LSM: Make the Labeled IPsec hooks more stack friendly

The xfrm_get_policy() and xfrm_add_pol_expire() put some rather large structs
on the stack to work around the LSM API.  This patch attempts to fix that
problem by changing the LSM API to require only the relevant "security"
pointers instead of the entire SPD entry; we do this for all of the
security_xfrm_policy*() functions to keep things consistent.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 42 insertions, 45 deletions

diff --git a/security/dummy.c b/security/dummy.c
index 78d8f92310a4..480366f9c41d 100644
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -876,22 +876,23 @@ static inline void dummy_req_classify_flow(const struct request_sock *req,
 #endif  /* CONFIG_SECURITY_NETWORK */
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
-static int dummy_xfrm_policy_alloc_security(struct xfrm_policy *xp,
-                struct xfrm_user_sec_ctx *sec_ctx)
+static int dummy_xfrm_policy_alloc_security(struct xfrm_sec_ctx **ctxp,
+                                            struct xfrm_user_sec_ctx *sec_ctx)
 {
         return 0;
 }
 
-static inline int dummy_xfrm_policy_clone_security(struct xfrm_policy *old, struct xfrm_policy *new)
+static inline int dummy_xfrm_policy_clone_security(struct xfrm_sec_ctx *old_ctx,
+                                           struct xfrm_sec_ctx **new_ctxp)
 {
         return 0;
 }
 
-static void dummy_xfrm_policy_free_security(struct xfrm_policy *xp)
+static void dummy_xfrm_policy_free_security(struct xfrm_sec_ctx *ctx)
 {
 }
 
-static int dummy_xfrm_policy_delete_security(struct xfrm_policy *xp)
+static int dummy_xfrm_policy_delete_security(struct xfrm_sec_ctx *ctx)
 {
         return 0;
 }
@@ -911,7 +912,8 @@ static int dummy_xfrm_state_delete_security(struct xfrm_state *x)
         return 0;
 }
 
-static int dummy_xfrm_policy_lookup(struct xfrm_policy *xp, u32 sk_sid, u8 dir)
+static int dummy_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx,
+                                    u32 sk_sid, u8 dir)
 {
         return 0;
 }
diff --git a/security/security.c b/security/security.c
index b1387a6b416d..c9ff7d18c2f4 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1014,26 +1014,27 @@ void security_inet_conn_established(struct sock *sk,
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
 
-int security_xfrm_policy_alloc(struct xfrm_policy *xp, struct xfrm_user_sec_ctx *sec_ctx)
+int security_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp, struct xfrm_user_sec_ctx *sec_ctx)
 {
-        return security_ops->xfrm_policy_alloc_security(xp, sec_ctx);
+        return security_ops->xfrm_policy_alloc_security(ctxp, sec_ctx);
 }
 EXPORT_SYMBOL(security_xfrm_policy_alloc);
 
-int security_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
+int security_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
+                              struct xfrm_sec_ctx **new_ctxp)
 {
-        return security_ops->xfrm_policy_clone_security(old, new);
+        return security_ops->xfrm_policy_clone_security(old_ctx, new_ctxp);
 }
 
-void security_xfrm_policy_free(struct xfrm_policy *xp)
+void security_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
 {
-        security_ops->xfrm_policy_free_security(xp);
+        security_ops->xfrm_policy_free_security(ctx);
 }
 EXPORT_SYMBOL(security_xfrm_policy_free);
 
-int security_xfrm_policy_delete(struct xfrm_policy *xp)
+int security_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
 {
-        return security_ops->xfrm_policy_delete_security(xp);
+        return security_ops->xfrm_policy_delete_security(ctx);
 }
 
 int security_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *sec_ctx)
@@ -1065,9 +1066,9 @@ void security_xfrm_state_free(struct xfrm_state *x)
         security_ops->xfrm_state_free_security(x);
 }
 
-int security_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir)
+int security_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
 {
-        return security_ops->xfrm_policy_lookup(xp, fl_secid, dir);
+        return security_ops->xfrm_policy_lookup(ctx, fl_secid, dir);
 }
 
 int security_xfrm_state_pol_flow_match(struct xfrm_state *x,
diff --git a/security/selinux/include/xfrm.h b/security/selinux/include/xfrm.h
index 36b0510efa7b..289e24b39e3e 100644
--- a/security/selinux/include/xfrm.h
+++ b/security/selinux/include/xfrm.h
@@ -7,16 +7,17 @@
 #ifndef _SELINUX_XFRM_H_
 #define _SELINUX_XFRM_H_
 
-int selinux_xfrm_policy_alloc(struct xfrm_policy *xp,
-                struct xfrm_user_sec_ctx *sec_ctx);
-int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new);
-void selinux_xfrm_policy_free(struct xfrm_policy *xp);
-int selinux_xfrm_policy_delete(struct xfrm_policy *xp);
+int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
+                              struct xfrm_user_sec_ctx *sec_ctx);
+int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
+                              struct xfrm_sec_ctx **new_ctxp);
+void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx);
+int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx);
 int selinux_xfrm_state_alloc(struct xfrm_state *x,
         struct xfrm_user_sec_ctx *sec_ctx, u32 secid);
 void selinux_xfrm_state_free(struct xfrm_state *x);
 int selinux_xfrm_state_delete(struct xfrm_state *x);
-int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir);
+int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir);
 int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
                         struct xfrm_policy *xp, struct flowi *fl);
 
diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
index 7e158205d081..874d17c83c61 100644
--- a/security/selinux/xfrm.c
+++ b/security/selinux/xfrm.c
@@ -77,20 +77,18 @@ static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
  * LSM hook implementation that authorizes that a flow can use
  * a xfrm policy rule.
  */
-int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir)
+int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
 {
         int rc;
         u32 sel_sid;
-        struct xfrm_sec_ctx *ctx;
 
         /* Context sid is either set to label or ANY_ASSOC */
-        if ((ctx = xp->security)) {
+        if (ctx) {
                 if (!selinux_authorizable_ctx(ctx))
                         return -EINVAL;
 
                 sel_sid = ctx->ctx_sid;
-        }
-        else
+        } else
                 /*
                  * All flows should be treated as polmatch'ing an
                  * otherwise applicable "non-labeled" policy. This
@@ -103,7 +101,7 @@ int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir)
                           NULL);
 
         if (rc == -EACCES)
-                rc = -ESRCH;
+                return -ESRCH;
 
         return rc;
 }
@@ -287,15 +285,14 @@ out2:
  * LSM hook implementation that allocs and transfers uctx spec to
  * xfrm_policy.
  */
-int selinux_xfrm_policy_alloc(struct xfrm_policy *xp,
-                struct xfrm_user_sec_ctx *uctx)
+int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
+                              struct xfrm_user_sec_ctx *uctx)
 {
         int err;
 
-        BUG_ON(!xp);
         BUG_ON(!uctx);
 
-        err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, 0);
+        err = selinux_xfrm_sec_ctx_alloc(ctxp, uctx, 0);
         if (err == 0)
                 atomic_inc(&selinux_xfrm_refcount);
 
@@ -307,32 +304,29 @@ int selinux_xfrm_policy_alloc(struct xfrm_policy *xp,
  * LSM hook implementation that copies security data structure from old to
  * new for policy cloning.
  */
-int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
+int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
+                              struct xfrm_sec_ctx **new_ctxp)
 {
-        struct xfrm_sec_ctx *old_ctx, *new_ctx;
-
-        old_ctx = old->security;
+        struct xfrm_sec_ctx *new_ctx;
 
         if (old_ctx) {
-                new_ctx = new->security = kmalloc(sizeof(*new_ctx) +
-                                                  old_ctx->ctx_len,
-                                                  GFP_KERNEL);
-
+                new_ctx = kmalloc(sizeof(*old_ctx) + old_ctx->ctx_len,
+                                  GFP_KERNEL);
                 if (!new_ctx)
                         return -ENOMEM;
 
                 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
                 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
+                *new_ctxp = new_ctx;
         }
         return 0;
 }
 
 /*
- * LSM hook implementation that frees xfrm_policy security information.
+ * LSM hook implementation that frees xfrm_sec_ctx security information.
  */
-void selinux_xfrm_policy_free(struct xfrm_policy *xp)
+void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
 {
-        struct xfrm_sec_ctx *ctx = xp->security;
         if (ctx)
                 kfree(ctx);
 }
@@ -340,10 +334,9 @@ void selinux_xfrm_policy_free(struct xfrm_policy *xp)
 /*
  * LSM hook implementation that authorizes deletion of labeled policies.
  */
-int selinux_xfrm_policy_delete(struct xfrm_policy *xp)
+int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
 {
         struct task_security_struct *tsec = current->security;
-        struct xfrm_sec_ctx *ctx = xp->security;
         int rc = 0;
 
         if (ctx) {