int
mm_key_verify(Key *key, u_char *sig, u_int siglen, u_char *data, u_int datalen)
{
Buffer m;
u_char *blob;
u_int len;
int verified = 0;
debug3("%s entering", __func__);
/* Convert the key to a blob and the pass it over */
if (!key_to_blob(key, &blob, &len))
return (0);
buffer_init(&m);
buffer_put_string(&m, blob, len);
buffer_put_string(&m, sig, siglen);
buffer_put_string(&m, data, datalen);
xfree(blob);
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYVERIFY, &m);
debug3("%s: waiting for MONITOR_ANS_KEYVERIFY", __func__);
mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_KEYVERIFY, &m);
verified = buffer_get_int(&m);
buffer_free(&m);
return (verified);
}
BIGNUM *
mm_auth_rsa_generate_challenge(Key *key)
{
Buffer m;
BIGNUM *challenge;
u_char *blob;
u_int blen;
debug3("%s entering", __func__);
if ((challenge = BN_new()) == NULL)
fatal("%s: BN_new failed", __func__);
key->type = KEY_RSA; /* XXX cheat for key_to_blob */
if (key_to_blob(key, &blob, &blen) == 0)
fatal("%s: key_to_blob failed", __func__);
key->type = KEY_RSA1;
buffer_init(&m);
buffer_put_string(&m, blob, blen);
xfree(blob);
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_RSACHALLENGE, &m);
mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_RSACHALLENGE, &m);
buffer_get_bignum2(&m, challenge);
buffer_free(&m);
return (challenge);
}
int
mm_auth_rsa_verify_response(Key *key, BIGNUM *p, u_char response[16])
{
Buffer m;
u_char *blob;
u_int blen;
int success = 0;
debug3("%s entering", __func__);
key->type = KEY_RSA; /* XXX cheat for key_to_blob */
if (key_to_blob(key, &blob, &blen) == 0)
fatal("%s: key_to_blob failed", __func__);
key->type = KEY_RSA1;
buffer_init(&m);
buffer_put_string(&m, blob, blen);
buffer_put_string(&m, response, 16);
xfree(blob);
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_RSARESPONSE, &m);
mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_RSARESPONSE, &m);
success = buffer_get_int(&m);
buffer_free(&m);
return (success);
}
static int
send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback,
int hint)
{
u_char *blob;
u_int bloblen, have_sig = 0;
debug3("send_pubkey_test");
if (key_to_blob(k, &blob, &bloblen) == 0) {
/* we cannot handle this key */
debug3("send_pubkey_test: cannot handle key");
return 0;
}
/* register callback for USERAUTH_PK_OK message */
authctxt->last_key_sign = sign_callback;
authctxt->last_key_hint = hint;
authctxt->last_key = k;
dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_cstring(authctxt->server_user);
packet_put_cstring(authctxt->service);
packet_put_cstring(authctxt->method->name);
packet_put_char(have_sig);
if (!(datafellows & SSH_BUG_PKAUTH))
packet_put_cstring(key_ssh_name(k));
packet_put_string(blob, bloblen);
xfree(blob);
packet_send();
return 1;
}
int
mm_sshkey_verify(const struct sshkey *key, const u_char *sig, size_t siglen,
const u_char *data, size_t datalen, u_int compat)
{
Buffer m;
u_char *blob;
u_int len;
u_int encoded_ret = 0;
debug3("%s entering", __func__);
/* Convert the key to a blob and the pass it over */
if (!key_to_blob(key, &blob, &len))
return (0);
buffer_init(&m);
buffer_put_string(&m, blob, len);
buffer_put_string(&m, sig, siglen);
buffer_put_string(&m, data, datalen);
free(blob);
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYVERIFY, &m);
debug3("%s: waiting for MONITOR_ANS_KEYVERIFY", __func__);
mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_KEYVERIFY, &m);
encoded_ret = buffer_get_int(&m);
buffer_free(&m);
if (encoded_ret != 0)
return SSH_ERR_SIGNATURE_INVALID;
return 0;
}
int
ssh_remove_identity(AuthenticationConnection *auth, Key *key)
{
Buffer msg;
int type;
u_char *blob;
u_int blen;
buffer_init(&msg);
if (key->type == KEY_RSA1) {
buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
buffer_put_int(&msg, BN_num_bits(key->rsa->n));
buffer_put_bignum(&msg, key->rsa->e);
buffer_put_bignum(&msg, key->rsa->n);
} else if (key->type == KEY_DSA || key->type == KEY_RSA) {
key_to_blob(key, &blob, &blen);
buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
buffer_put_string(&msg, blob, blen);
xfree(blob);
} else {
buffer_free(&msg);
return 0;
}
if (ssh_request_reply(auth, &msg, &msg) == 0) {
buffer_free(&msg);
return 0;
}
type = buffer_get_char(&msg);
buffer_free(&msg);
return decode_reply(type);
}
int
mm_answer_rsa_keyallowed(int sock, Buffer *m)
{
BIGNUM *client_n;
Key *key = NULL;
u_char *blob = NULL;
u_int blen = 0;
int allowed = 0;
debug3("%s entering", __func__);
auth_method = "rsa";
if (options.rsa_authentication && authctxt->valid) {
if ((client_n = BN_new()) == NULL)
fatal("%s: BN_new", __func__);
buffer_get_bignum2(m, client_n);
allowed = auth_rsa_key_allowed(authctxt->pw, client_n, &key);
BN_clear_free(client_n);
}
buffer_clear(m);
buffer_put_int(m, allowed);
buffer_put_int(m, forced_command != NULL);
/* clear temporarily storage (used by generate challenge) */
monitor_reset_key_state();
if (allowed && key != NULL) {
key->type = KEY_RSA; /* cheat for key_to_blob */
if (key_to_blob(key, &blob, &blen) == 0)
fatal("%s: key_to_blob failed", __func__);
buffer_put_string(m, blob, blen);
/* Save temporarily for comparison in verify */
key_blob = blob;
key_bloblen = blen;
key_blobtype = MM_RSAUSERKEY;
}
if (key != NULL)
key_free(key);
mm_append_debug(m);
mm_request_send(sock, MONITOR_ANS_RSAKEYALLOWED, m);
monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed);
monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 0);
return (0);
}
/* ask agent to sign data, returns -1 on error, 0 on success */
int
ssh_agent_sign(AuthenticationConnection *auth,
Key *key,
u_char **sigp, u_int *lenp,
u_char *data, u_int datalen)
{
extern int datafellows;
Buffer msg;
u_char *blob;
u_int blen;
int type, flags = 0;
int ret = -1;
if (key_to_blob(key, &blob, &blen) == 0)
return -1;
if (datafellows & SSH_BUG_SIGBLOB)
flags = SSH_AGENT_OLD_SIGNATURE;
buffer_init(&msg);
buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
buffer_put_string(&msg, blob, blen);
buffer_put_string(&msg, data, datalen);
buffer_put_int(&msg, flags);
xfree(blob);
if (ssh_request_reply(auth, &msg, &msg) == 0) {
buffer_free(&msg);
return -1;
}
type = buffer_get_char(&msg);
if (agent_failed(type)) {
log("Agent admitted failure to sign using the key.");
} else if (type != SSH2_AGENT_SIGN_RESPONSE) {
fatal("Bad authentication response: %d", type);
} else {
ret = 0;
*sigp = buffer_get_string(&msg, lenp);
}
buffer_free(&msg);
return ret;
}
int
mm_key_allowed(enum mm_keytype type, char *user, char *host, Key *key)
{
Buffer m;
u_char *blob;
u_int len;
int allowed = 0, have_forced = 0;
debug3("%s entering", __func__);
/* Convert the key to a blob and the pass it over */
if (!key_to_blob(key, &blob, &len))
return (0);
buffer_init(&m);
buffer_put_int(&m, type);
buffer_put_cstring(&m, user ? user : "");
buffer_put_cstring(&m, host ? host : "");
buffer_put_string(&m, blob, len);
xfree(blob);
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYALLOWED, &m);
debug3("%s: waiting for MONITOR_ANS_KEYALLOWED", __func__);
mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_KEYALLOWED, &m);
allowed = buffer_get_int(&m);
/* fake forced command */
auth_clear_options();
have_forced = buffer_get_int(&m);
forced_command = have_forced ? xstrdup("true") : NULL;
/* Send potential debug messages */
mm_send_debug(&m);
buffer_free(&m);
return (allowed);
}
static int
pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
int padding)
{
Key key;
u_char *blob, *signature = NULL;
u_int blen, slen = 0;
int ret = -1;
Buffer msg;
if (padding != RSA_PKCS1_PADDING)
return (-1);
key.type = KEY_RSA;
key.rsa = rsa;
if (key_to_blob(&key, &blob, &blen) == 0)
return -1;
buffer_init(&msg);
buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
buffer_put_string(&msg, blob, blen);
buffer_put_string(&msg, from, flen);
buffer_put_int(&msg, 0);
free(blob);
send_msg(&msg);
buffer_clear(&msg);
if (recv_msg(&msg) == SSH2_AGENT_SIGN_RESPONSE) {
signature = buffer_get_string(&msg, &slen);
if (slen <= (u_int)RSA_size(rsa)) {
memcpy(to, signature, slen);
ret = slen;
}
free(signature);
}
buffer_free(&msg);
return (ret);
}
char* key_fingerprint_raw(Key *k, enum fp_type dgst_type, int *dgst_raw_length)
{
const EVP_MD *md = NULL;
EVP_MD_CTX ctx;
char *blob = NULL;
char *retval = NULL;
int len = 0;
int nlen, elen;
RSA *rsa;
*dgst_raw_length = 0;
switch (dgst_type) {
case SSH_FP_MD5:
md = EVP_md5();
break;
case SSH_FP_SHA1:
md = EVP_sha1();
break;
case SSH_FP_SHA256:
md = EVP_sha256();
break;
default:
md = EVP_md5();
}
switch (k->type) {
case KEY_RSA1:
rsa = make_key(NULL, k->bits, k->exp, k->mod);
nlen = BN_num_bytes(rsa->n);
elen = BN_num_bytes(rsa->e);
len = nlen + elen;
blob = malloc(len);
if (blob == NULL) {
// TODO:
}
BN_bn2bin(rsa->n, blob);
BN_bn2bin(rsa->e, blob + nlen);
RSA_free(rsa);
break;
case KEY_DSA:
case KEY_RSA:
case KEY_ECDSA256:
case KEY_ECDSA384:
case KEY_ECDSA521:
case KEY_ED25519:
key_to_blob(k, &blob, &len);
break;
case KEY_UNSPEC:
return retval;
break;
default:
//fatal("key_fingerprint_raw: bad key type %d", k->type);
break;
}
if (blob != NULL) {
retval = malloc(EVP_MAX_MD_SIZE);
if (retval == NULL) {
// TODO:
}
EVP_DigestInit(&ctx, md);
EVP_DigestUpdate(&ctx, blob, len);
EVP_DigestFinal(&ctx, retval, dgst_raw_length);
memset(blob, 0, len);
free(blob);
} else {
//fatal("key_fingerprint_raw: blob is null");
}
return retval;
}
void
kexgex_server(Kex *kex)
{
BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
Key *server_host_public, *server_host_private;
DH *dh;
u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
u_int sbloblen, klen, slen, hashlen;
int omin = -1, min = -1, omax = -1, max = -1, onbits = -1, nbits = -1;
int type, kout;
if (kex->load_host_public_key == NULL ||
kex->load_host_private_key == NULL)
fatal("Cannot load hostkey");
server_host_public = kex->load_host_public_key(kex->hostkey_type);
if (server_host_public == NULL)
fatal("Unsupported hostkey type %d", kex->hostkey_type);
server_host_private = kex->load_host_private_key(kex->hostkey_type);
type = packet_read();
switch (type) {
case SSH2_MSG_KEX_DH_GEX_REQUEST:
debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
omin = min = packet_get_int();
onbits = nbits = packet_get_int();
omax = max = packet_get_int();
min = MAX(DH_GRP_MIN, min);
max = MIN(DH_GRP_MAX, max);
nbits = MAX(DH_GRP_MIN, nbits);
nbits = MIN(DH_GRP_MAX, nbits);
break;
case SSH2_MSG_KEX_DH_GEX_REQUEST_OLD:
debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received");
onbits = nbits = packet_get_int();
/* unused for old GEX */
omin = min = DH_GRP_MIN;
omax = max = DH_GRP_MAX;
break;
default:
fatal("protocol error during kex, no DH_GEX_REQUEST: %d", type);
}
packet_check_eom();
if (omax < omin || onbits < omin || omax < onbits)
fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
omin, onbits, omax);
/* Contact privileged parent */
dh = PRIVSEP(choose_dh(min, nbits, max));
if (dh == NULL)
packet_disconnect("Protocol error: no matching DH grp found");
debug("SSH2_MSG_KEX_DH_GEX_GROUP sent");
packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
packet_put_bignum2(dh->p);
packet_put_bignum2(dh->g);
packet_send();
/* flush */
packet_write_wait();
/* Compute our exchange value in parallel with the client */
dh_gen_key(dh, kex->we_need * 8);
debug("expecting SSH2_MSG_KEX_DH_GEX_INIT");
packet_read_expect(SSH2_MSG_KEX_DH_GEX_INIT);
/* key, cert */
if ((dh_client_pub = BN_new()) == NULL)
fatal("dh_client_pub == NULL");
packet_get_bignum2(dh_client_pub);
packet_check_eom();
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_client_pub= ");
BN_print_fp(stderr, dh_client_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_client_pub));
#endif
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, dh->pub_key);
fprintf(stderr, "\n");
#endif
if (!dh_pub_is_valid(dh, dh_client_pub))
packet_disconnect("bad client public DH value");
klen = DH_size(dh);
kbuf = xmalloc(klen);
if ((kout = DH_compute_key(kbuf, dh_client_pub, dh)) < 0)
fatal("DH_compute_key: failed");
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if ((shared_secret = BN_new()) == NULL)
fatal("kexgex_server: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexgex_server: BN_bin2bn failed");
memset(kbuf, 0, klen);
free(kbuf);
key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
omin = min = omax = max = -1;
/* calc H */
kexgex_hash(
kex->evp_md,
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
buffer_ptr(&kex->my), buffer_len(&kex->my),
server_host_key_blob, sbloblen,
omin, onbits, omax,
dh->p, dh->g,
dh_client_pub,
dh->pub_key,
shared_secret,
&hash, &hashlen
);
BN_clear_free(dh_client_pub);
/* save session id := H */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
/* sign H */
kex->sign(server_host_private, server_host_public, &signature, &slen,
hash, hashlen);
/* destroy_sensitive_data(); */
/* send server hostkey, DH pubkey 'f' and singed H */
debug("SSH2_MSG_KEX_DH_GEX_REPLY sent");
packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
packet_put_string(server_host_key_blob, sbloblen);
packet_put_bignum2(dh->pub_key); /* f */
packet_put_string(signature, slen);
packet_send();
free(signature);
free(server_host_key_blob);
/* have keys, free DH */
DH_free(dh);
kex_derive_keys(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
void
kexdh_server(Kex *kex)
{
BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
DH *dh;
Key *server_host_key;
u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
u_int sbloblen, klen, kout, hashlen;
u_int slen;
/* generate server DH public key */
switch (kex->kex_type) {
case KEX_DH_GRP1_SHA1:
dh = dh_new_group1();
break;
case KEX_DH_GRP14_SHA1:
dh = dh_new_group14();
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
dh_gen_key(dh, kex->we_need * 8);
debug("expecting SSH2_MSG_KEXDH_INIT");
packet_read_expect(SSH2_MSG_KEXDH_INIT);
if (kex->load_host_key == NULL)
fatal("Cannot load hostkey");
server_host_key = kex->load_host_key(kex->hostkey_type);
if (server_host_key == NULL)
fatal("Unsupported hostkey type %d", kex->hostkey_type);
/* key, cert */
if ((dh_client_pub = BN_new()) == NULL)
fatal("dh_client_pub == NULL");
packet_get_bignum2(dh_client_pub);
packet_check_eom();
#ifdef DEBUG_KEXDH
fprintf(stderr, "dh_client_pub= ");
BN_print_fp(stderr, dh_client_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_client_pub));
#endif
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, dh->pub_key);
fprintf(stderr, "\n");
#endif
if (!dh_pub_is_valid(dh, dh_client_pub))
packet_disconnect("bad client public DH value");
klen = DH_size(dh);
kbuf = xmalloc(klen);
kout = DH_compute_key(kbuf, dh_client_pub, dh);
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, kout);
#endif
if ((shared_secret = BN_new()) == NULL)
fatal("kexdh_server: BN_new failed");
BN_bin2bn(kbuf, kout, shared_secret);
memset(kbuf, 0, klen);
xfree(kbuf);
key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);
/* calc H */
kex_dh_hash(
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
buffer_ptr(&kex->my), buffer_len(&kex->my),
server_host_key_blob, sbloblen,
dh_client_pub,
dh->pub_key,
shared_secret,
&hash, &hashlen
);
BN_clear_free(dh_client_pub);
/* save session id := H */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
/* sign H */
PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, hashlen));
/* destroy_sensitive_data(); */
/* send server hostkey, DH pubkey 'f' and singed H */
packet_start(SSH2_MSG_KEXDH_REPLY);
packet_put_string(server_host_key_blob, sbloblen);
packet_put_bignum2(dh->pub_key); /* f */
packet_put_string(signature, slen);
packet_send();
xfree(signature);
xfree(server_host_key_blob);
/* have keys, free DH */
DH_free(dh);
kex_derive_keys(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
static int
sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback)
{
Buffer b;
u_char *blob, *signature;
u_int bloblen, slen;
int skip = 0;
int ret = -1;
int have_sig = 1;
debug3("sign_and_send_pubkey");
if (key_to_blob(k, &blob, &bloblen) == 0) {
/* we cannot handle this key */
debug3("sign_and_send_pubkey: cannot handle key");
return 0;
}
/* data to be signed */
buffer_init(&b);
if (datafellows & SSH_OLD_SESSIONID) {
buffer_append(&b, session_id2, session_id2_len);
skip = session_id2_len;
} else {
buffer_put_string(&b, session_id2, session_id2_len);
skip = buffer_len(&b);
}
buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
buffer_put_cstring(&b, authctxt->server_user);
buffer_put_cstring(&b,
datafellows & SSH_BUG_PKSERVICE ?
"ssh-userauth" :
authctxt->service);
if (datafellows & SSH_BUG_PKAUTH) {
buffer_put_char(&b, have_sig);
} else {
buffer_put_cstring(&b, authctxt->method->name);
buffer_put_char(&b, have_sig);
buffer_put_cstring(&b, key_ssh_name(k));
}
buffer_put_string(&b, blob, bloblen);
/* generate signature */
ret = (*sign_callback)(authctxt, k, &signature, &slen,
buffer_ptr(&b), buffer_len(&b));
if (ret == -1) {
xfree(blob);
buffer_free(&b);
return 0;
}
#ifdef DEBUG_PK
buffer_dump(&b);
#endif
if (datafellows & SSH_BUG_PKSERVICE) {
buffer_clear(&b);
buffer_append(&b, session_id2, session_id2_len);
skip = session_id2_len;
buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
buffer_put_cstring(&b, authctxt->server_user);
buffer_put_cstring(&b, authctxt->service);
buffer_put_cstring(&b, authctxt->method->name);
buffer_put_char(&b, have_sig);
if (!(datafellows & SSH_BUG_PKAUTH))
buffer_put_cstring(&b, key_ssh_name(k));
buffer_put_string(&b, blob, bloblen);
}
xfree(blob);
/* append signature */
buffer_put_string(&b, signature, slen);
xfree(signature);
/* skip session id and packet type */
if (buffer_len(&b) < skip + 1)
fatal("userauth_pubkey: internal error");
buffer_consume(&b, skip + 1);
/* put remaining data from buffer into packet */
packet_start(SSH2_MSG_USERAUTH_REQUEST);
packet_put_raw(buffer_ptr(&b), buffer_len(&b));
buffer_free(&b);
packet_send();
return 1;
}
void
kexecdh_server(Kex *kex)
{
EC_POINT *client_public;
EC_KEY *server_key;
const EC_GROUP *group;
BIGNUM *shared_secret;
Key *server_host_private, *server_host_public;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *kbuf, *hash;
u_int klen, slen, sbloblen, hashlen;
int curve_nid;
if ((curve_nid = kex_ecdh_name_to_nid(kex->name)) == -1)
fatal("%s: unsupported ECDH curve \"%s\"", __func__, kex->name);
if ((server_key = EC_KEY_new_by_curve_name(curve_nid)) == NULL)
fatal("%s: EC_KEY_new_by_curve_name failed", __func__);
if (EC_KEY_generate_key(server_key) != 1)
fatal("%s: EC_KEY_generate_key failed", __func__);
group = EC_KEY_get0_group(server_key);
#ifdef DEBUG_KEXECDH
fputs("server private key:\n", stderr);
key_dump_ec_key(server_key);
#endif
if (kex->load_host_public_key == NULL ||
kex->load_host_private_key == NULL)
fatal("Cannot load hostkey");
server_host_public = kex->load_host_public_key(kex->hostkey_type);
if (server_host_public == NULL)
fatal("Unsupported hostkey type %d", kex->hostkey_type);
server_host_private = kex->load_host_private_key(kex->hostkey_type);
if (server_host_private == NULL)
fatal("Missing private key for hostkey type %d",
kex->hostkey_type);
debug("expecting SSH2_MSG_KEX_ECDH_INIT");
packet_read_expect(SSH2_MSG_KEX_ECDH_INIT);
if ((client_public = EC_POINT_new(group)) == NULL)
fatal("%s: EC_POINT_new failed", __func__);
packet_get_ecpoint(group, client_public);
packet_check_eom();
if (key_ec_validate_public(group, client_public) != 0)
fatal("%s: invalid client public key", __func__);
#ifdef DEBUG_KEXECDH
fputs("client public key:\n", stderr);
key_dump_ec_point(group, client_public);
#endif
/* Calculate shared_secret */
klen = (EC_GROUP_get_degree(group) + 7) / 8;
kbuf = xmalloc(klen);
if (ECDH_compute_key(kbuf, klen, client_public,
server_key, NULL) != (int)klen)
fatal("%s: ECDH_compute_key failed", __func__);
#ifdef DEBUG_KEXDH
dump_digest("shared secret", kbuf, klen);
#endif
if ((shared_secret = BN_new()) == NULL)
fatal("%s: BN_new failed", __func__);
if (BN_bin2bn(kbuf, klen, shared_secret) == NULL)
fatal("%s: BN_bin2bn failed", __func__);
memset(kbuf, 0, klen);
xfree(kbuf);
/* calc H */
key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
kex_ecdh_hash(
kex->evp_md,
group,
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
buffer_ptr(&kex->my), buffer_len(&kex->my),
server_host_key_blob, sbloblen,
client_public,
EC_KEY_get0_public_key(server_key),
shared_secret,
&hash, &hashlen
);
EC_POINT_clear_free(client_public);
/* save session id := H */
if (kex->session_id == NULL) {
kex->session_id_len = hashlen;
kex->session_id = xmalloc(kex->session_id_len);
memcpy(kex->session_id, hash, kex->session_id_len);
}
/* sign H */
if (PRIVSEP(key_sign(server_host_private, &signature, &slen,
hash, hashlen)) < 0)
fatal("kexdh_server: key_sign failed");
/* destroy_sensitive_data(); */
/* send server hostkey, ECDH pubkey 'Q_S' and signed H */
packet_start(SSH2_MSG_KEX_ECDH_REPLY);
packet_put_string(server_host_key_blob, sbloblen);
packet_put_ecpoint(group, EC_KEY_get0_public_key(server_key));
packet_put_string(signature, slen);
packet_send();
xfree(signature);
xfree(server_host_key_blob);
/* have keys, free server key */
EC_KEY_free(server_key);
kex_derive_keys(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
static void
userauth_pubkey(Authctxt *authctxt)
{
Buffer b;
Key *key = NULL;
char *pkalg;
u_char *pkblob, *sig;
u_int alen, blen, slen;
int have_sig, pktype;
int authenticated = 0;
if (!authctxt || !authctxt->method)
fatal("%s: missing context", __func__);
have_sig = packet_get_char();
if (datafellows & SSH_BUG_PKAUTH) {
debug2("userauth_pubkey: SSH_BUG_PKAUTH");
/* no explicit pkalg given */
pkblob = packet_get_string(&blen);
buffer_init(&b);
buffer_append(&b, pkblob, blen);
/* so we have to extract the pkalg from the pkblob */
pkalg = buffer_get_string(&b, &alen);
buffer_free(&b);
} else {
pkalg = packet_get_string(&alen);
pkblob = packet_get_string(&blen);
}
pktype = key_type_from_name(pkalg);
if (pktype == KEY_UNSPEC) {
/* this is perfectly legal */
log("userauth_pubkey: unsupported public key algorithm: %s",
pkalg);
goto done;
}
key = key_from_blob(pkblob, blen);
if (key == NULL) {
error("userauth_pubkey: cannot decode key: %s", pkalg);
goto done;
}
if (key->type != pktype) {
error("userauth_pubkey: type mismatch for decoded key "
"(received %d, expected %d)", key->type, pktype);
goto done;
}
/* Detect and count abandonment */
if (authctxt->method->method_data) {
Key *prev_key;
unsigned char *prev_pkblob;
int prev_blen;
/*
* Check for earlier test of a key that was allowed but
* not followed up with a pubkey req for the same pubkey
* and with a signature.
*/
prev_key = authctxt->method->method_data;
if ((prev_blen = key_to_blob(prev_key,
&prev_pkblob, NULL))) {
if (prev_blen != blen ||
memcmp(prev_pkblob, pkblob, blen) != 0) {
authctxt->method->abandons++;
authctxt->method->attempts++;
}
}
key_free(prev_key);
authctxt->method->method_data = NULL;
}
if (have_sig) {
sig = packet_get_string(&slen);
packet_check_eom();
buffer_init(&b);
if (datafellows & SSH_OLD_SESSIONID) {
buffer_append(&b, session_id2, session_id2_len);
} else {
buffer_put_string(&b, session_id2, session_id2_len);
}
/* reconstruct packet */
buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
buffer_put_cstring(&b, authctxt->user);
buffer_put_cstring(&b,
datafellows & SSH_BUG_PKSERVICE ?
"ssh-userauth" :
authctxt->service);
if (datafellows & SSH_BUG_PKAUTH) {
buffer_put_char(&b, have_sig);
} else {
buffer_put_cstring(&b, "publickey");
buffer_put_char(&b, have_sig);
buffer_put_cstring(&b, pkalg);
}
buffer_put_string(&b, pkblob, blen);
#ifdef DEBUG_PK
buffer_dump(&b);
#endif
/* test for correct signature */
if (user_key_allowed(authctxt->pw, key) &&
key_verify(key, sig, slen, buffer_ptr(&b),
buffer_len(&b)) == 1) {
authenticated = 1;
}
authctxt->method->postponed = 0;
buffer_free(&b);
xfree(sig);
} else {
debug("test whether pkalg/pkblob are acceptable");
packet_check_eom();
/* XXX fake reply and always send PK_OK ? */
/*
* XXX this allows testing whether a user is allowed
* to login: if you happen to have a valid pubkey this
* message is sent. the message is NEVER sent at all
* if a user is not allowed to login. is this an
* issue? -markus
*/
if (user_key_allowed(authctxt->pw, key)) {
packet_start(SSH2_MSG_USERAUTH_PK_OK);
packet_put_string(pkalg, alen);
packet_put_string(pkblob, blen);
packet_send();
packet_write_wait();
authctxt->method->postponed = 1;
/*
* Remember key that was tried so we can
* correctly detect abandonment. See above.
*/
authctxt->method->method_data = (void *) key;
key = NULL;
}
}
if (authenticated != 1)
auth_clear_options();
done:
/*
* XXX TODO: add config options for specifying users for whom
* this userauth is insufficient and what userauths may
* continue.
*/
#ifdef USE_PAM
if (authenticated) {
if (!do_pam_non_initial_userauth(authctxt))
authenticated = 0;
}
#endif /* USE_PAM */
debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
if (key != NULL)
key_free(key);
xfree(pkalg);
xfree(pkblob);
#ifdef HAVE_CYGWIN
if (check_nt_auth(0, authctxt->pw) == 0)
return;
#endif
if (authenticated)
authctxt->method->authenticated = 1;
}
