ip: generate unique IP identificator if local fragmentation is allowed

[ Upstream commit 703133de331a7a7df47f31fb9de51dc6f68a9de8 ]

If local fragmentation is allowed, then ip_select_ident() and
ip_select_ident_more() need to generate unique IDs to ensure
correct defragmentation on the peer.

For example, if IPsec (tunnel mode) has to encrypt large skbs
that have local_df bit set, then all IP fragments that belonged
to different ESP datagrams would have used the same identificator.
If one of these IP fragments would get lost or reordered, then
peer could possibly stitch together wrong IP fragments that did
not belong to the same datagram. This would lead to a packet loss
or data corruption.

Signed-off-by: Ansis Atteka <aatteka@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index 162464fe86bf7634fb9ac6c21ecd76e25beb10b6..7f10588fe6686281158982f71f032721117e578d 100644 (file)
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -281,7 +281,7 @@ static int pptp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
        nf_reset(skb);
 
        skb->ip_summed = CHECKSUM_NONE;
-       ip_select_ident(iph, &rt->dst, NULL);
+       ip_select_ident(skb, &rt->dst, NULL);
        ip_send_check(iph);
 
        ip_local_out(skb);

diff --git a/include/net/ip.h b/include/net/ip.h
index a68f838a132c522df397b9398f8f2d64646008c0..edfa59174d9a948d0c23830f7665d0fed6c03afc 100644 (file)
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -254,9 +254,11 @@ int ip_dont_fragment(struct sock *sk, struct dst_entry *dst)
 
 extern void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more);
 
-static inline void ip_select_ident(struct iphdr *iph, struct dst_entry *dst, struct sock *sk)
+static inline void ip_select_ident(struct sk_buff *skb, struct dst_entry *dst, struct sock *sk)
 {
-       if (iph->frag_off & htons(IP_DF)) {
+       struct iphdr *iph = ip_hdr(skb);
+
+       if ((iph->frag_off & htons(IP_DF)) && !skb->local_df) {
                /* This is only to work around buggy Windows95/2000
                 * VJ compression implementations.  If the ID field
                 * does not change, they drop every other packet in
@@ -268,9 +270,11 @@ static inline void ip_select_ident(struct iphdr *iph, struct dst_entry *dst, str
                __ip_select_ident(iph, dst, 0);
 }
 
-static inline void ip_select_ident_more(struct iphdr *iph, struct dst_entry *dst, struct sock *sk, int more)
+static inline void ip_select_ident_more(struct sk_buff *skb, struct dst_entry *dst, struct sock *sk, int more)
 {
-       if (iph->frag_off & htons(IP_DF)) {
+       struct iphdr *iph = ip_hdr(skb);
+
+       if ((iph->frag_off & htons(IP_DF)) && !skb->local_df) {
                if (sk && inet_sk(sk)->inet_daddr) {
                        iph->id = htons(inet_sk(sk)->inet_id);
                        inet_sk(sk)->inet_id += 1 + more;

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index d8c232794bcb4bc995f850cabf42ac7bc8eac37a..516ade1d983941ce3a69de2b490979435407bfb1 100644 (file)
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -343,7 +343,7 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size)
        pip->saddr    = fl4.saddr;
        pip->protocol = IPPROTO_IGMP;
        pip->tot_len  = 0;      /* filled in later */
-       ip_select_ident(pip, &rt->dst, NULL);
+       ip_select_ident(skb, &rt->dst, NULL);
        ((u8 *)&pip[1])[0] = IPOPT_RA;
        ((u8 *)&pip[1])[1] = 4;
        ((u8 *)&pip[1])[2] = 0;
@@ -687,7 +687,7 @@ static int igmp_send_report(struct in_device *in_dev, struct ip_mc_list *pmc,
        iph->daddr    = dst;
        iph->saddr    = fl4.saddr;
        iph->protocol = IPPROTO_IGMP;
-       ip_select_ident(iph, &rt->dst, NULL);
+       ip_select_ident(skb, &rt->dst, NULL);
        ((u8 *)&iph[1])[0] = IPOPT_RA;
        ((u8 *)&iph[1])[1] = 4;
        ((u8 *)&iph[1])[2] = 0;

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index 000e3d239d6481ed230e71c9c9033dba301694e9..33d5537881ed7b39e33199dfe978bbe5b912d706 100644 (file)
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -32,8 +32,8 @@
  *  At the moment of writing this notes identifier of IP packets is generated
  *  to be unpredictable using this code only for packets subjected
  *  (actually or potentially) to defragmentation.  I.e. DF packets less than
- *  PMTU in size uses a constant ID and do not use this code (see
- *  ip_select_ident() in include/net/ip.h).
+ *  PMTU in size when local fragmentation is disabled use a constant ID and do
+ *  not use this code (see ip_select_ident() in include/net/ip.h).
  *
  *  Route cache entries hold references to our nodes.
  *  New cache entries get references via lookup by destination IP address in

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index b663b7bda131c4d017cdeae30a65cb1557642644..ec2d430a6a55ba613e336d6b06ccc73c3f289a9b 100644 (file)
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -148,7 +148,7 @@ int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
        iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
        iph->saddr    = saddr;
        iph->protocol = sk->sk_protocol;
-       ip_select_ident(iph, &rt->dst, sk);
+       ip_select_ident(skb, &rt->dst, sk);
 
        if (opt && opt->opt.optlen) {
                iph->ihl += opt->opt.optlen>>2;
@@ -394,7 +394,7 @@ packet_routed:
                ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
        }
 
-       ip_select_ident_more(iph, &rt->dst, sk,
+       ip_select_ident_more(skb, &rt->dst, sk,
                             (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 
        skb->priority = sk->sk_priority;
@@ -1332,7 +1332,7 @@ struct sk_buff *__ip_make_skb(struct sock *sk,
        iph->ttl = ttl;
        iph->protocol = sk->sk_protocol;
        ip_copy_addrs(iph, fl4);
-       ip_select_ident(iph, &rt->dst, sk);
+       ip_select_ident(skb, &rt->dst, sk);
 
        if (opt) {
                iph->ihl += opt->optlen>>2;

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 9d9610ae78553895e9f6ccb0ea8260fa4a66ac17..2c581da1fcab2656054832755a78c12ddc9033e1 100644 (file)
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1658,7 +1658,7 @@ static void ip_encap(struct sk_buff *skb, __be32 saddr, __be32 daddr)
        iph->protocol   =       IPPROTO_IPIP;
        iph->ihl        =       5;
        iph->tot_len    =       htons(skb->len);
-       ip_select_ident(iph, skb_dst(skb), NULL);
+       ip_select_ident(skb, skb_dst(skb), NULL);
        ip_send_check(iph);
 
        memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 61e60d67adca9d24729cd06d33b02f91552b3515..6fb233772f793fce6723e5ac50dff701bb972ac2 100644 (file)
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -387,7 +387,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
                iph->check   = 0;
                iph->tot_len = htons(length);
                if (!iph->id)
-                       ip_select_ident(iph, &rt->dst, NULL);
+                       ip_select_ident(skb, &rt->dst, NULL);
 
                iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
        }

diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index eb1dd4d643f2f92d5a2385d0839d06a3424c545c..b5663c37f089ed0afe33115bcbfad2555b8d0f48 100644 (file)
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -117,7 +117,7 @@ static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 
        top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
                0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
-       ip_select_ident(top_iph, dst->child, NULL);
+       ip_select_ident(skb, dst->child, NULL);
 
        top_iph->ttl = ip4_dst_hoplimit(dst->child);
 

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 60df36d1539046d494bb7c94d7259a7fe317e221..bacc415287f6e6e3126f5d22d580d52d37c8dc7d 100644 (file)
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -865,7 +865,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
                iph->ttl        =       iph6->hop_limit;
 
        skb->ip_summed = CHECKSUM_NONE;
-       ip_select_ident(iph, skb_dst(skb), NULL);
+       ip_select_ident(skb, skb_dst(skb), NULL);
        iptunnel_xmit(skb, dev);
        return NETDEV_TX_OK;
 

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index b75ff6429a04e25d4ba8e6368173ab84a342751c..c47444e4cf8ccc9977fa0622689b4fb55799ff4b 100644 (file)
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -883,7 +883,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
        iph->daddr              =       cp->daddr.ip;
        iph->saddr              =       saddr;
        iph->ttl                =       old_iph->ttl;
-       ip_select_ident(iph, &rt->dst, NULL);
+       ip_select_ident(skb, &rt->dst, NULL);
 
        /* Another hack: avoid icmp_send in ip_fragment */
        skb->local_df = 1;