/* $NetBSD: ip_proxy.c,v 1.36 2002/09/19 08:12:54 martti Exp $ */ /* * Copyright (C) 1997-2002 by Darren Reed. * * See the IPFILTER.LICENCE file for details on licencing. */ #if defined(__FreeBSD__) && defined(KERNEL) && !defined(_KERNEL) # define _KERNEL #endif #ifdef __sgi # include #endif #include #include #include #include #include #if !defined(__FreeBSD_version) # include #endif #include #if !defined(_KERNEL) && !defined(KERNEL) # include # include # include #endif #ifndef linux # include #endif #include #if defined(_KERNEL) # if !defined(linux) # include # else # include # endif #endif #if !defined(__SVR4) && !defined(__svr4__) # ifndef linux # include # endif #else # include # ifdef _KERNEL # include # endif # include # include #endif #if __FreeBSD__ > 2 # include #endif #include #ifdef sun # include #endif #include #include #include #include #ifndef linux # include #endif #include #include #include #include "netinet/ip_compat.h" #include #include "netinet/ip_fil.h" #include "netinet/ip_nat.h" #include "netinet/ip_state.h" #include "netinet/ip_proxy.h" #if (__FreeBSD_version >= 300000) # include #endif #if !defined(lint) #if defined(__NetBSD__) #include __KERNEL_RCSID(0, "$NetBSD: ip_proxy.c,v 1.36 2002/09/19 08:12:54 martti Exp $"); #else static const char rcsid[] = "@(#)Id: ip_proxy.c,v 2.9.2.24 2002/08/28 12:45:51 darrenr Exp"; #endif #endif #if defined(_KERNEL) && (SOLARIS || defined(__sgi)) extern KRWLOCK_T ipf_nat, ipf_state; #endif #ifndef MIN #define MIN(a,b) (((a)<(b))?(a):(b)) #endif static int appr_fixseqack __P((fr_info_t *, ip_t *, ap_session_t *, int )); #define PROXY_DEBUG 0 #define AP_SESS_SIZE 53 #include "netinet/ip_ftp_pxy.c" #if defined(_KERNEL) #include "netinet/ip_rcmd_pxy.c" #include "netinet/ip_raudio_pxy.c" #include "netinet/ip_netbios_pxy.c" #include "netinet/ip_h323_pxy.c" #endif #include "netinet/ip_ipsec_pxy.c" ap_session_t *ap_sess_tab[AP_SESS_SIZE]; ap_session_t *ap_sess_list = NULL; aproxy_t *ap_proxylist = NULL; aproxy_t ap_proxies[] = { #ifdef IPF_FTP_PROXY { NULL, "ftp", (char)IPPROTO_TCP, 0, 0, ippr_ftp_init, NULL, ippr_ftp_new, NULL, ippr_ftp_in, ippr_ftp_out, NULL }, #endif #ifdef IPF_RCMD_PROXY { NULL, "rcmd", (char)IPPROTO_TCP, 0, 0, ippr_rcmd_init, NULL, ippr_rcmd_new, NULL, NULL, ippr_rcmd_out, NULL }, #endif #ifdef IPF_RAUDIO_PROXY { NULL, "raudio", (char)IPPROTO_TCP, 0, 0, ippr_raudio_init, NULL, ippr_raudio_new, NULL, ippr_raudio_in, ippr_raudio_out, NULL }, #endif #ifdef IPF_IPSEC_PROXY { NULL, "ipsec", (char)IPPROTO_UDP, 0, 0, ippr_ipsec_init, NULL, ippr_ipsec_new, ippr_ipsec_del, NULL, ippr_ipsec_out, ippr_ipsec_match }, #endif #ifdef IPF_NETBIOS_PROXY { NULL, "netbios", (char)IPPROTO_UDP, 0, 0, ippr_netbios_init, NULL, NULL, NULL, NULL, ippr_netbios_out, NULL }, #endif #ifdef IPF_H323_PROXY { NULL, "h323", (char)IPPROTO_TCP, 0, 0, ippr_h323_init, NULL, ippr_h323_new, ippr_h323_del, ippr_h323_in, ippr_h323_out, NULL }, { NULL, "h245", (char)IPPROTO_TCP, 0, 0, ippr_h245_init, NULL, ippr_h245_new, NULL, NULL, ippr_h245_out, NULL }, #endif { NULL, "", '\0', 0, 0, NULL, NULL, NULL } }; /* * Dynamically add a new kernel proxy. Ensure that it is unique in the * collection compiled in and dynamically added. */ int appr_add(ap) aproxy_t *ap; { aproxy_t *a; for (a = ap_proxies; a->apr_p; a++) if ((a->apr_p == ap->apr_p) && !strncmp(a->apr_label, ap->apr_label, sizeof(ap->apr_label))) return -1; for (a = ap_proxylist; a && a->apr_p; a = a->apr_next) if ((a->apr_p == ap->apr_p) && !strncmp(a->apr_label, ap->apr_label, sizeof(ap->apr_label))) return -1; ap->apr_next = ap_proxylist; ap_proxylist = ap; return (*ap->apr_init)(); } /* * Delete a proxy that has been added dynamically from those available. * If it is in use, return 1 (do not destroy NOW), not in use 0 or -1 * if it cannot be matched. */ int appr_del(ap) aproxy_t *ap; { aproxy_t *a, **app; for (app = &ap_proxylist; (a = *app); app = &a->apr_next) if (a == ap) { a->apr_flags |= APR_DELETE; *app = a->apr_next; if (ap->apr_ref != 0) return 1; return 0; } return -1; } /* * Return 1 if the packet is a good match against a proxy, else 0. */ int appr_ok(ip, tcp, nat) ip_t *ip; tcphdr_t *tcp; ipnat_t *nat; { aproxy_t *apr = nat->in_apr; u_short dport = nat->in_dport; if ((apr == NULL) || (apr->apr_flags & APR_DELETE) || (ip->ip_p != apr->apr_p)) return 0; if (((tcp != NULL) && (tcp->th_dport != dport)) || (!tcp && dport)) return 0; return 1; } /* * If a proxy has a match function, call that to do extended packet * matching. */ int appr_match(fin, nat) fr_info_t *fin; nat_t *nat; { aproxy_t *apr; ipnat_t *ipn; ipn = nat->nat_ptr; if (ipn == NULL) return -1; apr = ipn->in_apr; if ((apr == NULL) || (apr->apr_flags & APR_DELETE) || (nat->nat_aps == NULL)) return -1; if (apr->apr_match != NULL) if ((*apr->apr_match)(fin, nat->nat_aps, nat) != 0) return -1; return 0; } /* * Allocate a new application proxy structure and fill it in with the * relevant details. call the init function once complete, prior to * returning. */ int appr_new(fin, ip, nat) fr_info_t *fin; ip_t *ip; nat_t *nat; { register ap_session_t *aps; aproxy_t *apr; if ((nat->nat_ptr == NULL) || (nat->nat_aps != NULL)) return -1; apr = nat->nat_ptr->in_apr; if (!apr || (apr->apr_flags & APR_DELETE) || (ip->ip_p != apr->apr_p)) return -1; KMALLOC(aps, ap_session_t *); if (!aps) return -1; bzero((char *)aps, sizeof(*aps)); aps->aps_p = ip->ip_p; aps->aps_data = NULL; aps->aps_apr = apr; aps->aps_psiz = 0; if (apr->apr_new != NULL) if ((*apr->apr_new)(fin, ip, aps, nat) == -1) { if ((aps->aps_data != NULL) && (aps->aps_psiz != 0)) { KFREES(aps->aps_data, aps->aps_psiz); } KFREE(aps); return -1; } aps->aps_nat = nat; aps->aps_next = ap_sess_list; ap_sess_list = aps; nat->nat_aps = aps; return 0; } /* * check to see if a packet should be passed through an active proxy routine * if one has been setup for it. */ int appr_check(ip, fin, nat) ip_t *ip; fr_info_t *fin; nat_t *nat; { #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6) mb_t *m = fin->fin_qfm; int dosum = 1; #endif tcphdr_t *tcp = NULL; ap_session_t *aps; aproxy_t *apr; u_32_t sum; short rv; int err; aps = nat->nat_aps; if ((aps != NULL) && (aps->aps_p == ip->ip_p)) { if (ip->ip_p == IPPROTO_TCP) { tcp = (tcphdr_t *)fin->fin_dp; /* * verify that the checksum is correct. If not, then * don't do anything with this packet. */ #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6) if (dohwcksum && (m->b_ick_flag == ICK_VALID)) { sum = tcp->th_sum; dosum = 0; } if (dosum) sum = fr_tcpsum(fin->fin_qfm, ip, tcp); #else sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip, tcp); #endif if (sum != tcp->th_sum) { #if PROXY_DEBUG printf("proxy tcp checksum failure\n"); #endif frstats[fin->fin_out].fr_tcpbad++; return -1; } /* * Don't both the proxy with these...or in fact, should * we free up proxy stuff when seen? */ if ((tcp->th_flags & TH_RST) != 0) return 0; } apr = aps->aps_apr; err = 0; if (fin->fin_out != 0) { if (apr->apr_outpkt != NULL) err = (*apr->apr_outpkt)(fin, ip, aps, nat); } else { if (apr->apr_inpkt != NULL) err = (*apr->apr_inpkt)(fin, ip, aps, nat); } rv = APR_EXIT(err); if (rv == 1) { #if PROXY_DEBUG printf("proxy says bad packet received\n"); #endif return -1; } if (rv == 2) { #if PROXY_DEBUG printf("proxy says free app proxy data\n"); #endif appr_free(apr); nat->nat_aps = NULL; return -1; } if (tcp != NULL) { err = appr_fixseqack(fin, ip, aps, APR_INC(err)); #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6) if (dosum) tcp->th_sum = fr_tcpsum(fin->fin_qfm, ip, tcp); #else tcp->th_sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip, tcp); #endif } aps->aps_bytes += ip->ip_len; aps->aps_pkts++; return 1; } return 0; } /* * Search for an proxy by the protocol it is being used with and its name. */ aproxy_t *appr_lookup(pr, name) u_int pr; char *name; { aproxy_t *ap; for (ap = ap_proxies; ap->apr_p; ap++) if ((ap->apr_p == pr) && !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) { ap->apr_ref++; return ap; } for (ap = ap_proxylist; ap; ap = ap->apr_next) if ((ap->apr_p == pr) && !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) { ap->apr_ref++; return ap; } return NULL; } void appr_free(ap) aproxy_t *ap; { ap->apr_ref--; } void aps_free(aps) ap_session_t *aps; { ap_session_t *a, **ap; aproxy_t *apr; if (!aps) return; for (ap = &ap_sess_list; (a = *ap); ap = &a->aps_next) if (a == aps) { *ap = a->aps_next; break; } apr = aps->aps_apr; if ((apr != NULL) && (apr->apr_del != NULL)) (*apr->apr_del)(aps); if ((aps->aps_data != NULL) && (aps->aps_psiz != 0)) KFREES(aps->aps_data, aps->aps_psiz); KFREE(aps); } /* * returns 2 if ack or seq number in TCP header is changed, returns 0 otherwise */ static int appr_fixseqack(fin, ip, aps, inc) fr_info_t *fin; ip_t *ip; ap_session_t *aps; int inc; { int sel, ch = 0, out, nlen; u_32_t seq1, seq2; tcphdr_t *tcp; short inc2; tcp = (tcphdr_t *)fin->fin_dp; out = fin->fin_out; /* * ip_len has already been adjusted by 'inc'. */ nlen = ip->ip_len; nlen -= (ip->ip_hl << 2) + (tcp->th_off << 2); inc2 = inc; inc = (int)inc2; if (out != 0) { seq1 = (u_32_t)ntohl(tcp->th_seq); sel = aps->aps_sel[out]; /* switch to other set ? */ if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) && (seq1 > aps->aps_seqmin[!sel])) { #if PROXY_DEBUG printf("proxy out switch set seq %d -> %d %x > %x\n", sel, !sel, seq1, aps->aps_seqmin[!sel]); #endif sel = aps->aps_sel[out] = !sel; } if (aps->aps_seqoff[sel]) { seq2 = aps->aps_seqmin[sel] - aps->aps_seqoff[sel]; if (seq1 > seq2) { seq2 = aps->aps_seqoff[sel]; seq1 += seq2; tcp->th_seq = htonl(seq1); ch = 1; } } if (inc && (seq1 > aps->aps_seqmin[!sel])) { aps->aps_seqmin[sel] = seq1 + nlen - 1; aps->aps_seqoff[sel] = aps->aps_seqoff[sel] + inc; #if PROXY_DEBUG printf("proxy seq set %d at %x to %d + %d\n", sel, aps->aps_seqmin[sel], aps->aps_seqoff[sel], inc); #endif } /***/ seq1 = ntohl(tcp->th_ack); sel = aps->aps_sel[1 - out]; /* switch to other set ? */ if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) && (seq1 > aps->aps_ackmin[!sel])) { #if PROXY_DEBUG printf("proxy out switch set ack %d -> %d %x > %x\n", sel, !sel, seq1, aps->aps_ackmin[!sel]); #endif sel = aps->aps_sel[1 - out] = !sel; } if (aps->aps_ackoff[sel] && (seq1 > aps->aps_ackmin[sel])) { seq2 = aps->aps_ackoff[sel]; tcp->th_ack = htonl(seq1 - seq2); ch = 1; } } else { seq1 = ntohl(tcp->th_seq); sel = aps->aps_sel[out]; /* switch to other set ? */ if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) && (seq1 > aps->aps_ackmin[!sel])) { #if PROXY_DEBUG printf("proxy in switch set ack %d -> %d %x > %x\n", sel, !sel, seq1, aps->aps_ackmin[!sel]); #endif sel = aps->aps_sel[out] = !sel; } if (aps->aps_ackoff[sel]) { seq2 = aps->aps_ackmin[sel] - aps->aps_ackoff[sel]; if (seq1 > seq2) { seq2 = aps->aps_ackoff[sel]; seq1 += seq2; tcp->th_seq = htonl(seq1); ch = 1; } } if (inc && (seq1 > aps->aps_ackmin[!sel])) { aps->aps_ackmin[!sel] = seq1 + nlen - 1; aps->aps_ackoff[!sel] = aps->aps_ackoff[sel] + inc; #if PROXY_DEBUG printf("proxy ack set %d at %x to %d + %d\n", !sel, aps->aps_seqmin[!sel], aps->aps_seqoff[sel], inc); #endif } /***/ seq1 = ntohl(tcp->th_ack); sel = aps->aps_sel[1 - out]; /* switch to other set ? */ if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) && (seq1 > aps->aps_seqmin[!sel])) { #if PROXY_DEBUG printf("proxy in switch set seq %d -> %d %x > %x\n", sel, !sel, seq1, aps->aps_seqmin[!sel]); #endif sel = aps->aps_sel[1 - out] = !sel; } if (aps->aps_seqoff[sel] != 0) { #if PROXY_DEBUG printf("sel %d seqoff %d seq1 %x seqmin %x\n", sel, aps->aps_seqoff[sel], seq1, aps->aps_seqmin[sel]); #endif if (seq1 > aps->aps_seqmin[sel]) { seq2 = aps->aps_seqoff[sel]; tcp->th_ack = htonl(seq1 - seq2); ch = 1; } } } #if PROXY_DEBUG printf("appr_fixseqack: seq %x ack %x\n", ntohl(tcp->th_seq), ntohl(tcp->th_ack)); #endif return ch ? 2 : 0; } /* * Initialise hook for kernel application proxies. * Call the initialise routine for all the compiled in kernel proxies. */ int appr_init() { aproxy_t *ap; int err = 0; for (ap = ap_proxies; ap->apr_p; ap++) { err = (*ap->apr_init)(); if (err != 0) break; } return err; } /* * Unload hook for kernel application proxies. * Call the finialise routine for all the compiled in kernel proxies. */ void appr_unload() { aproxy_t *ap; for (ap = ap_proxies; ap->apr_p; ap++) if (ap->apr_fini) (*ap->apr_fini)(); for (ap = ap_proxylist; ap; ap = ap->apr_next) if (ap->apr_fini) (*ap->apr_fini)(); }