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>

1 files changed, 11 insertions, 12 deletions

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 6db58924368a..1fb0fe42a72e 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2292,7 +2292,7 @@ static int pfkey_spdadd(struct sock *sk, struct sk_buff *skb, struct sadb_msg *h
                         goto out;
                 }
 
-                err = security_xfrm_policy_alloc(xp, uctx);
+                err = security_xfrm_policy_alloc(&xp->security, uctx);
                 kfree(uctx);
 
                 if (err)
@@ -2352,10 +2352,11 @@ static int pfkey_spddelete(struct sock *sk, struct sk_buff *skb, struct sadb_msg
         int err;
         struct sadb_address *sa;
         struct sadb_x_policy *pol;
-        struct xfrm_policy *xp, tmp;
+        struct xfrm_policy *xp;
         struct xfrm_selector sel;
         struct km_event c;
         struct sadb_x_sec_ctx *sec_ctx;
+        struct xfrm_sec_ctx *pol_ctx;
 
         if (!present_and_same_family(ext_hdrs[SADB_EXT_ADDRESS_SRC-1],
                                      ext_hdrs[SADB_EXT_ADDRESS_DST-1]) ||
@@ -2385,25 +2386,23 @@ static int pfkey_spddelete(struct sock *sk, struct sk_buff *skb, struct sadb_msg
                 sel.dport_mask = htons(0xffff);
 
         sec_ctx = (struct sadb_x_sec_ctx *) ext_hdrs[SADB_X_EXT_SEC_CTX-1];
-        memset(&tmp, 0, sizeof(struct xfrm_policy));
-
         if (sec_ctx != NULL) {
                 struct xfrm_user_sec_ctx *uctx = pfkey_sadb2xfrm_user_sec_ctx(sec_ctx);
 
                 if (!uctx)
                         return -ENOMEM;
 
-                err = security_xfrm_policy_alloc(&tmp, uctx);
+                err = security_xfrm_policy_alloc(&pol_ctx, uctx);
                 kfree(uctx);
-
                 if (err)
                         return err;
-        }
-
-        xp = xfrm_policy_bysel_ctx(XFRM_POLICY_TYPE_MAIN, pol->sadb_x_policy_dir-1,
-                                   &sel, tmp.security, 1, &err);
-        security_xfrm_policy_free(&tmp);
+        } else
+                pol_ctx = NULL;
 
+        xp = xfrm_policy_bysel_ctx(XFRM_POLICY_TYPE_MAIN,
+                                   pol->sadb_x_policy_dir - 1, &sel, pol_ctx,
+                                   1, &err);
+        security_xfrm_policy_free(pol_ctx);
         if (xp == NULL)
                 return -ENOENT;
 
@@ -3298,7 +3297,7 @@ static struct xfrm_policy *pfkey_compile_policy(struct sock *sk, int opt,
                 if ((*dir = verify_sec_ctx_len(p)))
                         goto out;
                 uctx = pfkey_sadb2xfrm_user_sec_ctx(sec_ctx);
-                *dir = security_xfrm_policy_alloc(xp, uctx);
+                *dir = security_xfrm_policy_alloc(&xp->security, uctx);
                 kfree(uctx);
 
                 if (*dir)