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authorDamien Miller <djm@mindrot.org>2000-04-29 23:57:08 +1000
committerDamien Miller <djm@mindrot.org>2000-04-29 23:57:08 +1000
commiteba71bab9bf01c0d688f829a8971f902732558df (patch)
treea9d5b50568bfc10cc50291fd3604debfaf3e3783 /sshconnect1.c
parent8117111a3c1360727e3c54aad31aa045e7a7871b (diff)
- Merge big update to OpenSSH-2.0 from OpenBSD CVS
[README.openssh2] - interop w/ F-secure windows client - sync documentation - ssh_host_dsa_key not ssh_dsa_key [auth-rsa.c] - missing fclose [auth.c authfile.c compat.c dsa.c dsa.h hostfile.c key.c key.h radix.c] [readconf.c readconf.h ssh-add.c ssh-keygen.c ssh.c ssh.h sshconnect.c] [sshd.c uuencode.c uuencode.h authfile.h] - add DSA pubkey auth and other SSH2 fixes. use ssh-keygen -[xX] for trading keys with the real and the original SSH, directly from the people who invented the SSH protocol. [auth.c auth.h authfile.c sshconnect.c auth1.c auth2.c sshconnect.h] [sshconnect1.c sshconnect2.c] - split auth/sshconnect in one file per protocol version [sshconnect2.c] - remove debug [uuencode.c] - add trailing = [version.h] - OpenSSH-2.0 [ssh-keygen.1 ssh-keygen.c] - add -R flag: exit code indicates if RSA is alive [sshd.c] - remove unused silent if -Q is specified [ssh.h] - host key becomes /etc/ssh_host_dsa_key [readconf.c servconf.c ] - ssh/sshd default to proto 1 and 2 [uuencode.c] - remove debug [auth2.c ssh-keygen.c sshconnect2.c sshd.c] - xfree DSA blobs [auth2.c serverloop.c session.c] - cleanup logging for sshd/2, respect PasswordAuth no [sshconnect2.c] - less debug, respect .ssh/config [README.openssh2 channels.c channels.h] - clientloop.c session.c ssh.c - support for x11-fwding, client+server
Diffstat (limited to 'sshconnect1.c')
-rw-r--r--sshconnect1.c1020
1 files changed, 1020 insertions, 0 deletions
diff --git a/sshconnect1.c b/sshconnect1.c
new file mode 100644
index 00000000..c5a76654
--- /dev/null
+++ b/sshconnect1.c
@@ -0,0 +1,1020 @@
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ * All rights reserved
+ * Created: Sat Mar 18 22:15:47 1995 ylo
+ * Code to connect to a remote host, and to perform the client side of the
+ * login (authentication) dialog.
+ *
+ */
+
+#include "includes.h"
+RCSID("$OpenBSD: sshconnect1.c,v 1.1 2000/04/26 21:28:33 markus Exp $");
+
+#include <openssl/bn.h>
+#include <openssl/dsa.h>
+#include <openssl/rsa.h>
+#include <openssl/evp.h>
+
+#include "xmalloc.h"
+#include "rsa.h"
+#include "ssh.h"
+#include "buffer.h"
+#include "packet.h"
+#include "authfd.h"
+#include "cipher.h"
+#include "mpaux.h"
+#include "uidswap.h"
+#include "readconf.h"
+#include "key.h"
+#include "sshconnect.h"
+#include "authfile.h"
+
+/* Session id for the current session. */
+unsigned char session_id[16];
+unsigned int supported_authentications = 0;
+
+extern Options options;
+extern char *__progname;
+
+/*
+ * Checks if the user has an authentication agent, and if so, tries to
+ * authenticate using the agent.
+ */
+int
+try_agent_authentication()
+{
+ int status, type;
+ char *comment;
+ AuthenticationConnection *auth;
+ unsigned char response[16];
+ unsigned int i;
+ BIGNUM *e, *n, *challenge;
+
+ /* Get connection to the agent. */
+ auth = ssh_get_authentication_connection();
+ if (!auth)
+ return 0;
+
+ e = BN_new();
+ n = BN_new();
+ challenge = BN_new();
+
+ /* Loop through identities served by the agent. */
+ for (status = ssh_get_first_identity(auth, e, n, &comment);
+ status;
+ status = ssh_get_next_identity(auth, e, n, &comment)) {
+ int plen, clen;
+
+ /* 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(n);
+ packet_send();
+ packet_write_wait();
+
+ /* Wait for server's response. */
+ type = packet_read(&plen);
+
+ /* 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.");
+ 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, &clen);
+
+ packet_integrity_check(plen, clen, type);
+
+ debug("Received RSA challenge from server.");
+
+ /* Ask the agent to decrypt the challenge. */
+ if (!ssh_decrypt_challenge(auth, e, n, 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));
+ }
+ 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(&plen);
+
+ /* The server returns success if it accepted the authentication. */
+ if (type == SSH_SMSG_SUCCESS) {
+ debug("RSA authentication accepted by server.");
+ BN_clear_free(e);
+ BN_clear_free(n);
+ BN_clear_free(challenge);
+ return 1;
+ }
+ /* Otherwise it should return failure. */
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error waiting RSA auth response: %d",
+ type);
+ }
+
+ BN_clear_free(e);
+ BN_clear_free(n);
+ BN_clear_free(challenge);
+
+ debug("RSA authentication using agent refused.");
+ return 0;
+}
+
+/*
+ * Computes the proper response to a RSA challenge, and sends the response to
+ * the server.
+ */
+void
+respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv)
+{
+ unsigned char buf[32], response[16];
+ MD5_CTX md;
+ int i, len;
+
+ /* Decrypt the challenge using the private key. */
+ rsa_private_decrypt(challenge, challenge, prv);
+
+ /* Compute the response. */
+ /* The response is MD5 of decrypted challenge plus session id. */
+ len = BN_num_bytes(challenge);
+ if (len <= 0 || len > sizeof(buf))
+ packet_disconnect("respond_to_rsa_challenge: bad challenge length %d",
+ len);
+
+ memset(buf, 0, sizeof(buf));
+ BN_bn2bin(challenge, buf + sizeof(buf) - len);
+ MD5_Init(&md);
+ MD5_Update(&md, buf, 32);
+ MD5_Update(&md, session_id, 16);
+ MD5_Final(response, &md);
+
+ debug("Sending response to host key RSA challenge.");
+
+ /* Send the response 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();
+
+ memset(buf, 0, sizeof(buf));
+ memset(response, 0, sizeof(response));
+ memset(&md, 0, sizeof(md));
+}
+
+/*
+ * Checks if the user has authentication file, and if so, tries to authenticate
+ * the user using it.
+ */
+int
+try_rsa_authentication(const char *authfile)
+{
+ BIGNUM *challenge;
+ Key *public;
+ Key *private;
+ char *passphrase, *comment;
+ int type, i;
+ int plen, clen;
+
+ /* Try to load identification for the authentication key. */
+ public = key_new(KEY_RSA);
+ if (!load_public_key(authfile, public, &comment)) {
+ key_free(public);
+ /* Could not load it. Fail. */
+ return 0;
+ }
+ debug("Trying RSA authentication with key '%.100s'", comment);
+
+ /* Tell the server that we are willing to authenticate using this key. */
+ packet_start(SSH_CMSG_AUTH_RSA);
+ packet_put_bignum(public->rsa->n);
+ packet_send();
+ packet_write_wait();
+
+ /* We no longer need the public key. */
+ key_free(public);
+
+ /* Wait for server's response. */
+ type = packet_read(&plen);
+
+ /*
+ * The server responds with failure if it doesn\'t like our key or
+ * doesn\'t support RSA authentication.
+ */
+ if (type == SSH_SMSG_FAILURE) {
+ debug("Server refused our key.");
+ xfree(comment);
+ return 0;
+ }
+ /* Otherwise, the server should respond with a challenge. */
+ if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
+ packet_disconnect("Protocol error during RSA authentication: %d", type);
+
+ /* Get the challenge from the packet. */
+ challenge = BN_new();
+ packet_get_bignum(challenge, &clen);
+
+ packet_integrity_check(plen, clen, type);
+
+ debug("Received RSA challenge from server.");
+
+ private = key_new(KEY_RSA);
+ /*
+ * Load the private key. Try first with empty passphrase; if it
+ * fails, ask for a passphrase.
+ */
+ if (!load_private_key(authfile, "", private, NULL)) {
+ char buf[300];
+ snprintf(buf, sizeof buf, "Enter passphrase for RSA key '%.100s': ",
+ comment);
+ if (!options.batch_mode)
+ passphrase = read_passphrase(buf, 0);
+ else {
+ debug("Will not query passphrase for %.100s in batch mode.",
+ comment);
+ passphrase = xstrdup("");
+ }
+
+ /* Load the authentication file using the pasphrase. */
+ if (!load_private_key(authfile, passphrase, private, NULL)) {
+ memset(passphrase, 0, strlen(passphrase));
+ xfree(passphrase);
+ error("Bad passphrase.");
+
+ /* Send a dummy response packet to avoid protocol error. */
+ packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
+ for (i = 0; i < 16; i++)
+ packet_put_char(0);
+ packet_send();
+ packet_write_wait();
+
+ /* Expect the server to reject it... */
+ packet_read_expect(&plen, SSH_SMSG_FAILURE);
+ xfree(comment);
+ return 0;
+ }
+ /* Destroy the passphrase. */
+ memset(passphrase, 0, strlen(passphrase));
+ xfree(passphrase);
+ }
+ /* We no longer need the comment. */
+ xfree(comment);
+
+ /* Compute and send a response to the challenge. */
+ respond_to_rsa_challenge(challenge, private->rsa);
+
+ /* Destroy the private key. */
+ key_free(private);
+
+ /* We no longer need the challenge. */
+ BN_clear_free(challenge);
+
+ /* Wait for response from the server. */
+ type = packet_read(&plen);
+ if (type == SSH_SMSG_SUCCESS) {
+ debug("RSA authentication accepted by server.");
+ return 1;
+ }
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error waiting RSA auth response: %d", type);
+ debug("RSA authentication refused.");
+ return 0;
+}
+
+/*
+ * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
+ * authentication and RSA host authentication.
+ */
+int
+try_rhosts_rsa_authentication(const char *local_user, RSA * host_key)
+{
+ int type;
+ BIGNUM *challenge;
+ int plen, clen;
+
+ debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
+
+ /* Tell the server that we are willing to authenticate using this key. */
+ packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
+ packet_put_string(local_user, strlen(local_user));
+ packet_put_int(BN_num_bits(host_key->n));
+ packet_put_bignum(host_key->e);
+ packet_put_bignum(host_key->n);
+ packet_send();
+ packet_write_wait();
+
+ /* Wait for server's response. */
+ type = packet_read(&plen);
+
+ /* The server responds with failure if it doesn't admit our
+ .rhosts authentication or doesn't know our host key. */
+ if (type == SSH_SMSG_FAILURE) {
+ debug("Server refused our rhosts authentication or host key.");
+ return 0;
+ }
+ /* Otherwise, the server should respond with a challenge. */
+ if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
+ packet_disconnect("Protocol error during RSA authentication: %d", type);
+
+ /* Get the challenge from the packet. */
+ challenge = BN_new();
+ packet_get_bignum(challenge, &clen);
+
+ packet_integrity_check(plen, clen, type);
+
+ debug("Received RSA challenge for host key from server.");
+
+ /* Compute a response to the challenge. */
+ respond_to_rsa_challenge(challenge, host_key);
+
+ /* We no longer need the challenge. */
+ BN_clear_free(challenge);
+
+ /* Wait for response from the server. */
+ type = packet_read(&plen);
+ if (type == SSH_SMSG_SUCCESS) {
+ debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
+ return 1;
+ }
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error waiting RSA auth response: %d", type);
+ debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
+ return 0;
+}
+
+#ifdef KRB4
+int
+try_kerberos_authentication()
+{
+ KTEXT_ST auth; /* Kerberos data */
+ char *reply;
+ char inst[INST_SZ];
+ char *realm;
+ CREDENTIALS cred;
+ int r, type, plen;
+ socklen_t slen;
+ Key_schedule schedule;
+ u_long checksum, cksum;
+ MSG_DAT msg_data;
+ struct sockaddr_in local, foreign;
+ struct stat st;
+
+ /* Don't do anything if we don't have any tickets. */
+ if (stat(tkt_string(), &st) < 0)
+ return 0;
+
+ strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ);
+
+ realm = (char *) krb_realmofhost(get_canonical_hostname());
+ if (!realm) {
+ debug("Kerberos V4: no realm for %s", get_canonical_hostname());
+ return 0;
+ }
+ /* This can really be anything. */
+ checksum = (u_long) getpid();
+
+ r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
+ if (r != KSUCCESS) {
+ debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]);
+ return 0;
+ }
+ /* Get session key to decrypt the server's reply with. */
+ r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
+ if (r != KSUCCESS) {
+ debug("get_cred failed: %s", krb_err_txt[r]);
+ return 0;
+ }
+ des_key_sched((des_cblock *) cred.session, schedule);
+
+ /* Send authentication info to server. */
+ packet_start(SSH_CMSG_AUTH_KERBEROS);
+ packet_put_string((char *) auth.dat, auth.length);
+ packet_send();
+ packet_write_wait();
+
+ /* Zero the buffer. */
+ (void) memset(auth.dat, 0, MAX_KTXT_LEN);
+
+ slen = sizeof(local);
+ memset(&local, 0, sizeof(local));
+ if (getsockname(packet_get_connection_in(),
+ (struct sockaddr *) & local, &slen) < 0)
+ debug("getsockname failed: %s", strerror(errno));
+
+ slen = sizeof(foreign);
+ memset(&foreign, 0, sizeof(foreign));
+ if (getpeername(packet_get_connection_in(),
+ (struct sockaddr *) & foreign, &slen) < 0) {
+ debug("getpeername failed: %s", strerror(errno));
+ fatal_cleanup();
+ }
+ /* Get server reply. */
+ type = packet_read(&plen);
+ switch (type) {
+ case SSH_SMSG_FAILURE:
+ /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
+ debug("Kerberos V4 authentication failed.");
+ return 0;
+ break;
+
+ case SSH_SMSG_AUTH_KERBEROS_RESPONSE:
+ /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
+ debug("Kerberos V4 authentication accepted.");
+
+ /* Get server's response. */
+ reply = packet_get_string((unsigned int *) &auth.length);
+ memcpy(auth.dat, reply, auth.length);
+ xfree(reply);
+
+ packet_integrity_check(plen, 4 + auth.length, type);
+
+ /*
+ * If his response isn't properly encrypted with the session
+ * key, and the decrypted checksum fails to match, he's
+ * bogus. Bail out.
+ */
+ r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session,
+ &foreign, &local, &msg_data);
+ if (r != KSUCCESS) {
+ debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]);
+ packet_disconnect("Kerberos V4 challenge failed!");
+ }
+ /* Fetch the (incremented) checksum that we supplied in the request. */
+ (void) memcpy((char *) &cksum, (char *) msg_data.app_data, sizeof(cksum));
+ cksum = ntohl(cksum);
+
+ /* If it matches, we're golden. */
+ if (cksum == checksum + 1) {
+ debug("Kerberos V4 challenge successful.");
+ return 1;
+ } else
+ packet_disconnect("Kerberos V4 challenge failed!");
+ break;
+
+ default:
+ packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
+ }
+ return 0;
+}
+
+#endif /* KRB4 */
+
+#ifdef AFS
+int
+send_kerberos_tgt()
+{
+ CREDENTIALS *creds;
+ char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
+ int r, type, plen;
+ char buffer[8192];
+ struct stat st;
+
+ /* Don't do anything if we don't have any tickets. */
+ if (stat(tkt_string(), &st) < 0)
+ return 0;
+
+ creds = xmalloc(sizeof(*creds));
+
+ if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) {
+ debug("Kerberos V4 tf_fullname failed: %s", krb_err_txt[r]);
+ return 0;
+ }
+ if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) {
+ debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]);
+ return 0;
+ }
+ if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
+ debug("Kerberos V4 ticket expired: %s", TKT_FILE);
+ return 0;
+ }
+ creds_to_radix(creds, (unsigned char *)buffer);
+ xfree(creds);
+
+ packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
+ packet_put_string(buffer, strlen(buffer));
+ packet_send();
+ packet_write_wait();
+
+ type = packet_read(&plen);
+
+ if (type == SSH_SMSG_FAILURE)
+ debug("Kerberos TGT for realm %s rejected.", prealm);
+ else if (type != SSH_SMSG_SUCCESS)
+ packet_disconnect("Protocol error on Kerberos TGT response: %d", type);
+
+ return 1;
+}
+
+void
+send_afs_tokens(void)
+{
+ CREDENTIALS creds;
+ struct ViceIoctl parms;
+ struct ClearToken ct;
+ int i, type, len, plen;
+ char buf[2048], *p, *server_cell;
+ char buffer[8192];
+
+ /* Move over ktc_GetToken, here's something leaner. */
+ for (i = 0; i < 100; i++) { /* just in case */
+ parms.in = (char *) &i;
+ parms.in_size = sizeof(i);
+ parms.out = buf;
+ parms.out_size = sizeof(buf);
+ if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0)
+ break;
+ p = buf;
+
+ /* Get secret token. */
+ memcpy(&creds.ticket_st.length, p, sizeof(unsigned int));
+ if (creds.ticket_st.length > MAX_KTXT_LEN)
+ break;
+ p += sizeof(unsigned int);
+ memcpy(creds.ticket_st.dat, p, creds.ticket_st.length);
+ p += creds.ticket_st.length;
+
+ /* Get clear token. */
+ memcpy(&len, p, sizeof(len));
+ if (len != sizeof(struct ClearToken))
+ break;
+ p += sizeof(len);
+ memcpy(&ct, p, len);
+ p += len;
+ p += sizeof(len); /* primary flag */
+ server_cell = p;
+
+ /* Flesh out our credentials. */
+ strlcpy(creds.service, "afs", sizeof creds.service);
+ creds.instance[0] = '\0';
+ strlcpy(creds.realm, server_cell, REALM_SZ);
+ memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ);
+ creds.issue_date = ct.BeginTimestamp;
+ creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp);
+ creds.kvno = ct.AuthHandle;
+ snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId);
+ creds.pinst[0] = '\0';
+
+ /* Encode token, ship it off. */
+ if (!creds_to_radix(&creds, (unsigned char*) buffer))
+ break;
+ packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
+ packet_put_string(buffer, strlen(buffer));
+ packet_send();
+ packet_write_wait();
+
+ /* Roger, Roger. Clearance, Clarence. What's your vector,
+ Victor? */
+ type = packet_read(&plen);
+
+ if (type == SSH_SMSG_FAILURE)
+ debug("AFS token for cell %s rejected.", server_cell);
+ else if (type != SSH_SMSG_SUCCESS)
+ packet_disconnect("Protocol error on AFS token response: %d", type);
+ }
+}
+
+#endif /* AFS */
+
+/*
+ * Tries to authenticate with any string-based challenge/response system.
+ * Note that the client code is not tied to s/key or TIS.
+ */
+int
+try_skey_authentication()
+{
+ int type, i;
+ int payload_len;
+ unsigned int clen;
+ char *challenge, *response;
+
+ debug("Doing skey authentication.");
+
+ /* request a challenge */
+ packet_start(SSH_CMSG_AUTH_TIS);
+ packet_send();
+ packet_write_wait();
+
+ type = packet_read(&payload_len);
+ if (type != SSH_SMSG_FAILURE &&
+ type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
+ packet_disconnect("Protocol error: got %d in response "
+ "to skey-auth", type);
+ }
+ if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
+ debug("No challenge for skey authentication.");
+ return 0;
+ }
+ challenge = packet_get_string(&clen);
+ packet_integrity_check(payload_len, (4 + clen), type);
+ if (options.cipher == SSH_CIPHER_NONE)
+ log("WARNING: Encryption is disabled! "
+ "Reponse will be transmitted in clear text.");
+ fprintf(stderr, "%s\n", challenge);
+ xfree(challenge);
+ fflush(stderr);
+ for (i = 0; i < options.number_of_password_prompts; i++) {
+ if (i != 0)
+ error("Permission denied, please try again.");
+ response = read_passphrase("Response: ", 0);
+ packet_start(SSH_CMSG_AUTH_TIS_RESPONSE);
+ packet_put_string(response, strlen(response));
+ memset(response, 0, strlen(response));
+ xfree(response);
+ packet_send();
+ packet_write_wait();
+ type = packet_read(&payload_len);
+ if (type == SSH_SMSG_SUCCESS)
+ return 1;
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error: got %d in response "
+ "to skey-auth-reponse", type);
+ }
+ /* failure */
+ return 0;
+}
+
+/*
+ * Tries to authenticate with plain passwd authentication.
+ */
+int
+try_password_authentication(char *prompt)
+{
+ int type, i, payload_len;
+ char *password;
+
+ debug("Doing password authentication.");
+ if (options.cipher == SSH_CIPHER_NONE)
+ log("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
+ for (i = 0; i < options.number_of_password_prompts; i++) {
+ if (i != 0)
+ error("Permission denied, please try again.");
+ password = read_passphrase(prompt, 0);
+ packet_start(SSH_CMSG_AUTH_PASSWORD);
+ packet_put_string(password, strlen(password));
+ memset(password, 0, strlen(password));
+ xfree(password);
+ packet_send();
+ packet_write_wait();
+
+ type = packet_read(&payload_len);
+ if (type == SSH_SMSG_SUCCESS)
+ return 1;
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error: got %d in response to passwd auth", type);
+ }
+ /* failure */
+ return 0;
+}
+
+/*
+ * SSH1 key exchange
+ */
+void
+ssh_kex(char *host, struct sockaddr *hostaddr)
+{
+ int i;
+ BIGNUM *key;
+ RSA *host_key;
+ RSA *public_key;
+ Key k;
+ int bits, rbits;
+ int ssh_cipher_default = SSH_CIPHER_3DES;
+ unsigned char session_key[SSH_SESSION_KEY_LENGTH];
+ unsigned char cookie[8];
+ unsigned int supported_ciphers;
+ unsigned int server_flags, client_flags;
+ int payload_len, clen, sum_len = 0;
+ u_int32_t rand = 0;
+
+ debug("Waiting for server public key.");
+
+ /* Wait for a public key packet from the server. */
+ packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY);
+
+ /* Get cookie from the packet. */
+ for (i = 0; i < 8; i++)
+ cookie[i] = packet_get_char();
+
+ /* Get the public key. */
+ public_key = RSA_new();
+ bits = packet_get_int();/* bits */
+ public_key->e = BN_new();
+ packet_get_bignum(public_key->e, &clen);
+ sum_len += clen;
+ public_key->n = BN_new();
+ packet_get_bignum(public_key->n, &clen);
+ sum_len += clen;
+
+ rbits = BN_num_bits(public_key->n);
+ if (bits != rbits) {
+ log("Warning: Server lies about size of server public key: "
+ "actual size is %d bits vs. announced %d.", rbits, bits);
+ log("Warning: This may be due to an old implementation of ssh.");
+ }
+ /* Get the host key. */
+ host_key = RSA_new();
+ bits = packet_get_int();/* bits */
+ host_key->e = BN_new();
+ packet_get_bignum(host_key->e, &clen);
+ sum_len += clen;
+ host_key->n = BN_new();
+ packet_get_bignum(host_key->n, &clen);
+ sum_len += clen;
+
+ rbits = BN_num_bits(host_key->n);
+ if (bits != rbits) {
+ log("Warning: Server lies about size of server host key: "
+ "actual size is %d bits vs. announced %d.", rbits, bits);
+ log("Warning: This may be due to an old implementation of ssh.");
+ }
+
+ /* Get protocol flags. */
+ server_flags = packet_get_int();
+ packet_set_protocol_flags(server_flags);
+
+ supported_ciphers = packet_get_int();
+ supported_authentications = packet_get_int();
+
+ debug("Received server public key (%d bits) and host key (%d bits).",
+ BN_num_bits(public_key->n), BN_num_bits(host_key->n));
+
+ packet_integrity_check(payload_len,
+ 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4,
+ SSH_SMSG_PUBLIC_KEY);
+ k.type = KEY_RSA;
+ k.rsa = host_key;
+ check_host_key(host, hostaddr, &k,
+ options.user_hostfile, options.system_hostfile);
+
+ client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN;
+
+ compute_session_id(session_id, cookie, host_key->n, public_key->n);
+
+ /* Generate a session key. */
+ arc4random_stir();
+
+ /*
+ * Generate an encryption key for the session. The key is a 256 bit
+ * random number, interpreted as a 32-byte key, with the least
+ * significant 8 bits being the first byte of the key.
+ */
+ for (i = 0; i < 32; i++) {
+ if (i % 4 == 0)
+ rand = arc4random();
+ session_key[i] = rand & 0xff;
+ rand >>= 8;
+ }
+
+ /*
+ * According to the protocol spec, the first byte of the session key
+ * is the highest byte of the integer. The session key is xored with
+ * the first 16 bytes of the session id.
+ */
+ key = BN_new();
+ BN_set_word(key, 0);
+ for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
+ BN_lshift(key, key, 8);
+ if (i < 16)
+ BN_add_word(key, session_key[i] ^ session_id[i]);
+ else
+ BN_add_word(key, session_key[i]);
+ }
+
+ /*
+ * Encrypt the integer using the public key and host key of the
+ * server (key with smaller modulus first).
+ */
+ if (BN_cmp(public_key->n, host_key->n) < 0) {
+ /* Public key has smaller modulus. */
+ if (BN_num_bits(host_key->n) <
+ BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) {
+ fatal("respond_to_rsa_challenge: host_key %d < public_key %d + "
+ "SSH_KEY_BITS_RESERVED %d",
+ BN_num_bits(host_key->n),
+ BN_num_bits(public_key->n),
+ SSH_KEY_BITS_RESERVED);
+ }
+ rsa_public_encrypt(key, key, public_key);
+ rsa_public_encrypt(key, key, host_key);
+ } else {
+ /* Host key has smaller modulus (or they are equal). */
+ if (BN_num_bits(public_key->n) <
+ BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) {
+ fatal("respond_to_rsa_challenge: public_key %d < host_key %d + "
+ "SSH_KEY_BITS_RESERVED %d",
+ BN_num_bits(public_key->n),
+ BN_num_bits(host_key->n),
+ SSH_KEY_BITS_RESERVED);
+ }
+ rsa_public_encrypt(key, key, host_key);
+ rsa_public_encrypt(key, key, public_key);
+ }
+
+ /* Destroy the public keys since we no longer need them. */
+ RSA_free(public_key);
+ RSA_free(host_key);
+
+ if (options.cipher == SSH_CIPHER_NOT_SET) {
+ if (cipher_mask1() & supported_ciphers & (1 << ssh_cipher_default))
+ options.cipher = ssh_cipher_default;
+ else {
+ debug("Cipher %s not supported, using %.100s instead.",
+ cipher_name(ssh_cipher_default),
+ cipher_name(SSH_FALLBACK_CIPHER));
+ options.cipher = SSH_FALLBACK_CIPHER;
+ }
+ }
+ /* Check that the selected cipher is supported. */
+ if (!(supported_ciphers & (1 << options.cipher)))
+ fatal("Selected cipher type %.100s not supported by server.",
+ cipher_name(options.cipher));
+
+ debug("Encryption type: %.100s", cipher_name(options.cipher));
+
+ /* Send the encrypted session key to the server. */
+ packet_start(SSH_CMSG_SESSION_KEY);
+ packet_put_char(options.cipher);
+
+ /* Send the cookie back to the server. */
+ for (i = 0; i < 8; i++)
+ packet_put_char(cookie[i]);
+
+ /* Send and destroy the encrypted encryption key integer. */
+ packet_put_bignum(key);
+ BN_clear_free(key);
+
+ /* Send protocol flags. */
+ packet_put_int(client_flags);
+
+ /* Send the packet now. */
+ packet_send();
+ packet_write_wait();
+
+ debug("Sent encrypted session key.");
+
+ /* Set the encryption key. */
+ packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher);
+
+ /* We will no longer need the session key here. Destroy any extra copies. */
+ memset(session_key, 0, sizeof(session_key));
+
+ /*
+ * Expect a success message from the server. Note that this message
+ * will be received in encrypted form.
+ */
+ packet_read_expect(&payload_len, SSH_SMSG_SUCCESS);
+
+ debug("Received encrypted confirmation.");
+}
+
+/*
+ * Authenticate user
+ */
+void
+ssh_userauth(
+ const char* local_user,
+ const char* server_user,
+ char *host,
+ int host_key_valid, RSA *own_host_key)
+{
+ int i, type;
+ int payload_len;
+
+ if (supported_authentications == 0)
+ fatal("ssh_userauth: server supports no auth methods");
+
+ /* Send the name of the user to log in as on the server. */
+ packet_start(SSH_CMSG_USER);
+ packet_put_string(server_user, strlen(server_user));
+ packet_send();
+ packet_write_wait();
+
+ /*
+ * The server should respond with success if no authentication is
+ * needed (the user has no password). Otherwise the server responds
+ * with failure.
+ */
+ type = packet_read(&payload_len);
+
+ /* check whether the connection was accepted without authentication. */
+ if (type == SSH_SMSG_SUCCESS)
+ return;
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER",
+ type);
+
+#ifdef AFS
+ /* Try Kerberos tgt passing if the server supports it. */
+ if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
+ options.kerberos_tgt_passing) {
+ if (options.cipher == SSH_CIPHER_NONE)
+ log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
+ (void) send_kerberos_tgt();
+ }
+ /* Try AFS token passing if the server supports it. */
+ if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) &&
+ options.afs_token_passing && k_hasafs()) {
+ if (options.cipher == SSH_CIPHER_NONE)
+ log("WARNING: Encryption is disabled! Token will be transmitted in the clear!");
+ send_afs_tokens();
+ }
+#endif /* AFS */
+
+#ifdef KRB4
+ if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
+ options.kerberos_authentication) {
+ debug("Trying Kerberos authentication.");
+ if (try_kerberos_authentication()) {
+ /* The server should respond with success or failure. */
+ type = packet_read(&payload_len);
+ if (type == SSH_SMSG_SUCCESS)
+ return;
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
+ }
+ }
+#endif /* KRB4 */
+
+ /*
+ * Use rhosts authentication if running in privileged socket and we
+ * do not wish to remain anonymous.
+ */
+ if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) &&
+ options.rhosts_authentication) {
+ debug("Trying rhosts authentication.");
+ packet_start(SSH_CMSG_AUTH_RHOSTS);
+ packet_put_string(local_user, strlen(local_user));
+ packet_send();
+ packet_write_wait();
+
+ /* The server should respond with success or failure. */
+ type = packet_read(&payload_len);
+ if (type == SSH_SMSG_SUCCESS)
+ return;
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error: got %d in response to rhosts auth",
+ type);
+ }
+ /*
+ * Try .rhosts or /etc/hosts.equiv authentication with RSA host
+ * authentication.
+ */
+ if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
+ options.rhosts_rsa_authentication && host_key_valid) {
+ if (try_rhosts_rsa_authentication(local_user, own_host_key))
+ return;
+ }
+ /* Try RSA authentication if the server supports it. */
+ if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
+ options.rsa_authentication) {
+ /*
+ * Try RSA authentication using the authentication agent. The
+ * agent is tried first because no passphrase is needed for
+ * it, whereas identity files may require passphrases.
+ */
+ if (try_agent_authentication())
+ return;
+
+ /* Try RSA authentication for each identity. */
+ for (i = 0; i < options.num_identity_files; i++)
+ if (try_rsa_authentication(options.identity_files[i]))
+ return;
+ }
+ /* Try skey authentication if the server supports it. */
+ if ((supported_authentications & (1 << SSH_AUTH_TIS)) &&
+ options.skey_authentication && !options.batch_mode) {
+ if (try_skey_authentication())
+ return;
+ }
+ /* Try password authentication if the server supports it. */
+ if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
+ options.password_authentication && !options.batch_mode) {
+ char prompt[80];
+
+ snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
+ server_user, host);
+ if (try_password_authentication(prompt))
+ return;
+ }
+ /* All authentication methods have failed. Exit with an error message. */
+ fatal("Permission denied.");
+ /* NOTREACHED */
+}