/* $NetBSD: ip_rcmd_pxy.c,v 1.5 2013/09/14 12:06:19 martin Exp $ */ /* * Copyright (C) 2012 by Darren Reed. * * See the IPFILTER.LICENCE file for details on licencing. * * Id: ip_rcmd_pxy.c,v 1.1.1.2 2012/07/22 13:45:33 darrenr Exp * * Simple RCMD transparent proxy for in-kernel use. For use with the NAT * code. */ #include __KERNEL_RCSID(1, "$NetBSD: ip_rcmd_pxy.c,v 1.5 2013/09/14 12:06:19 martin Exp $"); #define IPF_RCMD_PROXY typedef struct rcmdinfo { u_32_t rcmd_port; /* Port number seen */ u_32_t rcmd_portseq; /* Sequence number where port is first seen */ ipnat_t *rcmd_rule; /* Template rule for back connection */ } rcmdinfo_t; void ipf_p_rcmd_main_load(void); void ipf_p_rcmd_main_unload(void); int ipf_p_rcmd_init(void); void ipf_p_rcmd_fini(void); void ipf_p_rcmd_del(ipf_main_softc_t *, ap_session_t *); int ipf_p_rcmd_new(void *, fr_info_t *, ap_session_t *, nat_t *); int ipf_p_rcmd_out(void *, fr_info_t *, ap_session_t *, nat_t *); int ipf_p_rcmd_in(void *, fr_info_t *, ap_session_t *, nat_t *); u_short ipf_rcmd_atoi(char *); int ipf_p_rcmd_portmsg(fr_info_t *, ap_session_t *, nat_t *); static frentry_t rcmdfr; static int rcmd_proxy_init = 0; /* * RCMD application proxy initialization. */ void ipf_p_rcmd_main_load(void) { bzero((char *)&rcmdfr, sizeof(rcmdfr)); rcmdfr.fr_ref = 1; rcmdfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE; MUTEX_INIT(&rcmdfr.fr_lock, "RCMD proxy rule lock"); rcmd_proxy_init = 1; } void ipf_p_rcmd_main_unload(void) { if (rcmd_proxy_init == 1) { MUTEX_DESTROY(&rcmdfr.fr_lock); rcmd_proxy_init = 0; } } /* * Setup for a new RCMD proxy. */ int ipf_p_rcmd_new(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat) { tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp; rcmdinfo_t *rc; ipnat_t *ipn; fin = fin; /* LINT */ KMALLOC(rc, rcmdinfo_t *); if (rc == NULL) { printf("ipf_p_rcmd_new:KMALLOCS(%zu) failed\n", sizeof(*rc)); return -1; } aps->aps_sport = tcp->th_sport; aps->aps_dport = tcp->th_dport; ipn = ipf_proxy_rule_rev(nat); if (ipn == NULL) { KFREE(rc); return -1; } aps->aps_data = rc; aps->aps_psiz = sizeof(*rc); bzero((char *)rc, sizeof(*rc)); rc->rcmd_rule = ipn; return 0; } void ipf_p_rcmd_del(ipf_main_softc_t *softc, ap_session_t *aps) { rcmdinfo_t *rci; rci = aps->aps_data; if (rci != NULL) { rci->rcmd_rule->in_flags |= IPN_DELETE; ipf_nat_rule_deref(softc, &rci->rcmd_rule); } } /* * ipf_rcmd_atoi - implement a simple version of atoi */ u_short ipf_rcmd_atoi(char *ptr) { char *s = ptr, c; u_short i = 0; while (((c = *s++) != '\0') && ISDIGIT(c)) { i *= 10; i += c - '0'; } return i; } int ipf_p_rcmd_portmsg(fr_info_t *fin, ap_session_t *aps, nat_t *nat) { tcphdr_t *tcp, tcph, *tcp2 = &tcph; int off, dlen, nflags, direction; ipf_main_softc_t *softc; ipf_nat_softc_t *softn; char portbuf[8], *s; rcmdinfo_t *rc; fr_info_t fi; u_short sp; nat_t *nat2; #ifdef USE_INET6 ip6_t *ip6; #endif int tcpsz; int slen = 0; ip_t *ip; mb_t *m; tcp = (tcphdr_t *)fin->fin_dp; m = fin->fin_m; ip = fin->fin_ip; tcpsz = TCP_OFF(tcp) << 2; #ifdef USE_INET6 ip6 = (ip6_t *)fin->fin_ip; #endif softc = fin->fin_main_soft; softn = softc->ipf_nat_soft; off = (char *)tcp - (char *)ip + tcpsz + fin->fin_ipoff; dlen = fin->fin_dlen - tcpsz; if (dlen <= 0) return 0; rc = (rcmdinfo_t *)aps->aps_data; if ((rc->rcmd_portseq != 0) && (tcp->th_seq != rc->rcmd_portseq)) return 0; bzero(portbuf, sizeof(portbuf)); COPYDATA(m, off, MIN(sizeof(portbuf), dlen), portbuf); portbuf[sizeof(portbuf) - 1] = '\0'; s = portbuf; sp = ipf_rcmd_atoi(s); if (sp == 0) { #ifdef IP_RCMD_PROXY_DEBUG printf("ipf_p_rcmd_portmsg:sp == 0 dlen %d [%s]\n", dlen, portbuf); #endif return 0; } if (rc->rcmd_port != 0 && sp != rc->rcmd_port) { #ifdef IP_RCMD_PROXY_DEBUG printf("ipf_p_rcmd_portmsg:sp(%d) != rcmd_port(%d)\n", sp, rc->rcmd_port); #endif return 0; } rc->rcmd_port = sp; rc->rcmd_portseq = tcp->th_seq; /* * Initialise the packet info structure so we can search the NAT * table to see if there already is soemthing present that matches * up with what we want to add. */ bcopy((char *)fin, (char *)&fi, sizeof(fi)); fi.fin_flx |= FI_IGNORE; fi.fin_data[0] = 0; fi.fin_data[1] = sp; fi.fin_src6 = nat->nat_ndst6; fi.fin_dst6 = nat->nat_nsrc6; if (nat->nat_v[0] == 6) { #ifdef USE_INET6 if (nat->nat_dir == NAT_OUTBOUND) { nat2 = ipf_nat6_outlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_pr[1], &nat->nat_osrc6.in6, &nat->nat_odst6.in6); } else { nat2 = ipf_nat6_inlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_pr[0], &nat->nat_osrc6.in6, &nat->nat_odst6.in6); } #else nat2 = (void *)-1; #endif } else { if (nat->nat_dir == NAT_OUTBOUND) { nat2 = ipf_nat_outlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_pr[1], nat->nat_osrcip, nat->nat_odstip); } else { nat2 = ipf_nat_inlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_pr[0], nat->nat_osrcip, nat->nat_odstip); } } if (nat2 != NULL) return APR_ERR(1); /* * Add skeleton NAT entry for connection which will come * back the other way. */ if (nat->nat_v[0] == 6) { #ifdef USE_INET6 slen = ip6->ip6_plen; ip6->ip6_plen = htons(sizeof(*tcp)); #endif } else { slen = ip->ip_len; ip->ip_len = htons(fin->fin_hlen + sizeof(*tcp)); } /* * Fill out the fake TCP header with a few fields that ipfilter * considers to be important. */ bzero((char *)tcp2, sizeof(*tcp2)); tcp2->th_win = htons(8192); TCP_OFF_A(tcp2, 5); tcp2->th_flags = TH_SYN; fi.fin_dp = (char *)tcp2; fi.fin_fr = &rcmdfr; fi.fin_dlen = sizeof(*tcp2); fi.fin_plen = fi.fin_hlen + sizeof(*tcp2); fi.fin_flx &= FI_LOWTTL|FI_FRAG|FI_TCPUDP|FI_OPTIONS|FI_IGNORE; if (nat->nat_dir == NAT_OUTBOUND) { fi.fin_out = 0; direction = NAT_INBOUND; } else { fi.fin_out = 1; direction = NAT_OUTBOUND; } nflags = SI_W_SPORT|NAT_SLAVE|IPN_TCP; MUTEX_ENTER(&softn->ipf_nat_new); if (fin->fin_v == 4) nat2 = ipf_nat_add(&fi, rc->rcmd_rule, NULL, nflags, direction); #ifdef USE_INET6 else nat2 = ipf_nat6_add(&fi, rc->rcmd_rule, NULL, nflags, direction); #endif MUTEX_EXIT(&softn->ipf_nat_new); if (nat2 != NULL) { (void) ipf_nat_proto(&fi, nat2, IPN_TCP); MUTEX_ENTER(&nat2->nat_lock); ipf_nat_update(&fi, nat2); MUTEX_EXIT(&nat2->nat_lock); fi.fin_ifp = NULL; if (nat2->nat_dir == NAT_INBOUND) fi.fin_dst6 = nat->nat_osrc6; (void) ipf_state_add(softc, &fi, NULL, SI_W_SPORT); } if (nat->nat_v[0] == 6) { #ifdef USE_INET6 ip6->ip6_plen = slen; #endif } else { ip->ip_len = slen; } if (nat2 == NULL) return APR_ERR(1); return 0; } int ipf_p_rcmd_out(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat) { if (nat->nat_dir == NAT_OUTBOUND) return ipf_p_rcmd_portmsg(fin, aps, nat); return 0; } int ipf_p_rcmd_in(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat) { if (nat->nat_dir == NAT_INBOUND) return ipf_p_rcmd_portmsg(fin, aps, nat); return 0; }