From 8430eac2f6a3c2adce22d490e2ab8bb50d59077a Mon Sep 17 00:00:00 2001 From: Jozsef Kadlecsik Date: Mon, 9 Apr 2012 16:32:16 +0200 Subject: netfilter: nf_ct_ipv4: handle invalid IPv4 and IPv6 packets consistently IPv6 conntrack marked invalid packets as INVALID and let the user drop those by an explicit rule, while IPv4 conntrack dropped such packets itself. IPv4 conntrack is changed so that it marks INVALID packets and let the user to drop them. Signed-off-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c') diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c index de9da21113a1..750b06afd20e 100644 --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c @@ -74,12 +74,12 @@ static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph); if (iph == NULL) - return -NF_DROP; + return -NF_ACCEPT; /* Conntrack defragments packets, we might still see fragments * inside ICMP packets though. */ if (iph->frag_off & htons(IP_OFFSET)) - return -NF_DROP; + return -NF_ACCEPT; *dataoff = nhoff + (iph->ihl << 2); *protonum = iph->protocol; -- cgit v1.2.3 From 07153c6ec074257ade76a461429b567cff2b3a1e Mon Sep 17 00:00:00 2001 From: Jozsef Kadlecsik Date: Tue, 3 Apr 2012 22:02:01 +0200 Subject: netfilter: nf_ct_ipv4: packets with wrong ihl are invalid It was reported that the Linux kernel sometimes logs: klogd: [2629147.402413] kernel BUG at net / netfilter / nf_conntrack_proto_tcp.c: 447! klogd: [1072212.887368] kernel BUG at net / netfilter / nf_conntrack_proto_tcp.c: 392 ipv4_get_l4proto() in nf_conntrack_l3proto_ipv4.c and tcp_error() in nf_conntrack_proto_tcp.c should catch malformed packets, so the errors at the indicated lines - TCP options parsing - should not happen. However, tcp_error() relies on the "dataoff" offset to the TCP header, calculated by ipv4_get_l4proto(). But ipv4_get_l4proto() does not check bogus ihl values in IPv4 packets, which then can slip through tcp_error() and get caught at the TCP options parsing routines. The patch fixes ipv4_get_l4proto() by invalidating packets with bogus ihl value. The patch closes netfilter bugzilla id 771. Signed-off-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c') diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c index 750b06afd20e..cf73cc70ed2d 100644 --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c @@ -84,6 +84,14 @@ static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, *dataoff = nhoff + (iph->ihl << 2); *protonum = iph->protocol; + /* Check bogus IP headers */ + if (*dataoff > skb->len) { + pr_debug("nf_conntrack_ipv4: bogus IPv4 packet: " + "nhoff %u, ihl %u, skblen %u\n", + nhoff, iph->ihl << 2, skb->len); + return -NF_ACCEPT; + } + return NF_ACCEPT; } -- cgit v1.2.3