/* $FreeBSD$ */ /* $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $ */ /* * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * 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. * 3. Neither the name of the project 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 PROJECT 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 PROJECT 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. */ /* * My grandfather said that there's a devil inside tunnelling technology... * * We have surprisingly many protocols that want packets with IP protocol * #4 or #41. Here's a list of protocols that want protocol #41: * RFC1933 configured tunnel * RFC1933 automatic tunnel * RFC2401 IPsec tunnel * RFC2473 IPv6 generic packet tunnelling * RFC2529 6over4 tunnel * mobile-ip6 (uses RFC2473) * 6to4 tunnel * Here's a list of protocol that want protocol #4: * RFC1853 IPv4-in-IPv4 tunnelling * RFC2003 IPv4 encapsulation within IPv4 * RFC2344 reverse tunnelling for mobile-ip4 * RFC2401 IPsec tunnel * Well, what can I say. They impose different en/decapsulation mechanism * from each other, so they need separate protocol handler. The only one * we can easily determine by protocol # is IPsec, which always has * AH/ESP/IPComp header right after outer IP header. * * So, clearly good old protosw does not work for protocol #4 and #41. * The code will let you match protocol via src/dst address pair. */ /* XXX is M_NETADDR correct? */ #include "opt_mrouting.h" #include "opt_inet.h" #include "opt_inet6.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #include #include #endif #include #include #include #include static MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure"); static void encap_add __P((struct encaptab *)); static int mask_match __P((const struct encaptab *, const struct sockaddr *, const struct sockaddr *)); static void encap_fillarg __P((struct mbuf *, const struct encaptab *)); #ifndef LIST_HEAD_INITIALIZER /* rely upon BSS initialization */ LIST_HEAD(, encaptab) encaptab; #else LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab); #endif void encap_init() { static int initialized = 0; if (initialized) return; initialized++; #if 0 /* * we cannot use LIST_INIT() here, since drivers may want to call * encap_attach(), on driver attach. encap_init() will be called * on AF_INET{,6} initialization, which happens after driver * initialization - using LIST_INIT() here can nuke encap_attach() * from drivers. */ LIST_INIT(&encaptab); #endif } #ifdef INET void #if __STDC__ encap4_input(struct mbuf *m, ...) #else encap4_input(m, va_alist) struct mbuf *m; va_dcl #endif { int off, proto; struct ip *ip; struct sockaddr_in s, d; const struct ipprotosw *psw; struct encaptab *ep, *match; va_list ap; int prio, matchprio; va_start(ap, m); off = va_arg(ap, int); proto = va_arg(ap, int); va_end(ap); ip = mtod(m, struct ip *); bzero(&s, sizeof(s)); s.sin_family = AF_INET; s.sin_len = sizeof(struct sockaddr_in); s.sin_addr = ip->ip_src; bzero(&d, sizeof(d)); d.sin_family = AF_INET; d.sin_len = sizeof(struct sockaddr_in); d.sin_addr = ip->ip_dst; match = NULL; matchprio = 0; LIST_FOREACH(ep, &encaptab, chain) { if (ep->af != AF_INET) continue; if (ep->proto >= 0 && ep->proto != proto) continue; if (ep->func) prio = (*ep->func)(m, off, proto, ep->arg); else { /* * it's inbound traffic, we need to match in reverse * order */ prio = mask_match(ep, (struct sockaddr *)&d, (struct sockaddr *)&s); } /* * We prioritize the matches by using bit length of the * matches. mask_match() and user-supplied matching function * should return the bit length of the matches (for example, * if both src/dst are matched for IPv4, 64 should be returned). * 0 or negative return value means "it did not match". * * The question is, since we have two "mask" portion, we * cannot really define total order between entries. * For example, which of these should be preferred? * mask_match() returns 48 (32 + 16) for both of them. * src=3ffe::/16, dst=3ffe:501::/32 * src=3ffe:501::/32, dst=3ffe::/16 * * We need to loop through all the possible candidates * to get the best match - the search takes O(n) for * n attachments (i.e. interfaces). */ if (prio <= 0) continue; if (prio > matchprio) { matchprio = prio; match = ep; } } if (match) { /* found a match, "match" has the best one */ psw = (const struct ipprotosw *)match->psw; if (psw && psw->pr_input) { encap_fillarg(m, match); (*psw->pr_input)(m, off, proto); } else m_freem(m); return; } /* last resort: inject to raw socket */ rip_input(m, off, proto); } #endif #ifdef INET6 int encap6_input(mp, offp, proto) struct mbuf **mp; int *offp; int proto; { struct mbuf *m = *mp; struct ip6_hdr *ip6; struct sockaddr_in6 s, d; const struct ip6protosw *psw; struct encaptab *ep, *match; int prio, matchprio; ip6 = mtod(m, struct ip6_hdr *); bzero(&s, sizeof(s)); s.sin6_family = AF_INET6; s.sin6_len = sizeof(struct sockaddr_in6); s.sin6_addr = ip6->ip6_src; bzero(&d, sizeof(d)); d.sin6_family = AF_INET6; d.sin6_len = sizeof(struct sockaddr_in6); d.sin6_addr = ip6->ip6_dst; match = NULL; matchprio = 0; LIST_FOREACH(ep, &encaptab, chain) { if (ep->af != AF_INET6) continue; if (ep->proto >= 0 && ep->proto != proto) continue; if (ep->func) prio = (*ep->func)(m, *offp, proto, ep->arg); else { /* * it's inbound traffic, we need to match in reverse * order */ prio = mask_match(ep, (struct sockaddr *)&d, (struct sockaddr *)&s); } /* see encap4_input() for issues here */ if (prio <= 0) continue; if (prio > matchprio) { matchprio = prio; match = ep; } } if (match) { /* found a match */ psw = (const struct ip6protosw *)match->psw; if (psw && psw->pr_input) { encap_fillarg(m, match); return (*psw->pr_input)(mp, offp, proto); } else { m_freem(m); return IPPROTO_DONE; } } /* last resort: inject to raw socket */ return rip6_input(mp, offp, proto); } #endif static void encap_add(ep) struct encaptab *ep; { LIST_INSERT_HEAD(&encaptab, ep, chain); } /* * sp (src ptr) is always my side, and dp (dst ptr) is always remote side. * length of mask (sm and dm) is assumed to be same as sp/dp. * Return value will be necessary as input (cookie) for encap_detach(). */ const struct encaptab * encap_attach(af, proto, sp, sm, dp, dm, psw, arg) int af; int proto; const struct sockaddr *sp, *sm; const struct sockaddr *dp, *dm; const struct protosw *psw; void *arg; { struct encaptab *ep; int error; int s; s = splnet(); /* sanity check on args */ if (sp->sa_len > sizeof(ep->src) || dp->sa_len > sizeof(ep->dst)) { error = EINVAL; goto fail; } if (sp->sa_len != dp->sa_len) { error = EINVAL; goto fail; } if (af != sp->sa_family || af != dp->sa_family) { error = EINVAL; goto fail; } /* check if anyone have already attached with exactly same config */ LIST_FOREACH(ep, &encaptab, chain) { if (ep->af != af) continue; if (ep->proto != proto) continue; if (ep->src.ss_len != sp->sa_len || bcmp(&ep->src, sp, sp->sa_len) != 0 || bcmp(&ep->srcmask, sm, sp->sa_len) != 0) continue; if (ep->dst.ss_len != dp->sa_len || bcmp(&ep->dst, dp, dp->sa_len) != 0 || bcmp(&ep->dstmask, dm, dp->sa_len) != 0) continue; error = EEXIST; goto fail; } ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/ if (ep == NULL) { error = ENOBUFS; goto fail; } bzero(ep, sizeof(*ep)); ep->af = af; ep->proto = proto; bcopy(sp, &ep->src, sp->sa_len); bcopy(sm, &ep->srcmask, sp->sa_len); bcopy(dp, &ep->dst, dp->sa_len); bcopy(dm, &ep->dstmask, dp->sa_len); ep->psw = psw; ep->arg = arg; encap_add(ep); error = 0; splx(s); return ep; fail: splx(s); return NULL; } const struct encaptab * encap_attach_func(af, proto, func, psw, arg) int af; int proto; int (*func) __P((const struct mbuf *, int, int, void *)); const struct protosw *psw; void *arg; { struct encaptab *ep; int error; int s; s = splnet(); /* sanity check on args */ if (!func) { error = EINVAL; goto fail; } ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT); /*XXX*/ if (ep == NULL) { error = ENOBUFS; goto fail; } bzero(ep, sizeof(*ep)); ep->af = af; ep->proto = proto; ep->func = func; ep->psw = psw; ep->arg = arg; encap_add(ep); error = 0; splx(s); return ep; fail: splx(s); return NULL; } int encap_detach(cookie) const struct encaptab *cookie; { const struct encaptab *ep = cookie; struct encaptab *p; LIST_FOREACH(p, &encaptab, chain) { if (p == ep) { LIST_REMOVE(p, chain); free(p, M_NETADDR); /*XXX*/ return 0; } } return EINVAL; } static int mask_match(ep, sp, dp) const struct encaptab *ep; const struct sockaddr *sp; const struct sockaddr *dp; { struct sockaddr_storage s; struct sockaddr_storage d; int i; const u_int8_t *p, *q; u_int8_t *r; int matchlen; if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d)) return 0; if (sp->sa_family != ep->af || dp->sa_family != ep->af) return 0; if (sp->sa_len != ep->src.ss_len || dp->sa_len != ep->dst.ss_len) return 0; matchlen = 0; p = (const u_int8_t *)sp; q = (const u_int8_t *)&ep->srcmask; r = (u_int8_t *)&s; for (i = 0 ; i < sp->sa_len; i++) { r[i] = p[i] & q[i]; /* XXX estimate */ matchlen += (q[i] ? 8 : 0); } p = (const u_int8_t *)dp; q = (const u_int8_t *)&ep->dstmask; r = (u_int8_t *)&d; for (i = 0 ; i < dp->sa_len; i++) { r[i] = p[i] & q[i]; /* XXX rough estimate */ matchlen += (q[i] ? 8 : 0); } /* need to overwrite len/family portion as we don't compare them */ s.ss_len = sp->sa_len; s.ss_family = sp->sa_family; d.ss_len = dp->sa_len; d.ss_family = dp->sa_family; if (bcmp(&s, &ep->src, ep->src.ss_len) == 0 && bcmp(&d, &ep->dst, ep->dst.ss_len) == 0) { return matchlen; } else return 0; } static void encap_fillarg(m, ep) struct mbuf *m; const struct encaptab *ep; { #if 0 m->m_pkthdr.aux = ep->arg; #else struct mbuf *n; n = m_aux_add(m, AF_INET, IPPROTO_IPV4); if (n) { *mtod(n, void **) = ep->arg; n->m_len = sizeof(void *); } #endif } void * encap_getarg(m) struct mbuf *m; { void *p; #if 0 p = m->m_pkthdr.aux; m->m_pkthdr.aux = NULL; return p; #else struct mbuf *n; p = NULL; n = m_aux_find(m, AF_INET, IPPROTO_IPV4); if (n) { if (n->m_len == sizeof(void *)) p = *mtod(n, void **); m_aux_delete(m, n); } return p; #endif }