vfs/procfs: Add kqueue support

[dragonfly.git] / crypto / openssh / monitor_wrap.c

/* $OpenBSD: monitor_wrap.c,v 1.136 2024/06/19 23:24:47 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/uio.h>
#include <sys/wait.h>

#include <errno.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#ifdef WITH_OPENSSL
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/evp.h>
#endif

#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
#include "ssh.h"
#ifdef WITH_OPENSSL
#include "dh.h"
#endif
#include "sshbuf.h"
#include "sshkey.h"
#include "cipher.h"
#include "kex.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
#include "packet.h"
#include "mac.h"
#include "log.h"
#include "auth-pam.h"
#include "monitor.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "atomicio.h"
#include "monitor_fdpass.h"
#include "misc.h"

#include "channels.h"
#include "session.h"
#include "servconf.h"
#include "monitor_wrap.h"
#include "srclimit.h"

#include "ssherr.h"

/* Imports */
extern struct monitor *pmonitor;
extern struct sshbuf *loginmsg;
extern ServerOptions options;

void
mm_log_handler(LogLevel level, int forced, const char *msg, void *ctx)
{
        struct sshbuf *log_msg;
        struct monitor *mon = (struct monitor *)ctx;
        int r;
        size_t len;

        if (mon->m_log_sendfd == -1)
                fatal_f("no log channel");

        if ((log_msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        if ((r = sshbuf_put_u32(log_msg, 0)) != 0 || /* length; filled below */
            (r = sshbuf_put_u32(log_msg, level)) != 0 ||
            (r = sshbuf_put_u32(log_msg, forced)) != 0 ||
            (r = sshbuf_put_cstring(log_msg, msg)) != 0)
                fatal_fr(r, "assemble");
        if ((len = sshbuf_len(log_msg)) < 4 || len > 0xffffffff)
                fatal_f("bad length %zu", len);
        POKE_U32(sshbuf_mutable_ptr(log_msg), len - 4);
        if (atomicio(vwrite, mon->m_log_sendfd,
            sshbuf_mutable_ptr(log_msg), len) != len)
                fatal_f("write: %s", strerror(errno));
        sshbuf_free(log_msg);
}

int
mm_is_monitor(void)
{
        /*
         * m_pid is only set in the privileged part, and
         * points to the unprivileged child.
         */
        return (pmonitor && pmonitor->m_pid > 0);
}

static void
mm_reap(void)
{
        int status = -1;

        if (!mm_is_monitor())
                return;
        while (waitpid(pmonitor->m_pid, &status, 0) == -1) {
                if (errno == EINTR)
                        continue;
                pmonitor->m_pid = -1;
                fatal_f("waitpid: %s", strerror(errno));
        }
        if (WIFEXITED(status)) {
                if (WEXITSTATUS(status) != 0) {
                        debug_f("preauth child exited with status %d",
                            WEXITSTATUS(status));
                        cleanup_exit(255);
                }
        } else if (WIFSIGNALED(status)) {
                error_f("preauth child terminated by signal %d",
                    WTERMSIG(status));
                cleanup_exit(signal_is_crash(WTERMSIG(status)) ?
                    EXIT_CHILD_CRASH : 255);
        } else {
                error_f("preauth child terminated abnormally (status=0x%x)",
                    status);
                cleanup_exit(EXIT_CHILD_CRASH);
        }
}

void
mm_request_send(int sock, enum monitor_reqtype type, struct sshbuf *m)
{
        size_t mlen = sshbuf_len(m);
        u_char buf[5];

        debug3_f("entering, type %d", type);

        if (mlen >= 0xffffffff)
                fatal_f("bad length %zu", mlen);
        POKE_U32(buf, mlen + 1);
        buf[4] = (u_char) type;         /* 1st byte of payload is mesg-type */
        if (atomicio(vwrite, sock, buf, sizeof(buf)) != sizeof(buf) ||
            atomicio(vwrite, sock, sshbuf_mutable_ptr(m), mlen) != mlen) {
                if (errno == EPIPE) {
                        debug3_f("monitor fd closed");
                        mm_reap();
                        cleanup_exit(255);
                }
                fatal_f("write: %s", strerror(errno));
        }
}

void
mm_request_receive(int sock, struct sshbuf *m)
{
        u_char buf[4], *p = NULL;
        u_int msg_len;
        int oerrno, r;

        debug3_f("entering");

        if (atomicio(read, sock, buf, sizeof(buf)) != sizeof(buf)) {
                if (errno == EPIPE) {
                        debug3_f("monitor fd closed");
                        mm_reap();
                        cleanup_exit(255);
                }
                fatal_f("read: %s", strerror(errno));
        }
        msg_len = PEEK_U32(buf);
        if (msg_len > 256 * 1024)
                fatal_f("read: bad msg_len %d", msg_len);
        sshbuf_reset(m);
        if ((r = sshbuf_reserve(m, msg_len, &p)) != 0)
                fatal_fr(r, "reserve");
        if (atomicio(read, sock, p, msg_len) != msg_len) {
                oerrno = errno;
                error_f("read: %s", strerror(errno));
                if (oerrno == EPIPE)
                        mm_reap();
                cleanup_exit(255);
        }
}

void
mm_request_receive_expect(int sock, enum monitor_reqtype type, struct sshbuf *m)
{
        u_char rtype;
        int r;

        debug3_f("entering, type %d", type);

        mm_request_receive(sock, m);
        if ((r = sshbuf_get_u8(m, &rtype)) != 0)
                fatal_fr(r, "parse");
        if (rtype != type)
                fatal_f("read: rtype %d != type %d", rtype, type);
}

#ifdef WITH_OPENSSL
DH *
mm_choose_dh(int min, int nbits, int max)
{
        BIGNUM *p, *g;
        int r;
        u_char success = 0;
        struct sshbuf *m;

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u32(m, min)) != 0 ||
            (r = sshbuf_put_u32(m, nbits)) != 0 ||
            (r = sshbuf_put_u32(m, max)) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_MODULI, m);

        debug3_f("waiting for MONITOR_ANS_MODULI");
        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_MODULI, m);

        if ((r = sshbuf_get_u8(m, &success)) != 0)
                fatal_fr(r, "parse success");
        if (success == 0)
                fatal_f("MONITOR_ANS_MODULI failed");

        if ((r = sshbuf_get_bignum2(m, &p)) != 0 ||
            (r = sshbuf_get_bignum2(m, &g)) != 0)
                fatal_fr(r, "parse group");

        debug3_f("remaining %zu", sshbuf_len(m));
        sshbuf_free(m);

        return (dh_new_group(g, p));
}
#endif

int
mm_sshkey_sign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
    const u_char *data, size_t datalen, const char *hostkey_alg,
    const char *sk_provider, const char *sk_pin, u_int compat)
{
        struct kex *kex = *pmonitor->m_pkex;
        struct sshbuf *m;
        u_int ndx = kex->host_key_index(key, 0, ssh);
        int r;

        debug3_f("entering");
        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u32(m, ndx)) != 0 ||
            (r = sshbuf_put_string(m, data, datalen)) != 0 ||
            (r = sshbuf_put_cstring(m, hostkey_alg)) != 0 ||
            (r = sshbuf_put_u32(m, compat)) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_SIGN, m);

        debug3_f("waiting for MONITOR_ANS_SIGN");
        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_SIGN, m);
        if ((r = sshbuf_get_string(m, sigp, lenp)) != 0)
                fatal_fr(r, "parse");
        sshbuf_free(m);

        return (0);
}

void
mm_decode_activate_server_options(struct ssh *ssh, struct sshbuf *m)
{
        const u_char *p;
        size_t len;
        u_int i;
        ServerOptions *newopts;
        int r;

        if ((r = sshbuf_get_string_direct(m, &p, &len)) != 0)
                fatal_fr(r, "parse opts");
        if (len != sizeof(*newopts))
                fatal_f("option block size mismatch");
        newopts = xcalloc(sizeof(*newopts), 1);
        memcpy(newopts, p, sizeof(*newopts));

#define M_CP_STROPT(x) do { \
                if (newopts->x != NULL && \
                    (r = sshbuf_get_cstring(m, &newopts->x, NULL)) != 0) \
                        fatal_fr(r, "parse %s", #x); \
        } while (0)
#define M_CP_STRARRAYOPT(x, nx) do { \
                newopts->x = newopts->nx == 0 ? \
                    NULL : xcalloc(newopts->nx, sizeof(*newopts->x)); \
                for (i = 0; i < newopts->nx; i++) { \
                        if ((r = sshbuf_get_cstring(m, \
                            &newopts->x[i], NULL)) != 0) \
                                fatal_fr(r, "parse %s", #x); \
                } \
        } while (0)
        /* See comment in servconf.h */
        COPY_MATCH_STRING_OPTS();
#undef M_CP_STROPT
#undef M_CP_STRARRAYOPT

        copy_set_server_options(&options, newopts, 1);
        log_change_level(options.log_level);
        log_verbose_reset();
        for (i = 0; i < options.num_log_verbose; i++)
                log_verbose_add(options.log_verbose[i]);
        free(newopts);
}

#define GETPW(b, id) \
        do { \
                if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) \
                        fatal_fr(r, "parse pw %s", #id); \
                if (len != sizeof(pw->id)) \
                        fatal_fr(r, "bad length for %s", #id); \
                memcpy(&pw->id, p, len); \
        } while (0)

struct passwd *
mm_getpwnamallow(struct ssh *ssh, const char *username)
{
        struct sshbuf *m;
        struct passwd *pw;
        size_t len;
        int r;
        u_char ok;
        const u_char *p;

        debug3_f("entering");

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_cstring(m, username)) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PWNAM, m);

        debug3_f("waiting for MONITOR_ANS_PWNAM");
        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PWNAM, m);

        if ((r = sshbuf_get_u8(m, &ok)) != 0)
                fatal_fr(r, "parse success");
        if (ok == 0) {
                pw = NULL;
                goto out;
        }

        /* XXX don't like passing struct passwd like this */
        pw = xcalloc(sizeof(*pw), 1);
        GETPW(m, pw_uid);
        GETPW(m, pw_gid);
#ifdef HAVE_STRUCT_PASSWD_PW_CHANGE
        GETPW(m, pw_change);
#endif
#ifdef HAVE_STRUCT_PASSWD_PW_EXPIRE
        GETPW(m, pw_expire);
#endif
        if ((r = sshbuf_get_cstring(m, &pw->pw_name, NULL)) != 0 ||
            (r = sshbuf_get_cstring(m, &pw->pw_passwd, NULL)) != 0 ||
#ifdef HAVE_STRUCT_PASSWD_PW_GECOS
            (r = sshbuf_get_cstring(m, &pw->pw_gecos, NULL)) != 0 ||
#endif
#ifdef HAVE_STRUCT_PASSWD_PW_CLASS
            (r = sshbuf_get_cstring(m, &pw->pw_class, NULL)) != 0 ||
#endif
            (r = sshbuf_get_cstring(m, &pw->pw_dir, NULL)) != 0 ||
            (r = sshbuf_get_cstring(m, &pw->pw_shell, NULL)) != 0)
                fatal_fr(r, "parse pw");

out:
        /* copy options block as a Match directive may have changed some */
        mm_decode_activate_server_options(ssh, m);
        server_process_permitopen(ssh);
        server_process_channel_timeouts(ssh);
        kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos);
        sshbuf_free(m);

        return (pw);
}

char *
mm_auth2_read_banner(void)
{
        struct sshbuf *m;
        char *banner;
        int r;

        debug3_f("entering");

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTH2_READ_BANNER, m);
        sshbuf_reset(m);

        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_AUTH2_READ_BANNER, m);
        if ((r = sshbuf_get_cstring(m, &banner, NULL)) != 0)
                fatal_fr(r, "parse");
        sshbuf_free(m);

        /* treat empty banner as missing banner */
        if (strlen(banner) == 0) {
                free(banner);
                banner = NULL;
        }
        return (banner);
}

/* Inform the privileged process about service and style */

void
mm_inform_authserv(char *service, char *style)
{
        struct sshbuf *m;
        int r;

        debug3_f("entering");

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_cstring(m, service)) != 0 ||
            (r = sshbuf_put_cstring(m, style ? style : "")) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHSERV, m);

        sshbuf_free(m);
}

/* Do the password authentication */
int
mm_auth_password(struct ssh *ssh, char *password)
{
        struct sshbuf *m;
        int r, authenticated = 0;
#ifdef USE_PAM
        u_int maxtries = 0;
#endif

        debug3_f("entering");

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_cstring(m, password)) != 0)
                fatal_fr(r, "assemble");
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHPASSWORD, m);

        debug3_f("waiting for MONITOR_ANS_AUTHPASSWORD");
        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_AUTHPASSWORD, m);

        if ((r = sshbuf_get_u32(m, &authenticated)) != 0)
                fatal_fr(r, "parse");
#ifdef USE_PAM
        if ((r = sshbuf_get_u32(m, &maxtries)) != 0)
                fatal_fr(r, "parse PAM");
        if (maxtries > INT_MAX)
                fatal_fr(r, "bad maxtries");
        sshpam_set_maxtries_reached(maxtries);
#endif

        sshbuf_free(m);

        debug3_f("user %sauthenticated", authenticated ? "" : "not ");
        return (authenticated);
}

int
mm_user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
    int pubkey_auth_attempt, struct sshauthopt **authoptp)
{
        return (mm_key_allowed(MM_USERKEY, NULL, NULL, key,
            pubkey_auth_attempt, authoptp));
}

int
mm_hostbased_key_allowed(struct ssh *ssh, struct passwd *pw,
    const char *user, const char *host, struct sshkey *key)
{
        return (mm_key_allowed(MM_HOSTKEY, user, host, key, 0, NULL));
}

int
mm_key_allowed(enum mm_keytype type, const char *user, const char *host,
    struct sshkey *key, int pubkey_auth_attempt, struct sshauthopt **authoptp)
{
        struct sshbuf *m;
        int r, allowed = 0;
        struct sshauthopt *opts = NULL;

        debug3_f("entering");

        if (authoptp != NULL)
                *authoptp = NULL;

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u32(m, type)) != 0 ||
            (r = sshbuf_put_cstring(m, user ? user : "")) != 0 ||
            (r = sshbuf_put_cstring(m, host ? host : "")) != 0 ||
            (r = sshkey_puts(key, m)) != 0 ||
            (r = sshbuf_put_u32(m, pubkey_auth_attempt)) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYALLOWED, m);

        debug3_f("waiting for MONITOR_ANS_KEYALLOWED");
        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_KEYALLOWED, m);

        if ((r = sshbuf_get_u32(m, &allowed)) != 0)
                fatal_fr(r, "parse");
        if (allowed && type == MM_USERKEY &&
            (r = sshauthopt_deserialise(m, &opts)) != 0)
                fatal_fr(r, "sshauthopt_deserialise");
        sshbuf_free(m);

        if (authoptp != NULL) {
                *authoptp = opts;
                opts = NULL;
        }
        sshauthopt_free(opts);

        return allowed;
}

/*
 * This key verify needs to send the key type along, because the
 * privileged parent makes the decision if the key is allowed
 * for authentication.
 */

int
mm_sshkey_verify(const struct sshkey *key, const u_char *sig, size_t siglen,
    const u_char *data, size_t datalen, const char *sigalg, u_int compat,
    struct sshkey_sig_details **sig_detailsp)
{
        struct sshbuf *m;
        u_int encoded_ret = 0;
        int r;
        u_char sig_details_present, flags;
        u_int counter;

        debug3_f("entering");

        if (sig_detailsp != NULL)
                *sig_detailsp = NULL;
        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshkey_puts(key, m)) != 0 ||
            (r = sshbuf_put_string(m, sig, siglen)) != 0 ||
            (r = sshbuf_put_string(m, data, datalen)) != 0 ||
            (r = sshbuf_put_cstring(m, sigalg == NULL ? "" : sigalg)) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYVERIFY, m);

        debug3_f("waiting for MONITOR_ANS_KEYVERIFY");
        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_KEYVERIFY, m);

        if ((r = sshbuf_get_u32(m, &encoded_ret)) != 0 ||
            (r = sshbuf_get_u8(m, &sig_details_present)) != 0)
                fatal_fr(r, "parse");
        if (sig_details_present && encoded_ret == 0) {
                if ((r = sshbuf_get_u32(m, &counter)) != 0 ||
                    (r = sshbuf_get_u8(m, &flags)) != 0)
                        fatal_fr(r, "parse sig_details");
                if (sig_detailsp != NULL) {
                        *sig_detailsp = xcalloc(1, sizeof(**sig_detailsp));
                        (*sig_detailsp)->sk_counter = counter;
                        (*sig_detailsp)->sk_flags = flags;
                }
        }

        sshbuf_free(m);

        if (encoded_ret != 0)
                return SSH_ERR_SIGNATURE_INVALID;
        return 0;
}

void
mm_send_keystate(struct ssh *ssh, struct monitor *monitor)
{
        struct sshbuf *m;
        int r;

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = ssh_packet_get_state(ssh, m)) != 0)
                fatal_fr(r, "ssh_packet_get_state");
        mm_request_send(monitor->m_recvfd, MONITOR_REQ_KEYEXPORT, m);
        debug3_f("Finished sending state");
        sshbuf_free(m);
}

int
mm_pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
{
        struct sshbuf *m;
        char *p, *msg;
        int success = 0, tmp1 = -1, tmp2 = -1, r;

        /* Kludge: ensure there are fds free to receive the pty/tty */
        if ((tmp1 = dup(pmonitor->m_recvfd)) == -1 ||
            (tmp2 = dup(pmonitor->m_recvfd)) == -1) {
                error_f("cannot allocate fds for pty");
                if (tmp1 >= 0)
                        close(tmp1);
                return 0;
        }
        close(tmp1);
        close(tmp2);

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTY, m);

        debug3_f("waiting for MONITOR_ANS_PTY");
        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PTY, m);

        if ((r = sshbuf_get_u32(m, &success)) != 0)
                fatal_fr(r, "parse success");
        if (success == 0) {
                debug3_f("pty alloc failed");
                sshbuf_free(m);
                return (0);
        }
        if ((r = sshbuf_get_cstring(m, &p, NULL)) != 0 ||
            (r = sshbuf_get_cstring(m, &msg, NULL)) != 0)
                fatal_fr(r, "parse");
        sshbuf_free(m);

        strlcpy(namebuf, p, namebuflen); /* Possible truncation */
        free(p);

        if ((r = sshbuf_put(loginmsg, msg, strlen(msg))) != 0)
                fatal_fr(r, "put loginmsg");
        free(msg);

        if ((*ptyfd = mm_receive_fd(pmonitor->m_recvfd)) == -1 ||
            (*ttyfd = mm_receive_fd(pmonitor->m_recvfd)) == -1)
                fatal_f("receive fds failed");

        /* Success */
        return (1);
}

void
mm_session_pty_cleanup2(Session *s)
{
        struct sshbuf *m;
        int r;

        if (s->ttyfd == -1)
                return;
        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_cstring(m, s->tty)) != 0)
                fatal_fr(r, "assmble");
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTYCLEANUP, m);
        sshbuf_free(m);

        /* closed dup'ed master */
        if (s->ptymaster != -1 && close(s->ptymaster) == -1)
                error("close(s->ptymaster/%d): %s",
                    s->ptymaster, strerror(errno));

        /* unlink pty from session */
        s->ttyfd = -1;
}

#ifdef USE_PAM
void
mm_start_pam(struct ssh *ssh)
{
        struct sshbuf *m;

        debug3("%s entering", __func__);
        if (!options.use_pam)
                fatal("UsePAM=no, but ended up in %s anyway", __func__);
        if ((m = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PAM_START, m);

        sshbuf_free(m);
}

u_int
mm_do_pam_account(void)
{
        struct sshbuf *m;
        u_int ret;
        char *msg;
        size_t msglen;
        int r;

        debug3("%s entering", __func__);
        if (!options.use_pam)
                fatal("UsePAM=no, but ended up in %s anyway", __func__);

        if ((m = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PAM_ACCOUNT, m);

        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_PAM_ACCOUNT, m);
        if ((r = sshbuf_get_u32(m, &ret)) != 0 ||
            (r = sshbuf_get_cstring(m, &msg, &msglen)) != 0 ||
            (r = sshbuf_put(loginmsg, msg, msglen)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));

        free(msg);
        sshbuf_free(m);

        debug3("%s returning %d", __func__, ret);

        return (ret);
}

void *
mm_sshpam_init_ctx(Authctxt *authctxt)
{
        struct sshbuf *m;
        int r, success;

        debug3("%s", __func__);
        if ((m = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PAM_INIT_CTX, m);
        debug3("%s: waiting for MONITOR_ANS_PAM_INIT_CTX", __func__);
        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_PAM_INIT_CTX, m);
        if ((r = sshbuf_get_u32(m, &success)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));
        if (success == 0) {
                debug3("%s: pam_init_ctx failed", __func__);
                sshbuf_free(m);
                return (NULL);
        }
        sshbuf_free(m);
        return (authctxt);
}

int
mm_sshpam_query(void *ctx, char **name, char **info,
    u_int *num, char ***prompts, u_int **echo_on)
{
        struct sshbuf *m;
        u_int i, n;
        int r, ret;

        debug3("%s", __func__);
        if ((m = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PAM_QUERY, m);
        debug3("%s: waiting for MONITOR_ANS_PAM_QUERY", __func__);
        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PAM_QUERY, m);
        if ((r = sshbuf_get_u32(m, &ret)) != 0 ||
            (r = sshbuf_get_cstring(m, name, NULL)) != 0 ||
            (r = sshbuf_get_cstring(m, info, NULL)) != 0 ||
            (r = sshbuf_get_u32(m, &n)) != 0 ||
            (r = sshbuf_get_u32(m, num)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));
        debug3("%s: pam_query returned %d", __func__, ret);
        sshpam_set_maxtries_reached(n);
        if (*num > PAM_MAX_NUM_MSG)
                fatal("%s: received %u PAM messages, expected <= %u",
                    __func__, *num, PAM_MAX_NUM_MSG);
        *prompts = xcalloc((*num + 1), sizeof(char *));
        *echo_on = xcalloc((*num + 1), sizeof(u_int));
        for (i = 0; i < *num; ++i) {
                if ((r = sshbuf_get_cstring(m, &((*prompts)[i]), NULL)) != 0 ||
                    (r = sshbuf_get_u32(m, &((*echo_on)[i]))) != 0)
                        fatal("%s: buffer error: %s", __func__, ssh_err(r));
        }
        sshbuf_free(m);
        return (ret);
}

int
mm_sshpam_respond(void *ctx, u_int num, char **resp)
{
        struct sshbuf *m;
        u_int n, i;
        int r, ret;

        debug3("%s", __func__);
        if ((m = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        if ((r = sshbuf_put_u32(m, num)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));
        for (i = 0; i < num; ++i) {
                if ((r = sshbuf_put_cstring(m, resp[i])) != 0)
                        fatal("%s: buffer error: %s", __func__, ssh_err(r));
        }
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PAM_RESPOND, m);
        debug3("%s: waiting for MONITOR_ANS_PAM_RESPOND", __func__);
        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_PAM_RESPOND, m);
        if ((r = sshbuf_get_u32(m, &n)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));
        ret = (int)n; /* XXX */
        debug3("%s: pam_respond returned %d", __func__, ret);
        sshbuf_free(m);
        return (ret);
}

void
mm_sshpam_free_ctx(void *ctxtp)
{
        struct sshbuf *m;

        debug3("%s", __func__);
        if ((m = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PAM_FREE_CTX, m);
        debug3("%s: waiting for MONITOR_ANS_PAM_FREE_CTX", __func__);
        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_PAM_FREE_CTX, m);
        sshbuf_free(m);
}
#endif /* USE_PAM */

/* Request process termination */

void
mm_terminate(void)
{
        struct sshbuf *m;

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_TERM, m);
        sshbuf_free(m);
}

static void
mm_chall_setup(char **name, char **infotxt, u_int *numprompts,
    char ***prompts, u_int **echo_on)
{
        *name = xstrdup("");
        *infotxt = xstrdup("");
        *numprompts = 1;
        *prompts = xcalloc(*numprompts, sizeof(char *));
        *echo_on = xcalloc(*numprompts, sizeof(u_int));
        (*echo_on)[0] = 0;
}

int
mm_bsdauth_query(void *ctx, char **name, char **infotxt,
   u_int *numprompts, char ***prompts, u_int **echo_on)
{
        struct sshbuf *m;
        u_int success;
        char *challenge;
        int r;

        debug3_f("entering");

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_BSDAUTHQUERY, m);

        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_BSDAUTHQUERY, m);
        if ((r = sshbuf_get_u32(m, &success)) != 0)
                fatal_fr(r, "parse success");
        if (success == 0) {
                debug3_f("no challenge");
                sshbuf_free(m);
                return (-1);
        }

        /* Get the challenge, and format the response */
        if ((r = sshbuf_get_cstring(m, &challenge, NULL)) != 0)
                fatal_fr(r, "parse challenge");
        sshbuf_free(m);

        mm_chall_setup(name, infotxt, numprompts, prompts, echo_on);
        (*prompts)[0] = challenge;

        debug3_f("received challenge: %s", challenge);

        return (0);
}

int
mm_bsdauth_respond(void *ctx, u_int numresponses, char **responses)
{
        struct sshbuf *m;
        int r, authok;

        debug3_f("entering");
        if (numresponses != 1)
                return (-1);

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_cstring(m, responses[0])) != 0)
                fatal_fr(r, "assemble");
        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_BSDAUTHRESPOND, m);

        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_BSDAUTHRESPOND, m);

        if ((r = sshbuf_get_u32(m, &authok)) != 0)
                fatal_fr(r, "parse");
        sshbuf_free(m);

        return ((authok == 0) ? -1 : 0);
}

#ifdef SSH_AUDIT_EVENTS
void
mm_audit_event(struct ssh *ssh, ssh_audit_event_t event)
{
        struct sshbuf *m;
        int r;

        debug3("%s entering", __func__);

        if ((m = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        if ((r = sshbuf_put_u32(m, event)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUDIT_EVENT, m);
        sshbuf_free(m);
}

void
mm_audit_run_command(const char *command)
{
        struct sshbuf *m;
        int r;

        debug3("%s entering command %s", __func__, command);

        if ((m = sshbuf_new()) == NULL)
                fatal("%s: sshbuf_new failed", __func__);
        if ((r = sshbuf_put_cstring(m, command)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUDIT_COMMAND, m);
        sshbuf_free(m);
}
#endif /* SSH_AUDIT_EVENTS */

#ifdef GSSAPI
OM_uint32
mm_ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID goid)
{
        struct sshbuf *m;
        OM_uint32 major;
        int r;

        /* Client doesn't get to see the context */
        *ctx = NULL;

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_string(m, goid->elements, goid->length)) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSETUP, m);
        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSETUP, m);

        if ((r = sshbuf_get_u32(m, &major)) != 0)
                fatal_fr(r, "parse");

        sshbuf_free(m);
        return (major);
}

OM_uint32
mm_ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *in,
    gss_buffer_desc *out, OM_uint32 *flagsp)
{
        struct sshbuf *m;
        OM_uint32 major;
        u_int flags;
        int r;

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_string(m, in->value, in->length)) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSTEP, m);
        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSTEP, m);

        if ((r = sshbuf_get_u32(m, &major)) != 0 ||
            (r = ssh_gssapi_get_buffer_desc(m, out)) != 0)
                fatal_fr(r, "parse");
        if (flagsp != NULL) {
                if ((r = sshbuf_get_u32(m, &flags)) != 0)
                        fatal_fr(r, "parse flags");
                *flagsp = flags;
        }

        sshbuf_free(m);

        return (major);
}

OM_uint32
mm_ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
{
        struct sshbuf *m;
        OM_uint32 major;
        int r;

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_string(m, gssbuf->value, gssbuf->length)) != 0 ||
            (r = sshbuf_put_string(m, gssmic->value, gssmic->length)) != 0)
                fatal_fr(r, "assemble");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSCHECKMIC, m);
        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_GSSCHECKMIC, m);

        if ((r = sshbuf_get_u32(m, &major)) != 0)
                fatal_fr(r, "parse");
        sshbuf_free(m);
        return(major);
}

int
mm_ssh_gssapi_userok(char *user)
{
        struct sshbuf *m;
        int r, authenticated = 0;

        if ((m = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUSEROK, m);
        mm_request_receive_expect(pmonitor->m_recvfd,
            MONITOR_ANS_GSSUSEROK, m);

        if ((r = sshbuf_get_u32(m, &authenticated)) != 0)
                fatal_fr(r, "parse");

        sshbuf_free(m);
        debug3_f("user %sauthenticated", authenticated ? "" : "not ");
        return (authenticated);
}
#endif /* GSSAPI */

/*
 * Inform channels layer of permitopen options for a single forwarding
 * direction (local/remote).
 */
static void
server_process_permitopen_list(struct ssh *ssh, int listen,
    char **opens, u_int num_opens)
{
        u_int i;
        int port;
        char *host, *arg, *oarg;
        int where = listen ? FORWARD_REMOTE : FORWARD_LOCAL;
        const char *what = listen ? "permitlisten" : "permitopen";

        channel_clear_permission(ssh, FORWARD_ADM, where);
        if (num_opens == 0)
                return; /* permit any */

        /* handle keywords: "any" / "none" */
        if (num_opens == 1 && strcmp(opens[0], "any") == 0)
                return;
        if (num_opens == 1 && strcmp(opens[0], "none") == 0) {
                channel_disable_admin(ssh, where);
                return;
        }
        /* Otherwise treat it as a list of permitted host:port */
        for (i = 0; i < num_opens; i++) {
                oarg = arg = xstrdup(opens[i]);
                host = hpdelim(&arg);
                if (host == NULL)
                        fatal_f("missing host in %s", what);
                host = cleanhostname(host);
                if (arg == NULL || ((port = permitopen_port(arg)) < 0))
                        fatal_f("bad port number in %s", what);
                /* Send it to channels layer */
                channel_add_permission(ssh, FORWARD_ADM,
                    where, host, port);
                free(oarg);
        }
}

/*
 * Inform channels layer of permitopen options from configuration.
 */
void
server_process_permitopen(struct ssh *ssh)
{
        server_process_permitopen_list(ssh, 0,
            options.permitted_opens, options.num_permitted_opens);
        server_process_permitopen_list(ssh, 1,
            options.permitted_listens, options.num_permitted_listens);
}

void
server_process_channel_timeouts(struct ssh *ssh)
{
        u_int i, secs;
        char *type;

        debug3_f("setting %u timeouts", options.num_channel_timeouts);
        channel_clear_timeouts(ssh);
        for (i = 0; i < options.num_channel_timeouts; i++) {
                if (parse_pattern_interval(options.channel_timeouts[i],
                    &type, &secs) != 0) {
                        fatal_f("internal error: bad timeout %s",
                            options.channel_timeouts[i]);
                }
                channel_add_timeout(ssh, type, secs);
                free(type);
        }
}

struct connection_info *
server_get_connection_info(struct ssh *ssh, int populate, int use_dns)
{
        static struct connection_info ci;

        if (ssh == NULL || !populate)
                return &ci;
        ci.host = use_dns ? ssh_remote_hostname(ssh) : ssh_remote_ipaddr(ssh);
        ci.address = ssh_remote_ipaddr(ssh);
        ci.laddress = ssh_local_ipaddr(ssh);
        ci.lport = ssh_local_port(ssh);
        ci.rdomain = ssh_packet_rdomain_in(ssh);
        return &ci;
}