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>

2 files changed, 32 insertions, 25 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 15d73e47cc2c..ab4d0e598a2c 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -263,7 +263,7 @@ void xfrm_policy_destroy(struct xfrm_policy *policy)
         list_del(&policy->bytype);
         write_unlock_bh(&xfrm_policy_lock);
 
-        security_xfrm_policy_free(policy);
+        security_xfrm_policy_free(policy->security);
         kfree(policy);
 }
 EXPORT_SYMBOL(xfrm_policy_destroy);
@@ -676,7 +676,8 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(u8 type, int dir,
                     xfrm_sec_ctx_match(ctx, pol->security)) {
                         xfrm_pol_hold(pol);
                         if (delete) {
-                                *err = security_xfrm_policy_delete(pol);
+                                *err = security_xfrm_policy_delete(
+                                                                pol->security);
                                 if (*err) {
                                         write_unlock_bh(&xfrm_policy_lock);
                                         return pol;
@@ -718,7 +719,8 @@ struct xfrm_policy *xfrm_policy_byid(u8 type, int dir, u32 id, int delete,
                 if (pol->type == type && pol->index == id) {
                         xfrm_pol_hold(pol);
                         if (delete) {
-                                *err = security_xfrm_policy_delete(pol);
+                                *err = security_xfrm_policy_delete(
+                                                                pol->security);
                                 if (*err) {
                                         write_unlock_bh(&xfrm_policy_lock);
                                         return pol;
@@ -756,7 +758,7 @@ xfrm_policy_flush_secctx_check(u8 type, struct xfrm_audit *audit_info)
                                      &xfrm_policy_inexact[dir], bydst) {
                         if (pol->type != type)
                                 continue;
-                        err = security_xfrm_policy_delete(pol);
+                        err = security_xfrm_policy_delete(pol->security);
                         if (err) {
                                 xfrm_audit_policy_delete(pol, 0,
                                                          audit_info->loginuid,
@@ -770,7 +772,8 @@ xfrm_policy_flush_secctx_check(u8 type, struct xfrm_audit *audit_info)
                                              bydst) {
                                 if (pol->type != type)
                                         continue;
-                                err = security_xfrm_policy_delete(pol);
+                                err = security_xfrm_policy_delete(
+                                                                pol->security);
                                 if (err) {
                                         xfrm_audit_policy_delete(pol, 0,
                                                         audit_info->loginuid,
@@ -931,7 +934,8 @@ static int xfrm_policy_match(struct xfrm_policy *pol, struct flowi *fl,
 
         match = xfrm_selector_match(sel, fl, family);
         if (match)
-                ret = security_xfrm_policy_lookup(pol, fl->secid, dir);
+                ret = security_xfrm_policy_lookup(pol->security, fl->secid,
+                                                  dir);
 
         return ret;
 }
@@ -1048,8 +1052,9 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(struct sock *sk, int dir, struc
                 int err = 0;
 
                 if (match) {
-                        err = security_xfrm_policy_lookup(pol, fl->secid,
-                                        policy_to_flow_dir(dir));
+                        err = security_xfrm_policy_lookup(pol->security,
+                                                      fl->secid,
+                                                      policy_to_flow_dir(dir));
                         if (!err)
                                 xfrm_pol_hold(pol);
                         else if (err == -ESRCH)
@@ -1138,7 +1143,8 @@ static struct xfrm_policy *clone_policy(struct xfrm_policy *old, int dir)
 
         if (newp) {
                 newp->selector = old->selector;
-                if (security_xfrm_policy_clone(old, newp)) {
+                if (security_xfrm_policy_clone(old->security,
+                                               &newp->security)) {
                         kfree(newp);
                         return NULL;  /* ENOMEM */
                 }
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 5578c909fcf6..ecf9d67daef5 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -959,7 +959,7 @@ static int copy_from_user_sec_ctx(struct xfrm_policy *pol, struct nlattr **attrs
                 return 0;
 
         uctx = nla_data(rt);
-        return security_xfrm_policy_alloc(pol, uctx);
+        return security_xfrm_policy_alloc(&pol->security, uctx);
 }
 
 static void copy_templates(struct xfrm_policy *xp, struct xfrm_user_tmpl *ut,
@@ -1143,7 +1143,7 @@ static int xfrm_add_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
                               NETLINK_CB(skb).sid);
 
         if (err) {
-                security_xfrm_policy_free(xp);
+                security_xfrm_policy_free(xp->security);
                 kfree(xp);
                 return err;
         }
@@ -1337,22 +1337,23 @@ static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
                 xp = xfrm_policy_byid(type, p->dir, p->index, delete, &err);
         else {
                 struct nlattr *rt = attrs[XFRMA_SEC_CTX];
-                struct xfrm_policy tmp;
+                struct xfrm_sec_ctx *ctx;
 
                 err = verify_sec_ctx_len(attrs);
                 if (err)
                         return err;
 
-                memset(&tmp, 0, sizeof(struct xfrm_policy));
                 if (rt) {
                         struct xfrm_user_sec_ctx *uctx = nla_data(rt);
 
-                        if ((err = security_xfrm_policy_alloc(&tmp, uctx)))
+                        err = security_xfrm_policy_alloc(&ctx, uctx);
+                        if (err)
                                 return err;
-                }
-                xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, tmp.security,
+                } else
+                        ctx = NULL;
+                xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, ctx,
                                            delete, &err);
-                security_xfrm_policy_free(&tmp);
+                security_xfrm_policy_free(ctx);
         }
         if (xp == NULL)
                 return -ENOENT;
@@ -1572,26 +1573,26 @@ static int xfrm_add_pol_expire(struct sk_buff *skb, struct nlmsghdr *nlh,
                 xp = xfrm_policy_byid(type, p->dir, p->index, 0, &err);
         else {
                 struct nlattr *rt = attrs[XFRMA_SEC_CTX];
-                struct xfrm_policy tmp;
+                struct xfrm_sec_ctx *ctx;
 
                 err = verify_sec_ctx_len(attrs);
                 if (err)
                         return err;
 
-                memset(&tmp, 0, sizeof(struct xfrm_policy));
                 if (rt) {
                         struct xfrm_user_sec_ctx *uctx = nla_data(rt);
 
-                        if ((err = security_xfrm_policy_alloc(&tmp, uctx)))
+                        err = security_xfrm_policy_alloc(&ctx, uctx);
+                        if (err)
                                 return err;
-                }
-                xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, tmp.security,
-                                           0, &err);
-                security_xfrm_policy_free(&tmp);
+                } else
+                        ctx = NULL;
+                xp = xfrm_policy_bysel_ctx(type, p->dir, &p->sel, ctx, 0, &err);
+                security_xfrm_policy_free(ctx);
         }
-
         if (xp == NULL)
                 return -ENOENT;
+
         read_lock(&xp->lock);
         if (xp->dead) {
                 read_unlock(&xp->lock);