From eccc1bb8d4b4cf68d3c9becb083fa94ada7d495c Mon Sep 17 00:00:00 2001 From: stephen hemminger Date: Tue, 25 Sep 2012 11:02:48 +0000 Subject: tunnel: drop packet if ECN present with not-ECT Linux tunnels were written before RFC6040 and therefore never implemented the corner case of ECN getting set in the outer header and the inner header not being ready for it. Section 4.2. Default Tunnel Egress Behaviour. o If the inner ECN field is Not-ECT, the decapsulator MUST NOT propagate any other ECN codepoint onwards. This is because the inner Not-ECT marking is set by transports that rely on dropped packets as an indication of congestion and would not understand or respond to any other ECN codepoint [RFC4774]. Specifically: * If the inner ECN field is Not-ECT and the outer ECN field is CE, the decapsulator MUST drop the packet. * If the inner ECN field is Not-ECT and the outer ECN field is Not-ECT, ECT(0), or ECT(1), the decapsulator MUST forward the outgoing packet with the ECN field cleared to Not-ECT. This patch moves the ECN decap logic out of the individual tunnels into a common place. It also adds logging to allow detecting broken systems that set ECN bits incorrectly when tunneling (or an intermediate router might be changing the header). Overloads rx_frame_error to keep track of ECN related error. Thanks to Chris Wright who caught this while reviewing the new VXLAN tunnel. This code was tested by injecting faulty logic in other end GRE to send incorrectly encapsulated packets. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/ip_gre.c | 38 ++++++++++++++++++++++---------------- net/ipv4/ipip.c | 42 +++++++++++++++++++++++++----------------- 2 files changed, 47 insertions(+), 33 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 1c012cb2cb9..ef0b861ce04 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -120,6 +120,10 @@ Alexey Kuznetsov. */ +static bool log_ecn_error = true; +module_param(log_ecn_error, bool, 0644); +MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN"); + static struct rtnl_link_ops ipgre_link_ops __read_mostly; static int ipgre_tunnel_init(struct net_device *dev); static void ipgre_tunnel_setup(struct net_device *dev); @@ -204,7 +208,9 @@ static struct rtnl_link_stats64 *ipgre_get_stats64(struct net_device *dev, tot->rx_crc_errors = dev->stats.rx_crc_errors; tot->rx_fifo_errors = dev->stats.rx_fifo_errors; tot->rx_length_errors = dev->stats.rx_length_errors; + tot->rx_frame_errors = dev->stats.rx_frame_errors; tot->rx_errors = dev->stats.rx_errors; + tot->tx_fifo_errors = dev->stats.tx_fifo_errors; tot->tx_carrier_errors = dev->stats.tx_carrier_errors; tot->tx_dropped = dev->stats.tx_dropped; @@ -587,17 +593,6 @@ static void ipgre_err(struct sk_buff *skb, u32 info) t->err_time = jiffies; } -static inline void ipgre_ecn_decapsulate(const struct iphdr *iph, struct sk_buff *skb) -{ - if (INET_ECN_is_ce(iph->tos)) { - if (skb->protocol == htons(ETH_P_IP)) { - IP_ECN_set_ce(ip_hdr(skb)); - } else if (skb->protocol == htons(ETH_P_IPV6)) { - IP6_ECN_set_ce(ipv6_hdr(skb)); - } - } -} - static inline u8 ipgre_ecn_encapsulate(u8 tos, const struct iphdr *old_iph, struct sk_buff *skb) { @@ -620,6 +615,7 @@ static int ipgre_rcv(struct sk_buff *skb) struct ip_tunnel *tunnel; int offset = 4; __be16 gre_proto; + int err; if (!pskb_may_pull(skb, 16)) goto drop; @@ -723,17 +719,27 @@ static int ipgre_rcv(struct sk_buff *skb) skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN); } + __skb_tunnel_rx(skb, tunnel->dev); + + skb_reset_network_header(skb); + err = IP_ECN_decapsulate(iph, skb); + if (unlikely(err)) { + if (log_ecn_error) + net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n", + &iph->saddr, iph->tos); + if (err > 1) { + ++tunnel->dev->stats.rx_frame_errors; + ++tunnel->dev->stats.rx_errors; + goto drop; + } + } + tstats = this_cpu_ptr(tunnel->dev->tstats); u64_stats_update_begin(&tstats->syncp); tstats->rx_packets++; tstats->rx_bytes += skb->len; u64_stats_update_end(&tstats->syncp); - __skb_tunnel_rx(skb, tunnel->dev); - - skb_reset_network_header(skb); - ipgre_ecn_decapsulate(iph, skb); - netif_rx(skb); return 0; diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c index 618bde867ac..e15b45297c0 100644 --- a/net/ipv4/ipip.c +++ b/net/ipv4/ipip.c @@ -120,6 +120,10 @@ #define HASH_SIZE 16 #define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF) +static bool log_ecn_error = true; +module_param(log_ecn_error, bool, 0644); +MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN"); + static int ipip_net_id __read_mostly; struct ipip_net { struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE]; @@ -400,28 +404,18 @@ out: return err; } -static inline void ipip_ecn_decapsulate(const struct iphdr *outer_iph, - struct sk_buff *skb) -{ - struct iphdr *inner_iph = ip_hdr(skb); - - if (INET_ECN_is_ce(outer_iph->tos)) - IP_ECN_set_ce(inner_iph); -} - static int ipip_rcv(struct sk_buff *skb) { struct ip_tunnel *tunnel; const struct iphdr *iph = ip_hdr(skb); + int err; tunnel = ipip_tunnel_lookup(dev_net(skb->dev), iph->saddr, iph->daddr); if (tunnel != NULL) { struct pcpu_tstats *tstats; - if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { - kfree_skb(skb); - return 0; - } + if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) + goto drop; secpath_reset(skb); @@ -430,21 +424,35 @@ static int ipip_rcv(struct sk_buff *skb) skb->protocol = htons(ETH_P_IP); skb->pkt_type = PACKET_HOST; + __skb_tunnel_rx(skb, tunnel->dev); + + err = IP_ECN_decapsulate(iph, skb); + if (unlikely(err)) { + if (log_ecn_error) + net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n", + &iph->saddr, iph->tos); + if (err > 1) { + ++tunnel->dev->stats.rx_frame_errors; + ++tunnel->dev->stats.rx_errors; + goto drop; + } + } + tstats = this_cpu_ptr(tunnel->dev->tstats); u64_stats_update_begin(&tstats->syncp); tstats->rx_packets++; tstats->rx_bytes += skb->len; u64_stats_update_end(&tstats->syncp); - __skb_tunnel_rx(skb, tunnel->dev); - - ipip_ecn_decapsulate(iph, skb); - netif_rx(skb); return 0; } return -1; + +drop: + kfree_skb(skb); + return 0; } /* -- cgit v1.2.3-70-g09d2