/* * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") * Copyright (c) 1999 by Internet Software Consortium, Inc. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */#ifndef lintstatic const char rcsid[] = "$Id: ns_verify.c,v 1.1.206.1 2004/03/09 08:33:45 marka Exp $";#endif/* Import. */#include "port_before.h"#include "fd_setsize.h"#include <sys/types.h>#include <sys/param.h>#include <netinet/in.h>#include <arpa/nameser.h>#include <arpa/inet.h>#include <errno.h>#include <netdb.h>#include <resolv.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <time.h>#include <unistd.h>#include <isc/dst.h>#include "port_after.h"/* Private. */#define BOUNDS_CHECK(ptr, count) \	do { \		if ((ptr) + (count) > eom) { \			return (NS_TSIG_ERROR_FORMERR); \		} \	} while (0)/* Public. */u_char *ns_find_tsig(u_char *msg, u_char *eom) {	HEADER *hp = (HEADER *)msg;	int n, type;	u_char *cp = msg, *start;	if (msg == NULL || eom == NULL || msg > eom)		return (NULL);	if (cp + HFIXEDSZ >= eom)		return (NULL);	if (hp->arcount == 0)		return (NULL);	cp += HFIXEDSZ;	n = ns_skiprr(cp, eom, ns_s_qd, ntohs(hp->qdcount));	if (n < 0)		return (NULL);	cp += n;	n = ns_skiprr(cp, eom, ns_s_an, ntohs(hp->ancount));	if (n < 0)		return (NULL);	cp += n;	n = ns_skiprr(cp, eom, ns_s_ns, ntohs(hp->nscount));	if (n < 0)		return (NULL);	cp += n;	n = ns_skiprr(cp, eom, ns_s_ar, ntohs(hp->arcount) - 1);	if (n < 0)		return (NULL);	cp += n;	start = cp;	n = dn_skipname(cp, eom);	if (n < 0)		return (NULL);	cp += n;	if (cp + INT16SZ >= eom)		return (NULL);	GETSHORT(type, cp);	if (type != ns_t_tsig)		return (NULL);	return (start);}/* ns_verify * Parameters: *	statp		res stuff *	msg		received message *	msglen		length of message *	key		tsig key used for verifying. *	querysig	(response), the signature in the query *	querysiglen	(response), the length of the signature in the query *	sig		(query), a buffer to hold the signature *	siglen		(query), input - length of signature buffer *				 output - length of signature * * Errors: *	- bad input (-1) *	- invalid dns message (NS_TSIG_ERROR_FORMERR) *	- TSIG is not present (NS_TSIG_ERROR_NO_TSIG) *	- key doesn't match (-ns_r_badkey) *	- TSIG verification fails with BADKEY (-ns_r_badkey) *	- TSIG verification fails with BADSIG (-ns_r_badsig) *	- TSIG verification fails with BADTIME (-ns_r_badtime) *	- TSIG verification succeeds, error set to BAKEY (ns_r_badkey) *	- TSIG verification succeeds, error set to BADSIG (ns_r_badsig) *	- TSIG verification succeeds, error set to BADTIME (ns_r_badtime) */intns_verify(u_char *msg, int *msglen, void *k,	  const u_char *querysig, int querysiglen, u_char *sig, int *siglen,	  time_t *timesigned, int nostrip){	HEADER *hp = (HEADER *)msg;	DST_KEY *key = (DST_KEY *)k;	u_char *cp = msg, *eom;	char name[MAXDNAME], alg[MAXDNAME];	u_char *recstart, *rdatastart;	u_char *sigstart, *otherstart;	int n;	int error;	u_int16_t type, length;	u_int16_t fudge, sigfieldlen, id, otherfieldlen;	dst_init();	if (msg == NULL || msglen == NULL || *msglen < 0)		return (-1);	eom = msg + *msglen;	recstart = ns_find_tsig(msg, eom);	if (recstart == NULL)		return (NS_TSIG_ERROR_NO_TSIG);	cp = recstart;	/* Read the key name. */	n = dn_expand(msg, eom, cp, name, MAXDNAME);	if (n < 0)		return (NS_TSIG_ERROR_FORMERR);	cp += n;	/* Read the type. */	BOUNDS_CHECK(cp, 2*INT16SZ + INT32SZ + INT16SZ);	GETSHORT(type, cp);	if (type != ns_t_tsig)		return (NS_TSIG_ERROR_NO_TSIG);	/* Skip the class and TTL, save the length. */	cp += INT16SZ + INT32SZ;	GETSHORT(length, cp);	if (eom - cp != length)		return (NS_TSIG_ERROR_FORMERR);	/* Read the algorithm name. */	rdatastart = cp;	n = dn_expand(msg, eom, cp, alg, MAXDNAME);	if (n < 0)		return (NS_TSIG_ERROR_FORMERR);	if (ns_samename(alg, NS_TSIG_ALG_HMAC_MD5) != 1)		return (-ns_r_badkey);	cp += n;	/* Read the time signed and fudge. */	BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);	cp += INT16SZ;	GETLONG((*timesigned), cp);	GETSHORT(fudge, cp);	/* Read the signature. */	BOUNDS_CHECK(cp, INT16SZ);	GETSHORT(sigfieldlen, cp);	BOUNDS_CHECK(cp, sigfieldlen);	sigstart = cp;	cp += sigfieldlen;	/* Read the original id and error. */	BOUNDS_CHECK(cp, 2*INT16SZ);	GETSHORT(id, cp);	GETSHORT(error, cp);	/* Parse the other data. */	BOUNDS_CHECK(cp, INT16SZ);	GETSHORT(otherfieldlen, cp);	BOUNDS_CHECK(cp, otherfieldlen);	otherstart = cp;	cp += otherfieldlen;	if (cp != eom)		return (NS_TSIG_ERROR_FORMERR);	/* Verify that the key used is OK. */	if (key != NULL) {		if (key->dk_alg != KEY_HMAC_MD5)			return (-ns_r_badkey);		if (error != ns_r_badsig && error != ns_r_badkey) {			if (ns_samename(key->dk_key_name, name) != 1)				return (-ns_r_badkey);		}	}	hp->arcount = htons(ntohs(hp->arcount) - 1);	/*	 * Do the verification.	 */	if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {		void *ctx;		u_char buf[MAXDNAME];		u_char buf2[MAXDNAME];		/* Digest the query signature, if this is a response. */		dst_verify_data(SIG_MODE_INIT, key, &ctx, NULL, 0, NULL, 0);		if (querysiglen > 0 && querysig != NULL) {			u_int16_t len_n = htons(querysiglen);			dst_verify_data(SIG_MODE_UPDATE, key, &ctx,					(u_char *)&len_n, INT16SZ, NULL, 0);			dst_verify_data(SIG_MODE_UPDATE, key, &ctx,					querysig, querysiglen, NULL, 0);		}		 		/* Digest the message. */		dst_verify_data(SIG_MODE_UPDATE, key, &ctx, msg, recstart - msg,				NULL, 0);		/* Digest the key name. */		n = ns_name_pton(name, buf2, sizeof(buf2));		if (n < 0)			return (-1);		n = ns_name_ntol(buf2, buf, sizeof(buf));		if (n < 0)			return (-1);		dst_verify_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);		/* Digest the class and TTL. */		dst_verify_data(SIG_MODE_UPDATE, key, &ctx,				recstart + dn_skipname(recstart, eom) + INT16SZ,				INT16SZ + INT32SZ, NULL, 0);		/* Digest the algorithm. */		n = ns_name_pton(alg, buf2, sizeof(buf2));		if (n < 0)			return (-1);		n = ns_name_ntol(buf2, buf, sizeof(buf));		if (n < 0)			return (-1);		dst_verify_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);		/* Digest the time signed and fudge. */		dst_verify_data(SIG_MODE_UPDATE, key, &ctx,				rdatastart + dn_skipname(rdatastart, eom),				INT16SZ + INT32SZ + INT16SZ, NULL, 0);		/* Digest the error and other data. */		dst_verify_data(SIG_MODE_UPDATE, key, &ctx,				otherstart - INT16SZ - INT16SZ,				otherfieldlen + INT16SZ + INT16SZ, NULL, 0);		n = dst_verify_data(SIG_MODE_FINAL, key, &ctx, NULL, 0,				    sigstart, sigfieldlen);		if (n < 0)			return (-ns_r_badsig);		if (sig != NULL && siglen != NULL) {			if (*siglen < sigfieldlen)				return (NS_TSIG_ERROR_NO_SPACE);			memcpy(sig, sigstart, sigfieldlen);			*siglen = sigfieldlen;		}	} else {		if (sigfieldlen > 0)			return (NS_TSIG_ERROR_FORMERR);		if (sig != NULL && siglen != NULL)			*siglen = 0;	}	/* Reset the counter, since we still need to check for badtime. */	hp->arcount = htons(ntohs(hp->arcount) + 1);	/* Verify the time. */	if (abs((*timesigned) - time(NULL)) > fudge)		return (-ns_r_badtime);	if (nostrip == 0) {		*msglen = recstart - msg;		hp->arcount = htons(ntohs(hp->arcount) - 1);	}	if (error != NOERROR)		return (error);	return (0);}intns_verify_tcp_init(void *k, const u_char *querysig, int querysiglen,		   ns_tcp_tsig_state *state){	dst_init();	if (state == NULL || k == NULL || querysig == NULL || querysiglen < 0)		return (-1);	state->counter = -1;	state->key = k;	if (state->key->dk_alg != KEY_HMAC_MD5)		return (-ns_r_badkey);	if (querysiglen > (int)sizeof(state->sig))		return (-1);	memcpy(state->sig, querysig, querysiglen);	state->siglen = querysiglen;	return (0);}intns_verify_tcp(u_char *msg, int *msglen, ns_tcp_tsig_state *state,	      int required){	HEADER *hp = (HEADER *)msg;	u_char *recstart, *rdatastart, *sigstart;	unsigned int sigfieldlen, otherfieldlen;	u_char *cp, *eom = msg + *msglen, *cp2;	char name[MAXDNAME], alg[MAXDNAME];	u_char buf[MAXDNAME];	int n, type, length, fudge, id, error;	time_t timesigned;	if (msg == NULL || msglen == NULL || state == NULL)		return (-1);	state->counter++;	if (state->counter == 0)		return (ns_verify(msg, msglen, state->key,				  state->sig, state->siglen,				  state->sig, &state->siglen, &timesigned, 0));	if (state->siglen > 0) {		u_int16_t siglen_n = htons(state->siglen);		dst_verify_data(SIG_MODE_INIT, state->key, &state->ctx,				NULL, 0, NULL, 0);		dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,				(u_char *)&siglen_n, INT16SZ, NULL, 0);		dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,				state->sig, state->siglen, NULL, 0);		state->siglen = 0;	}	cp = recstart = ns_find_tsig(msg, eom);	if (recstart == NULL) {		if (required)			return (NS_TSIG_ERROR_NO_TSIG);		dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,				msg, *msglen, NULL, 0);		return (0);	}	hp->arcount = htons(ntohs(hp->arcount) - 1);	dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,			msg, recstart - msg, NULL, 0);		/* Read the key name. */	n = dn_expand(msg, eom, cp, name, MAXDNAME);	if (n < 0)		return (NS_TSIG_ERROR_FORMERR);	cp += n;	/* Read the type. */	BOUNDS_CHECK(cp, 2*INT16SZ + INT32SZ + INT16SZ);	GETSHORT(type, cp);	if (type != ns_t_tsig)		return (NS_TSIG_ERROR_NO_TSIG);	/* Skip the class and TTL, save the length. */	cp += INT16SZ + INT32SZ;	GETSHORT(length, cp);	if (eom - cp != length)		return (NS_TSIG_ERROR_FORMERR);	/* Read the algorithm name. */	rdatastart = cp;	n = dn_expand(msg, eom, cp, alg, MAXDNAME);	if (n < 0)		return (NS_TSIG_ERROR_FORMERR);	if (ns_samename(alg, NS_TSIG_ALG_HMAC_MD5) != 1)		return (-ns_r_badkey);	cp += n;	/* Verify that the key used is OK. */	if ((ns_samename(state->key->dk_key_name, name) != 1 ||	     state->key->dk_alg != KEY_HMAC_MD5))		return (-ns_r_badkey);	/* Read the time signed and fudge. */	BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);	cp += INT16SZ;	GETLONG(timesigned, cp);	GETSHORT(fudge, cp);	/* Read the signature. */	BOUNDS_CHECK(cp, INT16SZ);	GETSHORT(sigfieldlen, cp);	BOUNDS_CHECK(cp, sigfieldlen);	sigstart = cp;	cp += sigfieldlen;	/* Read the original id and error. */	BOUNDS_CHECK(cp, 2*INT16SZ);	GETSHORT(id, cp);	GETSHORT(error, cp);	/* Parse the other data. */	BOUNDS_CHECK(cp, INT16SZ);	GETSHORT(otherfieldlen, cp);	BOUNDS_CHECK(cp, otherfieldlen);	cp += otherfieldlen;	if (cp != eom)		return (NS_TSIG_ERROR_FORMERR);	/*	 * Do the verification.	 */	/* Digest the time signed and fudge. */	cp2 = buf;	PUTSHORT(0, cp2);       /* Top 16 bits of time. */	PUTLONG(timesigned, cp2);	PUTSHORT(NS_TSIG_FUDGE, cp2);	dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,			buf, cp2 - buf, NULL, 0);	n = dst_verify_data(SIG_MODE_FINAL, state->key, &state->ctx, NULL, 0,			    sigstart, sigfieldlen);	if (n < 0)		return (-ns_r_badsig);	if (sigfieldlen > sizeof(state->sig))		return (NS_TSIG_ERROR_NO_SPACE);	memcpy(state->sig, sigstart, sigfieldlen);	state->siglen = sigfieldlen;	/* Verify the time. */	if (abs(timesigned - time(NULL)) > fudge)		return (-ns_r_badtime);	*msglen = recstart - msg;	if (error != NOERROR)		return (error);	return (0);}