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

From: Casey Schaufler
Date: Tue Dec 11 2018 - 17:44:40 EST


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@xxxxxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
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