static void
sig_fuzz(struct sshkey *k, const char *sig_alg)
{
struct fuzz *fuzz;
u_char *sig, c[] = "some junk to be signed";
size_t l;
u_int fuzzers = FUZZ_1_BIT_FLIP | FUZZ_1_BYTE_FLIP | FUZZ_2_BYTE_FLIP |
FUZZ_TRUNCATE_START | FUZZ_TRUNCATE_END;
if (test_is_fast())
fuzzers &= ~FUZZ_2_BYTE_FLIP;
if (test_is_slow())
fuzzers |= FUZZ_2_BIT_FLIP;
ASSERT_INT_EQ(sshkey_sign(k, &sig, &l, c, sizeof(c), sig_alg, 0), 0);
ASSERT_SIZE_T_GT(l, 0);
fuzz = fuzz_begin(fuzzers, sig, l);
ASSERT_INT_EQ(sshkey_verify(k, sig, l, c, sizeof(c), NULL, 0), 0);
free(sig);
TEST_ONERROR(onerror, fuzz);
for(; !fuzz_done(fuzz); fuzz_next(fuzz)) {
/* Ensure 1-bit difference at least */
if (fuzz_matches_original(fuzz))
continue;
ASSERT_INT_NE(sshkey_verify(k, fuzz_ptr(fuzz), fuzz_len(fuzz),
c, sizeof(c), NULL, 0), 0);
}
fuzz_cleanup(fuzz);
}
static void
signature_test(struct sshkey *k, struct sshkey *bad, const u_char *d, size_t l)
{
size_t len;
u_char *sig;
ASSERT_INT_EQ(sshkey_sign(k, &sig, &len, d, l, 0), 0);
ASSERT_SIZE_T_GT(len, 8);
ASSERT_PTR_NE(sig, NULL);
ASSERT_INT_EQ(sshkey_verify(k, sig, len, d, l, 0), 0);
ASSERT_INT_NE(sshkey_verify(bad, sig, len, d, l, 0), 0);
/* Fuzz test is more comprehensive, this is just a smoke test */
sig[len - 5] ^= 0x10;
ASSERT_INT_NE(sshkey_verify(k, sig, len, d, l, 0), 0);
free(sig);
}
static void
sig_fuzz(struct sshkey *k)
{
struct fuzz *fuzz;
u_char *sig, c[] = "some junk to be signed";
size_t l;
ASSERT_INT_EQ(sshkey_sign(k, &sig, &l, c, sizeof(c), 0), 0);
ASSERT_SIZE_T_GT(l, 0);
fuzz = fuzz_begin(FUZZ_1_BIT_FLIP | /* too slow FUZZ_2_BIT_FLIP | */
FUZZ_1_BYTE_FLIP | FUZZ_2_BYTE_FLIP |
FUZZ_TRUNCATE_START | FUZZ_TRUNCATE_END, sig, l);
ASSERT_INT_EQ(sshkey_verify(k, sig, l, c, sizeof(c), 0), 0);
free(sig);
TEST_ONERROR(onerror, fuzz);
for(; !fuzz_done(fuzz); fuzz_next(fuzz)) {
sshkey_verify(k, fuzz_ptr(fuzz), fuzz_len(fuzz),
c, sizeof(c), 0);
}
fuzz_cleanup(fuzz);
}
int
key_verify(const Key *key, const u_char *signature, u_int signaturelen,
const u_char *data, u_int datalen)
{
int r;
if ((r = sshkey_verify(key, signature, signaturelen,
data, datalen, datafellows)) != 0) {
fatal_on_fatal_errors(r, __func__, 0);
error("%s: %s", __func__, ssh_err(r));
return r == SSH_ERR_SIGNATURE_INVALID ? 0 : -1;
}
return 1;
}
static int
input_kex_dh_gex_reply(int type, u_int32_t seq, struct ssh *ssh)
{
Kex *kex = ssh->kex;
BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
struct sshkey *server_host_key;
u_char *kbuf = NULL, *hash, *signature = NULL, *server_host_key_blob = NULL;
size_t klen = 0, slen, sbloblen, hashlen;
int kout, r;
debug("got SSH2_MSG_KEX_DH_GEX_REPLY");
if (kex->verify_host_key == NULL) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
/* key, cert */
if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
&sbloblen)) != 0 ||
(r = sshkey_from_blob(server_host_key_blob, sbloblen,
&server_host_key)) != 0)
goto out;
if (server_host_key->type != kex->hostkey_type) {
r = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (kex->verify_host_key(server_host_key, ssh) == -1) {
r = SSH_ERR_SIGNATURE_INVALID;
goto out;
}
/* DH parameter f, server public DH key */
if ((dh_server_pub = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
/* signed H */
if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 ||
(r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_server_pub= ");
BN_print_fp(stderr, dh_server_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_server_pub));
#endif
if (!dh_pub_is_valid(kex->dh, dh_server_pub)) {
sshpkt_disconnect(ssh, "bad server public DH value");
r = SSH_ERR_MESSAGE_INCOMPLETE;
goto out;
}
klen = DH_size(kex->dh);
if ((kbuf = malloc(klen)) == NULL ||
(shared_secret = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((kout = DH_compute_key(kbuf, dh_server_pub, kex->dh)) < 0 ||
BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if (ssh->compat & SSH_OLD_DHGEX)
kex->min = kex->max = -1;
/* calc and verify H */
if ((r = kexgex_hash(
kex->evp_md,
kex->client_version_string,
kex->server_version_string,
sshbuf_ptr(kex->my), sshbuf_len(kex->my),
sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
server_host_key_blob, sbloblen,
kex->min, kex->nbits, kex->max,
kex->dh->p, kex->dh->g,
kex->dh->pub_key,
dh_server_pub,
shared_secret,
&hash, &hashlen)) != 0)
goto out;
if ((r = sshkey_verify(server_host_key, signature, slen, hash,
hashlen, ssh->compat)) != 0)
goto out;
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = malloc(kex->session_id_len);
if (kex->session_id == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(kex->session_id, hash, kex->session_id_len);
}
if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
DH_free(kex->dh);
kex->dh = NULL;
if (server_host_key_blob)
free(server_host_key_blob);
if (server_host_key)
sshkey_free(server_host_key);
if (dh_server_pub)
BN_clear_free(dh_server_pub);
if (kbuf) {
bzero(kbuf, klen);
free(kbuf);
}
if (shared_secret)
BN_clear_free(shared_secret);
if (signature)
free(signature);
return r;
}
static int
input_kex_ecdh_reply(int type, u_int32_t seq, void *ctxt)
{
struct ssh *ssh = ctxt;
struct kex *kex = ssh->kex;
const EC_GROUP *group;
EC_POINT *server_public = NULL;
EC_KEY *client_key;
BIGNUM *shared_secret = NULL;
struct sshkey *server_host_key = NULL;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *kbuf = NULL;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t slen, sbloblen;
size_t klen = 0, hashlen;
int r;
if (kex->verify_host_key == NULL) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
group = kex->ec_group;
client_key = kex->ec_client_key;
/* hostkey */
if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
&sbloblen)) != 0 ||
(r = sshkey_from_blob(server_host_key_blob, sbloblen,
&server_host_key)) != 0)
goto out;
if (server_host_key->type != kex->hostkey_type ||
(kex->hostkey_type == KEY_ECDSA &&
server_host_key->ecdsa_nid != kex->hostkey_nid)) {
r = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (kex->verify_host_key(server_host_key, ssh) == -1) {
r = SSH_ERR_SIGNATURE_INVALID;
goto out;
}
/* Q_S, server public key */
/* signed H */
if ((server_public = EC_POINT_new(group)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = sshpkt_get_ec(ssh, server_public, group)) != 0 ||
(r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
#ifdef DEBUG_KEXECDH
fputs("server public key:\n", stderr);
sshkey_dump_ec_point(group, server_public);
#endif
if (sshkey_ec_validate_public(group, server_public) != 0) {
sshpkt_disconnect(ssh, "invalid server public key");
r = SSH_ERR_MESSAGE_INCOMPLETE;
goto out;
}
klen = (EC_GROUP_get_degree(group) + 7) / 8;
if ((kbuf = malloc(klen)) == NULL ||
(shared_secret = BN_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if (ECDH_compute_key(kbuf, klen, server_public,
client_key, NULL) != (int)klen ||
BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
#ifdef DEBUG_KEXECDH
dump_digest("shared secret", kbuf, klen);
#endif
/* calc and verify H */
hashlen = sizeof(hash);
if ((r = kex_ecdh_hash(
kex->hash_alg,
group,
kex->client_version_string,
kex->server_version_string,
sshbuf_ptr(kex->my), sshbuf_len(kex->my),
sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
server_host_key_blob, sbloblen,
EC_KEY_get0_public_key(client_key),
server_public,
shared_secret,
hash, &hashlen)) != 0)
goto out;
if ((r = sshkey_verify(server_host_key, signature, slen, hash,
hashlen, ssh->compat)) != 0)
goto out;
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = malloc(kex->session_id_len);
if (kex->session_id == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(kex->session_id, hash, kex->session_id_len);
}
if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
explicit_bzero(hash, sizeof(hash));
if (kex->ec_client_key) {
EC_KEY_free(kex->ec_client_key);
kex->ec_client_key = NULL;
}
if (server_public)
EC_POINT_clear_free(server_public);
if (kbuf) {
explicit_bzero(kbuf, klen);
free(kbuf);
}
if (shared_secret)
BN_clear_free(shared_secret);
sshkey_free(server_host_key);
free(server_host_key_blob);
free(signature);
return r;
}
static int
input_kex_c25519_reply(int type, u_int32_t seq, struct ssh *ssh)
{
struct kex *kex = ssh->kex;
struct sshkey *server_host_key = NULL;
struct sshbuf *shared_secret = NULL;
u_char *server_pubkey = NULL;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *hash;
size_t slen, pklen, sbloblen, hashlen;
int r;
if (kex->verify_host_key == NULL) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
/* hostkey */
if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
&sbloblen)) != 0 ||
(r = sshkey_from_blob(server_host_key_blob, sbloblen,
&server_host_key)) != 0)
goto out;
if (server_host_key->type != kex->hostkey_type) {
r = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (kex->verify_host_key(server_host_key, ssh) == -1) {
r = SSH_ERR_SIGNATURE_INVALID;
goto out;
}
/* Q_S, server public key */
/* signed H */
if ((r = sshpkt_get_string(ssh, &server_pubkey, &pklen)) != 0 ||
(r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
goto out;
if (pklen != CURVE25519_SIZE) {
r = SSH_ERR_SIGNATURE_INVALID;
goto out;
}
#ifdef DEBUG_KEXECDH
dump_digest("server public key:", server_pubkey, CURVE25519_SIZE);
#endif
if ((shared_secret = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = kexc25519_shared_key(kex->c25519_client_key, server_pubkey,
shared_secret)) < 0)
goto out;
/* calc and verify H */
if ((r = kex_c25519_hash(
kex->hash_alg,
kex->client_version_string,
kex->server_version_string,
sshbuf_ptr(kex->my), sshbuf_len(kex->my),
sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
server_host_key_blob, sbloblen,
kex->c25519_client_pubkey,
server_pubkey,
sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
&hash, &hashlen)) < 0)
goto out;
if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
ssh->compat)) != 0)
goto out;
/* save session id */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = malloc(kex->session_id_len);
if (kex->session_id == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(kex->session_id, hash, kex->session_id_len);
}
if ((r = kex_derive_keys(ssh, hash, hashlen, sshbuf_ptr(shared_secret),
sshbuf_len(shared_secret))) == 0)
r = kex_send_newkeys(ssh);
r = 0;
out:
explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key));
free(server_host_key_blob);
free(server_pubkey);
free(signature);
sshkey_free(server_host_key);
sshbuf_free(shared_secret);
return r;
}
static int
userauth_hostbased(struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
struct sshbuf *b;
struct sshkey *key = NULL;
char *pkalg, *cuser, *chost;
u_char *pkblob, *sig;
size_t alen, blen, slen;
int r, pktype, authenticated = 0;
if (!authctxt->valid) {
debug2("%s: disabled because of invalid user", __func__);
return 0;
}
/* XXX use sshkey_froms() */
if ((r = sshpkt_get_cstring(ssh, &pkalg, &alen)) != 0 ||
(r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
(r = sshpkt_get_cstring(ssh, &chost, NULL)) != 0 ||
(r = sshpkt_get_cstring(ssh, &cuser, NULL)) != 0 ||
(r = sshpkt_get_string(ssh, &sig, &slen)) != 0)
fatal("%s: packet parsing: %s", __func__, ssh_err(r));
debug("%s: cuser %s chost %s pkalg %s slen %zu", __func__,
cuser, chost, pkalg, slen);
#ifdef DEBUG_PK
debug("signature:");
sshbuf_dump_data(sig, siglen, stderr);
#endif
pktype = sshkey_type_from_name(pkalg);
if (pktype == KEY_UNSPEC) {
/* this is perfectly legal */
logit("%s: unsupported public key algorithm: %s",
__func__, pkalg);
goto done;
}
if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
error("%s: key_from_blob: %s", __func__, ssh_err(r));
goto done;
}
if (key == NULL) {
error("%s: cannot decode key: %s", __func__, pkalg);
goto done;
}
if (key->type != pktype) {
error("%s: type mismatch for decoded key "
"(received %d, expected %d)", __func__, key->type, pktype);
goto done;
}
if (sshkey_type_plain(key->type) == KEY_RSA &&
(ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
error("Refusing RSA key because peer uses unsafe "
"signature format");
goto done;
}
if (match_pattern_list(sshkey_ssh_name(key),
options.hostbased_key_types, 0) != 1) {
logit("%s: key type %s not in HostbasedAcceptedKeyTypes",
__func__, sshkey_type(key));
goto done;
}
if ((b = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
/* reconstruct packet */
if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
(r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->user)) != 0 ||
(r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
(r = sshbuf_put_cstring(b, "hostbased")) != 0 ||
(r = sshbuf_put_string(b, pkalg, alen)) != 0 ||
(r = sshbuf_put_string(b, pkblob, blen)) != 0 ||
(r = sshbuf_put_cstring(b, chost)) != 0 ||
(r = sshbuf_put_cstring(b, cuser)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
#ifdef DEBUG_PK
sshbuf_dump(b, stderr);
#endif
auth2_record_info(authctxt,
"client user \"%.100s\", client host \"%.100s\"", cuser, chost);
/* test for allowed key and correct signature */
authenticated = 0;
if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
PRIVSEP(sshkey_verify(key, sig, slen,
sshbuf_ptr(b), sshbuf_len(b), pkalg, ssh->compat)) == 0)
authenticated = 1;
auth2_record_key(authctxt, authenticated, key);
sshbuf_free(b);
done:
debug2("%s: authenticated %d", __func__, authenticated);
sshkey_free(key);
free(pkalg);
free(pkblob);
free(cuser);
free(chost);
free(sig);
return authenticated;
}
int
mm_answer_keyverify(int sock, struct sshbuf *m)
{
struct sshkey *key;
u_char *signature, *data, *blob;
size_t signaturelen, datalen, bloblen;
int r, ret, valid_data = 0;
if ((r = sshbuf_get_string(m, &blob, &bloblen)) != 0 ||
(r = sshbuf_get_string(m, &signature, &signaturelen)) != 0 ||
(r = sshbuf_get_string(m, &data, &datalen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (hostbased_cuser == NULL || hostbased_chost == NULL ||
!monitor_allowed_key(blob, bloblen))
fatal("%s: bad key, not previously allowed", __func__);
if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
fatal("%s: bad public key blob: %s", __func__, ssh_err(r));
switch (key_blobtype) {
case MM_USERKEY:
valid_data = monitor_valid_userblob(data, datalen);
break;
case MM_HOSTKEY:
valid_data = monitor_valid_hostbasedblob(data, datalen,
hostbased_cuser, hostbased_chost);
break;
default:
valid_data = 0;
break;
}
if (!valid_data)
fatal("%s: bad signature data blob", __func__);
ret = sshkey_verify(key, signature, signaturelen, data, datalen,
active_state->compat);
debug3("%s: key %p signature %s",
__func__, key, (r == 0) ? "verified" : "unverified");
/* If auth was successful then record key to ensure it isn't reused */
if (ret == 0)
auth2_record_userkey(authctxt, key);
else
sshkey_free(key);
free(blob);
free(signature);
free(data);
auth_method = key_blobtype == MM_USERKEY ? "publickey" : "hostbased";
monitor_reset_key_state();
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, ret)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
return ret == 0;
}
int
mm_answer_keyverify(int sock, struct sshbuf *m)
{
struct sshkey *key;
u_char *signature, *data, *blob;
size_t signaturelen, datalen, bloblen;
int r, ret, valid_data = 0, encoded_ret;
if ((r = sshbuf_get_string(m, &blob, &bloblen)) != 0 ||
(r = sshbuf_get_string(m, &signature, &signaturelen)) != 0 ||
(r = sshbuf_get_string(m, &data, &datalen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (hostbased_cuser == NULL || hostbased_chost == NULL ||
!monitor_allowed_key(blob, bloblen))
fatal("%s: bad key, not previously allowed", __func__);
/* XXX use sshkey_froms here; need to change key_blob, etc. */
if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
fatal("%s: bad public key blob: %s", __func__, ssh_err(r));
switch (key_blobtype) {
case MM_USERKEY:
valid_data = monitor_valid_userblob(data, datalen);
auth_method = "publickey";
break;
case MM_HOSTKEY:
valid_data = monitor_valid_hostbasedblob(data, datalen,
hostbased_cuser, hostbased_chost);
auth_method = "hostbased";
break;
default:
valid_data = 0;
break;
}
if (!valid_data)
fatal("%s: bad signature data blob", __func__);
ret = sshkey_verify(key, signature, signaturelen, data, datalen,
active_state->compat);
debug3("%s: %s %p signature %s", __func__, auth_method, key,
(ret == 0) ? "verified" : "unverified");
auth2_record_key(authctxt, ret == 0, key);
free(blob);
free(signature);
free(data);
monitor_reset_key_state();
sshkey_free(key);
sshbuf_reset(m);
/* encode ret != 0 as positive integer, since we're sending u32 */
encoded_ret = (ret != 0);
if ((r = sshbuf_put_u32(m, encoded_ret)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
return ret == 0;
}
