/* $OpenBSD: fil.c,v 1.10 1997/06/23 19:03:47 kstailey Exp $ */ /* * (C)opyright 1993-1996 by Darren Reed. * * Redistribution and use in source and binary forms are permitted * provided that this notice is preserved and due credit is given * to the original author and the contributors. */ #if 0 #if !defined(lint) && defined(LIBC_SCCS) static char sccsid[] = "@(#)fil.c 1.36 6/5/96 (C) 1993-1996 Darren Reed"; static char rcsid[] = "$DRId: fil.c,v 2.0.1.10 1997/04/13 22:33:07 darrenr Exp $"; #endif #endif #include #include #include #include #include #if defined(_KERNEL) || defined(KERNEL) # include #else # include # include #endif #include #if !defined(__SVR4) && !defined(__svr4__) # include #else # include # include # include #endif #include #include #include #ifdef sun # include #endif #include #include #include #include #include #include #include #include #include #include "ip_fil_compat.h" #include "ip_fil.h" #include "ip_nat.h" #include "ip_frag.h" #include "ip_state.h" #ifndef MIN #define MIN(a,b) (((a)<(b))?(a):(b)) #endif #ifndef _KERNEL #include "ipf.h" extern int opts; extern void debug(), verbose(); #define FR_IFVERBOSE(ex,second,verb_pr) if (ex) { verbose verb_pr; second; } #define FR_IFDEBUG(ex,second,verb_pr) if (ex) { debug verb_pr; second; } #define FR_VERBOSE(verb_pr) verbose verb_pr #define FR_DEBUG(verb_pr) debug verb_pr #define FR_SCANLIST(p, ip, fi, m) fr_scanlist(p, ip, fi, NULL) # if SOLARIS # define bcmp memcmp # endif #else #define FR_IFVERBOSE(ex,second,verb_pr) ; #define FR_IFDEBUG(ex,second,verb_pr) ; #define FR_VERBOSE(verb_pr) #define FR_DEBUG(verb_pr) #define FR_SCANLIST(p, ip, fi, m) fr_scanlist(p, ip, fi, m) extern int send_reset __P((struct tcpiphdr *)); # if SOLARIS extern int icmp_error(), ipfr_fastroute(); extern kmutex_t ipf_mutex, ipl_mutex; # else extern void ipfr_fastroute __P((struct mbuf *, fr_info_t *, frdest_t *)); # endif extern int ipl_unreach; extern int ipllog __P((u_int, ip_t *, register fr_info_t *, struct mbuf *)); #endif #if SOLARIS # define SEND_RESET(ip, if, q) send_reset(ip, qif, q) # define ICMP_ERROR(b, ip, t, c, if, src) \ icmp_error(b, ip, t, c, if, src) #else # define SEND_RESET(ip, if, q) send_reset( \ (struct tcpiphdr *)ip) # if BSD < 199103 # define ICMP_ERROR(b, ip, t, c, if, src) \ icmp_error(mtod(b, ip_t *), t, c, if, src) # else # define ICMP_ERROR(b, ip, t, c, if, src) \ icmp_error(b, t, c, (src).s_addr, if) # endif #endif #ifndef IPF_LOGGING #define IPF_LOGGING 0 #endif #ifdef IPF_DEFAULT_PASS #define IPF_NOMATCH (IPF_DEFAULT_PASS|FR_NOMATCH) #else #define IPF_NOMATCH (FR_PASS|FR_NOMATCH) #endif struct filterstats frstats[2] = {{0,0,0,0,0},{0,0,0,0,0}}; struct frentry *ipfilter[2][2] = { { NULL, NULL }, { NULL, NULL } }, *ipacct[2][2] = { { NULL, NULL }, { NULL, NULL } }; int fr_flags = IPF_LOGGING, fr_active = 0; fr_info_t frcache[2]; void fr_makefrip __P((int, ip_t *, fr_info_t *)); int fr_tcpudpchk __P((frentry_t *, fr_info_t *)); int fr_scanlist __P((int, ip_t *, fr_info_t *, void *m)); /* * bit values for identifying presence of individual IP options */ struct optlist ipopts[20] = { { IPOPT_NOP, 0x000001 }, { IPOPT_RR, 0x000002 }, { IPOPT_ZSU, 0x000004 }, { IPOPT_MTUP, 0x000008 }, { IPOPT_MTUR, 0x000010 }, { IPOPT_ENCODE, 0x000020 }, { IPOPT_TS, 0x000040 }, { IPOPT_TR, 0x000080 }, { IPOPT_SECURITY, 0x000100 }, { IPOPT_LSRR, 0x000200 }, { IPOPT_E_SEC, 0x000400 }, { IPOPT_CIPSO, 0x000800 }, { IPOPT_SATID, 0x001000 }, { IPOPT_SSRR, 0x002000 }, { IPOPT_ADDEXT, 0x004000 }, { IPOPT_VISA, 0x008000 }, { IPOPT_IMITD, 0x010000 }, { IPOPT_EIP, 0x020000 }, { IPOPT_FINN, 0x040000 }, { 0, 0x000000 } }; /* * bit values for identifying presence of individual IP security options */ struct optlist secopt[8] = { { IPSO_CLASS_RES4, 0x01 }, { IPSO_CLASS_TOPS, 0x02 }, { IPSO_CLASS_SECR, 0x04 }, { IPSO_CLASS_RES3, 0x08 }, { IPSO_CLASS_CONF, 0x10 }, { IPSO_CLASS_UNCL, 0x20 }, { IPSO_CLASS_RES2, 0x40 }, { IPSO_CLASS_RES1, 0x80 } }; /* * compact the IP header into a structure which contains just the info. * which is useful for comparing IP headers with. */ void fr_makefrip(hlen, ip, fin) int hlen; ip_t *ip; fr_info_t *fin; { struct optlist *op; tcphdr_t *tcp; fr_ip_t *fi = &fin->fin_fi; u_short optmsk = 0, secmsk = 0, auth = 0; int i, mv, ol, off; u_char *s, opt; fin->fin_fr = NULL; fin->fin_tcpf = 0; fin->fin_data[0] = 0; fin->fin_data[1] = 0; fin->fin_rule = -1; #ifdef _KERNEL fin->fin_icode = ipl_unreach; #endif fi->fi_v = ip->ip_v; fi->fi_tos = ip->ip_tos; fin->fin_hlen = hlen; fin->fin_dlen = ip->ip_len - hlen; tcp = (tcphdr_t *)((char *)ip + hlen); fin->fin_dp = (void *)tcp; (*(((u_short *)fi) + 1)) = (*(((u_short *)ip) + 4)); (*(((u_int32_t *)fi) + 1)) = (*(((u_int32_t *)ip) + 3)); (*(((u_int32_t *)fi) + 2)) = (*(((u_int32_t *)ip) + 4)); fi->fi_fl = (hlen > sizeof(struct ip)) ? FI_OPTIONS : 0; off = (ip->ip_off & 0x1fff) << 3; if (ip->ip_off & 0x3fff) fi->fi_fl |= FI_FRAG; switch (ip->ip_p) { case IPPROTO_ICMP : if ((!IPMINLEN(ip, icmp) && !off) || (off && off < sizeof(struct icmp))) fi->fi_fl |= FI_SHORT; if (fin->fin_dlen > 1) fin->fin_data[0] = *(u_short *)tcp; break; case IPPROTO_TCP : fi->fi_fl |= FI_TCPUDP; if ((!IPMINLEN(ip, tcphdr) && !off) || (off && off < sizeof(struct tcphdr))) fi->fi_fl |= FI_SHORT; if (!(fi->fi_fl & FI_SHORT) && !off) fin->fin_tcpf = tcp->th_flags; goto getports; case IPPROTO_UDP : fi->fi_fl |= FI_TCPUDP; if ((!IPMINLEN(ip, udphdr) && !off) || (off && off < sizeof(struct udphdr))) fi->fi_fl |= FI_SHORT; getports: if (!off && (fin->fin_dlen > 3)) { fin->fin_data[0] = ntohs(tcp->th_sport); fin->fin_data[1] = ntohs(tcp->th_dport); } break; default : break; } for (s = (u_char *)(ip + 1), hlen -= sizeof(*ip); hlen; ) { if (!(opt = *s)) break; ol = (opt == IPOPT_NOP) ? 1 : (int)*(s+1); if (opt > 1 && (ol < 2 || ol > hlen)) break; for (i = 9, mv = 4; mv >= 0; ) { op = ipopts + i; if (opt == (u_char)op->ol_val) { optmsk |= op->ol_bit; if (opt == IPOPT_SECURITY) { struct optlist *sp; u_char sec; int j, m; sec = *(s + 2); /* classification */ for (j = 3, m = 2; m >= 0; ) { sp = secopt + j; if (sec == sp->ol_val) { secmsk |= sp->ol_bit; auth = *(s + 3); auth *= 256; auth += *(s + 4); break; } if (sec < sp->ol_val) j -= m--; else j += m--; } } break; } if (opt < op->ol_val) i -= mv--; else i += mv--; } hlen -= ol; s += ol; } if (auth && !(auth & 0x0100)) auth &= 0xff00; fi->fi_optmsk = optmsk; fi->fi_secmsk = secmsk; fi->fi_auth = auth; } /* * check an IP packet for TCP/UDP characteristics such as ports and flags. */ int fr_tcpudpchk(fr, fin) frentry_t *fr; fr_info_t *fin; { register u_short po, tup; register char i; register int err = 1; /* * Both ports should *always* be in the first fragment. * So far, I cannot find any cases where they can not be. * * compare destination ports */ if ((i = (int)fr->fr_dcmp)) { po = fr->fr_dport; tup = fin->fin_data[1]; /* * Do opposite test to that required and * continue if that succeeds. */ if (!--i && tup != po) /* EQUAL */ err = 0; else if (!--i && tup == po) /* NOTEQUAL */ err = 0; else if (!--i && tup >= po) /* LESSTHAN */ err = 0; else if (!--i && tup <= po) /* GREATERTHAN */ err = 0; else if (!--i && tup > po) /* LT or EQ */ err = 0; else if (!--i && tup < po) /* GT or EQ */ err = 0; else if (!--i && /* Out of range */ (tup >= po && tup <= fr->fr_dtop)) err = 0; else if (!--i && /* In range */ (tup <= po || tup >= fr->fr_dtop)) err = 0; } /* * compare source ports */ if (err && (i = (int)fr->fr_scmp)) { po = fr->fr_sport; tup = fin->fin_data[0]; if (!--i && tup != po) err = 0; else if (!--i && tup == po) err = 0; else if (!--i && tup >= po) err = 0; else if (!--i && tup <= po) err = 0; else if (!--i && tup > po) err = 0; else if (!--i && tup < po) err = 0; else if (!--i && /* Out of range */ (tup >= po && tup <= fr->fr_stop)) err = 0; else if (!--i && /* In range */ (tup <= po || tup >= fr->fr_stop)) err = 0; } /* * If we don't have all the TCP/UDP header, then how can we * expect to do any sort of match on it ? If we were looking for * TCP flags, then NO match. If not, then match (which should * satisfy the "short" class too). */ if (err && (fin->fin_fi.fi_p == IPPROTO_TCP)) { if (fin->fin_fi.fi_fl & FI_SHORT) return !(fr->fr_tcpf | fr->fr_tcpfm); /* * Match the flags ? If not, abort this match. */ if (fr->fr_tcpf && fr->fr_tcpf != (fin->fin_tcpf & fr->fr_tcpfm)) { FR_DEBUG(("f. %#x & %#x != %#x\n", fin->fin_tcpf, fr->fr_tcpfm, fr->fr_tcpf)); err = 0; } } return err; } /* * Check the input/output list of rules for a match and result. * Could be per interface, but this gets real nasty when you don't have * kernel sauce. */ int fr_scanlist(pass, ip, fin, m) int pass; ip_t *ip; register fr_info_t *fin; void *m; { register struct frentry *fr; register fr_ip_t *fi = &fin->fin_fi; int rulen, portcmp = 0, off; fr = fin->fin_fr; fin->fin_fr = NULL; fin->fin_rule = 0; off = ip->ip_off & 0x1fff; pass |= (fi->fi_fl << 20); if ((fi->fi_fl & FI_TCPUDP) && (fin->fin_dlen > 3) && !off) portcmp = 1; for (rulen = 0; fr; fr = fr->fr_next, rulen++) { /* * In all checks below, a null (zero) value in the * filter struture is taken to mean a wildcard. * * check that we are working for the right interface */ #ifdef _KERNEL if (fr->fr_ifa && fr->fr_ifa != fin->fin_ifp) continue; #else if (opts & (OPT_VERBOSE|OPT_DEBUG)) printf("\n"); FR_VERBOSE(("%c", (pass & FR_PASS) ? 'p' : 'b')); if (fin->fin_ifp && *fr->fr_ifname && strcasecmp((char *)fin->fin_ifp, fr->fr_ifname)) continue; FR_VERBOSE((":i")); #endif { register u_long *ld, *lm, *lip; register int i; lip = (u_long *)fi; lm = (u_long *)&fr->fr_mip; ld = (u_long *)&fr->fr_ip; i = ((lip[0] & lm[0]) != ld[0]); FR_IFDEBUG(i,continue,("0. %#08x & %#08x != %#08x\n", lip[0], lm[0], ld[0])); i |= ((lip[1] & lm[1]) != ld[1]); FR_IFDEBUG(i,continue,("1. %#08x & %#08x != %#08x\n", lip[1], lm[1], ld[1])); i |= ((lip[2] & lm[2]) != ld[2]); FR_IFDEBUG(i,continue,("2. %#08x & %#08x != %#08x\n", lip[2], lm[2], ld[2])); i |= ((lip[3] & lm[3]) != ld[3]); FR_IFDEBUG(i,continue,("3. %#08x & %#08x != %#08x\n", lip[3], lm[3], ld[3])); i |= ((lip[4] & lm[4]) != ld[4]); FR_IFDEBUG(i,continue,("4. %#08x & %#08x != %#08x\n", lip[4], lm[4], ld[4])); if (i) continue; } /* * If a fragment, then only the first has what we're looking * for here... */ if (fi->fi_fl & FI_TCPUDP) { if (portcmp) { if (!fr_tcpudpchk(fr, fin)) continue; } else if (fr->fr_dcmp || fr->fr_scmp || fr->fr_tcpf || fr->fr_tcpfm) continue; } else if (fi->fi_p == IPPROTO_ICMP) { if (!off && (fin->fin_dlen > 1)) { if ((fin->fin_data[0] & fr->fr_icmpm) != fr->fr_icmp) { FR_DEBUG(("i. %#x & %#x != %#x\n", fin->fin_data[0], fr->fr_icmpm, fr->fr_icmp)); continue; } } else if (fr->fr_icmpm || fr->fr_icmp) continue; } FR_VERBOSE(("*")); /* * Just log this packet... */ pass = fr->fr_flags; if ((pass & FR_CALLNOW) && fr->fr_func) pass = (*fr->fr_func)(pass, ip, fin); #ifdef IPFILTER_LOG if ((pass & FR_LOGMASK) == FR_LOG) { if (!ipllog(fr->fr_flags, ip, fin, m)) frstats[fin->fin_out].fr_skip++; frstats[fin->fin_out].fr_pkl++; } #endif /* IPFILTER_LOG */ FR_DEBUG(("pass %#x\n", pass)); fr->fr_hits++; if (pass & FR_ACCOUNT) fr->fr_bytes += ip->ip_len; else fin->fin_icode = fr->fr_icode; fin->fin_rule = rulen; fin->fin_fr = fr; if (pass & FR_QUICK) break; } return pass; } /* * frcheck - filter check * check using source and destination addresses/ports in a packet whether * or not to pass it on or not. */ int fr_check(ip, hlen, ifp, out #ifdef _KERNEL # if SOLARIS , qif, q, mp) qif_t *qif; queue_t *q; mblk_t **mp; # else , mp) struct mbuf **mp; # endif #else ) #endif ip_t *ip; int hlen; struct ifnet *ifp; int out; { /* * The above really sucks, but short of writing a diff */ fr_info_t frinfo, *fc; register fr_info_t *fin = &frinfo; frentry_t *fr = NULL; int pass, changed; #if !defined(__SVR4) && !defined(__svr4__) && defined(_KERNEL) register struct mbuf *m = *mp; struct mbuf *mc = NULL; if ((ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_UDP || ip->ip_p == IPPROTO_ICMP)) { register int up = MIN(hlen + 8, ip->ip_len); if (up > m->m_len) { if ((*mp = m_pullup(m, up)) == 0) { frstats[out].fr_pull[1]++; return -1; } else { frstats[out].fr_pull[0]++; m = *mp; ip = mtod(m, struct ip *); } } } #endif #if SOLARIS && defined(_KERNEL) mblk_t *mc = NULL, *m = qif->qf_m; #endif fr_makefrip(hlen, ip, fin); fin->fin_ifp = ifp; fin->fin_out = out; MUTEX_ENTER(&ipf_mutex); if (!out) { changed = ip_natin(ip, hlen, fin); if ((fin->fin_fr = ipacct[0][fr_active]) && (FR_SCANLIST(FR_NOMATCH, ip, fin, m) & FR_ACCOUNT)) frstats[0].fr_acct++; } if ((pass = ipfr_knownfrag(ip, fin))) { if ((pass & FR_KEEPSTATE)) { if (fr_addstate(ip, fin, pass) == -1) frstats[out].fr_bads++; else frstats[out].fr_ads++; } } else if ((pass = fr_checkstate(ip, fin))) { if ((pass & FR_KEEPFRAG)) { if (fin->fin_fi.fi_fl & FI_FRAG) { if (ipfr_newfrag(ip, fin, pass) == -1) frstats[out].fr_bnfr++; else frstats[out].fr_nfr++; } else frstats[out].fr_cfr++; } } else { fc = frcache + out; if (fc->fin_fr && !bcmp((char *)fin, (char *)fc, FI_CSIZE)) { /* * copy cached data so we can unlock the mutex * earlier. */ bcopy((char *)fc, (char *)fin, sizeof(*fin)); frstats[out].fr_chit++; pass = fin->fin_fr->fr_flags; } else { pass = IPF_NOMATCH; if ((fin->fin_fr = ipfilter[out][fr_active])) pass = FR_SCANLIST(IPF_NOMATCH, ip, fin, m); bcopy((char *)fin, (char *)fc, FI_CSIZE); if (pass & FR_NOMATCH) frstats[out].fr_nom++; } fr = fin->fin_fr; if ((pass & FR_KEEPFRAG)) { if (fin->fin_fi.fi_fl & FI_FRAG) { if (ipfr_newfrag(ip, fin, pass) == -1) frstats[out].fr_bnfr++; else frstats[out].fr_nfr++; } else frstats[out].fr_cfr++; } if (pass & FR_KEEPSTATE) { if (fr_addstate(ip, fin, pass) == -1) frstats[out].fr_bads++; else frstats[out].fr_ads++; } } if (fr && fr->fr_func && !(pass & FR_CALLNOW)) pass = (*fr->fr_func)(pass, ip, fin); if (out) { if ((fin->fin_fr = ipacct[1][fr_active]) && (FR_SCANLIST(FR_NOMATCH, ip, fin, m) & FR_ACCOUNT)) frstats[1].fr_acct++; fin->fin_fr = NULL; changed = ip_natout(ip, hlen, fin); } fin->fin_fr = fr; MUTEX_EXIT(&ipf_mutex); #ifdef IPFILTER_LOG if ((fr_flags & FF_LOGGING) || (pass & FR_LOGMASK)) { if ((fr_flags & FF_LOGNOMATCH) && (pass & FR_NOMATCH)) { pass |= FF_LOGNOMATCH; frstats[out].fr_npkl++; goto logit; } else if (((pass & FR_LOGMASK) == FR_LOGP) || ((pass & FR_PASS) && (fr_flags & FF_LOGPASS))) { if ((pass & FR_LOGMASK) != FR_LOGP) pass |= FF_LOGPASS; frstats[out].fr_ppkl++; goto logit; } else if (((pass & FR_LOGMASK) == FR_LOGB) || ((pass & FR_BLOCK) && (fr_flags & FF_LOGBLOCK))) { if ((pass & FR_LOGMASK) != FR_LOGB) pass |= FF_LOGBLOCK; frstats[out].fr_bpkl++; logit: if (!ipllog(pass, ip, fin, m)) { frstats[out].fr_skip++; if ((pass & (FR_PASS|FR_LOGORBLOCK)) == (FR_PASS|FR_LOGORBLOCK)) pass ^= FR_PASS|FR_BLOCK; } } } #endif /* IPFILTER_LOG */ #ifdef _KERNEL if (fr && (pass & FR_DUP)) # if SOLARIS mc = dupmsg(m); # else mc = m_copy(m, 0, M_COPYALL); # endif #endif if (pass & FR_PASS) frstats[out].fr_pass++; else if (pass & FR_BLOCK) { frstats[out].fr_block++; /* * Should we return an ICMP packet to indicate error * status passing through the packet filter ? * WARNING: ICMP error packets AND TCP RST packets should * ONLY be sent in repsonse to incoming packets. Sending them * in response to outbound packets can result in a panic on * some operating systems. */ if (!out) { #ifdef _KERNEL if (pass & FR_RETICMP) { # if SOLARIS ICMP_ERROR(q, ip, ICMP_UNREACH, fin->fin_icode, qif, ip->ip_src); # else ICMP_ERROR(m, ip, ICMP_UNREACH, fin->fin_icode, ifp, ip->ip_src); m = *mp = NULL; /* freed by icmp_error() */ # endif frstats[0].fr_ret++; } else if ((pass & FR_RETRST) && !(fin->fin_fi.fi_fl & FI_SHORT)) { if (SEND_RESET(ip, qif, q) == 0) frstats[1].fr_ret++; } #else if (pass & FR_RETICMP) { verbose("- ICMP unreachable sent\n"); frstats[0].fr_ret++; } else if ((pass & FR_RETRST) && !(fin->fin_fi.fi_fl & FI_SHORT)) { verbose("- TCP RST sent\n"); frstats[1].fr_ret++; } #endif } } #ifdef _KERNEL # if !SOLARIS if (fr) { frdest_t *fdp = &fr->fr_tif; if ((pass & FR_FASTROUTE) || (fdp->fd_ifp && fdp->fd_ifp != (struct ifnet *)-1)) { ipfr_fastroute(m, fin, fdp); m = *mp = NULL; } if (mc) ipfr_fastroute(mc, fin, &fr->fr_dif); } if (!(pass & FR_PASS) && m) m_freem(m); return (pass & FR_PASS) ? 0 : -1; # else if (fr) { frdest_t *fdp = &fr->fr_tif; if ((pass & FR_FASTROUTE) || (fdp->fd_ifp && fdp->fd_ifp != (struct ifnet *)-1)) { ipfr_fastroute(qif, ip, m, mp, fin, fdp); m = *mp = NULL; } if (mc) ipfr_fastroute(qif, ip, mc, mp, fin, &fr->fr_dif); } return (pass & FR_PASS) ? changed : -1; # endif #else if (pass & FR_NOMATCH) return 1; if (pass & FR_PASS) return 0; return -1; #endif } #ifdef IPFILTER_LOG # if !(defined(_KERNEL)) static void ipllog() { verbose("l"); } # endif int fr_copytolog(buf, len) char *buf; int len; { int clen, tail; tail = (iplh >= iplt) ? (iplbuf + IPLLOGSIZE - iplh) : (iplt - iplh); clen = MIN(tail, len); bcopy(buf, iplh, clen); len -= clen; tail -= clen; iplh += clen; buf += clen; if (iplh == iplbuf + IPLLOGSIZE) { iplh = iplbuf; tail = iplt - iplh; } if (len && tail) { clen = MIN(tail, len); bcopy(buf, iplh, clen); len -= clen; iplh += clen; } return len; } #endif