ifdef CONFIG_KEYS
> +static inline struct key_security_struct *selinux_key(const struct key *key)
> +{
> +	return key->security + selinux_blob_sizes.lbs_key;
> +}
> +#endif /* CONFIG_KEYS */
> +
>   static inline struct sk_security_struct *selinux_sock(const struct sock *sock)
>   {
>   	return sock->sk_security + selinux_blob_sizes.lbs_sock;
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index 297f21446f45..dbf8d7226eb5 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -360,6 +360,13 @@ static inline struct socket_smack *smack_sock(const struct sock *sock)
>   	return sock->sk_security + smack_blob_sizes.lbs_sock;
>   }
>   
> +#ifdef CONFIG_KEYS
> +static inline struct smack_known **smack_key(const struct key *key)
> +{
> +	return key->security + smack_blob_sizes.lbs_key;
> +}
> +#endif /* CONFIG_KEYS */
> +
>   /*
>    * Is the directory transmuting?
>    */
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index a931b44bc959..c57eacf1d3b1 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -4473,23 +4473,13 @@ static void smack_inet_csk_clone(struct sock *sk,
>   static int smack_key_alloc(struct key *key, const struct cred *cred,
>   			   unsigned long flags)
>   {
> +	struct smack_known **blob = smack_key(key);
>   	struct smack_known *skp = smk_of_task(smack_cred(cred));
>   
> -	key->security = skp;
> +	*blob = skp;
>   	return 0;
>   }
>   
> -/**
> - * smack_key_free - Clear the key security blob
> - * @key: the object
> - *
> - * Clear the blob pointer
> - */
> -static void smack_key_free(struct key *key)
> -{
> -	key->security = NULL;
> -}
> -
>   /**
>    * smack_key_permission - Smack access on a key
>    * @key_ref: gets to the object
> @@ -4503,6 +4493,8 @@ static int smack_key_permission(key_ref_t key_ref,
>   				const struct cred *cred,
>   				enum key_need_perm need_perm)
>   {
> +	struct smack_known **blob;
> +	struct smack_known *skp;
>   	struct key *keyp;
>   	struct smk_audit_info ad;
>   	struct smack_known *tkp = smk_of_task(smack_cred(cred));
> @@ -4540,7 +4532,9 @@ static int smack_key_permission(key_ref_t key_ref,
>   	 * If the key hasn't been initialized give it access so that
>   	 * it may do so.
>   	 */
> -	if (keyp->security == NULL)
> +	blob = smack_key(keyp);
> +	skp = *blob;
> +	if (skp == NULL)
>   		return 0;
>   	/*
>   	 * This should not occur
> @@ -4556,8 +4550,8 @@ static int smack_key_permission(key_ref_t key_ref,
>   	ad.a.u.key_struct.key = keyp->serial;
>   	ad.a.u.key_struct.key_desc = keyp->description;
>   #endif
> -	rc = smk_access(tkp, keyp->security, request, &ad);
> -	rc = smk_bu_note("key access", tkp, keyp->security, request, rc);
> +	rc = smk_access(tkp, skp, request, &ad);
> +	rc = smk_bu_note("key access", tkp, skp, request, rc);
>   	return rc;
>   }
>   
> @@ -4572,11 +4566,12 @@ static int smack_key_permission(key_ref_t key_ref,
>    */
>   static int smack_key_getsecurity(struct key *key, char **_buffer)
>   {
> -	struct smack_known *skp = key->security;
> +	struct smack_known **blob = smack_key(key);
> +	struct smack_known *skp = *blob;
>   	size_t length;
>   	char *copy;
>   
> -	if (key->security == NULL) {
> +	if (skp == NULL) {
>   		*_buffer = NULL;
>   		return 0;
>   	}
> @@ -5010,6 +5005,7 @@ struct lsm_blob_sizes smack_blob_sizes __ro_after_init = {
>   	.lbs_file = sizeof(struct smack_known *),
>   	.lbs_inode = sizeof(struct inode_smack),
>   	.lbs_ipc = sizeof(struct smack_known *),
> +	.lbs_key = sizeof(struct smack_known *),
>   	.lbs_msg_msg = sizeof(struct smack_known *),
>   	.lbs_sock = sizeof(struct socket_smack),
>   	.lbs_superblock = sizeof(struct superblock_smack),
> @@ -5146,7 +5142,6 @@ static struct security_hook_list smack_hooks[] __ro_after_init = {
>    /* key management security hooks */
>   #ifdef CONFIG_KEYS
>   	LSM_HOOK_INIT(key_alloc, smack_key_alloc),
> -	LSM_HOOK_INIT(key_free, smack_key_free),
>   	LSM_HOOK_INIT(key_permission, smack_key_permission),
>   	LSM_HOOK_INIT(key_getsecurity, smack_key_getsecurity),
>   #ifdef CONFIG_KEY_NOTIFICATIONS
diff mbox series

Patch

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 44488b1ab9a9..cc81f7f7c024 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -402,7 +402,6 @@  LSM_HOOK(int, 0, xfrm_decode_session, struct sk_buff *skb, u32 *secid,
 #ifdef CONFIG_KEYS
 LSM_HOOK(int, 0, key_alloc, struct key *key, const struct cred *cred,
 	 unsigned long flags)
-LSM_HOOK(void, LSM_RET_VOID, key_free, struct key *key)
 LSM_HOOK(int, 0, key_permission, key_ref_t key_ref, const struct cred *cred,
 	 enum key_need_perm need_perm)
 LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **buffer)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index efd4a0655159..7233bc0737be 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -76,6 +76,7 @@  struct lsm_blob_sizes {
 	int	lbs_sock;
 	int	lbs_superblock;
 	int	lbs_ipc;
+	int	lbs_key;
 	int	lbs_msg_msg;
 	int	lbs_task;
 	int	lbs_xattr_count; /* number of xattr slots in new_xattrs array */
diff --git a/security/security.c b/security/security.c
index 5e93a72bdca6..92068ebd7e2b 100644
--- a/security/security.c
+++ b/security/security.c
@@ -227,6 +227,7 @@  static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed)
 		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_key, &blob_sizes.lbs_key);
 	lsm_set_blob_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
 	lsm_set_blob_size(&needed->lbs_sock, &blob_sizes.lbs_sock);
 	lsm_set_blob_size(&needed->lbs_superblock, &blob_sizes.lbs_superblock);
@@ -402,6 +403,9 @@  static void __init ordered_lsm_init(void)
 	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);
+#ifdef CONFIG_KEYS
+	init_debug("key blob size        = %d\n", blob_sizes.lbs_key);
+#endif /* CONFIG_KEYS */
 	init_debug("msg_msg blob size    = %d\n", blob_sizes.lbs_msg_msg);
 	init_debug("sock blob size       = %d\n", blob_sizes.lbs_sock);
 	init_debug("superblock blob size = %d\n", blob_sizes.lbs_superblock);
@@ -718,6 +722,29 @@  static int lsm_ipc_alloc(struct kern_ipc_perm *kip)
 	return 0;
 }
 
+#ifdef CONFIG_KEYS
+/**
+ * lsm_key_alloc - allocate a composite key blob
+ * @key: the key that needs a blob
+ *
+ * Allocate the key blob for all the modules
+ *
+ * Returns 0, or -ENOMEM if memory can't be allocated.
+ */
+static int lsm_key_alloc(struct key *key)
+{
+	if (blob_sizes.lbs_key == 0) {
+		key->security = NULL;
+		return 0;
+	}
+
+	key->security = kzalloc(blob_sizes.lbs_key, GFP_KERNEL);
+	if (key->security == NULL)
+		return -ENOMEM;
+	return 0;
+}
+#endif /* CONFIG_KEYS */
+
 /**
  * lsm_msg_msg_alloc - allocate a composite msg_msg blob
  * @mp: the msg_msg that needs a blob
@@ -5290,7 +5317,14 @@  EXPORT_SYMBOL(security_skb_classify_flow);
 int security_key_alloc(struct key *key, const struct cred *cred,
 		       unsigned long flags)
 {
-	return call_int_hook(key_alloc, key, cred, flags);
+	int rc = lsm_key_alloc(key);
+
+	if (unlikely(rc))
+		return rc;
+	rc = call_int_hook(key_alloc, key, cred, flags);
+	if (unlikely(rc))
+		security_key_free(key);
+	return rc;
 }
 
 /**
@@ -5301,7 +5335,8 @@  int security_key_alloc(struct key *key, const struct cred *cred,
  */
 void security_key_free(struct key *key)
 {
-	call_void_hook(key_free, key);
+	kfree(key->security);
+	key->security = NULL;
 }
 
 /**
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 19346e1817ff..986825ba1cc5 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6658,11 +6658,7 @@  static int selinux_key_alloc(struct key *k, const struct cred *cred,
 			     unsigned long flags)
 {
 	const struct task_security_struct *tsec;
-	struct key_security_struct *ksec;
-
-	ksec = kzalloc(sizeof(struct key_security_struct), GFP_KERNEL);
-	if (!ksec)
-		return -ENOMEM;
+	struct key_security_struct *ksec = selinux_key(k);
 
 	tsec = selinux_cred(cred);
 	if (tsec->keycreate_sid)
@@ -6670,18 +6666,9 @@  static int selinux_key_alloc(struct key *k, const struct cred *cred,
 	else
 		ksec->sid = tsec->sid;
 
-	k->security = ksec;
 	return 0;
 }
 
-static void selinux_key_free(struct key *k)
-{
-	struct key_security_struct *ksec = k->security;
-
-	k->security = NULL;
-	kfree(ksec);
-}
-
 static int selinux_key_permission(key_ref_t key_ref,
 				  const struct cred *cred,
 				  enum key_need_perm need_perm)
@@ -6722,14 +6709,14 @@  static int selinux_key_permission(key_ref_t key_ref,
 
 	sid = cred_sid(cred);
 	key = key_ref_to_ptr(key_ref);
-	ksec = key->security;
+	ksec = selinux_key(key);
 
 	return avc_has_perm(sid, ksec->sid, SECCLASS_KEY, perm, NULL);
 }
 
 static int selinux_key_getsecurity(struct key *key, char **_buffer)
 {
-	struct key_security_struct *ksec = key->security;
+	struct key_security_struct *ksec = selinux_key(key);
 	char *context = NULL;
 	unsigned len;
 	int rc;
@@ -6981,6 +6968,7 @@  struct lsm_blob_sizes selinux_blob_sizes __ro_after_init = {
 	.lbs_file = sizeof(struct file_security_struct),
 	.lbs_inode = sizeof(struct inode_security_struct),
 	.lbs_ipc = sizeof(struct ipc_security_struct),
+	.lbs_key = sizeof(struct key_security_struct),
 	.lbs_msg_msg = sizeof(struct msg_security_struct),
 	.lbs_sock = sizeof(struct sk_security_struct),
 	.lbs_superblock = sizeof(struct superblock_security_struct),
@@ -7318,7 +7306,6 @@  static struct security_hook_list selinux_hooks[] __ro_after_init = {
 #endif
 
 #ifdef CONFIG_KEYS
-	LSM_HOOK_INIT(key_free, selinux_key_free),
 	LSM_HOOK_INIT(key_permission, selinux_key_permission),
 	LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
 #ifdef CONFIG_KEY_NOTIFICATIONS
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index b074099acbaf..83b9443d6919 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -195,6 +195,13 @@  selinux_superblock(const struct super_block *superblock)
 	return superblock->s_security + selinux_blob_sizes.lbs_superblock;
 }
 
+#ifdef CONFIG_KEYS
+static inline struct key_security_struct *selinux_key(const struct key *key)
+{
+	return key->security + selinux_blob_sizes.lbs_key;
+}
+#endif /* CONFIG_KEYS */
+
 static inline struct sk_security_struct *selinux_sock(const struct sock *sock)
 {
 	return sock->sk_security + selinux_blob_sizes.lbs_sock;
diff --git a/security/smack/smack.h b/security/smack/smack.h
index 297f21446f45..dbf8d7226eb5 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -360,6 +360,13 @@  static inline struct socket_smack *smack_sock(const struct sock *sock)
 	return sock->sk_security + smack_blob_sizes.lbs_sock;
 }
 
+#ifdef CONFIG_KEYS
+static inline struct smack_known **smack_key(const struct key *key)
+{
+	return key->security + smack_blob_sizes.lbs_key;
+}
+#endif /* CONFIG_KEYS */
+
 /*
  * Is the directory transmuting?
  */
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index a931b44bc959..c57eacf1d3b1 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4473,23 +4473,13 @@  static void smack_inet_csk_clone(struct sock *sk,
 static int smack_key_alloc(struct key *key, const struct cred *cred,
 			   unsigned long flags)
 {
+	struct smack_known **blob = smack_key(key);
 	struct smack_known *skp = smk_of_task(smack_cred(cred));
 
-	key->security = skp;
+	*blob = skp;
 	return 0;
 }
 
-/**
- * smack_key_free - Clear the key security blob
- * @key: the object
- *
- * Clear the blob pointer
- */
-static void smack_key_free(struct key *key)
-{
-	key->security = NULL;
-}
-
 /**
  * smack_key_permission - Smack access on a key
  * @key_ref: gets to the object
@@ -4503,6 +4493,8 @@  static int smack_key_permission(key_ref_t key_ref,
 				const struct cred *cred,
 				enum key_need_perm need_perm)
 {
+	struct smack_known **blob;
+	struct smack_known *skp;
 	struct key *keyp;
 	struct smk_audit_info ad;
 	struct smack_known *tkp = smk_of_task(smack_cred(cred));
@@ -4540,7 +4532,9 @@  static int smack_key_permission(key_ref_t key_ref,
 	 * If the key hasn't been initialized give it access so that
 	 * it may do so.
 	 */
-	if (keyp->security == NULL)
+	blob = smack_key(keyp);
+	skp = *blob;
+	if (skp == NULL)
 		return 0;
 	/*
 	 * This should not occur
@@ -4556,8 +4550,8 @@  static int smack_key_permission(key_ref_t key_ref,
 	ad.a.u.key_struct.key = keyp->serial;
 	ad.a.u.key_struct.key_desc = keyp->description;
 #endif
-	rc = smk_access(tkp, keyp->security, request, &ad);
-	rc = smk_bu_note("key access", tkp, keyp->security, request, rc);
+	rc = smk_access(tkp, skp, request, &ad);
+	rc = smk_bu_note("key access", tkp, skp, request, rc);
 	return rc;
 }
 
@@ -4572,11 +4566,12 @@  static int smack_key_permission(key_ref_t key_ref,
  */
 static int smack_key_getsecurity(struct key *key, char **_buffer)
 {
-	struct smack_known *skp = key->security;
+	struct smack_known **blob = smack_key(key);
+	struct smack_known *skp = *blob;
 	size_t length;
 	char *copy;
 
-	if (key->security == NULL) {
+	if (skp == NULL) {
 		*_buffer = NULL;
 		return 0;
 	}
@@ -5010,6 +5005,7 @@  struct lsm_blob_sizes smack_blob_sizes __ro_after_init = {
 	.lbs_file = sizeof(struct smack_known *),
 	.lbs_inode = sizeof(struct inode_smack),
 	.lbs_ipc = sizeof(struct smack_known *),
+	.lbs_key = sizeof(struct smack_known *),
 	.lbs_msg_msg = sizeof(struct smack_known *),
 	.lbs_sock = sizeof(struct socket_smack),
 	.lbs_superblock = sizeof(struct superblock_smack),
@@ -5146,7 +5142,6 @@  static struct security_hook_list smack_hooks[] __ro_after_init = {
  /* key management security hooks */
 #ifdef CONFIG_KEYS
 	LSM_HOOK_INIT(key_alloc, smack_key_alloc),
-	LSM_HOOK_INIT(key_free, smack_key_free),
 	LSM_HOOK_INIT(key_permission, smack_key_permission),
 	LSM_HOOK_INIT(key_getsecurity, smack_key_getsecurity),
 #ifdef CONFIG_KEY_NOTIFICATIONS