selinux: fix the labeled xfrm/IPsec reference count handling

The SELinux labeled IPsec code was improperly handling its reference counting, dropping a reference on a delete operation instead of on a free/release operation. Reported-by: Ondrej Moris <omoris@redhat.com> Signed-off-by: Paul Moore <pmoore@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>

Author: pcmoore

security/selinux/xfrm.c

@@ -316,6 +316,7 @@ int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
 
 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
+atomic_inc(&selinux_xfrm_refcount);
 *new_ctxp = new_ctx;
 }
 return 0;
@@ -326,6 +327,7 @@ int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
  */
 void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
 {
+atomic_dec(&selinux_xfrm_refcount);
 kfree(ctx);
 }
 
@@ -335,17 +337,13 @@ void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
 int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
 {
 const struct task_security_struct *tsec = current_security();
-int rc = 0;
 
-if (ctx) {
-rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
- SECCLASS_ASSOCIATION,
- ASSOCIATION__SETCONTEXT, NULL);
-if (rc == 0)
-atomic_dec(&selinux_xfrm_refcount);
-}
+if (!ctx)
+return 0;
 
-return rc;
+return avc_has_perm(tsec->sid, ctx->ctx_sid,
+ SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
+ NULL);
 }
 
 /*
@@ -370,8 +368,8 @@ int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uct
  */
 void selinux_xfrm_state_free(struct xfrm_state *x)
 {
-struct xfrm_sec_ctx *ctx = x->security;
-kfree(ctx);
+atomic_dec(&selinux_xfrm_refcount);
+kfree(x->security);
 }
 
  /*
@@ -381,17 +379,13 @@ int selinux_xfrm_state_delete(struct xfrm_state *x)
 {
 const struct task_security_struct *tsec = current_security();
 struct xfrm_sec_ctx *ctx = x->security;
-int rc = 0;
 
-if (ctx) {
-rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
- SECCLASS_ASSOCIATION,
- ASSOCIATION__SETCONTEXT, NULL);
-if (rc == 0)
-atomic_dec(&selinux_xfrm_refcount);
-}
+if (!ctx)
+return 0;
 
-return rc;
+return avc_has_perm(tsec->sid, ctx->ctx_sid,
+ SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
+ NULL);
 }
 
 /*