Annotation of src/usr.bin/ssh/ssh-keysign.c, Revision 1.18.6.1
1.1 markus 1: /*
2: * Copyright (c) 2002 Markus Friedl. All rights reserved.
3: *
4: * Redistribution and use in source and binary forms, with or without
5: * modification, are permitted provided that the following conditions
6: * are met:
7: * 1. Redistributions of source code must retain the above copyright
8: * notice, this list of conditions and the following disclaimer.
9: * 2. Redistributions in binary form must reproduce the above copyright
10: * notice, this list of conditions and the following disclaimer in the
11: * documentation and/or other materials provided with the distribution.
12: *
13: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: */
24: #include "includes.h"
1.18.6.1! brad 25: RCSID("$OpenBSD: ssh-keysign.c,v 1.19 2005/09/13 23:40:07 djm Exp $");
1.1 markus 26:
27: #include <openssl/evp.h>
1.6 markus 28: #include <openssl/rand.h>
29: #include <openssl/rsa.h>
1.1 markus 30:
31: #include "log.h"
32: #include "key.h"
1.7 markus 33: #include "ssh.h"
1.1 markus 34: #include "ssh2.h"
35: #include "misc.h"
36: #include "xmalloc.h"
37: #include "buffer.h"
38: #include "bufaux.h"
39: #include "authfile.h"
40: #include "msg.h"
1.2 markus 41: #include "canohost.h"
1.1 markus 42: #include "pathnames.h"
1.7 markus 43: #include "readconf.h"
1.17 dtucker 44: #include "uidswap.h"
1.7 markus 45:
1.12 djm 46: /* XXX readconf.c needs these */
47: uid_t original_real_uid;
1.1 markus 48:
49: static int
1.2 markus 50: valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
51: u_int datalen)
1.1 markus 52: {
53: Buffer b;
1.11 markus 54: Key *key = NULL;
1.2 markus 55: u_char *pkblob;
56: u_int blen, len;
57: char *pkalg, *p;
1.1 markus 58: int pktype, fail;
59:
60: fail = 0;
61:
62: buffer_init(&b);
63: buffer_append(&b, data, datalen);
1.4 deraadt 64:
1.3 markus 65: /* session id, currently limited to SHA1 (20 bytes) */
66: p = buffer_get_string(&b, &len);
67: if (len != 20)
68: fail++;
69: xfree(p);
70:
1.1 markus 71: if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
72: fail++;
73:
74: /* server user */
75: buffer_skip_string(&b);
76:
77: /* service */
78: p = buffer_get_string(&b, NULL);
79: if (strcmp("ssh-connection", p) != 0)
80: fail++;
81: xfree(p);
82:
83: /* method */
84: p = buffer_get_string(&b, NULL);
85: if (strcmp("hostbased", p) != 0)
86: fail++;
87: xfree(p);
88:
89: /* pubkey */
90: pkalg = buffer_get_string(&b, NULL);
91: pkblob = buffer_get_string(&b, &blen);
92:
93: pktype = key_type_from_name(pkalg);
94: if (pktype == KEY_UNSPEC)
95: fail++;
96: else if ((key = key_from_blob(pkblob, blen)) == NULL)
97: fail++;
98: else if (key->type != pktype)
99: fail++;
100: xfree(pkalg);
101: xfree(pkblob);
102:
1.2 markus 103: /* client host name, handle trailing dot */
104: p = buffer_get_string(&b, &len);
105: debug2("valid_request: check expect chost %s got %s", host, p);
106: if (strlen(host) != len - 1)
107: fail++;
108: else if (p[len - 1] != '.')
1.4 deraadt 109: fail++;
1.2 markus 110: else if (strncasecmp(host, p, len - 1) != 0)
1.4 deraadt 111: fail++;
1.2 markus 112: xfree(p);
1.1 markus 113:
114: /* local user */
115: p = buffer_get_string(&b, NULL);
1.2 markus 116:
1.1 markus 117: if (strcmp(pw->pw_name, p) != 0)
118: fail++;
119: xfree(p);
120:
121: /* end of message */
122: if (buffer_len(&b) != 0)
123: fail++;
1.15 markus 124: buffer_free(&b);
1.1 markus 125:
126: debug3("valid_request: fail %d", fail);
127:
128: if (fail && key != NULL)
129: key_free(key);
130: else
131: *ret = key;
132:
133: return (fail ? -1 : 0);
134: }
135:
136: int
137: main(int argc, char **argv)
138: {
139: Buffer b;
1.7 markus 140: Options options;
1.1 markus 141: Key *keys[2], *key;
142: struct passwd *pw;
1.2 markus 143: int key_fd[2], i, found, version = 2, fd;
1.1 markus 144: u_char *signature, *data;
1.2 markus 145: char *host;
1.1 markus 146: u_int slen, dlen;
1.6 markus 147: u_int32_t rnd[256];
1.18.6.1! brad 148:
! 149: /* Ensure that stdin and stdout are connected */
! 150: if ((fd = open(_PATH_DEVNULL, O_RDWR)) < 2)
! 151: exit(1);
! 152: /* Leave /dev/null fd iff it is attached to stderr */
! 153: if (fd > 2)
! 154: close(fd);
1.1 markus 155:
156: key_fd[0] = open(_PATH_HOST_RSA_KEY_FILE, O_RDONLY);
157: key_fd[1] = open(_PATH_HOST_DSA_KEY_FILE, O_RDONLY);
158:
1.18 dtucker 159: original_real_uid = getuid(); /* XXX readconf.c needs this */
160: if ((pw = getpwuid(original_real_uid)) == NULL)
1.17 dtucker 161: fatal("getpwuid failed");
162: pw = pwcopy(pw);
163:
164: permanently_set_uid(pw);
1.1 markus 165:
166: #ifdef DEBUG_SSH_KEYSIGN
167: log_init("ssh-keysign", SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_AUTH, 0);
1.4 deraadt 168: #endif
1.7 markus 169:
170: /* verify that ssh-keysign is enabled by the admin */
171: initialize_options(&options);
1.16 djm 172: (void)read_config_file(_PATH_HOST_CONFIG_FILE, "", &options, 0);
1.7 markus 173: fill_default_options(&options);
1.8 markus 174: if (options.enable_ssh_keysign != 1)
175: fatal("ssh-keysign not enabled in %s",
1.7 markus 176: _PATH_HOST_CONFIG_FILE);
1.1 markus 177:
178: if (key_fd[0] == -1 && key_fd[1] == -1)
179: fatal("could not open any host key");
180:
181: SSLeay_add_all_algorithms();
1.6 markus 182: for (i = 0; i < 256; i++)
183: rnd[i] = arc4random();
184: RAND_seed(rnd, sizeof(rnd));
1.1 markus 185:
186: found = 0;
187: for (i = 0; i < 2; i++) {
188: keys[i] = NULL;
189: if (key_fd[i] == -1)
190: continue;
191: keys[i] = key_load_private_pem(key_fd[i], KEY_UNSPEC,
192: NULL, NULL);
193: close(key_fd[i]);
194: if (keys[i] != NULL)
195: found = 1;
196: }
197: if (!found)
198: fatal("no hostkey found");
199:
200: buffer_init(&b);
1.9 djm 201: if (ssh_msg_recv(STDIN_FILENO, &b) < 0)
202: fatal("ssh_msg_recv failed");
1.1 markus 203: if (buffer_get_char(&b) != version)
204: fatal("bad version");
1.2 markus 205: fd = buffer_get_int(&b);
206: if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO))
207: fatal("bad fd");
208: if ((host = get_local_name(fd)) == NULL)
209: fatal("cannot get sockname for fd");
1.4 deraadt 210:
1.1 markus 211: data = buffer_get_string(&b, &dlen);
1.2 markus 212: if (valid_request(pw, host, &key, data, dlen) < 0)
1.1 markus 213: fatal("not a valid request");
1.2 markus 214: xfree(host);
1.1 markus 215:
216: found = 0;
217: for (i = 0; i < 2; i++) {
218: if (keys[i] != NULL &&
219: key_equal(key, keys[i])) {
220: found = 1;
221: break;
222: }
223: }
224: if (!found)
225: fatal("no matching hostkey found");
226:
227: if (key_sign(keys[i], &signature, &slen, data, dlen) != 0)
228: fatal("key_sign failed");
1.5 markus 229: xfree(data);
1.4 deraadt 230:
1.1 markus 231: /* send reply */
232: buffer_clear(&b);
233: buffer_put_string(&b, signature, slen);
1.14 djm 234: if (ssh_msg_send(STDOUT_FILENO, version, &b) == -1)
235: fatal("ssh_msg_send failed");
1.1 markus 236:
237: return (0);
238: }