/* * 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("$OpenBSD: monitor.c,v 1.32 2003/02/16 17:30:33 markus Exp $"); #include #ifdef SKEY #include #endif #include "ssh.h" #include "auth.h" #include "kex.h" #include "dh.h" #include "zlib.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 "servconf.h" #include "monitor.h" #include "monitor_mm.h" #include "monitor_wrap.h" #include "monitor_fdpass.h" #include "xmalloc.h" #include "misc.h" #include "buffer.h" #include "bufaux.h" #include "compat.h" #include "ssh2.h" #include "mpaux.h" /* Imports */ extern ServerOptions options; extern u_int utmp_len; extern Newkeys *current_keys[]; extern z_stream incoming_stream; extern z_stream outgoing_stream; extern u_char session_id[]; extern Buffer input, output; extern Buffer auth_debug; extern int auth_debug_init; /* State exported from the child */ struct { z_stream incoming; z_stream outgoing; u_char *keyin; u_int keyinlen; u_char *keyout; u_int keyoutlen; u_char *ivin; u_int ivinlen; u_char *ivout; u_int ivoutlen; u_char *ssh1key; u_int ssh1keylen; int ssh1cipher; int ssh1protoflags; u_char *input; u_int ilen; u_char *output; u_int olen; } child_state; /* Functions on the montior that answer unprivileged requests */ int mm_answer_moduli(int, Buffer *); int mm_answer_sign(int, Buffer *); int mm_answer_pwnamallow(int, Buffer *); int mm_answer_auth2_read_banner(int, Buffer *); int mm_answer_authserv(int, Buffer *); int mm_answer_authpassword(int, Buffer *); int mm_answer_bsdauthquery(int, Buffer *); int mm_answer_bsdauthrespond(int, Buffer *); int mm_answer_skeyquery(int, Buffer *); int mm_answer_skeyrespond(int, Buffer *); int mm_answer_keyallowed(int, Buffer *); int mm_answer_keyverify(int, Buffer *); int mm_answer_pty(int, Buffer *); int mm_answer_pty_cleanup(int, Buffer *); int mm_answer_term(int, Buffer *); int mm_answer_rsa_keyallowed(int, Buffer *); int mm_answer_rsa_challenge(int, Buffer *); int mm_answer_rsa_response(int, Buffer *); int mm_answer_sesskey(int, Buffer *); int mm_answer_sessid(int, Buffer *); #ifdef USE_PAM int mm_answer_pam_start(int, Buffer *); #endif #ifdef KRB4 int mm_answer_krb4(int, Buffer *); #endif #ifdef KRB5 int mm_answer_krb5(int, Buffer *); #endif static Authctxt *authctxt; static BIGNUM *ssh1_challenge = NULL; /* used for ssh1 rsa auth */ /* 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 int session_id2_len = 0; static u_char *session_id2 = NULL; 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_AUTH (MON_ISAUTH|MON_AUTHDECIDE) #define MON_PERMIT 0x1000 /* Request is permitted */ struct mon_table mon_dispatch_proto20[] = { {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, {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}, #endif #ifdef BSD_AUTH {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH,mm_answer_bsdauthrespond}, #endif #ifdef SKEY {MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery}, {MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond}, #endif {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, {0, 0, NULL} }; struct mon_table mon_dispatch_postauth20[] = { {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, {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_proto15[] = { {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, {MONITOR_REQ_SESSKEY, MON_ONCE, mm_answer_sesskey}, {MONITOR_REQ_SESSID, MON_ONCE, mm_answer_sessid}, {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, {MONITOR_REQ_RSAKEYALLOWED, MON_ISAUTH, mm_answer_rsa_keyallowed}, {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, {MONITOR_REQ_RSACHALLENGE, MON_ONCE, mm_answer_rsa_challenge}, {MONITOR_REQ_RSARESPONSE, MON_ONCE|MON_AUTHDECIDE, mm_answer_rsa_response}, #ifdef BSD_AUTH {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH,mm_answer_bsdauthrespond}, #endif #ifdef SKEY {MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery}, {MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond}, #endif #ifdef USE_PAM {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start}, #endif #ifdef KRB4 {MONITOR_REQ_KRB4, MON_ONCE|MON_AUTH, mm_answer_krb4}, #endif #ifdef KRB5 {MONITOR_REQ_KRB5, MON_ONCE|MON_AUTH, mm_answer_krb5}, #endif {0, 0, NULL} }; struct mon_table mon_dispatch_postauth15[] = { {MONITOR_REQ_PTY, MON_ONCE, mm_answer_pty}, {MONITOR_REQ_PTYCLEANUP, MON_ONCE, 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++; } } Authctxt * monitor_child_preauth(struct monitor *pmonitor) { struct mon_table *ent; int authenticated = 0; debug3("preauth child monitor started"); if (compat20) { mon_dispatch = mon_dispatch_proto20; /* Permit requests for moduli and signatures */ monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); } else { mon_dispatch = mon_dispatch_proto15; monitor_permit(mon_dispatch, MONITOR_REQ_SESSKEY, 1); } authctxt = authctxt_new(); /* The first few requests do not require asynchronous access */ while (!authenticated) { authenticated = monitor_read(pmonitor, mon_dispatch, &ent); if (authenticated) { if (!(ent->flags & MON_AUTHDECIDE)) fatal("%s: unexpected authentication from %d", __func__, ent->type); if (authctxt->pw->pw_uid == 0 && !auth_root_allowed(auth_method)) authenticated = 0; #ifdef USE_PAM if (!do_pam_account(authctxt->pw->pw_name, NULL)) authenticated = 0; #endif } if (ent->flags & MON_AUTHDECIDE) { auth_log(authctxt, authenticated, auth_method, compat20 ? " ssh2" : ""); if (!authenticated) authctxt->failures++; } } if (!authctxt->valid) fatal("%s: authenticated invalid user", __func__); debug("%s: %s has been authenticated by privileged process", __func__, authctxt->user); mm_get_keystate(pmonitor); return (authctxt); } void monitor_child_postauth(struct monitor *pmonitor) { if (compat20) { mon_dispatch = mon_dispatch_postauth20; /* Permit requests for moduli and signatures */ monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); } else { mon_dispatch = mon_dispatch_postauth15; monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); } if (!no_pty_flag) { monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); } for (;;) monitor_read(pmonitor, mon_dispatch, NULL); } void monitor_sync(struct monitor *pmonitor) { if (options.compression) { /* The member allocation is not visible, so sync it */ mm_share_sync(&pmonitor->m_zlib, &pmonitor->m_zback); } } int monitor_read(struct monitor *pmonitor, struct mon_table *ent, struct mon_table **pent) { Buffer m; int ret; u_char type; 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 || memcmp(key_blob, blob, key_bloblen)) return (0); return (1); } static void monitor_reset_key_state(void) { /* reset state */ if (key_blob != NULL) xfree(key_blob); if (hostbased_cuser != NULL) xfree(hostbased_cuser); if (hostbased_chost != NULL) xfree(hostbased_chost); key_blob = NULL; key_bloblen = 0; key_blobtype = MM_NOKEY; hostbased_cuser = NULL; hostbased_chost = NULL; } int mm_answer_moduli(int socket, 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(socket, MONITOR_ANS_MODULI, m); return (0); } int mm_answer_sign(int socket, Buffer *m) { Key *key; u_char *p; u_char *signature; u_int siglen, datlen; int keyid; debug3("%s", __func__); keyid = buffer_get_int(m); p = buffer_get_string(m, &datlen); if (datlen != 20) fatal("%s: data length incorrect: %u", __func__, datlen); /* 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) fatal("%s: no hostkey from index %d", __func__, keyid); if (key_sign(key, &signature, &siglen, p, datlen) < 0) fatal("%s: key_sign failed", __func__); debug3("%s: signature %p(%u)", __func__, signature, siglen); buffer_clear(m); buffer_put_string(m, signature, siglen); xfree(p); xfree(signature); mm_request_send(socket, 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 socket, Buffer *m) { char *login; struct passwd *pwent; int allowed = 0; debug3("%s", __func__); if (authctxt->attempt++ != 0) fatal("%s: multiple attempts for getpwnam", __func__); login = buffer_get_string(m, NULL); pwent = getpwnamallow(login); authctxt->user = xstrdup(login); setproctitle("%s [priv]", pwent ? login : "unknown"); xfree(login); buffer_clear(m); if (pwent == NULL) { buffer_put_char(m, 0); 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); #ifdef HAVE_PW_CLASS_IN_PASSWD buffer_put_cstring(m, pwent->pw_class); #endif buffer_put_cstring(m, pwent->pw_dir); buffer_put_cstring(m, pwent->pw_shell); out: debug3("%s: sending MONITOR_ANS_PWNAM: %d", __func__, allowed); mm_request_send(socket, MONITOR_ANS_PWNAM, m); /* For SSHv1 allow authentication now */ if (!compat20) monitor_permit_authentications(1); else { /* Allow service/style information on the auth context */ monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); } #ifdef USE_PAM monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1); #endif return (0); } int mm_answer_auth2_read_banner(int socket, Buffer *m) { char *banner; buffer_clear(m); banner = auth2_read_banner(); buffer_put_cstring(m, banner != NULL ? banner : ""); mm_request_send(socket, MONITOR_ANS_AUTH2_READ_BANNER, m); if (banner != NULL) xfree(banner); return (0); } int mm_answer_authserv(int socket, 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) { xfree(authctxt->style); authctxt->style = NULL; } return (0); } int mm_answer_authpassword(int socket, Buffer *m) { static int call_count; char *passwd; int authenticated; u_int plen; passwd = buffer_get_string(m, &plen); /* Only authenticate if the context is valid */ authenticated = options.password_authentication && authctxt->valid && auth_password(authctxt, passwd); memset(passwd, 0, strlen(passwd)); xfree(passwd); buffer_clear(m); buffer_put_int(m, authenticated); debug3("%s: sending result %d", __func__, authenticated); mm_request_send(socket, MONITOR_ANS_AUTHPASSWORD, m); call_count++; if (plen == 0 && call_count == 1) auth_method = "none"; else auth_method = "password"; /* Causes monitor loop to terminate if authenticated */ return (authenticated); } #ifdef BSD_AUTH int mm_answer_bsdauthquery(int socket, Buffer *m) { char *name, *infotxt; u_int numprompts; u_int *echo_on; char **prompts; u_int success; success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, &prompts, &echo_on) < 0 ? 0 : 1; buffer_clear(m); buffer_put_int(m, success); if (success) buffer_put_cstring(m, prompts[0]); debug3("%s: sending challenge success: %u", __func__, success); mm_request_send(socket, MONITOR_ANS_BSDAUTHQUERY, m); if (success) { xfree(name); xfree(infotxt); xfree(prompts); xfree(echo_on); } return (0); } int mm_answer_bsdauthrespond(int socket, Buffer *m) { char *response; int authok; if (authctxt->as == 0) fatal("%s: no bsd auth session", __func__); response = buffer_get_string(m, NULL); authok = options.challenge_response_authentication && auth_userresponse(authctxt->as, response, 0); authctxt->as = NULL; debug3("%s: <%s> = <%d>", __func__, response, authok); xfree(response); buffer_clear(m); buffer_put_int(m, authok); debug3("%s: sending authenticated: %d", __func__, authok); mm_request_send(socket, MONITOR_ANS_BSDAUTHRESPOND, m); auth_method = "bsdauth"; return (authok != 0); } #endif #ifdef SKEY int mm_answer_skeyquery(int socket, Buffer *m) { struct skey skey; char challenge[1024]; u_int success; success = skeychallenge(&skey, authctxt->user, challenge) < 0 ? 0 : 1; buffer_clear(m); buffer_put_int(m, success); if (success) buffer_put_cstring(m, challenge); debug3("%s: sending challenge success: %u", __func__, success); mm_request_send(socket, MONITOR_ANS_SKEYQUERY, m); return (0); } int mm_answer_skeyrespond(int socket, Buffer *m) { char *response; int authok; response = buffer_get_string(m, NULL); authok = (options.challenge_response_authentication && authctxt->valid && skey_haskey(authctxt->pw->pw_name) == 0 && skey_passcheck(authctxt->pw->pw_name, response) != -1); xfree(response); buffer_clear(m); buffer_put_int(m, authok); debug3("%s: sending authenticated: %d", __func__, authok); mm_request_send(socket, MONITOR_ANS_SKEYRESPOND, m); auth_method = "skey"; return (authok != 0); } #endif #ifdef USE_PAM int mm_answer_pam_start(int socket, Buffer *m) { char *user; user = buffer_get_string(m, NULL); start_pam(user); xfree(user); return (0); } #endif static void mm_append_debug(Buffer *m) { if (auth_debug_init && buffer_len(&auth_debug)) { debug3("%s: Appending debug messages for child", __func__); buffer_append(m, buffer_ptr(&auth_debug), buffer_len(&auth_debug)); buffer_clear(&auth_debug); } } int mm_answer_keyallowed(int socket, Buffer *m) { Key *key; char *cuser, *chost; u_char *blob; u_int bloblen; 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); key = key_from_blob(blob, bloblen); if ((compat20 && type == MM_RSAHOSTKEY) || (!compat20 && type != MM_RSAHOSTKEY)) fatal("%s: key type and protocol mismatch", __func__); debug3("%s: key_from_blob: %p", __func__, key); if (key != NULL && authctxt->pw != NULL) { switch(type) { case MM_USERKEY: allowed = options.pubkey_authentication && user_key_allowed(authctxt->pw, key); break; case MM_HOSTKEY: allowed = options.hostbased_authentication && hostbased_key_allowed(authctxt->pw, cuser, chost, key); break; case MM_RSAHOSTKEY: key->type = KEY_RSA1; /* XXX */ allowed = options.rhosts_rsa_authentication && auth_rhosts_rsa_key_allowed(authctxt->pw, cuser, chost, key); break; default: fatal("%s: unknown key type %d", __func__, type); break; } key_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; } debug3("%s: key %p is %s", __func__, key, allowed ? "allowed" : "disallowed"); buffer_clear(m); buffer_put_int(m, allowed); buffer_put_int(m, forced_command != NULL); mm_append_debug(m); mm_request_send(socket, MONITOR_ANS_KEYALLOWED, m); if (type == MM_RSAHOSTKEY) monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed); return (0); } static int monitor_valid_userblob(u_char *data, u_int datalen) { Buffer b; char *p; 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) || (memcmp(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) || (memcmp(p, session_id2, session_id2_len) != 0)) fail++; xfree(p); } if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) fail++; p = buffer_get_string(&b, NULL); if (strcmp(authctxt->user, p) != 0) { log("wrong user name passed to monitor: expected %s != %.100s", authctxt->user, p); fail++; } xfree(p); buffer_skip_string(&b); if (datafellows & SSH_BUG_PKAUTH) { if (!buffer_get_char(&b)) fail++; } else { p = buffer_get_string(&b, NULL); if (strcmp("publickey", p) != 0) fail++; xfree(p); 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; 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) || (memcmp(p, session_id2, session_id2_len) != 0)) fail++; xfree(p); if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) fail++; p = buffer_get_string(&b, NULL); if (strcmp(authctxt->user, p) != 0) { log("wrong user name passed to monitor: expected %s != %.100s", authctxt->user, p); fail++; } xfree(p); buffer_skip_string(&b); /* service */ p = buffer_get_string(&b, NULL); if (strcmp(p, "hostbased") != 0) fail++; xfree(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++; xfree(p); /* verify client user */ p = buffer_get_string(&b, NULL); if (strcmp(p, cuser) != 0) fail++; xfree(p); if (buffer_len(&b) != 0) fail++; buffer_free(&b); return (fail == 0); } int mm_answer_keyverify(int socket, Buffer *m) { Key *key; u_char *signature, *data, *blob; u_int signaturelen, datalen, bloblen; int verified = 0; int valid_data = 0; blob = buffer_get_string(m, &bloblen); signature = buffer_get_string(m, &signaturelen); data = buffer_get_string(m, &datalen); if (hostbased_cuser == NULL || hostbased_chost == NULL || !monitor_allowed_key(blob, bloblen)) fatal("%s: bad key, not previously allowed", __func__); key = key_from_blob(blob, bloblen); if (key == NULL) fatal("%s: bad public key blob", __func__); switch (key_blobtype) { case MM_USERKEY: valid_data = monitor_valid_userblob(data, datalen); break; case MM_HOSTKEY: valid_data = monitor_valid_hostbasedblob(data, datalen, hostbased_cuser, hostbased_chost); break; default: valid_data = 0; break; } if (!valid_data) fatal("%s: bad signature data blob", __func__); verified = key_verify(key, signature, signaturelen, data, datalen); debug3("%s: key %p signature %s", __func__, key, verified ? "verified" : "unverified"); key_free(key); xfree(blob); xfree(signature); xfree(data); auth_method = key_blobtype == MM_USERKEY ? "publickey" : "hostbased"; monitor_reset_key_state(); buffer_clear(m); buffer_put_int(m, verified); mm_request_send(socket, MONITOR_ANS_KEYVERIFY, m); return (verified); } static void mm_record_login(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 (packet_connection_is_on_socket()) { if (getpeername(packet_get_connection_in(), (struct sockaddr *) & from, &fromlen) < 0) { debug("getpeername: %.100s", strerror(errno)); fatal_cleanup(); } } /* 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, get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping), (struct sockaddr *)&from, fromlen); } static void mm_session_close(Session *s) { debug3("%s: session %d pid %d", __func__, s->self, s->pid); if (s->ttyfd != -1) { debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ptyfd); fatal_remove_cleanup(session_pty_cleanup2, (void *)s); session_pty_cleanup2(s); } s->used = 0; } int mm_answer_pty(int socket, 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; fatal_add_cleanup(session_pty_cleanup2, (void *)s); pty_setowner(authctxt->pw, s->tty); buffer_put_int(m, 1); buffer_put_cstring(m, s->tty); mm_request_send(socket, MONITOR_ANS_PTY, m); mm_send_fd(socket, s->ptyfd); mm_send_fd(socket, s->ttyfd); /* 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); /* 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(socket, MONITOR_ANS_PTY, m); return (0); } int mm_answer_pty_cleanup(int socket, 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); xfree(tty); return (0); } int mm_answer_sesskey(int socket, Buffer *m) { BIGNUM *p; int rsafail; /* Turn off permissions */ monitor_permit(mon_dispatch, MONITOR_REQ_SESSKEY, 1); if ((p = BN_new()) == NULL) fatal("%s: BN_new", __func__); buffer_get_bignum2(m, p); rsafail = ssh1_session_key(p); buffer_clear(m); buffer_put_int(m, rsafail); buffer_put_bignum2(m, p); BN_clear_free(p); mm_request_send(socket, MONITOR_ANS_SESSKEY, m); /* Turn on permissions for sessid passing */ monitor_permit(mon_dispatch, MONITOR_REQ_SESSID, 1); return (0); } int mm_answer_sessid(int socket, Buffer *m) { int i; debug3("%s entering", __func__); if (buffer_len(m) != 16) fatal("%s: bad ssh1 session id", __func__); for (i = 0; i < 16; i++) session_id[i] = buffer_get_char(m); /* Turn on permissions for getpwnam */ monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); return (0); } int mm_answer_rsa_keyallowed(int socket, Buffer *m) { BIGNUM *client_n; Key *key = NULL; u_char *blob = NULL; u_int blen = 0; int allowed = 0; debug3("%s entering", __func__); if (options.rsa_authentication && authctxt->valid) { if ((client_n = BN_new()) == NULL) fatal("%s: BN_new", __func__); buffer_get_bignum2(m, client_n); allowed = auth_rsa_key_allowed(authctxt->pw, client_n, &key); BN_clear_free(client_n); } buffer_clear(m); buffer_put_int(m, allowed); buffer_put_int(m, forced_command != NULL); /* clear temporarily storage (used by generate challenge) */ monitor_reset_key_state(); if (allowed && key != NULL) { key->type = KEY_RSA; /* cheat for key_to_blob */ if (key_to_blob(key, &blob, &blen) == 0) fatal("%s: key_to_blob failed", __func__); buffer_put_string(m, blob, blen); /* Save temporarily for comparison in verify */ key_blob = blob; key_bloblen = blen; key_blobtype = MM_RSAUSERKEY; key_free(key); } mm_append_debug(m); mm_request_send(socket, MONITOR_ANS_RSAKEYALLOWED, m); monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed); monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 0); return (0); } int mm_answer_rsa_challenge(int socket, Buffer *m) { Key *key = NULL; u_char *blob; u_int blen; debug3("%s entering", __func__); if (!authctxt->valid) fatal("%s: authctxt not valid", __func__); blob = buffer_get_string(m, &blen); if (!monitor_allowed_key(blob, blen)) fatal("%s: bad key, not previously allowed", __func__); if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY) fatal("%s: key type mismatch", __func__); if ((key = key_from_blob(blob, blen)) == NULL) fatal("%s: received bad key", __func__); if (ssh1_challenge) BN_clear_free(ssh1_challenge); ssh1_challenge = auth_rsa_generate_challenge(key); buffer_clear(m); buffer_put_bignum2(m, ssh1_challenge); debug3("%s sending reply", __func__); mm_request_send(socket, MONITOR_ANS_RSACHALLENGE, m); monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 1); return (0); } int mm_answer_rsa_response(int socket, Buffer *m) { Key *key = NULL; u_char *blob, *response; u_int blen, len; int success; debug3("%s entering", __func__); if (!authctxt->valid) fatal("%s: authctxt not valid", __func__); if (ssh1_challenge == NULL) fatal("%s: no ssh1_challenge", __func__); blob = buffer_get_string(m, &blen); if (!monitor_allowed_key(blob, blen)) fatal("%s: bad key, not previously allowed", __func__); if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY) fatal("%s: key type mismatch: %d", __func__, key_blobtype); if ((key = key_from_blob(blob, blen)) == NULL) fatal("%s: received bad key", __func__); response = buffer_get_string(m, &len); if (len != 16) fatal("%s: received bad response to challenge", __func__); success = auth_rsa_verify_response(key, ssh1_challenge, response); key_free(key); xfree(response); auth_method = key_blobtype == MM_RSAUSERKEY ? "rsa" : "rhosts-rsa"; /* reset state */ BN_clear_free(ssh1_challenge); ssh1_challenge = NULL; monitor_reset_key_state(); buffer_clear(m); buffer_put_int(m, success); mm_request_send(socket, MONITOR_ANS_RSARESPONSE, m); return (success); } #ifdef KRB4 int mm_answer_krb4(int socket, Buffer *m) { KTEXT_ST auth, reply; char *client, *p; int success; u_int alen; reply.length = auth.length = 0; p = buffer_get_string(m, &alen); if (alen >= MAX_KTXT_LEN) fatal("%s: auth too large", __func__); memcpy(auth.dat, p, alen); auth.length = alen; memset(p, 0, alen); xfree(p); success = options.kerberos_authentication && authctxt->valid && auth_krb4(authctxt, &auth, &client, &reply); memset(auth.dat, 0, alen); buffer_clear(m); buffer_put_int(m, success); if (success) { buffer_put_cstring(m, client); buffer_put_string(m, reply.dat, reply.length); if (client) xfree(client); if (reply.length) memset(reply.dat, 0, reply.length); } debug3("%s: sending result %d", __func__, success); mm_request_send(socket, MONITOR_ANS_KRB4, m); auth_method = "kerberos"; /* Causes monitor loop to terminate if authenticated */ return (success); } #endif #ifdef KRB5 int mm_answer_krb5(int socket, Buffer *m) { krb5_data tkt, reply; char *client_user; u_int len; int success; /* use temporary var to avoid size issues on 64bit arch */ tkt.data = buffer_get_string(m, &len); tkt.length = len; success = options.kerberos_authentication && authctxt->valid && auth_krb5(authctxt, &tkt, &client_user, &reply); if (tkt.length) xfree(tkt.data); buffer_clear(m); buffer_put_int(m, success); if (success) { buffer_put_cstring(m, client_user); buffer_put_string(m, reply.data, reply.length); if (client_user) xfree(client_user); if (reply.length) xfree(reply.data); } mm_request_send(socket, MONITOR_ANS_KRB5, m); return success; } #endif int mm_answer_term(int socket, 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_apply_keystate(struct monitor *pmonitor) { if (compat20) { set_newkeys(MODE_IN); set_newkeys(MODE_OUT); } else { packet_set_protocol_flags(child_state.ssh1protoflags); packet_set_encryption_key(child_state.ssh1key, child_state.ssh1keylen, child_state.ssh1cipher); xfree(child_state.ssh1key); } /* for rc4 and other stateful ciphers */ packet_set_keycontext(MODE_OUT, child_state.keyout); xfree(child_state.keyout); packet_set_keycontext(MODE_IN, child_state.keyin); xfree(child_state.keyin); if (!compat20) { packet_set_iv(MODE_OUT, child_state.ivout); xfree(child_state.ivout); packet_set_iv(MODE_IN, child_state.ivin); xfree(child_state.ivin); } memcpy(&incoming_stream, &child_state.incoming, sizeof(incoming_stream)); memcpy(&outgoing_stream, &child_state.outgoing, sizeof(outgoing_stream)); /* Update with new address */ if (options.compression) mm_init_compression(pmonitor->m_zlib); /* Network I/O buffers */ /* XXX inefficient for large buffers, need: buffer_init_from_string */ buffer_clear(&input); buffer_append(&input, child_state.input, child_state.ilen); memset(child_state.input, 0, child_state.ilen); xfree(child_state.input); buffer_clear(&output); buffer_append(&output, child_state.output, child_state.olen); memset(child_state.output, 0, child_state.olen); xfree(child_state.output); } static Kex * mm_get_kex(Buffer *m) { Kex *kex; void *blob; u_int bloblen; kex = xmalloc(sizeof(*kex)); memset(kex, 0, sizeof(*kex)); kex->session_id = buffer_get_string(m, &kex->session_id_len); if ((session_id2 == NULL) || (kex->session_id_len != session_id2_len) || (memcmp(kex->session_id, session_id2, session_id2_len) != 0)) fatal("mm_get_get: internal error: bad session id"); kex->we_need = buffer_get_int(m); kex->server = 1; kex->hostkey_type = buffer_get_int(m); kex->kex_type = buffer_get_int(m); blob = buffer_get_string(m, &bloblen); buffer_init(&kex->my); buffer_append(&kex->my, blob, bloblen); xfree(blob); blob = buffer_get_string(m, &bloblen); buffer_init(&kex->peer); buffer_append(&kex->peer, blob, bloblen); xfree(blob); kex->done = 1; kex->flags = buffer_get_int(m); kex->client_version_string = buffer_get_string(m, NULL); kex->server_version_string = buffer_get_string(m, NULL); kex->load_host_key=&get_hostkey_by_type; kex->host_key_index=&get_hostkey_index; return (kex); } /* This function requries careful sanity checking */ void mm_get_keystate(struct monitor *pmonitor) { Buffer m; u_char *blob, *p; u_int bloblen, plen; debug3("%s: Waiting for new keys", __func__); buffer_init(&m); mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, &m); if (!compat20) { child_state.ssh1protoflags = buffer_get_int(&m); child_state.ssh1cipher = buffer_get_int(&m); child_state.ssh1key = buffer_get_string(&m, &child_state.ssh1keylen); child_state.ivout = buffer_get_string(&m, &child_state.ivoutlen); child_state.ivin = buffer_get_string(&m, &child_state.ivinlen); goto skip; } else { /* Get the Kex for rekeying */ *pmonitor->m_pkex = mm_get_kex(&m); } blob = buffer_get_string(&m, &bloblen); current_keys[MODE_OUT] = mm_newkeys_from_blob(blob, bloblen); xfree(blob); debug3("%s: Waiting for second key", __func__); blob = buffer_get_string(&m, &bloblen); current_keys[MODE_IN] = mm_newkeys_from_blob(blob, bloblen); xfree(blob); /* Now get sequence numbers for the packets */ packet_set_seqnr(MODE_OUT, buffer_get_int(&m)); packet_set_seqnr(MODE_IN, buffer_get_int(&m)); skip: /* Get the key context */ child_state.keyout = buffer_get_string(&m, &child_state.keyoutlen); child_state.keyin = buffer_get_string(&m, &child_state.keyinlen); debug3("%s: Getting compression state", __func__); /* Get compression state */ p = buffer_get_string(&m, &plen); if (plen != sizeof(child_state.outgoing)) fatal("%s: bad request size", __func__); memcpy(&child_state.outgoing, p, sizeof(child_state.outgoing)); xfree(p); p = buffer_get_string(&m, &plen); if (plen != sizeof(child_state.incoming)) fatal("%s: bad request size", __func__); memcpy(&child_state.incoming, p, sizeof(child_state.incoming)); xfree(p); /* Network I/O buffers */ debug3("%s: Getting Network I/O buffers", __func__); child_state.input = buffer_get_string(&m, &child_state.ilen); child_state.output = buffer_get_string(&m, &child_state.olen); buffer_free(&m); } /* Allocation functions for zlib */ void * mm_zalloc(struct mm_master *mm, u_int ncount, u_int size) { size_t len = (size_t) size * ncount; void *address; if (len == 0 || ncount > SIZE_T_MAX / size) fatal("%s: mm_zalloc(%u, %u)", __func__, ncount, size); address = mm_malloc(mm, len); return (address); } void mm_zfree(struct mm_master *mm, void *address) { mm_free(mm, address); } void mm_init_compression(struct mm_master *mm) { outgoing_stream.zalloc = (alloc_func)mm_zalloc; outgoing_stream.zfree = (free_func)mm_zfree; outgoing_stream.opaque = mm; incoming_stream.zalloc = (alloc_func)mm_zalloc; incoming_stream.zfree = (free_func)mm_zfree; incoming_stream.opaque = mm; } /* XXX */ #define FD_CLOSEONEXEC(x) do { \ if (fcntl(x, F_SETFD, 1) == -1) \ fatal("fcntl(%d, F_SETFD)", x); \ } while (0) static void monitor_socketpair(int *pair) { #ifdef HAVE_SOCKETPAIR if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) fatal("%s: socketpair", __func__); #else fatal("%s: UsePrivilegeSeparation=yes not supported", __func__); #endif FD_CLOSEONEXEC(pair[0]); FD_CLOSEONEXEC(pair[1]); } #define MM_MEMSIZE 65536 struct monitor * monitor_init(void) { struct monitor *mon; int pair[2]; mon = xmalloc(sizeof(*mon)); monitor_socketpair(pair); mon->m_recvfd = pair[0]; mon->m_sendfd = pair[1]; /* Used to share zlib space across processes */ if (options.compression) { mon->m_zback = mm_create(NULL, MM_MEMSIZE); mon->m_zlib = mm_create(mon->m_zback, 20 * MM_MEMSIZE); /* Compression needs to share state across borders */ mm_init_compression(mon->m_zlib); } return mon; } void monitor_reinit(struct monitor *mon) { int pair[2]; monitor_socketpair(pair); mon->m_recvfd = pair[0]; mon->m_sendfd = pair[1]; }