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openssh-portable/monitor.c

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/*
* Copyright 2002 Niels Provos <provos@citi.umich.edu>
* Copyright 2002 Markus Friedl <markus@openbsd.org>
* 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"
RCSID("$OpenBSD: monitor.c,v 1.30 2002/11/05 19:45:20 markus Exp $");
#include <openssl/dh.h>
#ifdef SKEY
#include <skey.h>
#endif
#include "ssh.h"
#include "auth.h"
#include "kex.h"
#include "dh.h"
#include "zlib.h"
#include "packet.h"
#include "auth-options.h"
#include "sshpty.h"
#include "channels.h"
#include "session.h"
#include "sshlogin.h"
#include "canohost.h"
#include "log.h"
#include "servconf.h"
#include "monitor.h"
#include "monitor_mm.h"
#include "monitor_wrap.h"
#include "monitor_fdpass.h"
#include "xmalloc.h"
#include "misc.h"
#include "buffer.h"
#include "bufaux.h"
#include "compat.h"
#include "ssh2.h"
#include "mpaux.h"
/* Imports */
extern ServerOptions options;
extern u_int utmp_len;
extern Newkeys *current_keys[];
extern z_stream incoming_stream;
extern z_stream outgoing_stream;
extern u_char session_id[];
extern Buffer input, output;
extern Buffer auth_debug;
extern int auth_debug_init;
/* State exported from the child */
struct {
z_stream incoming;
z_stream outgoing;
u_char *keyin;
u_int keyinlen;
u_char *keyout;
u_int keyoutlen;
u_char *ivin;
u_int ivinlen;
u_char *ivout;
u_int ivoutlen;
u_char *ssh1key;
u_int ssh1keylen;
int ssh1cipher;
int ssh1protoflags;
u_char *input;
u_int ilen;
u_char *output;
u_int olen;
} child_state;
/* Functions on the montior that answer unprivileged requests */
int mm_answer_moduli(int, Buffer *);
int mm_answer_sign(int, Buffer *);
int mm_answer_pwnamallow(int, Buffer *);
int mm_answer_auth2_read_banner(int, Buffer *);
int mm_answer_authserv(int, Buffer *);
int mm_answer_authpassword(int, Buffer *);
int mm_answer_bsdauthquery(int, Buffer *);
int mm_answer_bsdauthrespond(int, Buffer *);
int mm_answer_skeyquery(int, Buffer *);
int mm_answer_skeyrespond(int, Buffer *);
int mm_answer_keyallowed(int, Buffer *);
int mm_answer_keyverify(int, Buffer *);
int mm_answer_pty(int, Buffer *);
int mm_answer_pty_cleanup(int, Buffer *);
int mm_answer_term(int, Buffer *);
int mm_answer_rsa_keyallowed(int, Buffer *);
int mm_answer_rsa_challenge(int, Buffer *);
int mm_answer_rsa_response(int, Buffer *);
int mm_answer_sesskey(int, Buffer *);
int mm_answer_sessid(int, Buffer *);
#ifdef USE_PAM
int mm_answer_pam_start(int, Buffer *);
#endif
#ifdef KRB4
int mm_answer_krb4(int, Buffer *);
#endif
#ifdef KRB5
int mm_answer_krb5(int, Buffer *);
#endif
static Authctxt *authctxt;
static BIGNUM *ssh1_challenge = NULL; /* used for ssh1 rsa auth */
/* local state for key verify */
static u_char *key_blob = NULL;
static u_int key_bloblen = 0;
static int key_blobtype = MM_NOKEY;
static char *hostbased_cuser = NULL;
static char *hostbased_chost = NULL;
static char *auth_method = "unknown";
static int session_id2_len = 0;
static u_char *session_id2 = NULL;
struct mon_table {
enum monitor_reqtype type;
int flags;
int (*f)(int, Buffer *);
};
#define MON_ISAUTH 0x0004 /* Required for Authentication */
#define MON_AUTHDECIDE 0x0008 /* Decides Authentication */
#define MON_ONCE 0x0010 /* Disable after calling */
#define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE)
#define MON_PERMIT 0x1000 /* Request is permitted */
struct mon_table mon_dispatch_proto20[] = {
{MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
{MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign},
{MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow},
{MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv},
{MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner},
{MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword},
#ifdef USE_PAM
{MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start},
#endif
#ifdef BSD_AUTH
{MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
{MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH,mm_answer_bsdauthrespond},
#endif
#ifdef SKEY
{MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery},
{MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond},
#endif
{MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
{MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify},
{0, 0, NULL}
};
struct mon_table mon_dispatch_postauth20[] = {
{MONITOR_REQ_MODULI, 0, mm_answer_moduli},
{MONITOR_REQ_SIGN, 0, mm_answer_sign},
{MONITOR_REQ_PTY, 0, mm_answer_pty},
{MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup},
{MONITOR_REQ_TERM, 0, mm_answer_term},
{0, 0, NULL}
};
struct mon_table mon_dispatch_proto15[] = {
{MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow},
{MONITOR_REQ_SESSKEY, MON_ONCE, mm_answer_sesskey},
{MONITOR_REQ_SESSID, MON_ONCE, mm_answer_sessid},
{MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword},
{MONITOR_REQ_RSAKEYALLOWED, MON_ISAUTH, mm_answer_rsa_keyallowed},
{MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
{MONITOR_REQ_RSACHALLENGE, MON_ONCE, mm_answer_rsa_challenge},
{MONITOR_REQ_RSARESPONSE, MON_ONCE|MON_AUTHDECIDE, mm_answer_rsa_response},
#ifdef BSD_AUTH
{MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
{MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH,mm_answer_bsdauthrespond},
#endif
#ifdef SKEY
{MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery},
{MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond},
#endif
#ifdef USE_PAM
{MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start},
#endif
#ifdef KRB4
{MONITOR_REQ_KRB4, MON_ONCE|MON_AUTH, mm_answer_krb4},
#endif
#ifdef KRB5
{MONITOR_REQ_KRB5, MON_ONCE|MON_AUTH, mm_answer_krb5},
#endif
{0, 0, NULL}
};
struct mon_table mon_dispatch_postauth15[] = {
{MONITOR_REQ_PTY, MON_ONCE, mm_answer_pty},
{MONITOR_REQ_PTYCLEANUP, MON_ONCE, mm_answer_pty_cleanup},
{MONITOR_REQ_TERM, 0, mm_answer_term},
{0, 0, NULL}
};
struct mon_table *mon_dispatch;
/* Specifies if a certain message is allowed at the moment */
static void
monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit)
{
while (ent->f != NULL) {
if (ent->type == type) {
ent->flags &= ~MON_PERMIT;
ent->flags |= permit ? MON_PERMIT : 0;
return;
}
ent++;
}
}
static void
monitor_permit_authentications(int permit)
{
struct mon_table *ent = mon_dispatch;
while (ent->f != NULL) {
if (ent->flags & MON_AUTH) {
ent->flags &= ~MON_PERMIT;
ent->flags |= permit ? MON_PERMIT : 0;
}
ent++;
}
}
Authctxt *
monitor_child_preauth(struct monitor *pmonitor)
{
struct mon_table *ent;
int authenticated = 0;
debug3("preauth child monitor started");
if (compat20) {
mon_dispatch = mon_dispatch_proto20;
/* Permit requests for moduli and signatures */
monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
} else {
mon_dispatch = mon_dispatch_proto15;
monitor_permit(mon_dispatch, MONITOR_REQ_SESSKEY, 1);
}
authctxt = authctxt_new();
/* The first few requests do not require asynchronous access */
while (!authenticated) {
authenticated = monitor_read(pmonitor, mon_dispatch, &ent);
if (authenticated) {
if (!(ent->flags & MON_AUTHDECIDE))
fatal("%s: unexpected authentication from %d",
__func__, ent->type);
if (authctxt->pw->pw_uid == 0 &&
!auth_root_allowed(auth_method))
authenticated = 0;
#ifdef USE_PAM
if (!do_pam_account(authctxt->pw->pw_name, NULL))
authenticated = 0;
#endif
}
if (ent->flags & MON_AUTHDECIDE) {
auth_log(authctxt, authenticated, auth_method,
compat20 ? " ssh2" : "");
if (!authenticated)
authctxt->failures++;
}
}
if (!authctxt->valid)
fatal("%s: authenticated invalid user", __func__);
debug("%s: %s has been authenticated by privileged process",
__func__, authctxt->user);
mm_get_keystate(pmonitor);
return (authctxt);
}
void
monitor_child_postauth(struct monitor *pmonitor)
{
if (compat20) {
mon_dispatch = mon_dispatch_postauth20;
/* Permit requests for moduli and signatures */
monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
} else {
mon_dispatch = mon_dispatch_postauth15;
monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
}
if (!no_pty_flag) {
monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1);
}
for (;;)
monitor_read(pmonitor, mon_dispatch, NULL);
}
void
monitor_sync(struct monitor *pmonitor)
{
if (options.compression) {
/* The member allocation is not visible, so sync it */
mm_share_sync(&pmonitor->m_zlib, &pmonitor->m_zback);
}
}
int
monitor_read(struct monitor *pmonitor, struct mon_table *ent,
struct mon_table **pent)
{
Buffer m;
int ret;
u_char type;
buffer_init(&m);
mm_request_receive(pmonitor->m_sendfd, &m);
type = buffer_get_char(&m);
debug3("%s: checking request %d", __func__, type);
while (ent->f != NULL) {
if (ent->type == type)
break;
ent++;
}
if (ent->f != NULL) {
if (!(ent->flags & MON_PERMIT))
fatal("%s: unpermitted request %d", __func__,
type);
ret = (*ent->f)(pmonitor->m_sendfd, &m);
buffer_free(&m);
/* The child may use this request only once, disable it */
if (ent->flags & MON_ONCE) {
debug2("%s: %d used once, disabling now", __func__,
type);
ent->flags &= ~MON_PERMIT;
}
if (pent != NULL)
*pent = ent;
return ret;
}
fatal("%s: unsupported request: %d", __func__, type);
/* NOTREACHED */
return (-1);
}
/* allowed key state */
static int
monitor_allowed_key(u_char *blob, u_int bloblen)
{
/* make sure key is allowed */
if (key_blob == NULL || key_bloblen != bloblen ||
memcmp(key_blob, blob, key_bloblen))
return (0);
return (1);
}
static void
monitor_reset_key_state(void)
{
/* reset state */
if (key_blob != NULL)
xfree(key_blob);
if (hostbased_cuser != NULL)
xfree(hostbased_cuser);
if (hostbased_chost != NULL)
xfree(hostbased_chost);
key_blob = NULL;
key_bloblen = 0;
key_blobtype = MM_NOKEY;
hostbased_cuser = NULL;
hostbased_chost = NULL;
}
int
mm_answer_moduli(int socket, Buffer *m)
{
DH *dh;
int min, want, max;
min = buffer_get_int(m);
want = buffer_get_int(m);
max = buffer_get_int(m);
debug3("%s: got parameters: %d %d %d",
__func__, min, want, max);
/* We need to check here, too, in case the child got corrupted */
if (max < min || want < min || max < want)
fatal("%s: bad parameters: %d %d %d",
__func__, min, want, max);
buffer_clear(m);
dh = choose_dh(min, want, max);
if (dh == NULL) {
buffer_put_char(m, 0);
return (0);
} else {
/* Send first bignum */
buffer_put_char(m, 1);
buffer_put_bignum2(m, dh->p);
buffer_put_bignum2(m, dh->g);
DH_free(dh);
}
mm_request_send(socket, MONITOR_ANS_MODULI, m);
return (0);
}
int
mm_answer_sign(int socket, Buffer *m)
{
Key *key;
u_char *p;
u_char *signature;
u_int siglen, datlen;
int keyid;
debug3("%s", __func__);
keyid = buffer_get_int(m);
p = buffer_get_string(m, &datlen);
if (datlen != 20)
fatal("%s: data length incorrect: %u", __func__, datlen);
/* save session id, it will be passed on the first call */
if (session_id2_len == 0) {
session_id2_len = datlen;
session_id2 = xmalloc(session_id2_len);
memcpy(session_id2, p, session_id2_len);
}
if ((key = get_hostkey_by_index(keyid)) == NULL)
fatal("%s: no hostkey from index %d", __func__, keyid);
if (key_sign(key, &signature, &siglen, p, datlen) < 0)
fatal("%s: key_sign failed", __func__);
debug3("%s: signature %p(%u)", __func__, signature, siglen);
buffer_clear(m);
buffer_put_string(m, signature, siglen);
xfree(p);
xfree(signature);
mm_request_send(socket, MONITOR_ANS_SIGN, m);
/* Turn on permissions for getpwnam */
monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
return (0);
}
/* Retrieves the password entry and also checks if the user is permitted */
int
mm_answer_pwnamallow(int socket, Buffer *m)
{
char *login;
struct passwd *pwent;
int allowed = 0;
debug3("%s", __func__);
if (authctxt->attempt++ != 0)
fatal("%s: multiple attempts for getpwnam", __func__);
login = buffer_get_string(m, NULL);
pwent = getpwnamallow(login);
authctxt->user = xstrdup(login);
setproctitle("%s [priv]", pwent ? login : "unknown");
xfree(login);
buffer_clear(m);
if (pwent == NULL) {
buffer_put_char(m, 0);
goto out;
}
allowed = 1;
authctxt->pw = pwent;
authctxt->valid = 1;
buffer_put_char(m, 1);
buffer_put_string(m, pwent, sizeof(struct passwd));
buffer_put_cstring(m, pwent->pw_name);
buffer_put_cstring(m, "*");
buffer_put_cstring(m, pwent->pw_gecos);
#ifdef HAVE_PW_CLASS_IN_PASSWD
buffer_put_cstring(m, pwent->pw_class);
#endif
buffer_put_cstring(m, pwent->pw_dir);
buffer_put_cstring(m, pwent->pw_shell);
out:
debug3("%s: sending MONITOR_ANS_PWNAM: %d", __func__, allowed);
mm_request_send(socket, MONITOR_ANS_PWNAM, m);
/* For SSHv1 allow authentication now */
if (!compat20)
monitor_permit_authentications(1);
else {
/* Allow service/style information on the auth context */
monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1);
}
#ifdef USE_PAM
monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
#endif
return (0);
}
int mm_answer_auth2_read_banner(int socket, Buffer *m)
{
char *banner;
buffer_clear(m);
banner = auth2_read_banner();
buffer_put_cstring(m, banner != NULL ? banner : "");
mm_request_send(socket, MONITOR_ANS_AUTH2_READ_BANNER, m);
if (banner != NULL)
xfree(banner);
return (0);
}
int
mm_answer_authserv(int socket, Buffer *m)
{
monitor_permit_authentications(1);
authctxt->service = buffer_get_string(m, NULL);
authctxt->style = buffer_get_string(m, NULL);
debug3("%s: service=%s, style=%s",
__func__, authctxt->service, authctxt->style);
if (strlen(authctxt->style) == 0) {
xfree(authctxt->style);
authctxt->style = NULL;
}
return (0);
}
int
mm_answer_authpassword(int socket, Buffer *m)
{
static int call_count;
char *passwd;
int authenticated;
u_int plen;
passwd = buffer_get_string(m, &plen);
/* Only authenticate if the context is valid */
authenticated = options.password_authentication &&
authctxt->valid && auth_password(authctxt, passwd);
memset(passwd, 0, strlen(passwd));
xfree(passwd);
buffer_clear(m);
buffer_put_int(m, authenticated);
debug3("%s: sending result %d", __func__, authenticated);
mm_request_send(socket, MONITOR_ANS_AUTHPASSWORD, m);
call_count++;
if (plen == 0 && call_count == 1)
auth_method = "none";
else
auth_method = "password";
/* Causes monitor loop to terminate if authenticated */
return (authenticated);
}
#ifdef BSD_AUTH
int
mm_answer_bsdauthquery(int socket, Buffer *m)
{
char *name, *infotxt;
u_int numprompts;
u_int *echo_on;
char **prompts;
int res;
res = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
&prompts, &echo_on);
buffer_clear(m);
buffer_put_int(m, res);
if (res != -1)
buffer_put_cstring(m, prompts[0]);
debug3("%s: sending challenge res: %d", __func__, res);
mm_request_send(socket, MONITOR_ANS_BSDAUTHQUERY, m);
if (res != -1) {
xfree(name);
xfree(infotxt);
xfree(prompts);
xfree(echo_on);
}
return (0);
}
int
mm_answer_bsdauthrespond(int socket, Buffer *m)
{
char *response;
int authok;
if (authctxt->as == 0)
fatal("%s: no bsd auth session", __func__);
response = buffer_get_string(m, NULL);
authok = options.challenge_response_authentication &&
auth_userresponse(authctxt->as, response, 0);
authctxt->as = NULL;
debug3("%s: <%s> = <%d>", __func__, response, authok);
xfree(response);
buffer_clear(m);
buffer_put_int(m, authok);
debug3("%s: sending authenticated: %d", __func__, authok);
mm_request_send(socket, MONITOR_ANS_BSDAUTHRESPOND, m);
auth_method = "bsdauth";
return (authok != 0);
}
#endif
#ifdef SKEY
int
mm_answer_skeyquery(int socket, Buffer *m)
{
struct skey skey;
char challenge[1024];
int res;
res = skeychallenge(&skey, authctxt->user, challenge);
buffer_clear(m);
buffer_put_int(m, res);
if (res != -1)
buffer_put_cstring(m, challenge);
debug3("%s: sending challenge res: %d", __func__, res);
mm_request_send(socket, MONITOR_ANS_SKEYQUERY, m);
return (0);
}
int
mm_answer_skeyrespond(int socket, Buffer *m)
{
char *response;
int authok;
response = buffer_get_string(m, NULL);
authok = (options.challenge_response_authentication &&
authctxt->valid &&
skey_haskey(authctxt->pw->pw_name) == 0 &&
skey_passcheck(authctxt->pw->pw_name, response) != -1);
xfree(response);
buffer_clear(m);
buffer_put_int(m, authok);
debug3("%s: sending authenticated: %d", __func__, authok);
mm_request_send(socket, MONITOR_ANS_SKEYRESPOND, m);
auth_method = "skey";
return (authok != 0);
}
#endif
#ifdef USE_PAM
int
mm_answer_pam_start(int socket, Buffer *m)
{
char *user;
user = buffer_get_string(m, NULL);
start_pam(user);
xfree(user);
return (0);
}
#endif
static void
mm_append_debug(Buffer *m)
{
if (auth_debug_init && buffer_len(&auth_debug)) {
debug3("%s: Appending debug messages for child", __func__);
buffer_append(m, buffer_ptr(&auth_debug),
buffer_len(&auth_debug));
buffer_clear(&auth_debug);
}
}
int
mm_answer_keyallowed(int socket, Buffer *m)
{
Key *key;
char *cuser, *chost;
u_char *blob;
u_int bloblen;
enum mm_keytype type = 0;
int allowed = 0;
debug3("%s entering", __func__);
type = buffer_get_int(m);
cuser = buffer_get_string(m, NULL);
chost = buffer_get_string(m, NULL);
blob = buffer_get_string(m, &bloblen);
key = key_from_blob(blob, bloblen);
if ((compat20 && type == MM_RSAHOSTKEY) ||
(!compat20 && type != MM_RSAHOSTKEY))
fatal("%s: key type and protocol mismatch", __func__);
debug3("%s: key_from_blob: %p", __func__, key);
if (key != NULL && authctxt->pw != NULL) {
switch(type) {
case MM_USERKEY:
allowed = options.pubkey_authentication &&
user_key_allowed(authctxt->pw, key);
break;
case MM_HOSTKEY:
allowed = options.hostbased_authentication &&
hostbased_key_allowed(authctxt->pw,
cuser, chost, key);
break;
case MM_RSAHOSTKEY:
key->type = KEY_RSA1; /* XXX */
allowed = options.rhosts_rsa_authentication &&
auth_rhosts_rsa_key_allowed(authctxt->pw,
cuser, chost, key);
break;
default:
fatal("%s: unknown key type %d", __func__, type);
break;
}
key_free(key);
}
/* clear temporarily storage (used by verify) */
monitor_reset_key_state();
if (allowed) {
/* Save temporarily for comparison in verify */
key_blob = blob;
key_bloblen = bloblen;
key_blobtype = type;
hostbased_cuser = cuser;
hostbased_chost = chost;
}
debug3("%s: key %p is %s",
__func__, key, allowed ? "allowed" : "disallowed");
buffer_clear(m);
buffer_put_int(m, allowed);
mm_append_debug(m);
mm_request_send(socket, MONITOR_ANS_KEYALLOWED, m);
if (type == MM_RSAHOSTKEY)
monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed);
return (0);
}
static int
monitor_valid_userblob(u_char *data, u_int datalen)
{
Buffer b;
char *p;
u_int len;
int fail = 0;
buffer_init(&b);
buffer_append(&b, data, datalen);
if (datafellows & SSH_OLD_SESSIONID) {
p = buffer_ptr(&b);
len = buffer_len(&b);
if ((session_id2 == NULL) ||
(len < session_id2_len) ||
(memcmp(p, session_id2, session_id2_len) != 0))
fail++;
buffer_consume(&b, session_id2_len);
} else {
p = buffer_get_string(&b, &len);
if ((session_id2 == NULL) ||
(len != session_id2_len) ||
(memcmp(p, session_id2, session_id2_len) != 0))
fail++;
xfree(p);
}
if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
fail++;
p = buffer_get_string(&b, NULL);
if (strcmp(authctxt->user, p) != 0) {
log("wrong user name passed to monitor: expected %s != %.100s",
authctxt->user, p);
fail++;
}
xfree(p);
buffer_skip_string(&b);
if (datafellows & SSH_BUG_PKAUTH) {
if (!buffer_get_char(&b))
fail++;
} else {
p = buffer_get_string(&b, NULL);
if (strcmp("publickey", p) != 0)
fail++;
xfree(p);
if (!buffer_get_char(&b))
fail++;
buffer_skip_string(&b);
}
buffer_skip_string(&b);
if (buffer_len(&b) != 0)
fail++;
buffer_free(&b);
return (fail == 0);
}
static int
monitor_valid_hostbasedblob(u_char *data, u_int datalen, char *cuser,
char *chost)
{
Buffer b;
char *p;
u_int len;
int fail = 0;
buffer_init(&b);
buffer_append(&b, data, datalen);
p = buffer_get_string(&b, &len);
if ((session_id2 == NULL) ||
(len != session_id2_len) ||
(memcmp(p, session_id2, session_id2_len) != 0))
fail++;
xfree(p);
if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
fail++;
p = buffer_get_string(&b, NULL);
if (strcmp(authctxt->user, p) != 0) {
log("wrong user name passed to monitor: expected %s != %.100s",
authctxt->user, p);
fail++;
}
xfree(p);
buffer_skip_string(&b); /* service */
p = buffer_get_string(&b, NULL);
if (strcmp(p, "hostbased") != 0)
fail++;
xfree(p);
buffer_skip_string(&b); /* pkalg */
buffer_skip_string(&b); /* pkblob */
/* verify client host, strip trailing dot if necessary */
p = buffer_get_string(&b, NULL);
if (((len = strlen(p)) > 0) && p[len - 1] == '.')
p[len - 1] = '\0';
if (strcmp(p, chost) != 0)
fail++;
xfree(p);
/* verify client user */
p = buffer_get_string(&b, NULL);
if (strcmp(p, cuser) != 0)
fail++;
xfree(p);
if (buffer_len(&b) != 0)
fail++;
buffer_free(&b);
return (fail == 0);
}
int
mm_answer_keyverify(int socket, Buffer *m)
{
Key *key;
u_char *signature, *data, *blob;
u_int signaturelen, datalen, bloblen;
int verified = 0;
int valid_data = 0;
blob = buffer_get_string(m, &bloblen);
signature = buffer_get_string(m, &signaturelen);
data = buffer_get_string(m, &datalen);
if (hostbased_cuser == NULL || hostbased_chost == NULL ||
!monitor_allowed_key(blob, bloblen))
fatal("%s: bad key, not previously allowed", __func__);
key = key_from_blob(blob, bloblen);
if (key == NULL)
fatal("%s: bad public key blob", __func__);
switch (key_blobtype) {
case MM_USERKEY:
valid_data = monitor_valid_userblob(data, datalen);
break;
case MM_HOSTKEY:
valid_data = monitor_valid_hostbasedblob(data, datalen,
hostbased_cuser, hostbased_chost);
break;
default:
valid_data = 0;
break;
}
if (!valid_data)
fatal("%s: bad signature data blob", __func__);
verified = key_verify(key, signature, signaturelen, data, datalen);
debug3("%s: key %p signature %s",
__func__, key, verified ? "verified" : "unverified");
key_free(key);
xfree(blob);
xfree(signature);
xfree(data);
auth_method = key_blobtype == MM_USERKEY ? "publickey" : "hostbased";
monitor_reset_key_state();
buffer_clear(m);
buffer_put_int(m, verified);
mm_request_send(socket, MONITOR_ANS_KEYVERIFY, m);
return (verified);
}
static void
mm_record_login(Session *s, struct passwd *pw)
{
socklen_t fromlen;
struct sockaddr_storage from;
/*
* Get IP address of client. If the connection is not a socket, let
* the address be 0.0.0.0.
*/
memset(&from, 0, sizeof(from));
fromlen = sizeof(from);
if (packet_connection_is_on_socket()) {
if (getpeername(packet_get_connection_in(),
(struct sockaddr *) & from, &fromlen) < 0) {
debug("getpeername: %.100s", strerror(errno));
fatal_cleanup();
}
}
/* Record that there was a login on that tty from the remote host. */
record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid,
get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping),
(struct sockaddr *)&from, fromlen);
}
static void
mm_session_close(Session *s)
{
debug3("%s: session %d pid %d", __func__, s->self, s->pid);
if (s->ttyfd != -1) {
debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ptyfd);
fatal_remove_cleanup(session_pty_cleanup2, (void *)s);
session_pty_cleanup2(s);
}
s->used = 0;
}
int
mm_answer_pty(int socket, Buffer *m)
{
extern struct monitor *pmonitor;
Session *s;
int res, fd0;
debug3("%s entering", __func__);
buffer_clear(m);
s = session_new();
if (s == NULL)
goto error;
s->authctxt = authctxt;
s->pw = authctxt->pw;
s->pid = pmonitor->m_pid;
res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
if (res == 0)
goto error;
fatal_add_cleanup(session_pty_cleanup2, (void *)s);
pty_setowner(authctxt->pw, s->tty);
buffer_put_int(m, 1);
buffer_put_cstring(m, s->tty);
mm_request_send(socket, MONITOR_ANS_PTY, m);
mm_send_fd(socket, s->ptyfd);
mm_send_fd(socket, s->ttyfd);
/* We need to trick ttyslot */
if (dup2(s->ttyfd, 0) == -1)
fatal("%s: dup2", __func__);
mm_record_login(s, authctxt->pw);
/* Now we can close the file descriptor again */
close(0);
/* make sure nothing uses fd 0 */
if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) < 0)
fatal("%s: open(/dev/null): %s", __func__, strerror(errno));
if (fd0 != 0)
error("%s: fd0 %d != 0", __func__, fd0);
/* slave is not needed */
close(s->ttyfd);
s->ttyfd = s->ptyfd;
/* no need to dup() because nobody closes ptyfd */
s->ptymaster = s->ptyfd;
debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ttyfd);
return (0);
error:
if (s != NULL)
mm_session_close(s);
buffer_put_int(m, 0);
mm_request_send(socket, MONITOR_ANS_PTY, m);
return (0);
}
int
mm_answer_pty_cleanup(int socket, Buffer *m)
{
Session *s;
char *tty;
debug3("%s entering", __func__);
tty = buffer_get_string(m, NULL);
if ((s = session_by_tty(tty)) != NULL)
mm_session_close(s);
buffer_clear(m);
xfree(tty);
return (0);
}
int
mm_answer_sesskey(int socket, Buffer *m)
{
BIGNUM *p;
int rsafail;
/* Turn off permissions */
monitor_permit(mon_dispatch, MONITOR_REQ_SESSKEY, 1);
if ((p = BN_new()) == NULL)
fatal("%s: BN_new", __func__);
buffer_get_bignum2(m, p);
rsafail = ssh1_session_key(p);
buffer_clear(m);
buffer_put_int(m, rsafail);
buffer_put_bignum2(m, p);
BN_clear_free(p);
mm_request_send(socket, MONITOR_ANS_SESSKEY, m);
/* Turn on permissions for sessid passing */
monitor_permit(mon_dispatch, MONITOR_REQ_SESSID, 1);
return (0);
}
int
mm_answer_sessid(int socket, Buffer *m)
{
int i;
debug3("%s entering", __func__);
if (buffer_len(m) != 16)
fatal("%s: bad ssh1 session id", __func__);
for (i = 0; i < 16; i++)
session_id[i] = buffer_get_char(m);
/* Turn on permissions for getpwnam */
monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
return (0);
}
int
mm_answer_rsa_keyallowed(int socket, Buffer *m)
{
BIGNUM *client_n;
Key *key = NULL;
u_char *blob = NULL;
u_int blen = 0;
int allowed = 0;
debug3("%s entering", __func__);
if (options.rsa_authentication && authctxt->valid) {
if ((client_n = BN_new()) == NULL)
fatal("%s: BN_new", __func__);
buffer_get_bignum2(m, client_n);
allowed = auth_rsa_key_allowed(authctxt->pw, client_n, &key);
BN_clear_free(client_n);
}
buffer_clear(m);
buffer_put_int(m, allowed);
/* clear temporarily storage (used by generate challenge) */
monitor_reset_key_state();
if (allowed && key != NULL) {
key->type = KEY_RSA; /* cheat for key_to_blob */
if (key_to_blob(key, &blob, &blen) == 0)
fatal("%s: key_to_blob failed", __func__);
buffer_put_string(m, blob, blen);
/* Save temporarily for comparison in verify */
key_blob = blob;
key_bloblen = blen;
key_blobtype = MM_RSAUSERKEY;
key_free(key);
}
mm_append_debug(m);
mm_request_send(socket, MONITOR_ANS_RSAKEYALLOWED, m);
monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed);
monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 0);
return (0);
}
int
mm_answer_rsa_challenge(int socket, Buffer *m)
{
Key *key = NULL;
u_char *blob;
u_int blen;
debug3("%s entering", __func__);
if (!authctxt->valid)
fatal("%s: authctxt not valid", __func__);
blob = buffer_get_string(m, &blen);
if (!monitor_allowed_key(blob, blen))
fatal("%s: bad key, not previously allowed", __func__);
if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
fatal("%s: key type mismatch", __func__);
if ((key = key_from_blob(blob, blen)) == NULL)
fatal("%s: received bad key", __func__);
if (ssh1_challenge)
BN_clear_free(ssh1_challenge);
ssh1_challenge = auth_rsa_generate_challenge(key);
buffer_clear(m);
buffer_put_bignum2(m, ssh1_challenge);
debug3("%s sending reply", __func__);
mm_request_send(socket, MONITOR_ANS_RSACHALLENGE, m);
monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 1);
return (0);
}
int
mm_answer_rsa_response(int socket, Buffer *m)
{
Key *key = NULL;
u_char *blob, *response;
u_int blen, len;
int success;
debug3("%s entering", __func__);
if (!authctxt->valid)
fatal("%s: authctxt not valid", __func__);
if (ssh1_challenge == NULL)
fatal("%s: no ssh1_challenge", __func__);
blob = buffer_get_string(m, &blen);
if (!monitor_allowed_key(blob, blen))
fatal("%s: bad key, not previously allowed", __func__);
if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
fatal("%s: key type mismatch: %d", __func__, key_blobtype);
if ((key = key_from_blob(blob, blen)) == NULL)
fatal("%s: received bad key", __func__);
response = buffer_get_string(m, &len);
if (len != 16)
fatal("%s: received bad response to challenge", __func__);
success = auth_rsa_verify_response(key, ssh1_challenge, response);
key_free(key);
xfree(response);
auth_method = key_blobtype == MM_RSAUSERKEY ? "rsa" : "rhosts-rsa";
/* reset state */
BN_clear_free(ssh1_challenge);
ssh1_challenge = NULL;
monitor_reset_key_state();
buffer_clear(m);
buffer_put_int(m, success);
mm_request_send(socket, MONITOR_ANS_RSARESPONSE, m);
return (success);
}
#ifdef KRB4
int
mm_answer_krb4(int socket, Buffer *m)
{
KTEXT_ST auth, reply;
char *client, *p;
int success;
u_int alen;
reply.length = auth.length = 0;
p = buffer_get_string(m, &alen);
if (alen >= MAX_KTXT_LEN)
fatal("%s: auth too large", __func__);
memcpy(auth.dat, p, alen);
auth.length = alen;
memset(p, 0, alen);
xfree(p);
success = options.kerberos_authentication &&
authctxt->valid &&
auth_krb4(authctxt, &auth, &client, &reply);
memset(auth.dat, 0, alen);
buffer_clear(m);
buffer_put_int(m, success);
if (success) {
buffer_put_cstring(m, client);
buffer_put_string(m, reply.dat, reply.length);
if (client)
xfree(client);
if (reply.length)
memset(reply.dat, 0, reply.length);
}
debug3("%s: sending result %d", __func__, success);
mm_request_send(socket, MONITOR_ANS_KRB4, m);
auth_method = "kerberos";
/* Causes monitor loop to terminate if authenticated */
return (success);
}
#endif
#ifdef KRB5
int
mm_answer_krb5(int socket, Buffer *m)
{
krb5_data tkt, reply;
char *client_user;
u_int len;
int success;
/* use temporary var to avoid size issues on 64bit arch */
tkt.data = buffer_get_string(m, &len);
tkt.length = len;
success = options.kerberos_authentication &&
authctxt->valid &&
auth_krb5(authctxt, &tkt, &client_user, &reply);
if (tkt.length)
xfree(tkt.data);
buffer_clear(m);
buffer_put_int(m, success);
if (success) {
buffer_put_cstring(m, client_user);
buffer_put_string(m, reply.data, reply.length);
if (client_user)
xfree(client_user);
if (reply.length)
xfree(reply.data);
}
mm_request_send(socket, MONITOR_ANS_KRB5, m);
return success;
}
#endif
int
mm_answer_term(int socket, Buffer *req)
{
extern struct monitor *pmonitor;
int res, status;
debug3("%s: tearing down sessions", __func__);
/* The child is terminating */
session_destroy_all(&mm_session_close);
while (waitpid(pmonitor->m_pid, &status, 0) == -1)
if (errno != EINTR)
exit(1);
res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;
/* Terminate process */
exit (res);
}
void
monitor_apply_keystate(struct monitor *pmonitor)
{
if (compat20) {
set_newkeys(MODE_IN);
set_newkeys(MODE_OUT);
} else {
packet_set_protocol_flags(child_state.ssh1protoflags);
packet_set_encryption_key(child_state.ssh1key,
child_state.ssh1keylen, child_state.ssh1cipher);
xfree(child_state.ssh1key);
}
/* for rc4 and other stateful ciphers */
packet_set_keycontext(MODE_OUT, child_state.keyout);
xfree(child_state.keyout);
packet_set_keycontext(MODE_IN, child_state.keyin);
xfree(child_state.keyin);
if (!compat20) {
packet_set_iv(MODE_OUT, child_state.ivout);
xfree(child_state.ivout);
packet_set_iv(MODE_IN, child_state.ivin);
xfree(child_state.ivin);
}
memcpy(&incoming_stream, &child_state.incoming,
sizeof(incoming_stream));
memcpy(&outgoing_stream, &child_state.outgoing,
sizeof(outgoing_stream));
/* Update with new address */
if (options.compression)
mm_init_compression(pmonitor->m_zlib);
/* Network I/O buffers */
/* XXX inefficient for large buffers, need: buffer_init_from_string */
buffer_clear(&input);
buffer_append(&input, child_state.input, child_state.ilen);
memset(child_state.input, 0, child_state.ilen);
xfree(child_state.input);
buffer_clear(&output);
buffer_append(&output, child_state.output, child_state.olen);
memset(child_state.output, 0, child_state.olen);
xfree(child_state.output);
}
static Kex *
mm_get_kex(Buffer *m)
{
Kex *kex;
void *blob;
u_int bloblen;
kex = xmalloc(sizeof(*kex));
memset(kex, 0, sizeof(*kex));
kex->session_id = buffer_get_string(m, &kex->session_id_len);
if ((session_id2 == NULL) ||
(kex->session_id_len != session_id2_len) ||
(memcmp(kex->session_id, session_id2, session_id2_len) != 0))
fatal("mm_get_get: internal error: bad session id");
kex->we_need = buffer_get_int(m);
kex->server = 1;
kex->hostkey_type = buffer_get_int(m);
kex->kex_type = buffer_get_int(m);
blob = buffer_get_string(m, &bloblen);
buffer_init(&kex->my);
buffer_append(&kex->my, blob, bloblen);
xfree(blob);
blob = buffer_get_string(m, &bloblen);
buffer_init(&kex->peer);
buffer_append(&kex->peer, blob, bloblen);
xfree(blob);
kex->done = 1;
kex->flags = buffer_get_int(m);
kex->client_version_string = buffer_get_string(m, NULL);
kex->server_version_string = buffer_get_string(m, NULL);
kex->load_host_key=&get_hostkey_by_type;
kex->host_key_index=&get_hostkey_index;
return (kex);
}
/* This function requries careful sanity checking */
void
mm_get_keystate(struct monitor *pmonitor)
{
Buffer m;
u_char *blob, *p;
u_int bloblen, plen;
debug3("%s: Waiting for new keys", __func__);
buffer_init(&m);
mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, &m);
if (!compat20) {
child_state.ssh1protoflags = buffer_get_int(&m);
child_state.ssh1cipher = buffer_get_int(&m);
child_state.ssh1key = buffer_get_string(&m,
&child_state.ssh1keylen);
child_state.ivout = buffer_get_string(&m,
&child_state.ivoutlen);
child_state.ivin = buffer_get_string(&m, &child_state.ivinlen);
goto skip;
} else {
/* Get the Kex for rekeying */
*pmonitor->m_pkex = mm_get_kex(&m);
}
blob = buffer_get_string(&m, &bloblen);
current_keys[MODE_OUT] = mm_newkeys_from_blob(blob, bloblen);
xfree(blob);
debug3("%s: Waiting for second key", __func__);
blob = buffer_get_string(&m, &bloblen);
current_keys[MODE_IN] = mm_newkeys_from_blob(blob, bloblen);
xfree(blob);
/* Now get sequence numbers for the packets */
packet_set_seqnr(MODE_OUT, buffer_get_int(&m));
packet_set_seqnr(MODE_IN, buffer_get_int(&m));
skip:
/* Get the key context */
child_state.keyout = buffer_get_string(&m, &child_state.keyoutlen);
child_state.keyin = buffer_get_string(&m, &child_state.keyinlen);
debug3("%s: Getting compression state", __func__);
/* Get compression state */
p = buffer_get_string(&m, &plen);
if (plen != sizeof(child_state.outgoing))
fatal("%s: bad request size", __func__);
memcpy(&child_state.outgoing, p, sizeof(child_state.outgoing));
xfree(p);
p = buffer_get_string(&m, &plen);
if (plen != sizeof(child_state.incoming))
fatal("%s: bad request size", __func__);
memcpy(&child_state.incoming, p, sizeof(child_state.incoming));
xfree(p);
/* Network I/O buffers */
debug3("%s: Getting Network I/O buffers", __func__);
child_state.input = buffer_get_string(&m, &child_state.ilen);
child_state.output = buffer_get_string(&m, &child_state.olen);
buffer_free(&m);
}
/* Allocation functions for zlib */
void *
mm_zalloc(struct mm_master *mm, u_int ncount, u_int size)
{
size_t len = (size_t) size * ncount;
void *address;
if (len == 0 || ncount > SIZE_T_MAX / size)
fatal("%s: mm_zalloc(%u, %u)", __func__, ncount, size);
address = mm_malloc(mm, len);
return (address);
}
void
mm_zfree(struct mm_master *mm, void *address)
{
mm_free(mm, address);
}
void
mm_init_compression(struct mm_master *mm)
{
outgoing_stream.zalloc = (alloc_func)mm_zalloc;
outgoing_stream.zfree = (free_func)mm_zfree;
outgoing_stream.opaque = mm;
incoming_stream.zalloc = (alloc_func)mm_zalloc;
incoming_stream.zfree = (free_func)mm_zfree;
incoming_stream.opaque = mm;
}
/* XXX */
#define FD_CLOSEONEXEC(x) do { \
if (fcntl(x, F_SETFD, 1) == -1) \
fatal("fcntl(%d, F_SETFD)", x); \
} while (0)
static void
monitor_socketpair(int *pair)
{
#ifdef HAVE_SOCKETPAIR
if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
fatal("%s: socketpair", __func__);
#else
fatal("%s: UsePrivilegeSeparation=yes not supported",
__func__);
#endif
FD_CLOSEONEXEC(pair[0]);
FD_CLOSEONEXEC(pair[1]);
}
#define MM_MEMSIZE 65536
struct monitor *
monitor_init(void)
{
struct monitor *mon;
int pair[2];
mon = xmalloc(sizeof(*mon));
monitor_socketpair(pair);
mon->m_recvfd = pair[0];
mon->m_sendfd = pair[1];
/* Used to share zlib space across processes */
if (options.compression) {
mon->m_zback = mm_create(NULL, MM_MEMSIZE);
mon->m_zlib = mm_create(mon->m_zback, 20 * MM_MEMSIZE);
/* Compression needs to share state across borders */
mm_init_compression(mon->m_zlib);
}
return mon;
}
void
monitor_reinit(struct monitor *mon)
{
int pair[2];
monitor_socketpair(pair);
mon->m_recvfd = pair[0];
mon->m_sendfd = pair[1];
}
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