/*- * Copyright (c) 2010-2011 The NetBSD Foundation, Inc. * All rights reserved. * * This material is based upon work partially supported by The * NetBSD Foundation under a contract with Mindaugas Rasiukevicius. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * NPF module for packet construction routines. */ #ifdef _KERNEL #include __KERNEL_RCSID(0, "$NetBSD: npf_sendpkt.c,v 1.22.20.1 2023/03/14 17:09:21 martin Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include #endif #include "npf_impl.h" #define DEFAULT_IP_TTL (ip_defttl) #if defined(_NPF_STANDALONE) #define m_gethdr(t, f) (npf)->mbufops->alloc((npf), 0, 0) #define m_freem(m) (npc)->npc_ctx->mbufops->free(m) #define mtod(m,t) ((t)((npc)->npc_ctx->mbufops->getdata(m))) #endif #if !defined(INET6) || defined(_NPF_STANDALONE) #define in6_cksum(...) 0 #define ip6_output(...) 0 #define icmp6_error(m, ...) m_freem(m) #define npf_ip6_setscope(n, i) ((void)(i), 0) #endif #if defined(INET6) static int npf_ip6_setscope(const npf_cache_t *npc, struct ip6_hdr *ip6) { const struct ifnet *rcvif = npc->npc_nbuf->nb_ifp; if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) { return EINVAL; } if (in6_setscope(&ip6->ip6_src, rcvif, NULL) || in6_setscope(&ip6->ip6_dst, rcvif, NULL)) { return EINVAL; } return 0; } #endif /* * npf_return_tcp: return a TCP reset (RST) packet. */ static int npf_return_tcp(npf_cache_t *npc) { npf_t *npf = npc->npc_ctx; struct mbuf *m; struct ip *ip = NULL; struct ip6_hdr *ip6 = NULL; struct tcphdr *oth, *th; tcp_seq seq, ack; int tcpdlen, len; uint32_t win; /* Fetch relevant data. */ KASSERT(npf_iscached(npc, NPC_IP46)); KASSERT(npf_iscached(npc, NPC_LAYER4)); tcpdlen = npf_tcpsaw(npc, &seq, &ack, &win); oth = npc->npc_l4.tcp; if (oth->th_flags & TH_RST) { return 0; } /* Create and setup a network buffer. */ if (npf_iscached(npc, NPC_IP4)) { len = sizeof(struct ip) + sizeof(struct tcphdr); } else if (npf_iscached(npc, NPC_IP6)) { len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); } else { return EINVAL; } m = m_gethdr(M_DONTWAIT, MT_HEADER); if (m == NULL) { return ENOMEM; } #if !defined(_NPF_STANDALONE) m->m_data += max_linkhdr; m->m_len = len; m->m_pkthdr.len = len; (void)npf; #endif if (npf_iscached(npc, NPC_IP4)) { struct ip *oip = npc->npc_ip.v4; ip = mtod(m, struct ip *); memset(ip, 0, len); /* * First, partially fill IPv4 header for TCP checksum. * Note: IP length contains TCP header length. */ ip->ip_p = IPPROTO_TCP; ip->ip_src.s_addr = oip->ip_dst.s_addr; ip->ip_dst.s_addr = oip->ip_src.s_addr; ip->ip_len = htons(sizeof(struct tcphdr)); th = (struct tcphdr *)(ip + 1); } else { struct ip6_hdr *oip = npc->npc_ip.v6; KASSERT(npf_iscached(npc, NPC_IP6)); ip6 = mtod(m, struct ip6_hdr *); memset(ip6, 0, len); ip6->ip6_nxt = IPPROTO_TCP; ip6->ip6_hlim = IPV6_DEFHLIM; memcpy(&ip6->ip6_src, &oip->ip6_dst, sizeof(struct in6_addr)); memcpy(&ip6->ip6_dst, &oip->ip6_src, sizeof(struct in6_addr)); ip6->ip6_plen = htons(len); ip6->ip6_vfc = IPV6_VERSION; th = (struct tcphdr *)(ip6 + 1); } /* * Construct TCP header and compute the checksum. */ th->th_sport = oth->th_dport; th->th_dport = oth->th_sport; th->th_seq = htonl(ack); if (oth->th_flags & TH_SYN) { tcpdlen++; } th->th_ack = htonl(seq + tcpdlen); th->th_off = sizeof(struct tcphdr) >> 2; th->th_flags = TH_ACK | TH_RST; if (npf_iscached(npc, NPC_IP4)) { th->th_sum = in_cksum(m, len); /* * Second, fill the rest of IPv4 header and correct IP length. */ ip->ip_v = IPVERSION; ip->ip_hl = sizeof(struct ip) >> 2; ip->ip_tos = IPTOS_LOWDELAY; ip->ip_len = htons(len); ip->ip_ttl = DEFAULT_IP_TTL; } else { KASSERT(npf_iscached(npc, NPC_IP6)); th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), sizeof(struct tcphdr)); /* Handle IPv6 scopes */ if (npf_ip6_setscope(npc, ip6) != 0) { goto bad; } } /* don't look at our generated reject packets going out */ (void)npf_mbuf_add_tag(npc->npc_nbuf, m, NPF_NTAG_PASS); /* Pass to IP layer. */ if (npf_iscached(npc, NPC_IP4)) { return ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL); } return ip6_output(m, NULL, NULL, IPV6_FORWARDING, NULL, NULL, NULL); bad: m_freem(m); return EINVAL; } /* * npf_return_icmp: return an ICMP error. */ static int npf_return_icmp(const npf_cache_t *npc) { struct mbuf *m = nbuf_head_mbuf(npc->npc_nbuf); /* don't look at our generated reject packets going out */ (void)nbuf_add_tag(npc->npc_nbuf, NPF_NTAG_PASS); if (npf_iscached(npc, NPC_IP4)) { icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_ADMIN_PROHIBIT, 0, 0); return 0; } else if (npf_iscached(npc, NPC_IP6)) { /* Handle IPv6 scopes */ struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); if (npf_ip6_setscope(npc, ip6) != 0) { return EINVAL; } icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN, 0); return 0; } return EINVAL; } /* * npf_return_block: return TCP reset or ICMP host unreachable packet. * * => Returns true if the buffer was consumed (freed) and false otherwise. */ bool npf_return_block(npf_cache_t *npc, const int retfl) { if (!npf_iscached(npc, NPC_IP46) || !npf_iscached(npc, NPC_LAYER4)) { return false; } switch (npc->npc_proto) { case IPPROTO_TCP: if (retfl & NPF_RULE_RETRST) { (void)npf_return_tcp(npc); } break; case IPPROTO_UDP: if (retfl & NPF_RULE_RETICMP) if (npf_return_icmp(npc) == 0) return true; break; } return false; }