From a7f87b47e67e4341f6175cdb80e5c2eaadf30dcb Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sat, 30 Dec 2017 22:41:46 +0100 Subject: netfilter: remove defensive check on malformed packets from raw sockets Users cannot forge malformed IPv4/IPv6 headers via raw sockets that they can inject into the stack. Specifically, not for IPv4 since 55888dfb6ba7 ("AF_RAW: Augment raw_send_hdrinc to expand skb to fit iphdr->ihl (v2)"). IPv6 raw sockets also ensure that packets have a well-formed IPv6 header available in the skbuff. At quick glance, br_netfilter also validates layer 3 headers and it drops malformed both IPv4 and IPv6 packets. Therefore, let's remove this defensive check all over the place. Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/iptable_filter.c | 6 ------ net/ipv4/netfilter/iptable_mangle.c | 5 ----- net/ipv4/netfilter/iptable_raw.c | 6 ------ net/ipv4/netfilter/iptable_security.c | 6 ------ net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 5 ----- net/ipv4/netfilter/nf_nat_l3proto_ipv4.c | 10 ---------- net/ipv4/netfilter/nf_tables_ipv4.c | 17 +---------------- net/ipv4/netfilter/nft_chain_route_ipv4.c | 5 ----- 8 files changed, 1 insertion(+), 59 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/netfilter/iptable_filter.c b/net/ipv4/netfilter/iptable_filter.c index 7667f223d7f8..9ac92ea7b93c 100644 --- a/net/ipv4/netfilter/iptable_filter.c +++ b/net/ipv4/netfilter/iptable_filter.c @@ -38,12 +38,6 @@ static unsigned int iptable_filter_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { - if (state->hook == NF_INET_LOCAL_OUT && - (skb->len < sizeof(struct iphdr) || - ip_hdrlen(skb) < sizeof(struct iphdr))) - /* root is playing with raw sockets. */ - return NF_ACCEPT; - return ipt_do_table(skb, state, state->net->ipv4.iptable_filter); } diff --git a/net/ipv4/netfilter/iptable_mangle.c b/net/ipv4/netfilter/iptable_mangle.c index aebdb337fd7e..dea138ca8925 100644 --- a/net/ipv4/netfilter/iptable_mangle.c +++ b/net/ipv4/netfilter/iptable_mangle.c @@ -49,11 +49,6 @@ ipt_mangle_out(struct sk_buff *skb, const struct nf_hook_state *state) u_int32_t mark; int err; - /* root is playing with raw sockets. */ - if (skb->len < sizeof(struct iphdr) || - ip_hdrlen(skb) < sizeof(struct iphdr)) - return NF_ACCEPT; - /* Save things which could affect route */ mark = skb->mark; iph = ip_hdr(skb); diff --git a/net/ipv4/netfilter/iptable_raw.c b/net/ipv4/netfilter/iptable_raw.c index 2642ecd2645c..a869d1fea7d9 100644 --- a/net/ipv4/netfilter/iptable_raw.c +++ b/net/ipv4/netfilter/iptable_raw.c @@ -26,12 +26,6 @@ static unsigned int iptable_raw_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { - if (state->hook == NF_INET_LOCAL_OUT && - (skb->len < sizeof(struct iphdr) || - ip_hdrlen(skb) < sizeof(struct iphdr))) - /* root is playing with raw sockets. */ - return NF_ACCEPT; - return ipt_do_table(skb, state, state->net->ipv4.iptable_raw); } diff --git a/net/ipv4/netfilter/iptable_security.c b/net/ipv4/netfilter/iptable_security.c index ff226596e4b5..e5379fe57b64 100644 --- a/net/ipv4/netfilter/iptable_security.c +++ b/net/ipv4/netfilter/iptable_security.c @@ -43,12 +43,6 @@ static unsigned int iptable_security_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { - if (state->hook == NF_INET_LOCAL_OUT && - (skb->len < sizeof(struct iphdr) || - ip_hdrlen(skb) < sizeof(struct iphdr))) - /* Somebody is playing with raw sockets. */ - return NF_ACCEPT; - return ipt_do_table(skb, state, state->net->ipv4.iptable_security); } diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c index bb2c868a5621..de213a397ea8 100644 --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c @@ -154,11 +154,6 @@ static unsigned int ipv4_conntrack_local(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) { - /* root is playing with raw sockets. */ - if (skb->len < sizeof(struct iphdr) || - ip_hdrlen(skb) < sizeof(struct iphdr)) - return NF_ACCEPT; - if (ip_is_fragment(ip_hdr(skb))) /* IP_NODEFRAG setsockopt set */ return NF_ACCEPT; diff --git a/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c b/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c index 0443ca4120b0..f7ff6a364d7b 100644 --- a/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c +++ b/net/ipv4/netfilter/nf_nat_l3proto_ipv4.c @@ -356,11 +356,6 @@ nf_nat_ipv4_out(void *priv, struct sk_buff *skb, #endif unsigned int ret; - /* root is playing with raw sockets. */ - if (skb->len < sizeof(struct iphdr) || - ip_hdrlen(skb) < sizeof(struct iphdr)) - return NF_ACCEPT; - ret = nf_nat_ipv4_fn(priv, skb, state, do_chain); #ifdef CONFIG_XFRM if (ret != NF_DROP && ret != NF_STOLEN && @@ -396,11 +391,6 @@ nf_nat_ipv4_local_fn(void *priv, struct sk_buff *skb, unsigned int ret; int err; - /* root is playing with raw sockets. */ - if (skb->len < sizeof(struct iphdr) || - ip_hdrlen(skb) < sizeof(struct iphdr)) - return NF_ACCEPT; - ret = nf_nat_ipv4_fn(priv, skb, state, do_chain); if (ret != NF_DROP && ret != NF_STOLEN && (ct = nf_ct_get(skb, &ctinfo)) != NULL) { diff --git a/net/ipv4/netfilter/nf_tables_ipv4.c b/net/ipv4/netfilter/nf_tables_ipv4.c index 8aeb15c2b9b2..f4675253f1e6 100644 --- a/net/ipv4/netfilter/nf_tables_ipv4.c +++ b/net/ipv4/netfilter/nf_tables_ipv4.c @@ -30,21 +30,6 @@ static unsigned int nft_do_chain_ipv4(void *priv, return nft_do_chain(&pkt, priv); } -static unsigned int nft_ipv4_output(void *priv, - struct sk_buff *skb, - const struct nf_hook_state *state) -{ - if (unlikely(skb->len < sizeof(struct iphdr) || - ip_hdr(skb)->ihl < sizeof(struct iphdr) / 4)) { - if (net_ratelimit()) - pr_info("nf_tables_ipv4: ignoring short SOCK_RAW " - "packet\n"); - return NF_ACCEPT; - } - - return nft_do_chain_ipv4(priv, skb, state); -} - static struct nft_af_info nft_af_ipv4 __read_mostly = { .family = NFPROTO_IPV4, .nhooks = NF_INET_NUMHOOKS, @@ -91,7 +76,7 @@ static const struct nf_chain_type filter_ipv4 = { (1 << NF_INET_POST_ROUTING), .hooks = { [NF_INET_LOCAL_IN] = nft_do_chain_ipv4, - [NF_INET_LOCAL_OUT] = nft_ipv4_output, + [NF_INET_LOCAL_OUT] = nft_do_chain_ipv4, [NF_INET_FORWARD] = nft_do_chain_ipv4, [NF_INET_PRE_ROUTING] = nft_do_chain_ipv4, [NF_INET_POST_ROUTING] = nft_do_chain_ipv4, diff --git a/net/ipv4/netfilter/nft_chain_route_ipv4.c b/net/ipv4/netfilter/nft_chain_route_ipv4.c index fb3d49fb62fe..d965c225b9f6 100644 --- a/net/ipv4/netfilter/nft_chain_route_ipv4.c +++ b/net/ipv4/netfilter/nft_chain_route_ipv4.c @@ -33,11 +33,6 @@ static unsigned int nf_route_table_hook(void *priv, const struct iphdr *iph; int err; - /* root is playing with raw sockets. */ - if (skb->len < sizeof(struct iphdr) || - ip_hdrlen(skb) < sizeof(struct iphdr)) - return NF_ACCEPT; - nft_set_pktinfo(&pkt, skb, state); nft_set_pktinfo_ipv4(&pkt, skb); -- cgit v1.2.3-55-g7522