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Message-Id: <20190529112539.2126-3-pablo@netfilter.org>
Date: Wed, 29 May 2019 13:25:32 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org,
nikolay@...ulusnetworks.com, roopa@...ulusnetworks.com
Subject: [PATCH net-next,v3 2/9] net: ipv6: add skbuff fraglist splitter
This patch adds the skbuff fraglist split iterator. This API provides an
iterator to transform the fraglist into single skbuff objects, it
consists of:
* ip6_fraglist_init(), that initializes the internal state of the
fraglist iterator.
* ip6_fraglist_prepare(), that restores the IPv6 header on the fragment.
* ip6_fraglist_next(), that retrieves the fragment from the fraglist and
updates the internal state of the iterator to point to the next
fragment in the fraglist.
The ip6_fraglist_iter object stores the internal state of the iterator.
This code has been extracted from ip6_fragment(). Symbols are also
exported to allow to reuse this iterator from the bridge codepath to
build its own refragmentation routine by reusing the existing codebase.
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/net/ipv6.h | 25 ++++++++++
net/ipv6/ip6_output.c | 132 +++++++++++++++++++++++++++++---------------------
2 files changed, 102 insertions(+), 55 deletions(-)
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index daf80863d3a5..acefbc718abe 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -154,6 +154,31 @@ struct frag_hdr {
#define IP6_MF 0x0001
#define IP6_OFFSET 0xFFF8
+struct ip6_fraglist_iter {
+ struct ipv6hdr *tmp_hdr;
+ struct sk_buff *frag_list;
+ struct sk_buff *frag;
+ int offset;
+ unsigned int hlen;
+ __be32 frag_id;
+ u8 nexthdr;
+};
+
+int ip6_fraglist_init(struct sk_buff *skb, unsigned int hlen, u8 *prevhdr,
+ u8 nexthdr, __be32 frag_id,
+ struct ip6_fraglist_iter *iter);
+void ip6_fraglist_prepare(struct sk_buff *skb, struct ip6_fraglist_iter *iter);
+
+static inline struct sk_buff *ip6_fraglist_next(struct ip6_fraglist_iter *iter)
+{
+ struct sk_buff *skb = iter->frag;
+
+ iter->frag = skb->next;
+ skb_mark_not_on_list(skb);
+
+ return skb;
+}
+
#define IP6_REPLY_MARK(net, mark) \
((net)->ipv6.sysctl.fwmark_reflect ? (mark) : 0)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index adef2236abe2..2567b22a888a 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -592,6 +592,73 @@ static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
skb_copy_secmark(to, from);
}
+int ip6_fraglist_init(struct sk_buff *skb, unsigned int hlen, u8 *prevhdr,
+ u8 nexthdr, __be32 frag_id,
+ struct ip6_fraglist_iter *iter)
+{
+ unsigned int first_len;
+ struct frag_hdr *fh;
+
+ /* BUILD HEADER */
+ *prevhdr = NEXTHDR_FRAGMENT;
+ iter->tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
+ if (!iter->tmp_hdr)
+ return -ENOMEM;
+
+ iter->frag_list = skb_shinfo(skb)->frag_list;
+ iter->frag = iter->frag_list;
+ skb_frag_list_init(skb);
+
+ iter->offset = 0;
+ iter->hlen = hlen;
+ iter->frag_id = frag_id;
+ iter->nexthdr = nexthdr;
+
+ __skb_pull(skb, hlen);
+ fh = __skb_push(skb, sizeof(struct frag_hdr));
+ __skb_push(skb, hlen);
+ skb_reset_network_header(skb);
+ memcpy(skb_network_header(skb), iter->tmp_hdr, hlen);
+
+ fh->nexthdr = nexthdr;
+ fh->reserved = 0;
+ fh->frag_off = htons(IP6_MF);
+ fh->identification = frag_id;
+
+ first_len = skb_pagelen(skb);
+ skb->data_len = first_len - skb_headlen(skb);
+ skb->len = first_len;
+ ipv6_hdr(skb)->payload_len = htons(first_len - sizeof(struct ipv6hdr));
+
+ return 0;
+}
+EXPORT_SYMBOL(ip6_fraglist_init);
+
+void ip6_fraglist_prepare(struct sk_buff *skb,
+ struct ip6_fraglist_iter *iter)
+{
+ struct sk_buff *frag = iter->frag;
+ unsigned int hlen = iter->hlen;
+ struct frag_hdr *fh;
+
+ frag->ip_summed = CHECKSUM_NONE;
+ skb_reset_transport_header(frag);
+ fh = __skb_push(frag, sizeof(struct frag_hdr));
+ __skb_push(frag, hlen);
+ skb_reset_network_header(frag);
+ memcpy(skb_network_header(frag), iter->tmp_hdr, hlen);
+ iter->offset += skb->len - hlen - sizeof(struct frag_hdr);
+ fh->nexthdr = iter->nexthdr;
+ fh->reserved = 0;
+ fh->frag_off = htons(iter->offset);
+ if (frag->next)
+ fh->frag_off |= htons(IP6_MF);
+ fh->identification = iter->frag_id;
+ ipv6_hdr(frag)->payload_len = htons(frag->len - sizeof(struct ipv6hdr));
+ ip6_copy_metadata(frag, skb);
+}
+EXPORT_SYMBOL(ip6_fraglist_prepare);
+
int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
int (*output)(struct net *, struct sock *, struct sk_buff *))
{
@@ -599,7 +666,6 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
inet6_sk(skb->sk) : NULL;
- struct ipv6hdr *tmp_hdr;
struct frag_hdr *fh;
unsigned int mtu, hlen, left, len, nexthdr_offset;
int hroom, troom;
@@ -651,6 +717,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
hroom = LL_RESERVED_SPACE(rt->dst.dev);
if (skb_has_frag_list(skb)) {
unsigned int first_len = skb_pagelen(skb);
+ struct ip6_fraglist_iter iter;
struct sk_buff *frag2;
if (first_len - hlen > mtu ||
@@ -678,74 +745,29 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
skb->truesize -= frag->truesize;
}
- err = 0;
- offset = 0;
- /* BUILD HEADER */
-
- *prevhdr = NEXTHDR_FRAGMENT;
- tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
- if (!tmp_hdr) {
- err = -ENOMEM;
+ err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id,
+ &iter);
+ if (err < 0)
goto fail;
- }
- frag = skb_shinfo(skb)->frag_list;
- skb_frag_list_init(skb);
-
- __skb_pull(skb, hlen);
- fh = __skb_push(skb, sizeof(struct frag_hdr));
- __skb_push(skb, hlen);
- skb_reset_network_header(skb);
- memcpy(skb_network_header(skb), tmp_hdr, hlen);
-
- fh->nexthdr = nexthdr;
- fh->reserved = 0;
- fh->frag_off = htons(IP6_MF);
- fh->identification = frag_id;
-
- first_len = skb_pagelen(skb);
- skb->data_len = first_len - skb_headlen(skb);
- skb->len = first_len;
- ipv6_hdr(skb)->payload_len = htons(first_len -
- sizeof(struct ipv6hdr));
for (;;) {
/* Prepare header of the next frame,
* before previous one went down. */
- if (frag) {
- frag->ip_summed = CHECKSUM_NONE;
- skb_reset_transport_header(frag);
- fh = __skb_push(frag, sizeof(struct frag_hdr));
- __skb_push(frag, hlen);
- skb_reset_network_header(frag);
- memcpy(skb_network_header(frag), tmp_hdr,
- hlen);
- offset += skb->len - hlen - sizeof(struct frag_hdr);
- fh->nexthdr = nexthdr;
- fh->reserved = 0;
- fh->frag_off = htons(offset);
- if (frag->next)
- fh->frag_off |= htons(IP6_MF);
- fh->identification = frag_id;
- ipv6_hdr(frag)->payload_len =
- htons(frag->len -
- sizeof(struct ipv6hdr));
- ip6_copy_metadata(frag, skb);
- }
+ if (iter.frag)
+ ip6_fraglist_prepare(skb, &iter);
err = output(net, sk, skb);
if (!err)
IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
IPSTATS_MIB_FRAGCREATES);
- if (err || !frag)
+ if (err || !iter.frag)
break;
- skb = frag;
- frag = skb->next;
- skb_mark_not_on_list(skb);
+ skb = ip6_fraglist_next(&iter);
}
- kfree(tmp_hdr);
+ kfree(iter.tmp_hdr);
if (err == 0) {
IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
@@ -753,7 +775,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
return 0;
}
- kfree_skb_list(frag);
+ kfree_skb_list(iter.frag_list);
IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
IPSTATS_MIB_FRAGFAILS);
--
2.11.0
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