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GSSAPI key exchange support 

This patch has been rejected upstream: "None of the OpenSSH developers are
in favour of adding this, and this situation has not changed for several
years.  This is not a slight on Simon's patch, which is of fine quality, but
just that a) we don't trust GSSAPI implementations that much and b) we don't
like adding new KEX since they are pre-auth attack surface.  This one is
particularly scary, since it requires hooks out to typically root-owned
system resources."

However, quite a lot of people rely on this in Debian, and it's better to
have it merged into the main openssh package rather than having separate
-krb5 packages (as we used to have).  It seems to have a generally good
security history.

Origin: other, https://github.com/openssh-gsskex/openssh-gsskex/commits/debian/master
Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1242
Last-Updated: 2020-02-21

Patch-Name: gssapi.patch

Gbp-Pq: Name gssapi.patch
This commit is contained in:
Simon Wilkinson 2014-02-09 16:09:48 +00:00 committed by Lu zhiping
parent 619b31ff1d
commit 1a20caf1c8
38 changed files with 2625 additions and 161 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Makefile.in
View File

@ -109,6 +109,7 @@ LIBSSH_OBJS=${LIBOPENSSH_OBJS} \
kex.o kexdh.o kexgex.o kexecdh.o kexc25519.o \
kexgexc.o kexgexs.o \
sntrup4591761.o kexsntrup4591761x25519.o kexgen.o \
kexgssc.o \
sftp-realpath.o platform-pledge.o platform-tracing.o platform-misc.o \
sshbuf-io.o
@ -125,7 +126,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o \
auth-bsdauth.o auth2-hostbased.o auth2-kbdint.o \
auth2-none.o auth2-passwd.o auth2-pubkey.o \
monitor.o monitor_wrap.o auth-krb5.o \
auth2-gss.o gss-serv.o gss-serv-krb5.o \
auth2-gss.o gss-serv.o gss-serv-krb5.o kexgsss.o \
loginrec.o auth-pam.o auth-shadow.o auth-sia.o md5crypt.o \
sftp-server.o sftp-common.o \
sandbox-null.o sandbox-rlimit.o sandbox-systrace.o sandbox-darwin.o \

33
README.md
View File

@ -1,3 +1,36 @@
Portable OpenSSH with GSSAPI Key Exchange patches
=================================================
Currently, there are two branches with gssapi key exchange related
patches:
* fedora/master: Changes that are shipped in Fedora
* debian/master: Changes that are shipped in Debian
The target is to converge to a shared repository with single master
branch from where we could build releases for both OSes.
What is in:
* The original patch implementing missing parts of RFC4462 by Simon Wilkinson
adapted to the current OpenSSH versions and with several fixes
* New methods for GSSAPI Kex from IETF draft [1] from Jakub Jelen
Missing kerberos-related parts:
* .k5login and .kusers support available in Fedora [2] [3].
* Improved handling of kerberos ccache location [4]
[1] https://tools.ietf.org/html/draft-ietf-curdle-gss-keyex-sha2-08
[2] https://src.fedoraproject.org/rpms/openssh/blob/master/f/openssh-6.6p1-kuserok.patch
[3] https://src.fedoraproject.org/rpms/openssh/blob/master/f/openssh-6.6p1-GSSAPIEnablek5users.patch
[4] https://bugzilla.mindrot.org/show_bug.cgi?id=2775
-------------------------------------------------------------------------------
# Portable OpenSSH
[![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/openssh.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:openssh)

96
auth.c
View File

@ -400,7 +400,8 @@ auth_root_allowed(struct ssh *ssh, const char *method)
case PERMIT_NO_PASSWD:
if (strcmp(method, "publickey") == 0 ||
strcmp(method, "hostbased") == 0 ||
strcmp(method, "gssapi-with-mic") == 0)
strcmp(method, "gssapi-with-mic") == 0 ||
strcmp(method, "gssapi-keyex") == 0)
return 1;
break;
case PERMIT_FORCED_ONLY:
@ -724,99 +725,6 @@ fakepw(void)
return (&fake);
}
/*
* Returns the remote DNS hostname as a string. The returned string must not
* be freed. NB. this will usually trigger a DNS query the first time it is
* called.
* This function does additional checks on the hostname to mitigate some
* attacks on legacy rhosts-style authentication.
* XXX is RhostsRSAAuthentication vulnerable to these?
* XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
*/
static char *
remote_hostname(struct ssh *ssh)
{
struct sockaddr_storage from;
socklen_t fromlen;
struct addrinfo hints, *ai, *aitop;
char name[NI_MAXHOST], ntop2[NI_MAXHOST];
const char *ntop = ssh_remote_ipaddr(ssh);
/* Get IP address of client. */
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
if (getpeername(ssh_packet_get_connection_in(ssh),
(struct sockaddr *)&from, &fromlen) == -1) {
debug("getpeername failed: %.100s", strerror(errno));
return xstrdup(ntop);
}
ipv64_normalise_mapped(&from, &fromlen);
if (from.ss_family == AF_INET6)
fromlen = sizeof(struct sockaddr_in6);
debug3("Trying to reverse map address %.100s.", ntop);
/* Map the IP address to a host name. */
if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
NULL, 0, NI_NAMEREQD) != 0) {
/* Host name not found. Use ip address. */
return xstrdup(ntop);
}
/*
* if reverse lookup result looks like a numeric hostname,
* someone is trying to trick us by PTR record like following:
* 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
*/
memset(&hints, 0, sizeof(hints));
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
hints.ai_flags = AI_NUMERICHOST;
if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
name, ntop);
freeaddrinfo(ai);
return xstrdup(ntop);
}
/* Names are stored in lowercase. */
lowercase(name);
/*
* Map it back to an IP address and check that the given
* address actually is an address of this host. This is
* necessary because anyone with access to a name server can
* define arbitrary names for an IP address. Mapping from
* name to IP address can be trusted better (but can still be
* fooled if the intruder has access to the name server of
* the domain).
*/
memset(&hints, 0, sizeof(hints));
hints.ai_family = from.ss_family;
hints.ai_socktype = SOCK_STREAM;
if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
logit("reverse mapping checking getaddrinfo for %.700s "
"[%s] failed.", name, ntop);
return xstrdup(ntop);
}
/* Look for the address from the list of addresses. */
for (ai = aitop; ai; ai = ai->ai_next) {
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
(strcmp(ntop, ntop2) == 0))
break;
}
freeaddrinfo(aitop);
/* If we reached the end of the list, the address was not there. */
if (ai == NULL) {
/* Address not found for the host name. */
logit("Address %.100s maps to %.600s, but this does not "
"map back to the address.", ntop, name);
return xstrdup(ntop);
}
return xstrdup(name);
}
/*
* Return the canonical name of the host in the other side of the current
* connection. The host name is cached, so it is efficient to call this

56
auth2-gss.c
View File

@ -1,7 +1,7 @@
/* $OpenBSD: auth2-gss.c,v 1.29 2018/07/31 03:10:27 djm Exp $ */
/*
* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
* Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -54,6 +54,48 @@ static int input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh);
static int input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh);
static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
/*
* The 'gssapi_keyex' userauth mechanism.
*/
static int
userauth_gsskeyex(struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
int r, authenticated = 0;
struct sshbuf *b = NULL;
gss_buffer_desc mic, gssbuf;
u_char *p;
size_t len;
if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("%s: %s", __func__, ssh_err(r));
if ((b = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
mic.value = p;
mic.length = len;
ssh_gssapi_buildmic(b, authctxt->user, authctxt->service,
"gssapi-keyex");
if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
fatal("%s: sshbuf_mutable_ptr failed", __func__);
gssbuf.length = sshbuf_len(b);
/* gss_kex_context is NULL with privsep, so we can't check it here */
if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
&gssbuf, &mic))))
authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
authctxt->pw, 1));
sshbuf_free(b);
free(mic.value);
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)
@ -260,7 +302,8 @@ input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh)
if ((r = sshpkt_get_end(ssh)) != 0)
fatal("%s: %s", __func__, ssh_err(r));
authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
authctxt->pw, 1));
if ((!use_privsep || mm_is_monitor()) &&
(displayname = ssh_gssapi_displayname()) != NULL)
@ -306,7 +349,8 @@ input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh)
gssbuf.length = sshbuf_len(b);
if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
authctxt->pw, 0));
else
logit("GSSAPI MIC check failed");
@ -326,6 +370,12 @@ input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh)
return 0;
}
Authmethod method_gsskeyex = {
"gssapi-keyex",
userauth_gsskeyex,
&options.gss_authentication
};
Authmethod method_gssapi = {
"gssapi-with-mic",
userauth_gssapi,

2
auth2.c
View File

@ -73,6 +73,7 @@ extern Authmethod method_passwd;
extern Authmethod method_kbdint;
extern Authmethod method_hostbased;
#ifdef GSSAPI
extern Authmethod method_gsskeyex;
extern Authmethod method_gssapi;
#endif
@ -80,6 +81,7 @@ Authmethod *authmethods[] = {
&method_none,
&method_pubkey,
#ifdef GSSAPI
&method_gsskeyex,
&method_gssapi,
#endif
&method_passwd,

93
canohost.c
View File

@ -35,6 +35,99 @@
#include "canohost.h"
#include "misc.h"
/*
* Returns the remote DNS hostname as a string. The returned string must not
* be freed. NB. this will usually trigger a DNS query the first time it is
* called.
* This function does additional checks on the hostname to mitigate some
* attacks on legacy rhosts-style authentication.
* XXX is RhostsRSAAuthentication vulnerable to these?
* XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
*/
char *
remote_hostname(struct ssh *ssh)
{
struct sockaddr_storage from;
socklen_t fromlen;
struct addrinfo hints, *ai, *aitop;
char name[NI_MAXHOST], ntop2[NI_MAXHOST];
const char *ntop = ssh_remote_ipaddr(ssh);
/* Get IP address of client. */
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
if (getpeername(ssh_packet_get_connection_in(ssh),
(struct sockaddr *)&from, &fromlen) == -1) {
debug("getpeername failed: %.100s", strerror(errno));
return xstrdup(ntop);
}
ipv64_normalise_mapped(&from, &fromlen);
if (from.ss_family == AF_INET6)
fromlen = sizeof(struct sockaddr_in6);
debug3("Trying to reverse map address %.100s.", ntop);
/* Map the IP address to a host name. */
if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
NULL, 0, NI_NAMEREQD) != 0) {
/* Host name not found. Use ip address. */
return xstrdup(ntop);
}
/*
* if reverse lookup result looks like a numeric hostname,
* someone is trying to trick us by PTR record like following:
* 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
*/
memset(&hints, 0, sizeof(hints));
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
hints.ai_flags = AI_NUMERICHOST;
if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
name, ntop);
freeaddrinfo(ai);
return xstrdup(ntop);
}
/* Names are stored in lowercase. */
lowercase(name);
/*
* Map it back to an IP address and check that the given
* address actually is an address of this host. This is
* necessary because anyone with access to a name server can
* define arbitrary names for an IP address. Mapping from
* name to IP address can be trusted better (but can still be
* fooled if the intruder has access to the name server of
* the domain).
*/
memset(&hints, 0, sizeof(hints));
hints.ai_family = from.ss_family;
hints.ai_socktype = SOCK_STREAM;
if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
logit("reverse mapping checking getaddrinfo for %.700s "
"[%s] failed.", name, ntop);
return xstrdup(ntop);
}
/* Look for the address from the list of addresses. */
for (ai = aitop; ai; ai = ai->ai_next) {
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
(strcmp(ntop, ntop2) == 0))
break;
}
freeaddrinfo(aitop);
/* If we reached the end of the list, the address was not there. */
if (ai == NULL) {
/* Address not found for the host name. */
logit("Address %.100s maps to %.600s, but this does not "
"map back to the address.", ntop, name);
return xstrdup(ntop);
}
return xstrdup(name);
}
void
ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len)
{

3
canohost.h
View File

@ -15,6 +15,9 @@
#ifndef _CANOHOST_H
#define _CANOHOST_H
struct ssh;
char *remote_hostname(struct ssh *);
char *get_peer_ipaddr(int);
int get_peer_port(int);
char *get_local_ipaddr(int);

15
clientloop.c
View File

@ -112,6 +112,10 @@
#include "ssherr.h"
#include "hostfile.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
/* import options */
extern Options options;
@ -1379,9 +1383,18 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
break;
/* Do channel operations unless rekeying in progress. */
if (!ssh_packet_is_rekeying(ssh))
if (!ssh_packet_is_rekeying(ssh)) {
channel_after_select(ssh, readset, writeset);
#ifdef GSSAPI
if (options.gss_renewal_rekey &&
ssh_gssapi_credentials_updated(NULL)) {
debug("credentials updated - forcing rekey");
need_rekeying = 1;
}
#endif
}
/* Buffer input from the connection. */
client_process_net_input(ssh, readset);

24
configure.ac
View File

@ -674,6 +674,30 @@ main() { if (NSVersionOfRunTimeLibrary("System") >= (60 << 16))
[Use tunnel device compatibility to OpenBSD])
AC_DEFINE([SSH_TUN_PREPEND_AF], [1],
[Prepend the address family to IP tunnel traffic])
AC_MSG_CHECKING([if we have the Security Authorization Session API])
AC_TRY_COMPILE([#include <Security/AuthSession.h>],
[SessionCreate(0, 0);],
[ac_cv_use_security_session_api="yes"
AC_DEFINE([USE_SECURITY_SESSION_API], [1],
[platform has the Security Authorization Session API])
LIBS="$LIBS -framework Security"
AC_MSG_RESULT([yes])],
[ac_cv_use_security_session_api="no"
AC_MSG_RESULT([no])])
AC_MSG_CHECKING([if we have an in-memory credentials cache])
AC_TRY_COMPILE(
[#include <Kerberos/Kerberos.h>],
[cc_context_t c;
(void) cc_initialize (&c, 0, NULL, NULL);],
[AC_DEFINE([USE_CCAPI], [1],
[platform uses an in-memory credentials cache])
LIBS="$LIBS -framework Security"
AC_MSG_RESULT([yes])
if test "x$ac_cv_use_security_session_api" = "xno"; then
AC_MSG_ERROR([*** Need a security framework to use the credentials cache API ***])
fi],
[AC_MSG_RESULT([no])]
)
m4_pattern_allow([AU_IPv])
AC_CHECK_DECL([AU_IPv4], [],
AC_DEFINE([AU_IPv4], [0], [System only supports IPv4 audit records])

300
gss-genr.c
View File

@ -1,7 +1,7 @@
/* $OpenBSD: gss-genr.c,v 1.26 2018/07/10 09:13:30 djm Exp $ */
/*
* Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
* Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -41,12 +41,36 @@
#include "sshbuf.h"
#include "log.h"
#include "ssh2.h"
#include "cipher.h"
#include "sshkey.h"
#include "kex.h"
#include "digest.h"
#include "packet.h"
#include "ssh-gss.h"
extern u_char *session_id2;
extern u_int session_id2_len;
typedef struct {
char *encoded;
gss_OID oid;
} ssh_gss_kex_mapping;
/*
* XXX - It would be nice to find a more elegant way of handling the
* XXX passing of the key exchange context to the userauth routines
*/
Gssctxt *gss_kex_context = NULL;
static ssh_gss_kex_mapping *gss_enc2oid = NULL;
int
ssh_gssapi_oid_table_ok(void) {
return (gss_enc2oid != NULL);
}
/* sshbuf_get for gss_buffer_desc */
int
ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g)
@ -62,6 +86,162 @@ ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g)
return 0;
}
/* sshpkt_get of gss_buffer_desc */
int
ssh_gssapi_sshpkt_get_buffer_desc(struct ssh *ssh, gss_buffer_desc *g)
{
int r;
u_char *p;
size_t len;
if ((r = sshpkt_get_string(ssh, &p, &len)) != 0)
return r;
g->value = p;
g->length = len;
return 0;
}
/*
* Return a list of the gss-group1-sha1 mechanisms supported by this program
*
* We test mechanisms to ensure that we can use them, to avoid starting
* a key exchange with a bad mechanism
*/
char *
ssh_gssapi_client_mechanisms(const char *host, const char *client,
const char *kex) {
gss_OID_set gss_supported = NULL;
OM_uint32 min_status;
if (GSS_ERROR(gss_indicate_mechs(&min_status, &gss_supported)))
return NULL;
return ssh_gssapi_kex_mechs(gss_supported, ssh_gssapi_check_mechanism,
host, client, kex);
}
char *
ssh_gssapi_kex_mechs(gss_OID_set gss_supported, ssh_gssapi_check_fn *check,
const char *host, const char *client, const char *kex) {
struct sshbuf *buf = NULL;
size_t i;
int r = SSH_ERR_ALLOC_FAIL;
int oidpos, enclen;
char *mechs, *encoded;
u_char digest[SSH_DIGEST_MAX_LENGTH];
char deroid[2];
struct ssh_digest_ctx *md = NULL;
char *s, *cp, *p;
if (gss_enc2oid != NULL) {
for (i = 0; gss_enc2oid[i].encoded != NULL; i++)
free(gss_enc2oid[i].encoded);
free(gss_enc2oid);
}
gss_enc2oid = xmalloc(sizeof(ssh_gss_kex_mapping) *
(gss_supported->count + 1));
if ((buf = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
oidpos = 0;
s = cp = xstrdup(kex);
for (i = 0; i < gss_supported->count; i++) {
if (gss_supported->elements[i].length < 128 &&
(*check)(NULL, &(gss_supported->elements[i]), host, client)) {
deroid[0] = SSH_GSS_OIDTYPE;
deroid[1] = gss_supported->elements[i].length;
if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
(r = ssh_digest_update(md, deroid, 2)) != 0 ||
(r = ssh_digest_update(md,
gss_supported->elements[i].elements,
gss_supported->elements[i].length)) != 0 ||
(r = ssh_digest_final(md, digest, sizeof(digest))) != 0)
fatal("%s: digest failed: %s", __func__,
ssh_err(r));
ssh_digest_free(md);
md = NULL;
encoded = xmalloc(ssh_digest_bytes(SSH_DIGEST_MD5)
* 2);
enclen = __b64_ntop(digest,
ssh_digest_bytes(SSH_DIGEST_MD5), encoded,
ssh_digest_bytes(SSH_DIGEST_MD5) * 2);
cp = strncpy(s, kex, strlen(kex));
for ((p = strsep(&cp, ",")); p && *p != '\0';
(p = strsep(&cp, ","))) {
if (sshbuf_len(buf) != 0 &&
(r = sshbuf_put_u8(buf, ',')) != 0)
fatal("%s: sshbuf_put_u8 error: %s",
__func__, ssh_err(r));
if ((r = sshbuf_put(buf, p, strlen(p))) != 0 ||
(r = sshbuf_put(buf, encoded, enclen)) != 0)
fatal("%s: sshbuf_put error: %s",
__func__, ssh_err(r));
}
gss_enc2oid[oidpos].oid = &(gss_supported->elements[i]);
gss_enc2oid[oidpos].encoded = encoded;
oidpos++;
}
}
free(s);
gss_enc2oid[oidpos].oid = NULL;
gss_enc2oid[oidpos].encoded = NULL;
if ((mechs = sshbuf_dup_string(buf)) == NULL)
fatal("%s: sshbuf_dup_string failed", __func__);
sshbuf_free(buf);
if (strlen(mechs) == 0) {
free(mechs);
mechs = NULL;
}
return (mechs);
}
gss_OID
ssh_gssapi_id_kex(Gssctxt *ctx, char *name, int kex_type) {
int i = 0;
#define SKIP_KEX_NAME(type) \
case type: \
if (strlen(name) < sizeof(type##_ID)) \
return GSS_C_NO_OID; \
name += sizeof(type##_ID) - 1; \
break;
switch (kex_type) {
SKIP_KEX_NAME(KEX_GSS_GRP1_SHA1)
SKIP_KEX_NAME(KEX_GSS_GRP14_SHA1)
SKIP_KEX_NAME(KEX_GSS_GRP14_SHA256)
SKIP_KEX_NAME(KEX_GSS_GRP16_SHA512)
SKIP_KEX_NAME(KEX_GSS_GEX_SHA1)
SKIP_KEX_NAME(KEX_GSS_NISTP256_SHA256)
SKIP_KEX_NAME(KEX_GSS_C25519_SHA256)
default:
return GSS_C_NO_OID;
}
#undef SKIP_KEX_NAME
while (gss_enc2oid[i].encoded != NULL &&
strcmp(name, gss_enc2oid[i].encoded) != 0)
i++;
if (gss_enc2oid[i].oid != NULL && ctx != NULL)
ssh_gssapi_set_oid(ctx, gss_enc2oid[i].oid);
return gss_enc2oid[i].oid;
}
/* Check that the OID in a data stream matches that in the context */
int
ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
@ -218,7 +398,7 @@ ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
}
ctx->major = gss_init_sec_context(&ctx->minor,
GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
ctx->client_creds, &ctx->context, ctx->name, ctx->oid,
GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
0, NULL, recv_tok, NULL, send_tok, flags, NULL);
@ -247,9 +427,43 @@ ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
return (ctx->major);
}
OM_uint32
ssh_gssapi_client_identity(Gssctxt *ctx, const char *name)
{
gss_buffer_desc gssbuf;
gss_name_t gssname;
OM_uint32 status;
gss_OID_set oidset;
gssbuf.value = (void *) name;
gssbuf.length = strlen(gssbuf.value);
gss_create_empty_oid_set(&status, &oidset);
gss_add_oid_set_member(&status, ctx->oid, &oidset);
ctx->major = gss_import_name(&ctx->minor, &gssbuf,
GSS_C_NT_USER_NAME, &gssname);
if (!ctx->major)
ctx->major = gss_acquire_cred(&ctx->minor,
gssname, 0, oidset, GSS_C_INITIATE,
&ctx->client_creds, NULL, NULL);
gss_release_name(&status, &gssname);
gss_release_oid_set(&status, &oidset);
if (ctx->major)
ssh_gssapi_error(ctx);
return(ctx->major);
}
OM_uint32
ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
{
if (ctx == NULL)
return -1;
if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
GSS_C_QOP_DEFAULT, buffer, hash)))
ssh_gssapi_error(ctx);
@ -257,6 +471,19 @@ ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
return (ctx->major);
}
/* Priviledged when used by server */
OM_uint32
ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
{
if (ctx == NULL)
return -1;
ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
gssbuf, gssmic, NULL);
return (ctx->major);
}
void
ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service,
const char *context)
@ -273,11 +500,16 @@ ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service,
}
int
ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host,
const char *client)
{
gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
OM_uint32 major, minor;
gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"};
Gssctxt *intctx = NULL;
if (ctx == NULL)
ctx = &intctx;
/* RFC 4462 says we MUST NOT do SPNEGO */
if (oid->length == spnego_oid.length &&
@ -287,6 +519,10 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
ssh_gssapi_build_ctx(ctx);
ssh_gssapi_set_oid(*ctx, oid);
major = ssh_gssapi_import_name(*ctx, host);
if (!GSS_ERROR(major) && client)
major = ssh_gssapi_client_identity(*ctx, client);
if (!GSS_ERROR(major)) {
major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token,
NULL);
@ -296,10 +532,66 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
GSS_C_NO_BUFFER);
}
if (GSS_ERROR(major))
if (GSS_ERROR(major) || intctx != NULL)
ssh_gssapi_delete_ctx(ctx);
return (!GSS_ERROR(major));
}
int
ssh_gssapi_credentials_updated(Gssctxt *ctxt) {
static gss_name_t saved_name = GSS_C_NO_NAME;
static OM_uint32 saved_lifetime = 0;
static gss_OID saved_mech = GSS_C_NO_OID;
static gss_name_t name;
static OM_uint32 last_call = 0;
OM_uint32 lifetime, now, major, minor;
int equal;
now = time(NULL);
if (ctxt) {
debug("Rekey has happened - updating saved versions");
if (saved_name != GSS_C_NO_NAME)
gss_release_name(&minor, &saved_name);
major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL,
&saved_name, &saved_lifetime, NULL, NULL);
if (!GSS_ERROR(major)) {
saved_mech = ctxt->oid;
saved_lifetime+= now;
} else {
/* Handle the error */
}
return 0;
}
if (now - last_call < 10)
return 0;
last_call = now;
if (saved_mech == GSS_C_NO_OID)
return 0;
major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL,
&name, &lifetime, NULL, NULL);
if (major == GSS_S_CREDENTIALS_EXPIRED)
return 0;
else if (GSS_ERROR(major))
return 0;
major = gss_compare_name(&minor, saved_name, name, &equal);
gss_release_name(&minor, &name);
if (GSS_ERROR(major))
return 0;
if (equal && (saved_lifetime < lifetime + now - 10))
return 1;
return 0;
}
#endif /* GSSAPI */

85
gss-serv-krb5.c
View File

@ -1,7 +1,7 @@
/* $OpenBSD: gss-serv-krb5.c,v 1.9 2018/07/09 21:37:55 markus Exp $ */
/*
* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
* Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -120,8 +120,8 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
krb5_error_code problem;
krb5_principal princ;
OM_uint32 maj_status, min_status;
int len;
const char *errmsg;
const char *new_ccname;
if (client->creds == NULL) {
debug("No credentials stored");
@ -180,11 +180,16 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
return;
}
client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
new_ccname = krb5_cc_get_name(krb_context, ccache);
client->store.envvar = "KRB5CCNAME";
len = strlen(client->store.filename) + 6;
client->store.envval = xmalloc(len);
snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
#ifdef USE_CCAPI
xasprintf(&client->store.envval, "API:%s", new_ccname);
client->store.filename = NULL;
#else
xasprintf(&client->store.envval, "FILE:%s", new_ccname);
client->store.filename = xstrdup(new_ccname);
#endif
#ifdef USE_PAM
if (options.use_pam)
@ -196,6 +201,71 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
return;
}
int
ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store,
ssh_gssapi_client *client)
{
krb5_ccache ccache = NULL;
krb5_principal principal = NULL;
char *name = NULL;
krb5_error_code problem;
OM_uint32 maj_status, min_status;
if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) {
logit("krb5_cc_resolve(): %.100s",
krb5_get_err_text(krb_context, problem));
return 0;
}
/* Find out who the principal in this cache is */
if ((problem = krb5_cc_get_principal(krb_context, ccache,
&principal))) {
logit("krb5_cc_get_principal(): %.100s",
krb5_get_err_text(krb_context, problem));
krb5_cc_close(krb_context, ccache);
return 0;
}
if ((problem = krb5_unparse_name(krb_context, principal, &name))) {
logit("krb5_unparse_name(): %.100s",
krb5_get_err_text(krb_context, problem));
krb5_free_principal(krb_context, principal);
krb5_cc_close(krb_context, ccache);
return 0;
}
if (strcmp(name,client->exportedname.value)!=0) {
debug("Name in local credentials cache differs. Not storing");
krb5_free_principal(krb_context, principal);
krb5_cc_close(krb_context, ccache);
krb5_free_unparsed_name(krb_context, name);
return 0;
}
krb5_free_unparsed_name(krb_context, name);
/* Name matches, so lets get on with it! */
if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) {
logit("krb5_cc_initialize(): %.100s",
krb5_get_err_text(krb_context, problem));
krb5_free_principal(krb_context, principal);
krb5_cc_close(krb_context, ccache);
return 0;
}
krb5_free_principal(krb_context, principal);
if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds,
ccache))) {
logit("gss_krb5_copy_ccache() failed. Sorry!");
krb5_cc_close(krb_context, ccache);
return 0;
}
return 1;
}
ssh_gssapi_mech gssapi_kerberos_mech = {
"toWM5Slw5Ew8Mqkay+al2g==",
"Kerberos",
@ -203,7 +273,8 @@ ssh_gssapi_mech gssapi_kerberos_mech = {
NULL,
&ssh_gssapi_krb5_userok,
NULL,
&ssh_gssapi_krb5_storecreds
&ssh_gssapi_krb5_storecreds,
&ssh_gssapi_krb5_updatecreds
};
#endif /* KRB5 */

188
gss-serv.c
View File

@ -1,7 +1,7 @@
/* $OpenBSD: gss-serv.c,v 1.31 2018/07/09 21:37:55 markus Exp $ */
/*
* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
* Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -44,17 +44,19 @@
#include "session.h"
#include "misc.h"
#include "servconf.h"
#include "uidswap.h"
#include "ssh-gss.h"
#include "monitor_wrap.h"
extern ServerOptions options;
static ssh_gssapi_client gssapi_client =
{ GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL, NULL}};
{ GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, GSS_C_NO_CREDENTIAL,
GSS_C_NO_NAME, NULL, {NULL, NULL, NULL, NULL, NULL}, 0, 0};
ssh_gssapi_mech gssapi_null_mech =
{ NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
{ NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL, NULL};
#ifdef KRB5
extern ssh_gssapi_mech gssapi_kerberos_mech;
@ -140,6 +142,29 @@ ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
return (ssh_gssapi_acquire_cred(*ctx));
}
/* Unprivileged */
char *
ssh_gssapi_server_mechanisms(void) {
if (supported_oids == NULL)
ssh_gssapi_prepare_supported_oids();
return (ssh_gssapi_kex_mechs(supported_oids,
&ssh_gssapi_server_check_mech, NULL, NULL,
options.gss_kex_algorithms));
}
/* Unprivileged */
int
ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data,
const char *dummy) {
Gssctxt *ctx = NULL;
int res;
res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid)));
ssh_gssapi_delete_ctx(&ctx);
return (res);
}
/* Unprivileged */
void
ssh_gssapi_supported_oids(gss_OID_set *oidset)
@ -150,7 +175,9 @@ ssh_gssapi_supported_oids(gss_OID_set *oidset)
gss_OID_set supported;
gss_create_empty_oid_set(&min_status, oidset);
gss_indicate_mechs(&min_status, &supported);
if (GSS_ERROR(gss_indicate_mechs(&min_status, &supported)))
return;
while (supported_mechs[i]->name != NULL) {
if (GSS_ERROR(gss_test_oid_set_member(&min_status,
@ -276,8 +303,48 @@ OM_uint32
ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
{
int i = 0;
int equal = 0;
gss_name_t new_name = GSS_C_NO_NAME;
gss_buffer_desc ename = GSS_C_EMPTY_BUFFER;
gss_buffer_desc ename;
if (options.gss_store_rekey && client->used && ctx->client_creds) {
if (client->mech->oid.length != ctx->oid->length ||
(memcmp(client->mech->oid.elements,
ctx->oid->elements, ctx->oid->length) !=0)) {
debug("Rekeyed credentials have different mechanism");
return GSS_S_COMPLETE;
}
if ((ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
ctx->client_creds, ctx->oid, &new_name,
NULL, NULL, NULL))) {
ssh_gssapi_error(ctx);
return (ctx->major);
}
ctx->major = gss_compare_name(&ctx->minor, client->name,
new_name, &equal);
if (GSS_ERROR(ctx->major)) {
ssh_gssapi_error(ctx);
return (ctx->major);
}
if (!equal) {
debug("Rekeyed credentials have different name");
return GSS_S_COMPLETE;
}
debug("Marking rekeyed credentials for export");
gss_release_name(&ctx->minor, &client->name);
gss_release_cred(&ctx->minor, &client->creds);
client->name = new_name;
client->creds = ctx->client_creds;
ctx->client_creds = GSS_C_NO_CREDENTIAL;
client->updated = 1;
return GSS_S_COMPLETE;
}
client->mech = NULL;
@ -292,6 +359,13 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
if (client->mech == NULL)
return GSS_S_FAILURE;
if (ctx->client_creds &&
(ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
ctx->client_creds, ctx->oid, &client->name, NULL, NULL, NULL))) {
ssh_gssapi_error(ctx);
return (ctx->major);
}
if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
&client->displayname, NULL))) {
ssh_gssapi_error(ctx);
@ -309,6 +383,8 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
return (ctx->major);
}
gss_release_buffer(&ctx->minor, &ename);
/* We can't copy this structure, so we just move the pointer to it */
client->creds = ctx->client_creds;
ctx->client_creds = GSS_C_NO_CREDENTIAL;
@ -356,19 +432,23 @@ ssh_gssapi_do_child(char ***envp, u_int *envsizep)
/* Privileged */
int
ssh_gssapi_userok(char *user)
ssh_gssapi_userok(char *user, struct passwd *pw, int kex)
{
OM_uint32 lmin;
(void) kex; /* used in privilege separation */
if (gssapi_client.exportedname.length == 0 ||
gssapi_client.exportedname.value == NULL) {
debug("No suitable client data");
return 0;
}
if (gssapi_client.mech && gssapi_client.mech->userok)
if ((*gssapi_client.mech->userok)(&gssapi_client, user))
if ((*gssapi_client.mech->userok)(&gssapi_client, user)) {
gssapi_client.used = 1;
gssapi_client.store.owner = pw;
return 1;
else {
} else {
/* Destroy delegated credentials if userok fails */
gss_release_buffer(&lmin, &gssapi_client.displayname);
gss_release_buffer(&lmin, &gssapi_client.exportedname);
@ -382,14 +462,90 @@ ssh_gssapi_userok(char *user)
return (0);
}
/* Privileged */
OM_uint32
ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
{
ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
gssbuf, gssmic, NULL);
/* These bits are only used for rekeying. The unpriviledged child is running
* as the user, the monitor is root.
*
* In the child, we want to :
* *) Ask the monitor to store our credentials into the store we specify
* *) If it succeeds, maybe do a PAM update
*/
return (ctx->major);
/* Stuff for PAM */
#ifdef USE_PAM
static int ssh_gssapi_simple_conv(int n, const struct pam_message **msg,
struct pam_response **resp, void *data)
{
return (PAM_CONV_ERR);
}
#endif
void
ssh_gssapi_rekey_creds(void) {
int ok;
#ifdef USE_PAM
int ret;
pam_handle_t *pamh = NULL;
struct pam_conv pamconv = {ssh_gssapi_simple_conv, NULL};
char *envstr;
#endif
if (gssapi_client.store.filename == NULL &&
gssapi_client.store.envval == NULL &&
gssapi_client.store.envvar == NULL)
return;
ok = PRIVSEP(ssh_gssapi_update_creds(&gssapi_client.store));
if (!ok)
return;
debug("Rekeyed credentials stored successfully");
/* Actually managing to play with the ssh pam stack from here will
* be next to impossible. In any case, we may want different options
* for rekeying. So, use our own :)
*/
#ifdef USE_PAM
if (!use_privsep) {
debug("Not even going to try and do PAM with privsep disabled");
return;
}
ret = pam_start("sshd-rekey", gssapi_client.store.owner->pw_name,
&pamconv, &pamh);
if (ret)
return;
xasprintf(&envstr, "%s=%s", gssapi_client.store.envvar,
gssapi_client.store.envval);
ret = pam_putenv(pamh, envstr);
if (!ret)
pam_setcred(pamh, PAM_REINITIALIZE_CRED);
pam_end(pamh, PAM_SUCCESS);
#endif
}
int
ssh_gssapi_update_creds(ssh_gssapi_ccache *store) {
int ok = 0;
/* Check we've got credentials to store */
if (!gssapi_client.updated)
return 0;
gssapi_client.updated = 0;
temporarily_use_uid(gssapi_client.store.owner);
if (gssapi_client.mech && gssapi_client.mech->updatecreds)
ok = (*gssapi_client.mech->updatecreds)(store, &gssapi_client);
else
debug("No update function for this mechanism");
restore_uid();
return ok;
}
/* Privileged */

66
kex.c
View File

@ -57,11 +57,16 @@
#include "misc.h"
#include "dispatch.h"
#include "monitor.h"
#include "xmalloc.h"
#include "ssherr.h"
#include "sshbuf.h"
#include "digest.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
/* prototype */
static int kex_choose_conf(struct ssh *);
static int kex_input_newkeys(int, u_int32_t, struct ssh *);
@ -115,15 +120,28 @@ static const struct kexalg kexalgs[] = {
#endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */
{ NULL, 0, -1, -1},
};
static const struct kexalg gss_kexalgs[] = {
#ifdef GSSAPI
{ KEX_GSS_GEX_SHA1_ID, KEX_GSS_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
{ KEX_GSS_GRP1_SHA1_ID, KEX_GSS_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
{ KEX_GSS_GRP14_SHA1_ID, KEX_GSS_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
{ KEX_GSS_GRP14_SHA256_ID, KEX_GSS_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
{ KEX_GSS_GRP16_SHA512_ID, KEX_GSS_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
{ KEX_GSS_NISTP256_SHA256_ID, KEX_GSS_NISTP256_SHA256,
NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
{ KEX_GSS_C25519_SHA256_ID, KEX_GSS_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
#endif
{ NULL, 0, -1, -1},
};
char *
kex_alg_list(char sep)
static char *
kex_alg_list_internal(char sep, const struct kexalg *algs)
{
char *ret = NULL, *tmp;
size_t nlen, rlen = 0;
const struct kexalg *k;
for (k = kexalgs; k->name != NULL; k++) {
for (k = algs; k->name != NULL; k++) {
if (ret != NULL)
ret[rlen++] = sep;
nlen = strlen(k->name);
@ -138,6 +156,18 @@ kex_alg_list(char sep)
return ret;
}
char *
kex_alg_list(char sep)
{
return kex_alg_list_internal(sep, kexalgs);
}
char *
kex_gss_alg_list(char sep)
{
return kex_alg_list_internal(sep, gss_kexalgs);
}
static const struct kexalg *
kex_alg_by_name(const char *name)
{
@ -147,6 +177,10 @@ kex_alg_by_name(const char *name)
if (strcmp(k->name, name) == 0)
return k;
}
for (k = gss_kexalgs; k->name != NULL; k++) {
if (strncmp(k->name, name, strlen(k->name)) == 0)
return k;
}
return NULL;
}
@ -315,6 +349,29 @@ kex_assemble_names(char **listp, const char *def, const char *all)
return r;
}
/* Validate GSS KEX method name list */
int
kex_gss_names_valid(const char *names)
{
char *s, *cp, *p;
if (names == NULL || *names == '\0')
return 0;
s = cp = xstrdup(names);
for ((p = strsep(&cp, ",")); p && *p != '\0';
(p = strsep(&cp, ","))) {
if (strncmp(p, "gss-", 4) != 0
|| kex_alg_by_name(p) == NULL) {
error("Unsupported KEX algorithm \"%.100s\"", p);
free(s);
return 0;
}
}
debug3("gss kex names ok: [%s]", names);
free(s);
return 1;
}
/* put algorithm proposal into buffer */
int
kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
@ -698,6 +755,9 @@ kex_free(struct kex *kex)
sshbuf_free(kex->server_version);
sshbuf_free(kex->client_pub);
free(kex->session_id);
#ifdef GSSAPI
free(kex->gss_host);
#endif /* GSSAPI */
free(kex->failed_choice);
free(kex->hostkey_alg);
free(kex->name);

29
kex.h
View File

@ -102,6 +102,15 @@ enum kex_exchange {
KEX_ECDH_SHA2,
KEX_C25519_SHA256,
KEX_KEM_SNTRUP4591761X25519_SHA512,
#ifdef GSSAPI
KEX_GSS_GRP1_SHA1,
KEX_GSS_GRP14_SHA1,
KEX_GSS_GRP14_SHA256,
KEX_GSS_GRP16_SHA512,
KEX_GSS_GEX_SHA1,
KEX_GSS_NISTP256_SHA256,
KEX_GSS_C25519_SHA256,
#endif
KEX_MAX
};
@ -153,6 +162,12 @@ struct kex {
u_int flags;
int hash_alg;
int ec_nid;
#ifdef GSSAPI
int gss_deleg_creds;
int gss_trust_dns;
char *gss_host;
char *gss_client;
#endif
char *failed_choice;
int (*verify_host_key)(struct sshkey *, struct ssh *);
struct sshkey *(*load_host_public_key)(int, int, struct ssh *);
@ -174,8 +189,10 @@ struct kex {
int kex_names_valid(const char *);
char *kex_alg_list(char);
char *kex_gss_alg_list(char);
char *kex_names_cat(const char *, const char *);
int kex_assemble_names(char **, const char *, const char *);
int kex_gss_names_valid(const char *);
int kex_exchange_identification(struct ssh *, int, const char *);
@ -202,6 +219,12 @@ int kexgex_client(struct ssh *);
int kexgex_server(struct ssh *);
int kex_gen_client(struct ssh *);
int kex_gen_server(struct ssh *);
#if defined(GSSAPI) && defined(WITH_OPENSSL)
int kexgssgex_client(struct ssh *);
int kexgssgex_server(struct ssh *);
int kexgss_client(struct ssh *);
int kexgss_server(struct ssh *);
#endif
int kex_dh_keypair(struct kex *);
int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **,
@ -234,6 +257,12 @@ int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *,
const BIGNUM *, const u_char *, size_t,
u_char *, size_t *);
int kex_gen_hash(int hash_alg, const struct sshbuf *client_version,
const struct sshbuf *server_version, const struct sshbuf *client_kexinit,
const struct sshbuf *server_kexinit, const struct sshbuf *server_host_key_blob,
const struct sshbuf *client_pub, const struct sshbuf *server_pub,
const struct sshbuf *shared_secret, u_char *hash, size_t *hashlen);
void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
__attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
__attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)));

10
kexdh.c
View File

@ -48,13 +48,23 @@ kex_dh_keygen(struct kex *kex)
{
switch (kex->kex_type) {
case KEX_DH_GRP1_SHA1:
#ifdef GSSAPI
case KEX_GSS_GRP1_SHA1:
#endif
kex->dh = dh_new_group1();
break;
case KEX_DH_GRP14_SHA1:
case KEX_DH_GRP14_SHA256:
#ifdef GSSAPI
case KEX_GSS_GRP14_SHA1:
case KEX_GSS_GRP14_SHA256:
#endif
kex->dh = dh_new_group14();
break;
case KEX_DH_GRP16_SHA512:
#ifdef GSSAPI
case KEX_GSS_GRP16_SHA512:
#endif
kex->dh = dh_new_group16();
break;
case KEX_DH_GRP18_SHA512:

2
kexgen.c
View File

@ -44,7 +44,7 @@
static int input_kex_gen_init(int, u_int32_t, struct ssh *);
static int input_kex_gen_reply(int type, u_int32_t seq, struct ssh *ssh);
static int
int
kex_gen_hash(
int hash_alg,
const struct sshbuf *client_version,

606
kexgssc.c Normal file
View File

@ -0,0 +1,606 @@
/*
* Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#if defined(GSSAPI) && defined(WITH_OPENSSL)
#include "includes.h"
#include <openssl/crypto.h>
#include <openssl/bn.h>
#include <string.h>
#include "xmalloc.h"
#include "sshbuf.h"
#include "ssh2.h"
#include "sshkey.h"
#include "cipher.h"
#include "kex.h"
#include "log.h"
#include "packet.h"
#include "dh.h"
#include "digest.h"
#include "ssherr.h"
#include "ssh-gss.h"
int
kexgss_client(struct ssh *ssh)
{
struct kex *kex = ssh->kex;
gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER,
recv_tok = GSS_C_EMPTY_BUFFER,
gssbuf, msg_tok = GSS_C_EMPTY_BUFFER, *token_ptr;
Gssctxt *ctxt;
OM_uint32 maj_status, min_status, ret_flags;
struct sshbuf *server_blob = NULL;
struct sshbuf *shared_secret = NULL;
struct sshbuf *server_host_key_blob = NULL;
struct sshbuf *empty = NULL;
u_char *msg;
int type = 0;
int first = 1;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t hashlen;
u_char c;
int r;
/* 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");
/* Step 1 */
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
case KEX_GSS_GRP14_SHA1:
case KEX_GSS_GRP14_SHA256:
case KEX_GSS_GRP16_SHA512:
r = kex_dh_keypair(kex);
break;
case KEX_GSS_NISTP256_SHA256:
r = kex_ecdh_keypair(kex);
break;
case KEX_GSS_C25519_SHA256:
r = kex_c25519_keypair(kex);
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
if (r != 0)
return r;
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)) {
/* XXX Useles code: Missing send? */
if (send_tok.length != 0) {
if ((r = sshpkt_start(ssh,
SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value,
send_tok.length)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
}
fatal("gss_init_context failed");
}
/* If we've got an old receive buffer get rid of it */
if (token_ptr != GSS_C_NO_BUFFER)
gss_release_buffer(&min_status, &recv_tok);
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) {
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_INIT)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value,
send_tok.length)) != 0 ||
(r = sshpkt_put_stringb(ssh, kex->client_pub)) != 0)
fatal("failed to construct packet: %s", ssh_err(r));
first = 0;
} else {
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value,
send_tok.length)) != 0)
fatal("failed to construct packet: %s", ssh_err(r));
}
if ((r = sshpkt_send(ssh)) != 0)
fatal("failed to send packet: %s", ssh_err(r));
gss_release_buffer(&min_status, &send_tok);
/* If we've sent them data, they should reply */
do {
type = ssh_packet_read(ssh);
if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
debug("Received KEXGSS_HOSTKEY");
if (server_host_key_blob)
fatal("Server host key received more than once");
if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
fatal("Failed to read server host key: %s", ssh_err(r));
}
} 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");
if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
&recv_tok)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("Failed to read token: %s", ssh_err(r));
break;
case SSH2_MSG_KEXGSS_COMPLETE:
debug("Received GSSAPI_COMPLETE");
if (msg_tok.value != NULL)
fatal("Received GSSAPI_COMPLETE twice?");
if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 ||
(r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
&msg_tok)) != 0)
fatal("Failed to read message: %s", ssh_err(r));
/* Is there a token included? */
if ((r = sshpkt_get_u8(ssh, &c)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
if (c) {
if ((r = ssh_gssapi_sshpkt_get_buffer_desc(
ssh, &recv_tok)) != 0)
fatal("Failed to read token: %s", ssh_err(r));
/* If we're already complete - protocol error */
if (maj_status == GSS_S_COMPLETE)
sshpkt_disconnect(ssh, "Protocol error: received token when complete");
} else {
/* No token included */
if (maj_status != GSS_S_COMPLETE)
sshpkt_disconnect(ssh, "Protocol error: did not receive final token");
}
if ((r = sshpkt_get_end(ssh)) != 0) {
fatal("Expecting end of packet.");
}
break;
case SSH2_MSG_KEXGSS_ERROR:
debug("Received Error");
if ((r = sshpkt_get_u32(ssh, &maj_status)) != 0 ||
(r = sshpkt_get_u32(ssh, &min_status)) != 0 ||
(r = sshpkt_get_string(ssh, &msg, NULL)) != 0 ||
(r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* lang tag */
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt_get failed: %s", ssh_err(r));
fatal("GSSAPI Error: \n%.400s", msg);
default:
sshpkt_disconnect(ssh, "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 server_blob and msg_tok
*/
if (type != SSH2_MSG_KEXGSS_COMPLETE)
fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
/* compute shared secret */
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
case KEX_GSS_GRP14_SHA1:
case KEX_GSS_GRP14_SHA256:
case KEX_GSS_GRP16_SHA512:
r = kex_dh_dec(kex, server_blob, &shared_secret);
break;
case KEX_GSS_C25519_SHA256:
if (sshbuf_ptr(server_blob)[sshbuf_len(server_blob)] & 0x80)
fatal("The received key has MSB of last octet set!");
r = kex_c25519_dec(kex, server_blob, &shared_secret);
break;
case KEX_GSS_NISTP256_SHA256:
if (sshbuf_len(server_blob) != 65)
fatal("The received NIST-P256 key did not match"
"expected length (expected 65, got %zu)", sshbuf_len(server_blob));
if (sshbuf_ptr(server_blob)[0] != POINT_CONVERSION_UNCOMPRESSED)
fatal("The received NIST-P256 key does not have first octet 0x04");
r = kex_ecdh_dec(kex, server_blob, &shared_secret);
break;
default:
r = SSH_ERR_INVALID_ARGUMENT;
break;
}
if (r != 0)
goto out;
if ((empty = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
hashlen = sizeof(hash);
if ((r = kex_gen_hash(
kex->hash_alg,
kex->client_version,
kex->server_version,
kex->my,
kex->peer,
(server_host_key_blob ? server_host_key_blob : empty),
kex->client_pub,
server_blob,
shared_secret,
hash, &hashlen)) != 0)
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)))
sshpkt_disconnect(ssh, "Hash's MIC didn't verify");
gss_release_buffer(&min_status, &msg_tok);
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);
if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
explicit_bzero(hash, sizeof(hash));
explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key));
sshbuf_free(empty);
sshbuf_free(server_host_key_blob);
sshbuf_free(server_blob);
sshbuf_free(shared_secret);
sshbuf_free(kex->client_pub);
kex->client_pub = NULL;
return r;
}
int
kexgssgex_client(struct ssh *ssh)
{
struct kex *kex = ssh->kex;
gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER,
recv_tok = GSS_C_EMPTY_BUFFER, gssbuf,
msg_tok = GSS_C_EMPTY_BUFFER, *token_ptr;
Gssctxt *ctxt;
OM_uint32 maj_status, min_status, ret_flags;
struct sshbuf *shared_secret = NULL;
BIGNUM *p = NULL;
BIGNUM *g = NULL;
struct sshbuf *buf = NULL;
struct sshbuf *server_host_key_blob = NULL;
struct sshbuf *server_blob = NULL;
BIGNUM *dh_server_pub = NULL;
u_char *msg;
int type = 0;
int first = 1;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t hashlen;
const BIGNUM *pub_key, *dh_p, *dh_g;
int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;
struct sshbuf *empty = NULL;
u_char c;
int r;
/* 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");
debug("Doing group exchange");
nbits = dh_estimate(kex->dh_need * 8);
kex->min = DH_GRP_MIN;
kex->max = DH_GRP_MAX;
kex->nbits = nbits;
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_GROUPREQ)) != 0 ||
(r = sshpkt_put_u32(ssh, min)) != 0 ||
(r = sshpkt_put_u32(ssh, nbits)) != 0 ||
(r = sshpkt_put_u32(ssh, max)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("Failed to construct a packet: %s", ssh_err(r));
if ((r = ssh_packet_read_expect(ssh, SSH2_MSG_KEXGSS_GROUP)) != 0)
fatal("Error: %s", ssh_err(r));
if ((r = sshpkt_get_bignum2(ssh, &p)) != 0 ||
(r = sshpkt_get_bignum2(ssh, &g)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("shpkt_get_bignum2 failed: %s", ssh_err(r));
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);
if ((kex->dh = dh_new_group(g, p)) == NULL)
fatal("dn_new_group() failed");
p = g = NULL; /* belong to kex->dh now */
if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
goto out;
DH_get0_key(kex->dh, &pub_key, NULL);
token_ptr = GSS_C_NO_BUFFER;
do {
/* Step 2 - call GSS_Init_sec_context() */
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)) {
/* XXX Useles code: Missing send? */
if (send_tok.length != 0) {
if ((r = sshpkt_start(ssh,
SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value,
send_tok.length)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
}
fatal("gss_init_context failed");
}
/* If we've got an old receive buffer get rid of it */
if (token_ptr != GSS_C_NO_BUFFER)
gss_release_buffer(&min_status, &recv_tok);
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) {
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_INIT)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value,
send_tok.length)) != 0 ||
(r = sshpkt_put_bignum2(ssh, pub_key)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
first = 0;
} else {
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
(r = sshpkt_put_string(ssh,send_tok.value,
send_tok.length)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
}
if ((r = sshpkt_send(ssh)) != 0)
fatal("sshpkt_send failed: %s", ssh_err(r));
gss_release_buffer(&min_status, &send_tok);
/* If we've sent them data, they should reply */
do {
type = ssh_packet_read(ssh);
if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
debug("Received KEXGSS_HOSTKEY");
if (server_host_key_blob)
fatal("Server host key received more than once");
if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
}
} 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");
if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
&recv_tok)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
break;
case SSH2_MSG_KEXGSS_COMPLETE:
debug("Received GSSAPI_COMPLETE");
if (msg_tok.value != NULL)
fatal("Received GSSAPI_COMPLETE twice?");
if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 ||
(r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
&msg_tok)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
/* Is there a token included? */
if ((r = sshpkt_get_u8(ssh, &c)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
if (c) {
if ((r = ssh_gssapi_sshpkt_get_buffer_desc(
ssh, &recv_tok)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
/* If we're already complete - protocol error */
if (maj_status == GSS_S_COMPLETE)
sshpkt_disconnect(ssh, "Protocol error: received token when complete");
} else {
/* No token included */
if (maj_status != GSS_S_COMPLETE)
sshpkt_disconnect(ssh, "Protocol error: did not receive final token");
}
break;
case SSH2_MSG_KEXGSS_ERROR:
debug("Received Error");
if ((r = sshpkt_get_u32(ssh, &maj_status)) != 0 ||
(r = sshpkt_get_u32(ssh, &min_status)) != 0 ||
(r = sshpkt_get_string(ssh, &msg, NULL)) != 0 ||
(r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* lang tag */
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
fatal("GSSAPI Error: \n%.400s", msg);
default:
sshpkt_disconnect(ssh, "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");
/* 7. C verifies that the key Q_S is valid */
/* 8. C computes shared secret */
if ((buf = sshbuf_new()) == NULL ||
(r = sshbuf_put_stringb(buf, server_blob)) != 0 ||
(r = sshbuf_get_bignum2(buf, &dh_server_pub)) != 0)
goto out;
sshbuf_free(buf);
buf = NULL;
if ((shared_secret = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = kex_dh_compute_key(kex, dh_server_pub, shared_secret)) != 0)
goto out;
if ((empty = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g);
hashlen = sizeof(hash);
if ((r = kexgex_hash(
kex->hash_alg,
kex->client_version,
kex->server_version,
kex->my,
kex->peer,
(server_host_key_blob ? server_host_key_blob : empty),
kex->min, kex->nbits, kex->max,
dh_p, dh_g,
pub_key,
dh_server_pub,
sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
hash, &hashlen)) != 0)
fatal("Failed to calculate hash: %s", ssh_err(r));
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)))
sshpkt_disconnect(ssh, "Hash's MIC didn't verify");
gss_release_buffer(&min_status, &msg_tok);
/* 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);
/* Finally derive the keys and send them */
if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
out:
sshbuf_free(buf);
sshbuf_free(server_blob);
sshbuf_free(empty);
explicit_bzero(hash, sizeof(hash));
DH_free(kex->dh);
kex->dh = NULL;
BN_clear_free(dh_server_pub);
sshbuf_free(shared_secret);
sshbuf_free(server_host_key_blob);
return r;
}
#endif /* defined(GSSAPI) && defined(WITH_OPENSSL) */

474
kexgsss.c Normal file
View File

@ -0,0 +1,474 @@
/*
* Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#if defined(GSSAPI) && defined(WITH_OPENSSL)
#include <string.h>
#include <openssl/crypto.h>
#include <openssl/bn.h>
#include "xmalloc.h"
#include "sshbuf.h"
#include "ssh2.h"
#include "sshkey.h"
#include "cipher.h"
#include "kex.h"
#include "log.h"
#include "packet.h"
#include "dh.h"
#include "ssh-gss.h"
#include "monitor_wrap.h"
#include "misc.h" /* servconf.h needs misc.h for struct ForwardOptions */
#include "servconf.h"
#include "ssh-gss.h"
#include "digest.h"
#include "ssherr.h"
extern ServerOptions options;
int
kexgss_server(struct ssh *ssh)
{
struct kex *kex = ssh->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;
struct sshbuf *shared_secret = NULL;
struct sshbuf *client_pubkey = NULL;
struct sshbuf *server_pubkey = NULL;
struct sshbuf *empty = sshbuf_new();
int type = 0;
gss_OID oid;
char *mechs;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t hashlen;
int r;
/* 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()) {
mechs = ssh_gssapi_server_mechanisms();
free(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");
do {
debug("Wait SSH2_MSG_KEXGSS_INIT");
type = ssh_packet_read(ssh);
switch(type) {
case SSH2_MSG_KEXGSS_INIT:
if (client_pubkey != NULL)
fatal("Received KEXGSS_INIT after initialising");
if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
&recv_tok)) != 0 ||
(r = sshpkt_getb_froms(ssh, &client_pubkey)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
switch (kex->kex_type) {
case KEX_GSS_GRP1_SHA1:
case KEX_GSS_GRP14_SHA1:
case KEX_GSS_GRP14_SHA256:
case KEX_GSS_GRP16_SHA512:
r = kex_dh_enc(kex, client_pubkey, &server_pubkey,
&shared_secret);
break;
case KEX_GSS_NISTP256_SHA256:
r = kex_ecdh_enc(kex, client_pubkey, &server_pubkey,
&shared_secret);
break;
case KEX_GSS_C25519_SHA256:
r = kex_c25519_enc(kex, client_pubkey, &server_pubkey,
&shared_secret);
break;
default:
fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
}
if (r != 0)
goto out;
/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
break;
case SSH2_MSG_KEXGSS_CONTINUE:
if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
&recv_tok)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
break;
default:
sshpkt_disconnect(ssh,
"Protocol error: didn't expect packet type %d",
type);
}
maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok,
&send_tok, &ret_flags));
gss_release_buffer(&min_status, &recv_tok);
if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
fatal("Zero length token output when incomplete");
if (client_pubkey == NULL)
fatal("No client public key");
if (maj_status & GSS_S_CONTINUE_NEEDED) {
debug("Sending GSSAPI_CONTINUE");
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
gss_release_buffer(&min_status, &send_tok);
}
} while (maj_status & GSS_S_CONTINUE_NEEDED);
if (GSS_ERROR(maj_status)) {
if (send_tok.length > 0) {
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
}
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");
hashlen = sizeof(hash);
if ((r = kex_gen_hash(
kex->hash_alg,
kex->client_version,
kex->server_version,
kex->peer,
kex->my,
empty,
client_pubkey,
server_pubkey,
shared_secret,
hash, &hashlen)) != 0)
goto out;
gssbuf.value = hash;
gssbuf.length = hashlen;
if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok))))
fatal("Couldn't get MIC");
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_COMPLETE)) != 0 ||
(r = sshpkt_put_stringb(ssh, server_pubkey)) != 0 ||
(r = sshpkt_put_string(ssh, msg_tok.value, msg_tok.length)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
if (send_tok.length != 0) {
if ((r = sshpkt_put_u8(ssh, 1)) != 0 || /* true */
(r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
} else {
if ((r = sshpkt_put_u8(ssh, 0)) != 0) /* false */
fatal("sshpkt failed: %s", ssh_err(r));
}
if ((r = sshpkt_send(ssh)) != 0)
fatal("sshpkt_send failed: %s", ssh_err(r));
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);
if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
/* If this was a rekey, then save out any delegated credentials we
* just exchanged. */
if (options.gss_store_rekey)
ssh_gssapi_rekey_creds();
out:
sshbuf_free(empty);
explicit_bzero(hash, sizeof(hash));
sshbuf_free(shared_secret);
sshbuf_free(client_pubkey);
sshbuf_free(server_pubkey);
return r;
}
int
kexgssgex_server(struct ssh *ssh)
{
struct kex *kex = ssh->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;
struct sshbuf *shared_secret = NULL;
int type = 0;
gss_OID oid;
char *mechs;
u_char hash[SSH_DIGEST_MAX_LENGTH];
size_t hashlen;
BIGNUM *dh_client_pub = NULL;
const BIGNUM *pub_key, *dh_p, *dh_g;
int min = -1, max = -1, nbits = -1;
int cmin = -1, cmax = -1; /* client proposal */
struct sshbuf *empty = sshbuf_new();
int r;
/* 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()))
free(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");
/* 5. S generates an ephemeral key pair (do the allocations early) */
debug("Doing group exchange");
ssh_packet_read_expect(ssh, SSH2_MSG_KEXGSS_GROUPREQ);
/* store client proposal to provide valid signature */
if ((r = sshpkt_get_u32(ssh, &cmin)) != 0 ||
(r = sshpkt_get_u32(ssh, &nbits)) != 0 ||
(r = sshpkt_get_u32(ssh, &cmax)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
kex->nbits = nbits;
kex->min = cmin;
kex->max = cmax;
min = MAX(DH_GRP_MIN, cmin);
max = MIN(DH_GRP_MAX, cmax);
nbits = MAXIMUM(DH_GRP_MIN, nbits);
nbits = MINIMUM(DH_GRP_MAX, nbits);
if (max < min || nbits < min || max < nbits)
fatal("GSS_GEX, bad parameters: %d !< %d !< %d",
min, nbits, max);
kex->dh = PRIVSEP(choose_dh(min, nbits, max));
if (kex->dh == NULL) {
sshpkt_disconnect(ssh, "Protocol error: no matching group found");
fatal("Protocol error: no matching group found");
}
DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g);
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_GROUP)) != 0 ||
(r = sshpkt_put_bignum2(ssh, dh_p)) != 0 ||
(r = sshpkt_put_bignum2(ssh, dh_g)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
if ((r = ssh_packet_write_wait(ssh)) != 0)
fatal("ssh_packet_write_wait: %s", ssh_err(r));
/* Compute our exchange value in parallel with the client */
if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
goto out;
do {
debug("Wait SSH2_MSG_GSSAPI_INIT");
type = ssh_packet_read(ssh);
switch(type) {
case SSH2_MSG_KEXGSS_INIT:
if (dh_client_pub != NULL)
fatal("Received KEXGSS_INIT after initialising");
if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
&recv_tok)) != 0 ||
(r = sshpkt_get_bignum2(ssh, &dh_client_pub)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
break;
case SSH2_MSG_KEXGSS_CONTINUE:
if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
&recv_tok)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
break;
default:
sshpkt_disconnect(ssh,
"Protocol error: didn't expect packet type %d",
type);
}
maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok,
&send_tok, &ret_flags));
gss_release_buffer(&min_status, &recv_tok);
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");
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
gss_release_buffer(&min_status, &send_tok);
}
} while (maj_status & GSS_S_CONTINUE_NEEDED);
if (GSS_ERROR(maj_status)) {
if (send_tok.length > 0) {
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 ||
(r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
}
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");
/* calculate shared secret */
if ((shared_secret = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = kex_dh_compute_key(kex, dh_client_pub, shared_secret)) != 0)
goto out;
DH_get0_key(kex->dh, &pub_key, NULL);
DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g);
hashlen = sizeof(hash);
if ((r = kexgex_hash(
kex->hash_alg,
kex->client_version,
kex->server_version,
kex->peer,
kex->my,
empty,
cmin, nbits, cmax,
dh_p, dh_g,
dh_client_pub,
pub_key,
sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
hash, &hashlen)) != 0)
fatal("kexgex_hash failed: %s", ssh_err(r));
gssbuf.value = hash;
gssbuf.length = hashlen;
if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok))))
fatal("Couldn't get MIC");
if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_COMPLETE)) != 0 ||
(r = sshpkt_put_bignum2(ssh, pub_key)) != 0 ||
(r = sshpkt_put_string(ssh, msg_tok.value, msg_tok.length)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
if (send_tok.length != 0) {
if ((r = sshpkt_put_u8(ssh, 1)) != 0 || /* true */
(r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
} else {
if ((r = sshpkt_put_u8(ssh, 0)) != 0) /* false */
fatal("sshpkt failed: %s", ssh_err(r));
}
if ((r = sshpkt_send(ssh)) != 0)
fatal("sshpkt failed: %s", ssh_err(r));
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);
/* Finally derive the keys and send them */
if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
r = kex_send_newkeys(ssh);
/* If this was a rekey, then save out any delegated credentials we
* just exchanged. */
if (options.gss_store_rekey)
ssh_gssapi_rekey_creds();
out:
sshbuf_free(empty);
explicit_bzero(hash, sizeof(hash));
DH_free(kex->dh);
kex->dh = NULL;
BN_clear_free(dh_client_pub);
sshbuf_free(shared_secret);
return r;
}
#endif /* defined(GSSAPI) && defined(WITH_OPENSSL) */

139
monitor.c
View File

@ -148,6 +148,8 @@ int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *);
int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *);
int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *);
int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *);
int mm_answer_gss_sign(struct ssh *, int, struct sshbuf *);
int mm_answer_gss_updatecreds(struct ssh *, int, struct sshbuf *);
#endif
#ifdef SSH_AUDIT_EVENTS
@ -220,11 +222,18 @@ struct mon_table mon_dispatch_proto20[] = {
{MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx},
{MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok},
{MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic},
{MONITOR_REQ_GSSSIGN, MON_ONCE, mm_answer_gss_sign},
#endif
{0, 0, NULL}
};
struct mon_table mon_dispatch_postauth20[] = {
#ifdef GSSAPI
{MONITOR_REQ_GSSSETUP, 0, mm_answer_gss_setup_ctx},
{MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx},
{MONITOR_REQ_GSSSIGN, 0, mm_answer_gss_sign},
{MONITOR_REQ_GSSUPCREDS, 0, mm_answer_gss_updatecreds},
#endif
#ifdef WITH_OPENSSL
{MONITOR_REQ_MODULI, 0, mm_answer_moduli},
#endif
@ -293,6 +302,10 @@ monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
/* Permit requests for moduli and signatures */
monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
#ifdef GSSAPI
/* and for the GSSAPI key exchange */
monitor_permit(mon_dispatch, MONITOR_REQ_GSSSETUP, 1);
#endif
/* The first few requests do not require asynchronous access */
while (!authenticated) {
@ -406,6 +419,10 @@ monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
#ifdef GSSAPI
/* and for the GSSAPI key exchange */
monitor_permit(mon_dispatch, MONITOR_REQ_GSSSETUP, 1);
#endif
if (auth_opts->permit_pty_flag) {
monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
@ -1713,6 +1730,17 @@ monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor)
# ifdef OPENSSL_HAS_ECC
kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
# endif
# ifdef GSSAPI
if (options.gss_keyex) {
kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server;
kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server;
kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server;
kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server;
kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server;
}
# endif
#endif /* WITH_OPENSSL */
kex->kex[KEX_C25519_SHA256] = kex_gen_server;
kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server;
@ -1806,8 +1834,8 @@ mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
u_char *p;
int r;
if (!options.gss_authentication)
fatal("%s: GSSAPI authentication not enabled", __func__);
if (!options.gss_authentication && !options.gss_keyex)
fatal("%s: GSSAPI not enabled", __func__);
if ((r = sshbuf_get_string(m, &p, &len)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
@ -1839,8 +1867,8 @@ mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
OM_uint32 flags = 0; /* GSI needs this */
int r;
if (!options.gss_authentication)
fatal("%s: GSSAPI authentication not enabled", __func__);
if (!options.gss_authentication && !options.gss_keyex)
fatal("%s: GSSAPI not enabled", __func__);
if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
@ -1860,6 +1888,7 @@ mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_GSSSIGN, 1);
}
return (0);
}
@ -1871,8 +1900,8 @@ mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
OM_uint32 ret;
int r;
if (!options.gss_authentication)
fatal("%s: GSSAPI authentication not enabled", __func__);
if (!options.gss_authentication && !options.gss_keyex)
fatal("%s: GSSAPI not enabled", __func__);
if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
(r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
@ -1898,13 +1927,17 @@ mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
int
mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
{
int r, authenticated;
int r, authenticated, kex;
const char *displayname;
if (!options.gss_authentication)
fatal("%s: GSSAPI authentication not enabled", __func__);
if (!options.gss_authentication && !options.gss_keyex)
fatal("%s: GSSAPI not enabled", __func__);
authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
if ((r = sshbuf_get_u32(m, &kex)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
authenticated = authctxt->valid &&
ssh_gssapi_userok(authctxt->user, authctxt->pw, kex);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, authenticated)) != 0)
@ -1913,7 +1946,11 @@ mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
debug3("%s: sending result %d", __func__, authenticated);
mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
auth_method = "gssapi-with-mic";
if (kex) {
auth_method = "gssapi-keyex";
} else {
auth_method = "gssapi-with-mic";
}
if ((displayname = ssh_gssapi_displayname()) != NULL)
auth2_record_info(authctxt, "%s", displayname);
@ -1921,5 +1958,85 @@ mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
/* Monitor loop will terminate if authenticated */
return (authenticated);
}
int
mm_answer_gss_sign(struct ssh *ssh, int socket, struct sshbuf *m)
{
gss_buffer_desc data;
gss_buffer_desc hash = GSS_C_EMPTY_BUFFER;
OM_uint32 major, minor;
size_t len;
u_char *p = NULL;
int r;
if (!options.gss_authentication && !options.gss_keyex)
fatal("%s: GSSAPI not enabled", __func__);
if ((r = sshbuf_get_string(m, &p, &len)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
data.value = p;
data.length = len;
/* Lengths of SHA-1, SHA-256 and SHA-512 hashes that are used */
if (data.length != 20 && data.length != 32 && data.length != 64)
fatal("%s: data length incorrect: %d", __func__,
(int) data.length);
/* Save the session ID on the first time around */
if (session_id2_len == 0) {
session_id2_len = data.length;
session_id2 = xmalloc(session_id2_len);
memcpy(session_id2, data.value, session_id2_len);
}
major = ssh_gssapi_sign(gsscontext, &data, &hash);
free(data.value);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, major)) != 0 ||
(r = sshbuf_put_string(m, hash.value, hash.length)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(socket, MONITOR_ANS_GSSSIGN, m);
gss_release_buffer(&minor, &hash);
/* Turn on getpwnam permissions */
monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
/* And credential updating, for when rekeying */
monitor_permit(mon_dispatch, MONITOR_REQ_GSSUPCREDS, 1);
return (0);
}
int
mm_answer_gss_updatecreds(struct ssh *ssh, int socket, struct sshbuf *m) {
ssh_gssapi_ccache store;
int r, ok;
if (!options.gss_authentication && !options.gss_keyex)
fatal("%s: GSSAPI not enabled", __func__);
if ((r = sshbuf_get_string(m, (u_char **)&store.filename, NULL)) != 0 ||
(r = sshbuf_get_string(m, (u_char **)&store.envvar, NULL)) != 0 ||
(r = sshbuf_get_string(m, (u_char **)&store.envval, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
ok = ssh_gssapi_update_creds(&store);
free(store.filename);
free(store.envvar);
free(store.envval);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, ok)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(socket, MONITOR_ANS_GSSUPCREDS, m);
return(0);
}
#endif /* GSSAPI */

2
monitor.h
View File

@ -63,6 +63,8 @@ enum monitor_reqtype {
MONITOR_REQ_PAM_FREE_CTX = 110, MONITOR_ANS_PAM_FREE_CTX = 111,
MONITOR_REQ_AUDIT_EVENT = 112, MONITOR_REQ_AUDIT_COMMAND = 113,
MONITOR_REQ_GSSSIGN = 150, MONITOR_ANS_GSSSIGN = 151,
MONITOR_REQ_GSSUPCREDS = 152, MONITOR_ANS_GSSUPCREDS = 153,
};
struct ssh;

57
monitor_wrap.c
View File

@ -993,13 +993,15 @@ mm_ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
}
int
mm_ssh_gssapi_userok(char *user)
mm_ssh_gssapi_userok(char *user, struct passwd *pw, int kex)
{
struct sshbuf *m;
int r, authenticated = 0;
if ((m = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_u32(m, kex)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUSEROK, m);
mm_request_receive_expect(pmonitor->m_recvfd,
@ -1012,4 +1014,57 @@ mm_ssh_gssapi_userok(char *user)
debug3("%s: user %sauthenticated",__func__, authenticated ? "" : "not ");
return (authenticated);
}
OM_uint32
mm_ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_desc *data, gss_buffer_desc *hash)
{
struct sshbuf *m;
OM_uint32 major;
int r;
if ((m = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_string(m, data->value, data->length)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSIGN, m);
mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSIGN, m);
if ((r = sshbuf_get_u32(m, &major)) != 0 ||
(r = ssh_gssapi_get_buffer_desc(m, hash)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sshbuf_free(m);
return (major);
}
int
mm_ssh_gssapi_update_creds(ssh_gssapi_ccache *store)
{
struct sshbuf *m;
int r, ok;
if ((m = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_cstring(m,
store->filename ? store->filename : "")) != 0 ||
(r = sshbuf_put_cstring(m,
store->envvar ? store->envvar : "")) != 0 ||
(r = sshbuf_put_cstring(m,
store->envval ? store->envval : "")) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUPCREDS, m);
mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSUPCREDS, m);
if ((r = sshbuf_get_u32(m, &ok)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
sshbuf_free(m);
return (ok);
}
#endif /* GSSAPI */

4
monitor_wrap.h
View File

@ -64,8 +64,10 @@ int mm_sshkey_verify(const struct sshkey *, const u_char *, size_t,
OM_uint32 mm_ssh_gssapi_server_ctx(Gssctxt **, gss_OID);
OM_uint32 mm_ssh_gssapi_accept_ctx(Gssctxt *,
gss_buffer_desc *, gss_buffer_desc *, OM_uint32 *);
int mm_ssh_gssapi_userok(char *user);
int mm_ssh_gssapi_userok(char *user, struct passwd *, int kex);
OM_uint32 mm_ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t);
OM_uint32 mm_ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t);
int mm_ssh_gssapi_update_creds(ssh_gssapi_ccache *);
#endif
#ifdef USE_PAM

70
readconf.c
View File

@ -67,6 +67,7 @@
#include "uidswap.h"
#include "myproposal.h"
#include "digest.h"
#include "ssh-gss.h"
/* Format of the configuration file:
@ -160,6 +161,8 @@ typedef enum {
oClearAllForwardings, oNoHostAuthenticationForLocalhost,
oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout,
oAddressFamily, oGssAuthentication, oGssDelegateCreds,
oGssTrustDns, oGssKeyEx, oGssClientIdentity, oGssRenewalRekey,
oGssServerIdentity, oGssKexAlgorithms,
oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly,
oSendEnv, oSetEnv, oControlPath, oControlMaster, oControlPersist,
oHashKnownHosts,
@ -204,10 +207,22 @@ static struct {
/* Sometimes-unsupported options */
#if defined(GSSAPI)
{ "gssapiauthentication", oGssAuthentication },
{ "gssapikeyexchange", oGssKeyEx },
{ "gssapidelegatecredentials", oGssDelegateCreds },
{ "gssapitrustdns", oGssTrustDns },
{ "gssapiclientidentity", oGssClientIdentity },
{ "gssapiserveridentity", oGssServerIdentity },
{ "gssapirenewalforcesrekey", oGssRenewalRekey },
{ "gssapikexalgorithms", oGssKexAlgorithms },
# else
{ "gssapiauthentication", oUnsupported },
{ "gssapikeyexchange", oUnsupported },
{ "gssapidelegatecredentials", oUnsupported },
{ "gssapitrustdns", oUnsupported },
{ "gssapiclientidentity", oUnsupported },
{ "gssapiserveridentity", oUnsupported },
{ "gssapirenewalforcesrekey", oUnsupported },
{ "gssapikexalgorithms", oUnsupported },
#endif
#ifdef ENABLE_PKCS11
{ "pkcs11provider", oPKCS11Provider },
@ -1029,10 +1044,42 @@ parse_time:
intptr = &options->gss_authentication;
goto parse_flag;
case oGssKeyEx:
intptr = &options->gss_keyex;
goto parse_flag;
case oGssDelegateCreds:
intptr = &options->gss_deleg_creds;
goto parse_flag;
case oGssTrustDns:
intptr = &options->gss_trust_dns;
goto parse_flag;
case oGssClientIdentity:
charptr = &options->gss_client_identity;
goto parse_string;
case oGssServerIdentity:
charptr = &options->gss_server_identity;
goto parse_string;
case oGssRenewalRekey:
intptr = &options->gss_renewal_rekey;
goto parse_flag;
case oGssKexAlgorithms:
arg = strdelim(&s);
if (!arg || *arg == '\0')
fatal("%.200s line %d: Missing argument.",
filename, linenum);
if (!kex_gss_names_valid(arg))
fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.",
filename, linenum, arg ? arg : "<NONE>");
if (*activep && options->gss_kex_algorithms == NULL)
options->gss_kex_algorithms = xstrdup(arg);
break;
case oBatchMode:
intptr = &options->batch_mode;
goto parse_flag;
@ -1911,7 +1958,13 @@ initialize_options(Options * options)
options->pubkey_authentication = -1;
options->challenge_response_authentication = -1;
options->gss_authentication = -1;
options->gss_keyex = -1;
options->gss_deleg_creds = -1;
options->gss_trust_dns = -1;
options->gss_renewal_rekey = -1;
options->gss_client_identity = NULL;
options->gss_server_identity = NULL;
options->gss_kex_algorithms = NULL;
options->password_authentication = -1;
options->kbd_interactive_authentication = -1;
options->kbd_interactive_devices = NULL;
@ -2059,8 +2112,18 @@ fill_default_options(Options * options)
options->challenge_response_authentication = 1;
if (options->gss_authentication == -1)
options->gss_authentication = 0;
if (options->gss_keyex == -1)
options->gss_keyex = 0;
if (options->gss_deleg_creds == -1)
options->gss_deleg_creds = 0;
if (options->gss_trust_dns == -1)
options->gss_trust_dns = 0;
if (options->gss_renewal_rekey == -1)
options->gss_renewal_rekey = 0;
#ifdef GSSAPI
if (options->gss_kex_algorithms == NULL)
options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX);
#endif
if (options->password_authentication == -1)
options->password_authentication = 1;
if (options->kbd_interactive_authentication == -1)
@ -2702,7 +2765,14 @@ dump_client_config(Options *o, const char *host)
dump_cfg_fmtint(oGatewayPorts, o->fwd_opts.gateway_ports);
#ifdef GSSAPI
dump_cfg_fmtint(oGssAuthentication, o->gss_authentication);
dump_cfg_fmtint(oGssKeyEx, o->gss_keyex);
dump_cfg_fmtint(oGssDelegateCreds, o->gss_deleg_creds);
dump_cfg_fmtint(oGssTrustDns, o->gss_trust_dns);
dump_cfg_fmtint(oGssRenewalRekey, o->gss_renewal_rekey);
dump_cfg_string(oGssClientIdentity, o->gss_client_identity);
dump_cfg_string(oGssServerIdentity, o->gss_server_identity);
dump_cfg_string(oGssKexAlgorithms, o->gss_kex_algorithms ?
o->gss_kex_algorithms : GSS_KEX_DEFAULT_KEX);
#endif /* GSSAPI */
dump_cfg_fmtint(oHashKnownHosts, o->hash_known_hosts);
dump_cfg_fmtint(oHostbasedAuthentication, o->hostbased_authentication);

6
readconf.h
View File

@ -41,7 +41,13 @@ typedef struct {
int challenge_response_authentication;
/* Try S/Key or TIS, authentication. */
int gss_authentication; /* Try GSS authentication */
int gss_keyex; /* Try GSS key exchange */
int gss_deleg_creds; /* Delegate GSS credentials */
int gss_trust_dns; /* Trust DNS for GSS canonicalization */
int gss_renewal_rekey; /* Credential renewal forces rekey */
char *gss_client_identity; /* Principal to initiate GSSAPI with */
char *gss_server_identity; /* GSSAPI target principal */
char *gss_kex_algorithms; /* GSSAPI kex methods to be offered by client. */
int password_authentication; /* Try password
* authentication. */
int kbd_interactive_authentication; /* Try keyboard-interactive auth. */

47
servconf.c
View File

@ -69,6 +69,7 @@
#include "auth.h"
#include "myproposal.h"
#include "digest.h"
#include "ssh-gss.h"
static void add_listen_addr(ServerOptions *, const char *,
const char *, int);
@ -133,8 +134,11 @@ initialize_server_options(ServerOptions *options)
options->kerberos_ticket_cleanup = -1;
options->kerberos_get_afs_token = -1;
options->gss_authentication=-1;
options->gss_keyex = -1;
options->gss_cleanup_creds = -1;
options->gss_strict_acceptor = -1;
options->gss_store_rekey = -1;
options->gss_kex_algorithms = NULL;
options->password_authentication = -1;
options->kbd_interactive_authentication = -1;
options->challenge_response_authentication = -1;
@ -375,10 +379,18 @@ fill_default_server_options(ServerOptions *options)
options->kerberos_get_afs_token = 0;
if (options->gss_authentication == -1)
options->gss_authentication = 0;
if (options->gss_keyex == -1)
options->gss_keyex = 0;
if (options->gss_cleanup_creds == -1)
options->gss_cleanup_creds = 1;
if (options->gss_strict_acceptor == -1)
options->gss_strict_acceptor = 1;
if (options->gss_store_rekey == -1)
options->gss_store_rekey = 0;
#ifdef GSSAPI
if (options->gss_kex_algorithms == NULL)
options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX);
#endif
if (options->password_authentication == -1)
options->password_authentication = 1;
if (options->kbd_interactive_authentication == -1)
@ -531,6 +543,7 @@ typedef enum {
sHostKeyAlgorithms,
sClientAliveInterval, sClientAliveCountMax, sAuthorizedKeysFile,
sGssAuthentication, sGssCleanupCreds, sGssStrictAcceptor,
sGssKeyEx, sGssKexAlgorithms, sGssStoreRekey,
sAcceptEnv, sSetEnv, sPermitTunnel,
sMatch, sPermitOpen, sPermitListen, sForceCommand, sChrootDirectory,
sUsePrivilegeSeparation, sAllowAgentForwarding,
@ -607,12 +620,22 @@ static struct {
#ifdef GSSAPI
{ "gssapiauthentication", sGssAuthentication, SSHCFG_ALL },
{ "gssapicleanupcredentials", sGssCleanupCreds, SSHCFG_GLOBAL },
{ "gssapicleanupcreds", sGssCleanupCreds, SSHCFG_GLOBAL },
{ "gssapistrictacceptorcheck", sGssStrictAcceptor, SSHCFG_GLOBAL },
{ "gssapikeyexchange", sGssKeyEx, SSHCFG_GLOBAL },
{ "gssapistorecredentialsonrekey", sGssStoreRekey, SSHCFG_GLOBAL },
{ "gssapikexalgorithms", sGssKexAlgorithms, SSHCFG_GLOBAL },
#else
{ "gssapiauthentication", sUnsupported, SSHCFG_ALL },
{ "gssapicleanupcredentials", sUnsupported, SSHCFG_GLOBAL },
{ "gssapicleanupcreds", sUnsupported, SSHCFG_GLOBAL },
{ "gssapistrictacceptorcheck", sUnsupported, SSHCFG_GLOBAL },
{ "gssapikeyexchange", sUnsupported, SSHCFG_GLOBAL },
{ "gssapistorecredentialsonrekey", sUnsupported, SSHCFG_GLOBAL },
{ "gssapikexalgorithms", sUnsupported, SSHCFG_GLOBAL },
#endif
{ "gssusesessionccache", sUnsupported, SSHCFG_GLOBAL },
{ "gssapiusesessioncredcache", sUnsupported, SSHCFG_GLOBAL },
{ "passwordauthentication", sPasswordAuthentication, SSHCFG_ALL },
{ "kbdinteractiveauthentication", sKbdInteractiveAuthentication, SSHCFG_ALL },
{ "challengeresponseauthentication", sChallengeResponseAuthentication, SSHCFG_GLOBAL },
@ -1548,6 +1571,10 @@ process_server_config_line_depth(ServerOptions *options, char *line,
intptr = &options->gss_authentication;
goto parse_flag;
case sGssKeyEx:
intptr = &options->gss_keyex;
goto parse_flag;
case sGssCleanupCreds:
intptr = &options->gss_cleanup_creds;
goto parse_flag;
@ -1556,6 +1583,22 @@ process_server_config_line_depth(ServerOptions *options, char *line,
intptr = &options->gss_strict_acceptor;
goto parse_flag;
case sGssStoreRekey:
intptr = &options->gss_store_rekey;
goto parse_flag;
case sGssKexAlgorithms:
arg = strdelim(&cp);
if (!arg || *arg == '\0')
fatal("%.200s line %d: Missing argument.",
filename, linenum);
if (!kex_gss_names_valid(arg))
fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.",
filename, linenum, arg ? arg : "<NONE>");
if (*activep && options->gss_kex_algorithms == NULL)
options->gss_kex_algorithms = xstrdup(arg);
break;
case sPasswordAuthentication:
intptr = &options->password_authentication;
goto parse_flag;
@ -2777,6 +2820,10 @@ dump_config(ServerOptions *o)
#ifdef GSSAPI
dump_cfg_fmtint(sGssAuthentication, o->gss_authentication);
dump_cfg_fmtint(sGssCleanupCreds, o->gss_cleanup_creds);
dump_cfg_fmtint(sGssKeyEx, o->gss_keyex);
dump_cfg_fmtint(sGssStrictAcceptor, o->gss_strict_acceptor);
dump_cfg_fmtint(sGssStoreRekey, o->gss_store_rekey);
dump_cfg_string(sGssKexAlgorithms, o->gss_kex_algorithms);
#endif
dump_cfg_fmtint(sPasswordAuthentication, o->password_authentication);
dump_cfg_fmtint(sKbdInteractiveAuthentication,

3
servconf.h
View File

@ -132,8 +132,11 @@ typedef struct {
int kerberos_get_afs_token; /* If true, try to get AFS token if
* authenticated with Kerberos. */
int gss_authentication; /* If true, permit GSSAPI authentication */
int gss_keyex; /* If true, permit GSSAPI key exchange */
int gss_cleanup_creds; /* If true, destroy cred cache on logout */
int gss_strict_acceptor; /* If true, restrict the GSSAPI acceptor name */
int gss_store_rekey;
char *gss_kex_algorithms; /* GSSAPI kex methods to be offered by client. */
int password_authentication; /* If true, permit password
* authentication. */
int kbd_interactive_authentication; /* If true, permit */

10
session.c
View File

@ -2678,13 +2678,19 @@ do_cleanup(struct ssh *ssh, Authctxt *authctxt)
#ifdef KRB5
if (options.kerberos_ticket_cleanup &&
authctxt->krb5_ctx)
authctxt->krb5_ctx) {
temporarily_use_uid(authctxt->pw);
krb5_cleanup_proc(authctxt);
restore_uid();
}
#endif
#ifdef GSSAPI
if (options.gss_cleanup_creds)
if (options.gss_cleanup_creds) {
temporarily_use_uid(authctxt->pw);
ssh_gssapi_cleanup_creds();
restore_uid();
}
#endif
/* remove agent socket */

50
ssh-gss.h
View File

@ -1,6 +1,6 @@
/* $OpenBSD: ssh-gss.h,v 1.14 2018/07/10 09:13:30 djm Exp $ */
/*
* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
* Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -61,10 +61,30 @@
#define SSH_GSS_OIDTYPE 0x06
#define SSH2_MSG_KEXGSS_INIT 30
#define SSH2_MSG_KEXGSS_CONTINUE 31
#define SSH2_MSG_KEXGSS_COMPLETE 32
#define SSH2_MSG_KEXGSS_HOSTKEY 33
#define SSH2_MSG_KEXGSS_ERROR 34
#define SSH2_MSG_KEXGSS_GROUPREQ 40
#define SSH2_MSG_KEXGSS_GROUP 41
#define KEX_GSS_GRP1_SHA1_ID "gss-group1-sha1-"
#define KEX_GSS_GRP14_SHA1_ID "gss-group14-sha1-"
#define KEX_GSS_GRP14_SHA256_ID "gss-group14-sha256-"
#define KEX_GSS_GRP16_SHA512_ID "gss-group16-sha512-"
#define KEX_GSS_GEX_SHA1_ID "gss-gex-sha1-"
#define KEX_GSS_NISTP256_SHA256_ID "gss-nistp256-sha256-"
#define KEX_GSS_C25519_SHA256_ID "gss-curve25519-sha256-"
#define GSS_KEX_DEFAULT_KEX \
KEX_GSS_GEX_SHA1_ID "," \
KEX_GSS_GRP14_SHA1_ID
typedef struct {
char *filename;
char *envvar;
char *envval;
struct passwd *owner;
void *data;
} ssh_gssapi_ccache;
@ -72,8 +92,11 @@ typedef struct {
gss_buffer_desc displayname;
gss_buffer_desc exportedname;
gss_cred_id_t creds;
gss_name_t name;
struct ssh_gssapi_mech_struct *mech;
ssh_gssapi_ccache store;
int used;
int updated;
} ssh_gssapi_client;
typedef struct ssh_gssapi_mech_struct {
@ -84,6 +107,7 @@ typedef struct ssh_gssapi_mech_struct {
int (*userok) (ssh_gssapi_client *, char *);
int (*localname) (ssh_gssapi_client *, char **);
void (*storecreds) (ssh_gssapi_client *);
int (*updatecreds) (ssh_gssapi_ccache *, ssh_gssapi_client *);
} ssh_gssapi_mech;
typedef struct {
@ -94,10 +118,11 @@ typedef struct {
gss_OID oid; /* client */
gss_cred_id_t creds; /* server */
gss_name_t client; /* server */
gss_cred_id_t client_creds; /* server */
gss_cred_id_t client_creds; /* both */
} Gssctxt;
extern ssh_gssapi_mech *supported_mechs[];
extern Gssctxt *gss_kex_context;
int ssh_gssapi_check_oid(Gssctxt *, void *, size_t);
void ssh_gssapi_set_oid_data(Gssctxt *, void *, size_t);
@ -109,6 +134,7 @@ OM_uint32 ssh_gssapi_test_oid_supported(OM_uint32 *, gss_OID, int *);
struct sshbuf;
int ssh_gssapi_get_buffer_desc(struct sshbuf *, gss_buffer_desc *);
int ssh_gssapi_sshpkt_get_buffer_desc(struct ssh *, gss_buffer_desc *);
OM_uint32 ssh_gssapi_import_name(Gssctxt *, const char *);
OM_uint32 ssh_gssapi_init_ctx(Gssctxt *, int,
@ -123,17 +149,33 @@ void ssh_gssapi_delete_ctx(Gssctxt **);
OM_uint32 ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t);
void ssh_gssapi_buildmic(struct sshbuf *, const char *,
const char *, const char *);
int ssh_gssapi_check_mechanism(Gssctxt **, gss_OID, const char *);
int ssh_gssapi_check_mechanism(Gssctxt **, gss_OID, const char *, const char *);
OM_uint32 ssh_gssapi_client_identity(Gssctxt *, const char *);
int ssh_gssapi_credentials_updated(Gssctxt *);
/* In the server */
typedef int ssh_gssapi_check_fn(Gssctxt **, gss_OID, const char *,
const char *);
char *ssh_gssapi_client_mechanisms(const char *, const char *, const char *);
char *ssh_gssapi_kex_mechs(gss_OID_set, ssh_gssapi_check_fn *, const char *,
const char *, const char *);
gss_OID ssh_gssapi_id_kex(Gssctxt *, char *, int);
int ssh_gssapi_server_check_mech(Gssctxt **,gss_OID, const char *,
const char *);
OM_uint32 ssh_gssapi_server_ctx(Gssctxt **, gss_OID);
int ssh_gssapi_userok(char *name);
int ssh_gssapi_userok(char *name, struct passwd *, int kex);
OM_uint32 ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t);
void ssh_gssapi_do_child(char ***, u_int *);
void ssh_gssapi_cleanup_creds(void);
void ssh_gssapi_storecreds(void);
const char *ssh_gssapi_displayname(void);
char *ssh_gssapi_server_mechanisms(void);
int ssh_gssapi_oid_table_ok(void);
int ssh_gssapi_update_creds(ssh_gssapi_ccache *store);
void ssh_gssapi_rekey_creds(void);
#endif /* GSSAPI */
#endif /* _SSH_GSS_H */

8
ssh.1
View File

@ -503,7 +503,13 @@ For full details of the options listed below, and their possible values, see
.It GatewayPorts
.It GlobalKnownHostsFile
.It GSSAPIAuthentication
.It GSSAPIKeyExchange
.It GSSAPIClientIdentity
.It GSSAPIDelegateCredentials
.It GSSAPIKexAlgorithms
.It GSSAPIRenewalForcesRekey
.It GSSAPIServerIdentity
.It GSSAPITrustDns
.It HashKnownHosts
.It Host
.It HostbasedAuthentication
@ -579,6 +585,8 @@ flag),
(supported message integrity codes),
.Ar kex
(key exchange algorithms),
.Ar kex-gss
(GSSAPI key exchange algorithms),
.Ar key
(key types),
.Ar key-cert

6
ssh.c
View File

@ -747,6 +747,8 @@ main(int ac, char **av)
else if (strcmp(optarg, "kex") == 0 ||
strcasecmp(optarg, "KexAlgorithms") == 0)
cp = kex_alg_list('\n');
else if (strcmp(optarg, "kex-gss") == 0)
cp = kex_gss_alg_list('\n');
else if (strcmp(optarg, "key") == 0)
cp = sshkey_alg_list(0, 0, 0, '\n');
else if (strcmp(optarg, "key-cert") == 0)
@ -772,8 +774,8 @@ main(int ac, char **av)
} else if (strcmp(optarg, "help") == 0) {
cp = xstrdup(
"cipher\ncipher-auth\ncompression\nkex\n"
"key\nkey-cert\nkey-plain\nkey-sig\nmac\n"
"protocol-version\nsig");
"kex-gss\nkey\nkey-cert\nkey-plain\n"
"key-sig\nmac\nprotocol-version\nsig");
}
if (cp == NULL)
fatal("Unsupported query \"%s\"", optarg);

2
ssh_config
View File

@ -24,6 +24,8 @@
# HostbasedAuthentication no
# GSSAPIAuthentication no
# GSSAPIDelegateCredentials no
# GSSAPIKeyExchange no
# GSSAPITrustDNS no
# BatchMode no
# CheckHostIP yes
# AddressFamily any

57
ssh_config.5
View File

@ -766,10 +766,67 @@ The default is
Specifies whether user authentication based on GSSAPI is allowed.
The default is
.Cm no .
.It Cm GSSAPIClientIdentity
If set, specifies the GSSAPI client identity that ssh should use when
connecting to the server. The default is unset, which means that the default
identity will be used.
.It Cm GSSAPIDelegateCredentials
Forward (delegate) credentials to the server.
The default is
.Cm no .
.It Cm GSSAPIKeyExchange
Specifies whether key exchange based on GSSAPI may be used. When using
GSSAPI key exchange the server need not have a host key.
The default is
.Dq no .
.It Cm GSSAPIRenewalForcesRekey
If set to
.Dq yes
then renewal of the client's GSSAPI credentials will force the rekeying of the
ssh connection. With a compatible server, this will delegate the renewed
credentials to a session on the server.
.Pp
Checks are made to ensure that credentials are only propagated when the new
credentials match the old ones on the originating client and where the
receiving server still has the old set in its cache.
.Pp
The default is
.Dq no .
.Pp
For this to work
.Cm GSSAPIKeyExchange
needs to be enabled in the server and also used by the client.
.It Cm GSSAPIServerIdentity
If set, specifies the GSSAPI server identity that ssh should expect when
connecting to the server. The default is unset, which means that the
expected GSSAPI server identity will be determined from the target
hostname.
.It Cm GSSAPITrustDns
Set to
.Dq yes
to indicate that the DNS is trusted to securely canonicalize
the name of the host being connected to. If
.Dq no ,
the hostname entered on the
command line will be passed untouched to the GSSAPI library.
The default is
.Dq no .
.It Cm GSSAPIKexAlgorithms
The list of key exchange algorithms that are offered for GSSAPI
key exchange. Possible values are
.Bd -literal -offset 3n
gss-gex-sha1-,
gss-group1-sha1-,
gss-group14-sha1-,
gss-group14-sha256-,
gss-group16-sha512-,
gss-nistp256-sha256-,
gss-curve25519-sha256-
.Ed
.Pp
The default is
.Dq gss-gex-sha1-,gss-group14-sha1- .
This option only applies to protocol version 2 connections using GSSAPI.
.It Cm HashKnownHosts
Indicates that
.Xr ssh 1

142
sshconnect2.c
View File

@ -80,8 +80,6 @@
#endif
/* import */
extern char *client_version_string;
extern char *server_version_string;
extern Options options;
/*
@ -163,6 +161,11 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
char *s, *all_key;
int r, use_known_hosts_order = 0;
#if defined(GSSAPI) && defined(WITH_OPENSSL)
char *orig = NULL, *gss = NULL;
char *gss_host = NULL;
#endif
xxx_host = host;
xxx_hostaddr = hostaddr;
@ -206,6 +209,35 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
compat_pkalg_proposal(options.hostkeyalgorithms);
}
#if defined(GSSAPI) && defined(WITH_OPENSSL)
if (options.gss_keyex) {
/* Add the GSSAPI mechanisms currently supported on this
* client to the key exchange algorithm proposal */
orig = myproposal[PROPOSAL_KEX_ALGS];
if (options.gss_server_identity)
gss_host = xstrdup(options.gss_server_identity);
else if (options.gss_trust_dns)
gss_host = remote_hostname(ssh);
else
gss_host = xstrdup(host);
gss = ssh_gssapi_client_mechanisms(gss_host,
options.gss_client_identity, options.gss_kex_algorithms);
if (gss) {
debug("Offering GSSAPI proposal: %s", gss);
xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
"%s,%s", gss, orig);
/* If we've got GSSAPI algorithms, then we also support the
* 'null' hostkey, as a last resort */
orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
"%s,null", orig);
}
}
#endif
if (options.rekey_limit || options.rekey_interval)
ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
options.rekey_interval);
@ -224,16 +256,46 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
# ifdef OPENSSL_HAS_ECC
ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
# endif
#endif
# ifdef GSSAPI
if (options.gss_keyex) {
ssh->kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;
ssh->kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client;
ssh->kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_client;
ssh->kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_client;
ssh->kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_client;
ssh->kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_client;
ssh->kex->kex[KEX_GSS_C25519_SHA256] = kexgss_client;
}
# endif
#endif /* WITH_OPENSSL */
ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client;
ssh->kex->verify_host_key=&verify_host_key_callback;
#if defined(GSSAPI) && defined(WITH_OPENSSL)
if (options.gss_keyex) {
ssh->kex->gss_deleg_creds = options.gss_deleg_creds;
ssh->kex->gss_trust_dns = options.gss_trust_dns;
ssh->kex->gss_client = options.gss_client_identity;
ssh->kex->gss_host = gss_host;
}
#endif
ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done);
/* remove ext-info from the KEX proposals for rekeying */
myproposal[PROPOSAL_KEX_ALGS] =
compat_kex_proposal(options.kex_algorithms);
#if defined(GSSAPI) && defined(WITH_OPENSSL)
/* repair myproposal after it was crumpled by the */
/* ext-info removal above */
if (gss) {
orig = myproposal[PROPOSAL_KEX_ALGS];
xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
"%s,%s", gss, orig);
free(gss);
}
#endif
if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0)
fatal("kex_prop2buf: %s", ssh_err(r));
@ -330,6 +392,7 @@ static int input_gssapi_response(int type, u_int32_t, struct ssh *);
static int input_gssapi_token(int type, u_int32_t, struct ssh *);
static int input_gssapi_error(int, u_int32_t, struct ssh *);
static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
static int userauth_gsskeyex(struct ssh *);
#endif
void userauth(struct ssh *, char *);
@ -346,6 +409,11 @@ static char *authmethods_get(void);
Authmethod authmethods[] = {
#ifdef GSSAPI
{"gssapi-keyex",
userauth_gsskeyex,
NULL,
&options.gss_keyex,
NULL},
{"gssapi-with-mic",
userauth_gssapi,
userauth_gssapi_cleanup,
@ -716,12 +784,25 @@ userauth_gssapi(struct ssh *ssh)
OM_uint32 min;
int r, ok = 0;
gss_OID mech = NULL;
char *gss_host;
if (options.gss_server_identity)
gss_host = xstrdup(options.gss_server_identity);
else if (options.gss_trust_dns)
gss_host = remote_hostname(ssh);
else
gss_host = xstrdup(authctxt->host);
/* Try one GSSAPI method at a time, rather than sending them all at
* once. */
if (authctxt->gss_supported_mechs == NULL)
gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
if (GSS_ERROR(gss_indicate_mechs(&min,
&authctxt->gss_supported_mechs))) {
authctxt->gss_supported_mechs = NULL;
free(gss_host);
return 0;
}
/* Check to see whether the mechanism is usable before we offer it */
while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
@ -730,13 +811,15 @@ userauth_gssapi(struct ssh *ssh)
elements[authctxt->mech_tried];
/* My DER encoding requires length<128 */
if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
mech, authctxt->host)) {
mech, gss_host, options.gss_client_identity)) {
ok = 1; /* Mechanism works */
} else {
authctxt->mech_tried++;
}
}
free(gss_host);
if (!ok || mech == NULL)
return 0;
@ -976,6 +1059,55 @@ input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
free(lang);
return r;
}
int
userauth_gsskeyex(struct ssh *ssh)
{
struct sshbuf *b = NULL;
Authctxt *authctxt = ssh->authctxt;
gss_buffer_desc gssbuf;
gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
OM_uint32 ms;
int r;
static int attempt = 0;
if (attempt++ >= 1)
return (0);
if (gss_kex_context == NULL) {
debug("No valid Key exchange context");
return (0);
}
if ((b = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
ssh_gssapi_buildmic(b, authctxt->server_user, authctxt->service,
"gssapi-keyex");
if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
fatal("%s: sshbuf_mutable_ptr failed", __func__);
gssbuf.length = sshbuf_len(b);
if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) {
sshbuf_free(b);
return (0);
}
if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
(r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
(r = sshpkt_put_string(ssh, mic.value, mic.length)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("%s: %s", __func__, ssh_err(r));
sshbuf_free(b);
gss_release_buffer(&ms, &mic);
return (1);
}
#endif /* GSSAPI */
static int

62
sshd.c
View File

@ -817,8 +817,8 @@ notify_hostkeys(struct ssh *ssh)
}
debug3("%s: sent %u hostkeys", __func__, nkeys);
if (nkeys == 0)
fatal("%s: no hostkeys", __func__);
if ((r = sshpkt_send(ssh)) != 0)
debug3("%s: no hostkeys", __func__);
else if ((r = sshpkt_send(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: send", __func__);
sshbuf_free(buf);
}
@ -1852,7 +1852,8 @@ main(int ac, char **av)
free(fp);
}
accumulate_host_timing_secret(cfg, NULL);
if (!sensitive_data.have_ssh2_key) {
/* The GSSAPI key exchange can run without a host key */
if (!sensitive_data.have_ssh2_key && !options.gss_keyex) {
logit("sshd: no hostkeys available -- exiting.");
exit(1);
}
@ -2347,6 +2348,48 @@ do_ssh2_kex(struct ssh *ssh)
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
list_hostkey_types());
#if defined(GSSAPI) && defined(WITH_OPENSSL)
{
char *orig;
char *gss = NULL;
char *newstr = NULL;
orig = myproposal[PROPOSAL_KEX_ALGS];
/*
* If we don't have a host key, then there's no point advertising
* the other key exchange algorithms
*/
if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
orig = NULL;
if (options.gss_keyex)
gss = ssh_gssapi_server_mechanisms();
else
gss = NULL;
if (gss && orig)
xasprintf(&newstr, "%s,%s", gss, orig);
else if (gss)
newstr = gss;
else if (orig)
newstr = orig;
/*
* If we've got GSSAPI mechanisms, then we've got the 'null' host
* key alg, but we can't tell people about it unless its the only
* host key algorithm we support
*/
if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
if (newstr)
myproposal[PROPOSAL_KEX_ALGS] = newstr;
else
fatal("No supported key exchange algorithms");
}
#endif
/* start key exchange */
if ((r = kex_setup(ssh, myproposal)) != 0)
fatal("kex_setup: %s", ssh_err(r));
@ -2362,7 +2405,18 @@ do_ssh2_kex(struct ssh *ssh)
# ifdef OPENSSL_HAS_ECC
kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
# endif
#endif
# ifdef GSSAPI
if (options.gss_keyex) {
kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server;
kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server;
kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server;
kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server;
kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server;
}
# endif
#endif /* WITH_OPENSSL */
kex->kex[KEX_C25519_SHA256] = kex_gen_server;
kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server;
kex->load_host_public_key=&get_hostkey_public_by_type;

2
sshd_config
View File

@ -69,6 +69,8 @@ AuthorizedKeysFile .ssh/authorized_keys
# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no
# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will

30
sshd_config.5
View File

@ -646,6 +646,11 @@ Specifies whether to automatically destroy the user's credentials cache
on logout.
The default is
.Cm yes .
.It Cm GSSAPIKeyExchange
Specifies whether key exchange based on GSSAPI is allowed. GSSAPI key exchange
doesn't rely on ssh keys to verify host identity.
The default is
.Cm no .
.It Cm GSSAPIStrictAcceptorCheck
Determines whether to be strict about the identity of the GSSAPI acceptor
a client authenticates against.
@ -660,6 +665,31 @@ machine's default store.
This facility is provided to assist with operation on multi homed machines.
The default is
.Cm yes .
.It Cm GSSAPIStoreCredentialsOnRekey
Controls whether the user's GSSAPI credentials should be updated following a
successful connection rekeying. This option can be used to accepted renewed
or updated credentials from a compatible client. The default is
.Dq no .
.Pp
For this to work
.Cm GSSAPIKeyExchange
needs to be enabled in the server and also used by the client.
.It Cm GSSAPIKexAlgorithms
The list of key exchange algorithms that are accepted by GSSAPI
key exchange. Possible values are
.Bd -literal -offset 3n
gss-gex-sha1-,
gss-group1-sha1-,
gss-group14-sha1-,
gss-group14-sha256-,
gss-group16-sha512-,
gss-nistp256-sha256-,
gss-curve25519-sha256-
.Ed
.Pp
The default is
.Dq gss-gex-sha1-,gss-group14-sha1- .
This option only applies to protocol version 2 connections using GSSAPI.
.It Cm HostbasedAcceptedKeyTypes
Specifies the key types that will be accepted for hostbased authentication
as a list of comma-separated patterns.

3
sshkey.c
View File

@ -154,6 +154,7 @@ static const struct keytype keytypes[] = {
KEY_ECDSA_SK_CERT, NID_X9_62_prime256v1, 1, 0 },
# endif /* OPENSSL_HAS_ECC */
#endif /* WITH_OPENSSL */
{ "null", "null", NULL, KEY_NULL, 0, 0, 0 },
{ NULL, NULL, NULL, -1, -1, 0, 0 }
};
@ -255,7 +256,7 @@ sshkey_alg_list(int certs_only, int plain_only, int include_sigonly, char sep)
const struct keytype *kt;
for (kt = keytypes; kt->type != -1; kt++) {
if (kt->name == NULL)
if (kt->name == NULL || kt->type == KEY_NULL)
continue;
if (!include_sigonly && kt->sigonly)
continue;

1
sshkey.h
View File

@ -69,6 +69,7 @@ enum sshkey_types {
KEY_ECDSA_SK_CERT,
KEY_ED25519_SK,
KEY_ED25519_SK_CERT,
KEY_NULL,
KEY_UNSPEC
};