From cb9f1b783850b14cbd7f87d061d784a666dfba1f Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Sun, 30 Dec 2018 17:24:36 -0500 Subject: 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 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'include/net') 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; -- cgit v1.2.3