/* $OpenBSD: monitor.c,v 1.172 2017/06/24 06:34:38 djm Exp $ */ /* * Copyright 2002 Niels Provos * Copyright 2002 Markus Friedl * 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 #include #include #include #include #ifdef WITH_OPENSSL #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #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" #include #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" #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 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 static int monitor_read_log(struct monitor *); static Authctxt *authctxt; /* 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}, {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, {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, 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(Authctxt *_authctxt, struct monitor *pmonitor) { struct ssh *ssh = active_state; /* XXX */ 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)); 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(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(auth_method)) authenticated = 0; } if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { auth_log(authctxt, authenticated, partial, auth_method, auth_submethod); if (!partial && !authenticated) 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_packet_set_log_preamble(ssh, "user %s", 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); 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 (!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); } 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 = NULL; u_char *p = NULL, *signature = NULL; char *alg = NULL; size_t datlen, siglen, alglen; int r, is_proof = 0; u_int keyid; 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) 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, 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, alg, 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(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(int sock, Buffer *m) { struct ssh *ssh = active_state; /* XXX */ 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, "*"); buffer_put_cstring(m, pwent->pw_gecos); buffer_put_cstring(m, pwent->pw_class); buffer_put_cstring(m, pwent->pw_dir); buffer_put_cstring(m, pwent->pw_shell); out: ssh_packet_set_log_preamble(ssh, "%suser %s", authctxt->valid ? "authenticating" : "invalid ", authctxt->user); 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 (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); 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; if (!options.password_authentication) fatal("%s: password authentication not enabled", __func__); 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); } int mm_answer_bsdauthquery(int sock, Buffer *m) { char *name, *infotxt; u_int numprompts; u_int *echo_on; char **prompts; u_int success; 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; 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 (!options.kbd_interactive_authentication) fatal("%s: kbd-int authentication not enabled", __func__); if (authctxt->as == NULL) 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); auth_method = "keyboard-interactive"; auth_submethod = "bsdauth"; return (authok != 0); } int mm_answer_keyallowed(int sock, Buffer *m) { struct sshkey *key; char *cuser, *chost; u_char *blob; u_int bloblen, pubkey_auth_attempt; enum mm_keytype type = 0; int allowed = 0; debug3("%s entering", __func__); type = buffer_get_int(m); cuser = buffer_get_string(m, NULL); chost = buffer_get_string(m, NULL); blob = buffer_get_string(m, &bloblen); pubkey_auth_attempt = buffer_get_int(m); key = key_from_blob(blob, bloblen); debug3("%s: key_from_blob: %p", __func__, key); if (key != NULL && authctxt->valid) { /* These should not make it past the privsep child */ if (key_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: allowed = options.pubkey_authentication && !auth2_key_already_used(authctxt, key) && match_pattern_list(sshkey_ssh_name(key), options.pubkey_key_types, 0) == 1 && user_key_allowed(authctxt->pw, key, pubkey_auth_attempt); auth_method = "publickey"; if (options.pubkey_authentication && (!pubkey_auth_attempt || allowed != 1)) auth_clear_options(); break; case MM_HOSTKEY: allowed = options.hostbased_authentication && !auth2_key_already_used(authctxt, key) && match_pattern_list(sshkey_ssh_name(key), options.hostbased_key_types, 0) == 1 && hostbased_key_allowed(authctxt->pw, cuser, chost, key); auth2_record_info(authctxt, "client user \"%.100s\", client host \"%.100s\"", cuser, chost); auth_method = "hostbased"; break; default: fatal("%s: unknown key type %d", __func__, type); break; } } debug3("%s: key is %s", __func__, allowed ? "allowed" : "not allowed"); auth2_record_key(authctxt, 0, key); sshkey_free(key); /* clear temporarily storage (used by verify) */ monitor_reset_key_state(); if (allowed) { /* Save temporarily for comparison in verify */ key_blob = blob; key_bloblen = bloblen; key_blobtype = type; hostbased_cuser = cuser; hostbased_chost = chost; } else { /* Log failed attempt */ auth_log(authctxt, 0, 0, auth_method, NULL); free(blob); free(cuser); free(chost); } buffer_clear(m); buffer_put_int(m, allowed); buffer_put_int(m, forced_command != NULL); mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); return (0); } static int monitor_valid_userblob(u_char *data, u_int datalen) { Buffer b; u_char *p; char *userstyle, *cp; u_int len; int fail = 0; buffer_init(&b); buffer_append(&b, data, datalen); if (datafellows & SSH_OLD_SESSIONID) { p = buffer_ptr(&b); len = buffer_len(&b); if ((session_id2 == NULL) || (len < session_id2_len) || (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) fail++; buffer_consume(&b, session_id2_len); } else { p = buffer_get_string(&b, &len); if ((session_id2 == NULL) || (len != session_id2_len) || (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) fail++; free(p); } if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) fail++; cp = buffer_get_cstring(&b, NULL); 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); buffer_skip_string(&b); if (datafellows & SSH_BUG_PKAUTH) { if (!buffer_get_char(&b)) fail++; } else { cp = buffer_get_cstring(&b, NULL); if (strcmp("publickey", cp) != 0) fail++; free(cp); if (!buffer_get_char(&b)) fail++; buffer_skip_string(&b); } buffer_skip_string(&b); if (buffer_len(&b) != 0) fail++; buffer_free(&b); return (fail == 0); } static int monitor_valid_hostbasedblob(u_char *data, u_int datalen, char *cuser, char *chost) { Buffer b; char *p, *userstyle; u_int len; int fail = 0; buffer_init(&b); buffer_append(&b, data, datalen); p = buffer_get_string(&b, &len); if ((session_id2 == NULL) || (len != session_id2_len) || (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) fail++; free(p); if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) fail++; p = buffer_get_cstring(&b, NULL); xasprintf(&userstyle, "%s%s%s", authctxt->user, authctxt->style ? ":" : "", authctxt->style ? authctxt->style : ""); if (strcmp(userstyle, p) != 0) { logit("wrong user name passed to monitor: expected %s != %.100s", userstyle, p); fail++; } free(userstyle); free(p); buffer_skip_string(&b); /* service */ p = buffer_get_cstring(&b, NULL); if (strcmp(p, "hostbased") != 0) fail++; free(p); buffer_skip_string(&b); /* pkalg */ buffer_skip_string(&b); /* pkblob */ /* verify client host, strip trailing dot if necessary */ p = buffer_get_string(&b, NULL); if (((len = strlen(p)) > 0) && p[len - 1] == '.') p[len - 1] = '\0'; if (strcmp(p, chost) != 0) fail++; free(p); /* verify client user */ p = buffer_get_string(&b, NULL); if (strcmp(p, cuser) != 0) fail++; free(p); if (buffer_len(&b) != 0) fail++; buffer_free(&b); return (fail == 0); } int mm_answer_keyverify(int sock, struct sshbuf *m) { struct sshkey *key; u_char *signature, *data, *blob; size_t signaturelen, datalen, bloblen; int r, ret, valid_data = 0, encoded_ret; if ((r = sshbuf_get_string(m, &blob, &bloblen)) != 0 || (r = sshbuf_get_string(m, &signature, &signaturelen)) != 0 || (r = sshbuf_get_string(m, &data, &datalen)) != 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__); /* 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(data, datalen); auth_method = "publickey"; break; case MM_HOSTKEY: valid_data = monitor_valid_hostbasedblob(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__); ret = sshkey_verify(key, signature, signaturelen, data, datalen, active_state->compat); debug3("%s: %s %p signature %s", __func__, auth_method, key, (ret == 0) ? "verified" : "unverified"); auth2_record_key(authctxt, ret == 0, key); free(blob); free(signature); free(data); monitor_reset_key_state(); sshkey_free(key); 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) fatal("%s: buffer error: %s", __func__, ssh_err(r)); mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); return ret == 0; } static void mm_record_login(Session *s, struct passwd *pw) { struct ssh *ssh = active_state; /* XXX */ socklen_t fromlen; struct sockaddr_storage from; /* * Get IP address of client. If the connection is not a socket, let * the address be 0.0.0.0. */ memset(&from, 0, sizeof(from)); fromlen = sizeof(from); if (packet_connection_is_on_socket()) { if (getpeername(packet_get_connection_in(), (struct sockaddr *)&from, &fromlen) < 0) { debug("getpeername: %.100s", strerror(errno)); cleanup_exit(255); } } /* 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(int sock, Buffer *m) { extern struct monitor *pmonitor; Session *s; int res, fd0; debug3("%s entering", __func__); buffer_clear(m); s = session_new(); if (s == NULL) goto error; s->authctxt = authctxt; s->pw = authctxt->pw; s->pid = pmonitor->m_pid; res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); if (res == 0) goto error; pty_setowner(authctxt->pw, s->tty); buffer_put_int(m, 1); buffer_put_cstring(m, s->tty); /* We need to trick ttyslot */ if (dup2(s->ttyfd, 0) == -1) fatal("%s: dup2", __func__); mm_record_login(s, authctxt->pw); /* Now we can close the file descriptor again */ close(0); /* send messages generated by record_login */ buffer_put_string(m, buffer_ptr(&loginmsg), buffer_len(&loginmsg)); buffer_clear(&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)) < 0) fatal("%s: open(/dev/null): %s", __func__, strerror(errno)); if (fd0 != 0) error("%s: fd0 %d != 0", __func__, fd0); /* slave is not needed */ close(s->ttyfd); s->ttyfd = s->ptyfd; /* no need to dup() because nobody closes ptyfd */ s->ptymaster = s->ptyfd; debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ttyfd); return (0); error: if (s != NULL) mm_session_close(s); buffer_put_int(m, 0); mm_request_send(sock, MONITOR_ANS_PTY, m); return (0); } int mm_answer_pty_cleanup(int sock, Buffer *m) { Session *s; char *tty; debug3("%s entering", __func__); tty = buffer_get_string(m, NULL); if ((s = session_by_tty(tty)) != NULL) mm_session_close(s); buffer_clear(m); free(tty); return (0); } int mm_answer_term(int sock, Buffer *req) { extern struct monitor *pmonitor; int res, status; debug3("%s: tearing down sessions", __func__); /* The child is terminating */ session_destroy_all(&mm_session_close); while (waitpid(pmonitor->m_pid, &status, 0) == -1) if (errno != EINTR) exit(1); res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; /* Terminate process */ exit(res); } void monitor_clear_keystate(struct monitor *pmonitor) { struct ssh *ssh = active_state; /* XXX */ ssh_clear_newkeys(ssh, MODE_IN); ssh_clear_newkeys(ssh, MODE_OUT); sshbuf_free(child_state); child_state = NULL; } void monitor_apply_keystate(struct monitor *pmonitor) { struct ssh *ssh = active_state; /* XXX */ 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] = kexdh_server; kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; kex->kex[KEX_ECDH_SHA2] = kexecdh_server; #endif kex->kex[KEX_C25519_SHA256] = kexc25519_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 requries careful sanity checking */ void mm_get_keystate(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)) < 0) error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno)); if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) < 0) 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(int sock, Buffer *m) { gss_OID_desc goid; OM_uint32 major; u_int len; if (!options.gss_authentication) fatal("%s: GSSAPI authentication not enabled", __func__); goid.elements = buffer_get_string(m, &len); goid.length = len; major = ssh_gssapi_server_ctx(&gsscontext, &goid); free(goid.elements); buffer_clear(m); buffer_put_int(m, major); 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(int sock, Buffer *m) { gss_buffer_desc in; gss_buffer_desc out = GSS_C_EMPTY_BUFFER; OM_uint32 major, minor; OM_uint32 flags = 0; /* GSI needs this */ u_int len; if (!options.gss_authentication) fatal("%s: GSSAPI authentication not enabled", __func__); in.value = buffer_get_string(m, &len); in.length = len; major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); free(in.value); buffer_clear(m); buffer_put_int(m, major); buffer_put_string(m, out.value, out.length); buffer_put_int(m, flags); 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(int sock, Buffer *m) { gss_buffer_desc gssbuf, mic; OM_uint32 ret; u_int len; if (!options.gss_authentication) fatal("%s: GSSAPI authentication not enabled", __func__); gssbuf.value = buffer_get_string(m, &len); gssbuf.length = len; mic.value = buffer_get_string(m, &len); mic.length = len; ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); free(gssbuf.value); free(mic.value); buffer_clear(m); buffer_put_int(m, ret); 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(int sock, Buffer *m) { int authenticated; const char *displayname; if (!options.gss_authentication) fatal("%s: GSSAPI authentication not enabled", __func__); authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); buffer_clear(m); buffer_put_int(m, authenticated); 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 */