/* $NetBSD: monitor.c,v 1.29.2.2 2024/10/08 11:22:36 martin Exp $ */ /* $OpenBSD: monitor.c,v 1.237 2023/08/16 16:14:11 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 "includes.h" __RCSID("$NetBSD: monitor.c,v 1.29.2.2 2024/10/08 11:22:36 martin Exp $"); #include #include #include #include #include #ifdef WITH_OPENSSL #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "atomicio.h" #include "xmalloc.h" #include "ssh.h" #include "sshkey.h" #include "sshbuf.h" #include "hostfile.h" #include "auth.h" #include "cipher.h" #include "kex.h" #include "dh.h" #include "packet.h" #include "auth-options.h" #include "sshpty.h" #include "channels.h" #include "session.h" #include "sshlogin.h" #include "canohost.h" #include "log.h" #include "misc.h" #include "servconf.h" #include "monitor.h" #ifdef GSSAPI #include "ssh-gss.h" #endif #include "monitor_wrap.h" #include "monitor_fdpass.h" #include "compat.h" #include "ssh2.h" #include "authfd.h" #include "match.h" #include "ssherr.h" #include "sk-api.h" #include "pfilter.h" #ifdef GSSAPI static Gssctxt *gsscontext = NULL; #endif /* Imports */ extern ServerOptions options; extern u_int utmp_len; extern struct sshbuf *loginmsg; extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */ /* State exported from the child */ static struct sshbuf *child_state; /* Functions on the monitor that answer unprivileged requests */ int mm_answer_moduli(struct ssh *, int, struct sshbuf *); int mm_answer_sign(struct ssh *, int, struct sshbuf *); int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *); int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *); int mm_answer_authserv(struct ssh *, int, struct sshbuf *); int mm_answer_authpassword(struct ssh *, int, struct sshbuf *); int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *); int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *); int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *); int mm_answer_keyverify(struct ssh *, int, struct sshbuf *); int mm_answer_pty(struct ssh *, int, struct sshbuf *); int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *); int mm_answer_term(struct ssh *, int, struct sshbuf *); int mm_answer_sesskey(struct ssh *, int, struct sshbuf *); int mm_answer_sessid(struct ssh *, int, struct sshbuf *); #ifdef USE_PAM int mm_answer_pam_start(struct ssh *, int, struct sshbuf *); int mm_answer_pam_account(struct ssh *, int, struct sshbuf *); int mm_answer_pam_init_ctx(struct ssh *, int, struct sshbuf *); int mm_answer_pam_query(struct ssh *, int, struct sshbuf *); int mm_answer_pam_respond(struct ssh *, int, struct sshbuf *); int mm_answer_pam_free_ctx(struct ssh *, int, struct sshbuf *); #endif #ifdef KRB5 int mm_answer_krb5(struct ssh *, int, struct sshbuf *); #endif #ifdef GSSAPI int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *); int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *); int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *); int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *); #endif /* local state for key verify */ static u_char *key_blob = NULL; static size_t key_bloblen = 0; static u_int key_blobtype = MM_NOKEY; static struct sshauthopt *key_opts = NULL; static char *hostbased_cuser = NULL; static char *hostbased_chost = NULL; static const char *auth_method = "unknown"; static const char *auth_submethod = NULL; static u_int session_id2_len = 0; static u_char *session_id2 = NULL; static pid_t monitor_child_pid; struct mon_table { enum monitor_reqtype type; int flags; int (*f)(struct ssh *, int, struct sshbuf *); }; #define MON_ISAUTH 0x0004 /* Required for Authentication */ #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */ #define MON_ONCE 0x0010 /* Disable after calling */ #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */ #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE) #define MON_PERMIT 0x1000 /* Request is permitted */ static int monitor_read(struct ssh *, struct monitor *, struct mon_table *, struct mon_table **); static int monitor_read_log(struct monitor *); struct mon_table mon_dispatch_proto20[] = { #ifdef WITH_OPENSSL {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, #endif {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, #ifdef USE_PAM {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start}, {MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account}, {MONITOR_REQ_PAM_INIT_CTX, MON_ISAUTH, mm_answer_pam_init_ctx}, {MONITOR_REQ_PAM_QUERY, MON_ISAUTH, mm_answer_pam_query}, {MONITOR_REQ_PAM_RESPOND, MON_ISAUTH, mm_answer_pam_respond}, {MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx}, #endif #ifdef BSD_AUTH {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, #endif {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, #ifdef KRB5 {MONITOR_REQ_KRB5, MON_ONCE|MON_AUTH, mm_answer_krb5}, #endif #ifdef GSSAPI {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx}, {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, #endif {0, 0, NULL} }; struct mon_table mon_dispatch_postauth20[] = { #ifdef WITH_OPENSSL {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, #endif {MONITOR_REQ_SIGN, 0, mm_answer_sign}, {MONITOR_REQ_PTY, 0, mm_answer_pty}, {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup}, {MONITOR_REQ_TERM, 0, mm_answer_term}, {0, 0, NULL} }; struct mon_table *mon_dispatch; /* Specifies if a certain message is allowed at the moment */ static void monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit) { while (ent->f != NULL) { if (ent->type == type) { ent->flags &= ~MON_PERMIT; ent->flags |= permit ? MON_PERMIT : 0; return; } ent++; } } static void monitor_permit_authentications(int permit) { struct mon_table *ent = mon_dispatch; while (ent->f != NULL) { if (ent->flags & MON_AUTH) { ent->flags &= ~MON_PERMIT; ent->flags |= permit ? MON_PERMIT : 0; } ent++; } } void monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor) { struct mon_table *ent; int authenticated = 0, partial = 0; Authctxt *authctxt = ssh->authctxt; debug3("preauth child monitor started"); if (pmonitor->m_recvfd >= 0) close(pmonitor->m_recvfd); if (pmonitor->m_log_sendfd >= 0) close(pmonitor->m_log_sendfd); pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1; memset(authctxt, 0, sizeof(*authctxt)); ssh->authctxt = authctxt; mon_dispatch = mon_dispatch_proto20; /* Permit requests for moduli and signatures */ monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); /* The first few requests do not require asynchronous access */ while (!authenticated) { partial = 0; auth_method = "unknown"; auth_submethod = NULL; auth2_authctxt_reset_info(authctxt); authenticated = (monitor_read(ssh, pmonitor, mon_dispatch, &ent) == 1); /* Special handling for multiple required authentications */ if (options.num_auth_methods != 0) { if (authenticated && !auth2_update_methods_lists(authctxt, auth_method, auth_submethod)) { debug3_f("method %s: partial", auth_method); authenticated = 0; partial = 1; } } if (authenticated) { if (!(ent->flags & MON_AUTHDECIDE)) fatal_f("unexpected authentication from %d", ent->type); if (authctxt->pw->pw_uid == 0 && !auth_root_allowed(ssh, auth_method)) authenticated = 0; #ifdef USE_PAM /* PAM needs to perform account checks after auth */ if (options.use_pam && authenticated) { struct sshbuf *m; if ((m = sshbuf_new()) == NULL) fatal("%s: sshbuf_new failed", __func__); mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_PAM_ACCOUNT, m); authenticated = mm_answer_pam_account(ssh, pmonitor->m_sendfd, m); sshbuf_free(m); } #endif } if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { auth_log(ssh, authenticated, partial, auth_method, auth_submethod); if (!partial && !authenticated) { authctxt->failures++; } if (authenticated || partial) { auth2_update_session_info(authctxt, auth_method, auth_submethod); } } if (authctxt->failures > options.max_authtries) { pfilter_notify(1); /* Shouldn't happen */ fatal_f("privsep child made too many authentication " "attempts"); } } if (!authctxt->valid) { pfilter_notify(1); fatal_f("authenticated invalid user"); } if (strcmp(auth_method, "unknown") == 0) { pfilter_notify(1); fatal_f("authentication method name unknown"); } debug_f("user %s authenticated by privileged process", authctxt->user); ssh->authctxt = NULL; ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); mm_get_keystate(ssh, pmonitor); /* Drain any buffered messages from the child */ while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0) ; if (pmonitor->m_recvfd >= 0) close(pmonitor->m_recvfd); if (pmonitor->m_log_sendfd >= 0) close(pmonitor->m_log_sendfd); pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1; } static void monitor_set_child_handler(pid_t pid) { monitor_child_pid = pid; } static void monitor_child_handler(int sig) { kill(monitor_child_pid, sig); } void monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor) { close(pmonitor->m_recvfd); pmonitor->m_recvfd = -1; monitor_set_child_handler(pmonitor->m_pid); ssh_signal(SIGHUP, &monitor_child_handler); ssh_signal(SIGTERM, &monitor_child_handler); ssh_signal(SIGINT, &monitor_child_handler); mon_dispatch = mon_dispatch_postauth20; /* Permit requests for moduli and signatures */ monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); if (auth_opts->permit_pty_flag) { monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); } for (;;) monitor_read(ssh, pmonitor, mon_dispatch, NULL); } static int monitor_read_log(struct monitor *pmonitor) { struct sshbuf *logmsg; u_int len, level, forced; char *msg; u_char *p; int r; if ((logmsg = sshbuf_new()) == NULL) fatal_f("sshbuf_new"); /* Read length */ if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0) fatal_fr(r, "reserve len"); if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) { if (errno == EPIPE) { sshbuf_free(logmsg); debug_f("child log fd closed"); close(pmonitor->m_log_recvfd); pmonitor->m_log_recvfd = -1; return -1; } fatal_f("log fd read: %s", strerror(errno)); } if ((r = sshbuf_get_u32(logmsg, &len)) != 0) fatal_fr(r, "parse len"); if (len <= 4 || len > 8192) fatal_f("invalid log message length %u", len); /* Read severity, message */ sshbuf_reset(logmsg); if ((r = sshbuf_reserve(logmsg, len, &p)) != 0) fatal_fr(r, "reserve msg"); if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len) fatal_f("log fd read: %s", strerror(errno)); if ((r = sshbuf_get_u32(logmsg, &level)) != 0 || (r = sshbuf_get_u32(logmsg, &forced)) != 0 || (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0) fatal_fr(r, "parse"); /* Log it */ if (log_level_name(level) == NULL) fatal_f("invalid log level %u (corrupted message?)", level); sshlogdirect(level, forced, "%s [preauth]", msg); sshbuf_free(logmsg); free(msg); return 0; } static int monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent, struct mon_table **pent) { struct sshbuf *m; int r, ret; u_char type; struct pollfd pfd[2]; for (;;) { memset(&pfd, 0, sizeof(pfd)); pfd[0].fd = pmonitor->m_sendfd; pfd[0].events = POLLIN; pfd[1].fd = pmonitor->m_log_recvfd; pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN; if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) { if (errno == EINTR || errno == EAGAIN) continue; fatal_f("poll: %s", strerror(errno)); } if (pfd[1].revents) { /* * Drain all log messages before processing next * monitor request. */ monitor_read_log(pmonitor); continue; } if (pfd[0].revents) break; /* Continues below */ } if ((m = sshbuf_new()) == NULL) fatal_f("sshbuf_new"); mm_request_receive(pmonitor->m_sendfd, m); if ((r = sshbuf_get_u8(m, &type)) != 0) fatal_fr(r, "parse type"); debug3_f("checking request %d", type); while (ent->f != NULL) { if (ent->type == type) break; ent++; } if (ent->f != NULL) { if (!(ent->flags & MON_PERMIT)) fatal_f("unpermitted request %d", type); ret = (*ent->f)(ssh, pmonitor->m_sendfd, m); sshbuf_free(m); /* The child may use this request only once, disable it */ if (ent->flags & MON_ONCE) { debug2_f("%d used once, disabling now", type); ent->flags &= ~MON_PERMIT; } if (pent != NULL) *pent = ent; return ret; } fatal_f("unsupported request: %d", type); /* NOTREACHED */ return (-1); } /* allowed key state */ static int monitor_allowed_key(const u_char *blob, u_int bloblen) { /* make sure key is allowed */ if (key_blob == NULL || key_bloblen != bloblen || timingsafe_bcmp(key_blob, blob, key_bloblen)) return (0); return (1); } static void monitor_reset_key_state(void) { /* reset state */ free(key_blob); free(hostbased_cuser); free(hostbased_chost); sshauthopt_free(key_opts); key_blob = NULL; key_bloblen = 0; key_blobtype = MM_NOKEY; key_opts = NULL; hostbased_cuser = NULL; hostbased_chost = NULL; } #ifdef WITH_OPENSSL int mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m) { DH *dh; const BIGNUM *dh_p, *dh_g; int r; u_int min, want, max; if ((r = sshbuf_get_u32(m, &min)) != 0 || (r = sshbuf_get_u32(m, &want)) != 0 || (r = sshbuf_get_u32(m, &max)) != 0) fatal_fr(r, "parse"); debug3_f("got parameters: %d %d %d", min, want, max); /* We need to check here, too, in case the child got corrupted */ if (max < min || want < min || max < want) fatal_f("bad parameters: %d %d %d", min, want, max); sshbuf_reset(m); dh = choose_dh(min, want, max); if (dh == NULL) { if ((r = sshbuf_put_u8(m, 0)) != 0) fatal_fr(r, "assemble empty"); return (0); } else { /* Send first bignum */ DH_get0_pqg(dh, &dh_p, NULL, &dh_g); if ((r = sshbuf_put_u8(m, 1)) != 0 || (r = sshbuf_put_bignum2(m, dh_p)) != 0 || (r = sshbuf_put_bignum2(m, dh_g)) != 0) fatal_fr(r, "assemble"); DH_free(dh); } mm_request_send(sock, MONITOR_ANS_MODULI, m); return (0); } #endif int mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m) { extern int auth_sock; /* XXX move to state struct? */ struct sshkey *key; struct sshbuf *sigbuf = NULL; u_char *p = NULL, *signature = NULL; char *alg = NULL; size_t datlen, siglen, alglen; int r, is_proof = 0; u_int keyid, compat; const char proof_req[] = "hostkeys-prove-00@openssh.com"; debug3_f("entering"); if ((r = sshbuf_get_u32(m, &keyid)) != 0 || (r = sshbuf_get_string(m, &p, &datlen)) != 0 || (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 || (r = sshbuf_get_u32(m, &compat)) != 0) fatal_fr(r, "parse"); if (keyid > INT_MAX) fatal_f("invalid key ID"); /* * 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_f("bad data length: %zu", datlen); if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL) fatal_f("no hostkey for index %d", keyid); if ((sigbuf = sshbuf_new()) == NULL) fatal_f("sshbuf_new"); 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_fr(r, "assemble private key proof"); if (datlen != sshbuf_len(sigbuf) || memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0) fatal_f("bad data length: %zu, hostkey proof len %zu", datlen, sshbuf_len(sigbuf)); sshbuf_free(sigbuf); is_proof = 1; } /* save session id, it will be passed on the first call */ if (session_id2_len == 0) { session_id2_len = datlen; session_id2 = xmalloc(session_id2_len); memcpy(session_id2, p, session_id2_len); } if ((key = get_hostkey_by_index(keyid)) != NULL) { if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg, options.sk_provider, NULL, compat)) != 0) fatal_fr(r, "sign"); } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL && auth_sock > 0) { if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen, p, datlen, alg, compat)) != 0) fatal_fr(r, "agent sign"); } else fatal_f("no hostkey from index %d", keyid); debug3_f("%s %s signature len=%zu", alg, is_proof ? "hostkey proof" : "KEX", siglen); sshbuf_reset(m); if ((r = sshbuf_put_string(m, signature, siglen)) != 0) fatal_fr(r, "assemble"); 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); } #define PUTPW(b, id) \ do { \ if ((r = sshbuf_put_string(b, \ &pwent->id, sizeof(pwent->id))) != 0) \ fatal_fr(r, "assemble %s", #id); \ } while (0) /* Retrieves the password entry and also checks if the user is permitted */ int mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m) { struct passwd *pwent; int r, allowed = 0; u_int i; Authctxt *authctxt = ssh->authctxt; debug3_f("entering"); if (authctxt->attempt++ != 0) fatal_f("multiple attempts for getpwnam"); if ((r = sshbuf_get_cstring(m, &authctxt->user, NULL)) != 0) fatal_fr(r, "parse"); pwent = getpwnamallow(ssh, authctxt->user); setproctitle("%s [priv]", pwent ? authctxt->user : "unknown"); sshbuf_reset(m); if (pwent == NULL) { if ((r = sshbuf_put_u8(m, 0)) != 0) fatal_fr(r, "assemble fakepw"); authctxt->pw = fakepw(); goto out; } allowed = 1; authctxt->pw = pwent; authctxt->valid = 1; /* XXX send fake class/dir/shell, etc. */ if ((r = sshbuf_put_u8(m, 1)) != 0) fatal_fr(r, "assemble ok"); PUTPW(m, pw_uid); PUTPW(m, pw_gid); PUTPW(m, pw_change); PUTPW(m, pw_expire); if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 || (r = sshbuf_put_cstring(m, "*")) != 0 || (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 || (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 || (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 || (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0) fatal_fr(r, "assemble pw"); out: ssh_packet_set_log_preamble(ssh, "%suser %s", authctxt->valid ? "authenticating" : "invalid ", authctxt->user); if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0) fatal_fr(r, "assemble options"); #define M_CP_STROPT(x) do { \ if (options.x != NULL && \ (r = sshbuf_put_cstring(m, options.x)) != 0) \ fatal_fr(r, "assemble %s", #x); \ } while (0) #define M_CP_STRARRAYOPT(x, nx) do { \ for (i = 0; i < options.nx; i++) { \ if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \ fatal_fr(r, "assemble %s", #x); \ } \ } 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 its packet_disconnect(), but it must not allow any * authentication to succeed. */ debug_f("no valid authentication method lists"); } debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed); mm_request_send(sock, MONITOR_ANS_PWNAM, m); /* Allow service/style information on the auth context */ monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); #ifdef USE_PAM if (options.use_pam) monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1); #endif return (0); } int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m) { char *banner; int r; sshbuf_reset(m); banner = auth2_read_banner(); if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0) fatal_fr(r, "assemble"); mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m); free(banner); return (0); } int mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m) { int r; Authctxt *authctxt = ssh->authctxt; monitor_permit_authentications(1); if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 || (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0) fatal_fr(r, "parse"); debug3_f("service=%s, style=%s", authctxt->service, authctxt->style); if (strlen(authctxt->style) == 0) { free(authctxt->style); authctxt->style = NULL; } return (0); } int mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m) { static int call_count; char *passwd; int r, authenticated; size_t plen; if (!options.password_authentication) fatal_f("password authentication not enabled"); if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0) fatal_fr(r, "parse"); /* Only authenticate if the context is valid */ authenticated = options.password_authentication && auth_password(ssh, passwd); freezero(passwd, plen); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, authenticated)) != 0) fatal_fr(r, "assemble"); debug3_f("sending result %d", authenticated); mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m); call_count++; if (plen == 0 && call_count == 1) auth_method = "none"; else auth_method = "password"; /* Causes monitor loop to terminate if authenticated */ return (authenticated); } #ifdef BSD_AUTH int mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m) { char *name, *infotxt; u_int numprompts, *echo_on, success; char **prompts; int r; if (!options.kbd_interactive_authentication) fatal_f("kbd-int authentication not enabled"); success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, &prompts, &echo_on) < 0 ? 0 : 1; sshbuf_reset(m); if ((r = sshbuf_put_u32(m, success)) != 0) fatal_fr(r, "assemble"); if (success) { if ((r = sshbuf_put_cstring(m, prompts[0])) != 0) fatal_fr(r, "assemble prompt"); } debug3_f("sending challenge success: %u", success); mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m); if (success) { free(name); free(infotxt); free(prompts); free(echo_on); } return (0); } int mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m) { char *response; int r, authok; if (!options.kbd_interactive_authentication) fatal_f("kbd-int authentication not enabled"); if (authctxt->as == NULL) fatal_f("no bsd auth session"); if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0) fatal_fr(r, "parse"); authok = options.kbd_interactive_authentication && auth_userresponse(authctxt->as, response, 0); authctxt->as = NULL; debug3_f("<%s> = <%d>", response, authok); free(response); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, authok)) != 0) fatal_fr(r, "assemble"); debug3_f("sending authenticated: %d", authok); mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m); auth_method = "keyboard-interactive"; auth_submethod = "bsdauth"; return (authok != 0); } #endif #ifdef SKEY int mm_answer_skeyquery(int sock, struct sshbuf *m) { struct skey skey; char challenge[1024]; u_int success; success = skeychallenge(&skey, authctxt->user, challenge, sizeof(challenge)) < 0 ? 0 : 1; sshbuf_reset(m); sshbuf_put_int(m, success); if (success) sshbuf_put_cstring(m, challenge); debug3("%s: sending challenge success: %u", __func__, success); mm_request_send(sock, MONITOR_ANS_SKEYQUERY, m); return (0); } int mm_answer_skeyrespond(int sock, struct sshbuf *m) { char *response; int authok; int r; if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); authok = (options.kbd_interactive_authentication && authctxt->valid && skey_haskey(authctxt->pw->pw_name) == 0 && skey_passcheck(authctxt->pw->pw_name, response) != -1); free(response); sshbuf_reset(m); sshbuf_put_int(m, authok); debug3("%s: sending authenticated: %d", __func__, authok); mm_request_send(sock, MONITOR_ANS_SKEYRESPOND, m); auth_method = "skey"; auth_submethod = "bsdauth"; return (authok != 0); } #endif #ifdef USE_PAM int mm_answer_pam_start(struct ssh *ssh, int sock, struct sshbuf *m) { if (!options.use_pam) fatal("UsePAM not set, but ended up in %s anyway", __func__); start_pam(ssh); monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1); return (0); } int mm_answer_pam_account(struct ssh *ssh, int sock, struct sshbuf *m) { u_int ret; if (!options.use_pam) fatal("UsePAM not set, but ended up in %s anyway", __func__); ret = do_pam_account(); sshbuf_put_u32(m, ret); sshbuf_put_string(m, sshbuf_ptr(loginmsg), sshbuf_len(loginmsg)); mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m); return (ret); } static void *sshpam_ctxt, *sshpam_authok; extern KbdintDevice sshpam_device; int mm_answer_pam_init_ctx(struct ssh *ssh, int sock, struct sshbuf *m) { debug3("%s", __func__); sshpam_ctxt = (sshpam_device.init_ctx)(ssh->authctxt); sshpam_authok = NULL; sshbuf_reset(m); if (sshpam_ctxt != NULL) { monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1); sshbuf_put_u32(m, 1); } else { sshbuf_put_u32(m, 0); } mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m); return (0); } int mm_answer_pam_query(struct ssh *ssh, int sock, struct sshbuf *m) { char *name, *info, **prompts; u_int i, num, *echo_on; int ret; debug3("%s", __func__); sshpam_authok = NULL; ret = (sshpam_device.query)(sshpam_ctxt, &name, &info, &num, &prompts, &echo_on); if (ret == 0 && num == 0) sshpam_authok = sshpam_ctxt; if (num > 1 || name == NULL || info == NULL) ret = -1; sshbuf_reset(m); sshbuf_put_u32(m, ret); sshbuf_put_cstring(m, name); free(name); sshbuf_put_cstring(m, info); free(info); sshbuf_put_u32(m, num); for (i = 0; i < num; ++i) { sshbuf_put_cstring(m, prompts[i]); free(prompts[i]); sshbuf_put_u32(m, echo_on[i]); } if (prompts != NULL) free(prompts); if (echo_on != NULL) free(echo_on); auth_method = "keyboard-interactive/pam"; mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m); return (0); } int mm_answer_pam_respond(struct ssh *ssh, int sock, struct sshbuf *m) { char **resp; u_int i, num; int ret, r; debug3("%s", __func__); sshpam_authok = NULL; if ((r = sshbuf_get_u32(m, &num)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); if (num > 0) { resp = xmalloc(num * sizeof(char *)); for (i = 0; i < num; ++i) if ((r = sshbuf_get_cstring(m, &resp[i], NULL)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); ret = (sshpam_device.respond)(sshpam_ctxt, num, resp); for (i = 0; i < num; ++i) free(resp[i]); free(resp); } else { ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL); } sshbuf_reset(m); sshbuf_put_u32(m, ret); mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m); auth_method = "keyboard-interactive/pam"; if (ret == 0) sshpam_authok = sshpam_ctxt; return (0); } int mm_answer_pam_free_ctx(struct ssh *ssh, int sock, struct sshbuf *m) { int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt; debug3("%s", __func__); (sshpam_device.free_ctx)(sshpam_ctxt); sshpam_ctxt = sshpam_authok = NULL; sshbuf_reset(m); mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m); auth_method = "keyboard-interactive/pam"; return r; } #endif /* * Check that the key type appears in the supplied pattern list, ignoring * mismatches in the signature algorithm. (Signature algorithm checks are * performed in the unprivileged authentication code). * Returns 1 on success, 0 otherwise. */ static int key_base_type_match(const char *method, const struct sshkey *key, const char *list) { char *s, *l, *ol = xstrdup(list); int found = 0; l = ol; for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) { if (sshkey_type_from_name(s) == key->type) { found = 1; break; } } if (!found) { error("%s key type %s is not in permitted list %s", method, sshkey_ssh_name(key), list); } free(ol); return found; } int mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m) { struct sshkey *key = NULL; char *cuser, *chost; u_int pubkey_auth_attempt; u_int type = 0; int r, allowed = 0; struct sshauthopt *opts = NULL; Authctxt *authctxt = ssh->authctxt; debug3_f("entering"); if ((r = sshbuf_get_u32(m, &type)) != 0 || (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 || (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || (r = sshkey_froms(m, &key)) != 0 || (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0) fatal_fr(r, "parse"); if (key != NULL && authctxt->valid) { switch (type) { case MM_USERKEY: auth_method = "publickey"; if (!options.pubkey_authentication) break; if (auth2_key_already_used(authctxt, key)) break; if (!key_base_type_match(auth_method, key, options.pubkey_accepted_algos)) break; allowed = user_key_allowed(ssh, authctxt->pw, key, pubkey_auth_attempt, &opts); break; case MM_HOSTKEY: auth_method = "hostbased"; if (!options.hostbased_authentication) break; if (auth2_key_already_used(authctxt, key)) break; if (!key_base_type_match(auth_method, key, options.hostbased_accepted_algos)) break; allowed = hostbased_key_allowed(ssh, authctxt->pw, cuser, chost, key); auth2_record_info(authctxt, "client user \"%.100s\", client host \"%.100s\"", cuser, chost); break; default: fatal_f("unknown key type %u", type); break; } } debug3_f("%s authentication%s: %s key is %s", auth_method, pubkey_auth_attempt ? "" : " test", (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key), allowed ? "allowed" : "not allowed"); auth2_record_key(authctxt, 0, key); /* clear temporarily storage (used by verify) */ monitor_reset_key_state(); if (allowed) { /* Save temporarily for comparison in verify */ if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0) fatal_fr(r, "sshkey_to_blob"); key_blobtype = type; key_opts = opts; hostbased_cuser = cuser; hostbased_chost = chost; } else { /* Log failed attempt */ auth_log(ssh, 0, 0, auth_method, NULL); pfilter_notify(1); free(cuser); free(chost); } sshkey_free(key); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, allowed)) != 0) fatal_fr(r, "assemble"); if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0) fatal_fr(r, "sshauthopt_serialise"); mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); if (!allowed) sshauthopt_free(opts); return (0); } static int monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen) { struct sshbuf *b; struct sshkey *hostkey = NULL; const u_char *p; char *userstyle, *cp; size_t len; u_char type; int hostbound = 0, r, fail = 0; Authctxt *authctxt = ssh->authctxt; if ((b = sshbuf_from(data, datalen)) == NULL) fatal_f("sshbuf_from"); if (ssh->compat & SSH_OLD_SESSIONID) { p = sshbuf_ptr(b); len = sshbuf_len(b); if ((session_id2 == NULL) || (len < session_id2_len) || (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) fail++; if ((r = sshbuf_consume(b, session_id2_len)) != 0) fatal_fr(r, "consume"); } else { if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) fatal_fr(r, "parse sessionid"); if ((session_id2 == NULL) || (len != session_id2_len) || (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) fail++; } if ((r = sshbuf_get_u8(b, &type)) != 0) fatal_fr(r, "parse type"); if (type != SSH2_MSG_USERAUTH_REQUEST) fail++; if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) fatal_fr(r, "parse userstyle"); xasprintf(&userstyle, "%s%s%s", authctxt->user, authctxt->style ? ":" : "", authctxt->style ? authctxt->style : ""); if (strcmp(userstyle, cp) != 0) { logit("wrong user name passed to monitor: " "expected %s != %.100s", userstyle, cp); fail++; } free(userstyle); free(cp); if ((r = sshbuf_skip_string(b)) != 0 || /* service */ (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) fatal_fr(r, "parse method"); if (strcmp("publickey", cp) != 0) { if (strcmp("publickey-hostbound-v00@openssh.com", cp) == 0) hostbound = 1; else fail++; } free(cp); if ((r = sshbuf_get_u8(b, &type)) != 0) fatal_fr(r, "parse pktype"); if (type == 0) fail++; if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ (r = sshbuf_skip_string(b)) != 0 || /* pkblob */ (hostbound && (r = sshkey_froms(b, &hostkey)) != 0)) fatal_fr(r, "parse pk"); if (sshbuf_len(b) != 0) fail++; sshbuf_free(b); if (hostkey != NULL) { /* * Ensure this is actually one of our hostkeys; unfortunately * can't check ssh->kex->initial_hostkey directly at this point * as packet state has not yet been exported to monitor. */ if (get_hostkey_index(hostkey, 1, ssh) == -1) fatal_f("hostbound hostkey does not match"); sshkey_free(hostkey); } return (fail == 0); } static int monitor_valid_hostbasedblob(struct ssh *ssh, const u_char *data, u_int datalen, const char *cuser, const char *chost) { struct sshbuf *b; const u_char *p; char *cp, *userstyle; size_t len; int r, fail = 0; u_char type; Authctxt *authctxt = ssh->authctxt; if ((b = sshbuf_from(data, datalen)) == NULL) fatal_f("sshbuf_new"); if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) fatal_fr(r, "parse sessionid"); if ((session_id2 == NULL) || (len != session_id2_len) || (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) fail++; if ((r = sshbuf_get_u8(b, &type)) != 0) fatal_fr(r, "parse type"); if (type != SSH2_MSG_USERAUTH_REQUEST) fail++; if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) fatal_fr(r, "parse userstyle"); xasprintf(&userstyle, "%s%s%s", authctxt->user, authctxt->style ? ":" : "", authctxt->style ? authctxt->style : ""); if (strcmp(userstyle, cp) != 0) { logit("wrong user name passed to monitor: " "expected %s != %.100s", userstyle, cp); fail++; } free(userstyle); free(cp); if ((r = sshbuf_skip_string(b)) != 0 || /* service */ (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) fatal_fr(r, "parse method"); if (strcmp(cp, "hostbased") != 0) fail++; free(cp); if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ (r = sshbuf_skip_string(b)) != 0) /* pkblob */ fatal_fr(r, "parse pk"); /* verify client host, strip trailing dot if necessary */ if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) fatal_fr(r, "parse host"); if (((len = strlen(cp)) > 0) && cp[len - 1] == '.') cp[len - 1] = '\0'; if (strcmp(cp, chost) != 0) fail++; free(cp); /* verify client user */ if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) fatal_fr(r, "parse ruser"); if (strcmp(cp, cuser) != 0) fail++; free(cp); if (sshbuf_len(b) != 0) fail++; sshbuf_free(b); return (fail == 0); } int mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m) { struct sshkey *key; const u_char *signature, *data, *blob; char *sigalg = NULL, *fp = NULL; size_t signaturelen, datalen, bloblen; int r, ret, req_presence = 0, req_verify = 0, valid_data = 0; int encoded_ret; struct sshkey_sig_details *sig_details = NULL; Authctxt *authctxt = ssh->authctxt; if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 || (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 || (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 || (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0) fatal_fr(r, "parse"); if (hostbased_cuser == NULL || hostbased_chost == NULL || !monitor_allowed_key(blob, bloblen)) fatal_f("bad key, not previously allowed"); /* Empty signature algorithm means NULL. */ if (*sigalg == '\0') { free(sigalg); sigalg = NULL; } /* XXX use sshkey_froms here; need to change key_blob, etc. */ if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0) fatal_fr(r, "parse key"); switch (key_blobtype) { case MM_USERKEY: valid_data = monitor_valid_userblob(ssh, data, datalen); auth_method = "publickey"; break; case MM_HOSTKEY: valid_data = monitor_valid_hostbasedblob(ssh, data, datalen, hostbased_cuser, hostbased_chost); auth_method = "hostbased"; break; default: valid_data = 0; break; } if (!valid_data) fatal_f("bad %s signature data blob", key_blobtype == MM_USERKEY ? "userkey" : (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown")); if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) fatal_f("sshkey_fingerprint failed"); ret = sshkey_verify(key, signature, signaturelen, data, datalen, sigalg, ssh->compat, &sig_details); debug3_f("%s %s signature using %s %s%s%s", auth_method, sshkey_type(key), sigalg == NULL ? "default" : sigalg, (ret == 0) ? "verified" : "unverified", (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : ""); if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) { req_presence = (options.pubkey_auth_options & PUBKEYAUTH_TOUCH_REQUIRED) || !key_opts->no_require_user_presence; if (req_presence && (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) { error("public key %s %s signature for %s%s from %.128s " "port %d rejected: user presence " "(authenticator touch) requirement not met ", sshkey_type(key), fp, authctxt->valid ? "" : "invalid user ", authctxt->user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); ret = SSH_ERR_SIGNATURE_INVALID; } req_verify = (options.pubkey_auth_options & PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify; if (req_verify && (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) { error("public key %s %s signature for %s%s from %.128s " "port %d rejected: user verification requirement " "not met ", sshkey_type(key), fp, authctxt->valid ? "" : "invalid user ", authctxt->user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); ret = SSH_ERR_SIGNATURE_INVALID; } } auth2_record_key(authctxt, ret == 0, key); if (key_blobtype == MM_USERKEY) auth_activate_options(ssh, key_opts); monitor_reset_key_state(); sshbuf_reset(m); /* encode ret != 0 as positive integer, since we're sending u32 */ encoded_ret = (ret != 0); if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 || (r = sshbuf_put_u8(m, sig_details != NULL)) != 0) fatal_fr(r, "assemble"); if (sig_details != NULL) { if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 || (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0) fatal_fr(r, "assemble sk"); } sshkey_sig_details_free(sig_details); mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); free(sigalg); free(fp); sshkey_free(key); return ret == 0; } static void mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw) { socklen_t fromlen; struct sockaddr_storage from; /* * Get IP address of client. If the connection is not a socket, let * the address be 0.0.0.0. */ memset(&from, 0, sizeof(from)); fromlen = sizeof(from); if (ssh_packet_connection_is_on_socket(ssh)) { if (getpeername(ssh_packet_get_connection_in(ssh), (struct sockaddr *)&from, &fromlen) == -1) { debug("getpeername: %.100s", strerror(errno)); cleanup_exit(254); } } /* Record that there was a login on that tty from the remote host. */ record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid, session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), (struct sockaddr *)&from, fromlen); } static void mm_session_close(Session *s) { debug3_f("session %d pid %ld", s->self, (long)s->pid); if (s->ttyfd != -1) { debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd); session_pty_cleanup2(s); } session_unused(s->self); } int mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m) { extern struct monitor *pmonitor; Session *s; int r, res, fd0; Authctxt *authctxt = ssh->authctxt; debug3_f("entering"); sshbuf_reset(m); s = session_new(); if (s == NULL) goto error; s->authctxt = authctxt; s->pw = authctxt->pw; s->pid = pmonitor->m_pid; res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); if (res == 0) goto error; pty_setowner(authctxt->pw, s->tty); if ((r = sshbuf_put_u32(m, 1)) != 0 || (r = sshbuf_put_cstring(m, s->tty)) != 0) fatal_fr(r, "assemble"); /* We need to trick ttyslot */ if (dup2(s->ttyfd, 0) == -1) fatal_f("dup2"); mm_record_login(ssh, s, authctxt->pw); /* Now we can close the file descriptor again */ close(0); /* send messages generated by record_login */ if ((r = sshbuf_put_stringb(m, loginmsg)) != 0) fatal_fr(r, "assemble loginmsg"); sshbuf_reset(loginmsg); mm_request_send(sock, MONITOR_ANS_PTY, m); if (mm_send_fd(sock, s->ptyfd) == -1 || mm_send_fd(sock, s->ttyfd) == -1) fatal_f("send fds failed"); /* make sure nothing uses fd 0 */ if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1) fatal_f("open(/dev/null): %s", strerror(errno)); if (fd0 != 0) error_f("fd0 %d != 0", fd0); /* slave side of pty is not needed */ close(s->ttyfd); s->ttyfd = s->ptyfd; /* no need to dup() because nobody closes ptyfd */ s->ptymaster = s->ptyfd; debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd); return (0); error: if (s != NULL) mm_session_close(s); if ((r = sshbuf_put_u32(m, 0)) != 0) fatal_fr(r, "assemble 0"); mm_request_send(sock, MONITOR_ANS_PTY, m); return (0); } int mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m) { Session *s; char *tty; int r; debug3_f("entering"); if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0) fatal_fr(r, "parse tty"); if ((s = session_by_tty(tty)) != NULL) mm_session_close(s); sshbuf_reset(m); free(tty); return (0); } #ifdef KRB5 int mm_answer_krb5(struct ssh *ssh, int xsocket, struct sshbuf *m) { krb5_data tkt, reply; char *client_user; unsigned char *data; size_t len; int r; int success; Authctxt *authctxt = ssh->authctxt; /* use temporary var to avoid size issues on 64bit arch */ if ((r = sshbuf_get_string(m, &data, &len)) != 0) fatal("%s: buffer error: %s", __func__, ssh_err(r)); tkt.data = data; tkt.length = len; success = options.kerberos_authentication && authctxt->valid && auth_krb5(ssh, &tkt, &client_user, &reply); if (tkt.length) free(tkt.data); sshbuf_reset(m); sshbuf_put_u32(m, success); if (success) { sshbuf_put_cstring(m, client_user); sshbuf_put_string(m, reply.data, reply.length); if (client_user) free(client_user); if (reply.length) free(reply.data); } mm_request_send(xsocket, MONITOR_ANS_KRB5, m); auth_method = "kerberos"; return success; } #endif int mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req) { extern struct monitor *pmonitor; int res, status; debug3_f("tearing down sessions"); /* The child is terminating */ session_destroy_all(ssh, &mm_session_close); while (waitpid(pmonitor->m_pid, &status, 0) == -1) if (errno != EINTR) exit(1); res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; /* Terminate process */ exit(res); } void monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor) { ssh_clear_newkeys(ssh, MODE_IN); ssh_clear_newkeys(ssh, MODE_OUT); sshbuf_free(child_state); child_state = NULL; } void monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor) { struct kex *kex; int r; debug3_f("packet_set_state"); if ((r = ssh_packet_set_state(ssh, child_state)) != 0) fatal_fr(r, "packet_set_state"); sshbuf_free(child_state); child_state = NULL; if ((kex = ssh->kex) == NULL) fatal_f("internal error: ssh->kex == NULL"); if (session_id2_len != sshbuf_len(ssh->kex->session_id)) { fatal_f("incorrect session id length %zu (expected %u)", sshbuf_len(ssh->kex->session_id), session_id2_len); } if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2, session_id2_len) != 0) fatal_f("session ID mismatch"); /* XXX set callbacks */ #ifdef WITH_OPENSSL kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; kex->kex[KEX_ECDH_SHA2] = kex_gen_server; #endif kex->kex[KEX_C25519_SHA256] = kex_gen_server; kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; kex->load_host_public_key=&get_hostkey_public_by_type; kex->load_host_private_key=&get_hostkey_private_by_type; kex->host_key_index=&get_hostkey_index; kex->sign = sshd_hostkey_sign; } /* This function requires careful sanity checking */ void mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor) { debug3_f("Waiting for new keys"); if ((child_state = sshbuf_new()) == NULL) fatal_f("sshbuf_new failed"); mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, child_state); debug3_f("GOT new keys"); } /* 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_f("socketpair: %s", strerror(errno)); #ifdef SO_ZEROIZE if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno)); if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno)); #endif FD_CLOSEONEXEC(pair[0]); FD_CLOSEONEXEC(pair[1]); mon->m_recvfd = pair[0]; mon->m_sendfd = pair[1]; if (do_logfds) { if (pipe(pair) == -1) fatal_f("pipe: %s", strerror(errno)); FD_CLOSEONEXEC(pair[0]); FD_CLOSEONEXEC(pair[1]); mon->m_log_recvfd = pair[0]; mon->m_log_sendfd = pair[1]; } else mon->m_log_recvfd = mon->m_log_sendfd = -1; } #define MM_MEMSIZE 65536 struct monitor * monitor_init(void) { struct monitor *mon; mon = xcalloc(1, sizeof(*mon)); monitor_openfds(mon, 1); return mon; } void monitor_reinit(struct monitor *mon) { monitor_openfds(mon, 0); } #ifdef GSSAPI int mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m) { gss_OID_desc goid; OM_uint32 major; size_t len; u_char *p; int r; if (!options.gss_authentication) fatal_f("GSSAPI authentication not enabled"); if ((r = sshbuf_get_string(m, &p, &len)) != 0) fatal_fr(r, "parse"); goid.elements = p; goid.length = len; major = ssh_gssapi_server_ctx(&gsscontext, &goid); free(goid.elements); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, major)) != 0) fatal_fr(r, "assemble"); mm_request_send(sock, MONITOR_ANS_GSSSETUP, m); /* Now we have a context, enable the step */ monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1); return (0); } int mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) { gss_buffer_desc in; gss_buffer_desc out = GSS_C_EMPTY_BUFFER; OM_uint32 major, minor; OM_uint32 flags = 0; /* GSI needs this */ int r; if (!options.gss_authentication) fatal_f("GSSAPI authentication not enabled"); if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0) fatal_fr(r, "ssh_gssapi_get_buffer_desc"); major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); free(in.value); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, major)) != 0 || (r = sshbuf_put_string(m, out.value, out.length)) != 0 || (r = sshbuf_put_u32(m, flags)) != 0) fatal_fr(r, "assemble"); mm_request_send(sock, MONITOR_ANS_GSSSTEP, m); gss_release_buffer(&minor, &out); if (major == GSS_S_COMPLETE) { monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); } return (0); } int mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) { gss_buffer_desc gssbuf, mic; OM_uint32 ret; int r; if (!options.gss_authentication) fatal_f("GSSAPI authentication not enabled"); if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 || (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0) fatal_fr(r, "ssh_gssapi_get_buffer_desc"); ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); free(gssbuf.value); free(mic.value); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, ret)) != 0) fatal_fr(r, "assemble"); mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); if (!GSS_ERROR(ret)) monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); return (0); } int mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) { int r, authenticated; const char *displayname; Authctxt *authctxt = ssh->authctxt; if (!options.gss_authentication) fatal_f("GSSAPI authentication not enabled"); authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, authenticated)) != 0) fatal_fr(r, "assemble"); debug3_f("sending result %d", 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 */