/* * Copyright (C) 1993-1997 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 !defined(lint) static const char sccsid[] = "@(#)ip_frag.c 1.11 3/24/96 (C) 1993-1995 Darren Reed"; static const char rcsid[] = "@(#)$Id: ip_frag.c,v 1.1.1.5 1997/11/16 05:55:34 peter Exp $"; #endif #if !defined(_KERNEL) && defined(KERNEL) #define _KERNEL #endif #define __FreeBSD_version 300000 /* it's a hack, but close enough */ #if !defined(_KERNEL) && !defined(KERNEL) # include # include #endif #include #include #include #include #include #if defined(KERNEL) && (__FreeBSD_version >= 220000) #include #include #include #else #include #endif #include #ifndef linux #include #endif #include #if defined(_KERNEL) && !defined(linux) # include #endif #if !defined(__SVR4) && !defined(__svr4__) # ifndef linux # include # endif #else # include # include # include # include #endif #if defined(KERNEL) && (__FreeBSD_version >= 300000) #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_proxy.h" #include "netinet/ip_nat.h" #include "netinet/ip_frag.h" #include "netinet/ip_state.h" #include "netinet/ip_auth.h" ipfr_t *ipfr_heads[IPFT_SIZE]; ipfr_t *ipfr_nattab[IPFT_SIZE]; ipfrstat_t ipfr_stats; int ipfr_inuse = 0, fr_ipfrttl = 120; /* 60 seconds */ #ifdef _KERNEL extern int ipfr_timer_id; #endif #if (SOLARIS || defined(__sgi)) && defined(_KERNEL) extern kmutex_t ipf_frag; extern kmutex_t ipf_natfrag; extern kmutex_t ipf_nat; #endif static ipfr_t *ipfr_new __P((ip_t *, fr_info_t *, int, ipfr_t **)); static ipfr_t *ipfr_lookup __P((ip_t *, fr_info_t *, ipfr_t **)); ipfrstat_t *ipfr_fragstats() { ipfr_stats.ifs_table = ipfr_heads; ipfr_stats.ifs_nattab = ipfr_nattab; ipfr_stats.ifs_inuse = ipfr_inuse; return &ipfr_stats; } /* * add a new entry to the fragment cache, registering it as having come * through this box, with the result of the filter operation. */ static ipfr_t *ipfr_new(ip, fin, pass, table) ip_t *ip; fr_info_t *fin; int pass; ipfr_t *table[]; { ipfr_t **fp, *fr, frag; u_int idx; frag.ipfr_p = ip->ip_p; idx = ip->ip_p; frag.ipfr_id = ip->ip_id; idx += ip->ip_id; frag.ipfr_tos = ip->ip_tos; frag.ipfr_src.s_addr = ip->ip_src.s_addr; idx += ip->ip_src.s_addr; frag.ipfr_dst.s_addr = ip->ip_dst.s_addr; idx += ip->ip_dst.s_addr; idx *= 127; idx %= IPFT_SIZE; /* * first, make sure it isn't already there... */ for (fp = &table[idx]; (fr = *fp); fp = &fr->ipfr_next) if (!bcmp((char *)&frag.ipfr_src, (char *)&fr->ipfr_src, IPFR_CMPSZ)) { ipfr_stats.ifs_exists++; return NULL; } /* * allocate some memory, if possible, if not, just record that we * failed to do so. */ KMALLOC(fr, ipfr_t *, sizeof(*fr)); if (fr == NULL) { ipfr_stats.ifs_nomem++; return NULL; } /* * Instert the fragment into the fragment table, copy the struct used * in the search using bcopy rather than reassign each field. * Set the ttl to the default and mask out logging from "pass" */ if ((fr->ipfr_next = table[idx])) table[idx]->ipfr_prev = fr; fr->ipfr_prev = NULL; fr->ipfr_data = NULL; table[idx] = fr; bcopy((char *)&frag.ipfr_src, (char *)&fr->ipfr_src, IPFR_CMPSZ); fr->ipfr_ttl = fr_ipfrttl; fr->ipfr_pass = pass & ~(FR_LOGFIRST|FR_LOG); /* * Compute the offset of the expected start of the next packet. */ fr->ipfr_off = (ip->ip_off & 0x1fff) + (fin->fin_dlen >> 3); ipfr_stats.ifs_new++; ipfr_inuse++; return fr; } int ipfr_newfrag(ip, fin, pass) ip_t *ip; fr_info_t *fin; int pass; { ipfr_t *ipf; MUTEX_ENTER(&ipf_frag); ipf = ipfr_new(ip, fin, pass, ipfr_heads); MUTEX_EXIT(&ipf_frag); return ipf ? 0 : -1; } int ipfr_nat_newfrag(ip, fin, pass, nat) ip_t *ip; fr_info_t *fin; int pass; nat_t *nat; { ipfr_t *ipf; MUTEX_ENTER(&ipf_natfrag); if ((ipf = ipfr_new(ip, fin, pass, ipfr_nattab))) { ipf->ipfr_data = nat; nat->nat_data = ipf; } MUTEX_EXIT(&ipf_natfrag); return ipf ? 0 : -1; } /* * check the fragment cache to see if there is already a record of this packet * with its filter result known. */ static ipfr_t *ipfr_lookup(ip, fin, table) ip_t *ip; fr_info_t *fin; ipfr_t *table[]; { ipfr_t *f, frag; u_int idx; /* * For fragments, we record protocol, packet id, TOS and both IP#'s * (these should all be the same for all fragments of a packet). * * build up a hash value to index the table with. */ frag.ipfr_p = ip->ip_p; idx = ip->ip_p; frag.ipfr_id = ip->ip_id; idx += ip->ip_id; frag.ipfr_tos = ip->ip_tos; frag.ipfr_src.s_addr = ip->ip_src.s_addr; idx += ip->ip_src.s_addr; frag.ipfr_dst.s_addr = ip->ip_dst.s_addr; idx += ip->ip_dst.s_addr; idx *= 127; idx %= IPFT_SIZE; /* * check the table, careful to only compare the right amount of data */ for (f = table[idx]; f; f = f->ipfr_next) if (!bcmp((char *)&frag.ipfr_src, (char *)&f->ipfr_src, IPFR_CMPSZ)) { u_short atoff, off; if (f != table[idx]) { /* * move fragment info. to the top of the list * to speed up searches. */ if ((f->ipfr_prev->ipfr_next = f->ipfr_next)) f->ipfr_next->ipfr_prev = f->ipfr_prev; f->ipfr_next = table[idx]; table[idx]->ipfr_prev = f; f->ipfr_prev = NULL; table[idx] = f; } off = ip->ip_off; atoff = off + (fin->fin_dlen >> 3); /* * If we've follwed the fragments, and this is the * last (in order), shrink expiration time. */ if ((off & 0x1fff) == f->ipfr_off) { if (!(off & IP_MF)) f->ipfr_ttl = 1; else f->ipfr_off = atoff; } ipfr_stats.ifs_hits++; return f; } return NULL; } /* * functional interface for NAT lookups of the NAT fragment cache */ nat_t *ipfr_nat_knownfrag(ip, fin) ip_t *ip; fr_info_t *fin; { nat_t *nat; ipfr_t *ipf; MUTEX_ENTER(&ipf_natfrag); ipf = ipfr_lookup(ip, fin, ipfr_nattab); if (ipf) { nat = ipf->ipfr_data; /* * This is the last fragment for this packet. */ if (ipf->ipfr_ttl == 1) { nat->nat_data = NULL; ipf->ipfr_data = NULL; } } else nat = NULL; MUTEX_EXIT(&ipf_natfrag); return nat; } /* * functional interface for normal lookups of the fragment cache */ int ipfr_knownfrag(ip, fin) ip_t *ip; fr_info_t *fin; { int ret; ipfr_t *ipf; MUTEX_ENTER(&ipf_frag); ipf = ipfr_lookup(ip, fin, ipfr_heads); ret = ipf ? ipf->ipfr_pass : 0; MUTEX_EXIT(&ipf_frag); return ret; } /* * forget any references to this external object. */ void ipfr_forget(nat) void *nat; { ipfr_t *fr; int idx; MUTEX_ENTER(&ipf_natfrag); for (idx = IPFT_SIZE - 1; idx >= 0; idx--) for (fr = ipfr_heads[idx]; fr; fr = fr->ipfr_next) if (fr->ipfr_data == nat) fr->ipfr_data = NULL; MUTEX_EXIT(&ipf_natfrag); } /* * Free memory in use by fragment state info. kept. */ void ipfr_unload() { ipfr_t **fp, *fr; nat_t *nat; int idx; MUTEX_ENTER(&ipf_frag); for (idx = IPFT_SIZE - 1; idx >= 0; idx--) for (fp = &ipfr_heads[idx]; (fr = *fp); ) { *fp = fr->ipfr_next; KFREE(fr); } MUTEX_EXIT(&ipf_frag); MUTEX_ENTER(&ipf_nat); MUTEX_ENTER(&ipf_natfrag); for (idx = IPFT_SIZE - 1; idx >= 0; idx--) for (fp = &ipfr_nattab[idx]; (fr = *fp); ) { *fp = fr->ipfr_next; if ((nat = (nat_t *)fr->ipfr_data)) { if (nat->nat_data == fr) nat->nat_data = NULL; } KFREE(fr); } MUTEX_EXIT(&ipf_natfrag); MUTEX_EXIT(&ipf_nat); } #ifdef _KERNEL /* * Slowly expire held state for fragments. Timeouts are set * in expectation * of this being called twice per second. */ # if (BSD >= 199306) || SOLARIS || defined(__sgi) void ipfr_slowtimer() # else int ipfr_slowtimer() # endif { ipfr_t **fp, *fr; nat_t *nat; int s, idx; #ifdef __sgi ipfilter_sgi_intfsync(); #endif SPL_NET(s); MUTEX_ENTER(&ipf_frag); /* * Go through the entire table, looking for entries to expire, * decreasing the ttl by one for each entry. If it reaches 0, * remove it from the chain and free it. */ for (idx = IPFT_SIZE - 1; idx >= 0; idx--) for (fp = &ipfr_heads[idx]; (fr = *fp); ) { --fr->ipfr_ttl; if (fr->ipfr_ttl == 0) { if (fr->ipfr_prev) fr->ipfr_prev->ipfr_next = fr->ipfr_next; if (fr->ipfr_next) fr->ipfr_next->ipfr_prev = fr->ipfr_prev; *fp = fr->ipfr_next; ipfr_stats.ifs_expire++; ipfr_inuse--; KFREE(fr); } else fp = &fr->ipfr_next; } MUTEX_EXIT(&ipf_frag); /* * Same again for the NAT table, except that if the structure also * still points to a NAT structure, and the NAT structure points back * at the one to be free'd, NULL the reference from the NAT struct. * NOTE: We need to grab both mutex's early, and in this order so as * to prevent a deadlock if both try to expire at the same time. */ MUTEX_ENTER(&ipf_nat); MUTEX_ENTER(&ipf_natfrag); for (idx = IPFT_SIZE - 1; idx >= 0; idx--) for (fp = &ipfr_nattab[idx]; (fr = *fp); ) { --fr->ipfr_ttl; if (fr->ipfr_ttl == 0) { if (fr->ipfr_prev) fr->ipfr_prev->ipfr_next = fr->ipfr_next; if (fr->ipfr_next) fr->ipfr_next->ipfr_prev = fr->ipfr_prev; *fp = fr->ipfr_next; ipfr_stats.ifs_expire++; ipfr_inuse--; if ((nat = (nat_t *)fr->ipfr_data)) { if (nat->nat_data == fr) nat->nat_data = NULL; } KFREE(fr); } else fp = &fr->ipfr_next; } MUTEX_EXIT(&ipf_natfrag); MUTEX_EXIT(&ipf_nat); SPL_X(s); fr_timeoutstate(); ip_natexpire(); fr_authexpire(); # if SOLARIS ipfr_timer_id = timeout(ipfr_slowtimer, NULL, drv_usectohz(500000)); # else # ifndef linux ip_slowtimo(); # endif # if (BSD < 199306) && !defined(__sgi) return 0; # endif # endif } #endif /* defined(_KERNEL) */