15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering

15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering

07630cea1f3a845c09309f197ac7c4f11edd3b62Lennart Poettering#include <gcrypt.h>

15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering

07630cea1f3a845c09309f197ac7c4f11edd3b62Lennart Poettering#include "alloc-util.h"

15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering#include "dns-domain.h"

15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering#include "hexdecoct.h"

15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering#include "resolved-dns-dnssec.h"

15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering#include "resolved-dns-packet.h"

15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering#include "string-table.h"

15bd9a285858c374684e75709de82681ab7daaa7Lennart Poettering

#define VERIFY_RRS_MAX 256

#define MAX_KEY_SIZE (32*1024)

#define SKEW_MAX (1*USEC_PER_HOUR + 10*USEC_PER_MINUTE)

#define NSEC3_ITERATIONS_MAX 2500

static void initialize_libgcrypt(void) {

const char *p;

if (gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P))

return;

p = gcry_check_version("1.4.5");

assert(p);

gcry_control(GCRYCTL_DISABLE_SECMEM);

gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);

}

uint16_t dnssec_keytag(DnsResourceRecord *dnskey, bool mask_revoke) {

const uint8_t *p;

uint32_t sum, f;

size_t i;

/* The algorithm from RFC 4034, Appendix B. */

assert(dnskey);

assert(dnskey->key->type == DNS_TYPE_DNSKEY);

f = (uint32_t) dnskey->dnskey.flags;

if (mask_revoke)

f &= ~DNSKEY_FLAG_REVOKE;

sum = f + ((((uint32_t) dnskey->dnskey.protocol) << 8) + (uint32_t) dnskey->dnskey.algorithm);

p = dnskey->dnskey.key;

for (i = 0; i < dnskey->dnskey.key_size; i++)

sum += (i & 1) == 0 ? (uint32_t) p[i] << 8 : (uint32_t) p[i];

sum += (sum >> 16) & UINT32_C(0xFFFF);

return sum & UINT32_C(0xFFFF);

}

static int rr_compare(const void *a, const void *b) {

DnsResourceRecord **x = (DnsResourceRecord**) a, **y = (DnsResourceRecord**) b;

size_t m;

int r;

/* Let's order the RRs according to RFC 4034, Section 6.3 */

assert(x);

assert(*x);

assert((*x)->wire_format);

assert(y);

assert(*y);

assert((*y)->wire_format);

m = MIN(DNS_RESOURCE_RECORD_RDATA_SIZE(*x), DNS_RESOURCE_RECORD_RDATA_SIZE(*y));

r = memcmp(DNS_RESOURCE_RECORD_RDATA(*x), DNS_RESOURCE_RECORD_RDATA(*y), m);

if (r != 0)

return r;

if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) < DNS_RESOURCE_RECORD_RDATA_SIZE(*y))

return -1;

else if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) > DNS_RESOURCE_RECORD_RDATA_SIZE(*y))

return 1;

return 0;

}

static int dnssec_rsa_verify_raw(

const char *hash_algorithm,

const void *signature, size_t signature_size,

const void *data, size_t data_size,

const void *exponent, size_t exponent_size,

const void *modulus, size_t modulus_size) {

gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL;

gcry_mpi_t n = NULL, e = NULL, s = NULL;

gcry_error_t ge;

int r;

assert(hash_algorithm);

ge = gcry_mpi_scan(&s, GCRYMPI_FMT_USG, signature, signature_size, NULL);

if (ge != 0) {

r = -EIO;

goto finish;

}

ge = gcry_mpi_scan(&e, GCRYMPI_FMT_USG, exponent, exponent_size, NULL);

if (ge != 0) {

r = -EIO;

goto finish;

}

ge = gcry_mpi_scan(&n, GCRYMPI_FMT_USG, modulus, modulus_size, NULL);

if (ge != 0) {

r = -EIO;

goto finish;

}

ge = gcry_sexp_build(&signature_sexp,

NULL,

"(sig-val (rsa (s %m)))",

s);

if (ge != 0) {

r = -EIO;

goto finish;

}

ge = gcry_sexp_build(&data_sexp,

NULL,

"(data (flags pkcs1) (hash %s %b))",

hash_algorithm,

(int) data_size,

data);

if (ge != 0) {

r = -EIO;

goto finish;

}

ge = gcry_sexp_build(&public_key_sexp,

NULL,

"(public-key (rsa (n %m) (e %m)))",

n,

e);

if (ge != 0) {

r = -EIO;

goto finish;

}

ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp);

if (gpg_err_code(ge) == GPG_ERR_BAD_SIGNATURE)

r = 0;

else if (ge != 0) {

log_debug("RSA signature check failed: %s", gpg_strerror(ge));

r = -EIO;

} else

r = 1;

finish:

if (e)

gcry_mpi_release(e);

if (n)

gcry_mpi_release(n);

if (s)

gcry_mpi_release(s);

if (public_key_sexp)

gcry_sexp_release(public_key_sexp);

if (signature_sexp)

gcry_sexp_release(signature_sexp);

if (data_sexp)

gcry_sexp_release(data_sexp);

return r;

}

static int dnssec_rsa_verify(

const char *hash_algorithm,

const void *hash, size_t hash_size,

DnsResourceRecord *rrsig,

DnsResourceRecord *dnskey) {

size_t exponent_size, modulus_size;

void *exponent, *modulus;

assert(hash_algorithm);

assert(hash);

assert(hash_size > 0);

assert(rrsig);

assert(dnskey);

if (*(uint8_t*) dnskey->dnskey.key == 0) {

/* exponent is > 255 bytes long */

exponent = (uint8_t*) dnskey->dnskey.key + 3;

exponent_size =

((size_t) (((uint8_t*) dnskey->dnskey.key)[1]) << 8) |

((size_t) ((uint8_t*) dnskey->dnskey.key)[2]);

if (exponent_size < 256)

return -EINVAL;

if (3 + exponent_size >= dnskey->dnskey.key_size)

return -EINVAL;

modulus = (uint8_t*) dnskey->dnskey.key + 3 + exponent_size;

modulus_size = dnskey->dnskey.key_size - 3 - exponent_size;

} else {

/* exponent is <= 255 bytes long */

exponent = (uint8_t*) dnskey->dnskey.key + 1;

exponent_size = (size_t) ((uint8_t*) dnskey->dnskey.key)[0];

if (exponent_size <= 0)

return -EINVAL;

if (1 + exponent_size >= dnskey->dnskey.key_size)

return -EINVAL;

modulus = (uint8_t*) dnskey->dnskey.key + 1 + exponent_size;

modulus_size = dnskey->dnskey.key_size - 1 - exponent_size;

}

return dnssec_rsa_verify_raw(

hash_algorithm,

rrsig->rrsig.signature, rrsig->rrsig.signature_size,

hash, hash_size,

exponent, exponent_size,

modulus, modulus_size);

}

static int dnssec_ecdsa_verify_raw(

const char *hash_algorithm,

const char *curve,

const void *signature_r, size_t signature_r_size,

const void *signature_s, size_t signature_s_size,

const void *data, size_t data_size,

const void *key, size_t key_size) {

gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL;

gcry_mpi_t q = NULL, r = NULL, s = NULL;

gcry_error_t ge;

int k;

assert(hash_algorithm);

ge = gcry_mpi_scan(&r, GCRYMPI_FMT_USG, signature_r, signature_r_size, NULL);

if (ge != 0) {

k = -EIO;

goto finish;

}

ge = gcry_mpi_scan(&s, GCRYMPI_FMT_USG, signature_s, signature_s_size, NULL);

if (ge != 0) {

k = -EIO;

goto finish;

}

ge = gcry_mpi_scan(&q, GCRYMPI_FMT_USG, key, key_size, NULL);

if (ge != 0) {

k = -EIO;

goto finish;

}

ge = gcry_sexp_build(&signature_sexp,

NULL,

"(sig-val (ecdsa (r %m) (s %m)))",

r,

s);

if (ge != 0) {

k = -EIO;

goto finish;

}

ge = gcry_sexp_build(&data_sexp,

NULL,

"(data (flags rfc6979) (hash %s %b))",

hash_algorithm,

(int) data_size,

data);

if (ge != 0) {

k = -EIO;

goto finish;

}

ge = gcry_sexp_build(&public_key_sexp,

NULL,

"(public-key (ecc (curve %s) (q %m)))",

curve,

q);

if (ge != 0) {

k = -EIO;

goto finish;

}

ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp);

if (gpg_err_code(ge) == GPG_ERR_BAD_SIGNATURE)

k = 0;

else if (ge != 0) {

log_debug("ECDSA signature check failed: %s", gpg_strerror(ge));

k = -EIO;

} else

k = 1;

finish:

if (r)

gcry_mpi_release(r);

if (s)

gcry_mpi_release(s);

if (q)

gcry_mpi_release(q);

if (public_key_sexp)

gcry_sexp_release(public_key_sexp);

if (signature_sexp)

gcry_sexp_release(signature_sexp);

if (data_sexp)

gcry_sexp_release(data_sexp);

return k;

}

static int dnssec_ecdsa_verify(

const char *hash_algorithm,

int algorithm,

const void *hash, size_t hash_size,

DnsResourceRecord *rrsig,

DnsResourceRecord *dnskey) {

const char *curve;

size_t key_size;

uint8_t *q;

assert(hash);

assert(hash_size);

assert(rrsig);

assert(dnskey);

if (algorithm == DNSSEC_ALGORITHM_ECDSAP256SHA256) {

key_size = 32;

curve = "NIST P-256";

} else if (algorithm == DNSSEC_ALGORITHM_ECDSAP384SHA384) {

key_size = 48;

curve = "NIST P-384";

} else

return -EOPNOTSUPP;

if (dnskey->dnskey.key_size != key_size * 2)

return -EINVAL;

if (rrsig->rrsig.signature_size != key_size * 2)

return -EINVAL;

q = alloca(key_size*2 + 1);

q[0] = 0x04; /* Prepend 0x04 to indicate an uncompressed key */

memcpy(q+1, dnskey->dnskey.key, key_size*2);

return dnssec_ecdsa_verify_raw(

hash_algorithm,

curve,

rrsig->rrsig.signature, key_size,

(uint8_t*) rrsig->rrsig.signature + key_size, key_size,

hash, hash_size,

q, key_size*2+1);

}

static void md_add_uint8(gcry_md_hd_t md, uint8_t v) {

gcry_md_write(md, &v, sizeof(v));

}

static void md_add_uint16(gcry_md_hd_t md, uint16_t v) {

v = htobe16(v);

gcry_md_write(md, &v, sizeof(v));

}

static void md_add_uint32(gcry_md_hd_t md, uint32_t v) {

v = htobe32(v);

gcry_md_write(md, &v, sizeof(v));

}

static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) {

usec_t expiration, inception, skew;

assert(rrsig);

assert(rrsig->key->type == DNS_TYPE_RRSIG);

if (realtime == USEC_INFINITY)

realtime = now(CLOCK_REALTIME);

expiration = rrsig->rrsig.expiration * USEC_PER_SEC;

inception = rrsig->rrsig.inception * USEC_PER_SEC;

if (inception > expiration)

return -EKEYREJECTED;

/* Permit a certain amount of clock skew of 10% of the valid

skew = (expiration - inception) / 10;

if (skew > SKEW_MAX)

skew = SKEW_MAX;

if (inception < skew)

inception = 0;

else

inception -= skew;

if (expiration + skew < expiration)

expiration = USEC_INFINITY;

else

expiration += skew;

return realtime < inception || realtime > expiration;

}

static int algorithm_to_gcrypt_md(uint8_t algorithm) {

/* Translates a DNSSEC signature algorithm into a gcrypt

switch (algorithm) {

case DNSSEC_ALGORITHM_RSASHA1:

case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:

return GCRY_MD_SHA1;

case DNSSEC_ALGORITHM_RSASHA256:

case DNSSEC_ALGORITHM_ECDSAP256SHA256:

return GCRY_MD_SHA256;

case DNSSEC_ALGORITHM_ECDSAP384SHA384:

return GCRY_MD_SHA384;

case DNSSEC_ALGORITHM_RSASHA512:

return GCRY_MD_SHA512;

default:

return -EOPNOTSUPP;

}

}

int dnssec_verify_rrset(

DnsAnswer *a,

const DnsResourceKey *key,

DnsResourceRecord *rrsig,

DnsResourceRecord *dnskey,

usec_t realtime,

DnssecResult *result) {

uint8_t wire_format_name[DNS_WIRE_FOMAT_HOSTNAME_MAX];

size_t hash_size;

void *hash;

DnsResourceRecord **list, *rr;

gcry_md_hd_t md = NULL;

int r, md_algorithm;

size_t k, n = 0;

assert(key);

assert(rrsig);

assert(dnskey);

assert(result);

assert(rrsig->key->type == DNS_TYPE_RRSIG);

assert(dnskey->key->type == DNS_TYPE_DNSKEY);

/* Verifies the the RRSet matching the specified "key" in "a",

md_algorithm = algorithm_to_gcrypt_md(rrsig->rrsig.algorithm);

if (md_algorithm == -EOPNOTSUPP) {

*result = DNSSEC_UNSUPPORTED_ALGORITHM;

return 0;

}

if (md_algorithm < 0)

return md_algorithm;

r = dnssec_rrsig_expired(rrsig, realtime);

if (r < 0)

return r;

if (r > 0) {

*result = DNSSEC_SIGNATURE_EXPIRED;

return 0;

}

/* Collect all relevant RRs in a single array, so that we can look at the RRset */

list = newa(DnsResourceRecord *, dns_answer_size(a));

DNS_ANSWER_FOREACH(rr, a) {

r = dns_resource_key_equal(key, rr->key);

if (r < 0)

return r;

if (r == 0)

continue;

/* We need the wire format for ordering, and digest calculation */

r = dns_resource_record_to_wire_format(rr, true);

if (r < 0)

return r;

list[n++] = rr;

if (n > VERIFY_RRS_MAX)

return -E2BIG;

}

if (n <= 0)

return -ENODATA;

/* Bring the RRs into canonical order */

qsort_safe(list, n, sizeof(DnsResourceRecord*), rr_compare);

/* OK, the RRs are now in canonical order. Let's calculate the digest */

initialize_libgcrypt();

hash_size = gcry_md_get_algo_dlen(md_algorithm);

assert(hash_size > 0);

gcry_md_open(&md, md_algorithm, 0);

if (!md)

return -EIO;

md_add_uint16(md, rrsig->rrsig.type_covered);

md_add_uint8(md, rrsig->rrsig.algorithm);

md_add_uint8(md, rrsig->rrsig.labels);

md_add_uint32(md, rrsig->rrsig.original_ttl);

md_add_uint32(md, rrsig->rrsig.expiration);

md_add_uint32(md, rrsig->rrsig.inception);

md_add_uint16(md, rrsig->rrsig.key_tag);

r = dns_name_to_wire_format(rrsig->rrsig.signer, wire_format_name, sizeof(wire_format_name), true);

if (r < 0)

goto finish;

gcry_md_write(md, wire_format_name, r);

for (k = 0; k < n; k++) {

const char *suffix;

size_t l;

rr = list[k];

r = dns_name_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rrsig->rrsig.labels, &suffix);

if (r < 0)

goto finish;

if (r > 0) /* This is a wildcard! */

gcry_md_write(md, (uint8_t[]) { 1, '*'}, 2);

r = dns_name_to_wire_format(suffix, wire_format_name, sizeof(wire_format_name), true);

if (r < 0)

goto finish;

gcry_md_write(md, wire_format_name, r);

md_add_uint16(md, rr->key->type);

md_add_uint16(md, rr->key->class);

md_add_uint32(md, rrsig->rrsig.original_ttl);

l = DNS_RESOURCE_RECORD_RDATA_SIZE(rr);

assert(l <= 0xFFFF);

md_add_uint16(md, (uint16_t) l);

gcry_md_write(md, DNS_RESOURCE_RECORD_RDATA(rr), l);

}

hash = gcry_md_read(md, 0);

if (!hash) {

r = -EIO;

goto finish;

}

switch (rrsig->rrsig.algorithm) {

case DNSSEC_ALGORITHM_RSASHA1:

case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:

case DNSSEC_ALGORITHM_RSASHA256:

case DNSSEC_ALGORITHM_RSASHA512:

r = dnssec_rsa_verify(

gcry_md_algo_name(md_algorithm),

hash, hash_size,

rrsig,

dnskey);

break;

case DNSSEC_ALGORITHM_ECDSAP256SHA256:

case DNSSEC_ALGORITHM_ECDSAP384SHA384:

r = dnssec_ecdsa_verify(

gcry_md_algo_name(md_algorithm),

rrsig->rrsig.algorithm,

hash, hash_size,

rrsig,

dnskey);

break;

}

if (r < 0)

goto finish;

*result = r ? DNSSEC_VALIDATED : DNSSEC_INVALID;

r = 0;

finish:

gcry_md_close(md);

return r;

}

int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey, bool revoked_ok) {

assert(rrsig);

assert(dnskey);

/* Checks if the specified DNSKEY RR matches the key used for

if (rrsig->key->type != DNS_TYPE_RRSIG)

return -EINVAL;

if (dnskey->key->type != DNS_TYPE_DNSKEY)

return 0;

if (dnskey->key->class != rrsig->key->class)

return 0;

if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)

return 0;

if (!revoked_ok && (dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE))

return 0;

if (dnskey->dnskey.protocol != 3)

return 0;

if (dnskey->dnskey.algorithm != rrsig->rrsig.algorithm)

return 0;

if (dnssec_keytag(dnskey, false) != rrsig->rrsig.key_tag)

return 0;

return dns_name_equal(DNS_RESOURCE_KEY_NAME(dnskey->key), rrsig->rrsig.signer);

}

int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) {

int r;

assert(key);

assert(rrsig);

/* Checks if the specified RRSIG RR protects the RRSet of the specified RR key. */

if (rrsig->key->type != DNS_TYPE_RRSIG)

return 0;

if (rrsig->key->class != key->class)

return 0;

if (rrsig->rrsig.type_covered != key->type)

return 0;

/* Make sure signer is a parent of the RRset */

r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(rrsig->key), rrsig->rrsig.signer);

if (r <= 0)

return r;

/* Make sure the owner name has at least as many labels as the "label" fields indicates. */

r = dns_name_count_labels(DNS_RESOURCE_KEY_NAME(rrsig->key));

if (r < 0)

return r;

if (r < rrsig->rrsig.labels)

return 0;

return dns_name_equal(DNS_RESOURCE_KEY_NAME(rrsig->key), DNS_RESOURCE_KEY_NAME(key));

}

static int dnssec_fix_rrset_ttl(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord *rrsig, usec_t realtime) {

DnsResourceRecord *rr;

int r;

assert(key);

assert(rrsig);

DNS_ANSWER_FOREACH(rr, a) {

r = dns_resource_key_equal(key, rr->key);

if (r < 0)

return r;

if (r == 0)

continue;

/* Pick the TTL as the minimum of the RR's TTL, the

rr->ttl = MIN3(rr->ttl, rrsig->rrsig.original_ttl, rrsig->ttl);

rr->expiry = rrsig->rrsig.expiration * USEC_PER_SEC;

}

return 0;

}

int dnssec_verify_rrset_search(

DnsAnswer *a,

const DnsResourceKey *key,

DnsAnswer *validated_dnskeys,

usec_t realtime,

DnssecResult *result) {

bool found_rrsig = false, found_invalid = false, found_expired_rrsig = false, found_unsupported_algorithm = false;

DnsResourceRecord *rrsig;

int r;

assert(key);

assert(result);

/* Verifies all RRs from "a" that match the key "key" against DNSKEYs in "validated_dnskeys" */

if (!a || a->n_rrs <= 0)

return -ENODATA;

/* Iterate through each RRSIG RR. */

DNS_ANSWER_FOREACH(rrsig, a) {

DnsResourceRecord *dnskey;

DnsAnswerFlags flags;

/* Is this an RRSIG RR that applies to RRs matching our key? */

r = dnssec_key_match_rrsig(key, rrsig);

if (r < 0)

return r;

if (r == 0)

continue;

found_rrsig = true;

/* Look for a matching key */

DNS_ANSWER_FOREACH_FLAGS(dnskey, flags, validated_dnskeys) {

DnssecResult one_result;

if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)

continue;

/* Is this a DNSKEY RR that matches they key of our RRSIG? */

r = dnssec_rrsig_match_dnskey(rrsig, dnskey, false);

if (r < 0)

return r;

if (r == 0)

continue;

/* Take the time here, if it isn't set yet, so

if (realtime == USEC_INFINITY)

realtime = now(CLOCK_REALTIME);

/* Yay, we found a matching RRSIG with a matching

r = dnssec_verify_rrset(a, key, rrsig, dnskey, realtime, &one_result);

if (r < 0)

return r;

switch (one_result) {

case DNSSEC_VALIDATED:

/* Yay, the RR has been validated,

r = dnssec_fix_rrset_ttl(a, key, rrsig, realtime);

if (r < 0)

return r;

*result = DNSSEC_VALIDATED;

return 0;

case DNSSEC_INVALID:

/* If the signature is invalid, let's try another

found_invalid = true;

continue;

case DNSSEC_UNSUPPORTED_ALGORITHM:

/* If the key algorithm is

found_unsupported_algorithm = true;

continue;

case DNSSEC_SIGNATURE_EXPIRED:

/* If the signature is expired, try

found_expired_rrsig = true;

continue;

default:

assert_not_reached("Unexpected DNSSEC validation result");

}

}

}

if (found_expired_rrsig)

*result = DNSSEC_SIGNATURE_EXPIRED;

else if (found_unsupported_algorithm)

*result = DNSSEC_UNSUPPORTED_ALGORITHM;

else if (found_invalid)

*result = DNSSEC_INVALID;

else if (found_rrsig)

*result = DNSSEC_MISSING_KEY;

else

*result = DNSSEC_NO_SIGNATURE;

return 0;

}

int dnssec_has_rrsig(DnsAnswer *a, const DnsResourceKey *key) {

DnsResourceRecord *rr;

int r;

/* Checks whether there's at least one RRSIG in 'a' that proctects RRs of the specified key */

DNS_ANSWER_FOREACH(rr, a) {

r = dnssec_key_match_rrsig(key, rr);

if (r < 0)

return r;

if (r > 0)

return 1;

}

return 0;

}

int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max) {

size_t c = 0;

int r;

/* Converts the specified hostname into DNSSEC canonicalized

if (buffer_max < 2)

return -ENOBUFS;

for (;;) {

r = dns_label_unescape(&n, buffer, buffer_max);

if (r < 0)

return r;

if (r == 0)

break;

if (r > 0) {

int k;

/* DNSSEC validation is always done on the ASCII version of the label */

k = dns_label_apply_idna(buffer, r, buffer, buffer_max);

if (k < 0)

return k;

if (k > 0)

r = k;

}

if (buffer_max < (size_t) r + 2)

return -ENOBUFS;

/* The DNSSEC canonical form is not clear on what to

if (memchr(buffer, '.', r))

return -EINVAL;

ascii_strlower_n(buffer, (size_t) r);

buffer[r] = '.';

buffer += r + 1;

c += r + 1;

buffer_max -= r + 1;

}

if (c <= 0) {

/* Not even a single label: this is the root domain name */

assert(buffer_max > 2);

buffer[0] = '.';

buffer[1] = 0;

return 1;

}

return (int) c;

}

static int digest_to_gcrypt_md(uint8_t algorithm) {

/* Translates a DNSSEC digest algorithm into a gcrypt digest identifier */

switch (algorithm) {

case DNSSEC_DIGEST_SHA1:

return GCRY_MD_SHA1;

case DNSSEC_DIGEST_SHA256:

return GCRY_MD_SHA256;

case DNSSEC_DIGEST_SHA384:

return GCRY_MD_SHA384;

default:

return -EOPNOTSUPP;

}

}

int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds, bool mask_revoke) {

char owner_name[DNSSEC_CANONICAL_HOSTNAME_MAX];

gcry_md_hd_t md = NULL;

size_t hash_size;

int md_algorithm, r;

void *result;

assert(dnskey);

assert(ds);

/* Implements DNSKEY verification by a DS, according to RFC 4035, section 5.2 */

if (dnskey->key->type != DNS_TYPE_DNSKEY)

return -EINVAL;

if (ds->key->type != DNS_TYPE_DS)

return -EINVAL;

if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)

return -EKEYREJECTED;

if (!mask_revoke && (dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE))

return -EKEYREJECTED;

if (dnskey->dnskey.protocol != 3)

return -EKEYREJECTED;

if (dnskey->dnskey.algorithm != ds->ds.algorithm)

return 0;

if (dnssec_keytag(dnskey, mask_revoke) != ds->ds.key_tag)

return 0;

initialize_libgcrypt();

md_algorithm = digest_to_gcrypt_md(ds->ds.digest_type);

if (md_algorithm < 0)

return md_algorithm;

hash_size = gcry_md_get_algo_dlen(md_algorithm);

assert(hash_size > 0);

if (ds->ds.digest_size != hash_size)

return 0;

r = dnssec_canonicalize(DNS_RESOURCE_KEY_NAME(dnskey->key), owner_name, sizeof(owner_name));

if (r < 0)

return r;

gcry_md_open(&md, md_algorithm, 0);

if (!md)

return -EIO;

gcry_md_write(md, owner_name, r);

if (mask_revoke)

md_add_uint16(md, dnskey->dnskey.flags & ~DNSKEY_FLAG_REVOKE);

else

md_add_uint16(md, dnskey->dnskey.flags);

md_add_uint8(md, dnskey->dnskey.protocol);

md_add_uint8(md, dnskey->dnskey.algorithm);

gcry_md_write(md, dnskey->dnskey.key, dnskey->dnskey.key_size);

result = gcry_md_read(md, 0);

if (!result) {

r = -EIO;

goto finish;

}

r = memcmp(result, ds->ds.digest, ds->ds.digest_size) != 0;

finish:

gcry_md_close(md);

return r;

}

int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) {

DnsResourceRecord *ds;

DnsAnswerFlags flags;

int r;

assert(dnskey);

if (dnskey->key->type != DNS_TYPE_DNSKEY)

return 0;

DNS_ANSWER_FOREACH_FLAGS(ds, flags, validated_ds) {

if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)

continue;

if (ds->key->type != DNS_TYPE_DS)

continue;

if (ds->key->class != dnskey->key->class)

continue;

r = dns_name_equal(DNS_RESOURCE_KEY_NAME(dnskey->key), DNS_RESOURCE_KEY_NAME(ds->key));

if (r < 0)

return r;

if (r == 0)

continue;

r = dnssec_verify_dnskey(dnskey, ds, false);

if (r == -EKEYREJECTED)

return 0; /* The DNSKEY is revoked or otherwise invalid, we won't bless it */

if (r < 0)

return r;

if (r > 0)

return 1;

}

return 0;

}

static int nsec3_hash_to_gcrypt_md(uint8_t algorithm) {

/* Translates a DNSSEC NSEC3 hash algorithm into a gcrypt digest identifier */

switch (algorithm) {

case NSEC3_ALGORITHM_SHA1:

return GCRY_MD_SHA1;

default:

return -EOPNOTSUPP;

}

}

int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret) {

uint8_t wire_format[DNS_WIRE_FOMAT_HOSTNAME_MAX];

gcry_md_hd_t md = NULL;

size_t hash_size;

int algorithm;

void *result;

unsigned k;

int r;

assert(nsec3);

assert(name);

assert(ret);

if (nsec3->key->type != DNS_TYPE_NSEC3)

return -EINVAL;

if (nsec3->nsec3.iterations > NSEC3_ITERATIONS_MAX) {

log_debug("Ignoring NSEC3 RR %s with excessive number of iterations.", dns_resource_record_to_string(nsec3));

return -EOPNOTSUPP;

}

algorithm = nsec3_hash_to_gcrypt_md(nsec3->nsec3.algorithm);

if (algorithm < 0)

return algorithm;

initialize_libgcrypt();

hash_size = gcry_md_get_algo_dlen(algorithm);

assert(hash_size > 0);

if (nsec3->nsec3.next_hashed_name_size != hash_size)

return -EINVAL;

r = dns_name_to_wire_format(name, wire_format, sizeof(wire_format), true);

if (r < 0)

return r;

gcry_md_open(&md, algorithm, 0);

if (!md)

return -EIO;

gcry_md_write(md, wire_format, r);

gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size);

result = gcry_md_read(md, 0);

if (!result) {

r = -EIO;

goto finish;

}

for (k = 0; k < nsec3->nsec3.iterations; k++) {

uint8_t tmp[hash_size];

memcpy(tmp, result, hash_size);

gcry_md_reset(md);

gcry_md_write(md, tmp, hash_size);

gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size);

result = gcry_md_read(md, 0);

if (!result) {

r = -EIO;

goto finish;

}

}

memcpy(ret, result, hash_size);

r = (int) hash_size;

finish:

gcry_md_close(md);

return r;

}

static int nsec3_is_good(DnsResourceRecord *rr, DnsResourceRecord *nsec3) {

const char *a, *b;

int r;

assert(rr);

if (rr->key->type != DNS_TYPE_NSEC3)

return 0;

/* RFC 5155, Section 8.2 says we MUST ignore NSEC3 RRs with flags != 0 or 1 */

if (!IN_SET(rr->nsec3.flags, 0, 1))

return 0;

/* Ignore NSEC3 RRs whose algorithm we don't know */

if (nsec3_hash_to_gcrypt_md(rr->nsec3.algorithm) < 0)

return 0;

/* Ignore NSEC3 RRs with an excessive number of required iterations */

if (rr->nsec3.iterations > NSEC3_ITERATIONS_MAX)

return 0;

if (!nsec3)

return 1;

/* If a second NSEC3 RR is specified, also check if they are from the same zone. */

if (nsec3 == rr) /* Shortcut */

return 1;

if (rr->key->class != nsec3->key->class)

return 0;

if (rr->nsec3.algorithm != nsec3->nsec3.algorithm)

return 0;

if (rr->nsec3.iterations != nsec3->nsec3.iterations)

return 0;

if (rr->nsec3.salt_size != nsec3->nsec3.salt_size)

return 0;

if (memcmp(rr->nsec3.salt, nsec3->nsec3.salt, rr->nsec3.salt_size) != 0)

return 0;

a = DNS_RESOURCE_KEY_NAME(rr->key);

r = dns_name_parent(&a); /* strip off hash */

if (r < 0)

return r;

if (r == 0)

return 0;

b = DNS_RESOURCE_KEY_NAME(nsec3->key);

r = dns_name_parent(&b); /* strip off hash */

if (r < 0)

return r;

if (r == 0)

return 0;

return dns_name_equal(a, b);

}

static int nsec3_hashed_domain(DnsResourceRecord *nsec3, const char *domain, const char *zone, char **ret) {

_cleanup_free_ char *l = NULL, *hashed_domain = NULL;

uint8_t hashed[DNSSEC_HASH_SIZE_MAX];

int hashed_size;

assert(nsec3);

assert(domain);

assert(zone);

assert(ret);

hashed_size = dnssec_nsec3_hash(nsec3, domain, hashed);

if (hashed_size < 0)

return hashed_size;

l = base32hexmem(hashed, hashed_size, false);

if (!l)

return -ENOMEM;

hashed_domain = strjoin(l, ".", zone, NULL);

if (!hashed_domain)

return -ENOMEM;

*ret = hashed_domain;

hashed_domain = NULL;

return hashed_size;

}

static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) {

_cleanup_free_ char *next_closer_domain = NULL, *wildcard = NULL, *wildcard_domain = NULL;

const char *zone, *p, *pp = NULL;

DnsResourceRecord *rr, *enclosure_rr, *zone_rr, *wildcard_rr = NULL;

DnsAnswerFlags flags;

int hashed_size, r;

bool a, no_closer = false, no_wildcard = false, optout = false;

assert(key);

assert(result);

/* First step, find the zone name and the NSEC3 parameters of the zone.

zone = DNS_RESOURCE_KEY_NAME(key);

for (;;) {

DNS_ANSWER_FOREACH_FLAGS(zone_rr, flags, answer) {

r = nsec3_is_good(zone_rr, NULL);

if (r < 0)

return r;

if (r == 0)

continue;

r = dns_name_equal_skip(DNS_RESOURCE_KEY_NAME(zone_rr->key), 1, zone);

if (r < 0)

return r;

if (r > 0)

goto found_zone;

}

/* Strip one label from the front */

r = dns_name_parent(&zone);

if (r < 0)

return r;

if (r == 0)

break;

}

*result = DNSSEC_NSEC_NO_RR;

return 0;

found_zone:

/* Second step, find the closest encloser NSEC3 RR in 'answer' that matches 'key' */

p = DNS_RESOURCE_KEY_NAME(key);

for (;;) {

_cleanup_free_ char *hashed_domain = NULL;

hashed_size = nsec3_hashed_domain(zone_rr, p, zone, &hashed_domain);

if (hashed_size == -EOPNOTSUPP) {

*result = DNSSEC_NSEC_UNSUPPORTED_ALGORITHM;

return 0;

}

if (hashed_size < 0)

return hashed_size;

DNS_ANSWER_FOREACH_FLAGS(enclosure_rr, flags, answer) {

r = nsec3_is_good(enclosure_rr, zone_rr);

if (r < 0)

return r;

if (r == 0)

continue;

if (enclosure_rr->nsec3.next_hashed_name_size != (size_t) hashed_size)

continue;

r = dns_name_equal(DNS_RESOURCE_KEY_NAME(enclosure_rr->key), hashed_domain);

if (r < 0)

return r;

if (r > 0) {

a = flags & DNS_ANSWER_AUTHENTICATED;

goto found_closest_encloser;

}

}

/* We didn't find the closest encloser with this name,

pp = p;

/* Strip one label from the front */

r = dns_name_parent(&p);

if (r < 0)

return r;

if (r == 0)

break;

}

*result = DNSSEC_NSEC_NO_RR;

return 0;

found_closest_encloser:

/* We found a closest encloser in 'p'; next closer is 'pp' */

/* Ensure this is not a DNAME domain, see RFC5155, section 8.3. */

if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_DNAME))

return -EBADMSG;

/* Ensure that this data is from the delegated domain

if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_NS) &&

!bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_SOA))

return -EBADMSG;

if (!pp) {

/* No next closer NSEC3 RR. That means there's a direct NSEC3 RR for our key. */

if (bitmap_isset(enclosure_rr->nsec3.types, key->type))

*result = DNSSEC_NSEC_FOUND;

else if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_CNAME))

*result = DNSSEC_NSEC_CNAME;

else

*result = DNSSEC_NSEC_NODATA;

if (authenticated)

*authenticated = a;

if (ttl)

*ttl = enclosure_rr->ttl;

return 0;

}