/*
* Make packets from buffered stdout data, and buffer it for sending to the
* client.
*/
static void
make_packets_from_stdout_data(void)
{
u_int len;
/* Send buffered stdout data to the client. */
while (buffer_len(&stdout_buffer) > 0 &&
packet_not_very_much_data_to_write()) {
len = buffer_len(&stdout_buffer);
if (packet_is_interactive()) {
if (len > 512)
len = 512;
} else {
/* Keep the packets at reasonable size. */
if (len > packet_get_maxsize())
len = packet_get_maxsize();
}
packet_start(SSH_SMSG_STDOUT_DATA);
packet_put_string(buffer_ptr(&stdout_buffer), len);
packet_send();
buffer_consume(&stdout_buffer, len);
stdout_bytes += len;
}
}
static void
client_alive_check(void)
{
int channel_id;
/* timeout, check to see how many we have had */
if (packet_inc_alive_timeouts() > options.client_alive_count_max) {
logit("Timeout, client not responding.");
cleanup_exit(255);
}
/*
* send a bogus global/channel request with "wantreply",
* we should get back a failure
*/
if ((channel_id = channel_find_open()) == -1) {
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("*****@*****.**");
packet_put_char(1); /* boolean: want reply */
} else {
channel_request_start(channel_id, "*****@*****.**", 1);
}
packet_send();
}
static void
server_input_global_request(int type, u_int32_t seq, void *ctxt)
{
char *rtype;
int want_reply;
int success = 0, allocated_listen_port = 0;
rtype = packet_get_string(NULL);
want_reply = packet_get_char();
debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
/* -R style forwarding */
if (strcmp(rtype, "tcpip-forward") == 0) {
struct passwd *pw;
char *listen_address;
u_short listen_port;
pw = the_authctxt->pw;
if (pw == NULL || !the_authctxt->valid)
fatal("server_input_global_request: no/invalid user");
listen_address = packet_get_string(NULL);
listen_port = (u_short)packet_get_int();
debug("server_input_global_request: tcpip-forward listen %s port %d",
listen_address, listen_port);
/* check permissions */
if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
no_port_forwarding_flag ||
(!want_reply && listen_port == 0)
#ifndef NO_IPPORT_RESERVED_CONCEPT
|| (listen_port != 0 && listen_port < IPPORT_RESERVED &&
pw->pw_uid != 0)
#endif
) {
success = 0;
packet_send_debug("Server has disabled port forwarding.");
} else {
/* Start listening on the port */
success = channel_setup_remote_fwd_listener(
listen_address, listen_port,
&allocated_listen_port, options.gateway_ports);
}
free(listen_address);
} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
char *cancel_address;
u_short cancel_port;
cancel_address = packet_get_string(NULL);
cancel_port = (u_short)packet_get_int();
debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
cancel_address, cancel_port);
success = channel_cancel_rport_listener(cancel_address,
cancel_port);
free(cancel_address);
} else if (strcmp(rtype, "*****@*****.**") == 0) {
no_more_sessions = 1;
success = 1;
}
if (want_reply) {
packet_start(success ?
SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
if (success && allocated_listen_port > 0)
packet_put_int(allocated_listen_port);
packet_send();
packet_write_wait();
}
free(rtype);
}
static int
ssh_session(void)
{
int type;
int interactive = 0;
int have_tty = 0;
struct winsize ws;
char *cp;
const char *display;
/* Enable compression if requested. */
if (options.compression) {
debug("Requesting compression at level %d.",
options.compression_level);
if (options.compression_level < 1 ||
options.compression_level > 9)
fatal("Compression level must be from 1 (fast) to "
"9 (slow, best).");
/* Send the request. */
packet_start(SSH_CMSG_REQUEST_COMPRESSION);
packet_put_int(options.compression_level);
packet_send();
packet_write_wait();
type = packet_read();
if (type == SSH_SMSG_SUCCESS)
packet_start_compression(options.compression_level);
else if (type == SSH_SMSG_FAILURE)
logit("Warning: Remote host refused compression.");
else
packet_disconnect("Protocol error waiting for "
"compression response.");
}
/* Allocate a pseudo tty if appropriate. */
if (tty_flag) {
debug("Requesting pty.");
/* Start the packet. */
packet_start(SSH_CMSG_REQUEST_PTY);
/* Store TERM in the packet. There is no limit on the
length of the string. */
cp = getenv("TERM");
if (!cp)
cp = "";
packet_put_cstring(cp);
/* Store window size in the packet. */
if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
memset(&ws, 0, sizeof(ws));
packet_put_int((u_int)ws.ws_row);
packet_put_int((u_int)ws.ws_col);
packet_put_int((u_int)ws.ws_xpixel);
packet_put_int((u_int)ws.ws_ypixel);
/* Store tty modes in the packet. */
tty_make_modes(fileno(stdin), NULL);
/* Send the packet, and wait for it to leave. */
packet_send();
packet_write_wait();
/* Read response from the server. */
type = packet_read();
if (type == SSH_SMSG_SUCCESS) {
interactive = 1;
have_tty = 1;
} else if (type == SSH_SMSG_FAILURE)
logit("Warning: Remote host failed or refused to "
"allocate a pseudo tty.");
else
packet_disconnect("Protocol error waiting for pty "
"request response.");
}
/* Request X11 forwarding if enabled and DISPLAY is set. */
display = getenv("DISPLAY");
if (options.forward_x11 && display != NULL) {
char *proto, *data;
/* Get reasonable local authentication information. */
client_x11_get_proto(display, options.xauth_location,
options.forward_x11_trusted,
options.forward_x11_timeout,
&proto, &data);
/* Request forwarding with authentication spoofing. */
debug("Requesting X11 forwarding with authentication "
"spoofing.");
x11_request_forwarding_with_spoofing(0, display, proto,
data, 0);
/* Read response from the server. */
type = packet_read();
if (type == SSH_SMSG_SUCCESS) {
interactive = 1;
} else if (type == SSH_SMSG_FAILURE) {
logit("Warning: Remote host denied X11 forwarding.");
} else {
packet_disconnect("Protocol error waiting for X11 "
"forwarding");
}
}
/* Tell the packet module whether this is an interactive session. */
packet_set_interactive(interactive,
options.ip_qos_interactive, options.ip_qos_bulk);
/* Request authentication agent forwarding if appropriate. */
check_agent_present();
if (options.forward_agent) {
debug("Requesting authentication agent forwarding.");
auth_request_forwarding();
/* Read response from the server. */
type = packet_read();
packet_check_eom();
if (type != SSH_SMSG_SUCCESS)
logit("Warning: Remote host denied authentication agent forwarding.");
}
/* Initiate port forwardings. */
ssh_init_stdio_forwarding();
ssh_init_forwarding();
/* Execute a local command */
if (options.local_command != NULL &&
options.permit_local_command)
ssh_local_cmd(options.local_command);
/*
* If requested and we are not interested in replies to remote
* forwarding requests, then let ssh continue in the background.
*/
if (fork_after_authentication_flag) {
if (options.exit_on_forward_failure &&
options.num_remote_forwards > 0) {
debug("deferring postauth fork until remote forward "
"confirmation received");
} else
fork_postauth();
}
/*
* If a command was specified on the command line, execute the
* command now. Otherwise request the server to start a shell.
*/
if (buffer_len(&command) > 0) {
int len = buffer_len(&command);
if (len > 900)
len = 900;
debug("Sending command: %.*s", len,
(u_char *)buffer_ptr(&command));
packet_start(SSH_CMSG_EXEC_CMD);
packet_put_string(buffer_ptr(&command), buffer_len(&command));
packet_send();
packet_write_wait();
} else {
debug("Requesting shell.");
packet_start(SSH_CMSG_EXEC_SHELL);
packet_send();
packet_write_wait();
}
/* Enter the interactive session. */
return client_loop(have_tty, tty_flag ?
options.escape_char : SSH_ESCAPECHAR_NONE, 0);
}
/*
* Performs authentication of an incoming connection. Session key has already
* been exchanged and encryption is enabled.
*/
void
do_authentication(Authctxt *authctxt)
{
u_int ulen;
char *user, *style = NULL;
/* Get the name of the user that we wish to log in as. */
packet_read_expect(SSH_CMSG_USER);
/* Get the user name. */
user = packet_get_cstring(&ulen);
packet_check_eom();
if ((style = strchr(user, ':')) != NULL)
*style++ = '\0';
authctxt->user = user;
authctxt->style = style;
/* Verify that the user is a valid user. */
if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
authctxt->valid = 1;
else {
debug("do_authentication: invalid user %s", user);
authctxt->pw = fakepw();
}
/* Configuration may have changed as a result of Match */
if (options.num_auth_methods != 0)
fatal("AuthenticationMethods is not supported with SSH "
"protocol 1");
setproctitle("%s%s", authctxt->valid ? user : "******",
use_privsep ? " [net]" : "");
#ifdef USE_PAM
if (options.use_pam)
PRIVSEP(start_pam(authctxt));
#endif
/*
* If we are not running as root, the user must have the same uid as
* the server.
*/
#ifndef HAVE_CYGWIN
if (!use_privsep && getuid() != 0 && authctxt->pw &&
authctxt->pw->pw_uid != getuid())
packet_disconnect("Cannot change user when server not running as root.");
#endif
/*
* Loop until the user has been authenticated or the connection is
* closed, do_authloop() returns only if authentication is successful
*/
do_authloop(authctxt);
/* The user has been authenticated and accepted. */
packet_start(SSH_SMSG_SUCCESS);
packet_send();
packet_write_wait();
}
static int
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->valid) {
debug2("userauth_pubkey: disabled because of invalid user");
return 0;
}
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 */
logit("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;
}
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 */
authenticated = 0;
if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
buffer_len(&b))) == 1)
authenticated = 1;
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 (PRIVSEP(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->postponed = 1;
}
}
if (authenticated != 1)
auth_clear_options();
done:
debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
if (key != NULL)
key_free(key);
xfree(pkalg);
xfree(pkblob);
return authenticated;
}
/*
* We only support those mechanisms that we know about (ie ones that we know
* how to check local user kuserok and the like)
*/
static int
userauth_gssapi(Authctxt *authctxt)
{
gss_OID_desc goid = {0, NULL};
Gssctxt *ctxt = NULL;
int mechs;
int present;
OM_uint32 ms;
u_int len;
u_char *doid = NULL;
if (!authctxt->valid || authctxt->user == NULL)
return (0);
mechs = packet_get_int();
if (mechs == 0) {
debug("Mechanism negotiation is not supported");
return (0);
}
do {
mechs--;
free(doid);
present = 0;
doid = packet_get_string(&len);
if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
doid[1] == len - 2) {
goid.elements = doid + 2;
goid.length = len - 2;
ssh_gssapi_test_oid_supported(&ms, &goid, &present);
} else {
logit("Badly formed OID received");
}
} while (mechs > 0 && !present);
if (!present) {
free(doid);
authctxt->server_caused_failure = 1;
return (0);
}
if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
if (ctxt != NULL)
ssh_gssapi_delete_ctx(&ctxt);
free(doid);
authctxt->server_caused_failure = 1;
return (0);
}
authctxt->methoddata = (void *)ctxt;
packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
/* Return the OID that we received */
packet_put_string(doid, len);
packet_send();
free(doid);
dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
authctxt->postponed = 1;
return (0);
}
/*
* Checks if the user has an authentication agent, and if so, tries to
* authenticate using the agent.
*/
static int
try_agent_authentication(void)
{
int type;
char *comment;
AuthenticationConnection *auth;
u_char response[16];
u_int i;
Key *key;
BIGNUM *challenge;
/* Get connection to the agent. */
auth = ssh_get_authentication_connection();
if (!auth)
return 0;
if ((challenge = BN_new()) == NULL)
fatal("try_agent_authentication: BN_new failed");
/* Loop through identities served by the agent. */
for (key = ssh_get_first_identity(auth, &comment, 1);
key != NULL;
key = ssh_get_next_identity(auth, &comment, 1)) {
/* Try this identity. */
debug("Trying RSA authentication via agent with '%.100s'", comment);
xfree(comment);
/* Tell the server that we are willing to authenticate using this key. */
packet_start(SSH_CMSG_AUTH_RSA);
packet_put_bignum(key->rsa->n);
packet_send();
packet_write_wait();
/* Wait for server's response. */
type = packet_read();
/* The server sends failure if it doesn\'t like our key or
does not support RSA authentication. */
if (type == SSH_SMSG_FAILURE) {
debug("Server refused our key.");
key_free(key);
continue;
}
/* Otherwise it should have sent a challenge. */
if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
packet_disconnect("Protocol error during RSA authentication: %d",
type);
packet_get_bignum(challenge);
packet_check_eom();
debug("Received RSA challenge from server.");
/* Ask the agent to decrypt the challenge. */
if (!ssh_decrypt_challenge(auth, key, challenge, session_id, 1, response)) {
/*
* The agent failed to authenticate this identifier
* although it advertised it supports this. Just
* return a wrong value.
*/
log("Authentication agent failed to decrypt challenge.");
memset(response, 0, sizeof(response));
}
key_free(key);
debug("Sending response to RSA challenge.");
/* Send the decrypted challenge back to the server. */
packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
for (i = 0; i < 16; i++)
packet_put_char(response[i]);
packet_send();
packet_write_wait();
/* Wait for response from the server. */
type = packet_read();
/* The server returns success if it accepted the authentication. */
if (type == SSH_SMSG_SUCCESS) {
ssh_close_authentication_connection(auth);
BN_clear_free(challenge);
debug("RSA authentication accepted by server.");
return 1;
}
/* Otherwise it should return failure. */
if (type != SSH_SMSG_FAILURE)
packet_disconnect("Protocol error waiting RSA auth response: %d",
type);
}
ssh_close_authentication_connection(auth);
BN_clear_free(challenge);
debug("RSA authentication using agent refused.");
return 0;
}
static int
server_input_global_request(int type, u_int32_t seq, void *ctxt)
{
char *rtype;
int want_reply;
int r, success = 0, allocated_listen_port = 0;
struct sshbuf *resp = NULL;
rtype = packet_get_string(NULL);
want_reply = packet_get_char();
debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
/* -R style forwarding */
if (strcmp(rtype, "tcpip-forward") == 0) {
struct passwd *pw;
struct Forward fwd;
pw = the_authctxt->pw;
if (pw == NULL || !the_authctxt->valid)
fatal("server_input_global_request: no/invalid user");
memset(&fwd, 0, sizeof(fwd));
fwd.listen_host = packet_get_string(NULL);
fwd.listen_port = (u_short)packet_get_int();
debug("server_input_global_request: tcpip-forward listen %s port %d",
fwd.listen_host, fwd.listen_port);
/* check permissions */
if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
no_port_forwarding_flag ||
(!want_reply && fwd.listen_port == 0)
#ifndef NO_IPPORT_RESERVED_CONCEPT
|| (fwd.listen_port != 0 && fwd.listen_port < IPPORT_RESERVED &&
pw->pw_uid != 0)
#endif
) {
success = 0;
packet_send_debug("Server has disabled port forwarding.");
} else {
/* Start listening on the port */
success = channel_setup_remote_fwd_listener(&fwd,
&allocated_listen_port, &options.fwd_opts);
}
free(fwd.listen_host);
if ((resp = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new", __func__);
if ((r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
struct Forward fwd;
memset(&fwd, 0, sizeof(fwd));
fwd.listen_host = packet_get_string(NULL);
fwd.listen_port = (u_short)packet_get_int();
debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
fwd.listen_host, fwd.listen_port);
success = channel_cancel_rport_listener(&fwd);
free(fwd.listen_host);
} else if (strcmp(rtype, "*****@*****.**") == 0) {
struct Forward fwd;
memset(&fwd, 0, sizeof(fwd));
fwd.listen_path = packet_get_string(NULL);
debug("server_input_global_request: streamlocal-forward listen path %s",
fwd.listen_path);
/* check permissions */
if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
|| no_port_forwarding_flag) {
success = 0;
packet_send_debug("Server has disabled port forwarding.");
} else {
/* Start listening on the socket */
success = channel_setup_remote_fwd_listener(
&fwd, NULL, &options.fwd_opts);
}
free(fwd.listen_path);
} else if (strcmp(rtype, "*****@*****.**") == 0) {
struct Forward fwd;
memset(&fwd, 0, sizeof(fwd));
fwd.listen_path = packet_get_string(NULL);
debug("%s: cancel-streamlocal-forward path %s", __func__,
fwd.listen_path);
success = channel_cancel_rport_listener(&fwd);
free(fwd.listen_path);
} else if (strcmp(rtype, "*****@*****.**") == 0) {
no_more_sessions = 1;
success = 1;
} else if (strcmp(rtype, "*****@*****.**") == 0) {
success = server_input_hostkeys_prove(&resp);
}
if (want_reply) {
packet_start(success ?
SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
if (success && resp != NULL)
ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
sshbuf_len(resp));
packet_send();
packet_write_wait();
}
free(rtype);
sshbuf_free(resp);
return 0;
}
void
kexgss_client(Kex *kex) {
gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr;
Gssctxt *ctxt;
OM_uint32 maj_status, min_status, ret_flags;
u_int klen, kout, slen = 0, hashlen, strlen;
DH *dh;
BIGNUM *dh_server_pub = NULL;
BIGNUM *shared_secret = NULL;
BIGNUM *p = NULL;
BIGNUM *g = NULL;
u_char *kbuf, *hash;
u_char *serverhostkey = NULL;
u_char *empty = "";
char *msg;
char *lang;
int type = 0;
int first = 1;
int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;
/* Initialise our GSSAPI world */
ssh_gssapi_build_ctx(&ctxt);
if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type)
== GSS_C_NO_OID)
fatal("Couldn't identify host exchange");
if (ssh_gssapi_import_name(ctxt, kex->gss_host))
fatal("Couldn't import hostname");
if (kex->gss_client &&
ssh_gssapi_client_identity(ctxt, kex->gss_client))
fatal("Couldn't acquire client credentials");
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
dh = dh_new_group1();
break;
case KEX_GSS_GRP14_SHA1:
dh = dh_new_group14();
break;
case KEX_GSS_GEX_SHA1:
debug("Doing group exchange\n");
nbits = dh_estimate(kex->we_need * 8);
packet_start(SSH2_MSG_KEXGSS_GROUPREQ);
packet_put_int(min);
packet_put_int(nbits);
packet_put_int(max);
packet_send();
packet_read_expect(SSH2_MSG_KEXGSS_GROUP);
if ((p = BN_new()) == NULL)
fatal("BN_new() failed");
packet_get_bignum2(p);
if ((g = BN_new()) == NULL)
fatal("BN_new() failed");
packet_get_bignum2(g);
packet_check_eom();
if (BN_num_bits(p) < min || BN_num_bits(p) > max)
fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
min, BN_num_bits(p), max);
dh = dh_new_group(g, p);
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
/* Step 1 - e is dh->pub_key */
dh_gen_key(dh, kex->we_need * 8);
/* This is f, we initialise it now to make life easier */
dh_server_pub = BN_new();
if (dh_server_pub == NULL)
fatal("dh_server_pub == NULL");
token_ptr = GSS_C_NO_BUFFER;
do {
debug("Calling gss_init_sec_context");
maj_status = ssh_gssapi_init_ctx(ctxt,
kex->gss_deleg_creds, token_ptr, &send_tok,
&ret_flags);
if (GSS_ERROR(maj_status)) {
if (send_tok.length != 0) {
packet_start(SSH2_MSG_KEXGSS_CONTINUE);
packet_put_string(send_tok.value,
send_tok.length);
}
fatal("gss_init_context failed");
}
/* If we've got an old receive buffer get rid of it */
if (token_ptr != GSS_C_NO_BUFFER)
xfree(recv_tok.value);
if (maj_status == GSS_S_COMPLETE) {
/* If mutual state flag is not true, kex fails */
if (!(ret_flags & GSS_C_MUTUAL_FLAG))
fatal("Mutual authentication failed");
/* If integ avail flag is not true kex fails */
if (!(ret_flags & GSS_C_INTEG_FLAG))
fatal("Integrity check failed");
}
/*
* If we have data to send, then the last message that we
* received cannot have been a 'complete'.
*/
if (send_tok.length != 0) {
if (first) {
packet_start(SSH2_MSG_KEXGSS_INIT);
packet_put_string(send_tok.value,
send_tok.length);
packet_put_bignum2(dh->pub_key);
first = 0;
} else {
packet_start(SSH2_MSG_KEXGSS_CONTINUE);
packet_put_string(send_tok.value,
send_tok.length);
}
packet_send();
gss_release_buffer(&min_status, &send_tok);
/* If we've sent them data, they should reply */
do {
type = packet_read();
if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
debug("Received KEXGSS_HOSTKEY");
if (serverhostkey)
fatal("Server host key received more than once");
serverhostkey =
packet_get_string(&slen);
}
} while (type == SSH2_MSG_KEXGSS_HOSTKEY);
switch (type) {
case SSH2_MSG_KEXGSS_CONTINUE:
debug("Received GSSAPI_CONTINUE");
if (maj_status == GSS_S_COMPLETE)
fatal("GSSAPI Continue received from server when complete");
recv_tok.value = packet_get_string(&strlen);
recv_tok.length = strlen;
break;
case SSH2_MSG_KEXGSS_COMPLETE:
debug("Received GSSAPI_COMPLETE");
packet_get_bignum2(dh_server_pub);
msg_tok.value = packet_get_string(&strlen);
msg_tok.length = strlen;
/* Is there a token included? */
if (packet_get_char()) {
recv_tok.value=
packet_get_string(&strlen);
recv_tok.length = strlen;
/* If we're already complete - protocol error */
if (maj_status == GSS_S_COMPLETE)
packet_disconnect("Protocol error: received token when complete");
} else {
/* No token included */
if (maj_status != GSS_S_COMPLETE)
packet_disconnect("Protocol error: did not receive final token");
}
break;
case SSH2_MSG_KEXGSS_ERROR:
debug("Received Error");
maj_status = packet_get_int();
min_status = packet_get_int();
msg = packet_get_string(NULL);
lang = packet_get_string(NULL);
fatal("GSSAPI Error: \n%.400s",msg);
default:
packet_disconnect("Protocol error: didn't expect packet type %d",
type);
}
token_ptr = &recv_tok;
} else {
/* No data, and not complete */
if (maj_status != GSS_S_COMPLETE)
fatal("Not complete, and no token output");
}
} while (maj_status & GSS_S_CONTINUE_NEEDED);
/*
* We _must_ have received a COMPLETE message in reply from the
* server, which will have set dh_server_pub and msg_tok
*/
if (type != SSH2_MSG_KEXGSS_COMPLETE)
fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
/* Check f in range [1, p-1] */
if (!dh_pub_is_valid(dh, dh_server_pub))
packet_disconnect("bad server public DH value");
/* compute K=f^x mod p */
klen = DH_size(dh);
kbuf = xmalloc(klen);
kout = DH_compute_key(kbuf, dh_server_pub, dh);
if (kout < 0)
fatal("DH_compute_key: failed");
shared_secret = BN_new();
if (shared_secret == NULL)
fatal("kexgss_client: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexdh_client: BN_bin2bn failed");
memset(kbuf, 0, klen);
xfree(kbuf);
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
case KEX_GSS_GRP14_SHA1:
kex_dh_hash( kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
(serverhostkey ? serverhostkey : empty), slen,
dh->pub_key, /* e */
dh_server_pub, /* f */
shared_secret, /* K */
&hash, &hashlen
);
break;
case KEX_GSS_GEX_SHA1:
kexgex_hash(
kex->evp_md,
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
(serverhostkey ? serverhostkey : empty), slen,
min, nbits, max,
dh->p, dh->g,
dh->pub_key,
dh_server_pub,
shared_secret,
&hash, &hashlen
);
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
gssbuf.value = hash;
gssbuf.length = hashlen;
/* Verify that the hash matches the MIC we just got. */
if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
packet_disconnect("Hash's MIC didn't verify");
xfree(msg_tok.value);
DH_free(dh);
if (serverhostkey)
xfree(serverhostkey);
BN_clear_free(dh_server_pub);
/* save session id */
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);
}
if (kex->gss_deleg_creds)
ssh_gssapi_credentials_updated(ctxt);
if (gss_kex_context == NULL)
gss_kex_context = ctxt;
else
ssh_gssapi_delete_ctx(&ctxt);
kex_derive_keys(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
static int
userauth_pubkey(Authctxt *authctxt)
{
#ifdef WIN32_FIXME
int loginStat = 1;
char currentUser[MAX_PATH] = {0};
DWORD currentUserSize = sizeof(currentUser);
int targetIsCurrent = 0;
# ifdef USE_NTCREATETOKEN
int doOpenSSHVerify = 1;
# else
int doOpenSSHVerify = 0;
# endif
#endif
Buffer b;
Key *key = NULL;
char *pkalg, *userstyle;
u_char *pkblob, *sig;
u_int alen, blen, slen;
int have_sig, pktype;
int authenticated = 0;
if (!authctxt->valid) {
debug2("userauth_pubkey: disabled because of invalid user");
return 0;
}
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 */
logit("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;
}
if (key_type_plain(key->type) == KEY_RSA &&
(datafellows & SSH_BUG_RSASIGMD5) != 0) {
logit("Refusing RSA key because client uses unsafe "
"signature scheme");
goto done;
}
if (auth2_userkey_already_used(authctxt, key)) {
logit("refusing previously-used %s key", key_type(key));
goto done;
}
if (match_pattern_list(sshkey_ssh_name(key),
options.pubkey_key_types, 0) != 1) {
logit("%s: key type %s not in PubkeyAcceptedKeyTypes",
__func__, sshkey_ssh_name(key));
goto done;
}
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);
xasprintf(&userstyle, "%s%s%s", authctxt->user,
authctxt->style ? ":" : "",
authctxt->style ? authctxt->style : "");
buffer_put_cstring(&b, userstyle);
free(userstyle);
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
pubkey_auth_info(authctxt, key, NULL);
/* test for correct signature */
authenticated = 0;
/*
* On pure win32 try to logon using lsa first.
*/
#ifdef WIN32_FIXME
authctxt -> hTokenLsa_ = NULL;
authctxt -> methoddata = NULL;
/*
* Retrieve name of current login user (i.e. sshd process owner).
*/
GetUserName(currentUser, ¤tUserSize);
/*
* Try to get token from lsa, but only if targetUser != currentUser.
* Owerthise we already have targetUser's token in current thread, so
* we only need key verify from original OpenSSH code.
*/
targetIsCurrent = (strcmp(currentUser, authctxt -> user) == 0);
if (targetIsCurrent)
{
doOpenSSHVerify = 1;
}
else
{
loginStat = LsaLogon(&authctxt -> hTokenLsa_, HomeDirLsaW,
authctxt -> user, pkblob, blen, sig, slen,
buffer_ptr(&b), buffer_len(&b), datafellows);
/*
* If lsa logon process success.
*/
if (loginStat == 0)
{
/*
* And user authorized OK.
*/
if (authctxt -> hTokenLsa_)
{
doOpenSSHVerify = 0;
/*
* This is part of openssh authorization needed for parsing
* 'options' block in key.
*/
authctxt -> pw -> pw_dir = GetHomeDir(authctxt -> user);
if (PRIVSEP(user_key_allowed(authctxt -> pw, key, 1))) // PRAGMA:TODO
{
authenticated = 1;
}
else
{
authenticated = 0;
}
buffer_free(&b);
free(sig);
}
}
}
if (doOpenSSHVerify)
{
/*
* If lsa fails, test for correct signature using openssh code.
*/
authctxt -> pw -> pw_dir = GetHomeDir(authctxt -> user);
if (PRIVSEP(user_key_allowed(authctxt->pw, key, 0)) //PRAGMA:TODO
&&
PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b))) == 1)
{
authenticated = 1;
}
}
/*
* Original code.
*/
#else /* #ifdef WIN32_FIXME */
if (PRIVSEP(user_key_allowed(authctxt->pw, key, 1)) &&
PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
buffer_len(&b))) == 1) {
authenticated = 1;
/* Record the successful key to prevent reuse */
auth2_record_userkey(authctxt, key);
key = NULL; /* Don't free below */
}
buffer_free(&b);
free(sig);
#endif /* else #ifdef WIN32_FIXME. */
} 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
*/
#ifndef WIN32_FIXME
if (PRIVSEP(user_key_allowed(authctxt->pw, key, 0)))
#endif
{
packet_start(SSH2_MSG_USERAUTH_PK_OK);
packet_put_string(pkalg, alen);
packet_put_string(pkblob, blen);
packet_send();
packet_write_wait();
authctxt->postponed = 1;
}
}
if (authenticated != 1)
auth_clear_options();
done:
debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
if (key != NULL)
key_free(key);
free(pkalg);
free(pkblob);
return authenticated;
}
/*
* We only support those mechanisms that we know about (ie ones that we know
* how to check local user kuserok and the like
*/
static int
userauth_gssapi(Authctxt *authctxt)
{
gss_OID_desc oid = {0, NULL};
Gssctxt *ctxt = NULL;
int mechs;
gss_OID_set supported;
int present;
OM_uint32 ms;
u_int len;
char *doid = NULL;
if (!authctxt->valid || authctxt->user == NULL)
return (0);
mechs = packet_get_int();
if (mechs == 0) {
debug("Mechanism negotiation is not supported");
return (0);
}
ssh_gssapi_supported_oids(&supported);
do {
mechs--;
if (doid)
xfree(doid);
doid = packet_get_string(&len);
if (doid[0] != SSH_GSS_OIDTYPE || doid[1] != len-2) {
logit("Mechanism OID received using the old encoding form");
oid.elements = doid;
oid.length = len;
} else {
oid.elements = doid + 2;
oid.length = len - 2;
}
gss_test_oid_set_member(&ms, &oid, supported, &present);
} while (mechs > 0 && !present);
gss_release_oid_set(&ms, &supported);
if (!present) {
xfree(doid);
return (0);
}
if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) {
xfree(doid);
return (0);
}
authctxt->methoddata=(void *)ctxt;
packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
/* Return OID in same format as we received it*/
packet_put_string(doid, len);
packet_send();
xfree(doid);
dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
authctxt->postponed = 1;
return (0);
}
/*
* read packets, try to authenticate the user and
* return only if authentication is successful
*/
static void
do_authloop(Authctxt *authctxt)
{
int authenticated = 0;
u_int bits;
Key *client_host_key;
BIGNUM *n;
char *client_user, *password;
char info[1024];
u_int dlen;
u_int ulen;
int type = 0;
struct passwd *pw = authctxt->pw;
debug("Attempting authentication for %s%.100s.",
authctxt->valid ? "" : "illegal user ", authctxt->user);
/* If the user has no password, accept authentication immediately. */
if (options.password_authentication &&
#if defined(KRB4) || defined(KRB5)
(!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
PRIVSEP(auth_password(authctxt, ""))) {
auth_log(authctxt, 1, "without authentication", "");
return;
}
/* Indicate that authentication is needed. */
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
client_user = NULL;
for ( ;; ) {
/* default to fail */
authenticated = 0;
info[0] = '\0';
/* Get a packet from the client. */
authctxt->v1_auth_type = type = packet_read();
authctxt->v1_auth_name = get_authname(type);
authctxt->attempt++;
/* Process the packet. */
switch (type) {
#if defined(KRB4) || defined(KRB5)
case SSH_CMSG_AUTH_KERBEROS:
if (!options.kerberos_authentication) {
verbose("Kerberos authentication disabled.");
} else {
char *kdata = packet_get_string(&dlen);
packet_check_eom();
if (kdata[0] == 4) { /* KRB_PROT_VERSION */
#ifdef KRB4
KTEXT_ST tkt, reply;
tkt.length = dlen;
if (tkt.length < MAX_KTXT_LEN)
memcpy(tkt.dat, kdata, tkt.length);
if (PRIVSEP(auth_krb4(authctxt, &tkt,
&client_user, &reply))) {
authenticated = 1;
snprintf(info, sizeof(info),
" tktuser %.100s",
client_user);
packet_start(
SSH_SMSG_AUTH_KERBEROS_RESPONSE);
packet_put_string((char *)
reply.dat, reply.length);
packet_send();
packet_write_wait();
}
#endif /* KRB4 */
} else {
#ifdef KRB5
krb5_data tkt, reply;
tkt.length = dlen;
tkt.data = kdata;
if (PRIVSEP(auth_krb5(authctxt, &tkt,
&client_user, &reply))) {
authenticated = 1;
snprintf(info, sizeof(info),
" tktuser %.100s",
client_user);
/* Send response to client */
packet_start(
SSH_SMSG_AUTH_KERBEROS_RESPONSE);
packet_put_string((char *)
reply.data, reply.length);
packet_send();
packet_write_wait();
if (reply.length)
xfree(reply.data);
}
#endif /* KRB5 */
}
xfree(kdata);
}
break;
#endif /* KRB4 || KRB5 */
#if defined(AFS) || defined(KRB5)
/* XXX - punt on backward compatibility here. */
case SSH_CMSG_HAVE_KERBEROS_TGT:
packet_send_debug("Kerberos TGT passing disabled before authentication.");
break;
#ifdef AFS
case SSH_CMSG_HAVE_AFS_TOKEN:
packet_send_debug("AFS token passing disabled before authentication.");
break;
#endif /* AFS */
#endif /* AFS || KRB5 */
case SSH_CMSG_AUTH_RHOSTS:
if (!options.rhosts_authentication) {
verbose("Rhosts authentication disabled.");
break;
}
/*
* Get client user name. Note that we just have to
* trust the client; this is one reason why rhosts
* authentication is insecure. (Another is
* IP-spoofing on a local network.)
*/
client_user = packet_get_string(&ulen);
packet_check_eom();
/* Try to authenticate using /etc/hosts.equiv and .rhosts. */
authenticated = auth_rhosts(pw, client_user);
snprintf(info, sizeof info, " ruser %.100s", client_user);
break;
case SSH_CMSG_AUTH_RHOSTS_RSA:
if (!options.rhosts_rsa_authentication) {
verbose("Rhosts with RSA authentication disabled.");
break;
}
/*
* Get client user name. Note that we just have to
* trust the client; root on the client machine can
* claim to be any user.
*/
client_user = packet_get_string(&ulen);
/* Get the client host key. */
client_host_key = key_new(KEY_RSA1);
bits = packet_get_int();
packet_get_bignum(client_host_key->rsa->e);
packet_get_bignum(client_host_key->rsa->n);
if (bits != BN_num_bits(client_host_key->rsa->n))
verbose("Warning: keysize mismatch for client_host_key: "
"actual %d, announced %d",
BN_num_bits(client_host_key->rsa->n), bits);
packet_check_eom();
authenticated = auth_rhosts_rsa(pw, client_user,
client_host_key);
key_free(client_host_key);
snprintf(info, sizeof info, " ruser %.100s", client_user);
break;
case SSH_CMSG_AUTH_RSA:
if (!options.rsa_authentication) {
verbose("RSA authentication disabled.");
break;
}
/* RSA authentication requested. */
if ((n = BN_new()) == NULL)
fatal("do_authloop: BN_new failed");
packet_get_bignum(n);
packet_check_eom();
authenticated = auth_rsa(pw, n);
BN_clear_free(n);
break;
case SSH_CMSG_AUTH_PASSWORD:
authctxt->init_attempt++;
if (!options.password_authentication) {
verbose("Password authentication disabled.");
break;
}
/*
* Read user password. It is in plain text, but was
* transmitted over the encrypted channel so it is
* not visible to an outside observer.
*/
password = packet_get_string(&dlen);
packet_check_eom();
/* Try authentication with the password. */
if (authctxt->init_failures <
options.max_init_auth_tries)
authenticated =
PRIVSEP(auth_password(authctxt,
password));
memset(password, 0, strlen(password));
xfree(password);
break;
case SSH_CMSG_AUTH_TIS:
debug("rcvd SSH_CMSG_AUTH_TIS");
if (options.challenge_response_authentication == 1) {
char *challenge = get_challenge(authctxt);
if (challenge != NULL) {
debug("sending challenge '%s'", challenge);
packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
packet_put_cstring(challenge);
xfree(challenge);
packet_send();
packet_write_wait();
continue;
}
}
break;
case SSH_CMSG_AUTH_TIS_RESPONSE:
debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
if (options.challenge_response_authentication == 1) {
char *response = packet_get_string(&dlen);
debug("got response '%s'", response);
packet_check_eom();
authenticated = verify_response(authctxt, response);
memset(response, 'r', dlen);
xfree(response);
}
break;
default:
/*
* Any unknown messages will be ignored (and failure
* returned) during authentication.
*/
log("Unknown message during authentication: type %d", type);
break;
}
#ifdef BSD_AUTH
if (authctxt->as) {
auth_close(authctxt->as);
authctxt->as = NULL;
}
#endif
if (!authctxt->valid && authenticated) {
authenticated = 0;
log("Ignoring authenticated invalid user %s",
authctxt->user);
}
#ifdef _UNICOS
if (type == SSH_CMSG_AUTH_PASSWORD && !authenticated)
cray_login_failure(authctxt->user, IA_UDBERR);
if (authenticated && cray_access_denied(authctxt->user)) {
authenticated = 0;
fatal("Access denied for user %s.",authctxt->user);
}
#endif /* _UNICOS */
#ifdef HAVE_CYGWIN
if (authenticated &&
!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) {
packet_disconnect("Authentication rejected for uid %d.",
pw == NULL ? -1 : pw->pw_uid);
authenticated = 0;
}
#else
/* Special handling for root */
if (!use_privsep &&
authenticated && authctxt->pw->pw_uid == 0 &&
!auth_root_allowed(get_authname(type)))
authenticated = 0;
#endif
#ifdef USE_PAM
/* XXX PAM and PRIVSEP don't mix */
if (use_privsep && authenticated)
fatal("Privsep is not supported");
if (authenticated && type != SSH_CMSG_AUTH_PASSWORD)
authenticated = do_pam_non_initial_userauth(authctxt);
else if (authenticated && !AUTHPAM_DONE(authctxt))
authenticated = 0;
if (!authenticated)
authctxt->pam_retval = AUTHPAM_ERROR(authctxt,
PAM_PERM_DENIED);
#endif /* USE_PAM */
/* Log before sending the reply */
auth_log(authctxt, authenticated, get_authname(type), info);
if (client_user != NULL) {
xfree(client_user);
client_user = NULL;
}
if (authenticated)
return;
if (type == SSH_CMSG_AUTH_PASSWORD)
authctxt->init_failures++;
if (authctxt->failures++ > options.max_auth_tries) {
#ifdef HAVE_BSM
fatal_remove_cleanup(audit_failed_login_cleanup,
authctxt);
audit_sshd_login_failure(&ah, PAM_MAXTRIES);
#endif /* HAVE_BSM */
packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
}
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
}
}
/*
* Performs authentication of an incoming connection. Session key has already
* been exchanged and encryption is enabled.
*/
Authctxt *
do_authentication(void)
{
Authctxt *authctxt;
u_int ulen;
char *user, *style = NULL;
/* Get the name of the user that we wish to log in as. */
packet_read_expect(SSH_CMSG_USER);
/* Get the user name. */
user = packet_get_string(&ulen);
packet_check_eom();
if ((style = strchr(user, ':')) != NULL)
*style++ = '\0';
#ifdef KRB5
/* XXX - SSH.com Kerberos v5 braindeath. */
if ((datafellows & SSH_BUG_K5USER) &&
options.kerberos_authentication) {
char *p;
if ((p = strchr(user, '@')) != NULL)
*p = '\0';
}
#endif
authctxt = authctxt_new();
authctxt->user = user;
authctxt->style = style;
#ifdef HAVE_BSM
fatal_add_cleanup(audit_failed_login_cleanup, authctxt);
#endif /* HAVE_BSM */
/* Verify that the user is a valid user. */
if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL) {
authctxt->valid = 1;
} else {
authctxt->valid = 0;
debug("do_authentication: illegal user %s", user);
}
setproctitle("%s%s", authctxt->pw ? user : "******",
use_privsep ? " [net]" : "");
#if 0
#ifdef USE_PAM
PRIVSEP(start_pam(authctxt->pw == NULL ? "NOUSER" : user));
#endif
#endif
/*
* If we are not running as root, the user must have the same uid as
* the server. (Unless you are running Windows)
*/
#ifndef HAVE_CYGWIN
if (!use_privsep && getuid() != 0 && authctxt->pw &&
authctxt->pw->pw_uid != getuid())
packet_disconnect("Cannot change user when server not running as root.");
#endif
/*
* Loop until the user has been authenticated or the connection is
* closed, do_authloop() returns only if authentication is successful
*/
do_authloop(authctxt);
/* The user has been authenticated and accepted. */
packet_start(SSH_SMSG_SUCCESS);
packet_send();
packet_write_wait();
return (authctxt);
}
/*
* parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
*/
void
input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
{
Authctxt *authctxt = ctxt;
char *info, *lang, *password = NULL, *retype = NULL;
char prompt[150];
debug2("input_userauth_passwd_changereq");
if (authctxt == NULL)
fatal("input_userauth_passwd_changereq: "
"no authentication context");
info = packet_get_utf8_string(NULL);
if (strlen(info) != 0) {
info = g11n_filter_string(info);
log("%s", info);
}
xfree(info);
lang = packet_get_string(NULL);
xfree(lang);
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(1); /* additional info */
snprintf(prompt, sizeof(prompt),
gettext("Enter %.30s@%.128s's old password: "******"Enter %.30s@%.128s's new password: "******"Retype %.30s@%.128s's new password: "******"Mismatch; try again, EOF to quit.");
password = NULL;
}
memset(retype, 0, strlen(retype));
xfree(retype);
}
packet_put_cstring(password);
memset(password, 0, strlen(password));
xfree(password);
packet_add_padding(64);
packet_send();
dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
&input_userauth_passwd_changereq);
}
struct packet *new_tcp_packet(int socket_fd,
int address_family,
enum direction_t direction,
enum ip_ecn_t ecn,
const char *flags,
u32 start_sequence,
u16 tcp_payload_bytes,
u32 ack_sequence,
s32 window,
const struct tcp_options *tcp_options,
char **error)
{
struct packet *packet = NULL; /* the newly-allocated result packet */
/* Calculate lengths in bytes of all sections of the packet */
const int ip_option_bytes = 0;
const int tcp_option_bytes = tcp_options ? tcp_options->length : 0;
const int ip_header_bytes = (ip_header_len(address_family) +
ip_option_bytes);
const int tcp_header_bytes = sizeof(struct tcp) + tcp_option_bytes;
const int ip_bytes =
ip_header_bytes + tcp_header_bytes + tcp_payload_bytes;
/* Sanity-check all the various lengths */
if (ip_option_bytes & 0x3) {
asprintf(error, "IP options are not padded correctly "
"to ensure IP header is a multiple of 4 bytes: "
"%d excess bytes", ip_option_bytes & 0x3);
printf("1\n");
return NULL;
}
if (tcp_option_bytes & 0x3) {
asprintf(error,
"TCP options are not padded correctly "
"to ensure TCP header is a multiple of 4 bytes: "
"%d excess bytes", tcp_option_bytes & 0x3);
printf("2\n");
return NULL;
}
assert((tcp_header_bytes & 0x3) == 0);
assert((ip_header_bytes & 0x3) == 0);
if (tcp_header_bytes > MAX_TCP_HEADER_BYTES) {
asprintf(error, "TCP header too large");
return NULL;
}
if (ip_bytes > MAX_TCP_DATAGRAM_BYTES) {
asprintf(error, "TCP segment too large");
return NULL;
}
if (!is_tcp_flags_spec_valid(flags, error)){
return NULL;
}
/* Allocate and zero out a packet object of the desired size */
packet = packet_new(ip_bytes);
memset(packet->buffer, 0, ip_bytes);
packet->ip_bytes = ip_bytes;
packet->direction = direction;
packet->socket_script_fd = socket_fd;
packet->flags = 0;
packet->ecn = ecn;
/* Set IP header fields */
set_packet_ip_header(packet, address_family, ip_bytes, direction, ecn,
IPPROTO_TCP);
/* Find the start of TCP sections of the packet */
packet->tcp = (struct tcp *) (packet_start(packet) + ip_header_bytes);
u8 *tcp_option_start = (u8 *) (packet->tcp + 1);
/* Set TCP header fields */
packet->tcp->src_port = htons(0);
packet->tcp->dst_port = htons(0);
packet->tcp->seq = htonl(start_sequence);
packet->tcp->ack_seq = htonl(ack_sequence);
packet->tcp->doff = tcp_header_bytes / 4;
if (window == -1) {
if (direction == DIRECTION_INBOUND) {
asprintf(error, "window must be specified"
" for inbound packets");
return NULL;
}
packet->tcp->window = 0;
packet->flags |= FLAG_WIN_NOCHECK;
} else {
packet->tcp->window = htons(window);
}
packet->tcp->check = 0;
packet->tcp->urg_ptr = 0;
packet->tcp->fin = is_tcp_flag_set('F', flags);
packet->tcp->syn = is_tcp_flag_set('S', flags);
packet->tcp->rst = is_tcp_flag_set('R', flags);
packet->tcp->psh = is_tcp_flag_set('P', flags);
packet->tcp->ack = is_tcp_flag_set('.', flags);
packet->tcp->urg = 0;
packet->tcp->ece = is_tcp_flag_set('E', flags);
packet->tcp->cwr = is_tcp_flag_set('W', flags);
if (tcp_options == NULL) {
packet->flags |= FLAG_OPTIONS_NOCHECK;
} else if (tcp_options->length > 0) {
/* Copy TCP options into packet */
memcpy(tcp_option_start, tcp_options->data,
tcp_options->length);
}
return packet;
}
/*
* read packets, try to authenticate the user and
* return only if authentication is successful
*/
static void
do_authloop(Authctxt *authctxt)
{
int authenticated = 0;
int type = 0;
const struct AuthMethod1 *meth;
debug("Attempting authentication for %s%.100s.",
authctxt->valid ? "" : "invalid user ", authctxt->user);
/* If the user has no password, accept authentication immediately. */
if (options.permit_empty_passwd && options.password_authentication &&
#if defined(KRB4) || defined(KRB5)
(!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
PRIVSEP(auth_password(authctxt, __UNCONST("")))) {
#ifdef USE_PAM
if (options.use_pam && PRIVSEP(do_pam_account()))
#endif
{
auth_log(authctxt, 1, 0, "without authentication",
NULL);
return;
}
return;
}
/* Indicate that authentication is needed. */
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
for (;;) {
/* default to fail */
authenticated = 0;
/* Get a packet from the client. */
type = packet_read();
if (authctxt->failures >= options.max_authtries)
goto skip;
if ((meth = lookup_authmethod1(type)) == NULL) {
logit("Unknown message during authentication: "
"type %d", type);
goto skip;
}
if (!*(meth->enabled)) {
verbose("%s authentication disabled.", meth->name);
goto skip;
}
authenticated = meth->method(authctxt);
if (authenticated == -1)
continue; /* "postponed" */
#ifdef BSD_AUTH
if (authctxt->as) {
auth_close(authctxt->as);
authctxt->as = NULL;
}
#endif
if (!authctxt->valid && authenticated)
fatal("INTERNAL ERROR: authenticated invalid user %s",
authctxt->user);
/* Special handling for root */
if (authenticated && authctxt->pw->pw_uid == 0 &&
!auth_root_allowed(meth->name))
authenticated = 0;
#ifdef USE_PAM
if (options.use_pam && authenticated &&
!PRIVSEP(do_pam_account())) {
char *msg;
size_t len;
error("Access denied for user %s by PAM account "
"configuration", authctxt->user);
len = buffer_len(&loginmsg);
buffer_append(&loginmsg, "\0", 1);
msg = (char *)buffer_ptr(&loginmsg);
/* strip trailing newlines */
if (len > 0)
while (len > 0 && msg[--len] == '\n')
msg[len] = '\0';
else
msg = __UNCONST("Access denied.");
packet_disconnect("%s", msg);
}
#endif
skip:
/* Log before sending the reply */
auth_log(authctxt, authenticated, 0, get_authname(type), NULL);
if (authenticated)
return;
if (++authctxt->failures >= options.max_authtries)
auth_maxtries_exceeded(authctxt);
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
}
}
/* process the characters one by one */
static int
process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
{
char string[1024];
pid_t pid;
int bytes = 0;
u_int i;
u_char ch;
char *s;
for (i = 0; i < len; i++) {
/* Get one character at a time. */
ch = buf[i];
if (escape_pending) {
/* We have previously seen an escape character. */
/* Clear the flag now. */
escape_pending = 0;
/* Process the escaped character. */
switch (ch) {
case '.':
/* Terminate the connection. */
snprintf(string, sizeof string, "%c.\r\n", escape_char);
buffer_append(berr, string, strlen(string));
quit_pending = 1;
return -1;
case 'Z' - 64:
/* Suspend the program. */
/* Print a message to that effect to the user. */
snprintf(string, sizeof string, "%c^Z [suspend ssh]\r\n", escape_char);
buffer_append(berr, string, strlen(string));
/* Restore terminal modes and suspend. */
client_suspend_self(bin, bout, berr);
/* We have been continued. */
continue;
case 'B':
if (compat20) {
snprintf(string, sizeof string,
"%cB\r\n", escape_char);
buffer_append(berr, string,
strlen(string));
channel_request_start(session_ident,
"break", 0);
packet_put_int(1000);
packet_send();
}
continue;
case 'R':
if (compat20) {
if (datafellows & SSH_BUG_NOREKEY)
logit("Server does not support re-keying");
else
need_rekeying = 1;
}
continue;
case '&':
/*
* Detach the program (continue to serve connections,
* but put in background and no more new connections).
*/
/* Restore tty modes. */
leave_raw_mode();
/* Stop listening for new connections. */
channel_stop_listening();
snprintf(string, sizeof string,
"%c& [backgrounded]\n", escape_char);
buffer_append(berr, string, strlen(string));
/* Fork into background. */
pid = fork();
if (pid < 0) {
error("fork: %.100s", strerror(errno));
continue;
}
if (pid != 0) { /* This is the parent. */
/* The parent just exits. */
exit(0);
}
/* The child continues serving connections. */
if (compat20) {
buffer_append(bin, "\004", 1);
/* fake EOF on stdin */
return -1;
} else if (!stdin_eof) {
/*
* Sending SSH_CMSG_EOF alone does not always appear
* to be enough. So we try to send an EOF character
* first.
*/
packet_start(SSH_CMSG_STDIN_DATA);
packet_put_string("\004", 1);
packet_send();
/* Close stdin. */
stdin_eof = 1;
if (buffer_len(bin) == 0) {
packet_start(SSH_CMSG_EOF);
packet_send();
}
}
continue;
case '?':
snprintf(string, sizeof string,
"%c?\r\n\
Supported escape sequences:\r\n\
%c. - terminate connection\r\n\
%cB - send a BREAK to the remote system\r\n\
%cC - open a command line\r\n\
%cR - Request rekey (SSH protocol 2 only)\r\n\
%c^Z - suspend ssh\r\n\
%c# - list forwarded connections\r\n\
%c& - background ssh (when waiting for connections to terminate)\r\n\
%c? - this message\r\n\
%c%c - send the escape character by typing it twice\r\n\
(Note that escapes are only recognized immediately after newline.)\r\n",
escape_char, escape_char, escape_char, escape_char,
escape_char, escape_char, escape_char, escape_char,
escape_char, escape_char, escape_char);
buffer_append(berr, string, strlen(string));
continue;
case '#':
snprintf(string, sizeof string, "%c#\r\n", escape_char);
buffer_append(berr, string, strlen(string));
s = channel_open_message();
buffer_append(berr, s, strlen(s));
xfree(s);
continue;
case 'C':
process_cmdline();
continue;
default:
if (ch != escape_char) {
buffer_put_char(bin, escape_char);
bytes++;
}
/* Escaped characters fall through here */
break;
}
} else {
/*
* The previous character was not an escape char. Check if this
* is an escape.
*/
if (last_was_cr && ch == escape_char) {
/* It is. Set the flag and continue to next character. */
escape_pending = 1;
continue;
}
}
/*
* Normal character. Record whether it was a newline,
* and append it to the buffer.
*/
last_was_cr = (ch == '\r' || ch == '\n');
buffer_put_char(bin, ch);
bytes++;
}
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);
}
void
userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
const char *submethod)
{
char *methods;
int partial = 0;
if (!authctxt->valid && authenticated)
fatal("INTERNAL ERROR: authenticated invalid user %s",
authctxt->user);
if (authenticated && authctxt->postponed)
fatal("INTERNAL ERROR: authenticated and postponed");
/* Special handling for root */
if (authenticated && authctxt->pw->pw_uid == 0 &&
!auth_root_allowed(method)) {
authenticated = 0;
#ifdef SSH_AUDIT_EVENTS
PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
#endif
}
if (authenticated && options.num_auth_methods != 0) {
if (!auth2_update_methods_lists(authctxt, method, submethod)) {
authenticated = 0;
partial = 1;
}
}
/* Log before sending the reply */
auth_log(authctxt, authenticated, partial, method, submethod);
if (authctxt->postponed)
return;
#ifdef USE_PAM
if (options.use_pam && authenticated) {
if (!PRIVSEP(do_pam_account())) {
/* if PAM returned a message, send it to the user */
if (buffer_len(&loginmsg) > 0) {
buffer_append(&loginmsg, "\0", 1);
userauth_send_banner(buffer_ptr(&loginmsg));
packet_write_wait();
}
fatal("Access denied for user %s by PAM account "
"configuration", authctxt->user);
}
}
#endif
#ifdef _UNICOS
if (authenticated && cray_access_denied(authctxt->user)) {
authenticated = 0;
fatal("Access denied for user %s.", authctxt->user);
}
#endif /* _UNICOS */
if (authenticated == 1) {
/* turn off userauth */
dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
packet_start(SSH2_MSG_USERAUTH_SUCCESS);
packet_send();
packet_write_wait();
/* now we can break out */
authctxt->success = 1;
} else {
/* Allow initial try of "none" auth without failure penalty */
if (!authctxt->server_caused_failure &&
(authctxt->attempt > 1 || strcmp(method, "none") != 0))
authctxt->failures++;
if (authctxt->failures >= options.max_authtries) {
#ifdef SSH_AUDIT_EVENTS
PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
#endif
packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
}
methods = authmethods_get(authctxt);
debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
partial, methods);
packet_start(SSH2_MSG_USERAUTH_FAILURE);
packet_put_cstring(methods);
packet_put_char(partial);
packet_send();
packet_write_wait();
free(methods);
}
}
static int
userauth_pubkey(Authctxt *authctxt)
{
Buffer b;
Key *key = NULL;
char *pkalg, *userstyle;
u_char *pkblob, *sig;
u_int alen, blen, slen;
int have_sig, pktype;
int authenticated = 0;
if (!authctxt->valid) {
debug2("userauth_pubkey: disabled because of invalid user");
return 0;
}
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 */
logit("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;
}
if (key_type_plain(key->type) == KEY_RSA &&
(datafellows & SSH_BUG_RSASIGMD5) != 0) {
logit("Refusing RSA key because client uses unsafe "
"signature scheme");
goto done;
}
if (auth2_userkey_already_used(authctxt, key)) {
logit("refusing previously-used %s key", key_type(key));
goto done;
}
if (match_pattern_list(sshkey_ssh_name(key), options.pubkey_key_types,
strlen(options.pubkey_key_types), 0) != 1) {
logit("%s: key type %s not in PubkeyAcceptedKeyTypes",
__func__, sshkey_ssh_name(key));
goto done;
}
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);
xasprintf(&userstyle, "%s%s%s", authctxt->user,
authctxt->style ? ":" : "",
authctxt->style ? authctxt->style : "");
buffer_put_cstring(&b, userstyle);
free(userstyle);
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
pubkey_auth_info(authctxt, key, NULL);
/* test for correct signature */
authenticated = 0;
if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
buffer_len(&b))) == 1) {
authenticated = 1;
/* Record the successful key to prevent reuse */
auth2_record_userkey(authctxt, key);
key = NULL; /* Don't free below */
}
buffer_free(&b);
free(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 (PRIVSEP(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->postponed = 1;
}
}
if (authenticated != 1)
auth_clear_options();
done:
debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
if (key != NULL)
key_free(key);
free(pkalg);
free(pkblob);
return authenticated;
}
/*
* read packets, try to authenticate the user and
* return only if authentication is successful
*/
static void
do_authloop(Authctxt *authctxt)
{
int authenticated = 0;
int prev = 0, type = 0;
const struct AuthMethod1 *meth;
debug("Attempting authentication for %s%.100s.",
authctxt->valid ? "" : "invalid user ", authctxt->user);
/* If the user has no password, accept authentication immediately. */
if (options.permit_empty_passwd && options.password_authentication &&
#ifdef KRB5
(!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
PRIVSEP(auth_password(authctxt, ""))) {
#ifdef USE_PAM
if (options.use_pam && (PRIVSEP(do_pam_account())))
#endif
{
auth_log(authctxt, 1, 0, "without authentication",
NULL);
return;
}
}
/* Indicate that authentication is needed. */
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
for (;;) {
/* default to fail */
authenticated = 0;
/* Get a packet from the client. */
prev = type;
type = packet_read();
/*
* If we started challenge-response authentication but the
* next packet is not a response to our challenge, release
* the resources allocated by get_challenge() (which would
* normally have been released by verify_response() had we
* received such a response)
*/
if (prev == SSH_CMSG_AUTH_TIS &&
type != SSH_CMSG_AUTH_TIS_RESPONSE)
abandon_challenge_response(authctxt);
if (authctxt->failures >= options.max_authtries)
goto skip;
if ((meth = lookup_authmethod1(type)) == NULL) {
logit("Unknown message during authentication: "
"type %d", type);
goto skip;
}
if (!*(meth->enabled)) {
verbose("%s authentication disabled.", meth->name);
goto skip;
}
authenticated = meth->method(authctxt);
if (authenticated == -1)
continue; /* "postponed" */
#ifdef BSD_AUTH
if (authctxt->as) {
auth_close(authctxt->as);
authctxt->as = NULL;
}
#endif
if (!authctxt->valid && authenticated)
fatal("INTERNAL ERROR: authenticated invalid user %s",
authctxt->user);
#ifdef _UNICOS
if (authenticated && cray_access_denied(authctxt->user)) {
authenticated = 0;
fatal("Access denied for user %s.",authctxt->user);
}
#endif /* _UNICOS */
#ifndef HAVE_CYGWIN
/* Special handling for root */
if (authenticated && authctxt->pw->pw_uid == 0 &&
!auth_root_allowed(meth->name)) {
authenticated = 0;
# ifdef SSH_AUDIT_EVENTS
PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
# endif
}
#endif
#ifdef USE_PAM
if (options.use_pam && authenticated &&
!PRIVSEP(do_pam_account())) {
char *msg;
size_t len;
error("Access denied for user %s by PAM account "
"configuration", authctxt->user);
len = buffer_len(&loginmsg);
buffer_append(&loginmsg, "\0", 1);
msg = buffer_ptr(&loginmsg);
/* strip trailing newlines */
if (len > 0)
while (len > 0 && msg[--len] == '\n')
msg[len] = '\0';
else
msg = "Access denied.";
packet_disconnect("%s", msg);
}
#endif
skip:
/* Log before sending the reply */
auth_log(authctxt, authenticated, 0, get_authname(type), NULL);
free(client_user);
client_user = NULL;
if (authenticated)
return;
if (++authctxt->failures >= options.max_authtries) {
#ifdef SSH_AUDIT_EVENTS
PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
#endif
packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
}
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
}
}
void
kexecdh_client(Kex *kex)
{
EC_KEY *client_key;
EC_POINT *server_public;
const EC_GROUP *group;
BIGNUM *shared_secret;
Key *server_host_key;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *kbuf, *hash;
u_int klen, slen, sbloblen, hashlen;
if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL)
fatal("%s: EC_KEY_new_by_curve_name failed", __func__);
if (EC_KEY_generate_key(client_key) != 1)
fatal("%s: EC_KEY_generate_key failed", __func__);
group = EC_KEY_get0_group(client_key);
packet_start(SSH2_MSG_KEX_ECDH_INIT);
packet_put_ecpoint(group, EC_KEY_get0_public_key(client_key));
packet_send();
debug("sending SSH2_MSG_KEX_ECDH_INIT");
#ifdef DEBUG_KEXECDH
fputs("client private key:\n", stderr);
key_dump_ec_key(client_key);
#endif
debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY);
/* hostkey */
server_host_key_blob = packet_get_string(&sbloblen);
server_host_key = key_from_blob(server_host_key_blob, sbloblen);
if (server_host_key == NULL)
fatal("cannot decode server_host_key_blob");
if (server_host_key->type != kex->hostkey_type)
fatal("type mismatch for decoded server_host_key_blob");
if (kex->verify_host_key == NULL)
fatal("cannot verify server_host_key");
if (kex->verify_host_key(server_host_key) == -1)
fatal("server_host_key verification failed");
/* Q_S, server public key */
if ((server_public = EC_POINT_new(group)) == NULL)
fatal("%s: EC_POINT_new failed", __func__);
packet_get_ecpoint(group, server_public);
if (key_ec_validate_public(group, server_public) != 0)
fatal("%s: invalid server public key", __func__);
#ifdef DEBUG_KEXECDH
fputs("server public key:\n", stderr);
key_dump_ec_point(group, server_public);
#endif
/* signed H */
signature = packet_get_string(&slen);
packet_check_eom();
klen = (EC_GROUP_get_degree(group) + 7) / 8;
kbuf = xmalloc(klen);
if (ECDH_compute_key(kbuf, klen, server_public,
client_key, NULL) != (int)klen)
fatal("%s: ECDH_compute_key failed", __func__);
#ifdef DEBUG_KEXECDH
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);
free(kbuf);
/* calc and verify H */
kex_ecdh_hash(
kex->evp_md,
group,
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
server_host_key_blob, sbloblen,
EC_KEY_get0_public_key(client_key),
server_public,
shared_secret,
&hash, &hashlen
);
free(server_host_key_blob);
EC_POINT_clear_free(server_public);
EC_KEY_free(client_key);
if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
fatal("key_verify failed for server_host_key");
key_free(server_host_key);
free(signature);
/* save session id */
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);
}
kex_derive_keys(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
void
kexdh_client(Kex *kex)
{
BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
DH *dh;
Key *server_host_key;
u_char *server_host_key_blob = NULL, *signature = NULL;
u_char *kbuf, *hash;
u_int klen, slen, sbloblen, hashlen;
int kout;
/* generate and send 'e', client 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);
packet_start(SSH2_MSG_KEXDH_INIT);
packet_put_bignum2(dh->pub_key);
packet_send();
debug("sending SSH2_MSG_KEXDH_INIT");
#ifdef DEBUG_KEXDH
DHparams_print_fp(stderr, dh);
fprintf(stderr, "pub= ");
BN_print_fp(stderr, dh->pub_key);
fprintf(stderr, "\n");
#endif
debug("expecting SSH2_MSG_KEXDH_REPLY");
packet_read_expect(SSH2_MSG_KEXDH_REPLY);
/* key, cert */
server_host_key_blob = packet_get_string(&sbloblen);
server_host_key = key_from_blob(server_host_key_blob, sbloblen);
if (server_host_key == NULL)
fatal("cannot decode server_host_key_blob");
if (server_host_key->type != kex->hostkey_type)
fatal("type mismatch for decoded server_host_key_blob");
if (kex->verify_host_key == NULL)
fatal("cannot verify server_host_key");
if (kex->verify_host_key(server_host_key) == -1)
fatal("server_host_key verification failed");
/* DH parameter f, server public DH key */
if ((dh_server_pub = BN_new()) == NULL)
fatal("dh_server_pub == NULL");
packet_get_bignum2(dh_server_pub);
#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
/* signed H */
signature = packet_get_string(&slen);
packet_check_eom();
if (!dh_pub_is_valid(dh, dh_server_pub))
packet_disconnect("bad server public DH value");
klen = DH_size(dh);
kbuf = xmalloc(klen);
if ((kout = DH_compute_key(kbuf, dh_server_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("kexdh_client: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexdh_client: BN_bin2bn failed");
memset(kbuf, 0, klen);
free(kbuf);
/* calc and verify H */
kex_dh_hash(
kex->client_version_string,
kex->server_version_string,
buffer_ptr(&kex->my), buffer_len(&kex->my),
buffer_ptr(&kex->peer), buffer_len(&kex->peer),
server_host_key_blob, sbloblen,
dh->pub_key,
dh_server_pub,
shared_secret,
&hash, &hashlen
);
free(server_host_key_blob);
BN_clear_free(dh_server_pub);
DH_free(dh);
if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
fatal("key_verify failed for server_host_key");
key_free(server_host_key);
free(signature);
/* save session id */
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);
}
kex_derive_keys(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
}
/*
* SSH1 key exchange
*/
void
do_ssh1_kex(void)
{
int i, len;
int rsafail = 0;
BIGNUM *session_key_int;
u_char session_key[SSH_SESSION_KEY_LENGTH];
u_char cookie[8];
u_int cipher_type, auth_mask, protocol_flags;
u_int32_t rnd = 0;
/*
* Generate check bytes that the client must send back in the user
* packet in order for it to be accepted; this is used to defy ip
* spoofing attacks. Note that this only works against somebody
* doing IP spoofing from a remote machine; any machine on the local
* network can still see outgoing packets and catch the random
* cookie. This only affects rhosts authentication, and this is one
* of the reasons why it is inherently insecure.
*/
for (i = 0; i < 8; i++) {
if (i % 4 == 0)
rnd = arc4random();
cookie[i] = rnd & 0xff;
rnd >>= 8;
}
/*
* Send our public key. We include in the packet 64 bits of random
* data that must be matched in the reply in order to prevent IP
* spoofing.
*/
packet_start(SSH_SMSG_PUBLIC_KEY);
for (i = 0; i < 8; i++)
packet_put_char(cookie[i]);
/* Store our public server RSA key. */
packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
packet_put_bignum(sensitive_data.server_key->rsa->e);
packet_put_bignum(sensitive_data.server_key->rsa->n);
/* Store our public host RSA key. */
packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
/* Put protocol flags. */
packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
/* Declare which ciphers we support. */
packet_put_int(cipher_mask_ssh1(0));
/* Declare supported authentication types. */
auth_mask = 0;
if (options.rhosts_rsa_authentication)
auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
if (options.rsa_authentication)
auth_mask |= 1 << SSH_AUTH_RSA;
if (options.challenge_response_authentication == 1)
auth_mask |= 1 << SSH_AUTH_TIS;
if (options.password_authentication)
auth_mask |= 1 << SSH_AUTH_PASSWORD;
packet_put_int(auth_mask);
/* Send the packet and wait for it to be sent. */
packet_send();
packet_write_wait();
debug("Sent %d bit server key and %d bit host key.",
BN_num_bits(sensitive_data.server_key->rsa->n),
BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
/* Read clients reply (cipher type and session key). */
packet_read_expect(SSH_CMSG_SESSION_KEY);
/* Get cipher type and check whether we accept this. */
cipher_type = packet_get_char();
if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
packet_disconnect("Warning: client selects unsupported cipher.");
/* Get check bytes from the packet. These must match those we
sent earlier with the public key packet. */
for (i = 0; i < 8; i++)
if (cookie[i] != packet_get_char())
packet_disconnect("IP Spoofing check bytes do not match.");
debug("Encryption type: %.200s", cipher_name(cipher_type));
/* Get the encrypted integer. */
if ((session_key_int = BN_new()) == NULL)
fatal("do_ssh1_kex: BN_new failed");
packet_get_bignum(session_key_int);
protocol_flags = packet_get_int();
packet_set_protocol_flags(protocol_flags);
packet_check_eom();
/* Decrypt session_key_int using host/server keys */
rsafail = PRIVSEP(ssh1_session_key(session_key_int));
/*
* Extract session key from the decrypted integer. The key is in the
* least significant 256 bits of the integer; the first byte of the
* key is in the highest bits.
*/
if (!rsafail) {
BN_mask_bits(session_key_int, sizeof(session_key) * 8);
len = BN_num_bytes(session_key_int);
if (len < 0 || len > sizeof(session_key)) {
error("do_connection: bad session key len from %s: "
"session_key_int %d > sizeof(session_key) %lu",
get_remote_ipaddr(), len, (u_long)sizeof(session_key));
rsafail++;
} else {
memset(session_key, 0, sizeof(session_key));
BN_bn2bin(session_key_int,
session_key + sizeof(session_key) - len);
derive_ssh1_session_id(
sensitive_data.ssh1_host_key->rsa->n,
sensitive_data.server_key->rsa->n,
cookie, session_id);
/*
* Xor the first 16 bytes of the session key with the
* session id.
*/
for (i = 0; i < 16; i++)
session_key[i] ^= session_id[i];
}
}
if (rsafail) {
int bytes = BN_num_bytes(session_key_int);
u_char *buf = xmalloc(bytes);
MD5_CTX md;
logit("do_connection: generating a fake encryption key");
BN_bn2bin(session_key_int, buf);
MD5_Init(&md);
MD5_Update(&md, buf, bytes);
MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
MD5_Final(session_key, &md);
MD5_Init(&md);
MD5_Update(&md, session_key, 16);
MD5_Update(&md, buf, bytes);
MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
MD5_Final(session_key + 16, &md);
memset(buf, 0, bytes);
xfree(buf);
for (i = 0; i < 16; i++)
session_id[i] = session_key[i] ^ session_key[i + 16];
}
/* Destroy the private and public keys. No longer. */
destroy_sensitive_data();
if (use_privsep)
mm_ssh1_session_id(session_id);
/* Destroy the decrypted integer. It is no longer needed. */
BN_clear_free(session_key_int);
/* Set the session key. From this on all communications will be encrypted. */
packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
/* Destroy our copy of the session key. It is no longer needed. */
memset(session_key, 0, sizeof(session_key));
debug("Received session key; encryption turned on.");
/* Send an acknowledgment packet. Note that this packet is sent encrypted. */
packet_start(SSH_SMSG_SUCCESS);
packet_send();
packet_write_wait();
}
static int
ssh_session2(void)
{
int id = -1;
/* XXX should be pre-session */
if (!options.control_persist)
ssh_init_stdio_forwarding();
ssh_init_forwarding();
/* Start listening for multiplex clients */
muxserver_listen();
/*
* If we are in control persist mode and have a working mux listen
* socket, then prepare to background ourselves and have a foreground
* client attach as a control slave.
* NB. we must save copies of the flags that we override for
* the backgrounding, since we defer attachment of the slave until
* after the connection is fully established (in particular,
* async rfwd replies have been received for ExitOnForwardFailure).
*/
if (options.control_persist && muxserver_sock != -1) {
ostdin_null_flag = stdin_null_flag;
ono_shell_flag = no_shell_flag;
orequest_tty = options.request_tty;
otty_flag = tty_flag;
stdin_null_flag = 1;
no_shell_flag = 1;
tty_flag = 0;
if (!fork_after_authentication_flag)
need_controlpersist_detach = 1;
fork_after_authentication_flag = 1;
}
/*
* ControlPersist mux listen socket setup failed, attempt the
* stdio forward setup that we skipped earlier.
*/
if (options.control_persist && muxserver_sock == -1)
ssh_init_stdio_forwarding();
if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
id = ssh_session2_open();
/* If we don't expect to open a new session, then disallow it */
if (options.control_master == SSHCTL_MASTER_NO &&
(datafellows & SSH_NEW_OPENSSH)) {
debug("Requesting [email protected]");
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("*****@*****.**");
packet_put_char(0);
packet_send();
}
/* Execute a local command */
if (options.local_command != NULL &&
options.permit_local_command)
ssh_local_cmd(options.local_command);
/*
* If requested and we are not interested in replies to remote
* forwarding requests, then let ssh continue in the background.
*/
if (fork_after_authentication_flag) {
if (options.exit_on_forward_failure &&
options.num_remote_forwards > 0) {
debug("deferring postauth fork until remote forward "
"confirmation received");
} else
fork_postauth();
}
if (options.use_roaming)
request_roaming();
return client_loop(tty_flag, tty_flag ?
options.escape_char : SSH_ESCAPECHAR_NONE, id);
}
void
kexgss_server(Kex *kex)
{
OM_uint32 maj_status, min_status;
/*
* Some GSSAPI implementations use the input value of ret_flags (an
* output variable) as a means of triggering mechanism specific
* features. Initializing it to zero avoids inadvertently
* activating this non-standard behaviour.
*/
OM_uint32 ret_flags = 0;
gss_buffer_desc gssbuf, recv_tok, msg_tok;
gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
Gssctxt *ctxt = NULL;
u_int slen, klen, kout, hashlen;
u_char *kbuf, *hash;
DH *dh;
int min = -1, max = -1, nbits = -1;
BIGNUM *shared_secret = NULL;
BIGNUM *dh_client_pub = NULL;
int type = 0;
gss_OID oid;
char *mechs;
/* Initialise GSSAPI */
/* If we're rekeying, privsep means that some of the private structures
* in the GSSAPI code are no longer available. This kludges them back
* into life
*/
if (!ssh_gssapi_oid_table_ok())
if ((mechs = ssh_gssapi_server_mechanisms()))
xfree(mechs);
debug2("%s: Identifying %s", __func__, kex->name);
oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type);
if (oid == GSS_C_NO_OID)
fatal("Unknown gssapi mechanism");
debug2("%s: Acquiring credentials", __func__);
if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid))))
fatal("Unable to acquire credentials for the server");
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
dh = dh_new_group1();
break;
case KEX_GSS_GRP14_SHA1:
dh = dh_new_group14();
break;
case KEX_GSS_GEX_SHA1:
debug("Doing group exchange");
packet_read_expect(SSH2_MSG_KEXGSS_GROUPREQ);
min = packet_get_int();
nbits = packet_get_int();
max = packet_get_int();
min = MAX(DH_GRP_MIN, min);
max = MIN(DH_GRP_MAX, max);
packet_check_eom();
if (max < min || nbits < min || max < nbits)
fatal("GSS_GEX, bad parameters: %d !< %d !< %d",
min, nbits, max);
dh = PRIVSEP(choose_dh(min, nbits, max));
if (dh == NULL)
packet_disconnect("Protocol error: no matching group found");
packet_start(SSH2_MSG_KEXGSS_GROUP);
packet_put_bignum2(dh->p);
packet_put_bignum2(dh->g);
packet_send();
packet_write_wait();
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
dh_gen_key(dh, kex->we_need * 8);
do {
debug("Wait SSH2_MSG_GSSAPI_INIT");
type = packet_read();
switch(type) {
case SSH2_MSG_KEXGSS_INIT:
if (dh_client_pub != NULL)
fatal("Received KEXGSS_INIT after initialising");
recv_tok.value = packet_get_string(&slen);
recv_tok.length = slen;
if ((dh_client_pub = BN_new()) == NULL)
fatal("dh_client_pub == NULL");
packet_get_bignum2(dh_client_pub);
/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
break;
case SSH2_MSG_KEXGSS_CONTINUE:
recv_tok.value = packet_get_string(&slen);
recv_tok.length = slen;
break;
default:
packet_disconnect(
"Protocol error: didn't expect packet type %d",
type);
}
maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok,
&send_tok, &ret_flags));
xfree(recv_tok.value);
if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
fatal("Zero length token output when incomplete");
if (dh_client_pub == NULL)
fatal("No client public key");
if (maj_status & GSS_S_CONTINUE_NEEDED) {
debug("Sending GSSAPI_CONTINUE");
packet_start(SSH2_MSG_KEXGSS_CONTINUE);
packet_put_string(send_tok.value, send_tok.length);
packet_send();
gss_release_buffer(&min_status, &send_tok);
}
} while (maj_status & GSS_S_CONTINUE_NEEDED);
if (GSS_ERROR(maj_status)) {
if (send_tok.length > 0) {
packet_start(SSH2_MSG_KEXGSS_CONTINUE);
packet_put_string(send_tok.value, send_tok.length);
packet_send();
}
fatal("accept_ctx died");
}
if (!(ret_flags & GSS_C_MUTUAL_FLAG))
fatal("Mutual Authentication flag wasn't set");
if (!(ret_flags & GSS_C_INTEG_FLAG))
fatal("Integrity flag wasn't set");
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);
if (kout < 0)
fatal("DH_compute_key: failed");
shared_secret = BN_new();
if (shared_secret == NULL)
fatal("kexgss_server: BN_new failed");
if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
fatal("kexgss_server: BN_bin2bn failed");
memset(kbuf, 0, klen);
xfree(kbuf);
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
case KEX_GSS_GRP14_SHA1:
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),
NULL, 0, /* Change this if we start sending host keys */
dh_client_pub, dh->pub_key, shared_secret,
&hash, &hashlen
);
break;
case KEX_GSS_GEX_SHA1:
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),
NULL, 0,
min, nbits, max,
dh->p, dh->g,
dh_client_pub,
dh->pub_key,
shared_secret,
&hash, &hashlen
);
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
BN_clear_free(dh_client_pub);
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);
}
gssbuf.value = hash;
gssbuf.length = hashlen;
if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt,&gssbuf,&msg_tok))))
fatal("Couldn't get MIC");
packet_start(SSH2_MSG_KEXGSS_COMPLETE);
packet_put_bignum2(dh->pub_key);
packet_put_string(msg_tok.value,msg_tok.length);
if (send_tok.length != 0) {
packet_put_char(1); /* true */
packet_put_string(send_tok.value, send_tok.length);
} else {
packet_put_char(0); /* false */
}
packet_send();
gss_release_buffer(&min_status, &send_tok);
gss_release_buffer(&min_status, &msg_tok);
if (gss_kex_context == NULL)
gss_kex_context = ctxt;
else
ssh_gssapi_delete_ctx(&ctxt);
DH_free(dh);
kex_derive_keys(kex, hash, hashlen, shared_secret);
BN_clear_free(shared_secret);
kex_finish(kex);
/* If this was a rekey, then save out any delegated credentials we
* just exchanged. */
if (options.gss_store_rekey)
ssh_gssapi_rekey_creds();
}
/*
* Performs the interactive session. This handles data transmission between
* the client and the program. Note that the notion of stdin, stdout, and
* stderr in this function is sort of reversed: this function writes to
* stdin (of the child program), and reads from stdout and stderr (of the
* child program).
*/
void
server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
{
fd_set *readset = NULL, *writeset = NULL;
int max_fd = 0;
u_int nalloc = 0;
int wait_status; /* Status returned by wait(). */
pid_t wait_pid; /* pid returned by wait(). */
int waiting_termination = 0; /* Have displayed waiting close message. */
u_int64_t max_time_milliseconds;
u_int previous_stdout_buffer_bytes;
u_int stdout_buffer_bytes;
int type;
debug("Entering interactive session.");
/* Initialize the SIGCHLD kludge. */
child_terminated = 0;
mysignal(SIGCHLD, sigchld_handler);
if (!use_privsep) {
signal(SIGTERM, sigterm_handler);
signal(SIGINT, sigterm_handler);
signal(SIGQUIT, sigterm_handler);
}
/* Initialize our global variables. */
fdin = fdin_arg;
fdout = fdout_arg;
fderr = fderr_arg;
/* nonblocking IO */
set_nonblock(fdin);
set_nonblock(fdout);
/* we don't have stderr for interactive terminal sessions, see below */
if (fderr != -1)
set_nonblock(fderr);
if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
fdin_is_tty = 1;
connection_in = packet_get_connection_in();
connection_out = packet_get_connection_out();
notify_setup();
previous_stdout_buffer_bytes = 0;
/* Set approximate I/O buffer size. */
if (packet_is_interactive())
buffer_high = 4096;
else
buffer_high = 64 * 1024;
#if 0
/* Initialize max_fd to the maximum of the known file descriptors. */
max_fd = MAX(connection_in, connection_out);
max_fd = MAX(max_fd, fdin);
max_fd = MAX(max_fd, fdout);
if (fderr != -1)
max_fd = MAX(max_fd, fderr);
#endif
/* Initialize Initialize buffers. */
buffer_init(&stdin_buffer);
buffer_init(&stdout_buffer);
buffer_init(&stderr_buffer);
/*
* If we have no separate fderr (which is the case when we have a pty
* - there we cannot make difference between data sent to stdout and
* stderr), indicate that we have seen an EOF from stderr. This way
* we don't need to check the descriptor everywhere.
*/
if (fderr == -1)
fderr_eof = 1;
server_init_dispatch();
/* Main loop of the server for the interactive session mode. */
for (;;) {
/* Process buffered packets from the client. */
process_buffered_input_packets();
/*
* If we have received eof, and there is no more pending
* input data, cause a real eof by closing fdin.
*/
if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
if (fdin != fdout)
close(fdin);
else
shutdown(fdin, SHUT_WR); /* We will no longer send. */
fdin = -1;
}
/* Make packets from buffered stderr data to send to the client. */
make_packets_from_stderr_data();
/*
* Make packets from buffered stdout data to send to the
* client. If there is very little to send, this arranges to
* not send them now, but to wait a short while to see if we
* are getting more data. This is necessary, as some systems
* wake up readers from a pty after each separate character.
*/
max_time_milliseconds = 0;
stdout_buffer_bytes = buffer_len(&stdout_buffer);
if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
stdout_buffer_bytes != previous_stdout_buffer_bytes) {
/* try again after a while */
max_time_milliseconds = 10;
} else {
/* Send it now. */
make_packets_from_stdout_data();
}
previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
/* Send channel data to the client. */
if (packet_not_very_much_data_to_write())
channel_output_poll();
/*
* Bail out of the loop if the program has closed its output
* descriptors, and we have no more data to send to the
* client, and there is no pending buffered data.
*/
if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
if (!channel_still_open())
break;
if (!waiting_termination) {
const char *s = "Waiting for forwarded connections to terminate... (press ~& to background)\r\n";
char *cp;
waiting_termination = 1;
buffer_append(&stderr_buffer, s, strlen(s));
/* Display list of open channels. */
cp = channel_open_message();
buffer_append(&stderr_buffer, cp, strlen(cp));
free(cp);
}
}
max_fd = MAX(connection_in, connection_out);
max_fd = MAX(max_fd, fdin);
max_fd = MAX(max_fd, fdout);
max_fd = MAX(max_fd, fderr);
max_fd = MAX(max_fd, notify_pipe[0]);
/* Sleep in select() until we can do something. */
wait_until_can_do_something(&readset, &writeset, &max_fd,
&nalloc, max_time_milliseconds);
if (received_sigterm) {
logit("Exiting on signal %d", (int)received_sigterm);
/* Clean up sessions, utmp, etc. */
cleanup_exit(255);
}
/* Process any channel events. */
channel_after_select(readset, writeset);
/* Process input from the client and from program stdout/stderr. */
process_input(readset);
/* Process output to the client and to program stdin. */
process_output(writeset);
}
free(readset);
free(writeset);
/* Cleanup and termination code. */
/* Wait until all output has been sent to the client. */
drain_output();
debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
/* Free and clear the buffers. */
buffer_free(&stdin_buffer);
buffer_free(&stdout_buffer);
buffer_free(&stderr_buffer);
/* Close the file descriptors. */
if (fdout != -1)
close(fdout);
fdout = -1;
fdout_eof = 1;
if (fderr != -1)
close(fderr);
fderr = -1;
fderr_eof = 1;
if (fdin != -1)
close(fdin);
fdin = -1;
channel_free_all();
/* We no longer want our SIGCHLD handler to be called. */
mysignal(SIGCHLD, SIG_DFL);
while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0)
if (errno != EINTR)
packet_disconnect("wait: %.100s", strerror(errno));
if (wait_pid != pid)
error("Strange, wait returned pid %ld, expected %ld",
(long)wait_pid, (long)pid);
/* Check if it exited normally. */
if (WIFEXITED(wait_status)) {
/* Yes, normal exit. Get exit status and send it to the client. */
debug("Command exited with status %d.", WEXITSTATUS(wait_status));
packet_start(SSH_SMSG_EXITSTATUS);
packet_put_int(WEXITSTATUS(wait_status));
packet_send();
packet_write_wait();
/*
* Wait for exit confirmation. Note that there might be
* other packets coming before it; however, the program has
* already died so we just ignore them. The client is
* supposed to respond with the confirmation when it receives
* the exit status.
*/
do {
type = packet_read();
}
while (type != SSH_CMSG_EXIT_CONFIRMATION);
debug("Received exit confirmation.");
return;
}
/* Check if the program terminated due to a signal. */
if (WIFSIGNALED(wait_status))
packet_disconnect("Command terminated on signal %d.",
WTERMSIG(wait_status));
/* Some weird exit cause. Just exit. */
packet_disconnect("wait returned status %04x.", wait_status);
/* NOTREACHED */
}
static int
roaming_resume(void)
{
u_int64_t recv_bytes;
char *str = NULL, *kexlist = NULL, *c;
int i, type;
int timeout_ms = options.connection_timeout * 1000;
u_int len;
u_int32_t rnd = 0;
resume_in_progress = 1;
/* Exchange banners */
ssh_exchange_identification(timeout_ms);
packet_set_nonblocking();
/* Send a kexinit message with [email protected] as only kex algo */
packet_start(SSH2_MSG_KEXINIT);
for (i = 0; i < KEX_COOKIE_LEN; i++) {
if (i % 4 == 0)
rnd = arc4random();
packet_put_char(rnd & 0xff);
rnd >>= 8;
}
packet_put_cstring(KEX_RESUME);
for (i = 1; i < PROPOSAL_MAX; i++) {
/* kex algorithm added so start with i=1 and not 0 */
packet_put_cstring(""); /* Not used when we resume */
}
packet_put_char(1); /* first kex_packet follows */
packet_put_int(0); /* reserved */
packet_send();
/* Assume that [email protected] will be accepted */
packet_start(SSH2_MSG_KEX_ROAMING_RESUME);
packet_put_int(roaming_id);
packet_send();
/* Read the server's kexinit and check for [email protected] */
if ((type = packet_read()) != SSH2_MSG_KEXINIT) {
debug("expected kexinit on resume, got %d", type);
goto fail;
}
for (i = 0; i < KEX_COOKIE_LEN; i++)
(void)packet_get_char();
kexlist = packet_get_string(&len);
if (!kexlist
|| (str = match_list(KEX_RESUME, kexlist, NULL)) == NULL) {
debug("server doesn't allow resume");
goto fail;
}
free(str);
for (i = 1; i < PROPOSAL_MAX; i++) {
/* kex algorithm taken care of so start with i=1 and not 0 */
free(packet_get_string(&len));
}
i = packet_get_char(); /* first_kex_packet_follows */
if (i && (c = strchr(kexlist, ',')))
*c = 0;
if (i && strcmp(kexlist, KEX_RESUME)) {
debug("server's kex guess (%s) was wrong, skipping", kexlist);
(void)packet_read(); /* Wrong guess - discard packet */
}
/*
* Read the ROAMING_AUTH_REQUIRED challenge from the server and
* send ROAMING_AUTH
*/
if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_REQUIRED) {
debug("expected roaming_auth_required, got %d", type);
goto fail;
}
roaming_auth_required();
/* Read ROAMING_AUTH_OK from the server */
if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_OK) {
debug("expected roaming_auth_ok, got %d", type);
goto fail;
}
recv_bytes = packet_get_int64() ^ oldkey2;
debug("Peer received %llu bytes", (unsigned long long)recv_bytes);
resend_bytes(packet_get_connection_out(), &recv_bytes);
resume_in_progress = 0;
session_resumed = 1; /* Tell clientloop */
return 0;
fail:
free(kexlist);
if (packet_get_connection_in() == packet_get_connection_out())
close(packet_get_connection_in());
else {
close(packet_get_connection_in());
close(packet_get_connection_out());
}
return 1;
}
