From cb9f1b783850b14cbd7f87d061d784a666dfba1f Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Sun, 30 Dec 2018 17:24:36 -0500 Subject: [PATCH] ip: validate header length on virtual device xmit 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 Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller --- 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 #include #include +#include #include @@ -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); -- GitLab