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authorEric Dumazet <eric.dumazet@gmail.com>2011-07-21 21:25:58 -0700
committerDavid S. Miller <davem@davemloft.net>2011-07-21 21:25:58 -0700
commit87c48fa3b4630905f98268dde838ee43626a060c (patch)
tree1374b52ed0514682f836cfa0a6a683eb549c9613 /net/ipv6
parent21efcfa0ff27776902a8a15e810147be4d937d69 (diff)
ipv6: make fragment identifications less predictable
IPv6 fragment identification generation is way beyond what we use for IPv4 : It uses a single generator. Its not scalable and allows DOS attacks. Now inetpeer is IPv6 aware, we can use it to provide a more secure and scalable frag ident generator (per destination, instead of system wide) This patch : 1) defines a new secure_ipv6_id() helper 2) extends inet_getid() to provide 32bit results 3) extends ipv6_select_ident() with a new dest parameter Reported-by: Fernando Gont <fernando@gont.com.ar> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/ip6_output.c36
-rw-r--r--net/ipv6/udp.c2
2 files changed, 32 insertions, 6 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 8db0e4875ad8..32e5339db0c8 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -596,6 +596,31 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
return offset;
}
+void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
+{
+ static atomic_t ipv6_fragmentation_id;
+ int old, new;
+
+ if (rt) {
+ struct inet_peer *peer;
+
+ if (!rt->rt6i_peer)
+ rt6_bind_peer(rt, 1);
+ peer = rt->rt6i_peer;
+ if (peer) {
+ fhdr->identification = htonl(inet_getid(peer, 0));
+ return;
+ }
+ }
+ do {
+ old = atomic_read(&ipv6_fragmentation_id);
+ new = old + 1;
+ if (!new)
+ new = 1;
+ } while (atomic_cmpxchg(&ipv6_fragmentation_id, old, new) != old);
+ fhdr->identification = htonl(new);
+}
+
int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
{
struct sk_buff *frag;
@@ -680,7 +705,7 @@ int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
skb_reset_network_header(skb);
memcpy(skb_network_header(skb), tmp_hdr, hlen);
- ipv6_select_ident(fh);
+ ipv6_select_ident(fh, rt);
fh->nexthdr = nexthdr;
fh->reserved = 0;
fh->frag_off = htons(IP6_MF);
@@ -826,7 +851,7 @@ slow_path:
fh->nexthdr = nexthdr;
fh->reserved = 0;
if (!frag_id) {
- ipv6_select_ident(fh);
+ ipv6_select_ident(fh, rt);
frag_id = fh->identification;
} else
fh->identification = frag_id;
@@ -1076,7 +1101,8 @@ static inline int ip6_ufo_append_data(struct sock *sk,
int getfrag(void *from, char *to, int offset, int len,
int odd, struct sk_buff *skb),
void *from, int length, int hh_len, int fragheaderlen,
- int transhdrlen, int mtu,unsigned int flags)
+ int transhdrlen, int mtu,unsigned int flags,
+ struct rt6_info *rt)
{
struct sk_buff *skb;
@@ -1120,7 +1146,7 @@ static inline int ip6_ufo_append_data(struct sock *sk,
skb_shinfo(skb)->gso_size = (mtu - fragheaderlen -
sizeof(struct frag_hdr)) & ~7;
skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
- ipv6_select_ident(&fhdr);
+ ipv6_select_ident(&fhdr, rt);
skb_shinfo(skb)->ip6_frag_id = fhdr.identification;
__skb_queue_tail(&sk->sk_write_queue, skb);
@@ -1286,7 +1312,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
err = ip6_ufo_append_data(sk, getfrag, from, length,
hh_len, fragheaderlen,
- transhdrlen, mtu, flags);
+ transhdrlen, mtu, flags, rt);
if (err)
goto error;
return 0;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 328985c40883..29213b51c499 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1359,7 +1359,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, u32 features)
fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
fptr->nexthdr = nexthdr;
fptr->reserved = 0;
- ipv6_select_ident(fptr);
+ ipv6_select_ident(fptr, (struct rt6_info *)skb_dst(skb));
/* Fragment the skb. ipv6 header and the remaining fields of the
* fragment header are updated in ipv6_gso_segment()