diff options
| author | Eric Dumazet | 2011-07-21 21:25:58 -0700 |
|---|---|---|
| committer | David S. Miller | 2011-07-21 21:25:58 -0700 |
| commit | 87c48fa3b4630905f98268dde838ee43626a060c (patch) | |
| tree | 1374b52ed0514682f836cfa0a6a683eb549c9613 /net/ipv6 | |
| parent | 21efcfa0ff27776902a8a15e810147be4d937d69 (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.c | 36 | ||||
| -rw-r--r-- | net/ipv6/udp.c | 2 |
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() |