lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Thu, 20 Mar 2014 17:02:58 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Wolfgang Walter <linux@...m.de>,
	Cong Wang <xiyou.wangcong@...il.com>,
	Tom Herbert <therbert@...gle.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.13 015/149] ipv4: ipv6: better estimate tunnel header cut for correct ufo handling

3.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hannes Frederic Sowa <hannes@...essinduktion.org>

[ Upstream commit 91a48a2e85a3b70ce10ead34b4ab5347f8d215c9 ]

Currently the UFO fragmentation process does not correctly handle inner
UDP frames.

(The following tcpdumps are captured on the parent interface with ufo
disabled while tunnel has ufo enabled, 2000 bytes payload, mtu 1280,
both sit device):

IPv6:
16:39:10.031613 IP (tos 0x0, ttl 64, id 3208, offset 0, flags [DF], proto IPv6 (41), length 1300)
    192.168.122.151 > 1.1.1.1: IP6 (hlim 64, next-header Fragment (44) payload length: 1240) 2001::1 > 2001::8: frag (0x00000001:0|1232) 44883 > distinct: UDP, length 2000
16:39:10.031709 IP (tos 0x0, ttl 64, id 3209, offset 0, flags [DF], proto IPv6 (41), length 844)
    192.168.122.151 > 1.1.1.1: IP6 (hlim 64, next-header Fragment (44) payload length: 784) 2001::1 > 2001::8: frag (0x00000001:0|776) 58979 > 46366: UDP, length 5471

We can see that fragmentation header offset is not correctly updated.
(fragmentation id handling is corrected by 916e4cf46d0204 ("ipv6: reuse
ip6_frag_id from ip6_ufo_append_data")).

IPv4:
16:39:57.737761 IP (tos 0x0, ttl 64, id 3209, offset 0, flags [DF], proto IPIP (4), length 1296)
    192.168.122.151 > 1.1.1.1: IP (tos 0x0, ttl 64, id 57034, offset 0, flags [none], proto UDP (17), length 1276)
    192.168.99.1.35961 > 192.168.99.2.distinct: UDP, length 2000
16:39:57.738028 IP (tos 0x0, ttl 64, id 3210, offset 0, flags [DF], proto IPIP (4), length 792)
    192.168.122.151 > 1.1.1.1: IP (tos 0x0, ttl 64, id 57035, offset 0, flags [none], proto UDP (17), length 772)
    192.168.99.1.13531 > 192.168.99.2.20653: UDP, length 51109

In this case fragmentation id is incremented and offset is not updated.

First, I aligned inet_gso_segment and ipv6_gso_segment:
* align naming of flags
* ipv6_gso_segment: setting skb->encapsulation is unnecessary, as we
  always ensure that the state of this flag is left untouched when
  returning from upper gso segmenation function
* ipv6_gso_segment: move skb_reset_inner_headers below updating the
  fragmentation header data, we don't care for updating fragmentation
  header data
* remove currently unneeded comment indicating skb->encapsulation might
  get changed by upper gso_segment callback (gre and udp-tunnel reset
  encapsulation after segmentation on each fragment)

If we encounter an IPIP or SIT gso skb we now check for the protocol ==
IPPROTO_UDP and that we at least have already traversed another ip(6)
protocol header.

The reason why we have to special case GSO_IPIP and GSO_SIT is that
we reset skb->encapsulation to 0 while skb_mac_gso_segment the inner
protocol of GSO_UDP_TUNNEL or GSO_GRE packets.

Reported-by: Wolfgang Walter <linux@...m.de>
Cc: Cong Wang <xiyou.wangcong@...il.com>
Cc: Tom Herbert <therbert@...gle.com>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/af_inet.c     |    7 +++++--
 net/ipv6/ip6_offload.c |   20 ++++++++++++--------
 2 files changed, 17 insertions(+), 10 deletions(-)

--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1299,8 +1299,11 @@ static struct sk_buff *inet_gso_segment(
 
 	segs = ERR_PTR(-EPROTONOSUPPORT);
 
-	/* Note : following gso_segment() might change skb->encapsulation */
-	udpfrag = !skb->encapsulation && proto == IPPROTO_UDP;
+	if (skb->encapsulation &&
+	    skb_shinfo(skb)->gso_type & (SKB_GSO_SIT|SKB_GSO_IPIP))
+		udpfrag = proto == IPPROTO_UDP && encap;
+	else
+		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
 
 	ops = rcu_dereference(inet_offloads[proto]);
 	if (likely(ops && ops->callbacks.gso_segment))
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -89,7 +89,7 @@ static struct sk_buff *ipv6_gso_segment(
 	unsigned int unfrag_ip6hlen;
 	u8 *prevhdr;
 	int offset = 0;
-	bool tunnel;
+	bool encap, udpfrag;
 	int nhoff;
 
 	if (unlikely(skb_shinfo(skb)->gso_type &
@@ -110,8 +110,8 @@ static struct sk_buff *ipv6_gso_segment(
 	if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 		goto out;
 
-	tunnel = SKB_GSO_CB(skb)->encap_level > 0;
-	if (tunnel)
+	encap = SKB_GSO_CB(skb)->encap_level > 0;
+	if (encap)
 		features = skb->dev->hw_enc_features & netif_skb_features(skb);
 	SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);
 
@@ -121,6 +121,12 @@ static struct sk_buff *ipv6_gso_segment(
 
 	proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
 
+	if (skb->encapsulation &&
+	    skb_shinfo(skb)->gso_type & (SKB_GSO_SIT|SKB_GSO_IPIP))
+		udpfrag = proto == IPPROTO_UDP && encap;
+	else
+		udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
+
 	ops = rcu_dereference(inet6_offloads[proto]);
 	if (likely(ops && ops->callbacks.gso_segment)) {
 		skb_reset_transport_header(skb);
@@ -133,13 +139,9 @@ static struct sk_buff *ipv6_gso_segment(
 	for (skb = segs; skb; skb = skb->next) {
 		ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
 		ipv6h->payload_len = htons(skb->len - nhoff - sizeof(*ipv6h));
-		if (tunnel) {
-			skb_reset_inner_headers(skb);
-			skb->encapsulation = 1;
-		}
 		skb->network_header = (u8 *)ipv6h - skb->head;
 
-		if (!tunnel && proto == IPPROTO_UDP) {
+		if (udpfrag) {
 			unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
 			fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen);
 			fptr->frag_off = htons(offset);
@@ -148,6 +150,8 @@ static struct sk_buff *ipv6_gso_segment(
 			offset += (ntohs(ipv6h->payload_len) -
 				   sizeof(struct frag_hdr));
 		}
+		if (encap)
+			skb_reset_inner_headers(skb);
 	}
 
 out:


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists