/* * PPP IP Protocol Interface * * Written by Toshiharu OHNO (tony-o@iij.ad.jp) * * Copyright (C) 1993, Internet Initiative Japan, Inc. All rights reserverd. * * Redistribution and use in source and binary forms are permitted * provided that the above copyright notice and this paragraph are * duplicated in all such forms and that any documentation, * advertising materials, and other materials related to such * distribution and use acknowledge that the software was developed * by the Internet Initiative Japan. The name of the * IIJ may not be used to endorse or promote products derived * from this software without specific prior written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. * * $Id: ip.c,v 1.67 1999/08/02 15:29:19 brian Exp $ * * TODO: * o Return ICMP message for filterd packet * and optionaly record it into log. */ #include #if defined(__OpenBSD__) || defined(__NetBSD__) #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include "layer.h" #include "proto.h" #include "mbuf.h" #include "log.h" #include "defs.h" #include "timer.h" #include "fsm.h" #include "lqr.h" #include "hdlc.h" #include "throughput.h" #include "iplist.h" #include "slcompress.h" #include "ipcp.h" #include "filter.h" #include "descriptor.h" #include "lcp.h" #include "ccp.h" #include "link.h" #include "mp.h" #ifndef NORADIUS #include "radius.h" #endif #include "bundle.h" #include "tun.h" #include "ip.h" static const u_short interactive_ports[32] = { 544, 513, 514, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 80, 81, 0, 0, 0, 21, 22, 23, 0, 0, 0, 0, 0, 0, 0, 543, }; #define INTERACTIVE(p) (interactive_ports[(p) & 0x1F] == (p)) static const char *TcpFlags[] = { "FIN", "SYN", "RST", "PSH", "ACK", "URG" }; static __inline int PortMatch(int op, u_short pport, u_short rport) { switch (op) { case OP_EQ: return (pport == rport); case OP_GT: return (pport > rport); case OP_LT: return (pport < rport); default: return (0); } } /* * Check a packet against a defined filter * Returns 0 to accept the packet, non-zero to drop the packet * * If filtering is enabled, the initial fragment of a datagram must * contain the complete protocol header, and subsequent fragments * must not attempt to over-write it. */ static int FilterCheck(const struct ip *pip, const struct filter *filter) { int gotinfo; /* true if IP payload decoded */ int cproto; /* P_* protocol type if (gotinfo) */ int estab, syn, finrst; /* TCP state flags if (gotinfo) */ u_short sport, dport; /* src, dest port from packet if (gotinfo) */ int n; /* filter rule to process */ int len; /* bytes used in dbuff */ int didname; /* true if filter header printed */ int match; /* true if condition matched */ const struct filterent *fp = filter->rule; char dbuff[100]; if (fp->f_action == A_NONE) return (0); /* No rule is given. Permit this packet */ /* Deny any packet fragment that tries to over-write the header. * Since we no longer have the real header available, punt on the * largest normal header - 20 bytes for TCP without options, rounded * up to the next possible fragment boundary. Since the smallest * `legal' MTU is 576, and the smallest recommended MTU is 296, any * fragmentation within this range is dubious at best */ len = ntohs(pip->ip_off) & IP_OFFMASK; /* fragment offset */ if (len > 0) { /* Not first fragment within datagram */ if (len < (24 >> 3)) /* don't allow fragment to over-write header */ return (1); /* permit fragments on in and out filter */ return (filter->fragok); } cproto = gotinfo = estab = syn = finrst = didname = 0; sport = dport = 0; for (n = 0; n < MAXFILTERS; ) { if (fp->f_action == A_NONE) { n++; fp++; continue; } if (!didname) { log_Printf(LogDEBUG, "%s filter:\n", filter->name); didname = 1; } match = 0; if (!((pip->ip_src.s_addr ^ fp->f_src.ipaddr.s_addr) & fp->f_src.mask.s_addr) && !((pip->ip_dst.s_addr ^ fp->f_dst.ipaddr.s_addr) & fp->f_dst.mask.s_addr)) { if (fp->f_proto != P_NONE) { if (!gotinfo) { const char *ptop = (const char *) pip + (pip->ip_hl << 2); const struct tcphdr *th; const struct udphdr *uh; const struct icmp *ih; int datalen; /* IP datagram length */ datalen = ntohs(pip->ip_len) - (pip->ip_hl << 2); switch (pip->ip_p) { case IPPROTO_ICMP: cproto = P_ICMP; if (datalen < 8) /* ICMP must be at least 8 octets */ return (1); ih = (const struct icmp *) ptop; sport = ih->icmp_type; estab = syn = finrst = -1; if (log_IsKept(LogDEBUG)) snprintf(dbuff, sizeof dbuff, "sport = %d", sport); break; case IPPROTO_IGMP: cproto = P_IGMP; if (datalen < 8) /* IGMP uses 8-octet messages */ return (1); estab = syn = finrst = -1; sport = ntohs(0); break; #ifdef IPPROTO_OSPFIGP case IPPROTO_OSPFIGP: cproto = P_OSPF; if (datalen < 8) /* IGMP uses 8-octet messages */ return (1); estab = syn = finrst = -1; sport = ntohs(0); break; #endif case IPPROTO_UDP: case IPPROTO_IPIP: cproto = P_UDP; if (datalen < 8) /* UDP header is 8 octets */ return (1); uh = (const struct udphdr *) ptop; sport = ntohs(uh->uh_sport); dport = ntohs(uh->uh_dport); estab = syn = finrst = -1; if (log_IsKept(LogDEBUG)) snprintf(dbuff, sizeof dbuff, "sport = %d, dport = %d", sport, dport); break; case IPPROTO_TCP: cproto = P_TCP; th = (const struct tcphdr *) ptop; /* TCP headers are variable length. The following code * ensures that the TCP header length isn't de-referenced if * the datagram is too short */ if (datalen < 20 || datalen < (th->th_off << 2)) return (1); sport = ntohs(th->th_sport); dport = ntohs(th->th_dport); estab = (th->th_flags & TH_ACK); syn = (th->th_flags & TH_SYN); finrst = (th->th_flags & (TH_FIN|TH_RST)); if (log_IsKept(LogDEBUG)) { if (!estab) snprintf(dbuff, sizeof dbuff, "flags = %02x, sport = %d, dport = %d", th->th_flags, sport, dport); else *dbuff = '\0'; } break; default: return (1); /* We'll block unknown type of packet */ } if (log_IsKept(LogDEBUG)) { if (estab != -1) { len = strlen(dbuff); snprintf(dbuff + len, sizeof dbuff - len, ", estab = %d, syn = %d, finrst = %d", estab, syn, finrst); } log_Printf(LogDEBUG, " Filter: proto = %s, %s\n", filter_Proto2Nam(cproto), dbuff); } gotinfo = 1; } if (log_IsKept(LogDEBUG)) { if (fp->f_srcop != OP_NONE) { snprintf(dbuff, sizeof dbuff, ", src %s %d", filter_Op2Nam(fp->f_srcop), fp->f_srcport); len = strlen(dbuff); } else len = 0; if (fp->f_dstop != OP_NONE) { snprintf(dbuff + len, sizeof dbuff - len, ", dst %s %d", filter_Op2Nam(fp->f_dstop), fp->f_dstport); } else if (!len) *dbuff = '\0'; log_Printf(LogDEBUG, " rule = %d: Address match, " "check against proto %s%s, action = %s\n", n, filter_Proto2Nam(fp->f_proto), dbuff, filter_Action2Nam(fp->f_action)); } if (cproto == fp->f_proto) { if ((fp->f_srcop == OP_NONE || PortMatch(fp->f_srcop, sport, fp->f_srcport)) && (fp->f_dstop == OP_NONE || PortMatch(fp->f_dstop, dport, fp->f_dstport)) && (fp->f_estab == 0 || estab) && (fp->f_syn == 0 || syn) && (fp->f_finrst == 0 || finrst)) { match = 1; } } } else { /* Address is matched and no protocol specified. Make a decision. */ log_Printf(LogDEBUG, " rule = %d: Address match, action = %s\n", n, filter_Action2Nam(fp->f_action)); match = 1; } } else log_Printf(LogDEBUG, " rule = %d: Address mismatch\n", n); if (match != fp->f_invert) { /* Take specified action */ if (fp->f_action < A_NONE) fp = &filter->rule[n = fp->f_action]; else return (fp->f_action != A_PERMIT); } else { n++; fp++; } } return (1); /* No rule is mached. Deny this packet */ } #ifdef notdef static void IcmpError(struct ip *pip, int code) { struct mbuf *bp; if (pip->ip_p != IPPROTO_ICMP) { bp = mbuf_Alloc(cnt, MB_IPIN); memcpy(MBUF_CTOP(bp), ptr, cnt); vj_SendFrame(bp); ipcp_AddOutOctets(cnt); } } #endif /* * For debugging aid. */ int PacketCheck(struct bundle *bundle, char *cp, int nb, struct filter *filter) { struct ip *pip; struct tcphdr *th; struct udphdr *uh; struct icmp *icmph; char *ptop; int mask, len, n; int pri = PRI_NORMAL; int logit, loglen; char logbuf[200]; logit = log_IsKept(LogTCPIP) && filter->logok; loglen = 0; pip = (struct ip *) cp; if (logit && loglen < sizeof logbuf) { snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s ", filter->name); loglen += strlen(logbuf + loglen); } ptop = (cp + (pip->ip_hl << 2)); switch (pip->ip_p) { case IPPROTO_ICMP: if (logit && loglen < sizeof logbuf) { icmph = (struct icmp *) ptop; snprintf(logbuf + loglen, sizeof logbuf - loglen, "ICMP: %s:%d ---> ", inet_ntoa(pip->ip_src), icmph->icmp_type); loglen += strlen(logbuf + loglen); snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s:%d", inet_ntoa(pip->ip_dst), icmph->icmp_type); loglen += strlen(logbuf + loglen); } break; case IPPROTO_UDP: if (logit && loglen < sizeof logbuf) { uh = (struct udphdr *) ptop; snprintf(logbuf + loglen, sizeof logbuf - loglen, "UDP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport)); loglen += strlen(logbuf + loglen); snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport)); loglen += strlen(logbuf + loglen); } break; #ifdef IPPROTO_OSPFIGP case IPPROTO_OSPFIGP: if (logit && loglen < sizeof logbuf) { snprintf(logbuf + loglen, sizeof logbuf - loglen, "OSPF: %s ---> ", inet_ntoa(pip->ip_src)); loglen += strlen(logbuf + loglen); snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s", inet_ntoa(pip->ip_dst)); loglen += strlen(logbuf + loglen); } break; #endif case IPPROTO_IPIP: if (logit && loglen < sizeof logbuf) { uh = (struct udphdr *) ptop; snprintf(logbuf + loglen, sizeof logbuf - loglen, "IPIP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport)); loglen += strlen(logbuf + loglen); snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport)); loglen += strlen(logbuf + loglen); } break; case IPPROTO_IGMP: if (logit && loglen < sizeof logbuf) { uh = (struct udphdr *) ptop; snprintf(logbuf + loglen, sizeof logbuf - loglen, "IGMP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport)); loglen += strlen(logbuf + loglen); snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport)); loglen += strlen(logbuf + loglen); } break; case IPPROTO_TCP: th = (struct tcphdr *) ptop; if (pip->ip_tos == IPTOS_LOWDELAY) pri = PRI_FAST; else if ((ntohs(pip->ip_off) & IP_OFFMASK) == 0) { if (INTERACTIVE(ntohs(th->th_sport)) || INTERACTIVE(ntohs(th->th_dport))) pri = PRI_FAST; } if (logit && loglen < sizeof logbuf) { len = ntohs(pip->ip_len) - (pip->ip_hl << 2) - (th->th_off << 2); snprintf(logbuf + loglen, sizeof logbuf - loglen, "TCP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(th->th_sport)); loglen += strlen(logbuf + loglen); snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s:%d", inet_ntoa(pip->ip_dst), ntohs(th->th_dport)); loglen += strlen(logbuf + loglen); n = 0; for (mask = TH_FIN; mask != 0x40; mask <<= 1) { if (th->th_flags & mask) { snprintf(logbuf + loglen, sizeof logbuf - loglen, " %s", TcpFlags[n]); loglen += strlen(logbuf + loglen); } n++; } snprintf(logbuf + loglen, sizeof logbuf - loglen, " seq:%lx ack:%lx (%d/%d)", (u_long)ntohl(th->th_seq), (u_long)ntohl(th->th_ack), len, nb); loglen += strlen(logbuf + loglen); if ((th->th_flags & TH_SYN) && nb > 40) { u_short *sp; ptop += 20; sp = (u_short *) ptop; if (ntohs(sp[0]) == 0x0204) { snprintf(logbuf + loglen, sizeof logbuf - loglen, " MSS = %d", ntohs(sp[1])); loglen += strlen(logbuf + loglen); } } } break; } if (FilterCheck(pip, filter)) { if (logit) log_Printf(LogTCPIP, "%s - BLOCKED\n", logbuf); #ifdef notdef if (direction == 0) IcmpError(pip, pri); #endif return (-1); } else { /* Check Keep Alive filter */ if (logit) { if (FilterCheck(pip, &bundle->filter.alive)) log_Printf(LogTCPIP, "%s - NO KEEPALIVE\n", logbuf); else log_Printf(LogTCPIP, "%s\n", logbuf); } return (pri); } } struct mbuf * ip_Input(struct bundle *bundle, struct link *l, struct mbuf *bp) { int nb, nw; struct tun_data tun; struct ip *pip; if (bundle->ncp.ipcp.fsm.state != ST_OPENED) { log_Printf(LogWARN, "ip_Input: IPCP not open - packet dropped\n"); mbuf_Free(bp); return NULL; } mbuf_SetType(bp, MB_IPIN); tun_fill_header(tun, AF_INET); nb = mbuf_Length(bp); if (nb > sizeof tun.data) { log_Printf(LogWARN, "ip_Input: %s: Packet too large (got %d, max %d)\n", l->name, nb, (int)(sizeof tun.data)); mbuf_Free(bp); return NULL; } mbuf_Read(bp, tun.data, nb); if (PacketCheck(bundle, tun.data, nb, &bundle->filter.in) < 0) return NULL; pip = (struct ip *)tun.data; if (!FilterCheck(pip, &bundle->filter.alive)) bundle_StartIdleTimer(bundle); ipcp_AddInOctets(&bundle->ncp.ipcp, nb); nb += sizeof tun - sizeof tun.data; nw = write(bundle->dev.fd, &tun, nb); if (nw != nb) { if (nw == -1) log_Printf(LogERROR, "ip_Input: %s: wrote %d, got %s\n", l->name, nb, strerror(errno)); else log_Printf(LogERROR, "ip_Input: %s: wrote %d, got %d\n", l->name, nb, nw); } return NULL; } void ip_Enqueue(struct ipcp *ipcp, int pri, char *ptr, int count) { struct mbuf *bp; if (pri < 0 || pri > sizeof ipcp->Queue / sizeof ipcp->Queue[0]) log_Printf(LogERROR, "Can't store in ip queue %d\n", pri); else { /* * We allocate an extra 6 bytes, four at the front and two at the end. * This is an optimisation so that we need to do less work in * mbuf_Prepend() in acf_LayerPush() and proto_LayerPush() and * appending in hdlc_LayerPush(). */ bp = mbuf_Alloc(count + 6, MB_IPOUT); bp->offset += 4; bp->cnt -= 6; memcpy(MBUF_CTOP(bp), ptr, count); mbuf_Enqueue(&ipcp->Queue[pri], bp); } } void ip_DeleteQueue(struct ipcp *ipcp) { struct mqueue *queue; for (queue = ipcp->Queue; queue < ipcp->Queue + PRI_MAX; queue++) while (queue->top) mbuf_Free(mbuf_Dequeue(queue)); } int ip_QueueLen(struct ipcp *ipcp) { struct mqueue *queue; int result = 0; for (queue = ipcp->Queue; queue < ipcp->Queue + PRI_MAX; queue++) result += queue->qlen; return result; } int ip_PushPacket(struct link *l, struct bundle *bundle) { struct ipcp *ipcp = &bundle->ncp.ipcp; struct mqueue *queue; struct mbuf *bp; struct ip *pip; int cnt; if (ipcp->fsm.state != ST_OPENED) return 0; for (queue = &ipcp->Queue[PRI_FAST]; queue >= ipcp->Queue; queue--) if (queue->top) { bp = mbuf_Contiguous(mbuf_Dequeue(queue)); cnt = mbuf_Length(bp); pip = (struct ip *)MBUF_CTOP(bp); if (!FilterCheck(pip, &bundle->filter.alive)) bundle_StartIdleTimer(bundle); link_PushPacket(l, bp, bundle, PRI_NORMAL, PROTO_IP); ipcp_AddOutOctets(ipcp, cnt); return 1; } return 0; }