/* $OpenBSD: gencode.c,v 1.9 1998/07/14 00:14:00 deraadt Exp $ */ /* * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that: (1) source code distributions * retain the above copyright notice and this paragraph in its entirety, (2) * distributions including binary code include the above copyright notice and * this paragraph in its entirety in the documentation or other materials * provided with the distribution, and (3) all advertising materials mentioning * features or use of this software display the following acknowledgement: * ``This product includes software developed by the University of California, * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of * the University nor the names of its contributors may 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 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ #ifndef lint static char rcsid[] = "@(#) Header: gencode.c,v 1.81 96/06/19 23:09:09 leres Exp (LBL)"; #endif #include #include #include #ifdef __STDC__ struct mbuf; struct rtentry; #endif #include #include #include #include #include #include #include #include #include #ifdef __STDC__ #include #else #include #endif #ifdef HAVE_OS_PROTO_H #include "os-proto.h" #endif #include "pcap-int.h" #include "gencode.h" #ifndef ETHERTYPE_REVARP #define ETHERTYPE_REVARP 0x8035 #endif #ifndef ETHERTYPE_MOPDL #define ETHERTYPE_MOPDL 0x6001 #endif #ifndef ETHERTYPE_MOPRC #define ETHERTYPE_MOPRC 0x6002 #endif #ifndef ETHERTYPE_DN #define ETHERTYPE_DN 0x6003 #endif #ifndef ETHERTYPE_LAT #define ETHERTYPE_LAT 0x6004 #endif #define JMP(c) ((c)|BPF_JMP|BPF_K) /* Locals */ static jmp_buf top_ctx; static pcap_t *bpf_pcap; /* XXX */ #ifdef PCAP_FDDIPAD int pcap_fddipad = PCAP_FDDIPAD; #else int pcap_fddipad; #endif /* VARARGS */ __dead void #ifdef __STDC__ bpf_error(const char *fmt, ...) #else bpf_error(fmt, va_alist) const char *fmt; va_dcl #endif { va_list ap; #ifdef __STDC__ va_start(ap, fmt); #else va_start(ap); #endif if (bpf_pcap != NULL) (void)vsnprintf(pcap_geterr(bpf_pcap), PCAP_ERRBUF_SIZE, fmt, ap); va_end(ap); longjmp(top_ctx, 1); /* NOTREACHED */ } static void init_linktype(int); static int alloc_reg(void); static void free_reg(int); static struct block *root; /* * We divy out chunks of memory rather than call malloc each time so * we don't have to worry about leaking memory. It's probably * not a big deal if all this memory was wasted but it this ever * goes into a library that would probably not be a good idea. */ #define NCHUNKS 16 #define CHUNK0SIZE 1024 struct chunk { u_int n_left; void *m; }; static struct chunk chunks[NCHUNKS]; static int cur_chunk; static void *newchunk(u_int); static void freechunks(void); static __inline struct block *new_block(int); static __inline struct slist *new_stmt(int); static struct block *gen_retblk(int); static __inline void syntax(void); static void backpatch(struct block *, struct block *); static void merge(struct block *, struct block *); static struct block *gen_cmp(u_int, u_int, bpf_int32); static struct block *gen_mcmp(u_int, u_int, bpf_int32, bpf_u_int32); static struct block *gen_bcmp(u_int, u_int, u_char *); static struct block *gen_uncond(int); static __inline struct block *gen_true(void); static __inline struct block *gen_false(void); static struct block *gen_linktype(int); static struct block *gen_hostop(bpf_u_int32, bpf_u_int32, int, int, u_int, u_int); static struct block *gen_ehostop(u_char *, int); static struct block *gen_fhostop(u_char *, int); static struct block *gen_dnhostop(bpf_u_int32, int, u_int); static struct block *gen_host(bpf_u_int32, bpf_u_int32, int, int); static struct block *gen_gateway(u_char *, bpf_u_int32 **, int, int); static struct block *gen_ipfrag(void); static struct block *gen_portatom(int, bpf_int32); struct block *gen_portop(int, int, int); static struct block *gen_port(int, int, int); static int lookup_proto(char *, int); static struct block *gen_proto(int, int, int); static bpf_u_int32 net_mask(bpf_u_int32 *); static struct slist *xfer_to_x(struct arth *); static struct slist *xfer_to_a(struct arth *); static struct block *gen_len(int, int); static void * newchunk(n) u_int n; { struct chunk *cp; int k, size; /* XXX Round up to nearest long. */ n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1); cp = &chunks[cur_chunk]; if (n > cp->n_left) { ++cp, k = ++cur_chunk; if (k >= NCHUNKS) bpf_error("out of memory"); size = CHUNK0SIZE << k; cp->m = (void *)malloc(size); memset((char *)cp->m, 0, size); cp->n_left = size; if (n > size) bpf_error("out of memory"); } cp->n_left -= n; return (void *)((char *)cp->m + cp->n_left); } static void freechunks() { int i; cur_chunk = 0; for (i = 0; i < NCHUNKS; ++i) if (chunks[i].m != NULL) { free(chunks[i].m); chunks[i].m = NULL; } } /* * A strdup whose allocations are freed after code generation is over. */ char * sdup(s) char *s; { int n = strlen(s) + 1; char *cp = newchunk(n); strcpy(cp, s); return (cp); } static __inline struct block * new_block(code) int code; { struct block *p; p = (struct block *)newchunk(sizeof(*p)); p->s.code = code; p->head = p; return p; } static __inline struct slist * new_stmt(code) int code; { struct slist *p; p = (struct slist *)newchunk(sizeof(*p)); p->s.code = code; return p; } static struct block * gen_retblk(v) int v; { struct block *b = new_block(BPF_RET|BPF_K); b->s.k = v; return b; } static __inline void syntax() { bpf_error("syntax error in filter expression"); } static bpf_u_int32 netmask; static int snaplen; int pcap_compile(pcap_t *p, struct bpf_program *program, char *buf, int optimize, bpf_u_int32 mask) { extern int n_errors; int len; n_errors = 0; root = NULL; bpf_pcap = p; if (setjmp(top_ctx)) { freechunks(); return (-1); } netmask = mask; snaplen = pcap_snapshot(p); lex_init(buf ? buf : ""); init_linktype(pcap_datalink(p)); (void)pcap_parse(); if (n_errors) syntax(); if (root == NULL) root = gen_retblk(snaplen); if (optimize) { bpf_optimize(&root); if (root == NULL || (root->s.code == (BPF_RET|BPF_K) && root->s.k == 0)) bpf_error("expression rejects all packets"); } program->bf_insns = icode_to_fcode(root, &len); program->bf_len = len; freechunks(); return (0); } /* * Backpatch the blocks in 'list' to 'target'. The 'sense' field indicates * which of the jt and jf fields has been resolved and which is a pointer * back to another unresolved block (or nil). At least one of the fields * in each block is already resolved. */ static void backpatch(list, target) struct block *list, *target; { struct block *next; while (list) { if (!list->sense) { next = JT(list); JT(list) = target; } else { next = JF(list); JF(list) = target; } list = next; } } /* * Merge the lists in b0 and b1, using the 'sense' field to indicate * which of jt and jf is the link. */ static void merge(b0, b1) struct block *b0, *b1; { register struct block **p = &b0; /* Find end of list. */ while (*p) p = !((*p)->sense) ? &JT(*p) : &JF(*p); /* Concatenate the lists. */ *p = b1; } void finish_parse(p) struct block *p; { backpatch(p, gen_retblk(snaplen)); p->sense = !p->sense; backpatch(p, gen_retblk(0)); root = p->head; } void gen_and(b0, b1) struct block *b0, *b1; { backpatch(b0, b1->head); b0->sense = !b0->sense; b1->sense = !b1->sense; merge(b1, b0); b1->sense = !b1->sense; b1->head = b0->head; } void gen_or(b0, b1) struct block *b0, *b1; { b0->sense = !b0->sense; backpatch(b0, b1->head); b0->sense = !b0->sense; merge(b1, b0); b1->head = b0->head; } void gen_not(b) struct block *b; { b->sense = !b->sense; } static struct block * gen_cmp(offset, size, v) u_int offset, size; bpf_int32 v; { struct slist *s; struct block *b; s = new_stmt(BPF_LD|BPF_ABS|size); s->s.k = offset; b = new_block(JMP(BPF_JEQ)); b->stmts = s; b->s.k = v; return b; } static struct block * gen_mcmp(offset, size, v, mask) u_int offset, size; bpf_int32 v; bpf_u_int32 mask; { struct block *b = gen_cmp(offset, size, v); struct slist *s; if (mask != 0xffffffff) { s = new_stmt(BPF_ALU|BPF_AND|BPF_K); s->s.k = mask; b->stmts->next = s; } return b; } static struct block * gen_bcmp(offset, size, v) u_int offset, size; u_char *v; { struct block *b, *tmp; b = NULL; while (size >= 4) { u_char *p = &v[size - 4]; bpf_int32 w = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]; tmp = gen_cmp(offset + size - 4, BPF_W, w); if (b != NULL) gen_and(b, tmp); b = tmp; size -= 4; } while (size >= 2) { u_char *p = &v[size - 2]; bpf_int32 w = (p[0] << 8) | p[1]; tmp = gen_cmp(offset + size - 2, BPF_H, w); if (b != NULL) gen_and(b, tmp); b = tmp; size -= 2; } if (size > 0) { tmp = gen_cmp(offset, BPF_B, (bpf_int32)v[0]); if (b != NULL) gen_and(b, tmp); b = tmp; } return b; } /* * Various code constructs need to know the layout of the data link * layer. These variables give the necessary offsets. off_linktype * is set to -1 for no encapsulation, in which case, IP is assumed. */ static u_int off_linktype; static u_int off_nl; static int linktype; static void init_linktype(type) int type; { linktype = type; switch (type) { case DLT_EN10MB: off_linktype = 12; off_nl = 14; return; case DLT_SLIP: /* * SLIP doesn't have a link level type. The 16 byte * header is hacked into our SLIP driver. */ off_linktype = -1; off_nl = 16; return; case DLT_NULL: off_linktype = -1; off_nl = 0; return; case DLT_LOOP: off_linktype = -1; off_nl = 4; return; case DLT_ENC: off_linktype = -1; off_nl = 12; return; case DLT_PPP: off_linktype = 2; off_nl = 4; return; case DLT_FDDI: /* * FDDI doesn't really have a link-level type field. * We assume that SSAP = SNAP is being used and pick * out the encapsulated Ethernet type. */ off_linktype = 19; #ifdef PCAP_FDDIPAD off_linktype += pcap_fddipad; #endif off_nl = 21; #ifdef PCAP_FDDIPAD off_nl += pcap_fddipad; #endif return; case DLT_IEEE802: off_linktype = 20; off_nl = 22; return; case DLT_ATM_RFC1483: /* * assume routed, non-ISO PDUs * (i.e., LLC = 0xAA-AA-03, OUT = 0x00-00-00) */ off_linktype = 6; off_nl = 8; return; } bpf_error("unknown data link type 0x%x", linktype); /* NOTREACHED */ } static struct block * gen_uncond(rsense) int rsense; { struct block *b; struct slist *s; s = new_stmt(BPF_LD|BPF_IMM); s->s.k = !rsense; b = new_block(JMP(BPF_JEQ)); b->stmts = s; return b; } static __inline struct block * gen_true() { return gen_uncond(1); } static __inline struct block * gen_false() { return gen_uncond(0); } static struct block * gen_linktype(proto) int proto; { switch (linktype) { case DLT_SLIP: if (proto == ETHERTYPE_IP) return gen_true(); else return gen_false(); case DLT_PPP: if (proto == ETHERTYPE_IP) proto = 0x0021; /* XXX - need ppp.h defs */ break; case DLT_ENC: case DLT_LOOP: case DLT_NULL: /* XXX */ if (proto == ETHERTYPE_IP) return (gen_cmp(0, BPF_W, htonl((bpf_int32) AF_INET))); else return gen_false(); } return gen_cmp(off_linktype, BPF_H, (bpf_int32)proto); } static struct block * gen_hostop(addr, mask, dir, proto, src_off, dst_off) bpf_u_int32 addr; bpf_u_int32 mask; int dir, proto; u_int src_off, dst_off; { struct block *b0, *b1; u_int offset; switch (dir) { case Q_SRC: offset = src_off; break; case Q_DST: offset = dst_off; break; case Q_AND: b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off); b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off); gen_and(b0, b1); return b1; case Q_OR: case Q_DEFAULT: b0 = gen_hostop(addr, mask, Q_SRC, proto, src_off, dst_off); b1 = gen_hostop(addr, mask, Q_DST, proto, src_off, dst_off); gen_or(b0, b1); return b1; default: abort(); } b0 = gen_linktype(proto); b1 = gen_mcmp(offset, BPF_W, (bpf_int32)addr, mask); gen_and(b0, b1); return b1; } static struct block * gen_ehostop(eaddr, dir) u_char *eaddr; int dir; { struct block *b0, *b1; switch (dir) { case Q_SRC: return gen_bcmp(6, 6, eaddr); case Q_DST: return gen_bcmp(0, 6, eaddr); case Q_AND: b0 = gen_ehostop(eaddr, Q_SRC); b1 = gen_ehostop(eaddr, Q_DST); gen_and(b0, b1); return b1; case Q_DEFAULT: case Q_OR: b0 = gen_ehostop(eaddr, Q_SRC); b1 = gen_ehostop(eaddr, Q_DST); gen_or(b0, b1); return b1; } abort(); /* NOTREACHED */ } /* * Like gen_ehostop, but for DLT_FDDI */ static struct block * gen_fhostop(eaddr, dir) u_char *eaddr; int dir; { struct block *b0, *b1; switch (dir) { case Q_SRC: #ifdef PCAP_FDDIPAD return gen_bcmp(6 + 1 + pcap_fddipad, 6, eaddr); #else return gen_bcmp(6 + 1, 6, eaddr); #endif case Q_DST: #ifdef PCAP_FDDIPAD return gen_bcmp(0 + 1 + pcap_fddipad, 6, eaddr); #else return gen_bcmp(0 + 1, 6, eaddr); #endif case Q_AND: b0 = gen_fhostop(eaddr, Q_SRC); b1 = gen_fhostop(eaddr, Q_DST); gen_and(b0, b1); return b1; case Q_DEFAULT: case Q_OR: b0 = gen_fhostop(eaddr, Q_SRC); b1 = gen_fhostop(eaddr, Q_DST); gen_or(b0, b1); return b1; } abort(); /* NOTREACHED */ } /* * This is quite tricky because there may be pad bytes in front of the * DECNET header, and then there are two possible data packet formats that * carry both src and dst addresses, plus 5 packet types in a format that * carries only the src node, plus 2 types that use a different format and * also carry just the src node. * * Yuck. * * Instead of doing those all right, we just look for data packets with * 0 or 1 bytes of padding. If you want to look at other packets, that * will require a lot more hacking. * * To add support for filtering on DECNET "areas" (network numbers) * one would want to add a "mask" argument to this routine. That would * make the filter even more inefficient, although one could be clever * and not generate masking instructions if the mask is 0xFFFF. */ static struct block * gen_dnhostop(addr, dir, base_off) bpf_u_int32 addr; int dir; u_int base_off; { struct block *b0, *b1, *b2, *tmp; u_int offset_lh; /* offset if long header is received */ u_int offset_sh; /* offset if short header is received */ switch (dir) { case Q_DST: offset_sh = 1; /* follows flags */ offset_lh = 7; /* flgs,darea,dsubarea,HIORD */ break; case Q_SRC: offset_sh = 3; /* follows flags, dstnode */ offset_lh = 15; /* flgs,darea,dsubarea,did,sarea,ssub,HIORD */ break; case Q_AND: /* Inefficient because we do our Calvinball dance twice */ b0 = gen_dnhostop(addr, Q_SRC, base_off); b1 = gen_dnhostop(addr, Q_DST, base_off); gen_and(b0, b1); return b1; case Q_OR: case Q_DEFAULT: /* Inefficient because we do our Calvinball dance twice */ b0 = gen_dnhostop(addr, Q_SRC, base_off); b1 = gen_dnhostop(addr, Q_DST, base_off); gen_or(b0, b1); return b1; default: abort(); } b0 = gen_linktype(ETHERTYPE_DN); /* Check for pad = 1, long header case */ tmp = gen_mcmp(base_off + 2, BPF_H, (bpf_int32)ntohs(0x0681), (bpf_int32)ntohs(0x07FF)); b1 = gen_cmp(base_off + 2 + 1 + offset_lh, BPF_H, (bpf_int32)ntohs(addr)); gen_and(tmp, b1); /* Check for pad = 0, long header case */ tmp = gen_mcmp(base_off + 2, BPF_B, (bpf_int32)0x06, (bpf_int32)0x7); b2 = gen_cmp(base_off + 2 + offset_lh, BPF_H, (bpf_int32)ntohs(addr)); gen_and(tmp, b2); gen_or(b2, b1); /* Check for pad = 1, short header case */ tmp = gen_mcmp(base_off + 2, BPF_H, (bpf_int32)ntohs(0x0281), (bpf_int32)ntohs(0x07FF)); b2 = gen_cmp(base_off + 2 + 1 + offset_sh, BPF_H, (bpf_int32)ntohs(addr)); gen_and(tmp, b2); gen_or(b2, b1); /* Check for pad = 0, short header case */ tmp = gen_mcmp(base_off + 2, BPF_B, (bpf_int32)0x02, (bpf_int32)0x7); b2 = gen_cmp(base_off + 2 + offset_sh, BPF_H, (bpf_int32)ntohs(addr)); gen_and(tmp, b2); gen_or(b2, b1); /* Combine with test for linktype */ gen_and(b0, b1); return b1; } static struct block * gen_host(addr, mask, proto, dir) bpf_u_int32 addr; bpf_u_int32 mask; int proto; int dir; { struct block *b0, *b1; switch (proto) { case Q_DEFAULT: b0 = gen_host(addr, mask, Q_IP, dir); b1 = gen_host(addr, mask, Q_ARP, dir); gen_or(b0, b1); b0 = gen_host(addr, mask, Q_RARP, dir); gen_or(b1, b0); return b0; case Q_IP: return gen_hostop(addr, mask, dir, ETHERTYPE_IP, off_nl + 12, off_nl + 16); case Q_RARP: return gen_hostop(addr, mask, dir, ETHERTYPE_REVARP, off_nl + 14, off_nl + 24); case Q_ARP: return gen_hostop(addr, mask, dir, ETHERTYPE_ARP, off_nl + 14, off_nl + 24); case Q_TCP: bpf_error("'tcp' modifier applied to host"); case Q_UDP: bpf_error("'udp' modifier applied to host"); case Q_ICMP: bpf_error("'icmp' modifier applied to host"); case Q_IGMP: bpf_error("'igmp' modifier applied to host"); case Q_DECNET: return gen_dnhostop(addr, dir, off_nl); case Q_LAT: bpf_error("LAT host filtering not implemented"); case Q_MOPDL: bpf_error("MOPDL host filtering not implemented"); case Q_MOPRC: bpf_error("MOPRC host filtering not implemented"); default: abort(); } /* NOTREACHED */ } static struct block * gen_gateway(eaddr, alist, proto, dir) u_char *eaddr; bpf_u_int32 **alist; int proto; int dir; { struct block *b0, *b1, *tmp; if (dir != 0) bpf_error("direction applied to 'gateway'"); switch (proto) { case Q_DEFAULT: case Q_IP: case Q_ARP: case Q_RARP: if (linktype == DLT_EN10MB) b0 = gen_ehostop(eaddr, Q_OR); else if (linktype == DLT_FDDI) b0 = gen_fhostop(eaddr, Q_OR); else bpf_error( "'gateway' supported only on ethernet or FDDI"); b1 = gen_host(**alist++, 0xffffffffL, proto, Q_OR); while (*alist) { tmp = gen_host(**alist++, 0xffffffffL, proto, Q_OR); gen_or(b1, tmp); b1 = tmp; } gen_not(b1); gen_and(b0, b1); return b1; } bpf_error("illegal modifier of 'gateway'"); /* NOTREACHED */ } struct block * gen_proto_abbrev(proto) int proto; { struct block *b0, *b1; switch (proto) { case Q_TCP: b0 = gen_linktype(ETHERTYPE_IP); b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_TCP); gen_and(b0, b1); break; case Q_UDP: b0 = gen_linktype(ETHERTYPE_IP); b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_UDP); gen_and(b0, b1); break; case Q_ICMP: b0 = gen_linktype(ETHERTYPE_IP); b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)IPPROTO_ICMP); gen_and(b0, b1); break; case Q_IGMP: b0 = gen_linktype(ETHERTYPE_IP); b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)2); gen_and(b0, b1); break; case Q_IP: b1 = gen_linktype(ETHERTYPE_IP); break; case Q_ARP: b1 = gen_linktype(ETHERTYPE_ARP); break; case Q_RARP: b1 = gen_linktype(ETHERTYPE_REVARP); break; case Q_LINK: bpf_error("link layer applied in wrong context"); case Q_DECNET: b1 = gen_linktype(ETHERTYPE_DN); break; case Q_LAT: b1 = gen_linktype(ETHERTYPE_LAT); break; case Q_MOPDL: b1 = gen_linktype(ETHERTYPE_MOPDL); break; case Q_MOPRC: b1 = gen_linktype(ETHERTYPE_MOPRC); break; default: abort(); } return b1; } static struct block * gen_ipfrag() { struct slist *s; struct block *b; /* not ip frag */ s = new_stmt(BPF_LD|BPF_H|BPF_ABS); s->s.k = off_nl + 6; b = new_block(JMP(BPF_JSET)); b->s.k = 0x1fff; b->stmts = s; gen_not(b); return b; } static struct block * gen_portatom(off, v) int off; bpf_int32 v; { struct slist *s; struct block *b; s = new_stmt(BPF_LDX|BPF_MSH|BPF_B); s->s.k = off_nl; s->next = new_stmt(BPF_LD|BPF_IND|BPF_H); s->next->s.k = off_nl + off; b = new_block(JMP(BPF_JEQ)); b->stmts = s; b->s.k = v; return b; } struct block * gen_portop(port, proto, dir) int port, proto, dir; { struct block *b0, *b1, *tmp; /* ip proto 'proto' */ tmp = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)proto); b0 = gen_ipfrag(); gen_and(tmp, b0); switch (dir) { case Q_SRC: b1 = gen_portatom(0, (bpf_int32)port); break; case Q_DST: b1 = gen_portatom(2, (bpf_int32)port); break; case Q_OR: case Q_DEFAULT: tmp = gen_portatom(0, (bpf_int32)port); b1 = gen_portatom(2, (bpf_int32)port); gen_or(tmp, b1); break; case Q_AND: tmp = gen_portatom(0, (bpf_int32)port); b1 = gen_portatom(2, (bpf_int32)port); gen_and(tmp, b1); break; default: abort(); } gen_and(b0, b1); return b1; } static struct block * gen_port(port, ip_proto, dir) int port; int ip_proto; int dir; { struct block *b0, *b1, *tmp; /* ether proto ip */ b0 = gen_linktype(ETHERTYPE_IP); switch (ip_proto) { case IPPROTO_UDP: case IPPROTO_TCP: b1 = gen_portop(port, ip_proto, dir); break; case PROTO_UNDEF: tmp = gen_portop(port, IPPROTO_TCP, dir); b1 = gen_portop(port, IPPROTO_UDP, dir); gen_or(tmp, b1); break; default: abort(); } gen_and(b0, b1); return b1; } static int lookup_proto(name, proto) char *name; int proto; { int v; switch (proto) { case Q_DEFAULT: case Q_IP: v = pcap_nametoproto(name); if (v == PROTO_UNDEF) bpf_error("unknown ip proto '%s'", name); break; case Q_LINK: /* XXX should look up h/w protocol type based on linktype */ v = pcap_nametoeproto(name); if (v == PROTO_UNDEF) bpf_error("unknown ether proto '%s'", name); break; default: v = PROTO_UNDEF; break; } return v; } static struct block * gen_proto(v, proto, dir) int v; int proto; int dir; { struct block *b0, *b1; if (dir != Q_DEFAULT) bpf_error("direction applied to 'proto'"); switch (proto) { case Q_DEFAULT: case Q_IP: b0 = gen_linktype(ETHERTYPE_IP); b1 = gen_cmp(off_nl + 9, BPF_B, (bpf_int32)v); gen_and(b0, b1); return b1; case Q_ARP: bpf_error("arp does not encapsulate another protocol"); /* NOTREACHED */ case Q_RARP: bpf_error("rarp does not encapsulate another protocol"); /* NOTREACHED */ case Q_DECNET: bpf_error("decnet encapsulation is not specifiable"); /* NOTREACHED */ case Q_LAT: bpf_error("lat does not encapsulate another protocol"); /* NOTREACHED */ case Q_MOPRC: bpf_error("moprc does not encapsulate another protocol"); /* NOTREACHED */ case Q_MOPDL: bpf_error("mopdl does not encapsulate another protocol"); /* NOTREACHED */ case Q_LINK: return gen_linktype(v); case Q_UDP: bpf_error("'udp proto' is bogus"); /* NOTREACHED */ case Q_TCP: bpf_error("'tcp proto' is bogus"); /* NOTREACHED */ case Q_ICMP: bpf_error("'icmp proto' is bogus"); /* NOTREACHED */ case Q_IGMP: bpf_error("'igmp proto' is bogus"); /* NOTREACHED */ default: abort(); /* NOTREACHED */ } /* NOTREACHED */ } /* * Left justify 'addr' and return its resulting network mask. */ static bpf_u_int32 net_mask(addr) bpf_u_int32 *addr; { register bpf_u_int32 m = 0xffffffff; if (*addr) while ((*addr & 0xff000000) == 0) *addr <<= 8, m <<= 8; return m; } struct block * gen_scode(name, q) char *name; struct qual q; { int proto = q.proto; int dir = q.dir; u_char *eaddr; bpf_u_int32 mask, addr, **alist; struct block *b, *tmp; int port, real_proto; switch (q.addr) { case Q_NET: addr = pcap_nametonetaddr(name); if (addr == 0) bpf_error("unknown network '%s'", name); mask = net_mask(&addr); return gen_host(addr, mask, proto, dir); case Q_DEFAULT: case Q_HOST: if (proto == Q_LINK) { switch (linktype) { case DLT_EN10MB: eaddr = pcap_ether_hostton(name); if (eaddr == NULL) bpf_error( "unknown ether host '%s'", name); return gen_ehostop(eaddr, dir); case DLT_FDDI: eaddr = pcap_ether_hostton(name); if (eaddr == NULL) bpf_error( "unknown FDDI host '%s'", name); return gen_fhostop(eaddr, dir); default: bpf_error( "only ethernet/FDDI supports link-level host name"); break; } } else if (proto == Q_DECNET) { unsigned short dn_addr = __pcap_nametodnaddr(name); /* * I don't think DECNET hosts can be multihomed, so * there is no need to build up a list of addresses */ return (gen_host(dn_addr, 0, proto, dir)); } else { alist = pcap_nametoaddr(name); if (alist == NULL || *alist == NULL) bpf_error("unknown host '%s'", name); b = gen_host(**alist++, 0xffffffffL, proto, dir); while (*alist) { tmp = gen_host(**alist++, 0xffffffffL, proto, dir); gen_or(b, tmp); b = tmp; } return b; } case Q_PORT: if (proto != Q_DEFAULT && proto != Q_UDP && proto != Q_TCP) bpf_error("illegal qualifier of 'port'"); if (pcap_nametoport(name, &port, &real_proto) == 0) bpf_error("unknown port '%s'", name); if (proto == Q_UDP) { if (real_proto == IPPROTO_TCP) bpf_error("port '%s' is tcp", name); else /* override PROTO_UNDEF */ real_proto = IPPROTO_UDP; } if (proto == Q_TCP) { if (real_proto == IPPROTO_UDP) bpf_error("port '%s' is udp", name); else /* override PROTO_UNDEF */ real_proto = IPPROTO_TCP; } return gen_port(port, real_proto, dir); case Q_GATEWAY: eaddr = pcap_ether_hostton(name); if (eaddr == NULL) bpf_error("unknown ether host: %s", name); alist = pcap_nametoaddr(name); if (alist == NULL || *alist == NULL) bpf_error("unknown host '%s'", name); return gen_gateway(eaddr, alist, proto, dir); case Q_PROTO: real_proto = lookup_proto(name, proto); if (real_proto >= 0) return gen_proto(real_proto, proto, dir); else bpf_error("unknown protocol: %s", name); case Q_UNDEF: syntax(); /* NOTREACHED */ } abort(); /* NOTREACHED */ } struct block * gen_ncode(v, q) bpf_u_int32 v; struct qual q; { bpf_u_int32 mask; int proto = q.proto; int dir = q.dir; switch (q.addr) { case Q_DEFAULT: case Q_HOST: case Q_NET: if (proto == Q_DECNET) return gen_host(v, 0, proto, dir); else if (proto == Q_LINK) { bpf_error("illegal link layer address"); } else { mask = net_mask(&v); return gen_host(v, mask, proto, dir); } case Q_PORT: if (proto == Q_UDP) proto = IPPROTO_UDP; else if (proto == Q_TCP) proto = IPPROTO_TCP; else if (proto == Q_DEFAULT) proto = PROTO_UNDEF; else bpf_error("illegal qualifier of 'port'"); return gen_port((int)v, proto, dir); case Q_GATEWAY: bpf_error("'gateway' requires a name"); /* NOTREACHED */ case Q_PROTO: return gen_proto((int)v, proto, dir); case Q_UNDEF: syntax(); /* NOTREACHED */ default: abort(); /* NOTREACHED */ } /* NOTREACHED */ } struct block * gen_ecode(eaddr, q) u_char *eaddr; struct qual q; { if ((q.addr == Q_HOST || q.addr == Q_DEFAULT) && q.proto == Q_LINK) { if (linktype == DLT_EN10MB) return gen_ehostop(eaddr, (int)q.dir); if (linktype == DLT_FDDI) return gen_fhostop(eaddr, (int)q.dir); } bpf_error("ethernet address used in non-ether expression"); /* NOTREACHED */ } void sappend(s0, s1) struct slist *s0, *s1; { /* * This is definitely not the best way to do this, but the * lists will rarely get long. */ while (s0->next) s0 = s0->next; s0->next = s1; } static struct slist * xfer_to_x(a) struct arth *a; { struct slist *s; s = new_stmt(BPF_LDX|BPF_MEM); s->s.k = a->regno; return s; } static struct slist * xfer_to_a(a) struct arth *a; { struct slist *s; s = new_stmt(BPF_LD|BPF_MEM); s->s.k = a->regno; return s; } struct arth * gen_load(proto, index, size) int proto; struct arth *index; int size; { struct slist *s, *tmp; struct block *b; int regno = alloc_reg(); free_reg(index->regno); switch (size) { default: bpf_error("data size must be 1, 2, or 4"); case 1: size = BPF_B; break; case 2: size = BPF_H; break; case 4: size = BPF_W; break; } switch (proto) { default: bpf_error("unsupported index operation"); case Q_LINK: s = xfer_to_x(index); tmp = new_stmt(BPF_LD|BPF_IND|size); sappend(s, tmp); sappend(index->s, s); break; case Q_IP: case Q_ARP: case Q_RARP: case Q_DECNET: case Q_LAT: case Q_MOPRC: case Q_MOPDL: /* XXX Note that we assume a fixed link link header here. */ s = xfer_to_x(index); tmp = new_stmt(BPF_LD|BPF_IND|size); tmp->s.k = off_nl; sappend(s, tmp); sappend(index->s, s); b = gen_proto_abbrev(proto); if (index->b) gen_and(index->b, b); index->b = b; break; case Q_TCP: case Q_UDP: case Q_ICMP: case Q_IGMP: s = new_stmt(BPF_LDX|BPF_MSH|BPF_B); s->s.k = off_nl; sappend(s, xfer_to_a(index)); sappend(s, new_stmt(BPF_ALU|BPF_ADD|BPF_X)); sappend(s, new_stmt(BPF_MISC|BPF_TAX)); sappend(s, tmp = new_stmt(BPF_LD|BPF_IND|size)); tmp->s.k = off_nl; sappend(index->s, s); gen_and(gen_proto_abbrev(proto), b = gen_ipfrag()); if (index->b) gen_and(index->b, b); index->b = b; break; } index->regno = regno; s = new_stmt(BPF_ST); s->s.k = regno; sappend(index->s, s); return index; } struct block * gen_relation(code, a0, a1, reversed) int code; struct arth *a0, *a1; int reversed; { struct slist *s0, *s1, *s2; struct block *b, *tmp; s0 = xfer_to_x(a1); s1 = xfer_to_a(a0); s2 = new_stmt(BPF_ALU|BPF_SUB|BPF_X); b = new_block(JMP(code)); if (code == BPF_JGT || code == BPF_JGE) { reversed = !reversed; b->s.k = 0x80000000; } if (reversed) gen_not(b); sappend(s1, s2); sappend(s0, s1); sappend(a1->s, s0); sappend(a0->s, a1->s); b->stmts = a0->s; free_reg(a0->regno); free_reg(a1->regno); /* 'and' together protocol checks */ if (a0->b) { if (a1->b) { gen_and(a0->b, tmp = a1->b); } else tmp = a0->b; } else tmp = a1->b; if (tmp) gen_and(tmp, b); return b; } struct arth * gen_loadlen() { int regno = alloc_reg(); struct arth *a = (struct arth *)newchunk(sizeof(*a)); struct slist *s; s = new_stmt(BPF_LD|BPF_LEN); s->next = new_stmt(BPF_ST); s->next->s.k = regno; a->s = s; a->regno = regno; return a; } struct arth * gen_loadi(val) int val; { struct arth *a; struct slist *s; int reg; a = (struct arth *)newchunk(sizeof(*a)); reg = alloc_reg(); s = new_stmt(BPF_LD|BPF_IMM); s->s.k = val; s->next = new_stmt(BPF_ST); s->next->s.k = reg; a->s = s; a->regno = reg; return a; } struct arth * gen_neg(a) struct arth *a; { struct slist *s; s = xfer_to_a(a); sappend(a->s, s); s = new_stmt(BPF_ALU|BPF_NEG); s->s.k = 0; sappend(a->s, s); s = new_stmt(BPF_ST); s->s.k = a->regno; sappend(a->s, s); return a; } struct arth * gen_arth(code, a0, a1) int code; struct arth *a0, *a1; { struct slist *s0, *s1, *s2; s0 = xfer_to_x(a1); s1 = xfer_to_a(a0); s2 = new_stmt(BPF_ALU|BPF_X|code); sappend(s1, s2); sappend(s0, s1); sappend(a1->s, s0); sappend(a0->s, a1->s); free_reg(a1->regno); s0 = new_stmt(BPF_ST); a0->regno = s0->s.k = alloc_reg(); sappend(a0->s, s0); return a0; } /* * Here we handle simple allocation of the scratch registers. * If too many registers are alloc'd, the allocator punts. */ static int regused[BPF_MEMWORDS]; static int curreg; /* * Return the next free register. */ static int alloc_reg() { int n = BPF_MEMWORDS; while (--n >= 0) { if (regused[curreg]) curreg = (curreg + 1) % BPF_MEMWORDS; else { regused[curreg] = 1; return curreg; } } bpf_error("too many registers needed to evaluate expression"); /* NOTREACHED */ } /* * Return a register to the table so it can * be used later. */ static void free_reg(n) int n; { regused[n] = 0; } static struct block * gen_len(jmp, n) int jmp, n; { struct slist *s; struct block *b; s = new_stmt(BPF_LD|BPF_LEN); b = new_block(JMP(jmp)); b->stmts = s; b->s.k = n; return b; } struct block * gen_greater(n) int n; { return gen_len(BPF_JGE, n); } struct block * gen_less(n) int n; { struct block *b; b = gen_len(BPF_JGT, n); gen_not(b); return b; } struct block * gen_byteop(op, idx, val) int op, idx, val; { struct block *b; struct slist *s; switch (op) { default: abort(); case '=': return gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); case '<': b = gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); b->s.code = JMP(BPF_JGE); gen_not(b); return b; case '>': b = gen_cmp((u_int)idx, BPF_B, (bpf_int32)val); b->s.code = JMP(BPF_JGT); return b; case '|': s = new_stmt(BPF_ALU|BPF_OR|BPF_K); break; case '&': s = new_stmt(BPF_ALU|BPF_AND|BPF_K); break; } s->s.k = val; b = new_block(JMP(BPF_JEQ)); b->stmts = s; gen_not(b); return b; } struct block * gen_broadcast(proto) int proto; { bpf_u_int32 hostmask; struct block *b0, *b1, *b2; static u_char ebroadcast[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; switch (proto) { case Q_DEFAULT: case Q_LINK: if (linktype == DLT_EN10MB) return gen_ehostop(ebroadcast, Q_DST); if (linktype == DLT_FDDI) return gen_fhostop(ebroadcast, Q_DST); bpf_error("not a broadcast link"); break; case Q_IP: b0 = gen_linktype(ETHERTYPE_IP); hostmask = ~netmask; b1 = gen_mcmp(off_nl + 16, BPF_W, (bpf_int32)0, hostmask); b2 = gen_mcmp(off_nl + 16, BPF_W, (bpf_int32)(~0 & hostmask), hostmask); gen_or(b1, b2); gen_and(b0, b2); return b2; } bpf_error("only ether/ip broadcast filters supported"); } struct block * gen_multicast(proto) int proto; { register struct block *b0, *b1; register struct slist *s; switch (proto) { case Q_DEFAULT: case Q_LINK: if (linktype == DLT_EN10MB) { /* ether[0] & 1 != 0 */ s = new_stmt(BPF_LD|BPF_B|BPF_ABS); s->s.k = 0; b0 = new_block(JMP(BPF_JSET)); b0->s.k = 1; b0->stmts = s; return b0; } if (linktype == DLT_FDDI) { /* XXX TEST THIS: MIGHT NOT PORT PROPERLY XXX */ /* fddi[1] & 1 != 0 */ s = new_stmt(BPF_LD|BPF_B|BPF_ABS); s->s.k = 1; b0 = new_block(JMP(BPF_JSET)); b0->s.k = 1; b0->stmts = s; return b0; } /* Link not known to support multicasts */ break; case Q_IP: b0 = gen_linktype(ETHERTYPE_IP); b1 = gen_cmp(off_nl + 16, BPF_B, (bpf_int32)224); b1->s.code = JMP(BPF_JGE); gen_and(b0, b1); return b1; } bpf_error("only IP multicast filters supported on ethernet/FDDI"); } /* * generate command for inbound/outbound. It's here so we can * make it link-type specific. 'dir' = 0 implies "inbound", * = 1 implies "outbound". */ struct block * gen_inbound(dir) int dir; { register struct block *b0; b0 = gen_relation(BPF_JEQ, gen_load(Q_LINK, gen_loadi(0), 1), gen_loadi(0), dir); return (b0); }