diff options
Diffstat (limited to 'net/ipv4/netfilter/nf_reject_ipv4.c')
| -rw-r--r-- | net/ipv4/netfilter/nf_reject_ipv4.c | 134 |
1 files changed, 129 insertions, 5 deletions
diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c index 93b07739807b..4eed5afca392 100644 --- a/net/ipv4/netfilter/nf_reject_ipv4.c +++ b/net/ipv4/netfilter/nf_reject_ipv4.c @@ -12,6 +12,128 @@ #include <linux/netfilter_ipv4.h> #include <linux/netfilter_bridge.h> +static int nf_reject_iphdr_validate(struct sk_buff *skb) +{ + struct iphdr *iph; + u32 len; + + if (!pskb_may_pull(skb, sizeof(struct iphdr))) + return 0; + + iph = ip_hdr(skb); + if (iph->ihl < 5 || iph->version != 4) + return 0; + + len = ntohs(iph->tot_len); + if (skb->len < len) + return 0; + else if (len < (iph->ihl*4)) + return 0; + + if (!pskb_may_pull(skb, iph->ihl*4)) + return 0; + + return 1; +} + +struct sk_buff *nf_reject_skb_v4_tcp_reset(struct net *net, + struct sk_buff *oldskb, + const struct net_device *dev, + int hook) +{ + const struct tcphdr *oth; + struct sk_buff *nskb; + struct iphdr *niph; + struct tcphdr _oth; + + if (!nf_reject_iphdr_validate(oldskb)) + return NULL; + + oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook); + if (!oth) + return NULL; + + nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + + LL_MAX_HEADER, GFP_ATOMIC); + if (!nskb) + return NULL; + + nskb->dev = (struct net_device *)dev; + + skb_reserve(nskb, LL_MAX_HEADER); + niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, + net->ipv4.sysctl_ip_default_ttl); + nf_reject_ip_tcphdr_put(nskb, oldskb, oth); + niph->tot_len = htons(nskb->len); + ip_send_check(niph); + + return nskb; +} +EXPORT_SYMBOL_GPL(nf_reject_skb_v4_tcp_reset); + +struct sk_buff *nf_reject_skb_v4_unreach(struct net *net, + struct sk_buff *oldskb, + const struct net_device *dev, + int hook, u8 code) +{ + struct sk_buff *nskb; + struct iphdr *niph; + struct icmphdr *icmph; + unsigned int len; + __wsum csum; + u8 proto; + + if (!nf_reject_iphdr_validate(oldskb)) + return NULL; + + /* IP header checks: fragment. */ + if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET)) + return NULL; + + /* RFC says return as much as we can without exceeding 576 bytes. */ + len = min_t(unsigned int, 536, oldskb->len); + + if (!pskb_may_pull(oldskb, len)) + return NULL; + + if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len))) + return NULL; + + proto = ip_hdr(oldskb)->protocol; + + if (!skb_csum_unnecessary(oldskb) && + nf_reject_verify_csum(proto) && + nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto)) + return NULL; + + nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) + + LL_MAX_HEADER + len, GFP_ATOMIC); + if (!nskb) + return NULL; + + nskb->dev = (struct net_device *)dev; + + skb_reserve(nskb, LL_MAX_HEADER); + niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP, + net->ipv4.sysctl_ip_default_ttl); + + skb_reset_transport_header(nskb); + icmph = skb_put_zero(nskb, sizeof(struct icmphdr)); + icmph->type = ICMP_DEST_UNREACH; + icmph->code = code; + + skb_put_data(nskb, skb_network_header(oldskb), len); + + csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0); + icmph->checksum = csum_fold(csum); + + niph->tot_len = htons(nskb->len); + ip_send_check(niph); + + return nskb; +} +EXPORT_SYMBOL_GPL(nf_reject_skb_v4_unreach); + const struct tcphdr *nf_reject_ip_tcphdr_get(struct sk_buff *oldskb, struct tcphdr *_oth, int hook) { @@ -112,7 +234,8 @@ static int nf_reject_fill_skb_dst(struct sk_buff *skb_in) } /* Send RST reply */ -void nf_send_reset(struct net *net, struct sk_buff *oldskb, int hook) +void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb, + int hook) { struct net_device *br_indev __maybe_unused; struct sk_buff *nskb; @@ -124,7 +247,8 @@ void nf_send_reset(struct net *net, struct sk_buff *oldskb, int hook) if (!oth) return; - if (hook == NF_INET_PRE_ROUTING && nf_reject_fill_skb_dst(oldskb)) + if ((hook == NF_INET_PRE_ROUTING || hook == NF_INET_INGRESS) && + nf_reject_fill_skb_dst(oldskb) < 0) return; if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) @@ -144,8 +268,7 @@ void nf_send_reset(struct net *net, struct sk_buff *oldskb, int hook) niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, ip4_dst_hoplimit(skb_dst(nskb))); nf_reject_ip_tcphdr_put(nskb, oldskb, oth); - - if (ip_route_me_harder(net, nskb->sk, nskb, RTN_UNSPEC)) + if (ip_route_me_harder(net, sk, nskb, RTN_UNSPEC)) goto free_nskb; niph = ip_hdr(nskb); @@ -193,7 +316,8 @@ void nf_send_unreach(struct sk_buff *skb_in, int code, int hook) if (iph->frag_off & htons(IP_OFFSET)) return; - if (hook == NF_INET_PRE_ROUTING && nf_reject_fill_skb_dst(skb_in)) + if ((hook == NF_INET_PRE_ROUTING || hook == NF_INET_INGRESS) && + nf_reject_fill_skb_dst(skb_in) < 0) return; if (skb_csum_unnecessary(skb_in) || !nf_reject_verify_csum(proto)) { |