[PATCH v5 36/38] Smack: Abstract use of ipc security blobs

[Casey Schaufler]

Don't use the ipc->security pointer directly.
Don't use the msg_msg->security pointer directly.
Provide helper functions that provides the security blob pointers.

Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
Reviewed-by: Kees Cook <keescook at chromium.org>
Signed-off-by: Kees Cook <keescook at chromium.org>
---
 security/smack/smack.h     | 11 +++++++++++
 security/smack/smack_lsm.c | 14 +++++++++-----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/security/smack/smack.h b/security/smack/smack.h
index bf0abc35ca1c..0adddbeecc62 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -24,6 +24,7 @@
 #include <linux/list.h>
 #include <linux/rculist.h>
 #include <linux/lsm_audit.h>
+#include <linux/msg.h>
 
 /*
  * Use IPv6 port labeling if IPv6 is enabled and secmarks
@@ -373,6 +374,16 @@ static inline struct inode_smack *smack_inode(const struct inode *inode)
 	return inode->i_security + smack_blob_sizes.lbs_inode;
 }
 
+static inline struct smack_known **smack_msg_msg(const struct msg_msg *msg)
+{
+	return (struct smack_known **)&msg->security;
+}
+
+static inline struct smack_known **smack_ipc(const struct kern_ipc_perm *ipc)
+{
+	return (struct smack_known **)&ipc->security;
+}
+
 /*
  * Is the directory transmuting?
  */
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 9ff185af378a..ceda326a6e47 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2918,7 +2918,9 @@ static void smack_msg_msg_free_security(struct msg_msg *msg)
  */
 static struct smack_known *smack_of_ipc(struct kern_ipc_perm *isp)
 {
-	return (struct smack_known *)isp->security;
+	struct smack_known **blob = smack_ipc(isp);
+
+	return *blob;
 }
 
 /**
@@ -2929,9 +2931,9 @@ static struct smack_known *smack_of_ipc(struct kern_ipc_perm *isp)
  */
 static int smack_ipc_alloc_security(struct kern_ipc_perm *isp)
 {
-	struct smack_known *skp = smk_of_current();
+	struct smack_known **blob = smack_ipc(isp);
 
-	isp->security = skp;
+	*blob = smk_of_current();
 	return 0;
 }
 
@@ -3243,7 +3245,8 @@ static int smack_msg_queue_msgrcv(struct kern_ipc_perm *isp, struct msg_msg *msg
  */
 static int smack_ipc_permission(struct kern_ipc_perm *ipp, short flag)
 {
-	struct smack_known *iskp = ipp->security;
+	struct smack_known **blob = smack_ipc(ipp);
+	struct smack_known *iskp = *blob;
 	int may = smack_flags_to_may(flag);
 	struct smk_audit_info ad;
 	int rc;
@@ -3264,7 +3267,8 @@ static int smack_ipc_permission(struct kern_ipc_perm *ipp, short flag)
  */
 static void smack_ipc_getsecid(struct kern_ipc_perm *ipp, u32 *secid)
 {
-	struct smack_known *iskp = ipp->security;
+	struct smack_known **blob = smack_ipc(ipp);
+	struct smack_known *iskp = *blob;
 
 	*secid = iskp->smk_secid;
 }
-- 
2.14.5