/* $NetBSD: monitor.c,v 1.35 2020/12/04 18:42:50 christos Exp $ */
/* $OpenBSD: monitor.c,v 1.214 2020/08/27 01:07:09 djm Exp $ */
/*
* 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("$NetBSD: monitor.c,v 1.35 2020/12/04 18:42:50 christos Exp $");
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/tree.h>
#include <sys/queue.h>
#ifdef WITH_OPENSSL
#include <openssl/dh.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <paths.h>
#include <poll.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <unistd.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "atomicio.h"
#include "xmalloc.h"
#include "ssh.h"
#include "sshkey.h"
#include "sshbuf.h"
#include "hostfile.h"
#include "auth.h"
#include "cipher.h"
#include "kex.h"
#include "dh.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 "misc.h"
#include "servconf.h"
#include "monitor.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "monitor_fdpass.h"
#include "compat.h"
#include "ssh2.h"
#include "authfd.h"
#include "match.h"
#include "ssherr.h"
#include "sk-api.h"
#include "pfilter.h"
#ifdef GSSAPI
static Gssctxt *gsscontext = NULL;
#endif
/* Imports */
extern ServerOptions options;
extern u_int utmp_len;
extern u_char session_id[];
extern struct sshbuf *loginmsg;
extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */
/* State exported from the child */
static struct sshbuf *child_state;
/* Functions on the monitor that answer unprivileged requests */
int mm_answer_moduli(struct ssh *, int, struct sshbuf *);
int mm_answer_sign(struct ssh *, int, struct sshbuf *);
int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *);
int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *);
int mm_answer_authserv(struct ssh *, int, struct sshbuf *);
int mm_answer_authpassword(struct ssh *, int, struct sshbuf *);
int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *);
int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *);
int mm_answer_skeyquery(struct ssh *, int, struct sshbuf *);
int mm_answer_skeyrespond(struct ssh *, int, struct sshbuf *);
int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *);
int mm_answer_keyverify(struct ssh *, int, struct sshbuf *);
int mm_answer_pty(struct ssh *, int, struct sshbuf *);
int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *);
int mm_answer_term(struct ssh *, int, struct sshbuf *);
int mm_answer_rsa_keyallowed(struct ssh *, int, struct sshbuf *);
int mm_answer_rsa_challenge(struct ssh *, int, struct sshbuf *);
int mm_answer_rsa_response(struct ssh *, int, struct sshbuf *);
int mm_answer_sesskey(struct ssh *, int, struct sshbuf *);
int mm_answer_sessid(struct ssh *, int, struct sshbuf *);
#ifdef USE_PAM
int mm_answer_pam_start(struct ssh *, int, struct sshbuf *);
int mm_answer_pam_account(struct ssh *, int, struct sshbuf *);
int mm_answer_pam_init_ctx(struct ssh *, int, struct sshbuf *);
int mm_answer_pam_query(struct ssh *, int, struct sshbuf *);
int mm_answer_pam_respond(struct ssh *, int, struct sshbuf *);
int mm_answer_pam_free_ctx(struct ssh *, int, struct sshbuf *);
#endif
#ifdef KRB5
int mm_answer_krb5(struct ssh *, int, struct sshbuf *);
#endif
#ifdef GSSAPI
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 *);
#endif
/* local state for key verify */
static u_char *key_blob = NULL;
static size_t key_bloblen = 0;
static int key_blobtype = MM_NOKEY;
static struct sshauthopt *key_opts = NULL;
static char *hostbased_cuser = NULL;
static char *hostbased_chost = NULL;
static const char *auth_method = "unknown";
static const char *auth_submethod = NULL;
static u_int session_id2_len = 0;
static u_char *session_id2 = NULL;
static pid_t monitor_child_pid;
struct mon_table {
enum monitor_reqtype type;
int flags;
int (*f)(struct ssh *, int, struct sshbuf *);
};
#define MON_ISAUTH 0x0004 /* Required for Authentication */
#define MON_AUTHDECIDE 0x0008 /* Decides Authentication */
#define MON_ONCE 0x0010 /* Disable after calling */
#define MON_ALOG 0x0020 /* Log auth attempt without authenticating */
#define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE)
#define MON_PERMIT 0x1000 /* Request is permitted */
static int monitor_read(struct ssh *, struct monitor *, struct mon_table *,
struct mon_table **);
static int monitor_read_log(struct monitor *);
struct mon_table mon_dispatch_proto20[] = {
#ifdef WITH_OPENSSL
{MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
#endif
{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},
{MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account},
{MONITOR_REQ_PAM_INIT_CTX, MON_ISAUTH, mm_answer_pam_init_ctx},
{MONITOR_REQ_PAM_QUERY, MON_ISAUTH, mm_answer_pam_query},
{MONITOR_REQ_PAM_RESPOND, MON_ISAUTH, mm_answer_pam_respond},
{MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx},
#endif
#ifdef BSD_AUTH
{MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
{MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond},
#endif
{MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
{MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify},
#ifdef KRB5
{MONITOR_REQ_KRB5, MON_ONCE|MON_AUTH, mm_answer_krb5},
#endif
#ifdef GSSAPI
{MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx},
{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},
#endif
{0, 0, NULL}
};
struct mon_table mon_dispatch_postauth20[] = {
#ifdef WITH_OPENSSL
{MONITOR_REQ_MODULI, 0, mm_answer_moduli},
#endif
{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;
/* 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++;
}
}
void
monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
{
struct mon_table *ent;
int authenticated = 0, partial = 0;
Authctxt *authctxt = ssh->authctxt;
debug3("preauth child monitor started");
if (pmonitor->m_recvfd >= 0)
close(pmonitor->m_recvfd);
if (pmonitor->m_log_sendfd >= 0)
close(pmonitor->m_log_sendfd);
pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1;
memset(authctxt, 0, sizeof(*authctxt));
ssh->authctxt = authctxt;
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);
/* The first few requests do not require asynchronous access */
while (!authenticated) {
partial = 0;
auth_method = "unknown";
auth_submethod = NULL;
auth2_authctxt_reset_info(authctxt);
authenticated = (monitor_read(ssh, pmonitor,
mon_dispatch, &ent) == 1);
/* Special handling for multiple required authentications */
if (options.num_auth_methods != 0) {
if (authenticated &&
!auth2_update_methods_lists(authctxt,
auth_method, auth_submethod)) {
debug3("%s: method %s: partial", __func__,
auth_method);
authenticated = 0;
partial = 1;
}
}
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(ssh, auth_method))
authenticated = 0;
#ifdef USE_PAM
/* PAM needs to perform account checks after auth */
if (options.use_pam && authenticated) {
struct sshbuf *m;
if ((m = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
mm_request_receive_expect(pmonitor->m_sendfd,
MONITOR_REQ_PAM_ACCOUNT, m);
authenticated = mm_answer_pam_account(ssh, pmonitor->m_sendfd, m);
sshbuf_free(m);
}
#endif
}
if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
auth_log(ssh, authenticated, partial,
auth_method, auth_submethod);
if (!partial && !authenticated) {
pfilter_notify(1);
authctxt->failures++;
}
if (authenticated || partial) {
auth2_update_session_info(authctxt,
auth_method, auth_submethod);
}
}
}
if (!authctxt->valid)
fatal("%s: authenticated invalid user", __func__);
if (strcmp(auth_method, "unknown") == 0)
fatal("%s: authentication method name unknown", __func__);
debug("%s: %s has been authenticated by privileged process",
__func__, authctxt->user);
ssh->authctxt = NULL;
ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
mm_get_keystate(ssh, pmonitor);
/* Drain any buffered messages from the child */
while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
;
if (pmonitor->m_recvfd >= 0)
close(pmonitor->m_recvfd);
if (pmonitor->m_log_sendfd >= 0)
close(pmonitor->m_log_sendfd);
pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
}
static void
monitor_set_child_handler(pid_t pid)
{
monitor_child_pid = pid;
}
static void
monitor_child_handler(int sig)
{
kill(monitor_child_pid, sig);
}
void
monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
{
close(pmonitor->m_recvfd);
pmonitor->m_recvfd = -1;
monitor_set_child_handler(pmonitor->m_pid);
ssh_signal(SIGHUP, &monitor_child_handler);
ssh_signal(SIGTERM, &monitor_child_handler);
ssh_signal(SIGINT, &monitor_child_handler);
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);
if (auth_opts->permit_pty_flag) {
monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1);
}
for (;;)
monitor_read(ssh, pmonitor, mon_dispatch, NULL);
}
static int
monitor_read_log(struct monitor *pmonitor)
{
struct sshbuf *logmsg;
u_int len, level;
char *msg;
u_char *p;
int r;
if ((logmsg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new", __func__);
/* Read length */
if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0)
fatal("%s: reserve: %s", __func__, ssh_err(r));
if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) {
if (errno == EPIPE) {
sshbuf_free(logmsg);
debug("%s: child log fd closed", __func__);
close(pmonitor->m_log_recvfd);
pmonitor->m_log_recvfd = -1;
return -1;
}
fatal("%s: log fd read: %s", __func__, strerror(errno));
}
if ((r = sshbuf_get_u32(logmsg, &len)) != 0)
fatal("%s: get len: %s", __func__, ssh_err(r));
if (len <= 4 || len > 8192)
fatal("%s: invalid log message length %u", __func__, len);
/* Read severity, message */
sshbuf_reset(logmsg);
if ((r = sshbuf_reserve(logmsg, len, &p)) != 0)
fatal("%s: reserve: %s", __func__, ssh_err(r));
if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len)
fatal("%s: log fd read: %s", __func__, strerror(errno));
if ((r = sshbuf_get_u32(logmsg, &level)) != 0 ||
(r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0)
fatal("%s: decode: %s", __func__, ssh_err(r));
/* Log it */
if (log_level_name(level) == NULL)
fatal("%s: invalid log level %u (corrupted message?)",
__func__, level);
do_log2(level, "%s [preauth]", msg);
sshbuf_free(logmsg);
free(msg);
return 0;
}
static int
monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent,
struct mon_table **pent)
{
struct sshbuf *m;
int r, ret;
u_char type;
struct pollfd pfd[2];
for (;;) {
memset(&pfd, 0, sizeof(pfd));
pfd[0].fd = pmonitor->m_sendfd;
pfd[0].events = POLLIN;
pfd[1].fd = pmonitor->m_log_recvfd;
pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN;
if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) {
if (errno == EINTR || errno == EAGAIN)
continue;
fatal("%s: poll: %s", __func__, strerror(errno));
}
if (pfd[1].revents) {
/*
* Drain all log messages before processing next
* monitor request.
*/
monitor_read_log(pmonitor);
continue;
}
if (pfd[0].revents)
break; /* Continues below */
}
if ((m = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new", __func__);
mm_request_receive(pmonitor->m_sendfd, m);
if ((r = sshbuf_get_u8(m, &type)) != 0)
fatal("%s: decode: %s", __func__, ssh_err(r));
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)(ssh, pmonitor->m_sendfd, m);
sshbuf_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(const u_char *blob, u_int bloblen)
{
/* make sure key is allowed */
if (key_blob == NULL || key_bloblen != bloblen ||
timingsafe_bcmp(key_blob, blob, key_bloblen))
return (0);
return (1);
}
static void
monitor_reset_key_state(void)
{
/* reset state */
free(key_blob);
free(hostbased_cuser);
free(hostbased_chost);
sshauthopt_free(key_opts);
key_blob = NULL;
key_bloblen = 0;
key_blobtype = MM_NOKEY;
key_opts = NULL;
hostbased_cuser = NULL;
hostbased_chost = NULL;
}
#ifdef WITH_OPENSSL
int
mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m)
{
DH *dh;
const BIGNUM *dh_p, *dh_g;
int r;
u_int min, want, max;
if ((r = sshbuf_get_u32(m, &min)) != 0 ||
(r = sshbuf_get_u32(m, &want)) != 0 ||
(r = sshbuf_get_u32(m, &max)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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);
sshbuf_reset(m);
dh = choose_dh(min, want, max);
if (dh == NULL) {
if ((r = sshbuf_put_u8(m, 0)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
return (0);
} else {
/* Send first bignum */
DH_get0_pqg(dh, &dh_p, NULL, &dh_g);
if ((r = sshbuf_put_u8(m, 1)) != 0 ||
(r = sshbuf_put_bignum2(m, dh_p)) != 0 ||
(r = sshbuf_put_bignum2(m, dh_g)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
DH_free(dh);
}
mm_request_send(sock, MONITOR_ANS_MODULI, m);
return (0);
}
#endif
int
mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m)
{
extern int auth_sock; /* XXX move to state struct? */
struct sshkey *key;
struct sshbuf *sigbuf = NULL;
u_char *p = NULL, *signature = NULL;
char *alg = NULL;
size_t datlen, siglen, alglen;
int r, is_proof = 0;
u_int keyid, compat;
const char proof_req[] = "hostkeys-prove-00@openssh.com";
debug3("%s", __func__);
if ((r = sshbuf_get_u32(m, &keyid)) != 0 ||
(r = sshbuf_get_string(m, &p, &datlen)) != 0 ||
(r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 ||
(r = sshbuf_get_u32(m, &compat)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (keyid > INT_MAX)
fatal("%s: invalid key ID", __func__);
/*
* Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes),
* SHA384 (48 bytes) and SHA512 (64 bytes).
*
* Otherwise, verify the signature request is for a hostkey
* proof.
*
* XXX perform similar check for KEX signature requests too?
* it's not trivial, since what is signed is the hash, rather
* than the full kex structure...
*/
if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) {
/*
* Construct expected hostkey proof and compare it to what
* the client sent us.
*/
if (session_id2_len == 0) /* hostkeys is never first */
fatal("%s: bad data length: %zu", __func__, datlen);
if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL)
fatal("%s: no hostkey for index %d", __func__, keyid);
if ((sigbuf = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new", __func__);
if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 ||
(r = sshbuf_put_string(sigbuf, session_id2,
session_id2_len)) != 0 ||
(r = sshkey_puts(key, sigbuf)) != 0)
fatal("%s: couldn't prepare private key "
"proof buffer: %s", __func__, ssh_err(r));
if (datlen != sshbuf_len(sigbuf) ||
memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0)
fatal("%s: bad data length: %zu, hostkey proof len %zu",
__func__, datlen, sshbuf_len(sigbuf));
sshbuf_free(sigbuf);
is_proof = 1;
}
/* 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) {
if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg,
options.sk_provider, NULL, compat)) != 0)
fatal("%s: sshkey_sign failed: %s",
__func__, ssh_err(r));
} else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL &&
auth_sock > 0) {
if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen,
p, datlen, alg, compat)) != 0) {
fatal("%s: ssh_agent_sign failed: %s",
__func__, ssh_err(r));
}
} else
fatal("%s: no hostkey from index %d", __func__, keyid);
debug3("%s: %s signature %p(%zu)", __func__,
is_proof ? "hostkey proof" : "KEX", signature, siglen);
sshbuf_reset(m);
if ((r = sshbuf_put_string(m, signature, siglen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
free(alg);
free(p);
free(signature);
mm_request_send(sock, 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(struct ssh *ssh, int sock, struct sshbuf *m)
{
char *username;
struct passwd *pwent;
int r, allowed = 0;
u_int i;
Authctxt *authctxt = ssh->authctxt;
debug3("%s", __func__);
if (authctxt->attempt++ != 0)
fatal("%s: multiple attempts for getpwnam", __func__);
if ((r = sshbuf_get_cstring(m, &username, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
pwent = getpwnamallow(ssh, username);
authctxt->user = xstrdup(username);
setproctitle("%s [priv]", pwent ? username : "unknown");
free(username);
sshbuf_reset(m);
if (pwent == NULL) {
if ((r = sshbuf_put_u8(m, 0)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
authctxt->pw = fakepw();
goto out;
}
allowed = 1;
authctxt->pw = pwent;
authctxt->valid = 1;
/* XXX don't sent pwent to unpriv; send fake class/dir/shell too */
if ((r = sshbuf_put_u8(m, 1)) != 0 ||
(r = sshbuf_put_string(m, pwent, sizeof(*pwent))) != 0 ||
(r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 ||
(r = sshbuf_put_cstring(m, "*")) != 0 ||
(r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 ||
(r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 ||
(r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 ||
(r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
out:
ssh_packet_set_log_preamble(ssh, "%suser %s",
authctxt->valid ? "authenticating" : "invalid ", authctxt->user);
if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
#define M_CP_STROPT(x) do { \
if (options.x != NULL) { \
if ((r = sshbuf_put_cstring(m, options.x)) != 0) \
fatal("%s: buffer error: %s", \
__func__, ssh_err(r)); \
} \
} while (0)
#define M_CP_STRARRAYOPT(x, nx) do { \
for (i = 0; i < options.nx; i++) { \
if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \
fatal("%s: buffer error: %s", \
__func__, ssh_err(r)); \
} \
} while (0)
/* See comment in servconf.h */
COPY_MATCH_STRING_OPTS();
#undef M_CP_STROPT
#undef M_CP_STRARRAYOPT
/* Create valid auth method lists */
if (auth2_setup_methods_lists(authctxt) != 0) {
/*
* The monitor will continue long enough to let the child
* run to it's packet_disconnect(), but it must not allow any
* authentication to succeed.
*/
debug("%s: no valid authentication method lists", __func__);
}
debug3("%s: sending MONITOR_ANS_PWNAM: %d", __func__, allowed);
mm_request_send(sock, MONITOR_ANS_PWNAM, m);
/* 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
if (options.use_pam)
monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
#endif
return (0);
}
int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m)
{
char *banner;
int r;
sshbuf_reset(m);
banner = auth2_read_banner();
if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);
free(banner);
return (0);
}
int
mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m)
{
int r;
Authctxt *authctxt = ssh->authctxt;
monitor_permit_authentications(1);
if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 ||
(r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
debug3("%s: service=%s, style=%s",
__func__, authctxt->service, authctxt->style);
if (strlen(authctxt->style) == 0) {
free(authctxt->style);
authctxt->style = NULL;
}
return (0);
}
int
mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m)
{
static int call_count;
char *passwd;
int r, authenticated;
size_t plen;
if (!options.password_authentication)
fatal("%s: password authentication not enabled", __func__);
if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/* Only authenticate if the context is valid */
authenticated = options.password_authentication &&
auth_password(ssh, passwd);
freezero(passwd, plen);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, authenticated)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
debug3("%s: sending result %d", __func__, authenticated);
mm_request_send(sock, 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(struct ssh *ssh, int sock, struct sshbuf *m)
{
char *name, *infotxt;
u_int numprompts, *echo_on, success;
char **prompts;
int r;
if (!options.kbd_interactive_authentication)
fatal("%s: kbd-int authentication not enabled", __func__);
success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
&prompts, &echo_on) < 0 ? 0 : 1;
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, success)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (success) {
if ((r = sshbuf_put_cstring(m, prompts[0])) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
debug3("%s: sending challenge success: %u", __func__, success);
mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m);
if (success) {
free(name);
free(infotxt);
free(prompts);
free(echo_on);
}
return (0);
}
int
mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m)
{
char *response;
int r, authok;
if (!options.kbd_interactive_authentication)
fatal("%s: kbd-int authentication not enabled", __func__);
if (authctxt->as == NULL)
fatal("%s: no bsd auth session", __func__);
if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
authok = options.challenge_response_authentication &&
auth_userresponse(authctxt->as, response, 0);
authctxt->as = NULL;
debug3("%s: <%s> = <%d>", __func__, response, authok);
free(response);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, authok)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
debug3("%s: sending authenticated: %d", __func__, authok);
mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
auth_method = "keyboard-interactive";
auth_submethod = "bsdauth";
return (authok != 0);
}
#endif
#ifdef SKEY
int
mm_answer_skeyquery(int sock, struct sshbuf *m)
{
struct skey skey;
char challenge[1024];
u_int success;
success = skeychallenge(&skey, authctxt->user, challenge,
sizeof(challenge)) < 0 ? 0 : 1;
sshbuf_reset(m);
sshbuf_put_int(m, success);
if (success)
sshbuf_put_cstring(m, challenge);
debug3("%s: sending challenge success: %u", __func__, success);
mm_request_send(sock, MONITOR_ANS_SKEYQUERY, m);
return (0);
}
int
mm_answer_skeyrespond(int sock, struct sshbuf *m)
{
char *response;
int authok;
int r;
if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
authok = (options.challenge_response_authentication &&
authctxt->valid &&
skey_haskey(authctxt->pw->pw_name) == 0 &&
skey_passcheck(authctxt->pw->pw_name, response) != -1);
free(response);
sshbuf_reset(m);
sshbuf_put_int(m, authok);
debug3("%s: sending authenticated: %d", __func__, authok);
mm_request_send(sock, MONITOR_ANS_SKEYRESPOND, m);
auth_method = "skey";
auth_submethod = "bsdauth";
return (authok != 0);
}
#endif
#ifdef USE_PAM
int
mm_answer_pam_start(struct ssh *ssh, int sock, struct sshbuf *m)
{
if (!options.use_pam)
fatal("UsePAM not set, but ended up in %s anyway", __func__);
start_pam(ssh);
monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1);
return (0);
}
int
mm_answer_pam_account(struct ssh *ssh, int sock, struct sshbuf *m)
{
u_int ret;
if (!options.use_pam)
fatal("UsePAM not set, but ended up in %s anyway", __func__);
ret = do_pam_account();
sshbuf_put_u32(m, ret);
sshbuf_put_string(m, sshbuf_ptr(loginmsg), sshbuf_len(loginmsg));
mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m);
return (ret);
}
static void *sshpam_ctxt, *sshpam_authok;
extern KbdintDevice sshpam_device;
int
mm_answer_pam_init_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
{
debug3("%s", __func__);
sshpam_ctxt = (sshpam_device.init_ctx)(ssh->authctxt);
sshpam_authok = NULL;
sshbuf_reset(m);
if (sshpam_ctxt != NULL) {
monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1);
sshbuf_put_u32(m, 1);
} else {
sshbuf_put_u32(m, 0);
}
mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m);
return (0);
}
int
mm_answer_pam_query(struct ssh *ssh, int sock, struct sshbuf *m)
{
char *name, *info, **prompts;
u_int i, num, *echo_on;
int ret;
debug3("%s", __func__);
sshpam_authok = NULL;
ret = (sshpam_device.query)(sshpam_ctxt, &name, &info, &num, &prompts, &echo_on);
if (ret == 0 && num == 0)
sshpam_authok = sshpam_ctxt;
if (num > 1 || name == NULL || info == NULL)
ret = -1;
sshbuf_reset(m);
sshbuf_put_u32(m, ret);
sshbuf_put_cstring(m, name);
free(name);
sshbuf_put_cstring(m, info);
free(info);
sshbuf_put_u32(m, num);
for (i = 0; i < num; ++i) {
sshbuf_put_cstring(m, prompts[i]);
free(prompts[i]);
sshbuf_put_u32(m, echo_on[i]);
}
if (prompts != NULL)
free(prompts);
if (echo_on != NULL)
free(echo_on);
auth_method = "keyboard-interactive/pam";
mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m);
return (0);
}
int
mm_answer_pam_respond(struct ssh *ssh, int sock, struct sshbuf *m)
{
char **resp;
u_int i, num;
int ret, r;
debug3("%s", __func__);
sshpam_authok = NULL;
if ((r = sshbuf_get_u32(m, &num)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (num > 0) {
resp = xmalloc(num * sizeof(char *));
for (i = 0; i < num; ++i)
if ((r = sshbuf_get_cstring(m, &resp[i], NULL)) != 0)
fatal("%s: buffer error: %s", __func__,
ssh_err(r));
ret = (sshpam_device.respond)(sshpam_ctxt, num, resp);
for (i = 0; i < num; ++i)
free(resp[i]);
free(resp);
} else {
ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL);
}
sshbuf_reset(m);
sshbuf_put_u32(m, ret);
mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m);
auth_method = "keyboard-interactive/pam";
if (ret == 0)
sshpam_authok = sshpam_ctxt;
return (0);
}
int
mm_answer_pam_free_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
{
int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt;
debug3("%s", __func__);
(sshpam_device.free_ctx)(sshpam_ctxt);
sshpam_ctxt = sshpam_authok = NULL;
sshbuf_reset(m);
mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m);
auth_method = "keyboard-interactive/pam";
return r;
}
#endif
/*
* Check that the key type appears in the supplied pattern list, ignoring
* mismatches in the signature algorithm. (Signature algorithm checks are
* performed in the unprivileged authentication code).
* Returns 1 on success, 0 otherwise.
*/
static int
key_base_type_match(const char *method, const struct sshkey *key,
const char *list)
{
char *s, *l, *ol = xstrdup(list);
int found = 0;
l = ol;
for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) {
if (sshkey_type_from_name(s) == key->type) {
found = 1;
break;
}
}
if (!found) {
error("%s key type %s is not in permitted list %s", method,
sshkey_ssh_name(key), list);
}
free(ol);
return found;
}
int
mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m)
{
struct sshkey *key = NULL;
char *cuser, *chost;
u_int pubkey_auth_attempt;
enum mm_keytype type = 0;
int r, allowed = 0;
struct sshauthopt *opts = NULL;
Authctxt *authctxt = ssh->authctxt;
debug3("%s entering", __func__);
if ((r = sshbuf_get_u32(m, &type)) != 0 ||
(r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 ||
(r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
(r = sshkey_froms(m, &key)) != 0 ||
(r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
debug3("%s: key_from_blob: %p", __func__, key);
if (key != NULL && authctxt->valid) {
/* These should not make it past the privsep child */
if (sshkey_type_plain(key->type) == KEY_RSA &&
(datafellows & SSH_BUG_RSASIGMD5) != 0)
fatal("%s: passed a SSH_BUG_RSASIGMD5 key", __func__);
switch (type) {
case MM_USERKEY:
auth_method = "publickey";
if (!options.pubkey_authentication)
break;
if (auth2_key_already_used(authctxt, key))
break;
if (!key_base_type_match(auth_method, key,
options.pubkey_key_types))
break;
allowed = user_key_allowed(ssh, authctxt->pw, key,
pubkey_auth_attempt, &opts);
break;
case MM_HOSTKEY:
auth_method = "hostbased";
if (!options.hostbased_authentication)
break;
if (auth2_key_already_used(authctxt, key))
break;
if (!key_base_type_match(auth_method, key,
options.hostbased_key_types))
break;
allowed = hostbased_key_allowed(ssh, authctxt->pw,
cuser, chost, key);
auth2_record_info(authctxt,
"client user \"%.100s\", client host \"%.100s\"",
cuser, chost);
break;
default:
fatal("%s: unknown key type %d", __func__, type);
break;
}
}
debug3("%s: %s authentication%s: %s key is %s", __func__,
auth_method, pubkey_auth_attempt ? "" : " test",
(key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key),
allowed ? "allowed" : "not allowed");
auth2_record_key(authctxt, 0, key);
/* clear temporarily storage (used by verify) */
monitor_reset_key_state();
if (allowed) {
/* Save temporarily for comparison in verify */
if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
key_blobtype = type;
key_opts = opts;
hostbased_cuser = cuser;
hostbased_chost = chost;
} else {
/* Log failed attempt */
auth_log(ssh, 0, 0, auth_method, NULL);
pfilter_notify(1);
free(cuser);
free(chost);
}
sshkey_free(key);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, allowed)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0)
fatal("%s: sshauthopt_serialise: %s", __func__, ssh_err(r));
mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);
if (!allowed)
sshauthopt_free(opts);
return (0);
}
static int
monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen)
{
struct sshbuf *b;
const u_char *p;
char *userstyle, *cp;
size_t len;
u_char type;
int r, fail = 0;
Authctxt *authctxt = ssh->authctxt;
if ((b = sshbuf_from(data, datalen)) == NULL)
fatal("%s: sshbuf_from", __func__);
if (datafellows & SSH_OLD_SESSIONID) {
p = sshbuf_ptr(b);
len = sshbuf_len(b);
if ((session_id2 == NULL) ||
(len < session_id2_len) ||
(timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
fail++;
if ((r = sshbuf_consume(b, session_id2_len)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
} else {
if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if ((session_id2 == NULL) ||
(len != session_id2_len) ||
(timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
fail++;
}
if ((r = sshbuf_get_u8(b, &type)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (type != SSH2_MSG_USERAUTH_REQUEST)
fail++;
if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
xasprintf(&userstyle, "%s%s%s", authctxt->user,
authctxt->style ? ":" : "",
authctxt->style ? authctxt->style : "");
if (strcmp(userstyle, cp) != 0) {
logit("wrong user name passed to monitor: "
"expected %s != %.100s", userstyle, cp);
fail++;
}
free(userstyle);
free(cp);
if ((r = sshbuf_skip_string(b)) != 0 || /* service */
(r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (strcmp("publickey", cp) != 0)
fail++;
free(cp);
if ((r = sshbuf_get_u8(b, &type)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (type == 0)
fail++;
if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */
(r = sshbuf_skip_string(b)) != 0) /* pkblob */
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (sshbuf_len(b) != 0)
fail++;
sshbuf_free(b);
return (fail == 0);
}
static int
monitor_valid_hostbasedblob(struct ssh *ssh, const u_char *data, u_int datalen,
const char *cuser, const char *chost)
{
struct sshbuf *b;
const u_char *p;
char *cp, *userstyle;
size_t len;
int r, fail = 0;
u_char type;
Authctxt *authctxt = ssh->authctxt;
if ((b = sshbuf_from(data, datalen)) == NULL)
fatal("%s: sshbuf_new", __func__);
if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if ((session_id2 == NULL) ||
(len != session_id2_len) ||
(timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
fail++;
if ((r = sshbuf_get_u8(b, &type)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (type != SSH2_MSG_USERAUTH_REQUEST)
fail++;
if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
xasprintf(&userstyle, "%s%s%s", authctxt->user,
authctxt->style ? ":" : "",
authctxt->style ? authctxt->style : "");
if (strcmp(userstyle, cp) != 0) {
logit("wrong user name passed to monitor: "
"expected %s != %.100s", userstyle, cp);
fail++;
}
free(userstyle);
free(cp);
if ((r = sshbuf_skip_string(b)) != 0 || /* service */
(r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (strcmp(cp, "hostbased") != 0)
fail++;
free(cp);
if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */
(r = sshbuf_skip_string(b)) != 0) /* pkblob */
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/* verify client host, strip trailing dot if necessary */
if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (((len = strlen(cp)) > 0) && cp[len - 1] == '.')
cp[len - 1] = '\0';
if (strcmp(cp, chost) != 0)
fail++;
free(cp);
/* verify client user */
if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (strcmp(cp, cuser) != 0)
fail++;
free(cp);
if (sshbuf_len(b) != 0)
fail++;
sshbuf_free(b);
return (fail == 0);
}
int
mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m)
{
struct sshkey *key;
const u_char *signature, *data, *blob;
char *sigalg = NULL, *fp = NULL;
size_t signaturelen, datalen, bloblen;
int r, ret, req_presence = 0, req_verify = 0, valid_data = 0;
int encoded_ret;
struct sshkey_sig_details *sig_details = NULL;
Authctxt *authctxt = ssh->authctxt;
if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 ||
(r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 ||
(r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 ||
(r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (hostbased_cuser == NULL || hostbased_chost == NULL ||
!monitor_allowed_key(blob, bloblen))
fatal("%s: bad key, not previously allowed", __func__);
/* Empty signature algorithm means NULL. */
if (*sigalg == '\0') {
free(sigalg);
sigalg = NULL;
}
/* XXX use sshkey_froms here; need to change key_blob, etc. */
if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
fatal("%s: bad public key blob: %s", __func__, ssh_err(r));
switch (key_blobtype) {
case MM_USERKEY:
valid_data = monitor_valid_userblob(ssh, data, datalen);
auth_method = "publickey";
break;
case MM_HOSTKEY:
valid_data = monitor_valid_hostbasedblob(ssh, data, datalen,
hostbased_cuser, hostbased_chost);
auth_method = "hostbased";
break;
default:
valid_data = 0;
break;
}
if (!valid_data)
fatal("%s: bad signature data blob", __func__);
if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL)
fatal("%s: sshkey_fingerprint failed", __func__);
ret = sshkey_verify(key, signature, signaturelen, data, datalen,
sigalg, ssh->compat, &sig_details);
debug3("%s: %s %p signature %s%s%s", __func__, auth_method, key,
(ret == 0) ? "verified" : "unverified",
(ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : "");
if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) {
req_presence = (options.pubkey_auth_options &
PUBKEYAUTH_TOUCH_REQUIRED) ||
!key_opts->no_require_user_presence;
if (req_presence &&
(sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) {
error("public key %s %s signature for %s%s from %.128s "
"port %d rejected: user presence "
"(authenticator touch) requirement not met ",
sshkey_type(key), fp,
authctxt->valid ? "" : "invalid user ",
authctxt->user, ssh_remote_ipaddr(ssh),
ssh_remote_port(ssh));
ret = SSH_ERR_SIGNATURE_INVALID;
}
req_verify = (options.pubkey_auth_options &
PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify;
if (req_verify &&
(sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) {
error("public key %s %s signature for %s%s from %.128s "
"port %d rejected: user verification requirement "
"not met ", sshkey_type(key), fp,
authctxt->valid ? "" : "invalid user ",
authctxt->user, ssh_remote_ipaddr(ssh),
ssh_remote_port(ssh));
ret = SSH_ERR_SIGNATURE_INVALID;
}
}
auth2_record_key(authctxt, ret == 0, key);
if (key_blobtype == MM_USERKEY)
auth_activate_options(ssh, key_opts);
monitor_reset_key_state();
sshbuf_reset(m);
/* encode ret != 0 as positive integer, since we're sending u32 */
encoded_ret = (ret != 0);
if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 ||
(r = sshbuf_put_u8(m, sig_details != NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if (sig_details != NULL) {
if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 ||
(r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
sshkey_sig_details_free(sig_details);
mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
free(sigalg);
free(fp);
sshkey_free(key);
return ret == 0;
}
static void
mm_record_login(struct ssh *ssh, 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 (ssh_packet_connection_is_on_socket(ssh)) {
if (getpeername(ssh_packet_get_connection_in(ssh),
(struct sockaddr *)&from, &fromlen) == -1) {
debug("getpeername: %.100s", strerror(errno));
cleanup_exit(254);
}
}
/* 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,
session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns),
(struct sockaddr *)&from, fromlen);
}
static void
mm_session_close(Session *s)
{
debug3("%s: session %d pid %ld", __func__, s->self, (long)s->pid);
if (s->ttyfd != -1) {
debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ptyfd);
session_pty_cleanup2(s);
}
session_unused(s->self);
}
int
mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m)
{
extern struct monitor *pmonitor;
Session *s;
int r, res, fd0;
Authctxt *authctxt = ssh->authctxt;
debug3("%s entering", __func__);
sshbuf_reset(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;
pty_setowner(authctxt->pw, s->tty);
if ((r = sshbuf_put_u32(m, 1)) != 0 ||
(r = sshbuf_put_cstring(m, s->tty)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/* We need to trick ttyslot */
if (dup2(s->ttyfd, 0) == -1)
fatal("%s: dup2", __func__);
mm_record_login(ssh, s, authctxt->pw);
/* Now we can close the file descriptor again */
close(0);
/* send messages generated by record_login */
if ((r = sshbuf_put_stringb(m, loginmsg)) != 0)
fatal("%s: put login message: %s", __func__, ssh_err(r));
sshbuf_reset(loginmsg);
mm_request_send(sock, MONITOR_ANS_PTY, m);
if (mm_send_fd(sock, s->ptyfd) == -1 ||
mm_send_fd(sock, s->ttyfd) == -1)
fatal("%s: send fds failed", __func__);
/* make sure nothing uses fd 0 */
if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1)
fatal("%s: open(/dev/null): %s", __func__, strerror(errno));
if (fd0 != 0)
error("%s: fd0 %d != 0", __func__, fd0);
/* slave side of pty 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);
if ((r = sshbuf_put_u32(m, 0)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(sock, MONITOR_ANS_PTY, m);
return (0);
}
int
mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m)
{
Session *s;
char *tty;
int r;
debug3("%s entering", __func__);
if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
if ((s = session_by_tty(tty)) != NULL)
mm_session_close(s);
sshbuf_reset(m);
free(tty);
return (0);
}
#ifdef KRB5
int
mm_answer_krb5(struct ssh *ssh, int xsocket, struct sshbuf *m)
{
krb5_data tkt, reply;
char *client_user;
unsigned char *data;
size_t len;
int r;
int success;
Authctxt *authctxt = ssh->authctxt;
/* use temporary var to avoid size issues on 64bit arch */
if ((r = sshbuf_get_string(m, &data, &len)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
tkt.data = data;
tkt.length = len;
success = options.kerberos_authentication &&
authctxt->valid &&
auth_krb5(ssh, &tkt, &client_user, &reply);
if (tkt.length)
free(tkt.data);
sshbuf_reset(m);
sshbuf_put_u32(m, success);
if (success) {
sshbuf_put_cstring(m, client_user);
sshbuf_put_string(m, reply.data, reply.length);
if (client_user)
free(client_user);
if (reply.length)
free(reply.data);
}
mm_request_send(xsocket, MONITOR_ANS_KRB5, m);
auth_method = "kerberos";
return success;
}
#endif
int
mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req)
{
extern struct monitor *pmonitor;
int res, status;
debug3("%s: tearing down sessions", __func__);
/* The child is terminating */
session_destroy_all(ssh, &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_clear_keystate(struct ssh *ssh, struct monitor *pmonitor)
{
ssh_clear_newkeys(ssh, MODE_IN);
ssh_clear_newkeys(ssh, MODE_OUT);
sshbuf_free(child_state);
child_state = NULL;
}
void
monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor)
{
struct kex *kex;
int r;
debug3("%s: packet_set_state", __func__);
if ((r = ssh_packet_set_state(ssh, child_state)) != 0)
fatal("%s: packet_set_state: %s", __func__, ssh_err(r));
sshbuf_free(child_state);
child_state = NULL;
if ((kex = ssh->kex) != NULL) {
/* XXX set callbacks */
#ifdef WITH_OPENSSL
kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
#endif
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;
kex->load_host_private_key=&get_hostkey_private_by_type;
kex->host_key_index=&get_hostkey_index;
kex->sign = sshd_hostkey_sign;
}
}
/* This function requires careful sanity checking */
void
mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor)
{
debug3("%s: Waiting for new keys", __func__);
if ((child_state = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT,
child_state);
debug3("%s: GOT new keys", __func__);
}
/* XXX */
#define FD_CLOSEONEXEC(x) do { \
if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \
fatal("fcntl(%d, F_SETFD)", x); \
} while (0)
static void
monitor_openfds(struct monitor *mon, int do_logfds)
{
int pair[2];
#ifdef SO_ZEROIZE
int on = 1;
#endif
if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
fatal("%s: socketpair: %s", __func__, strerror(errno));
#ifdef SO_ZEROIZE
if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno));
if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno));
#endif
FD_CLOSEONEXEC(pair[0]);
FD_CLOSEONEXEC(pair[1]);
mon->m_recvfd = pair[0];
mon->m_sendfd = pair[1];
if (do_logfds) {
if (pipe(pair) == -1)
fatal("%s: pipe: %s", __func__, strerror(errno));
FD_CLOSEONEXEC(pair[0]);
FD_CLOSEONEXEC(pair[1]);
mon->m_log_recvfd = pair[0];
mon->m_log_sendfd = pair[1];
} else
mon->m_log_recvfd = mon->m_log_sendfd = -1;
}
#define MM_MEMSIZE 65536
struct monitor *
monitor_init(void)
{
struct monitor *mon;
mon = xcalloc(1, sizeof(*mon));
monitor_openfds(mon, 1);
return mon;
}
void
monitor_reinit(struct monitor *mon)
{
monitor_openfds(mon, 0);
}
#ifdef GSSAPI
int
mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
{
gss_OID_desc goid;
OM_uint32 major;
size_t len;
u_char *p;
int r;
if (!options.gss_authentication)
fatal("%s: GSSAPI authentication not enabled", __func__);
if ((r = sshbuf_get_string(m, &p, &len)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
goid.elements = p;
goid.length = len;
major = ssh_gssapi_server_ctx(&gsscontext, &goid);
free(goid.elements);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, major)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(sock, MONITOR_ANS_GSSSETUP, m);
/* Now we have a context, enable the step */
monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1);
return (0);
}
int
mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
{
gss_buffer_desc in;
gss_buffer_desc out = GSS_C_EMPTY_BUFFER;
OM_uint32 major, minor;
OM_uint32 flags = 0; /* GSI needs this */
int r;
if (!options.gss_authentication)
fatal("%s: GSSAPI authentication not enabled", __func__);
if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags);
free(in.value);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, major)) != 0 ||
(r = sshbuf_put_string(m, out.value, out.length)) != 0 ||
(r = sshbuf_put_u32(m, flags)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(sock, MONITOR_ANS_GSSSTEP, m);
gss_release_buffer(&minor, &out);
if (major == GSS_S_COMPLETE) {
monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
}
return (0);
}
int
mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
{
gss_buffer_desc gssbuf, mic;
OM_uint32 ret;
int r;
if (!options.gss_authentication)
fatal("%s: GSSAPI authentication not enabled", __func__);
if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
(r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);
free(gssbuf.value);
free(mic.value);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, ret)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m);
if (!GSS_ERROR(ret))
monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
return (0);
}
int
mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
{
int r, authenticated;
const char *displayname;
Authctxt *authctxt = ssh->authctxt;
if (!options.gss_authentication)
fatal("%s: GSSAPI authentication not enabled", __func__);
authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
sshbuf_reset(m);
if ((r = sshbuf_put_u32(m, authenticated)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
debug3("%s: sending result %d", __func__, authenticated);
mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
auth_method = "gssapi-with-mic";
if ((displayname = ssh_gssapi_displayname()) != NULL)
auth2_record_info(authctxt, "%s", displayname);
/* Monitor loop will terminate if authenticated */
return (authenticated);
}
#endif /* GSSAPI */
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