From patchwork Mon Oct 10 13:43:46 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sabrina Dubroca X-Patchwork-Id: 680412 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3st1Z521ktz9ryn for ; Tue, 11 Oct 2016 00:44:13 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752354AbcJJNoJ (ORCPT ); Mon, 10 Oct 2016 09:44:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32836 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751392AbcJJNoI (ORCPT ); Mon, 10 Oct 2016 09:44:08 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C3C3CE034D; Mon, 10 Oct 2016 13:44:07 +0000 (UTC) Received: from localhost.localdomain (ovpn-204-54.brq.redhat.com [10.40.204.54]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u9ADi5ph012768; Mon, 10 Oct 2016 09:44:06 -0400 From: Sabrina Dubroca To: netdev@vger.kernel.org Cc: Hannes Frederic Sowa , Jiri Benc , Sabrina Dubroca Subject: [PATCH net] net: add recursion limit to GRO Date: Mon, 10 Oct 2016 15:43:46 +0200 Message-Id: <8fb8ec65c178b4d37951c4538dedc880eef068d4.1476106975.git.sd@queasysnail.net> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Mon, 10 Oct 2016 13:44:07 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently, GRO can do unlimited recursion through the gro_receive handlers. This was fixed for tunneling protocols by limiting tunnel GRO to one level with encap_mark, but both VLAN and TEB still have this problem. Thus, the kernel is vulnerable to a stack overflow, if we receive a packet composed entirely of VLAN headers. This patch adds a recursion counter to the GRO layer to prevent stack overflow. When a gro_receive function hits the recursion limit, GRO is aborted for this skb and it is processed normally. Thanks to Vladimír Beneš for the initial bug report. Fixes: CVE-2016-7039 Fixes: 9b174d88c257 ("net: Add Transparent Ethernet Bridging GRO support.") Fixes: 66e5133f19e9 ("vlan: Add GRO support for non hardware accelerated vlan") Signed-off-by: Sabrina Dubroca Reviewed-by: Jiri Benc Acked-by: Hannes Frederic Sowa --- drivers/net/geneve.c | 2 +- drivers/net/vxlan.c | 2 +- include/linux/netdevice.h | 24 +++++++++++++++++++++++- net/8021q/vlan.c | 2 +- net/core/dev.c | 1 + net/ethernet/eth.c | 2 +- net/ipv4/af_inet.c | 2 +- net/ipv4/fou.c | 4 ++-- net/ipv4/gre_offload.c | 2 +- net/ipv4/udp_offload.c | 8 +++++++- net/ipv6/ip6_offload.c | 2 +- 11 files changed, 40 insertions(+), 11 deletions(-) diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c index 3c20e87bb761..16af1ce99233 100644 --- a/drivers/net/geneve.c +++ b/drivers/net/geneve.c @@ -453,7 +453,7 @@ static struct sk_buff **geneve_gro_receive(struct sock *sk, skb_gro_pull(skb, gh_len); skb_gro_postpull_rcsum(skb, gh, gh_len); - pp = ptype->callbacks.gro_receive(head, skb); + pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb); flush = 0; out_unlock: diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index e7d16687538b..c1639a3e95a4 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -583,7 +583,7 @@ static struct sk_buff **vxlan_gro_receive(struct sock *sk, } } - pp = eth_gro_receive(head, skb); + pp = call_gro_receive(eth_gro_receive, head, skb); flush = 0; out: diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 136ae6bbe81e..11a7218c3661 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2169,7 +2169,10 @@ struct napi_gro_cb { /* Used to determine if flush_id can be ignored */ u8 is_atomic:1; - /* 5 bit hole */ + /* Number of gro_receive callbacks this packet already went through */ + u8 recursion_counter:4; + + /* 1 bit hole */ /* used to support CHECKSUM_COMPLETE for tunneling protocols */ __wsum csum; @@ -2180,6 +2183,25 @@ struct napi_gro_cb { #define NAPI_GRO_CB(skb) ((struct napi_gro_cb *)(skb)->cb) +#define GRO_RECURSION_LIMIT 15 +static inline int gro_recursion_inc_test(struct sk_buff *skb) +{ + return ++NAPI_GRO_CB(skb)->recursion_counter == GRO_RECURSION_LIMIT; +} + +typedef struct sk_buff **(*gro_receive_t)(struct sk_buff **, struct sk_buff *); +static inline struct sk_buff **call_gro_receive(gro_receive_t cb, + struct sk_buff **head, + struct sk_buff *skb) +{ + if (gro_recursion_inc_test(skb)) { + NAPI_GRO_CB(skb)->flush |= 1; + return NULL; + } + + return cb(head, skb); +} + struct packet_type { __be16 type; /* This is really htons(ether_type). */ struct net_device *dev; /* NULL is wildcarded here */ diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c index 8de138d3306b..f2531ad66b68 100644 --- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -664,7 +664,7 @@ static struct sk_buff **vlan_gro_receive(struct sk_buff **head, skb_gro_pull(skb, sizeof(*vhdr)); skb_gro_postpull_rcsum(skb, vhdr, sizeof(*vhdr)); - pp = ptype->callbacks.gro_receive(head, skb); + pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb); out_unlock: rcu_read_unlock(); diff --git a/net/core/dev.c b/net/core/dev.c index f1fe26f66458..f7cd4b8b035d 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4511,6 +4511,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff NAPI_GRO_CB(skb)->flush = 0; NAPI_GRO_CB(skb)->free = 0; NAPI_GRO_CB(skb)->encap_mark = 0; + NAPI_GRO_CB(skb)->recursion_counter = 0; NAPI_GRO_CB(skb)->is_fou = 0; NAPI_GRO_CB(skb)->is_atomic = 1; NAPI_GRO_CB(skb)->gro_remcsum_start = 0; diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c index 66dff5e3d772..02acfff36028 100644 --- a/net/ethernet/eth.c +++ b/net/ethernet/eth.c @@ -439,7 +439,7 @@ struct sk_buff **eth_gro_receive(struct sk_buff **head, skb_gro_pull(skb, sizeof(*eh)); skb_gro_postpull_rcsum(skb, eh, sizeof(*eh)); - pp = ptype->callbacks.gro_receive(head, skb); + pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb); out_unlock: rcu_read_unlock(); diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 1effc986739e..9648c97e541f 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1391,7 +1391,7 @@ struct sk_buff **inet_gro_receive(struct sk_buff **head, struct sk_buff *skb) skb_gro_pull(skb, sizeof(*iph)); skb_set_transport_header(skb, skb_gro_offset(skb)); - pp = ops->callbacks.gro_receive(head, skb); + pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); out_unlock: rcu_read_unlock(); diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c index cf50f7e2b012..030d1531e897 100644 --- a/net/ipv4/fou.c +++ b/net/ipv4/fou.c @@ -249,7 +249,7 @@ static struct sk_buff **fou_gro_receive(struct sock *sk, if (!ops || !ops->callbacks.gro_receive) goto out_unlock; - pp = ops->callbacks.gro_receive(head, skb); + pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); out_unlock: rcu_read_unlock(); @@ -441,7 +441,7 @@ static struct sk_buff **gue_gro_receive(struct sock *sk, if (WARN_ON_ONCE(!ops || !ops->callbacks.gro_receive)) goto out_unlock; - pp = ops->callbacks.gro_receive(head, skb); + pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); flush = 0; out_unlock: diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c index 96e0efecefa6..d5cac99170b1 100644 --- a/net/ipv4/gre_offload.c +++ b/net/ipv4/gre_offload.c @@ -229,7 +229,7 @@ static struct sk_buff **gre_gro_receive(struct sk_buff **head, /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/ skb_gro_postpull_rcsum(skb, greh, grehlen); - pp = ptype->callbacks.gro_receive(head, skb); + pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb); flush = 0; out_unlock: diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index f9333c963607..7b5879bcd08b 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -295,7 +295,13 @@ struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb, skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */ skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr)); - pp = udp_sk(sk)->gro_receive(sk, head, skb); + + if (gro_recursion_inc_test(skb)) { + flush = 1; + pp = NULL; + } else { + pp = udp_sk(sk)->gro_receive(sk, head, skb); + } out_unlock: rcu_read_unlock(); diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c index e7bfd55899a3..1fcf61f1cbc3 100644 --- a/net/ipv6/ip6_offload.c +++ b/net/ipv6/ip6_offload.c @@ -246,7 +246,7 @@ static struct sk_buff **ipv6_gro_receive(struct sk_buff **head, skb_gro_postpull_rcsum(skb, iph, nlen); - pp = ops->callbacks.gro_receive(head, skb); + pp = call_gro_receive(ops->callbacks.gro_receive, head, skb); out_unlock: rcu_read_unlock();