- dugsong@cvs.openbsd.org 2001/06/26 16:15:25
[auth1.c auth.h auth-krb4.c auth-passwd.c readconf.c readconf.h
servconf.c servconf.h session.c sshconnect1.c sshd.c]
Kerberos v5 support for SSH1, mostly from Assar Westerlund
<assar@freebsd.org> and Bjorn Gronvall <bg@sics.se>. markus@ ok
diff --git a/sshconnect1.c b/sshconnect1.c
index ec0a5c9..09203d7 100644
--- a/sshconnect1.c
+++ b/sshconnect1.c
@@ -13,7 +13,7 @@
*/
#include "includes.h"
-RCSID("$OpenBSD: sshconnect1.c,v 1.36 2001/06/23 22:37:46 markus Exp $");
+RCSID("$OpenBSD: sshconnect1.c,v 1.37 2001/06/26 16:15:24 dugsong Exp $");
#include <openssl/bn.h>
#include <openssl/evp.h>
@@ -21,6 +21,9 @@
#ifdef KRB4
#include <krb.h>
#endif
+#ifdef KRB5
+#include <krb5.h>
+#endif
#ifdef AFS
#include <kafs.h>
#include "radix.h"
@@ -43,6 +46,7 @@
#include "readpass.h"
#include "cipher.h"
#include "canohost.h"
+#include "auth.h"
/* Session id for the current session. */
u_char session_id[16];
@@ -379,7 +383,7 @@
#ifdef KRB4
static int
-try_kerberos_authentication(void)
+try_krb4_authentication(void)
{
KTEXT_ST auth; /* Kerberos data */
char *reply;
@@ -397,20 +401,21 @@
/* 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(1)), INST_SZ);
-
- realm = (char *) krb_realmofhost(get_canonical_hostname(1));
+
+ strlcpy(inst, (char *)krb_get_phost(get_canonical_hostname(1)),
+ INST_SZ);
+
+ realm = (char *)krb_realmofhost(get_canonical_hostname(1));
if (!realm) {
- debug("Kerberos V4: no realm for %s", get_canonical_hostname(1));
+ debug("Kerberos v4: no realm for %s", get_canonical_hostname(1));
return 0;
}
/* This can really be anything. */
- checksum = (u_long) getpid();
-
+ 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]);
+ debug("Kerberos v4 krb_mk_req failed: %s", krb_err_txt[r]);
return 0;
}
/* Get session key to decrypt the server's reply with. */
@@ -420,26 +425,26 @@
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)
+ (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) {
+ (struct sockaddr *)&foreign, &slen) < 0) {
debug("getpeername failed: %s", strerror(errno));
fatal_cleanup();
}
@@ -448,96 +453,288 @@
switch (type) {
case SSH_SMSG_FAILURE:
/* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
- debug("Kerberos V4 authentication failed.");
+ debug("Kerberos v4 authentication failed.");
return 0;
break;
-
+
case SSH_SMSG_AUTH_KERBEROS_RESPONSE:
/* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
- debug("Kerberos V4 authentication accepted.");
-
+ debug("Kerberos v4 authentication accepted.");
+
/* Get server's response. */
reply = packet_get_string((u_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);
+ &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!");
+ 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));
+ 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.");
+ debug("Kerberos v4 challenge successful.");
return 1;
} else
- packet_disconnect("Kerberos V4 challenge failed!");
+ packet_disconnect("Kerberos v4 challenge failed!");
break;
-
+
default:
- packet_disconnect("Protocol error on Kerberos V4 response: %d", type);
+ packet_disconnect("Protocol error on Kerberos v4 response: %d", type);
}
return 0;
}
#endif /* KRB4 */
-#ifdef AFS
+#ifdef KRB5
static int
-send_kerberos_tgt(void)
+try_krb5_authentication(krb5_context *context, krb5_auth_context *auth_context)
+{
+ krb5_error_code problem;
+ const char *tkfile;
+ struct stat buf;
+ krb5_ccache ccache = NULL;
+ const char *remotehost;
+ krb5_data ap;
+ int type, payload_len;
+ krb5_ap_rep_enc_part *reply = NULL;
+ int ret;
+
+ memset(&ap, 0, sizeof(ap));
+
+ problem = krb5_init_context(context);
+ if (problem) {
+ debug("Kerberos v5: krb5_init_context failed");
+ ret = 0;
+ goto out;
+ }
+
+ tkfile = krb5_cc_default_name(*context);
+ if (strncmp(tkfile, "FILE:", 5) == 0)
+ tkfile += 5;
+
+ if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) {
+ debug("Kerberos v5: could not get default ccache (permission denied).");
+ ret = 0;
+ goto out;
+ }
+
+ problem = krb5_cc_default(*context, &ccache);
+ if (problem) {
+ debug("Kerberos v5: krb5_cc_default failed: %s",
+ krb5_get_err_text(*context, problem));
+ ret = 0;
+ goto out;
+ }
+
+ remotehost = get_canonical_hostname(1);
+
+ problem = krb5_mk_req(*context, auth_context, AP_OPTS_MUTUAL_REQUIRED,
+ "host", remotehost, NULL, ccache, &ap);
+ if (problem) {
+ debug("Kerberos v5: krb5_mk_req failed: %s",
+ krb5_get_err_text(*context, problem));
+ ret = 0;
+ goto out;
+ }
+
+ packet_start(SSH_CMSG_AUTH_KERBEROS);
+ packet_put_string((char *) ap.data, ap.length);
+ packet_send();
+ packet_write_wait();
+
+ xfree(ap.data);
+ ap.length = 0;
+
+ type = packet_read(&payload_len);
+ switch (type) {
+ case SSH_SMSG_FAILURE:
+ /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
+ debug("Kerberos v5 authentication failed.");
+ ret = 0;
+ break;
+
+ case SSH_SMSG_AUTH_KERBEROS_RESPONSE:
+ /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
+ debug("Kerberos v5 authentication accepted.");
+
+ /* Get server's response. */
+ ap.data = packet_get_string((unsigned int *) &ap.length);
+
+ packet_integrity_check(payload_len, 4 + ap.length, type);
+ /* XXX je to dobre? */
+
+ problem = krb5_rd_rep(*context, *auth_context, &ap, &reply);
+ if (problem) {
+ ret = 0;
+ }
+ ret = 1;
+ break;
+
+ default:
+ packet_disconnect("Protocol error on Kerberos v5 response: %d",
+ type);
+ ret = 0;
+ break;
+
+ }
+
+ out:
+ if (ccache != NULL)
+ krb5_cc_close(*context, ccache);
+ if (reply != NULL)
+ krb5_free_ap_rep_enc_part(*context, reply);
+ if (ap.length > 0)
+ krb5_data_free(&ap);
+
+ return (ret);
+}
+
+static void
+send_krb5_tgt(krb5_context context, krb5_auth_context auth_context)
+{
+ int fd, type, payload_len;
+ krb5_error_code problem;
+ krb5_data outbuf;
+ krb5_ccache ccache = NULL;
+ krb5_creds creds;
+ krb5_kdc_flags flags;
+ const char *remotehost;
+
+ memset(&creds, 0, sizeof(creds));
+ memset(&outbuf, 0, sizeof(outbuf));
+
+ fd = packet_get_connection_in();
+
+ problem = krb5_auth_con_setaddrs_from_fd(context, auth_context, &fd);
+ if (problem)
+ goto out;
+
+ problem = krb5_cc_default(context, &ccache);
+ if (problem)
+ goto out;
+
+ problem = krb5_cc_get_principal(context, ccache, &creds.client);
+ if (problem)
+ goto out;
+
+ problem = krb5_build_principal(context, &creds.server,
+ strlen(creds.client->realm), creds.client->realm,
+ "krbtgt", creds.client->realm, NULL);
+ if (problem)
+ goto out;
+
+ creds.times.endtime = 0;
+
+ flags.i = 0;
+ flags.b.forwarded = 1;
+ flags.b.forwardable = krb5_config_get_bool(context, NULL,
+ "libdefaults", "forwardable", NULL);
+
+ remotehost = get_canonical_hostname(1);
+
+ problem = krb5_get_forwarded_creds(context, auth_context,
+ ccache, flags.i, remotehost, &creds, &outbuf);
+ if (problem)
+ goto out;
+
+ packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
+ packet_put_string((char *)outbuf.data, outbuf.length);
+ packet_send();
+ packet_write_wait();
+
+ type = packet_read(&payload_len);
+
+ if (type == SSH_SMSG_SUCCESS) {
+ char *pname;
+
+ krb5_unparse_name(context, creds.client, &pname);
+ debug("Kerberos v5 TGT forwarded (%s).", pname);
+ xfree(pname);
+ } else
+ debug("Kerberos v5 TGT forwarding failed.");
+
+ return;
+
+ out:
+ if (problem)
+ debug("Kerberos v5 TGT forwarding failed: %s",
+ krb5_get_err_text(context, problem));
+ if (creds.client)
+ krb5_free_principal(context, creds.client);
+ if (creds.server)
+ krb5_free_principal(context, creds.server);
+ if (ccache)
+ krb5_cc_close(context, ccache);
+ if (outbuf.data)
+ xfree(outbuf.data);
+}
+#endif /* KRB5 */
+
+#ifdef AFS
+static void
+send_krb4_tgt(void)
{
CREDENTIALS *creds;
- char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
- int r, type, plen;
- char buffer[8192];
struct stat st;
-
+ char buffer[4096], pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ];
+ int problem, type, len;
+
/* Don't do anything if we don't have any tickets. */
if (stat(tkt_string(), &st) < 0)
- return 0;
-
+ return;
+
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;
- }
+
+ problem = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm);
+ if (problem)
+ goto out;
+
+ problem = krb_get_cred("krbtgt", prealm, prealm, creds);
+ if (problem)
+ goto out;
+
if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) {
- debug("Kerberos V4 ticket expired: %s", TKT_FILE);
- return 0;
+ problem = RD_AP_EXP;
+ goto out;
}
- creds_to_radix(creds, (u_char *)buffer, sizeof buffer);
- xfree(creds);
-
+ creds_to_radix(creds, (u_char *)buffer, sizeof(buffer));
+
packet_start(SSH_CMSG_HAVE_KERBEROS_TGT);
packet_put_cstring(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;
+
+ type = packet_read(&len);
+
+ if (type == SSH_SMSG_SUCCESS)
+ debug("Kerberos v4 TGT forwarded (%s%s%s@%s).",
+ creds->pname, creds->pinst[0] ? "." : "",
+ creds->pinst, creds->realm);
+ else
+ debug("Kerberos v4 TGT rejected.");
+
+ xfree(creds);
+ return;
+
+ out:
+ debug("Kerberos v4 TGT passing failed: %s", krb_err_txt[problem]);
+ xfree(creds);
}
static void
@@ -546,10 +743,10 @@
CREDENTIALS creds;
struct ViceIoctl parms;
struct ClearToken ct;
- int i, type, len, plen;
+ int i, type, len;
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;
@@ -559,7 +756,7 @@
if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0)
break;
p = buf;
-
+
/* Get secret token. */
memcpy(&creds.ticket_st.length, p, sizeof(u_int));
if (creds.ticket_st.length > MAX_KTXT_LEN)
@@ -567,7 +764,7 @@
p += sizeof(u_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))
@@ -577,20 +774,22 @@
p += len;
p += sizeof(len); /* primary flag */
server_cell = p;
-
+
/* Flesh out our credentials. */
- strlcpy(creds.service, "afs", sizeof creds.service);
+ 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.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, (u_char *) buffer, sizeof buffer) <= 0)
+ if (creds_to_radix(&creds, (u_char *)buffer,
+ sizeof(buffer)) <= 0)
break;
packet_start(SSH_CMSG_HAVE_AFS_TOKEN);
packet_put_cstring(buffer);
@@ -599,8 +798,8 @@
/* Roger, Roger. Clearance, Clarence. What's your vector,
Victor? */
- type = packet_read(&plen);
-
+ type = packet_read(&len);
+
if (type == SSH_SMSG_FAILURE)
debug("AFS token for cell %s rejected.", server_cell);
else if (type != SSH_SMSG_SUCCESS)
@@ -622,9 +821,9 @@
u_int clen;
char prompt[1024];
char *challenge, *response;
-
+
debug("Doing challenge reponse authentication.");
-
+
for (i = 0; i < options.number_of_password_prompts; i++) {
/* request a challenge */
packet_start(SSH_CMSG_AUTH_TIS);
@@ -913,9 +1112,13 @@
ssh_userauth1(const char *local_user, const char *server_user, char *host,
Key **keys, int nkeys)
{
+#ifdef KRB5
+ krb5_context context = NULL;
+ krb5_auth_context auth_context = NULL;
+#endif
int i, type;
int payload_len;
-
+
if (supported_authentications == 0)
fatal("ssh_userauth1: server supports no auth methods");
@@ -934,43 +1137,40 @@
/* check whether the connection was accepted without authentication. */
if (type == SSH_SMSG_SUCCESS)
- return;
+ goto success;
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();
+ packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", type);
+
+#ifdef KRB5
+ if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) &&
+ options.kerberos_authentication) {
+ debug("Trying Kerberos v5 authentication.");
+
+ if (try_krb5_authentication(&context, &auth_context)) {
+ type = packet_read(&payload_len);
+ if (type == SSH_SMSG_SUCCESS)
+ goto success;
+ if (type != SSH_SMSG_FAILURE)
+ packet_disconnect("Protocol error: got %d in response to Kerberos v5 auth", type);
+ }
}
- /* 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 */
-
+#endif /* KRB5 */
+
#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. */
+ debug("Trying Kerberos v4 authentication.");
+
+ if (try_krb4_authentication()) {
type = packet_read(&payload_len);
if (type == SSH_SMSG_SUCCESS)
- return;
+ goto success;
if (type != SSH_SMSG_FAILURE)
- packet_disconnect("Protocol error: got %d in response to Kerberos auth", type);
+ packet_disconnect("Protocol error: got %d in response to Kerberos v4 auth", type);
}
}
#endif /* KRB4 */
-
+
/*
* Use rhosts authentication if running in privileged socket and we
* do not wish to remain anonymous.
@@ -986,7 +1186,7 @@
/* The server should respond with success or failure. */
type = packet_read(&payload_len);
if (type == SSH_SMSG_SUCCESS)
- return;
+ goto success;
if (type != SSH_SMSG_FAILURE)
packet_disconnect("Protocol error: got %d in response to rhosts auth",
type);
@@ -1000,7 +1200,7 @@
for (i = 0; i < nkeys; i++) {
if (keys[i] != NULL && keys[i]->type == KEY_RSA1 &&
try_rhosts_rsa_authentication(local_user, keys[i]))
- return;
+ goto success;
}
}
/* Try RSA authentication if the server supports it. */
@@ -1012,20 +1212,20 @@
* it, whereas identity files may require passphrases.
*/
if (try_agent_authentication())
- return;
+ goto success;
/* Try RSA authentication for each identity. */
for (i = 0; i < options.num_identity_files; i++)
if (options.identity_keys[i] != NULL &&
options.identity_keys[i]->type == KEY_RSA1 &&
try_rsa_authentication(options.identity_files[i]))
- return;
+ goto success;
}
/* Try challenge response authentication if the server supports it. */
if ((supported_authentications & (1 << SSH_AUTH_TIS)) &&
options.challenge_response_authentication && !options.batch_mode) {
if (try_challenge_response_authentication())
- return;
+ goto success;
}
/* Try password authentication if the server supports it. */
if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
@@ -1035,9 +1235,41 @@
snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
server_user, host);
if (try_password_authentication(prompt))
- return;
+ goto success;
}
/* All authentication methods have failed. Exit with an error message. */
fatal("Permission denied.");
/* NOTREACHED */
+
+ success:
+#ifdef KRB5
+ /* Try Kerberos v5 TGT passing. */
+ if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) &&
+ options.kerberos_tgt_passing && context && auth_context) {
+ if (options.cipher == SSH_CIPHER_NONE)
+ log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!");
+ send_krb5_tgt(context, auth_context);
+ }
+ if (auth_context)
+ krb5_auth_con_free(context, auth_context);
+ if (context)
+ krb5_free_context(context);
+#endif
+
+#ifdef AFS
+ /* Try Kerberos v4 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!");
+ send_krb4_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 */
}