/* * Copyright (c) 1982, 1986, 1988, 1993 * The Regents of the University of California. * Copyright (c) 2005 Andre Oppermann, Internet Business Solutions AG. * All rights reserved. * * 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. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. */ #include __FBSDID("$FreeBSD$"); #include "opt_ipstealth.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static int ip_dosourceroute = 0; SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW, &ip_dosourceroute, 0, "Enable forwarding source routed IP packets"); static int ip_acceptsourceroute = 0; SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute, CTLFLAG_RW, &ip_acceptsourceroute, 0, "Enable accepting source routed IP packets"); int ip_doopts = 1; /* 0 = ignore, 1 = process, 2 = reject */ SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW, &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)"); static void save_rte(struct mbuf *m, u_char *, struct in_addr); /* * Do option processing on a datagram, possibly discarding it if bad options * are encountered, or forwarding it if source-routed. * * The pass argument is used when operating in the IPSTEALTH mode to tell * what options to process: [LS]SRR (pass 0) or the others (pass 1). The * reason for as many as two passes is that when doing IPSTEALTH, non-routing * options should be processed only if the packet is for us. * * Returns 1 if packet has been forwarded/freed, 0 if the packet should be * processed further. */ int ip_dooptions(struct mbuf *m, int pass) { struct ip *ip = mtod(m, struct ip *); u_char *cp; struct in_ifaddr *ia; int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; struct in_addr *sin, dst; uint32_t ntime; struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; /* Ignore or reject packets with IP options. */ if (ip_doopts == 0) return 0; else if (ip_doopts == 2) { type = ICMP_UNREACH; code = ICMP_UNREACH_FILTER_PROHIB; goto bad; } dst = ip->ip_dst; cp = (u_char *)(ip + 1); cnt = (ip->ip_hl << 2) - sizeof (struct ip); for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[IPOPT_OPTVAL]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) optlen = 1; else { if (cnt < IPOPT_OLEN + sizeof(*cp)) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } optlen = cp[IPOPT_OLEN]; if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } } switch (opt) { default: break; /* * Source routing with record. Find interface with current * destination address. If none on this machine then drop if * strictly routed, or do nothing if loosely routed. Record * interface address and bring up next address component. If * strictly routed make sure next address is on directly * accessible net. */ case IPOPT_LSRR: case IPOPT_SSRR: #ifdef IPSTEALTH if (V_ipstealth && pass > 0) break; #endif if (optlen < IPOPT_OFFSET + sizeof(*cp)) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } ipaddr.sin_addr = ip->ip_dst; if (ifa_ifwithaddr_check((struct sockaddr *)&ipaddr) == 0) { if (opt == IPOPT_SSRR) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } if (!ip_dosourceroute) goto nosourcerouting; /* * Loose routing, and not at next destination * yet; nothing to do except forward. */ break; } off--; /* 0 origin */ if (off > optlen - (int)sizeof(struct in_addr)) { /* * End of source route. Should be for us. */ if (!ip_acceptsourceroute) goto nosourcerouting; save_rte(m, cp, ip->ip_src); break; } #ifdef IPSTEALTH if (V_ipstealth) goto dropit; #endif if (!ip_dosourceroute) { if (V_ipforwarding) { char buf[16]; /* aaa.bbb.ccc.ddd\0 */ /* * Acting as a router, so generate * ICMP */ nosourcerouting: strcpy(buf, inet_ntoa(ip->ip_dst)); log(LOG_WARNING, "attempted source route from %s to %s\n", inet_ntoa(ip->ip_src), buf); type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } else { /* * Not acting as a router, so * silently drop. */ #ifdef IPSTEALTH dropit: #endif IPSTAT_INC(ips_cantforward); m_freem(m); return (1); } } /* * locate outgoing interface */ (void)memcpy(&ipaddr.sin_addr, cp + off, sizeof(ipaddr.sin_addr)); if (opt == IPOPT_SSRR) { #define INA struct in_ifaddr * #define SA struct sockaddr * if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL) ia = (INA)ifa_ifwithnet((SA)&ipaddr, 0); } else /* XXX MRT 0 for routing */ ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m)); if (ia == NULL) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } ip->ip_dst = ipaddr.sin_addr; (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), sizeof(struct in_addr)); ifa_free(&ia->ia_ifa); cp[IPOPT_OFFSET] += sizeof(struct in_addr); /* * Let ip_intr's mcast routing check handle mcast pkts */ forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); break; case IPOPT_RR: #ifdef IPSTEALTH if (V_ipstealth && pass == 0) break; #endif if (optlen < IPOPT_OFFSET + sizeof(*cp)) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } /* * If no space remains, ignore. */ off--; /* 0 origin */ if (off > optlen - (int)sizeof(struct in_addr)) break; (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst, sizeof(ipaddr.sin_addr)); /* * Locate outgoing interface; if we're the * destination, use the incoming interface (should be * same). */ if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL && (ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m))) == NULL) { type = ICMP_UNREACH; code = ICMP_UNREACH_HOST; goto bad; } (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), sizeof(struct in_addr)); ifa_free(&ia->ia_ifa); cp[IPOPT_OFFSET] += sizeof(struct in_addr); break; case IPOPT_TS: #ifdef IPSTEALTH if (V_ipstealth && pass == 0) break; #endif code = cp - (u_char *)ip; if (optlen < 4 || optlen > 40) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } if ((off = cp[IPOPT_OFFSET]) < 5) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } if (off > optlen - (int)sizeof(int32_t)) { cp[IPOPT_OFFSET + 1] += (1 << 4); if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } break; } off--; /* 0 origin */ sin = (struct in_addr *)(cp + off); switch (cp[IPOPT_OFFSET + 1] & 0x0f) { case IPOPT_TS_TSONLY: break; case IPOPT_TS_TSANDADDR: if (off + sizeof(uint32_t) + sizeof(struct in_addr) > optlen) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } ipaddr.sin_addr = dst; ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, m->m_pkthdr.rcvif); if (ia == NULL) continue; (void)memcpy(sin, &IA_SIN(ia)->sin_addr, sizeof(struct in_addr)); ifa_free(&ia->ia_ifa); cp[IPOPT_OFFSET] += sizeof(struct in_addr); off += sizeof(struct in_addr); break; case IPOPT_TS_PRESPEC: if (off + sizeof(uint32_t) + sizeof(struct in_addr) > optlen) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } (void)memcpy(&ipaddr.sin_addr, sin, sizeof(struct in_addr)); if (ifa_ifwithaddr_check((SA)&ipaddr) == 0) continue; cp[IPOPT_OFFSET] += sizeof(struct in_addr); off += sizeof(struct in_addr); break; default: code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip; goto bad; } ntime = iptime(); (void)memcpy(cp + off, &ntime, sizeof(uint32_t)); cp[IPOPT_OFFSET] += sizeof(uint32_t); } } if (forward && V_ipforwarding) { ip_forward(m, 1); return (1); } return (0); bad: icmp_error(m, type, code, 0, 0); IPSTAT_INC(ips_badoptions); return (1); } /* * Save incoming source route for use in replies, to be picked up later by * ip_srcroute if the receiver is interested. */ static void save_rte(struct mbuf *m, u_char *option, struct in_addr dst) { unsigned olen; struct ipopt_tag *opts; opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS, sizeof(struct ipopt_tag), M_NOWAIT); if (opts == NULL) return; olen = option[IPOPT_OLEN]; if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst))) { m_tag_free((struct m_tag *)opts); return; } bcopy(option, opts->ip_srcrt.srcopt, olen); opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); opts->ip_srcrt.dst = dst; m_tag_prepend(m, (struct m_tag *)opts); } /* * Retrieve incoming source route for use in replies, in the same form used * by setsockopt. The first hop is placed before the options, will be * removed later. */ struct mbuf * ip_srcroute(struct mbuf *m0) { struct in_addr *p, *q; struct mbuf *m; struct ipopt_tag *opts; opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL); if (opts == NULL) return (NULL); if (opts->ip_nhops == 0) return (NULL); m = m_get(M_DONTWAIT, MT_DATA); if (m == NULL) return (NULL); #define OPTSIZ (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt)) /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ m->m_len = opts->ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + OPTSIZ; /* * First, save first hop for return route. */ p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]); *(mtod(m, struct in_addr *)) = *p--; /* * Copy option fields and padding (nop) to mbuf. */ opts->ip_srcrt.nop = IPOPT_NOP; opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr), &(opts->ip_srcrt.nop), OPTSIZ); q = (struct in_addr *)(mtod(m, caddr_t) + sizeof(struct in_addr) + OPTSIZ); #undef OPTSIZ /* * Record return path as an IP source route, reversing the path * (pointers are now aligned). */ while (p >= opts->ip_srcrt.route) { *q++ = *p--; } /* * Last hop goes to final destination. */ *q = opts->ip_srcrt.dst; m_tag_delete(m0, (struct m_tag *)opts); return (m); } /* * Strip out IP options, at higher level protocol in the kernel. */ void ip_stripoptions(struct mbuf *m) { int i; struct ip *ip = mtod(m, struct ip *); caddr_t opts; int olen; olen = (ip->ip_hl << 2) - sizeof (struct ip); opts = (caddr_t)(ip + 1); i = m->m_len - (sizeof (struct ip) + olen); bcopy(opts + olen, opts, (unsigned)i); m->m_len -= olen; if (m->m_flags & M_PKTHDR) m->m_pkthdr.len -= olen; ip->ip_v = IPVERSION; ip->ip_hl = sizeof(struct ip) >> 2; } /* * Insert IP options into preformed packet. Adjust IP destination as * required for IP source routing, as indicated by a non-zero in_addr at the * start of the options. * * XXX This routine assumes that the packet has no options in place. */ struct mbuf * ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen) { struct ipoption *p = mtod(opt, struct ipoption *); struct mbuf *n; struct ip *ip = mtod(m, struct ip *); unsigned optlen; optlen = opt->m_len - sizeof(p->ipopt_dst); if (optlen + ip->ip_len > IP_MAXPACKET) { *phlen = 0; return (m); /* XXX should fail */ } if (p->ipopt_dst.s_addr) ip->ip_dst = p->ipopt_dst; if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) { MGETHDR(n, M_DONTWAIT, MT_DATA); if (n == NULL) { *phlen = 0; return (m); } M_MOVE_PKTHDR(n, m); n->m_pkthdr.rcvif = NULL; n->m_pkthdr.len += optlen; m->m_len -= sizeof(struct ip); m->m_data += sizeof(struct ip); n->m_next = m; m = n; m->m_len = optlen + sizeof(struct ip); m->m_data += max_linkhdr; bcopy(ip, mtod(m, void *), sizeof(struct ip)); } else { m->m_data -= optlen; m->m_len += optlen; m->m_pkthdr.len += optlen; bcopy(ip, mtod(m, void *), sizeof(struct ip)); } ip = mtod(m, struct ip *); bcopy(p->ipopt_list, ip + 1, optlen); *phlen = sizeof(struct ip) + optlen; ip->ip_v = IPVERSION; ip->ip_hl = *phlen >> 2; ip->ip_len += optlen; return (m); } /* * Copy options from ip to jp, omitting those not copied during * fragmentation. */ int ip_optcopy(struct ip *ip, struct ip *jp) { u_char *cp, *dp; int opt, optlen, cnt; cp = (u_char *)(ip + 1); dp = (u_char *)(jp + 1); cnt = (ip->ip_hl << 2) - sizeof (struct ip); for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[0]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) { /* Preserve for IP mcast tunnel's LSRR alignment. */ *dp++ = IPOPT_NOP; optlen = 1; continue; } KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp), ("ip_optcopy: malformed ipv4 option")); optlen = cp[IPOPT_OLEN]; KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt, ("ip_optcopy: malformed ipv4 option")); /* Bogus lengths should have been caught by ip_dooptions. */ if (optlen > cnt) optlen = cnt; if (IPOPT_COPIED(opt)) { bcopy(cp, dp, optlen); dp += optlen; } } for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++) *dp++ = IPOPT_EOL; return (optlen); } /* * Set up IP options in pcb for insertion in output packets. Store in mbuf * with pointer in pcbopt, adding pseudo-option with destination address if * source routed. */ int ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m) { int cnt, optlen; u_char *cp; struct mbuf **pcbopt; u_char opt; INP_WLOCK_ASSERT(inp); pcbopt = &inp->inp_options; /* turn off any old options */ if (*pcbopt) (void)m_free(*pcbopt); *pcbopt = 0; if (m == NULL || m->m_len == 0) { /* * Only turning off any previous options. */ if (m != NULL) (void)m_free(m); return (0); } if (m->m_len % sizeof(int32_t)) goto bad; /* * IP first-hop destination address will be stored before actual * options; move other options back and clear it when none present. */ if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN]) goto bad; cnt = m->m_len; m->m_len += sizeof(struct in_addr); cp = mtod(m, u_char *) + sizeof(struct in_addr); bcopy(mtod(m, void *), cp, (unsigned)cnt); bzero(mtod(m, void *), sizeof(struct in_addr)); for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[IPOPT_OPTVAL]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) optlen = 1; else { if (cnt < IPOPT_OLEN + sizeof(*cp)) goto bad; optlen = cp[IPOPT_OLEN]; if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) goto bad; } switch (opt) { default: break; case IPOPT_LSRR: case IPOPT_SSRR: /* * User process specifies route as: * * ->A->B->C->D * * D must be our final destination (but we can't * check that since we may not have connected yet). * A is first hop destination, which doesn't appear * in actual IP option, but is stored before the * options. */ /* XXX-BZ PRIV_NETINET_SETHDROPTS? */ if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr)) goto bad; m->m_len -= sizeof(struct in_addr); cnt -= sizeof(struct in_addr); optlen -= sizeof(struct in_addr); cp[IPOPT_OLEN] = optlen; /* * Move first hop before start of options. */ bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t), sizeof(struct in_addr)); /* * Then copy rest of options back * to close up the deleted entry. */ bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)), &cp[IPOPT_OFFSET+1], (unsigned)cnt - (IPOPT_MINOFF - 1)); break; } } if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr)) goto bad; *pcbopt = m; return (0); bad: (void)m_free(m); return (EINVAL); } /* * Check for the presence of the IP Router Alert option [RFC2113] * in the header of an IPv4 datagram. * * This call is not intended for use from the forwarding path; it is here * so that protocol domains may check for the presence of the option. * Given how FreeBSD's IPv4 stack is currently structured, the Router Alert * option does not have much relevance to the implementation, though this * may change in future. * Router alert options SHOULD be passed if running in IPSTEALTH mode and * we are not the endpoint. * Length checks on individual options should already have been peformed * by ip_dooptions() therefore they are folded under INVARIANTS here. * * Return zero if not present or options are invalid, non-zero if present. */ int ip_checkrouteralert(struct mbuf *m) { struct ip *ip = mtod(m, struct ip *); u_char *cp; int opt, optlen, cnt, found_ra; found_ra = 0; cp = (u_char *)(ip + 1); cnt = (ip->ip_hl << 2) - sizeof (struct ip); for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[IPOPT_OPTVAL]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) optlen = 1; else { #ifdef INVARIANTS if (cnt < IPOPT_OLEN + sizeof(*cp)) break; #endif optlen = cp[IPOPT_OLEN]; #ifdef INVARIANTS if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) break; #endif } switch (opt) { case IPOPT_RA: #ifdef INVARIANTS if (optlen != IPOPT_OFFSET + sizeof(uint16_t) || (*((uint16_t *)&cp[IPOPT_OFFSET]) != 0)) break; else #endif found_ra = 1; break; default: break; } } return (found_ra); }