xfrm: Generate queueing routes only from route lookup functions

Currently we genarate a queueing route if we have matching policies
but can not resolve the states and the sysctl xfrm_larval_drop is
disabled. Here we assume that dst_output() is called to kill the
queued packets. Unfortunately this assumption is not true in all
cases, so it is possible that these packets leave the system unwanted.

We fix this by generating queueing routes only from the
route lookup functions, here we can guarantee a call to
dst_output() afterwards.

Fixes: a0073fe18e71 ("xfrm: Add a state resolution packet queue")
Reported-by: Konstantinos Kolelis <k.kolelis@sirrix.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/include/net/dst.h b/include/net/dst.h
index fa11c904d2196582dbb3eda6274d6173a6920e51..a8ae4e760778d8fe49ff21951bd1e088ac3aefca 100644 (file)
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -480,6 +480,7 @@ void dst_init(void);
 /* Flags for xfrm_lookup flags argument. */
 enum {
        XFRM_LOOKUP_ICMP = 1 << 0,
+       XFRM_LOOKUP_QUEUE = 1 << 1,
 };
 
 struct flowi;

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 7505674c9faade563484e27559e0ac6c1d45f526..fdde51f4271adf22b26e36c46f76c2b93c4ce56e 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -39,6 +39,11 @@
 #define XFRM_QUEUE_TMO_MAX ((unsigned)(60*HZ))
 #define XFRM_MAX_QUEUE_LEN     100
 
+struct xfrm_flo {
+       struct dst_entry *dst_orig;
+       u8 flags;
+};
+
 static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
 static struct xfrm_policy_afinfo __rcu *xfrm_policy_afinfo[NPROTO]
                                                __read_mostly;
@@ -1877,13 +1882,14 @@ static int xdst_queue_output(struct sock *sk, struct sk_buff *skb)
 }
 
 static struct xfrm_dst *xfrm_create_dummy_bundle(struct net *net,
-                                                struct dst_entry *dst,
+                                                struct xfrm_flo *xflo,
                                                 const struct flowi *fl,
                                                 int num_xfrms,
                                                 u16 family)
 {
        int err;
        struct net_device *dev;
+       struct dst_entry *dst;
        struct dst_entry *dst1;
        struct xfrm_dst *xdst;
 
@@ -1891,9 +1897,12 @@ static struct xfrm_dst *xfrm_create_dummy_bundle(struct net *net,
        if (IS_ERR(xdst))
                return xdst;
 
-       if (net->xfrm.sysctl_larval_drop || num_xfrms <= 0)
+       if (!(xflo->flags & XFRM_LOOKUP_QUEUE) ||
+           net->xfrm.sysctl_larval_drop ||
+           num_xfrms <= 0)
                return xdst;
 
+       dst = xflo->dst_orig;
        dst1 = &xdst->u.dst;
        dst_hold(dst);
        xdst->route = dst;
@@ -1935,7 +1944,7 @@ static struct flow_cache_object *
 xfrm_bundle_lookup(struct net *net, const struct flowi *fl, u16 family, u8 dir,
                   struct flow_cache_object *oldflo, void *ctx)
 {
-       struct dst_entry *dst_orig = (struct dst_entry *)ctx;
+       struct xfrm_flo *xflo = (struct xfrm_flo *)ctx;
        struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX];
        struct xfrm_dst *xdst, *new_xdst;
        int num_pols = 0, num_xfrms = 0, i, err, pol_dead;
@@ -1976,7 +1985,8 @@ xfrm_bundle_lookup(struct net *net, const struct flowi *fl, u16 family, u8 dir,
                        goto make_dummy_bundle;
        }
 
-       new_xdst = xfrm_resolve_and_create_bundle(pols, num_pols, fl, family, dst_orig);
+       new_xdst = xfrm_resolve_and_create_bundle(pols, num_pols, fl, family,
+                                                 xflo->dst_orig);
        if (IS_ERR(new_xdst)) {
                err = PTR_ERR(new_xdst);
                if (err != -EAGAIN)
@@ -2010,7 +2020,7 @@ make_dummy_bundle:
        /* We found policies, but there's no bundles to instantiate:
         * either because the policy blocks, has no transformations or
         * we could not build template (no xfrm_states).*/
-       xdst = xfrm_create_dummy_bundle(net, dst_orig, fl, num_xfrms, family);
+       xdst = xfrm_create_dummy_bundle(net, xflo, fl, num_xfrms, family);
        if (IS_ERR(xdst)) {
                xfrm_pols_put(pols, num_pols);
                return ERR_CAST(xdst);
@@ -2104,13 +2114,18 @@ struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
        }
 
        if (xdst == NULL) {
+               struct xfrm_flo xflo;
+
+               xflo.dst_orig = dst_orig;
+               xflo.flags = flags;
+
                /* To accelerate a bit...  */
                if ((dst_orig->flags & DST_NOXFRM) ||
                    !net->xfrm.policy_count[XFRM_POLICY_OUT])
                        goto nopol;
 
                flo = flow_cache_lookup(net, fl, family, dir,
-                                       xfrm_bundle_lookup, dst_orig);
+                                       xfrm_bundle_lookup, &xflo);
                if (flo == NULL)
                        goto nopol;
                if (IS_ERR(flo)) {
@@ -2202,7 +2217,8 @@ struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
                                    const struct flowi *fl,
                                    struct sock *sk, int flags)
 {
-       struct dst_entry *dst = xfrm_lookup(net, dst_orig, fl, sk, flags);
+       struct dst_entry *dst = xfrm_lookup(net, dst_orig, fl, sk,
+                                           flags | XFRM_LOOKUP_QUEUE);
 
        if (IS_ERR(dst) && PTR_ERR(dst) == -EREMOTE)
                return make_blackhole(net, dst_orig->ops->family, dst_orig);
@@ -2476,7 +2492,7 @@ int __xfrm_route_forward(struct sk_buff *skb, unsigned short family)
 
        skb_dst_force(skb);
 
-       dst = xfrm_lookup(net, skb_dst(skb), &fl, NULL, 0);
+       dst = xfrm_lookup(net, skb_dst(skb), &fl, NULL, XFRM_LOOKUP_QUEUE);
        if (IS_ERR(dst)) {
                res = 0;
                dst = NULL;