int
kexgex_hash(
int hash_alg,
const char *client_version_string,
const char *server_version_string,
const u_char *ckexinit, size_t ckexinitlen,
const u_char *skexinit, size_t skexinitlen,
const u_char *serverhostkeyblob, size_t sbloblen,
int min, int wantbits, int max,
const BIGNUM *prime,
const BIGNUM *gen,
const BIGNUM *client_dh_pub,
const BIGNUM *server_dh_pub,
const BIGNUM *shared_secret,
u_char **hash, size_t *hashlen)
{
struct sshbuf *b;
static u_char digest[SSH_DIGEST_MAX_LENGTH];
int r;
if ((b = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_cstring(b, client_version_string)) != 0 ||
(r = sshbuf_put_cstring(b, server_version_string)) != 0 ||
/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
(r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 ||
(r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
(r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 ||
(r = sshbuf_put_u32(b, skexinitlen+1)) != 0 ||
(r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
(r = sshbuf_put(b, skexinit, skexinitlen)) != 0 ||
(r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 ||
(min != -1 && (r = sshbuf_put_u32(b, min)) != 0) ||
(r = sshbuf_put_u32(b, wantbits)) != 0 ||
(max != -1 && (r = sshbuf_put_u32(b, max)) != 0) ||
(r = sshbuf_put_bignum2(b, prime)) != 0 ||
(r = sshbuf_put_bignum2(b, gen)) != 0 ||
(r = sshbuf_put_bignum2(b, client_dh_pub)) != 0 ||
(r = sshbuf_put_bignum2(b, server_dh_pub)) != 0 ||
(r = sshbuf_put_bignum2(b, shared_secret)) != 0) {
sshbuf_free(b);
return r;
}
#ifdef DEBUG_KEXDH
sshbuf_dump(b, stderr);
#endif
if (ssh_digest_buffer(hash_alg, b, digest, sizeof(digest)) != 0) {
sshbuf_free(b);
return SSH_ERR_LIBCRYPTO_ERROR;
}
sshbuf_free(b);
*hash = digest;
*hashlen = ssh_digest_bytes(hash_alg);
#ifdef DEBUG_KEXDH
dump_digest("hash", digest, *hashlen);
#endif
return 0;
}
void
dump_digest(char *msg, u_char *digest, int len)
{
struct sshbuf *b;
fprintf(stderr, "%s\n", msg);
if ((b = sshbuf_from(digest, len)) != NULL)
sshbuf_dump(b, stderr);
sshbuf_free(b);
}
int
kex_ecdh_hash(
const EVP_MD *evp_md,
const EC_GROUP *ec_group,
const char *client_version_string,
const char *server_version_string,
const u_char *ckexinit, size_t ckexinitlen,
const u_char *skexinit, size_t skexinitlen,
const u_char *serverhostkeyblob, size_t sbloblen,
const EC_POINT *client_dh_pub,
const EC_POINT *server_dh_pub,
const BIGNUM *shared_secret,
u_char **hash, size_t *hashlen)
{
struct sshbuf *b;
EVP_MD_CTX md;
static u_char digest[EVP_MAX_MD_SIZE];
int r;
if ((b = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_cstring(b, client_version_string)) != 0 ||
(r = sshbuf_put_cstring(b, server_version_string)) != 0 ||
/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
(r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 ||
(r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
(r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 ||
(r = sshbuf_put_u32(b, skexinitlen+1)) != 0 ||
(r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
(r = sshbuf_put(b, skexinit, skexinitlen)) != 0 ||
(r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 ||
(r = sshbuf_put_ec(b, client_dh_pub, ec_group)) != 0 ||
(r = sshbuf_put_ec(b, server_dh_pub, ec_group)) != 0 ||
(r = sshbuf_put_bignum2(b, shared_secret)) != 0) {
sshbuf_free(b);
return r;
}
#ifdef DEBUG_KEX
sshbuf_dump(b, stderr);
#endif
if (EVP_DigestInit(&md, evp_md) != 1 ||
EVP_DigestUpdate(&md, sshbuf_ptr(b), sshbuf_len(b)) != 1 ||
EVP_DigestFinal(&md, digest, NULL) != 1) {
sshbuf_free(b);
return SSH_ERR_LIBCRYPTO_ERROR;
}
sshbuf_free(b);
#ifdef DEBUG_KEX
dump_digest("hash", digest, EVP_MD_size(evp_md));
#endif
*hash = digest;
*hashlen = EVP_MD_size(evp_md);
return 0;
}
void
dump_digest(char *msg, u_char *digest, int len)
{
struct sshbuf *b;
fprintf(stderr, "%s\n", msg);
if ((b = sshbuf_new()) == NULL)
return;
if (sshbuf_put(b, digest, len) == 0)
sshbuf_dump(b, stderr);
sshbuf_free(b);
}
int
kex_ecdh_hash(
int hash_alg,
const EC_GROUP *ec_group,
const char *client_version_string,
const char *server_version_string,
const u_char *ckexinit, size_t ckexinitlen,
const u_char *skexinit, size_t skexinitlen,
const u_char *serverhostkeyblob, size_t sbloblen,
const EC_POINT *client_dh_pub,
const EC_POINT *server_dh_pub,
const BIGNUM *shared_secret,
u_char *hash, size_t *hashlen)
{
struct sshbuf *b;
int r;
if (*hashlen < ssh_digest_bytes(hash_alg))
return SSH_ERR_INVALID_ARGUMENT;
if ((b = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_cstring(b, client_version_string)) != 0 ||
(r = sshbuf_put_cstring(b, server_version_string)) != 0 ||
/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
(r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 ||
(r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
(r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 ||
(r = sshbuf_put_u32(b, skexinitlen+1)) != 0 ||
(r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
(r = sshbuf_put(b, skexinit, skexinitlen)) != 0 ||
(r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 ||
(r = sshbuf_put_ec(b, client_dh_pub, ec_group)) != 0 ||
(r = sshbuf_put_ec(b, server_dh_pub, ec_group)) != 0 ||
(r = sshbuf_put_bignum2(b, shared_secret)) != 0) {
sshbuf_free(b);
return r;
}
#ifdef DEBUG_KEX
sshbuf_dump(b, stderr);
#endif
if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {
sshbuf_free(b);
return SSH_ERR_LIBCRYPTO_ERROR;
}
sshbuf_free(b);
*hashlen = ssh_digest_bytes(hash_alg);
#ifdef DEBUG_KEX
dump_digest("hash", hash, *hashlen);
#endif
return 0;
}
void
sshbuf_misc_tests(void)
{
struct sshbuf *p1;
char tmp[512], *p;
FILE *out;
size_t sz;
TEST_START("sshbuf_dump");
out = tmpfile();
ASSERT_PTR_NE(out, NULL);
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_put_u32(p1, 0x12345678), 0);
sshbuf_dump(p1, out);
fflush(out);
rewind(out);
sz = fread(tmp, 1, sizeof(tmp), out);
ASSERT_INT_EQ(ferror(out), 0);
ASSERT_INT_NE(feof(out), 0);
ASSERT_SIZE_T_GT(sz, 0);
tmp[sz] = '\0';
ASSERT_PTR_NE(strstr(tmp, "12 34 56 78"), NULL);
fclose(out);
sshbuf_free(p1);
TEST_DONE();
TEST_START("sshbuf_dtob16");
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_put_u32(p1, 0x12345678), 0);
p = sshbuf_dtob16(p1);
ASSERT_PTR_NE(p, NULL);
ASSERT_STRING_EQ(p, "12345678");
free(p);
sshbuf_free(p1);
TEST_DONE();
TEST_START("sshbuf_dtob64 len 1");
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_put_u8(p1, 0x11), 0);
p = sshbuf_dtob64(p1);
ASSERT_PTR_NE(p, NULL);
ASSERT_STRING_EQ(p, "EQ==");
free(p);
sshbuf_free(p1);
TEST_DONE();
TEST_START("sshbuf_dtob64 len 2");
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_put_u8(p1, 0x11), 0);
ASSERT_INT_EQ(sshbuf_put_u8(p1, 0x22), 0);
p = sshbuf_dtob64(p1);
ASSERT_PTR_NE(p, NULL);
ASSERT_STRING_EQ(p, "ESI=");
free(p);
sshbuf_free(p1);
TEST_DONE();
TEST_START("sshbuf_dtob64 len 3");
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_put_u8(p1, 0x11), 0);
ASSERT_INT_EQ(sshbuf_put_u8(p1, 0x22), 0);
ASSERT_INT_EQ(sshbuf_put_u8(p1, 0x33), 0);
p = sshbuf_dtob64(p1);
ASSERT_PTR_NE(p, NULL);
ASSERT_STRING_EQ(p, "ESIz");
free(p);
sshbuf_free(p1);
TEST_DONE();
TEST_START("sshbuf_dtob64 len 8191");
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_reserve(p1, 8192, NULL), 0);
bzero(sshbuf_mutable_ptr(p1), 8192);
p = sshbuf_dtob64(p1);
ASSERT_PTR_NE(p, NULL);
ASSERT_SIZE_T_EQ(strlen(p), ((8191 + 2) / 3) * 4);
free(p);
sshbuf_free(p1);
TEST_DONE();
TEST_START("sshbuf_b64tod len 1");
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_b64tod(p1, "0A=="), 0);
ASSERT_SIZE_T_EQ(sshbuf_len(p1), 1);
ASSERT_U8_EQ(*sshbuf_ptr(p1), 0xd0);
sshbuf_free(p1);
TEST_DONE();
TEST_START("sshbuf_b64tod len 2");
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_b64tod(p1, "0A8="), 0);
ASSERT_SIZE_T_EQ(sshbuf_len(p1), 2);
ASSERT_U16_EQ(PEEK_U16(sshbuf_ptr(p1)), 0xd00f);
sshbuf_free(p1);
TEST_DONE();
TEST_START("sshbuf_b64tod len 4");
p1 = sshbuf_new();
ASSERT_PTR_NE(p1, NULL);
ASSERT_INT_EQ(sshbuf_b64tod(p1, "0A/QDw=="), 0);
ASSERT_SIZE_T_EQ(sshbuf_len(p1), 4);
ASSERT_U32_EQ(PEEK_U32(sshbuf_ptr(p1)), 0xd00fd00f);
sshbuf_free(p1);
TEST_DONE();
}
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;
}
