tsig.c

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/*
 * tsig.c
 *
 * contains the functions needed for TSIG [RFC2845]
 *
 * (c) 2005-2006 NLnet Labs
 * See the file LICENSE for the license
 */
 
#include <ldns/config.h>
 
#include <ldns/ldns.h>
 
#include <strings.h>
 
#ifdef HAVE_SSL
#include <openssl/hmac.h>
#include <openssl/md5.h>
#endif /* HAVE_SSL */
 
const char *
ldns_tsig_algorithm(const ldns_tsig_credentials *tc)
{
        return tc->algorithm;
}
 
const char *
ldns_tsig_keyname(const ldns_tsig_credentials *tc)
{
        return tc->keyname;
}
 
const char *
ldns_tsig_keydata(const ldns_tsig_credentials *tc)
{
        return tc->keydata;
}
 
char *
ldns_tsig_keyname_clone(const ldns_tsig_credentials *tc)
{
        return strdup(tc->keyname);
}
 
char *
ldns_tsig_keydata_clone(const ldns_tsig_credentials *tc)
{
        return strdup(tc->keydata);
}
 
/*
 *  Makes an exact copy of the wire, but with the tsig rr removed
 */
static uint8_t *
ldns_tsig_prepare_pkt_wire(const uint8_t *wire, size_t wire_len, size_t *result_len)
{
        uint8_t *wire2 = NULL;
        uint16_t qd_count;
        uint16_t an_count;
        uint16_t ns_count;
        uint16_t ar_count;
        ldns_rr *rr;
 
        size_t pos;
        uint16_t i;
 
        ldns_status status;
 
        if(wire_len < LDNS_HEADER_SIZE) {
                return NULL;
        }
        /* fake parse the wire */
        qd_count = LDNS_QDCOUNT(wire);
        an_count = LDNS_ANCOUNT(wire);
        ns_count = LDNS_NSCOUNT(wire);
        ar_count = LDNS_ARCOUNT(wire);
 
        if (ar_count > 0) {
                ar_count--;
        } else {
                return NULL;
        }
 
        pos = LDNS_HEADER_SIZE;
 
        for (i = 0; i < qd_count; i++) {
                status = ldns_wire2rr(&rr, wire, wire_len, &pos, LDNS_SECTION_QUESTION);
                if (status != LDNS_STATUS_OK) {
                        return NULL;
                }
                ldns_rr_free(rr);
        }
 
        for (i = 0; i < an_count; i++) {
                status = ldns_wire2rr(&rr, wire, wire_len, &pos, LDNS_SECTION_ANSWER);
                if (status != LDNS_STATUS_OK) {
                        return NULL;
                }
                ldns_rr_free(rr);
        }
 
        for (i = 0; i < ns_count; i++) {
                status = ldns_wire2rr(&rr, wire, wire_len, &pos, LDNS_SECTION_AUTHORITY);
                if (status != LDNS_STATUS_OK) {
                        return NULL;
                }
                ldns_rr_free(rr);
        }
 
        for (i = 0; i < ar_count; i++) {
                status = ldns_wire2rr(&rr, wire, wire_len, &pos,
                                LDNS_SECTION_ADDITIONAL);
                if (status != LDNS_STATUS_OK) {
                        return NULL;
                }
                ldns_rr_free(rr);
        }
 
        *result_len = pos;
        wire2 = LDNS_XMALLOC(uint8_t, *result_len);
        if(!wire2) {
                return NULL;
        }
        memcpy(wire2, wire, *result_len);
 
        ldns_write_uint16(wire2 + LDNS_ARCOUNT_OFF, ar_count);
 
        return wire2;
}
 
#ifdef HAVE_SSL
static const EVP_MD *
ldns_digest_function(char *name)
{
        /* these are the mandatory algorithms from RFC4635 */
        /* The optional algorithms are not yet implemented */
        if (strcasecmp(name, "hmac-sha512.") == 0) {
#ifdef HAVE_EVP_SHA512
                return EVP_sha512();
#else
                return NULL;
#endif
        } else if (strcasecmp(name, "hmac-shac384.") == 0) {
#ifdef HAVE_EVP_SHA384
                return EVP_sha384();
#else
                return NULL;
#endif
        } else if (strcasecmp(name, "hmac-sha256.") == 0) {
#ifdef HAVE_EVP_SHA256
                return EVP_sha256();
#else
                return NULL;
#endif
        } else if (strcasecmp(name, "hmac-sha1.") == 0) {
                return EVP_sha1();
        } else if (strcasecmp(name, "hmac-md5.sig-alg.reg.int.") == 0) {
                return EVP_md5();
        } else {
                return NULL;
        }
}
#endif
 
#ifdef HAVE_SSL
static ldns_status
ldns_tsig_mac_new(ldns_rdf **tsig_mac, const uint8_t *pkt_wire, size_t pkt_wire_size,
                const char *key_data, const ldns_rdf *key_name_rdf, const ldns_rdf *fudge_rdf,
                const ldns_rdf *algorithm_rdf, const ldns_rdf *time_signed_rdf, const ldns_rdf *error_rdf,
                const ldns_rdf *other_data_rdf, const ldns_rdf *orig_mac_rdf, int tsig_timers_only)
{
        ldns_status status;
        char *wireformat;
        int wiresize;
        unsigned char *mac_bytes = NULL;
        unsigned char *key_bytes = NULL;
        int key_size;
        const EVP_MD *digester;
        char *algorithm_name = NULL;
        unsigned int md_len = EVP_MAX_MD_SIZE;
        ldns_rdf *result = NULL;
        ldns_buffer *data_buffer = NULL;
        ldns_rdf *canonical_key_name_rdf = NULL;
        ldns_rdf *canonical_algorithm_rdf = NULL;
        
        if (key_name_rdf == NULL || algorithm_rdf == NULL) {
                return LDNS_STATUS_NULL;
        }
        canonical_key_name_rdf  = ldns_rdf_clone(key_name_rdf);
        if (canonical_key_name_rdf == NULL) {
                return LDNS_STATUS_MEM_ERR;
        }
        canonical_algorithm_rdf = ldns_rdf_clone(algorithm_rdf);
        if (canonical_algorithm_rdf == NULL) {
                ldns_rdf_deep_free(canonical_key_name_rdf);
                return LDNS_STATUS_MEM_ERR;
        }
        /*
         * prepare the digestible information
         */
        data_buffer = ldns_buffer_new(LDNS_MAX_PACKETLEN);
        if (!data_buffer) {
                status = LDNS_STATUS_MEM_ERR;
                goto clean;
        }
        /* if orig_mac is not NULL, add it too */
        if (orig_mac_rdf) {
                (void) ldns_rdf2buffer_wire(data_buffer, orig_mac_rdf);
        }
        ldns_buffer_write(data_buffer, pkt_wire, pkt_wire_size);
        if (!tsig_timers_only) {
                ldns_dname2canonical(canonical_key_name_rdf);
                (void)ldns_rdf2buffer_wire(data_buffer, 
                                canonical_key_name_rdf);
                ldns_buffer_write_u16(data_buffer, LDNS_RR_CLASS_ANY);
                ldns_buffer_write_u32(data_buffer, 0);
                ldns_dname2canonical(canonical_algorithm_rdf);
                (void)ldns_rdf2buffer_wire(data_buffer, 
                                canonical_algorithm_rdf);
        }
        (void)ldns_rdf2buffer_wire(data_buffer, time_signed_rdf);
        (void)ldns_rdf2buffer_wire(data_buffer, fudge_rdf);
        if (!tsig_timers_only) {
                (void)ldns_rdf2buffer_wire(data_buffer, error_rdf);
                (void)ldns_rdf2buffer_wire(data_buffer, other_data_rdf);
        }
 
        wireformat = (char *) data_buffer->_data;
        wiresize = (int) ldns_buffer_position(data_buffer);
 
        algorithm_name = ldns_rdf2str(algorithm_rdf);
        if(!algorithm_name) {
                status = LDNS_STATUS_MEM_ERR;
                goto clean;
        }
 
        /* prepare the key */
        key_bytes = LDNS_XMALLOC(unsigned char,
                        ldns_b64_pton_calculate_size(strlen(key_data)));
        if(!key_bytes) {
                status = LDNS_STATUS_MEM_ERR;
                goto clean;
        }
        key_size = ldns_b64_pton(key_data, key_bytes,
        ldns_b64_pton_calculate_size(strlen(key_data)));
        if (key_size < 0) {
                status = LDNS_STATUS_INVALID_B64;
                goto clean;
        }
        /* hmac it */
        /* 2 spare bytes for the length */
        mac_bytes = LDNS_XMALLOC(unsigned char, md_len+2);
        if(!mac_bytes) {
                status = LDNS_STATUS_MEM_ERR;
                goto clean;
        }
        memset(mac_bytes, 0, md_len+2);
 
        digester = ldns_digest_function(algorithm_name);
 
        if (digester) {
                (void) HMAC(digester, key_bytes, key_size, (void *)wireformat,
                            (size_t) wiresize, mac_bytes + 2, &md_len);
 
                ldns_write_uint16(mac_bytes, md_len);
                result = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_INT16_DATA, md_len + 2,
                                mac_bytes);
        } else {
                status = LDNS_STATUS_CRYPTO_UNKNOWN_ALGO;
                goto clean;
        }
        *tsig_mac = result;
        status = LDNS_STATUS_OK;
  clean:
        LDNS_FREE(mac_bytes);
        LDNS_FREE(key_bytes);
        LDNS_FREE(algorithm_name);
        ldns_buffer_free(data_buffer);
        ldns_rdf_deep_free(canonical_algorithm_rdf);
        ldns_rdf_deep_free(canonical_key_name_rdf);
        return status;
}
#endif /*  HAVE_SSL */
 
 
#ifdef HAVE_SSL
bool
ldns_pkt_tsig_verify(ldns_pkt *pkt, const uint8_t *wire, size_t wirelen, const char *key_name,
        const char *key_data, const ldns_rdf *orig_mac_rdf)
{
        return ldns_pkt_tsig_verify_next(pkt, wire, wirelen, key_name, key_data, orig_mac_rdf, 0);
}
 
bool
ldns_pkt_tsig_verify_next(ldns_pkt *pkt, const uint8_t *wire, size_t wirelen, const char* key_name,
        const char *key_data, const ldns_rdf *orig_mac_rdf, int tsig_timers_only)
{
        ldns_rdf *fudge_rdf;
        ldns_rdf *algorithm_rdf;
        ldns_rdf *time_signed_rdf;
        ldns_rdf *orig_id_rdf;
        ldns_rdf *error_rdf;
        ldns_rdf *other_data_rdf;
        ldns_rdf *pkt_mac_rdf;
        ldns_rdf *my_mac_rdf;
        ldns_rdf *key_name_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, key_name);
        uint16_t pkt_id, orig_pkt_id;
        ldns_status status;
 
        uint8_t *prepared_wire = NULL;
        size_t prepared_wire_size = 0;
 
        ldns_rr *orig_tsig = ldns_pkt_tsig(pkt);
 
        if (!orig_tsig || ldns_rr_rd_count(orig_tsig) <= 6) {
                ldns_rdf_deep_free(key_name_rdf);
                return false;
        }
        algorithm_rdf = ldns_rr_rdf(orig_tsig, 0);
        time_signed_rdf = ldns_rr_rdf(orig_tsig, 1);
        fudge_rdf = ldns_rr_rdf(orig_tsig, 2);
        pkt_mac_rdf = ldns_rr_rdf(orig_tsig, 3);
        orig_id_rdf = ldns_rr_rdf(orig_tsig, 4);
        error_rdf = ldns_rr_rdf(orig_tsig, 5);
        other_data_rdf = ldns_rr_rdf(orig_tsig, 6);
 
        /* remove temporarily */
        ldns_pkt_set_tsig(pkt, NULL);
        /* temporarily change the id to the original id */
        pkt_id = ldns_pkt_id(pkt);
        orig_pkt_id = ldns_rdf2native_int16(orig_id_rdf);
        ldns_pkt_set_id(pkt, orig_pkt_id);
 
        prepared_wire = ldns_tsig_prepare_pkt_wire(wire, wirelen, &prepared_wire_size);
 
        status = ldns_tsig_mac_new(&my_mac_rdf, prepared_wire, prepared_wire_size,
                        key_data, key_name_rdf, fudge_rdf, algorithm_rdf,
                        time_signed_rdf, error_rdf, other_data_rdf, orig_mac_rdf, tsig_timers_only);
 
        LDNS_FREE(prepared_wire);
 
        if (status != LDNS_STATUS_OK) {
                ldns_rdf_deep_free(key_name_rdf);
                return false;
        }
        /* Put back the values */
        ldns_pkt_set_tsig(pkt, orig_tsig);
        ldns_pkt_set_id(pkt, pkt_id);
 
        ldns_rdf_deep_free(key_name_rdf);
 
        if( ldns_rdf_size(pkt_mac_rdf) != ldns_rdf_size(my_mac_rdf)) {
                ldns_rdf_deep_free(my_mac_rdf);
                return false;
        }
        /* use time insensitive memory compare */
        if(
#ifdef HAVE_CRYPTO_MEMCMP
            CRYPTO_memcmp
#else
            memcmp
#endif
                (ldns_rdf_data(pkt_mac_rdf), ldns_rdf_data(my_mac_rdf),
                ldns_rdf_size(my_mac_rdf)) == 0) {
                ldns_rdf_deep_free(my_mac_rdf);
                return true;
        } else {
                ldns_rdf_deep_free(my_mac_rdf);
                return false;
        }
}
#endif /* HAVE_SSL */
 
#ifdef HAVE_SSL
ldns_status
ldns_pkt_tsig_sign(ldns_pkt *pkt, const char *key_name, const char *key_data,
        uint16_t fudge, const char *algorithm_name, const ldns_rdf *query_mac)
{
        return ldns_pkt_tsig_sign_next(pkt, key_name, key_data, fudge, algorithm_name, query_mac, 0);
}
 
ldns_status
ldns_pkt_tsig_sign_next(ldns_pkt *pkt, const char *key_name, const char *key_data,
        uint16_t fudge, const char *algorithm_name, const ldns_rdf *query_mac, int tsig_timers_only)
{
        ldns_rr *tsig_rr;
        ldns_rdf *key_name_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, key_name);
        ldns_rdf *fudge_rdf = NULL;
        ldns_rdf *orig_id_rdf = NULL;
        ldns_rdf *algorithm_rdf;
        ldns_rdf *error_rdf = NULL;
        ldns_rdf *mac_rdf = NULL;
        ldns_rdf *other_data_rdf = NULL;
 
        ldns_status status = LDNS_STATUS_OK;
 
        uint8_t *pkt_wire = NULL;
        size_t pkt_wire_len;
 
        struct timeval tv_time_signed;
        uint8_t *time_signed = NULL;
        ldns_rdf *time_signed_rdf = NULL;
 
        algorithm_rdf = ldns_rdf_new_frm_str(LDNS_RDF_TYPE_DNAME, algorithm_name);
        if(!key_name_rdf || !algorithm_rdf) {
                status = LDNS_STATUS_MEM_ERR;
                goto clean;
        }
 
        /* eww don't have create tsigtime rdf yet :( */
        /* bleh :p */
        if (gettimeofday(&tv_time_signed, NULL) == 0) {
                time_signed = LDNS_XMALLOC(uint8_t, 6);
                if(!time_signed) {
                        status = LDNS_STATUS_MEM_ERR;
                        goto clean;
                }
                ldns_write_uint64_as_uint48(time_signed,
                                (uint64_t)tv_time_signed.tv_sec);
        } else {
                status = LDNS_STATUS_INTERNAL_ERR;
                goto clean;
        }
 
        time_signed_rdf = ldns_rdf_new(LDNS_RDF_TYPE_TSIGTIME, 6, time_signed);
        if(!time_signed_rdf) {
                LDNS_FREE(time_signed);
                status = LDNS_STATUS_MEM_ERR;
                goto clean;
        }
 
        fudge_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, fudge);
 
        orig_id_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, ldns_pkt_id(pkt));
 
        error_rdf = ldns_native2rdf_int16(LDNS_RDF_TYPE_INT16, 0);
 
        other_data_rdf = ldns_native2rdf_int16_data(0, NULL);
 
        if(!fudge_rdf || !orig_id_rdf || !error_rdf || !other_data_rdf) {
                status = LDNS_STATUS_MEM_ERR;
                goto clean;
        }
 
        if (ldns_pkt2wire(&pkt_wire, pkt, &pkt_wire_len) != LDNS_STATUS_OK) {
                status = LDNS_STATUS_ERR;
                goto clean;
        }
 
        status = ldns_tsig_mac_new(&mac_rdf, pkt_wire, pkt_wire_len,
                        key_data, key_name_rdf, fudge_rdf, algorithm_rdf,
                        time_signed_rdf, error_rdf, other_data_rdf, query_mac, tsig_timers_only);
 
        if (!mac_rdf) {
                goto clean;
        }
 
        LDNS_FREE(pkt_wire);
 
        /* Create the TSIG RR */
        tsig_rr = ldns_rr_new();
        if(!tsig_rr) {
                status = LDNS_STATUS_MEM_ERR;
                goto clean;
        }
        ldns_rr_set_owner(tsig_rr, key_name_rdf);
        ldns_rr_set_class(tsig_rr, LDNS_RR_CLASS_ANY);
        ldns_rr_set_type(tsig_rr, LDNS_RR_TYPE_TSIG);
        ldns_rr_set_ttl(tsig_rr, 0);
 
        ldns_rr_push_rdf(tsig_rr, algorithm_rdf);
        ldns_rr_push_rdf(tsig_rr, time_signed_rdf);
        ldns_rr_push_rdf(tsig_rr, fudge_rdf);
        ldns_rr_push_rdf(tsig_rr, mac_rdf);
        ldns_rr_push_rdf(tsig_rr, orig_id_rdf);
        ldns_rr_push_rdf(tsig_rr, error_rdf);
        ldns_rr_push_rdf(tsig_rr, other_data_rdf);
 
        ldns_pkt_set_tsig(pkt, tsig_rr);
 
        return status;
 
  clean:
        LDNS_FREE(pkt_wire);
        ldns_rdf_free(key_name_rdf);
        ldns_rdf_free(algorithm_rdf);
        ldns_rdf_free(time_signed_rdf);
        ldns_rdf_free(fudge_rdf);
        ldns_rdf_free(orig_id_rdf);
        ldns_rdf_free(error_rdf);
        ldns_rdf_free(other_data_rdf);
        return status;
}
#endif /* HAVE_SSL */