/* 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)
*/
isc_result_t
ns_verify(u_char *msg, unsigned *msglen, void *k,
const u_char *querysig, unsigned querysiglen,
u_char *sig, unsigned *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;
unsigned n;
int error;
u_int16_t type, length;
u_int16_t fudge, sigfieldlen, id, otherfieldlen;
dst_init();
if (msg == NULL || msglen == NULL)
return ISC_R_INVALIDARG;
eom = msg + *msglen;
recstart = ns_find_tsig(msg, eom);
if (recstart == NULL)
return ISC_R_NO_TSIG;
cp = recstart;
/* Read the key name. */
n = dn_expand(msg, eom, cp, name, MAXDNAME);
if (n < 0)
return ISC_R_FORMERR;
cp += n;
/* Read the type. */
BOUNDS_CHECK(cp, 2*INT16SZ + INT32SZ + INT16SZ);
GETSHORT(type, cp);
if (type != ns_t_tsig)
return ISC_R_NO_TSIG;
/* Skip the class and TTL, save the length. */
cp += INT16SZ + INT32SZ;
GETSHORT(length, cp);
if (eom - cp != length)
return ISC_R_FORMERR;
/* Read the algorithm name. */
rdatastart = cp;
n = dn_expand(msg, eom, cp, alg, MAXDNAME);
if (n < 0)
return ISC_R_FORMERR;
if (ns_samename(alg, NS_TSIG_ALG_HMAC_MD5) != 1)
return ISC_R_INVALIDKEY;
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 ISC_R_FORMERR;
/* Verify that the key used is OK. */
if (key != NULL) {
if (key->dk_alg != KEY_HMAC_MD5)
return ISC_R_INVALIDKEY;
if (error != ns_r_badsig && error != ns_r_badkey) {
if (ns_samename(key->dk_key_name, name) != 1)
return ISC_R_INVALIDKEY;
}
}
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];
/* 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,
(unsigned)(recstart - msg), NULL, 0);
/* Digest the key name. */
n = ns_name_ntol(recstart, buf, sizeof(buf));
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_ntol(rdatastart, buf, sizeof(buf));
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,
(unsigned)otherfieldlen + INT16SZ + INT16SZ,
NULL, 0);
n = dst_verify_data(SIG_MODE_FINAL, key, &ctx, NULL, 0,
sigstart, sigfieldlen);
if (n < 0)
return ISC_R_BADSIG;
if (sig != NULL && siglen != NULL) {
if (*siglen < sigfieldlen)
return ISC_R_NOSPACE;
memcpy(sig, sigstart, sigfieldlen);
*siglen = sigfieldlen;
}
} else {
if (sigfieldlen > 0)
return ISC_R_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 ISC_R_BADTIME;
if (nostrip == 0) {
*msglen = recstart - msg;
hp->arcount = htons(ntohs(hp->arcount) - 1);
}
if (error != NOERROR)
return ns_rcode_to_isc (error);
return ISC_R_SUCCESS;
}
int
ns_sign2(u_char *msg, int *msglen, int msgsize, int error, void *k,
const u_char *querysig, int querysiglen, u_char *sig, int *siglen,
time_t in_timesigned, u_char **dnptrs, u_char **lastdnptr)
{
HEADER *hp = (HEADER *)msg;
DST_KEY *key = (DST_KEY *)k;
u_char *cp, *eob;
u_char *lenp;
u_char *alg;
int n;
time_t timesigned;
u_char name[NS_MAXCDNAME];
dst_init();
if (msg == NULL || msglen == NULL || sig == NULL || siglen == NULL)
return (-1);
cp = msg + *msglen;
eob = msg + msgsize;
/* Name. */
if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
n = ns_name_pton(key->dk_key_name, name, sizeof name);
if (n != -1)
n = ns_name_pack(name, cp, eob - cp,
(const u_char **)dnptrs,
(const u_char **)lastdnptr);
} else {
n = ns_name_pton("", name, sizeof name);
if (n != -1)
n = ns_name_pack(name, cp, eob - cp, NULL, NULL);
}
if (n < 0)
return (NS_TSIG_ERROR_NO_SPACE);
cp += n;
/* Type, class, ttl, length (not filled in yet). */
BOUNDS_CHECK(cp, INT16SZ + INT16SZ + INT32SZ + INT16SZ);
PUTSHORT(ns_t_tsig, cp);
PUTSHORT(ns_c_any, cp);
PUTLONG(0, cp); /*%< TTL */
lenp = cp;
cp += 2;
/* Alg. */
if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
if (key->dk_alg != KEY_HMAC_MD5)
return (-ns_r_badkey);
n = dn_comp(NS_TSIG_ALG_HMAC_MD5, cp, eob - cp, NULL, NULL);
}
else
n = dn_comp("", cp, eob - cp, NULL, NULL);
if (n < 0)
return (NS_TSIG_ERROR_NO_SPACE);
alg = cp;
cp += n;
/* Time. */
BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
PUTSHORT(0, cp);
timesigned = time(NULL);
if (error != ns_r_badtime)
PUTLONG(timesigned, cp);
else
PUTLONG(in_timesigned, cp);
PUTSHORT(NS_TSIG_FUDGE, cp);
/* Compute the signature. */
if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
void *ctx;
u_char buf[NS_MAXCDNAME], *cp2;
int n;
dst_sign_data(SIG_MODE_INIT, key, &ctx, NULL, 0, NULL, 0);
/* Digest the query signature, if this is a response. */
if (querysiglen > 0 && querysig != NULL) {
u_int16_t len_n = htons(querysiglen);
dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
(u_char *)&len_n, INT16SZ, NULL, 0);
dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
querysig, querysiglen, NULL, 0);
}
/* Digest the message. */
dst_sign_data(SIG_MODE_UPDATE, key, &ctx, msg, *msglen,
NULL, 0);
/* Digest the key name. */
n = ns_name_ntol(name, buf, sizeof(buf));
INSIST(n > 0);
dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);
/* Digest the class and TTL. */
cp2 = buf;
PUTSHORT(ns_c_any, cp2);
PUTLONG(0, cp2);
dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, cp2-buf,
NULL, 0);
/* Digest the algorithm. */
n = ns_name_ntol(alg, buf, sizeof(buf));
INSIST(n > 0);
dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);
/* Digest the time signed, fudge, error, and other data */
cp2 = buf;
PUTSHORT(0, cp2); /*%< Top 16 bits of time */
if (error != ns_r_badtime)
PUTLONG(timesigned, cp2);
else
PUTLONG(in_timesigned, cp2);
PUTSHORT(NS_TSIG_FUDGE, cp2);
PUTSHORT(error, cp2); /*%< Error */
if (error != ns_r_badtime)
PUTSHORT(0, cp2); /*%< Other data length */
else {
PUTSHORT(INT16SZ+INT32SZ, cp2); /*%< Other data length */
PUTSHORT(0, cp2); /*%< Top 16 bits of time */
PUTLONG(timesigned, cp2);
}
dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, cp2-buf,
NULL, 0);
n = dst_sign_data(SIG_MODE_FINAL, key, &ctx, NULL, 0,
sig, *siglen);
if (n < 0)
return (-ns_r_badkey);
*siglen = n;
} else
*siglen = 0;
/* Add the signature. */
BOUNDS_CHECK(cp, INT16SZ + (*siglen));
PUTSHORT(*siglen, cp);
memcpy(cp, sig, *siglen);
cp += (*siglen);
/* The original message ID & error. */
BOUNDS_CHECK(cp, INT16SZ + INT16SZ);
PUTSHORT(ntohs(hp->id), cp); /*%< already in network order */
PUTSHORT(error, cp);
/* Other data. */
BOUNDS_CHECK(cp, INT16SZ);
if (error != ns_r_badtime)
PUTSHORT(0, cp); /*%< Other data length */
else {
PUTSHORT(INT16SZ+INT32SZ, cp); /*%< Other data length */
BOUNDS_CHECK(cp, INT32SZ+INT16SZ);
PUTSHORT(0, cp); /*%< Top 16 bits of time */
PUTLONG(timesigned, cp);
}
/* Go back and fill in the length. */
PUTSHORT(cp - lenp - INT16SZ, lenp);
hp->arcount = htons(ntohs(hp->arcount) + 1);
*msglen = (cp - msg);
return (0);
}
/* ns_sign
* Parameters:
* msg message to be sent
* msglen input - length of message
* output - length of signed message
* msgsize length of buffer containing message
* error value to put in the error field
* key tsig key used for signing
* querysig (response), the signature in the query
* querysiglen (response), the length of the signature in the query
* sig a buffer to hold the generated signature
* siglen input - length of signature buffer
* output - length of signature
*
* Errors:
* - bad input data (-1)
* - bad key / sign failed (-BADKEY)
* - not enough space (NS_TSIG_ERROR_NO_SPACE)
*/
isc_result_t
ns_sign(u_char *msg, unsigned *msglen, unsigned msgsize, int error, void *k,
const u_char *querysig, unsigned querysiglen, u_char *sig,
unsigned *siglen, time_t in_timesigned)
{
HEADER *hp = (HEADER *)msg;
DST_KEY *key = (DST_KEY *)k;
if(msglen == NULL){
return ISC_R_INVALIDARG;
}
u_char *cp = msg + *msglen, *eob = msg + msgsize;
u_char *lenp;
u_char *name, *alg;
unsigned n;
time_t timesigned;
dst_init();
if (msg == NULL || msglen == NULL || sig == NULL || siglen == NULL)
return ISC_R_INVALIDARG;
/* Name. */
if (key != NULL && error != ns_r_badsig && error != ns_r_badkey)
n = dn_comp(key->dk_key_name,
cp, (unsigned)(eob - cp), NULL, NULL);
else
n = dn_comp("", cp, (unsigned)(eob - cp), NULL, NULL);
name = cp;
cp += n;
/* Type, class, ttl, length (not filled in yet). */
BOUNDS_CHECK(cp, INT16SZ + INT16SZ + INT32SZ + INT16SZ);
PUTSHORT(ns_t_tsig, cp);
PUTSHORT(ns_c_any, cp);
PUTLONG(0, cp); /* TTL */
lenp = cp;
cp += 2;
/* Alg. */
if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
if (key->dk_alg != KEY_HMAC_MD5)
return ISC_R_BADKEY;
n = dn_comp(NS_TSIG_ALG_HMAC_MD5,
cp, (unsigned)(eob - cp), NULL, NULL);
}
else
n = dn_comp("", cp, (unsigned)(eob - cp), NULL, NULL);
if (n < 0)
return ISC_R_NOSPACE;
alg = cp;
cp += n;
/* Time. */
BOUNDS_CHECK(cp, INT16SZ + INT32SZ + INT16SZ);
PUTSHORT(0, cp);
timesigned = time(NULL);
if (error != ns_r_badtime)
PUTLONG(timesigned, cp);
else
PUTLONG(in_timesigned, cp);
PUTSHORT(NS_TSIG_FUDGE, cp);
/* Compute the signature. */
if (key != NULL && error != ns_r_badsig && error != ns_r_badkey) {
void *ctx;
u_char buf[MAXDNAME], *cp2;
unsigned n;
dst_sign_data(SIG_MODE_INIT, key, &ctx, NULL, 0, NULL, 0);
/* Digest the query signature, if this is a response. */
if (querysiglen > 0 && querysig != NULL) {
u_int16_t len_n = htons(querysiglen);
dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
(u_char *)&len_n, INT16SZ, NULL, 0);
dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
querysig, querysiglen, NULL, 0);
}
/* Digest the message. */
dst_sign_data(SIG_MODE_UPDATE, key, &ctx, msg, *msglen,
NULL, 0);
/* Digest the key name. */
n = ns_name_ntol(name, buf, sizeof(buf));
dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);
/* Digest the class and TTL. */
cp2 = buf;
PUTSHORT(ns_c_any, cp2);
PUTLONG(0, cp2);
dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
buf, (unsigned)(cp2-buf), NULL, 0);
/* Digest the algorithm. */
n = ns_name_ntol(alg, buf, sizeof(buf));
dst_sign_data(SIG_MODE_UPDATE, key, &ctx, buf, n, NULL, 0);
/* Digest the time signed, fudge, error, and other data */
cp2 = buf;
PUTSHORT(0, cp2); /* Top 16 bits of time */
if (error != ns_r_badtime)
PUTLONG(timesigned, cp2);
else
PUTLONG(in_timesigned, cp2);
PUTSHORT(NS_TSIG_FUDGE, cp2);
PUTSHORT(error, cp2); /* Error */
if (error != ns_r_badtime)
PUTSHORT(0, cp2); /* Other data length */
else {
PUTSHORT(INT16SZ+INT32SZ, cp2); /* Other data length */
PUTSHORT(0, cp2); /* Top 16 bits of time */
PUTLONG(timesigned, cp2);
}
dst_sign_data(SIG_MODE_UPDATE, key, &ctx,
buf, (unsigned)(cp2-buf), NULL, 0);
n = dst_sign_data(SIG_MODE_FINAL, key, &ctx, NULL, 0,
sig, *siglen);
if (n < 0)
return ISC_R_BADKEY;
*siglen = n;
} else
*siglen = 0;
/* Add the signature. */
BOUNDS_CHECK(cp, INT16SZ + (*siglen));
PUTSHORT(*siglen, cp);
if(*siglen>=0){
memcpy(cp, sig, *siglen);
cp += (*siglen);
}
/* The original message ID & error. */
BOUNDS_CHECK(cp, INT16SZ + INT16SZ);
PUTSHORT(ntohs(hp->id), cp); /* already in network order */
PUTSHORT(error, cp);
/* Other data. */
BOUNDS_CHECK(cp, INT16SZ);
if (error != ns_r_badtime)
PUTSHORT(0, cp); /* Other data length */
else {
PUTSHORT(INT16SZ+INT32SZ, cp); /* Other data length */
BOUNDS_CHECK(cp, INT32SZ+INT16SZ);
PUTSHORT(0, cp); /* Top 16 bits of time */
PUTLONG(timesigned, cp);
}
/* Go back and fill in the length. */
PUTSHORT(cp - lenp - INT16SZ, lenp);
hp->arcount = htons(ntohs(hp->arcount) + 1);
*msglen = (cp - msg);
return ISC_R_SUCCESS;
}
