470 lines
12 KiB
C
470 lines
12 KiB
C
/*
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* Copyright (c) 1999 by Internet Software Consortium, Inc.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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#ifndef lint
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static const char rcsid[] = "$Id: ns_verify.c,v 1.1.1.1 2000/04/22 07:11:54 mellon Exp $";
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#endif
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/* Import. */
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#include <sys/types.h>
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#include <sys/param.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <sys/socket.h>
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#include <errno.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <time.h>
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#include "minires/minires.h"
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#include "arpa/nameser.h"
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#include <isc/dst.h>
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/* Private. */
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#define BOUNDS_CHECK(ptr, count) \
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do { \
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if ((ptr) + (count) > eom) { \
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return (NS_TSIG_ERROR_FORMERR); \
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} \
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} while (0)
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/* Public. */
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u_char *
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ns_find_tsig(u_char *msg, u_char *eom) {
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HEADER *hp = (HEADER *)msg;
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int n, type;
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u_char *cp = msg, *start;
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if (msg == NULL || eom == NULL || msg > eom)
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return (NULL);
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if (cp + HFIXEDSZ >= eom)
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return (NULL);
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if (hp->arcount == 0)
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return (NULL);
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cp += HFIXEDSZ;
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n = ns_skiprr(cp, eom, ns_s_qd, ntohs(hp->qdcount));
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if (n < 0)
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return (NULL);
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cp += n;
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n = ns_skiprr(cp, eom, ns_s_an, ntohs(hp->ancount));
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if (n < 0)
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return (NULL);
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cp += n;
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n = ns_skiprr(cp, eom, ns_s_ns, ntohs(hp->nscount));
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if (n < 0)
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return (NULL);
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cp += n;
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n = ns_skiprr(cp, eom, ns_s_ar, ntohs(hp->arcount) - 1);
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if (n < 0)
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return (NULL);
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cp += n;
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start = cp;
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n = dn_skipname(cp, eom);
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if (n < 0)
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return (NULL);
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cp += n;
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if (cp + INT16SZ >= eom)
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return (NULL);
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GETSHORT(type, cp);
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if (type != ns_t_tsig)
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return (NULL);
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return (start);
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}
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/* ns_verify
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* Parameters:
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* statp res stuff
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* msg received message
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* msglen length of message
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* key tsig key used for verifying.
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* querysig (response), the signature in the query
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* querysiglen (response), the length of the signature in the query
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* sig (query), a buffer to hold the signature
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* siglen (query), input - length of signature buffer
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* output - length of signature
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*
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* Errors:
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* - bad input (-1)
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* - invalid dns message (NS_TSIG_ERROR_FORMERR)
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* - TSIG is not present (NS_TSIG_ERROR_NO_TSIG)
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* - key doesn't match (-ns_r_badkey)
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* - TSIG verification fails with BADKEY (-ns_r_badkey)
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* - TSIG verification fails with BADSIG (-ns_r_badsig)
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* - TSIG verification fails with BADTIME (-ns_r_badtime)
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* - TSIG verification succeeds, error set to BAKEY (ns_r_badkey)
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* - TSIG verification succeeds, error set to BADSIG (ns_r_badsig)
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* - TSIG verification succeeds, error set to BADTIME (ns_r_badtime)
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*/
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int
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ns_verify(u_char *msg, unsigned *msglen, void *k,
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const u_char *querysig, unsigned querysiglen,
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u_char *sig, unsigned *siglen, time_t *timesigned, int nostrip)
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{
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HEADER *hp = (HEADER *)msg;
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DST_KEY *key = (DST_KEY *)k;
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u_char *cp = msg, *eom;
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char name[MAXDNAME], alg[MAXDNAME];
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u_char *recstart, *rdatastart;
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u_char *sigstart, *otherstart;
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unsigned n;
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int error;
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u_int16_t type, length;
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u_int16_t fudge, sigfieldlen, id, otherfieldlen;
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dst_init();
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if (msg == NULL || msglen == NULL || *msglen < 0)
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return (-1);
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eom = msg + *msglen;
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recstart = ns_find_tsig(msg, eom);
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if (recstart == NULL)
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return (NS_TSIG_ERROR_NO_TSIG);
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cp = recstart;
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/* Read the key name. */
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n = dn_expand(msg, eom, cp, name, MAXDNAME);
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if (n < 0)
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return (NS_TSIG_ERROR_FORMERR);
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cp += n;
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/* Read the type. */
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BOUNDS_CHECK(cp, 2*INT16SZ + INT32SZ + INT16SZ);
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GETSHORT(type, cp);
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if (type != ns_t_tsig)
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return (NS_TSIG_ERROR_NO_TSIG);
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/* Skip the class and TTL, save the length. */
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cp += INT16SZ + INT32SZ;
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GETSHORT(length, cp);
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if (eom - cp != length)
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return (NS_TSIG_ERROR_FORMERR);
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/* Read the algorithm name. */
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rdatastart = cp;
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n = dn_expand(msg, eom, cp, alg, MAXDNAME);
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if (n < 0)
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return (NS_TSIG_ERROR_FORMERR);
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if (ns_samename(alg, NS_TSIG_ALG_HMAC_MD5) != 1)
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return (-ns_r_badkey);
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cp += n;
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/* Read the time signed and fudge. */
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BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
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cp += INT16SZ;
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GETLONG((*timesigned), cp);
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GETSHORT(fudge, cp);
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/* Read the signature. */
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BOUNDS_CHECK(cp, INT16SZ);
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GETSHORT(sigfieldlen, cp);
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BOUNDS_CHECK(cp, sigfieldlen);
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sigstart = cp;
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cp += sigfieldlen;
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/* Read the original id and error. */
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BOUNDS_CHECK(cp, 2*INT16SZ);
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GETSHORT(id, cp);
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GETSHORT(error, cp);
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/* Parse the other data. */
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BOUNDS_CHECK(cp, INT16SZ);
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GETSHORT(otherfieldlen, cp);
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BOUNDS_CHECK(cp, otherfieldlen);
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otherstart = cp;
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cp += otherfieldlen;
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if (cp != eom)
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return (NS_TSIG_ERROR_FORMERR);
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/* Verify that the key used is OK. */
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if (key != NULL) {
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if (key->dk_alg != KEY_HMAC_MD5)
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return (-ns_r_badkey);
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if (error != ns_r_badsig && error != ns_r_badkey) {
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if (ns_samename(key->dk_key_name, name) != 1)
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return (-ns_r_badkey);
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}
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}
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hp->arcount = htons(ntohs(hp->arcount) - 1);
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/*
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* Do the verification.
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*/
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if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
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void *ctx;
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u_char buf[MAXDNAME];
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/* Digest the query signature, if this is a response. */
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dst_verify_data(SIG_MODE_INIT, key, &ctx, NULL, 0, NULL, 0);
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if (querysiglen > 0 && querysig != NULL) {
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u_int16_t len_n = htons(querysiglen);
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dst_verify_data(SIG_MODE_UPDATE, key, &ctx,
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(u_char *)&len_n, INT16SZ, NULL, 0);
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dst_verify_data(SIG_MODE_UPDATE, key, &ctx,
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querysig, querysiglen, NULL, 0);
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}
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/* Digest the message. */
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dst_verify_data(SIG_MODE_UPDATE, key, &ctx, msg,
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(unsigned)(recstart - msg), NULL, 0);
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/* Digest the key name. */
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n = ns_name_ntol(recstart, buf, sizeof(buf));
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dst_verify_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);
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/* Digest the class and TTL. */
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dst_verify_data(SIG_MODE_UPDATE, key, &ctx,
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recstart + dn_skipname(recstart, eom) + INT16SZ,
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INT16SZ + INT32SZ, NULL, 0);
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/* Digest the algorithm. */
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n = ns_name_ntol(rdatastart, buf, sizeof(buf));
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dst_verify_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);
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/* Digest the time signed and fudge. */
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dst_verify_data(SIG_MODE_UPDATE, key, &ctx,
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rdatastart + dn_skipname(rdatastart, eom),
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INT16SZ + INT32SZ + INT16SZ, NULL, 0);
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/* Digest the error and other data. */
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dst_verify_data(SIG_MODE_UPDATE, key, &ctx,
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otherstart - INT16SZ - INT16SZ,
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(unsigned)otherfieldlen + INT16SZ + INT16SZ,
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NULL, 0);
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n = dst_verify_data(SIG_MODE_FINAL, key, &ctx, NULL, 0,
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sigstart, sigfieldlen);
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if (n < 0)
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return (-ns_r_badsig);
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if (sig != NULL && siglen != NULL) {
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if (*siglen < sigfieldlen)
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return (NS_TSIG_ERROR_NO_SPACE);
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memcpy(sig, sigstart, sigfieldlen);
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*siglen = sigfieldlen;
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}
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} else {
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if (sigfieldlen > 0)
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return (NS_TSIG_ERROR_FORMERR);
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if (sig != NULL && siglen != NULL)
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*siglen = 0;
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}
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/* Reset the counter, since we still need to check for badtime. */
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hp->arcount = htons(ntohs(hp->arcount) + 1);
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/* Verify the time. */
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if (abs((*timesigned) - time(NULL)) > fudge)
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return (-ns_r_badtime);
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if (nostrip == 0) {
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*msglen = recstart - msg;
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hp->arcount = htons(ntohs(hp->arcount) - 1);
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}
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if (error != NOERROR)
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return (error);
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return (0);
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}
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int
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ns_verify_tcp_init(void *k, const u_char *querysig, unsigned querysiglen,
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ns_tcp_tsig_state *state)
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{
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dst_init();
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if (state == NULL || k == NULL || querysig == NULL || querysiglen < 0)
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return (-1);
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state->counter = -1;
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state->key = k;
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if (state->key->dk_alg != KEY_HMAC_MD5)
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return (-ns_r_badkey);
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if (querysiglen > sizeof(state->sig))
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return (-1);
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memcpy(state->sig, querysig, querysiglen);
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state->siglen = querysiglen;
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return (0);
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}
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int
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ns_verify_tcp(u_char *msg, unsigned *msglen, ns_tcp_tsig_state *state,
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int required)
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{
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HEADER *hp = (HEADER *)msg;
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u_char *recstart, *rdatastart, *sigstart;
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unsigned sigfieldlen, otherfieldlen;
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u_char *cp, *eom = msg + *msglen, *cp2;
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char name[MAXDNAME], alg[MAXDNAME];
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u_char buf[MAXDNAME];
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int n, type, length, fudge, id, error;
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time_t timesigned;
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if (msg == NULL || msglen == NULL || state == NULL)
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return (-1);
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state->counter++;
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if (state->counter == 0)
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return (ns_verify(msg, msglen, state->key,
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state->sig, state->siglen,
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state->sig, &state->siglen, ×igned, 0));
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if (state->siglen > 0) {
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u_int16_t siglen_n = htons(state->siglen);
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dst_verify_data(SIG_MODE_INIT, state->key, &state->ctx,
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NULL, 0, NULL, 0);
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dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,
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(u_char *)&siglen_n, INT16SZ, NULL, 0);
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dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,
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state->sig, state->siglen, NULL, 0);
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state->siglen = 0;
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}
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cp = recstart = ns_find_tsig(msg, eom);
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if (recstart == NULL) {
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if (required)
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return (NS_TSIG_ERROR_NO_TSIG);
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dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,
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msg, *msglen, NULL, 0);
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return (0);
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}
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hp->arcount = htons(ntohs(hp->arcount) - 1);
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dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,
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msg, (unsigned)(recstart - msg), NULL, 0);
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/* Read the key name. */
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n = dn_expand(msg, eom, cp, name, MAXDNAME);
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if (n < 0)
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return (NS_TSIG_ERROR_FORMERR);
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cp += n;
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/* Read the type. */
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BOUNDS_CHECK(cp, 2*INT16SZ + INT32SZ + INT16SZ);
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GETSHORT(type, cp);
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if (type != ns_t_tsig)
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return (NS_TSIG_ERROR_NO_TSIG);
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/* Skip the class and TTL, save the length. */
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cp += INT16SZ + INT32SZ;
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GETSHORT(length, cp);
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if (eom - cp != length)
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return (NS_TSIG_ERROR_FORMERR);
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/* Read the algorithm name. */
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rdatastart = cp;
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n = dn_expand(msg, eom, cp, alg, MAXDNAME);
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if (n < 0)
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return (NS_TSIG_ERROR_FORMERR);
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if (ns_samename(alg, NS_TSIG_ALG_HMAC_MD5) != 1)
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return (-ns_r_badkey);
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cp += n;
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/* Verify that the key used is OK. */
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if ((ns_samename(state->key->dk_key_name, name) != 1 ||
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state->key->dk_alg != KEY_HMAC_MD5))
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return (-ns_r_badkey);
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/* Read the time signed and fudge. */
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BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
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cp += INT16SZ;
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GETLONG(timesigned, cp);
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GETSHORT(fudge, cp);
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/* Read the signature. */
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BOUNDS_CHECK(cp, INT16SZ);
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GETSHORT(sigfieldlen, cp);
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BOUNDS_CHECK(cp, sigfieldlen);
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sigstart = cp;
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cp += sigfieldlen;
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/* Read the original id and error. */
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BOUNDS_CHECK(cp, 2*INT16SZ);
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GETSHORT(id, cp);
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GETSHORT(error, cp);
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/* Parse the other data. */
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BOUNDS_CHECK(cp, INT16SZ);
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GETSHORT(otherfieldlen, cp);
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BOUNDS_CHECK(cp, otherfieldlen);
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cp += otherfieldlen;
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if (cp != eom)
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return (NS_TSIG_ERROR_FORMERR);
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/*
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* Do the verification.
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*/
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/* Digest the time signed and fudge. */
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cp2 = buf;
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PUTSHORT(0, cp2); /* Top 16 bits of time. */
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PUTLONG(timesigned, cp2);
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PUTSHORT(NS_TSIG_FUDGE, cp2);
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dst_verify_data(SIG_MODE_UPDATE, state->key, &state->ctx,
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buf, (unsigned)(cp2 - buf), NULL, 0);
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n = dst_verify_data(SIG_MODE_FINAL, state->key, &state->ctx, NULL, 0,
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sigstart, sigfieldlen);
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if (n < 0)
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return (-ns_r_badsig);
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if (sigfieldlen > sizeof(state->sig))
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return (ns_r_badsig);
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if (sigfieldlen > sizeof(state->sig))
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return (NS_TSIG_ERROR_NO_SPACE);
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memcpy(state->sig, sigstart, sigfieldlen);
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state->siglen = sigfieldlen;
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/* Verify the time. */
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if (abs(timesigned - time(NULL)) > fudge)
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return (-ns_r_badtime);
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*msglen = recstart - msg;
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if (error != NOERROR)
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return (error);
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return (0);
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}
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