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Message-Id: <20181230222436.37920-1-willemdebruijn.kernel@gmail.com>
Date: Sun, 30 Dec 2018 17:24:36 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
xiyou.wangcong@...il.com, Willem de Bruijn <willemb@...gle.com>,
syzbot <syzkaller@...glegroups.com>
Subject: [PATCH net] ip: validate header length on virtual device xmit
From: Willem de Bruijn <willemb@...gle.com>
KMSAN detected read beyond end of buffer in vti and sit devices when
passing truncated packets with PF_PACKET. The issue affects additional
ip tunnel devices.
Extend commit 76c0ddd8c3a6 ("ip6_tunnel: be careful when accessing the
inner header") and commit ccfec9e5cb2d ("ip_tunnel: be careful when
accessing the inner header").
Move the check to a separate helper and call at the start of each
ndo_start_xmit function in net/ipv4 and net/ipv6.
Minor changes:
- convert dev_kfree_skb to kfree_skb on error path,
as dev_kfree_skb calls consume_skb which is not for error paths.
- use pskb_network_may_pull even though that is pedantic here,
as the same as pskb_may_pull for devices without llheaders.
- do not cache ipv6 hdrs if used only once
(unsafe across pskb_may_pull, was more relevant to earlier patch)
Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
This probably exist since the start of these devices, so no single
Fixes tag. If easier for stable, I can split into per device commits.
---
include/net/ip_tunnels.h | 20 ++++++++++++++++++++
net/ipv4/ip_gre.c | 9 +++++++++
net/ipv4/ip_tunnel.c | 9 ---------
net/ipv4/ip_vti.c | 12 +++++++++---
net/ipv6/ip6_gre.c | 10 +++++++---
net/ipv6/ip6_tunnel.c | 10 +++-------
net/ipv6/ip6_vti.c | 8 ++++----
net/ipv6/ip6mr.c | 17 +++++++++++------
net/ipv6/sit.c | 3 +++
9 files changed, 66 insertions(+), 32 deletions(-)
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index cbcf35ce1b14..34f019650941 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -308,6 +308,26 @@ int ip_tunnel_encap_del_ops(const struct ip_tunnel_encap_ops *op,
int ip_tunnel_encap_setup(struct ip_tunnel *t,
struct ip_tunnel_encap *ipencap);
+static inline bool pskb_inet_may_pull(struct sk_buff *skb)
+{
+ int nhlen;
+
+ switch (skb->protocol) {
+#if IS_ENABLED(CONFIG_IPV6)
+ case htons(ETH_P_IPV6):
+ nhlen = sizeof(struct ipv6hdr);
+ break;
+#endif
+ case htons(ETH_P_IP):
+ nhlen = sizeof(struct iphdr);
+ break;
+ default:
+ nhlen = 0;
+ }
+
+ return pskb_network_may_pull(skb, nhlen);
+}
+
static inline int ip_encap_hlen(struct ip_tunnel_encap *e)
{
const struct ip_tunnel_encap_ops *ops;
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index c7a7bd58a23c..d1d09f3e5f9e 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -676,6 +676,9 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
struct ip_tunnel *tunnel = netdev_priv(dev);
const struct iphdr *tnl_params;
+ if (!pskb_inet_may_pull(skb))
+ goto free_skb;
+
if (tunnel->collect_md) {
gre_fb_xmit(skb, dev, skb->protocol);
return NETDEV_TX_OK;
@@ -719,6 +722,9 @@ static netdev_tx_t erspan_xmit(struct sk_buff *skb,
struct ip_tunnel *tunnel = netdev_priv(dev);
bool truncate = false;
+ if (!pskb_inet_may_pull(skb))
+ goto free_skb;
+
if (tunnel->collect_md) {
erspan_fb_xmit(skb, dev, skb->protocol);
return NETDEV_TX_OK;
@@ -762,6 +768,9 @@ static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
{
struct ip_tunnel *tunnel = netdev_priv(dev);
+ if (!pskb_inet_may_pull(skb))
+ goto free_skb;
+
if (tunnel->collect_md) {
gre_fb_xmit(skb, dev, htons(ETH_P_TEB));
return NETDEV_TX_OK;
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 284a22154b4e..c4f5602308ed 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -627,7 +627,6 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
const struct iphdr *tnl_params, u8 protocol)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
- unsigned int inner_nhdr_len = 0;
const struct iphdr *inner_iph;
struct flowi4 fl4;
u8 tos, ttl;
@@ -637,14 +636,6 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
__be32 dst;
bool connected;
- /* ensure we can access the inner net header, for several users below */
- if (skb->protocol == htons(ETH_P_IP))
- inner_nhdr_len = sizeof(struct iphdr);
- else if (skb->protocol == htons(ETH_P_IPV6))
- inner_nhdr_len = sizeof(struct ipv6hdr);
- if (unlikely(!pskb_may_pull(skb, inner_nhdr_len)))
- goto tx_error;
-
inner_iph = (const struct iphdr *)skb_inner_network_header(skb);
connected = (tunnel->parms.iph.daddr != 0);
diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index de31b302d69c..d7b43e700023 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -241,6 +241,9 @@ static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
struct ip_tunnel *tunnel = netdev_priv(dev);
struct flowi fl;
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
+
memset(&fl, 0, sizeof(fl));
switch (skb->protocol) {
@@ -253,15 +256,18 @@ static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
break;
default:
- dev->stats.tx_errors++;
- dev_kfree_skb(skb);
- return NETDEV_TX_OK;
+ goto tx_err;
}
/* override mark with tunnel output key */
fl.flowi_mark = be32_to_cpu(tunnel->parms.o_key);
return vti_xmit(skb, dev, &fl);
+
+tx_err:
+ dev->stats.tx_errors++;
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
}
static int vti4_err(struct sk_buff *skb, u32 info)
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 229e55c99021..09d0826742f8 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -881,6 +881,9 @@ static netdev_tx_t ip6gre_tunnel_xmit(struct sk_buff *skb,
struct net_device_stats *stats = &t->dev->stats;
int ret;
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
+
if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr))
goto tx_err;
@@ -923,6 +926,9 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
int nhoff;
int thoff;
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
+
if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr))
goto tx_err;
@@ -995,8 +1001,6 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
goto tx_err;
}
} else {
- struct ipv6hdr *ipv6h = ipv6_hdr(skb);
-
switch (skb->protocol) {
case htons(ETH_P_IP):
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
@@ -1004,7 +1008,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
&dsfield, &encap_limit);
break;
case htons(ETH_P_IPV6):
- if (ipv6_addr_equal(&t->parms.raddr, &ipv6h->saddr))
+ if (ipv6_addr_equal(&t->parms.raddr, &ipv6_hdr(skb)->saddr))
goto tx_err;
if (prepare_ip6gre_xmit_ipv6(skb, dev, &fl6,
&dsfield, &encap_limit))
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 99179b9c8384..0c6403cf8b52 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1243,10 +1243,6 @@ ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
u8 tproto;
int err;
- /* ensure we can access the full inner ip header */
- if (!pskb_may_pull(skb, sizeof(struct iphdr)))
- return -1;
-
iph = ip_hdr(skb);
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
@@ -1321,9 +1317,6 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
u8 tproto;
int err;
- if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
- return -1;
-
ipv6h = ipv6_hdr(skb);
tproto = READ_ONCE(t->parms.proto);
if ((tproto != IPPROTO_IPV6 && tproto != 0) ||
@@ -1405,6 +1398,9 @@ ip6_tnl_start_xmit(struct sk_buff *skb, struct net_device *dev)
struct net_device_stats *stats = &t->dev->stats;
int ret;
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
+
switch (skb->protocol) {
case htons(ETH_P_IP):
ret = ip4ip6_tnl_xmit(skb, dev);
diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 706fe42e4928..8b6eefff2f7e 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -522,18 +522,18 @@ vti6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct ip6_tnl *t = netdev_priv(dev);
struct net_device_stats *stats = &t->dev->stats;
- struct ipv6hdr *ipv6h;
struct flowi fl;
int ret;
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
+
memset(&fl, 0, sizeof(fl));
switch (skb->protocol) {
case htons(ETH_P_IPV6):
- ipv6h = ipv6_hdr(skb);
-
if ((t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) ||
- vti6_addr_conflict(t, ipv6h))
+ vti6_addr_conflict(t, ipv6_hdr(skb)))
goto tx_err;
xfrm_decode_session(skb, &fl, AF_INET6);
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 8276f1224f16..30337b38274b 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -51,6 +51,7 @@
#include <linux/export.h>
#include <net/ip6_checksum.h>
#include <linux/netconf.h>
+#include <net/ip_tunnels.h>
#include <linux/nospec.h>
@@ -599,13 +600,12 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
.flowi6_iif = skb->skb_iif ? : LOOPBACK_IFINDEX,
.flowi6_mark = skb->mark,
};
- int err;
- err = ip6mr_fib_lookup(net, &fl6, &mrt);
- if (err < 0) {
- kfree_skb(skb);
- return err;
- }
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
+
+ if (ip6mr_fib_lookup(net, &fl6, &mrt) < 0)
+ goto tx_err;
read_lock(&mrt_lock);
dev->stats.tx_bytes += skb->len;
@@ -614,6 +614,11 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
read_unlock(&mrt_lock);
kfree_skb(skb);
return NETDEV_TX_OK;
+
+tx_err:
+ dev->stats.tx_errors++;
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
}
static int reg_vif_get_iflink(const struct net_device *dev)
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 51c9f75f34b9..1e03305c0549 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1021,6 +1021,9 @@ static netdev_tx_t sit_tunnel_xmit__(struct sk_buff *skb,
static netdev_tx_t sit_tunnel_xmit(struct sk_buff *skb,
struct net_device *dev)
{
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
+
switch (skb->protocol) {
case htons(ETH_P_IP):
sit_tunnel_xmit__(skb, dev, IPPROTO_IPIP);
--
2.20.1.415.g653613c723-goog
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