nf_reject_ipv6.rar_Too Short_nf_reject_ipv4.ko

/* (C) 1999-2001 Paul `Rusty' Russell * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/module.h> #include <net/ipv6.h> #include <net/ip6_route.h> #include <net/ip6_fib.h> #include <net/ip6_checksum.h> #include <net/netfilter/ipv6/nf_reject.h> #include <linux/netfilter_ipv6.h> #include <net/netfilter/ipv6/nf_reject.h> const struct tcphdr *nf_reject_ip6_tcphdr_get(struct sk_buff *oldskb, struct tcphdr *otcph, unsigned int *otcplen, int hook) { const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); u8 proto; __be16 frag_off; int tcphoff; proto = oip6h->nexthdr; tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto, &frag_off); if ((tcphoff < 0) || (tcphoff > oldskb->len)) { pr_debug("Cannot get TCP header.\n"); return NULL; } *otcplen = oldskb->len - tcphoff; /* IP header checks: fragment, too short. */ if (proto != IPPROTO_TCP || *otcplen < sizeof(struct tcphdr)) { pr_debug("proto(%d) != IPPROTO_TCP or too short (len = %d)\n", proto, *otcplen); return NULL; } otcph = skb_header_pointer(oldskb, tcphoff, sizeof(struct tcphdr), otcph); if (otcph == NULL) return NULL; /* No RST for RST. */ if (otcph->rst) { pr_debug("RST is set\n"); return NULL; } /* Check checksum. */ if (nf_ip6_checksum(oldskb, hook, tcphoff, IPPROTO_TCP)) { pr_debug("TCP checksum is invalid\n"); return NULL; } return otcph; } EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_get); struct ipv6hdr *nf_reject_ip6hdr_put(struct sk_buff *nskb, const struct sk_buff *oldskb, __be16 protocol, int hoplimit) { struct ipv6hdr *ip6h; const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); #define DEFAULT_TOS_VALUE 0x0U const __u8 tclass = DEFAULT_TOS_VALUE; skb_put(nskb, sizeof(struct ipv6hdr)); skb_reset_network_header(nskb); ip6h = ipv6_hdr(nskb); ip6_flow_hdr(ip6h, tclass, 0); ip6h->hop_limit = hoplimit; ip6h->nexthdr = protocol; ip6h->saddr = oip6h->daddr; ip6h->daddr = oip6h->saddr; nskb->protocol = htons(ETH_P_IPV6); return ip6h; } EXPORT_SYMBOL_GPL(nf_reject_ip6hdr_put); void nf_reject_ip6_tcphdr_put(struct sk_buff *nskb, const struct sk_buff *oldskb, const struct tcphdr *oth, unsigned int otcplen) { struct tcphdr *tcph; int needs_ack; skb_reset_transport_header(nskb); tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); /* Truncate to length (no data) */ tcph->doff = sizeof(struct tcphdr)/4; tcph->source = oth->dest; tcph->dest = oth->source; if (oth->ack) { needs_ack = 0; tcph->seq = oth->ack_seq; tcph->ack_seq = 0; } else { needs_ack = 1; tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin + otcplen - (oth->doff<<2)); tcph->seq = 0; } /* Reset flags */ ((u_int8_t *)tcph)[13] = 0; tcph->rst = 1; tcph->ack = needs_ack; tcph->window = 0; tcph->urg_ptr = 0; tcph->check = 0; /* Adjust TCP checksum */ tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr, &ipv6_hdr(nskb)->daddr, sizeof(struct tcphdr), IPPROTO_TCP, csum_partial(tcph, sizeof(struct tcphdr), 0)); } EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_put); void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook) { struct sk_buff *nskb; struct tcphdr _otcph; const struct tcphdr *otcph; unsigned int otcplen, hh_len; const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); struct ipv6hdr *ip6h; struct dst_entry *dst = NULL; struct flowi6 fl6; if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) || (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) { pr_debug("addr is not unicast.\n"); return; } otcph = nf_reject_ip6_tcphdr_get(oldskb, &_otcph, &otcplen, hook); if (!otcph) return; memset(&fl6, 0, sizeof(fl6)); fl6.flowi6_proto = IPPROTO_TCP; fl6.saddr = oip6h->daddr; fl6.daddr = oip6h->saddr; fl6.fl6_sport = otcph->dest; fl6.fl6_dport = otcph->source; security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6)); dst = ip6_route_output(net, NULL, &fl6); if (dst == NULL || dst->error) { dst_release(dst); return; } dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); if (IS_ERR(dst)) return; hh_len = (dst->dev->hard_header_len + 15)&~15; nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr) + sizeof(struct tcphdr) + dst->trailer_len, GFP_ATOMIC); if (!nskb) { net_dbg_ratelimited("cannot alloc skb\n"); dst_release(dst); return; } skb_dst_set(nskb, dst); skb_reserve(nskb, hh_len + dst->header_len); ip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP, ip6_dst_hoplimit(dst)); nf_reject_ip6_tcphdr_put(nskb, oldskb, otcph, otcplen); nf_ct_attach(nskb, oldskb); #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) /* If we use ip6_local_out for bridged traffic, the MAC source on * the RST will be ours, instead of the destination's. This confuses * some routers/firewalls, and they drop the packet. So we need to * build the eth header using the original destination's MAC as the * source, and send the RST packet directly. */ if (oldskb->nf_bridge) { struct ethhdr *oeth = eth_hdr(oldskb); nskb->dev = oldskb->nf_bridge->physindev; nskb->protocol = htons(ETH_P_IPV6); ip6h->payload_len = htons(sizeof(struct tcphdr)); if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol), oeth->h_source, oeth->h_dest, nskb->len) < 0) return; dev_queue_xmit(nskb); } else #endif ip6_local_out(nskb); } EXPORT_SYMBOL_GPL(nf_send_reset6); MODULE_LICENSE("GPL");