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monitor.c
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monitor.c
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/* $OpenBSD: monitor.c,v 1.150 2015/06/22 23:42:16 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"
#include <sys/types.h>
#include <sys/socket.h>
#include "openbsd-compat/sys-tree.h"
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#include <pwd.h>
#include <signal.h>
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <stdio.h>
#include <unistd.h>
#ifdef HAVE_POLL_H
#include <poll.h>
#else
# ifdef HAVE_SYS_POLL_H
# include <sys/poll.h>
# endif
#endif
#ifdef SKEY
#include <skey.h>
#endif
#ifdef WITH_OPENSSL
#include <openssl/dh.h>
#endif
#include "openbsd-compat/sys-queue.h"
#include "atomicio.h"
#include "xmalloc.h"
#include "ssh.h"
#include "key.h"
#include "buffer.h"
#include "hostfile.h"
#include "auth.h"
#include "cipher.h"
#include "kex.h"
#include "dh.h"
#ifdef TARGET_OS_MAC /* XXX Broken krb5 headers on Mac */
#undef TARGET_OS_MAC
#include "zlib.h"
#define TARGET_OS_MAC 1
#else
#include "zlib.h"
#endif
#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"
#include "monitor_mm.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "monitor_fdpass.h"
#include "compat.h"
#include "ssh2.h"
#include "roaming.h"
#include "authfd.h"
#include "match.h"
#include "ssherr.h"
#ifdef GSSAPI
static Gssctxt *gsscontext = NULL;
#endif
/* Imports */
extern ServerOptions options;
extern u_int utmp_len;
extern u_char session_id[];
extern Buffer auth_debug;
extern int auth_debug_init;
extern Buffer loginmsg;
/* State exported from the child */
static struct sshbuf *child_state;
/* Functions on the monitor 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 *);
int mm_answer_pam_account(int, Buffer *);
int mm_answer_pam_init_ctx(int, Buffer *);
int mm_answer_pam_query(int, Buffer *);
int mm_answer_pam_respond(int, Buffer *);
int mm_answer_pam_free_ctx(int, Buffer *);
#endif
#ifdef GSSAPI
int mm_answer_gss_setup_ctx(int, Buffer *);
int mm_answer_gss_accept_ctx(int, Buffer *);
int mm_answer_gss_userok(int, Buffer *);
int mm_answer_gss_checkmic(int, Buffer *);
#endif
#ifdef SSH_AUDIT_EVENTS
int mm_answer_audit_event(int, Buffer *);
int mm_answer_audit_command(int, Buffer *);
#endif
static int monitor_read_log(struct monitor *);
static Authctxt *authctxt;
#ifdef WITH_SSH1
static BIGNUM *ssh1_challenge = NULL; /* used for ssh1 rsa auth */
#endif
/* 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 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)(int, Buffer *);
};
#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 */
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 SSH_AUDIT_EVENTS
{MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
#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},
#ifdef GSSAPI
{MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx},
{MONITOR_REQ_GSSSTEP, MON_ISAUTH, mm_answer_gss_accept_ctx},
{MONITOR_REQ_GSSUSEROK, MON_AUTH, mm_answer_gss_userok},
{MONITOR_REQ_GSSCHECKMIC, MON_ISAUTH, 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},
#ifdef SSH_AUDIT_EVENTS
{MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
{MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command},
#endif
{0, 0, NULL}
};
struct mon_table mon_dispatch_proto15[] = {
#ifdef WITH_SSH1
{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|MON_ALOG, mm_answer_rsa_keyallowed},
{MONITOR_REQ_KEYALLOWED, MON_ISAUTH|MON_ALOG, 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},
{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 SSH_AUDIT_EVENTS
{MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
#endif
#endif /* WITH_SSH1 */
{0, 0, NULL}
};
struct mon_table mon_dispatch_postauth15[] = {
#ifdef WITH_SSH1
{MONITOR_REQ_PTY, MON_ONCE, mm_answer_pty},
{MONITOR_REQ_PTYCLEANUP, MON_ONCE, mm_answer_pty_cleanup},
{MONITOR_REQ_TERM, 0, mm_answer_term},
#ifdef SSH_AUDIT_EVENTS
{MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
{MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT|MON_ONCE, mm_answer_audit_command},
#endif
#endif /* WITH_SSH1 */
{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(Authctxt *_authctxt, struct monitor *pmonitor)
{
struct mon_table *ent;
int authenticated = 0, partial = 0;
debug3("preauth child monitor started");
close(pmonitor->m_recvfd);
close(pmonitor->m_log_sendfd);
pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1;
authctxt = _authctxt;
memset(authctxt, 0, sizeof(*authctxt));
authctxt->loginmsg = &loginmsg;
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);
}
/* The first few requests do not require asynchronous access */
while (!authenticated) {
partial = 0;
auth_method = "unknown";
auth_submethod = NULL;
authenticated = (monitor_read(pmonitor, mon_dispatch, &ent) == 1);
/* Special handling for multiple required authentications */
if (options.num_auth_methods != 0) {
if (!compat20)
fatal("AuthenticationMethods is not supported"
"with SSH protocol 1");
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(auth_method))
authenticated = 0;
#ifdef USE_PAM
/* PAM needs to perform account checks after auth */
if (options.use_pam && authenticated) {
Buffer m;
buffer_init(&m);
mm_request_receive_expect(pmonitor->m_sendfd,
MONITOR_REQ_PAM_ACCOUNT, &m);
authenticated = mm_answer_pam_account(pmonitor->m_sendfd, &m);
buffer_free(&m);
}
#endif
}
if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
auth_log(authctxt, authenticated, partial,
auth_method, auth_submethod);
if (!partial && !authenticated)
authctxt->failures++;
}
}
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);
mm_get_keystate(pmonitor);
/* Drain any buffered messages from the child */
while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
;
close(pmonitor->m_sendfd);
close(pmonitor->m_log_recvfd);
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 monitor *pmonitor)
{
close(pmonitor->m_recvfd);
pmonitor->m_recvfd = -1;
monitor_set_child_handler(pmonitor->m_pid);
signal(SIGHUP, &monitor_child_handler);
signal(SIGTERM, &monitor_child_handler);
signal(SIGINT, &monitor_child_handler);
#ifdef SIGXFSZ
signal(SIGXFSZ, SIG_IGN);
#endif
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);
}
}
/* Allocation functions for zlib */
static 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_MAX / size)
fatal("%s: mm_zalloc(%u, %u)", __func__, ncount, size);
address = mm_malloc(mm, len);
return (address);
}
static void
mm_zfree(struct mm_master *mm, void *address)
{
mm_free(mm, address);
}
static int
monitor_read_log(struct monitor *pmonitor)
{
Buffer logmsg;
u_int len, level;
char *msg;
buffer_init(&logmsg);
/* Read length */
buffer_append_space(&logmsg, 4);
if (atomicio(read, pmonitor->m_log_recvfd,
buffer_ptr(&logmsg), buffer_len(&logmsg)) != buffer_len(&logmsg)) {
if (errno == EPIPE) {
buffer_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));
}
len = buffer_get_int(&logmsg);
if (len <= 4 || len > 8192)
fatal("%s: invalid log message length %u", __func__, len);
/* Read severity, message */
buffer_clear(&logmsg);
buffer_append_space(&logmsg, len);
if (atomicio(read, pmonitor->m_log_recvfd,
buffer_ptr(&logmsg), buffer_len(&logmsg)) != buffer_len(&logmsg))
fatal("%s: log fd read: %s", __func__, strerror(errno));
/* Log it */
level = buffer_get_int(&logmsg);
msg = buffer_get_string(&logmsg, NULL);
if (log_level_name(level) == NULL)
fatal("%s: invalid log level %u (corrupted message?)",
__func__, level);
do_log2(level, "%s [preauth]", msg);
buffer_free(&logmsg);
free(msg);
return 0;
}
int
monitor_read(struct monitor *pmonitor, struct mon_table *ent,
struct mon_table **pent)
{
Buffer m;
int 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 */
}
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 ||
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);
key_blob = NULL;
key_bloblen = 0;
key_blobtype = MM_NOKEY;
hostbased_cuser = NULL;
hostbased_chost = NULL;
}
#ifdef WITH_OPENSSL
int
mm_answer_moduli(int sock, 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(sock, MONITOR_ANS_MODULI, m);
return (0);
}
#endif
int
mm_answer_sign(int sock, Buffer *m)
{
struct ssh *ssh = active_state; /* XXX */
extern int auth_sock; /* XXX move to state struct? */
struct sshkey *key;
struct sshbuf *sigbuf;
u_char *p;
u_char *signature;
size_t datlen, siglen;
int r, keyid, is_proof = 0;
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)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
/*
* 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,
datafellows)) != 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, datafellows)) != 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 ? "KEX" : "hostkey proof", signature, siglen);
sshbuf_reset(m);
if ((r = sshbuf_put_string(m, signature, siglen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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(int sock, Buffer *m)
{
char *username;
struct passwd *pwent;
int allowed = 0;
u_int i;
debug3("%s", __func__);
if (authctxt->attempt++ != 0)
fatal("%s: multiple attempts for getpwnam", __func__);
username = buffer_get_string(m, NULL);
pwent = getpwnamallow(username);
authctxt->user = xstrdup(username);
setproctitle("%s [priv]", pwent ? username : "unknown");
free(username);
buffer_clear(m);
if (pwent == NULL) {
buffer_put_char(m, 0);
authctxt->pw = fakepw();
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, "*");
#ifdef HAVE_STRUCT_PASSWD_PW_GECOS
buffer_put_cstring(m, pwent->pw_gecos);
#endif
#ifdef HAVE_STRUCT_PASSWD_PW_CLASS
buffer_put_cstring(m, pwent->pw_class);
#endif
buffer_put_cstring(m, pwent->pw_dir);
buffer_put_cstring(m, pwent->pw_shell);
out:
buffer_put_string(m, &options, sizeof(options));
#define M_CP_STROPT(x) do { \
if (options.x != NULL) \
buffer_put_cstring(m, options.x); \
} while (0)
#define M_CP_STRARRAYOPT(x, nx) do { \
for (i = 0; i < options.nx; i++) \
buffer_put_cstring(m, options.x[i]); \
} 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 (compat20 && 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);
/* 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
if (options.use_pam)
monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
#endif
return (0);
}
int mm_answer_auth2_read_banner(int sock, Buffer *m)
{
char *banner;
buffer_clear(m);
banner = auth2_read_banner();
buffer_put_cstring(m, banner != NULL ? banner : "");
mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);
free(banner);
return (0);
}
int
mm_answer_authserv(int sock, 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) {
free(authctxt->style);
authctxt->style = NULL;
}
return (0);
}
int
mm_answer_authpassword(int sock, 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 &&
auth_password(authctxt, passwd);
explicit_bzero(passwd, strlen(passwd));
free(passwd);
buffer_clear(m);
buffer_put_int(m, authenticated);
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(int sock, Buffer *m)
{
char *name, *infotxt;
u_int numprompts;
u_int *echo_on;
char **prompts;
u_int success;
success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
&prompts, &echo_on) < 0 ? 0 : 1;
buffer_clear(m);
buffer_put_int(m, success);
if (success)
buffer_put_cstring(m, prompts[0]);
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(int sock, 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);
free(response);
buffer_clear(m);
buffer_put_int(m, authok);
debug3("%s: sending authenticated: %d", __func__, authok);
mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
if (compat20) {
auth_method = "keyboard-interactive";
auth_submethod = "bsdauth";
} else
auth_method = "bsdauth";
return (authok != 0);
}
#endif
#ifdef SKEY