[ovs-dev] [PATCHv2 4/9] compat: nf_defrag_ipv6: avoid/free clone operations.

Joe Stringer joe at ovn.org
Mon May 2 18:19:13 UTC 2016


Upstream commit:
    netfilter: ipv6: nf_defrag: avoid/free clone operations

    commit 6aafeef03b9d9ecf
    ("netfilter: push reasm skb through instead of original frag skbs")
    changed ipv6 defrag to not use the original skbs anymore.

    So rather than keeping the original skbs around just to discard them
    afterwards just use the original skbs directly for the fraglist of
    the newly assembled skb and remove the extra clone/free operations.

    The skb that completes the fragment queue is morphed into a the
    reassembled one instead, just like ipv4 defrag.

    openvswitch doesn't need any additional skb_morph magic anymore to deal
    with this situation so just remove that.

    A followup patch can then also remove the NF_HOOK (re)invocation in
    the ipv6 netfilter defrag hook.

    Cc: Joe Stringer <joestringer at nicira.com>
    Signed-off-by: Florian Westphal <fw at strlen.de>
    Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>

Upstream: 029f7f3b8701 ("netfilter: ipv6: nf_defrag: avoid/free clone operations")
Signed-off-by: Joe Stringer <joe at ovn.org>
---
v2: No changes.
v1: Initial Post.
---
 datapath/conntrack.c                               |  14 ---
 .../include/net/netfilter/ipv6/nf_defrag_ipv6.h    |  12 +--
 datapath/linux/compat/nf_conntrack_reasm.c         | 104 ++++++++-------------
 3 files changed, 46 insertions(+), 84 deletions(-)

diff --git a/datapath/conntrack.c b/datapath/conntrack.c
index 6cf97942ccf2..ea50ff28f01c 100644
--- a/datapath/conntrack.c
+++ b/datapath/conntrack.c
@@ -337,21 +337,7 @@ static int handle_fragments(struct net *net, struct sw_flow_key *key,
 		if (!reasm)
 			return -EINPROGRESS;
 
-		if (skb == reasm) {
-			kfree_skb(skb);
-			return -EINVAL;
-		}
-
-		/* Don't free 'skb' even though it is one of the original
-		 * fragments, as we're going to morph it into the head.
-		 */
-		skb_get(skb);
-		nf_ct_frag6_consume_orig(reasm);
-
 		key->ip.proto = ipv6_hdr(reasm)->nexthdr;
-		skb_morph(skb, reasm);
-		skb->next = reasm->next;
-		consume_skb(reasm);
 		ovs_cb.dp_cb.mru = IP6CB(skb)->frag_max_size;
 #endif /* IP frag support */
 	} else {
diff --git a/datapath/linux/compat/include/net/netfilter/ipv6/nf_defrag_ipv6.h b/datapath/linux/compat/include/net/netfilter/ipv6/nf_defrag_ipv6.h
index fe99ced37227..a3b86dab2c9c 100644
--- a/datapath/linux/compat/include/net/netfilter/ipv6/nf_defrag_ipv6.h
+++ b/datapath/linux/compat/include/net/netfilter/ipv6/nf_defrag_ipv6.h
@@ -16,17 +16,17 @@
 #define OVS_NF_DEFRAG6_BACKPORT 1
 struct sk_buff *rpl_nf_ct_frag6_gather(struct net *net, struct sk_buff *skb,
 				       u32 user);
+#define nf_ct_frag6_gather rpl_nf_ct_frag6_gather
+#endif /* HAVE_NF_CT_FRAG6_CONSUME_ORIG */
+
+#ifdef OVS_NF_DEFRAG6_BACKPORT
 int __init rpl_nf_ct_frag6_init(void);
 void rpl_nf_ct_frag6_cleanup(void);
-void rpl_nf_ct_frag6_consume_orig(struct sk_buff *skb);
-#define nf_ct_frag6_gather rpl_nf_ct_frag6_gather
-#else /* HAVE_NF_CT_FRAG6_CONSUME_ORIG */
+#else /* !OVS_NF_DEFRAG6_BACKPORT */
 static inline int __init rpl_nf_ct_frag6_init(void) { return 0; }
 static inline void rpl_nf_ct_frag6_cleanup(void) { }
-static inline void rpl_nf_ct_frag6_consume_orig(struct sk_buff *skb) { }
-#endif /* HAVE_NF_CT_FRAG6_CONSUME_ORIG */
+#endif /* OVS_NF_DEFRAG6_BACKPORT */
 #define nf_ct_frag6_init rpl_nf_ct_frag6_init
 #define nf_ct_frag6_cleanup rpl_nf_ct_frag6_cleanup
-#define nf_ct_frag6_consume_orig rpl_nf_ct_frag6_consume_orig
 
 #endif /* __NF_DEFRAG_IPV6_WRAPPER_H */
diff --git a/datapath/linux/compat/nf_conntrack_reasm.c b/datapath/linux/compat/nf_conntrack_reasm.c
index 701bd15d8efd..c6dc7ebec5b5 100644
--- a/datapath/linux/compat/nf_conntrack_reasm.c
+++ b/datapath/linux/compat/nf_conntrack_reasm.c
@@ -62,7 +62,6 @@ struct nf_ct_frag6_skb_cb
 {
 	struct inet6_skb_parm	h;
 	int			offset;
-	struct sk_buff		*orig;
 };
 
 #define NFCT_FRAG6_CB(skb)	((struct nf_ct_frag6_skb_cb*)((skb)->cb))
@@ -94,12 +93,6 @@ static unsigned int nf_hashfn(struct inet_frag_queue *q)
 	return nf_hash_frag(nq->id, &nq->saddr, &nq->daddr);
 }
 
-static void nf_skb_free(struct sk_buff *skb)
-{
-	if (NFCT_FRAG6_CB(skb)->orig)
-		kfree_skb(NFCT_FRAG6_CB(skb)->orig);
-}
-
 static void nf_ct_frag6_expire(unsigned long data)
 {
 	struct frag_queue *fq;
@@ -300,9 +293,9 @@ err:
  *	the last and the first frames arrived and all the bits are here.
  */
 static struct sk_buff *
-nf_ct_frag6_reasm(struct frag_queue *fq, struct net_device *dev)
+nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *prev,  struct net_device *dev)
 {
-	struct sk_buff *fp, *op, *head = fq->q.fragments;
+	struct sk_buff *fp, *head = fq->q.fragments;
 	int    payload_len;
 	u8 ecn;
 
@@ -353,10 +346,38 @@ nf_ct_frag6_reasm(struct frag_queue *fq, struct net_device *dev)
 		clone->csum = 0;
 		clone->ip_summed = head->ip_summed;
 
-		NFCT_FRAG6_CB(clone)->orig = NULL;
 		add_frag_mem_limit(fq->q.net, clone->truesize);
 	}
 
+	/* morph head into last received skb: prev.
+	 *
+	 * This allows callers of ipv6 conntrack defrag to continue
+	 * to use the last skb(frag) passed into the reasm engine.
+	 * The last skb frag 'silently' turns into the full reassembled skb.
+	 *
+	 * Since prev is also part of q->fragments we have to clone it first.
+	 */
+	if (head != prev) {
+		struct sk_buff *iter;
+
+		fp = skb_clone(prev, GFP_ATOMIC);
+		if (!fp)
+			goto out_oom;
+
+		fp->next = prev->next;
+		skb_queue_walk(head, iter) {
+			if (iter->next != prev)
+				continue;
+			iter->next = fp;
+			break;
+		}
+
+		skb_morph(prev, head);
+		prev->next = head->next;
+		consume_skb(head);
+		head = prev;
+	}
+
 	/* We have to remove fragment header from datagram and to relocate
 	 * header in order to calculate ICV correctly. */
 	skb_network_header(head)[fq->nhoffset] = skb_transport_header(head)[0];
@@ -397,21 +418,6 @@ nf_ct_frag6_reasm(struct frag_queue *fq, struct net_device *dev)
 	fq->q.fragments = NULL;
 	fq->q.fragments_tail = NULL;
 
-	/* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
-	fp = skb_shinfo(head)->frag_list;
-	if (fp && NFCT_FRAG6_CB(fp)->orig == NULL)
-		/* at above code, head skb is divided into two skbs. */
-		fp = fp->next;
-
-	op = NFCT_FRAG6_CB(head)->orig;
-	for (; fp; fp = fp->next) {
-		struct sk_buff *orig = NFCT_FRAG6_CB(fp)->orig;
-
-		op->next = orig;
-		op = orig;
-		NFCT_FRAG6_CB(fp)->orig = NULL;
-	}
-
 	return head;
 
 out_oversize:
@@ -490,7 +496,6 @@ find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff)
 struct sk_buff *rpl_nf_ct_frag6_gather(struct net *net, struct sk_buff *skb,
 				       u32 user)
 {
-	struct sk_buff *clone;
 	struct net_device *dev = skb->dev;
 	struct frag_hdr *fhdr;
 	struct frag_queue *fq;
@@ -508,42 +513,30 @@ struct sk_buff *rpl_nf_ct_frag6_gather(struct net *net, struct sk_buff *skb,
 	if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0)
 		return skb;
 
-	clone = skb_clone(skb, GFP_ATOMIC);
-	if (clone == NULL) {
-		pr_debug("Can't clone skb\n");
+	if (!pskb_may_pull(skb, fhoff + sizeof(*fhdr)))
 		return skb;
-	}
 
-	NFCT_FRAG6_CB(clone)->orig = skb;
-
-	if (!pskb_may_pull(clone, fhoff + sizeof(*fhdr))) {
-		pr_debug("message is too short.\n");
-		goto ret_orig;
-	}
-
-	skb_set_transport_header(clone, fhoff);
-	hdr = ipv6_hdr(clone);
-	fhdr = (struct frag_hdr *)skb_transport_header(clone);
+	skb_set_transport_header(skb, fhoff);
+	hdr = ipv6_hdr(skb);
+	fhdr = (struct frag_hdr *)skb_transport_header(skb);
 
 	fq = fq_find(net, fhdr->identification, user, &hdr->saddr, &hdr->daddr,
 		     ip6_frag_ecn(hdr));
-	if (fq == NULL) {
-		pr_debug("Can't find and can't create new queue\n");
-		goto ret_orig;
-	}
+	if (fq == NULL)
+		return skb;
 
 	spin_lock_bh(&fq->q.lock);
 
-	if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) {
+	if (nf_ct_frag6_queue(fq, skb, fhdr, nhoff) < 0) {
 		spin_unlock_bh(&fq->q.lock);
 		pr_debug("Can't insert skb to queue\n");
 		inet_frag_put(&fq->q, &nf_frags);
-		goto ret_orig;
+		return skb;
 	}
 
 	if (qp_flags(fq) == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
 	    fq->q.meat == fq->q.len) {
-		ret_skb = nf_ct_frag6_reasm(fq, dev);
+		ret_skb = nf_ct_frag6_reasm(fq, skb, dev);
 		if (ret_skb == NULL)
 			pr_debug("Can't reassemble fragmented packets\n");
 	}
@@ -551,10 +544,6 @@ struct sk_buff *rpl_nf_ct_frag6_gather(struct net *net, struct sk_buff *skb,
 
 	inet_frag_put(&fq->q, &nf_frags);
 	return ret_skb;
-
-ret_orig:
-	kfree_skb(clone);
-	return skb;
 }
 EXPORT_SYMBOL_GPL(rpl_nf_ct_frag6_gather);
 
@@ -590,18 +579,6 @@ static bool rpl_ip6_frag_match(struct inet_frag_queue *q, void *a)
 		ipv6_addr_equal(&fq->daddr, arg->dst);
 }
 
-void nf_ct_frag6_consume_orig(struct sk_buff *skb)
-{
-	struct sk_buff *s, *s2;
-
-	for (s = NFCT_FRAG6_CB(skb)->orig; s;) {
-		s2 = s->next;
-		s->next = NULL;
-		consume_skb(s);
-		s = s2;
-	}
-}
-
 static int nf_ct_net_init(struct net *net)
 {
 	nf_defrag_ipv6_enable();
@@ -626,7 +603,6 @@ int rpl_nf_ct_frag6_init(void)
 	nf_frags.hashfn = nf_hashfn;
 	nf_frags.constructor = rpl_ip6_frag_init;
 	nf_frags.destructor = NULL;
-	nf_frags.skb_free = nf_skb_free;
 	nf_frags.qsize = sizeof(struct frag_queue);
 	nf_frags.match = rpl_ip6_frag_match;
 	nf_frags.frag_expire = nf_ct_frag6_expire;
-- 
2.1.4




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