From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754891Ab3FDWpY (ORCPT ); Tue, 4 Jun 2013 18:45:24 -0400 Received: from 1wt.eu ([62.212.114.60]:35952 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752014Ab3FDWpV (ORCPT ); Tue, 4 Jun 2013 18:45:21 -0400 Message-Id: <20130604172137.263956682@1wt.eu> User-Agent: quilt/0.48-1 Date: Tue, 04 Jun 2013 19:24:18 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Dumazet , "David S. Miller" , Greg Kroah-Hartman , Ben Hutchings , Willy Tarreau Subject: [ 168/184] ipv6: make fragment identifications less predictable In-Reply-To: <58df134a4b98edf5b0073e2e1e988fe6@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Backport of upstream commit 87c48fa3b4630905f98268dde838ee43626a060c ] Fernando Gont reported current IPv6 fragment identification generation was not secure, because using a very predictable system-wide generator, allowing various attacks. IPv4 uses inetpeer cache to address this problem and to get good performance. We'll use this mechanism when IPv6 inetpeer is stable enough in linux-3.1 For the time being, we use jhash on destination address to provide less predictable identifications. Also remove a spinlock and use cmpxchg() to get better SMP performance. Reported-by: Fernando Gont Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman [bwh: Backport further to 2.6.32] Signed-off-by: Ben Hutchings Signed-off-by: Willy Tarreau --- include/net/ipv6.h | 12 +----------- include/net/transp_v6.h | 2 ++ net/ipv6/af_inet6.c | 2 ++ net/ipv6/ip6_output.c | 40 +++++++++++++++++++++++++++++++++++----- net/ipv6/udp.c | 2 +- 5 files changed, 41 insertions(+), 17 deletions(-) diff --git a/include/net/ipv6.h b/include/net/ipv6.h index 639bbf0..52d86da 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -449,17 +449,7 @@ static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_add return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr)); } -static __inline__ void ipv6_select_ident(struct frag_hdr *fhdr) -{ - static u32 ipv6_fragmentation_id = 1; - static DEFINE_SPINLOCK(ip6_id_lock); - - spin_lock_bh(&ip6_id_lock); - fhdr->identification = htonl(ipv6_fragmentation_id); - if (++ipv6_fragmentation_id == 0) - ipv6_fragmentation_id = 1; - spin_unlock_bh(&ip6_id_lock); -} +extern void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt); /* * Prototypes exported by ipv6 diff --git a/include/net/transp_v6.h b/include/net/transp_v6.h index d65381c..8beefe1 100644 --- a/include/net/transp_v6.h +++ b/include/net/transp_v6.h @@ -16,6 +16,8 @@ extern struct proto tcpv6_prot; struct flowi; +extern void initialize_hashidentrnd(void); + /* extention headers */ extern int ipv6_exthdrs_init(void); extern void ipv6_exthdrs_exit(void); diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index e127a32..835590d 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -1073,6 +1073,8 @@ static int __init inet6_init(void) goto out; } + initialize_hashidentrnd(); + err = proto_register(&tcpv6_prot, 1); if (err) goto out; diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 9ad5792..6ba0fe2 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -604,6 +604,35 @@ int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr) return offset; } +static u32 hashidentrnd __read_mostly; +#define FID_HASH_SZ 16 +static u32 ipv6_fragmentation_id[FID_HASH_SZ]; + +void __init initialize_hashidentrnd(void) +{ + get_random_bytes(&hashidentrnd, sizeof(hashidentrnd)); +} + +static u32 __ipv6_select_ident(const struct in6_addr *addr) +{ + u32 newid, oldid, hash = jhash2((u32 *)addr, 4, hashidentrnd); + u32 *pid = &ipv6_fragmentation_id[hash % FID_HASH_SZ]; + + do { + oldid = *pid; + newid = oldid + 1; + if (!(hash + newid)) + newid++; + } while (cmpxchg(pid, oldid, newid) != oldid); + + return hash + newid; +} + +void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) +{ + fhdr->identification = htonl(__ipv6_select_ident(&rt->rt6i_dst.addr)); +} + static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) { struct sk_buff *frag; @@ -689,7 +718,7 @@ static 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); @@ -835,7 +864,7 @@ 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; @@ -1039,7 +1068,8 @@ 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; @@ -1084,7 +1114,7 @@ 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); @@ -1233,7 +1263,7 @@ 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); + flags, rt); if (err) goto error; return 0; diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 9cc6289..d8c0374 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1162,7 +1162,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, int 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() -- 1.7.12.2.21.g234cd45.dirty