1*0Sstevel@tonic-gate /* 2*0Sstevel@tonic-gate * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 3*0Sstevel@tonic-gate * Use is subject to license terms. 4*0Sstevel@tonic-gate */ 5*0Sstevel@tonic-gate /* 6*0Sstevel@tonic-gate * Copyright (c) 2002 Markus Friedl. All rights reserved. 7*0Sstevel@tonic-gate * 8*0Sstevel@tonic-gate * Redistribution and use in source and binary forms, with or without 9*0Sstevel@tonic-gate * modification, are permitted provided that the following conditions 10*0Sstevel@tonic-gate * are met: 11*0Sstevel@tonic-gate * 1. Redistributions of source code must retain the above copyright 12*0Sstevel@tonic-gate * notice, this list of conditions and the following disclaimer. 13*0Sstevel@tonic-gate * 2. Redistributions in binary form must reproduce the above copyright 14*0Sstevel@tonic-gate * notice, this list of conditions and the following disclaimer in the 15*0Sstevel@tonic-gate * documentation and/or other materials provided with the distribution. 16*0Sstevel@tonic-gate * 17*0Sstevel@tonic-gate * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18*0Sstevel@tonic-gate * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19*0Sstevel@tonic-gate * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20*0Sstevel@tonic-gate * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21*0Sstevel@tonic-gate * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22*0Sstevel@tonic-gate * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23*0Sstevel@tonic-gate * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24*0Sstevel@tonic-gate * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25*0Sstevel@tonic-gate * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26*0Sstevel@tonic-gate * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27*0Sstevel@tonic-gate */ 28*0Sstevel@tonic-gate #include "includes.h" 29*0Sstevel@tonic-gate RCSID("$OpenBSD: ssh-keysign.c,v 1.7 2002/07/03 14:21:05 markus Exp $"); 30*0Sstevel@tonic-gate 31*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" 32*0Sstevel@tonic-gate 33*0Sstevel@tonic-gate #include <unistd.h> 34*0Sstevel@tonic-gate 35*0Sstevel@tonic-gate #include <openssl/evp.h> 36*0Sstevel@tonic-gate #include <openssl/rand.h> 37*0Sstevel@tonic-gate #include <openssl/rsa.h> 38*0Sstevel@tonic-gate 39*0Sstevel@tonic-gate #include "log.h" 40*0Sstevel@tonic-gate #include "key.h" 41*0Sstevel@tonic-gate #include "ssh.h" 42*0Sstevel@tonic-gate #include "ssh2.h" 43*0Sstevel@tonic-gate #include "misc.h" 44*0Sstevel@tonic-gate #include "xmalloc.h" 45*0Sstevel@tonic-gate #include "buffer.h" 46*0Sstevel@tonic-gate #include "bufaux.h" 47*0Sstevel@tonic-gate #include "authfile.h" 48*0Sstevel@tonic-gate #include "msg.h" 49*0Sstevel@tonic-gate #include "canohost.h" 50*0Sstevel@tonic-gate #include "pathnames.h" 51*0Sstevel@tonic-gate #include "readconf.h" 52*0Sstevel@tonic-gate 53*0Sstevel@tonic-gate uid_t original_real_uid; /* XXX readconf.c needs this */ 54*0Sstevel@tonic-gate 55*0Sstevel@tonic-gate #ifdef HAVE___PROGNAME 56*0Sstevel@tonic-gate extern char *__progname; 57*0Sstevel@tonic-gate #else 58*0Sstevel@tonic-gate #ifndef lint 59*0Sstevel@tonic-gate char *__progname; 60*0Sstevel@tonic-gate #endif /* lint */ 61*0Sstevel@tonic-gate #endif 62*0Sstevel@tonic-gate 63*0Sstevel@tonic-gate static int 64*0Sstevel@tonic-gate valid_request(struct passwd *pw, char *host, Key **ret, u_char *data, 65*0Sstevel@tonic-gate u_int datalen) 66*0Sstevel@tonic-gate { 67*0Sstevel@tonic-gate Buffer b; 68*0Sstevel@tonic-gate Key *key; 69*0Sstevel@tonic-gate u_char *pkblob; 70*0Sstevel@tonic-gate u_int blen, len; 71*0Sstevel@tonic-gate char *pkalg, *p; 72*0Sstevel@tonic-gate int pktype, fail; 73*0Sstevel@tonic-gate 74*0Sstevel@tonic-gate fail = 0; 75*0Sstevel@tonic-gate 76*0Sstevel@tonic-gate buffer_init(&b); 77*0Sstevel@tonic-gate buffer_append(&b, data, datalen); 78*0Sstevel@tonic-gate 79*0Sstevel@tonic-gate /* session id, currently limited to SHA1 (20 bytes) */ 80*0Sstevel@tonic-gate p = buffer_get_string(&b, &len); 81*0Sstevel@tonic-gate if (len != 20) 82*0Sstevel@tonic-gate fail++; 83*0Sstevel@tonic-gate xfree(p); 84*0Sstevel@tonic-gate 85*0Sstevel@tonic-gate if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) 86*0Sstevel@tonic-gate fail++; 87*0Sstevel@tonic-gate 88*0Sstevel@tonic-gate /* server user */ 89*0Sstevel@tonic-gate buffer_skip_string(&b); 90*0Sstevel@tonic-gate 91*0Sstevel@tonic-gate /* service */ 92*0Sstevel@tonic-gate p = buffer_get_string(&b, NULL); 93*0Sstevel@tonic-gate if (strcmp("ssh-connection", p) != 0) 94*0Sstevel@tonic-gate fail++; 95*0Sstevel@tonic-gate xfree(p); 96*0Sstevel@tonic-gate 97*0Sstevel@tonic-gate /* method */ 98*0Sstevel@tonic-gate p = buffer_get_string(&b, NULL); 99*0Sstevel@tonic-gate if (strcmp("hostbased", p) != 0) 100*0Sstevel@tonic-gate fail++; 101*0Sstevel@tonic-gate xfree(p); 102*0Sstevel@tonic-gate 103*0Sstevel@tonic-gate /* pubkey */ 104*0Sstevel@tonic-gate pkalg = buffer_get_string(&b, NULL); 105*0Sstevel@tonic-gate pkblob = buffer_get_string(&b, &blen); 106*0Sstevel@tonic-gate 107*0Sstevel@tonic-gate pktype = key_type_from_name(pkalg); 108*0Sstevel@tonic-gate if (pktype == KEY_UNSPEC) 109*0Sstevel@tonic-gate fail++; 110*0Sstevel@tonic-gate else if ((key = key_from_blob(pkblob, blen)) == NULL) 111*0Sstevel@tonic-gate fail++; 112*0Sstevel@tonic-gate else if (key->type != pktype) 113*0Sstevel@tonic-gate fail++; 114*0Sstevel@tonic-gate xfree(pkalg); 115*0Sstevel@tonic-gate xfree(pkblob); 116*0Sstevel@tonic-gate 117*0Sstevel@tonic-gate /* client host name, handle trailing dot */ 118*0Sstevel@tonic-gate p = buffer_get_string(&b, &len); 119*0Sstevel@tonic-gate debug2("valid_request: check expect chost %s got %s", host, p); 120*0Sstevel@tonic-gate if (strlen(host) != len - 1) 121*0Sstevel@tonic-gate fail++; 122*0Sstevel@tonic-gate else if (p[len - 1] != '.') 123*0Sstevel@tonic-gate fail++; 124*0Sstevel@tonic-gate else if (strncasecmp(host, p, len - 1) != 0) 125*0Sstevel@tonic-gate fail++; 126*0Sstevel@tonic-gate xfree(p); 127*0Sstevel@tonic-gate 128*0Sstevel@tonic-gate /* local user */ 129*0Sstevel@tonic-gate p = buffer_get_string(&b, NULL); 130*0Sstevel@tonic-gate 131*0Sstevel@tonic-gate if (strcmp(pw->pw_name, p) != 0) 132*0Sstevel@tonic-gate fail++; 133*0Sstevel@tonic-gate xfree(p); 134*0Sstevel@tonic-gate 135*0Sstevel@tonic-gate /* end of message */ 136*0Sstevel@tonic-gate if (buffer_len(&b) != 0) 137*0Sstevel@tonic-gate fail++; 138*0Sstevel@tonic-gate 139*0Sstevel@tonic-gate debug3("valid_request: fail %d", fail); 140*0Sstevel@tonic-gate 141*0Sstevel@tonic-gate if (fail && key != NULL) 142*0Sstevel@tonic-gate key_free(key); 143*0Sstevel@tonic-gate else 144*0Sstevel@tonic-gate *ret = key; 145*0Sstevel@tonic-gate 146*0Sstevel@tonic-gate return (fail ? -1 : 0); 147*0Sstevel@tonic-gate } 148*0Sstevel@tonic-gate 149*0Sstevel@tonic-gate int 150*0Sstevel@tonic-gate main(int argc, char **argv) 151*0Sstevel@tonic-gate { 152*0Sstevel@tonic-gate Buffer b; 153*0Sstevel@tonic-gate Options options; 154*0Sstevel@tonic-gate Key *keys[2], *key; 155*0Sstevel@tonic-gate struct passwd *pw; 156*0Sstevel@tonic-gate int key_fd[2], i, found, version = 2, fd; 157*0Sstevel@tonic-gate u_char *signature, *data; 158*0Sstevel@tonic-gate char *host; 159*0Sstevel@tonic-gate u_int slen, dlen; 160*0Sstevel@tonic-gate u_int32_t rnd[256]; 161*0Sstevel@tonic-gate 162*0Sstevel@tonic-gate /* 163*0Sstevel@tonic-gate * Since these two open()s are all that's done here before 164*0Sstevel@tonic-gate * dropping privileges with setreuid(), and since having been 165*0Sstevel@tonic-gate * privileged protects ssh-keysign from core dumps and tracing, 166*0Sstevel@tonic-gate * there's no need to use Least Privilege interfaces like 167*0Sstevel@tonic-gate * setppriv(2). 168*0Sstevel@tonic-gate */ 169*0Sstevel@tonic-gate key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY); 170*0Sstevel@tonic-gate key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY); 171*0Sstevel@tonic-gate 172*0Sstevel@tonic-gate (void) setreuid(getuid(), getuid()); 173*0Sstevel@tonic-gate 174*0Sstevel@tonic-gate (void) g11n_setlocale(LC_ALL, ""); 175*0Sstevel@tonic-gate 176*0Sstevel@tonic-gate init_rng(); 177*0Sstevel@tonic-gate seed_rng(); 178*0Sstevel@tonic-gate arc4random_stir(); 179*0Sstevel@tonic-gate 180*0Sstevel@tonic-gate #ifdef DEBUG_SSH_KEYSIGN 181*0Sstevel@tonic-gate log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0); 182*0Sstevel@tonic-gate #endif 183*0Sstevel@tonic-gate 184*0Sstevel@tonic-gate /* verify that ssh-keysign is enabled by the admin */ 185*0Sstevel@tonic-gate original_real_uid = getuid(); /* XXX readconf.c needs this */ 186*0Sstevel@tonic-gate initialize_options(&options); 187*0Sstevel@tonic-gate (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options); 188*0Sstevel@tonic-gate fill_default_options(&options); 189*0Sstevel@tonic-gate if (options.hostbased_authentication != 1) 190*0Sstevel@tonic-gate fatal("Hostbased authentication not enabled in %s", 191*0Sstevel@tonic-gate _PATH_HOST_CONFIG_FILE); 192*0Sstevel@tonic-gate 193*0Sstevel@tonic-gate if (key_fd[0] == -1 && key_fd[1] == -1) 194*0Sstevel@tonic-gate fatal("could not open any host key"); 195*0Sstevel@tonic-gate 196*0Sstevel@tonic-gate if ((pw = getpwuid(getuid())) == NULL) 197*0Sstevel@tonic-gate fatal("getpwuid failed"); 198*0Sstevel@tonic-gate pw = pwcopy(pw); 199*0Sstevel@tonic-gate 200*0Sstevel@tonic-gate SSLeay_add_all_algorithms(); 201*0Sstevel@tonic-gate for (i = 0; i < 256; i++) 202*0Sstevel@tonic-gate rnd[i] = arc4random(); 203*0Sstevel@tonic-gate RAND_seed(rnd, sizeof(rnd)); 204*0Sstevel@tonic-gate 205*0Sstevel@tonic-gate found = 0; 206*0Sstevel@tonic-gate for (i = 0; i < 2; i++) { 207*0Sstevel@tonic-gate keys[i] = NULL; 208*0Sstevel@tonic-gate if (key_fd[i] == -1) 209*0Sstevel@tonic-gate continue; 210*0Sstevel@tonic-gate keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC, 211*0Sstevel@tonic-gate NULL, NULL); 212*0Sstevel@tonic-gate (void) close(key_fd[i]); 213*0Sstevel@tonic-gate if (keys[i] != NULL && keys[i]->type == KEY_RSA) { 214*0Sstevel@tonic-gate if (RSA_blinding_on(keys[i]->rsa, NULL) != 1) { 215*0Sstevel@tonic-gate error("RSA_blinding_on failed"); 216*0Sstevel@tonic-gate key_free(keys[i]); 217*0Sstevel@tonic-gate keys[i] = NULL; 218*0Sstevel@tonic-gate } 219*0Sstevel@tonic-gate } 220*0Sstevel@tonic-gate if (keys[i] != NULL) 221*0Sstevel@tonic-gate found = 1; 222*0Sstevel@tonic-gate } 223*0Sstevel@tonic-gate if (!found) 224*0Sstevel@tonic-gate fatal("no hostkey found"); 225*0Sstevel@tonic-gate 226*0Sstevel@tonic-gate buffer_init(&b); 227*0Sstevel@tonic-gate if (ssh_msg_recv(STDIN_FILENO, &b) < 0) 228*0Sstevel@tonic-gate fatal("ssh_msg_recv failed"); 229*0Sstevel@tonic-gate if (buffer_get_char(&b) != version) 230*0Sstevel@tonic-gate fatal("bad version"); 231*0Sstevel@tonic-gate fd = buffer_get_int(&b); 232*0Sstevel@tonic-gate if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO)) 233*0Sstevel@tonic-gate fatal("bad fd"); 234*0Sstevel@tonic-gate if ((host = get_local_name(fd)) == NULL) 235*0Sstevel@tonic-gate fatal("cannot get sockname for fd"); 236*0Sstevel@tonic-gate 237*0Sstevel@tonic-gate data = buffer_get_string(&b, &dlen); 238*0Sstevel@tonic-gate if (valid_request(pw, host, &key, data, dlen) < 0) 239*0Sstevel@tonic-gate fatal("not a valid request"); 240*0Sstevel@tonic-gate xfree(host); 241*0Sstevel@tonic-gate 242*0Sstevel@tonic-gate found = 0; 243*0Sstevel@tonic-gate for (i = 0; i < 2; i++) { 244*0Sstevel@tonic-gate if (keys[i] != NULL && 245*0Sstevel@tonic-gate key_equal(key, keys[i])) { 246*0Sstevel@tonic-gate found = 1; 247*0Sstevel@tonic-gate break; 248*0Sstevel@tonic-gate } 249*0Sstevel@tonic-gate } 250*0Sstevel@tonic-gate if (!found) 251*0Sstevel@tonic-gate fatal("no matching hostkey found"); 252*0Sstevel@tonic-gate 253*0Sstevel@tonic-gate if (key_sign(keys[i], &signature, &slen, data, dlen) != 0) 254*0Sstevel@tonic-gate fatal("key_sign failed"); 255*0Sstevel@tonic-gate xfree(data); 256*0Sstevel@tonic-gate 257*0Sstevel@tonic-gate /* send reply */ 258*0Sstevel@tonic-gate buffer_clear(&b); 259*0Sstevel@tonic-gate buffer_put_string(&b, signature, slen); 260*0Sstevel@tonic-gate ssh_msg_send(STDOUT_FILENO, version, &b); 261*0Sstevel@tonic-gate 262*0Sstevel@tonic-gate return (0); 263*0Sstevel@tonic-gate } 264