Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.310
1.310 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.309 2018/12/27 03:25:25 djm Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
1.295 djm 22: #include <net/if.h>
1.187 stevesk 23: #include <netinet/in.h>
1.172 stevesk 24:
1.176 stevesk 25: #include <ctype.h>
1.190 stevesk 26: #include <errno.h>
1.216 dtucker 27: #include <fcntl.h>
1.191 stevesk 28: #include <netdb.h>
1.172 stevesk 29: #include <paths.h>
1.199 deraadt 30: #include <signal.h>
1.188 stevesk 31: #include <pwd.h>
1.198 stevesk 32: #include <stdio.h>
1.196 stevesk 33: #include <stdlib.h>
1.193 stevesk 34: #include <string.h>
1.192 stevesk 35: #include <unistd.h>
1.295 djm 36: #include <ifaddrs.h>
1.71 markus 37:
1.199 deraadt 38: #include "xmalloc.h"
1.91 markus 39: #include "ssh.h"
1.299 markus 40: #include "sshbuf.h"
1.1 deraadt 41: #include "packet.h"
1.21 markus 42: #include "compat.h"
1.300 markus 43: #include "sshkey.h"
1.71 markus 44: #include "sshconnect.h"
1.58 markus 45: #include "hostfile.h"
1.91 markus 46: #include "log.h"
1.251 millert 47: #include "misc.h"
1.91 markus 48: #include "readconf.h"
49: #include "atomicio.h"
1.140 jakob 50: #include "dns.h"
1.239 djm 51: #include "monitor_fdpass.h"
1.219 djm 52: #include "ssh2.h"
1.186 stevesk 53: #include "version.h"
1.252 djm 54: #include "authfile.h"
55: #include "ssherr.h"
1.266 jcs 56: #include "authfd.h"
1.309 djm 57: #include "kex.h"
1.310 ! djm 58:
! 59: #include "opacket.h" /* XXX */
! 60: extern struct ssh *active_state; /* XXX */
1.140 jakob 61:
1.279 markus 62: struct sshkey *previous_host_key = NULL;
1.59 markus 63:
1.169 stevesk 64: static int matching_host_key_dns = 0;
1.145 jakob 65:
1.227 djm 66: static pid_t proxy_command_pid = 0;
67:
1.124 markus 68: /* import */
1.307 djm 69: extern int debug_flag;
1.43 markus 70: extern Options options;
1.50 markus 71: extern char *__progname;
1.91 markus 72:
1.279 markus 73: static int show_other_keys(struct hostkeys *, struct sshkey *);
74: static void warn_changed_key(struct sshkey *);
1.132 markus 75:
1.239 djm 76: /* Expand a proxy command */
77: static char *
78: expand_proxy_command(const char *proxy_command, const char *user,
79: const char *host, int port)
80: {
81: char *tmp, *ret, strport[NI_MAXSERV];
82:
1.241 djm 83: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 84: xasprintf(&tmp, "exec %s", proxy_command);
85: ret = percent_expand(tmp, "h", host, "p", strport,
86: "r", options.user, (char *)NULL);
87: free(tmp);
88: return ret;
89: }
90:
1.307 djm 91: static void
92: stderr_null(void)
93: {
94: int devnull;
95:
96: if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) {
97: error("Can't open %s for stderr redirection: %s",
98: _PATH_DEVNULL, strerror(errno));
99: return;
100: }
101: if (devnull == STDERR_FILENO)
102: return;
103: if (dup2(devnull, STDERR_FILENO) == -1)
104: error("Cannot redirect stderr to %s", _PATH_DEVNULL);
105: if (devnull > STDERR_FILENO)
106: close(devnull);
107: }
108:
1.239 djm 109: /*
110: * Connect to the given ssh server using a proxy command that passes a
111: * a connected fd back to us.
112: */
113: static int
1.286 djm 114: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
1.239 djm 115: const char *proxy_command)
116: {
117: char *command_string;
118: int sp[2], sock;
119: pid_t pid;
120: char *shell;
121:
122: if ((shell = getenv("SHELL")) == NULL)
123: shell = _PATH_BSHELL;
124:
125: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
126: fatal("Could not create socketpair to communicate with "
127: "proxy dialer: %.100s", strerror(errno));
128:
129: command_string = expand_proxy_command(proxy_command, options.user,
130: host, port);
131: debug("Executing proxy dialer command: %.500s", command_string);
132:
133: /* Fork and execute the proxy command. */
134: if ((pid = fork()) == 0) {
135: char *argv[10];
136:
137: close(sp[1]);
138: /* Redirect stdin and stdout. */
139: if (sp[0] != 0) {
140: if (dup2(sp[0], 0) < 0)
141: perror("dup2 stdin");
142: }
143: if (sp[0] != 1) {
144: if (dup2(sp[0], 1) < 0)
145: perror("dup2 stdout");
146: }
147: if (sp[0] >= 2)
148: close(sp[0]);
149:
150: /*
1.307 djm 151: * Stderr is left for non-ControlPersist connections is so
152: * error messages may be printed on the user's terminal.
1.239 djm 153: */
1.308 dtucker 154: if (!debug_flag && options.control_path != NULL &&
155: options.control_persist)
1.307 djm 156: stderr_null();
157:
1.239 djm 158: argv[0] = shell;
159: argv[1] = "-c";
160: argv[2] = command_string;
161: argv[3] = NULL;
162:
163: /*
164: * Execute the proxy command.
165: * Note that we gave up any extra privileges above.
166: */
167: execv(argv[0], argv);
168: perror(argv[0]);
169: exit(1);
170: }
171: /* Parent. */
172: if (pid < 0)
173: fatal("fork failed: %.100s", strerror(errno));
174: close(sp[0]);
175: free(command_string);
176:
177: if ((sock = mm_receive_fd(sp[1])) == -1)
178: fatal("proxy dialer did not pass back a connection");
1.271 markus 179: close(sp[1]);
1.239 djm 180:
181: while (waitpid(pid, NULL, 0) == -1)
182: if (errno != EINTR)
183: fatal("Couldn't wait for child: %s", strerror(errno));
184:
185: /* Set the connection file descriptors. */
1.286 djm 186: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
187: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 188:
189: return 0;
190: }
191:
1.39 deraadt 192: /*
193: * Connect to the given ssh server using a proxy command.
194: */
1.109 itojun 195: static int
1.286 djm 196: ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
197: const char *proxy_command)
1.1 deraadt 198: {
1.239 djm 199: char *command_string;
1.38 markus 200: int pin[2], pout[2];
1.69 deraadt 201: pid_t pid;
1.239 djm 202: char *shell;
1.237 markus 203:
1.226 djm 204: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 205: shell = _PATH_BSHELL;
1.38 markus 206:
207: /* Create pipes for communicating with the proxy. */
208: if (pipe(pin) < 0 || pipe(pout) < 0)
209: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 210: strerror(errno));
1.38 markus 211:
1.239 djm 212: command_string = expand_proxy_command(proxy_command, options.user,
213: host, port);
1.38 markus 214: debug("Executing proxy command: %.500s", command_string);
215:
216: /* Fork and execute the proxy command. */
217: if ((pid = fork()) == 0) {
218: char *argv[10];
219:
220: /* Redirect stdin and stdout. */
221: close(pin[1]);
222: if (pin[0] != 0) {
223: if (dup2(pin[0], 0) < 0)
224: perror("dup2 stdin");
225: close(pin[0]);
226: }
227: close(pout[0]);
228: if (dup2(pout[1], 1) < 0)
229: perror("dup2 stdout");
230: /* Cannot be 1 because pin allocated two descriptors. */
231: close(pout[1]);
232:
1.307 djm 233: /*
234: * Stderr is left for non-ControlPersist connections is so
235: * error messages may be printed on the user's terminal.
236: */
1.308 dtucker 237: if (!debug_flag && options.control_path != NULL &&
238: options.control_persist)
1.307 djm 239: stderr_null();
240:
1.201 djm 241: argv[0] = shell;
1.38 markus 242: argv[1] = "-c";
243: argv[2] = command_string;
244: argv[3] = NULL;
245:
246: /* Execute the proxy command. Note that we gave up any
247: extra privileges above. */
1.232 djm 248: signal(SIGPIPE, SIG_DFL);
1.89 markus 249: execv(argv[0], argv);
250: perror(argv[0]);
1.38 markus 251: exit(1);
252: }
253: /* Parent. */
254: if (pid < 0)
255: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 256: else
257: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 258:
259: /* Close child side of the descriptors. */
260: close(pin[0]);
261: close(pout[1]);
262:
263: /* Free the command name. */
1.238 djm 264: free(command_string);
1.38 markus 265:
266: /* Set the connection file descriptors. */
1.286 djm 267: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
268: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 269:
1.110 markus 270: return 0;
1.227 djm 271: }
272:
273: void
274: ssh_kill_proxy_command(void)
275: {
276: /*
277: * Send SIGHUP to proxy command if used. We don't wait() in
278: * case it hangs and instead rely on init to reap the child
279: */
280: if (proxy_command_pid > 1)
1.228 djm 281: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 282: }
283:
1.39 deraadt 284: /*
1.295 djm 285: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 286: * address that matches the desired address family on the specified interface.
1.295 djm 287: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
288: */
289: static int
290: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
291: struct sockaddr_storage *resultp, socklen_t *rlenp)
292: {
293: struct sockaddr_in6 *sa6;
294: struct sockaddr_in *sa;
295: struct in6_addr *v6addr;
296: const struct ifaddrs *ifa;
297: int allow_local;
298:
299: /*
300: * Prefer addresses that are not loopback or linklocal, but use them
301: * if nothing else matches.
302: */
303: for (allow_local = 0; allow_local < 2; allow_local++) {
304: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
305: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
306: (ifa->ifa_flags & IFF_UP) == 0 ||
307: ifa->ifa_addr->sa_family != af ||
308: strcmp(ifa->ifa_name, options.bind_interface) != 0)
309: continue;
310: switch (ifa->ifa_addr->sa_family) {
311: case AF_INET:
312: sa = (struct sockaddr_in *)ifa->ifa_addr;
313: if (!allow_local && sa->sin_addr.s_addr ==
314: htonl(INADDR_LOOPBACK))
315: continue;
316: if (*rlenp < sizeof(struct sockaddr_in)) {
317: error("%s: v4 addr doesn't fit",
318: __func__);
319: return -1;
320: }
321: *rlenp = sizeof(struct sockaddr_in);
322: memcpy(resultp, sa, *rlenp);
323: return 0;
324: case AF_INET6:
325: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
326: v6addr = &sa6->sin6_addr;
327: if (!allow_local &&
328: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
329: IN6_IS_ADDR_LOOPBACK(v6addr)))
330: continue;
331: if (*rlenp < sizeof(struct sockaddr_in6)) {
332: error("%s: v6 addr doesn't fit",
333: __func__);
334: return -1;
335: }
336: *rlenp = sizeof(struct sockaddr_in6);
337: memcpy(resultp, sa6, *rlenp);
338: return 0;
339: }
340: }
341: }
342: return -1;
343: }
344:
345: /*
1.303 dtucker 346: * Creates a socket for use as the ssh connection.
1.39 deraadt 347: */
1.109 itojun 348: static int
1.302 dtucker 349: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 350: {
1.301 dtucker 351: int sock, r;
1.295 djm 352: struct sockaddr_storage bindaddr;
353: socklen_t bindaddrlen = 0;
1.246 djm 354: struct addrinfo hints, *res = NULL;
1.295 djm 355: struct ifaddrs *ifaddrs = NULL;
356: char ntop[NI_MAXHOST];
1.1 deraadt 357:
1.217 dtucker 358: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 359: if (sock < 0) {
1.240 djm 360: error("socket: %s", strerror(errno));
1.216 dtucker 361: return -1;
362: }
363: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 364:
365: /* Bind the socket to an alternative local IP address */
1.302 dtucker 366: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 367: return sock;
368:
1.295 djm 369: if (options.bind_address != NULL) {
1.246 djm 370: memset(&hints, 0, sizeof(hints));
371: hints.ai_family = ai->ai_family;
372: hints.ai_socktype = ai->ai_socktype;
373: hints.ai_protocol = ai->ai_protocol;
374: hints.ai_flags = AI_PASSIVE;
1.295 djm 375: if ((r = getaddrinfo(options.bind_address, NULL,
376: &hints, &res)) != 0) {
1.246 djm 377: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 378: ssh_gai_strerror(r));
379: goto fail;
380: }
1.296 dtucker 381: if (res == NULL) {
1.295 djm 382: error("getaddrinfo: no addrs");
383: goto fail;
384: }
385: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
386: bindaddrlen = res->ai_addrlen;
387: } else if (options.bind_interface != NULL) {
388: if ((r = getifaddrs(&ifaddrs)) != 0) {
389: error("getifaddrs: %s: %s", options.bind_interface,
390: strerror(errno));
391: goto fail;
392: }
393: bindaddrlen = sizeof(bindaddr);
394: if (check_ifaddrs(options.bind_interface, ai->ai_family,
395: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
396: logit("getifaddrs: %s: no suitable addresses",
397: options.bind_interface);
398: goto fail;
1.246 djm 399: }
1.105 markus 400: }
1.295 djm 401: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
402: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
403: error("%s: getnameinfo failed: %s", __func__,
404: ssh_gai_strerror(r));
405: goto fail;
406: }
1.301 dtucker 407: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 408: error("bind %s: %s", ntop, strerror(errno));
409: goto fail;
1.38 markus 410: }
1.295 djm 411: debug("%s: bound to %s", __func__, ntop);
412: /* success */
413: goto out;
414: fail:
415: close(sock);
416: sock = -1;
417: out:
1.246 djm 418: if (res != NULL)
419: freeaddrinfo(res);
1.295 djm 420: if (ifaddrs != NULL)
421: freeifaddrs(ifaddrs);
1.38 markus 422: return sock;
1.1 deraadt 423: }
424:
1.282 djm 425: /*
1.49 markus 426: * Opens a TCP/IP connection to the remote server on the given host.
427: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 428: * If port is 0, the default port will be used.
1.39 deraadt 429: * Connection_attempts specifies the maximum number of tries (one per
430: * second). If proxy_command is non-NULL, it specifies the command (with %h
431: * and %p substituted for host and port, respectively) to use to contact
432: * the daemon.
433: */
1.241 djm 434: static int
1.286 djm 435: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 436: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 437: int connection_attempts, int *timeout_ms, int want_keepalive)
1.1 deraadt 438: {
1.90 markus 439: int on = 1;
1.290 djm 440: int oerrno, sock = -1, attempt;
1.90 markus 441: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 442: struct addrinfo *ai;
1.38 markus 443:
1.302 dtucker 444: debug2("%s", __func__);
1.268 djm 445: memset(ntop, 0, sizeof(ntop));
446: memset(strport, 0, sizeof(strport));
1.38 markus 447:
1.181 markus 448: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 449: if (attempt > 0) {
450: /* Sleep a moment before retrying. */
451: sleep(1);
1.38 markus 452: debug("Trying again...");
1.200 markus 453: }
1.181 markus 454: /*
455: * Loop through addresses for this host, and try each one in
456: * sequence until the connection succeeds.
457: */
1.49 markus 458: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 459: if (ai->ai_family != AF_INET &&
1.290 djm 460: ai->ai_family != AF_INET6) {
461: errno = EAFNOSUPPORT;
1.49 markus 462: continue;
1.290 djm 463: }
1.49 markus 464: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
465: ntop, sizeof(ntop), strport, sizeof(strport),
466: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 467: oerrno = errno;
1.265 djm 468: error("%s: getnameinfo failed", __func__);
1.290 djm 469: errno = oerrno;
1.49 markus 470: continue;
471: }
472: debug("Connecting to %.200s [%.100s] port %s.",
473: host, ntop, strport);
474:
475: /* Create a socket for connecting. */
1.302 dtucker 476: sock = ssh_create_socket(ai);
1.292 stsp 477: if (sock < 0) {
1.110 markus 478: /* Any error is already output */
1.290 djm 479: errno = 0;
1.49 markus 480: continue;
1.292 stsp 481: }
1.49 markus 482:
1.141 djm 483: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 484: timeout_ms) >= 0) {
1.49 markus 485: /* Successful connection. */
1.102 markus 486: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 487: break;
1.49 markus 488: } else {
1.290 djm 489: oerrno = errno;
1.131 itojun 490: debug("connect to address %s port %s: %s",
491: ntop, strport, strerror(errno));
1.38 markus 492: close(sock);
1.181 markus 493: sock = -1;
1.290 djm 494: errno = oerrno;
1.38 markus 495: }
496: }
1.181 markus 497: if (sock != -1)
1.49 markus 498: break; /* Successful connection. */
1.38 markus 499: }
1.49 markus 500:
1.38 markus 501: /* Return failure if we didn't get a successful connection. */
1.181 markus 502: if (sock == -1) {
1.159 markus 503: error("ssh: connect to host %s port %s: %s",
1.290 djm 504: host, strport, errno == 0 ? "failure" : strerror(errno));
505: return -1;
1.130 itojun 506: }
1.38 markus 507:
508: debug("Connection established.");
1.90 markus 509:
1.155 markus 510: /* Set SO_KEEPALIVE if requested. */
1.202 djm 511: if (want_keepalive &&
1.90 markus 512: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
513: sizeof(on)) < 0)
514: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 515:
516: /* Set the connection. */
1.286 djm 517: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
518: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 519:
1.286 djm 520: return 0;
1.59 markus 521: }
522:
1.241 djm 523: int
1.286 djm 524: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 525: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 526: int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 527: {
528: if (options.proxy_command == NULL) {
1.286 djm 529: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.302 dtucker 530: family, connection_attempts, timeout_ms, want_keepalive);
1.241 djm 531: } else if (strcmp(options.proxy_command, "-") == 0) {
1.286 djm 532: if ((ssh_packet_set_connection(ssh,
533: STDIN_FILENO, STDOUT_FILENO)) == NULL)
534: return -1; /* ssh_packet_set_connection logs error */
535: return 0;
1.241 djm 536: } else if (options.proxy_use_fdpass) {
1.286 djm 537: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 538: options.proxy_command);
539: }
1.286 djm 540: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 541: }
542:
1.96 markus 543: /* defaults to 'no' */
1.109 itojun 544: static int
1.112 markus 545: confirm(const char *prompt)
1.1 deraadt 546: {
1.119 markus 547: const char *msg, *again = "Please type 'yes' or 'no': ";
548: char *p;
549: int ret = -1;
1.96 markus 550:
551: if (options.batch_mode)
552: return 0;
1.119 markus 553: for (msg = prompt;;msg = again) {
554: p = read_passphrase(msg, RP_ECHO);
1.289 djm 555: if (p == NULL)
556: return 0;
557: p[strcspn(p, "\n")] = '\0';
558: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 559: ret = 0;
1.289 djm 560: else if (strcasecmp(p, "yes") == 0)
1.119 markus 561: ret = 1;
1.238 djm 562: free(p);
1.119 markus 563: if (ret != -1)
564: return ret;
1.1 deraadt 565: }
566: }
567:
1.219 djm 568: static int
1.305 djm 569: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 570: {
571: const char *reason;
1.305 djm 572: int r;
1.219 djm 573:
1.305 djm 574: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 575: error("%s", reason);
576: return 0;
577: }
1.305 djm 578: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 579: error("Certificate for %s contains unsupported "
580: "critical options(s)", host);
1.219 djm 581: return 0;
582: }
1.305 djm 583: if ((r = sshkey_check_cert_sigtype(key,
584: options.ca_sign_algorithms)) != 0) {
585: logit("%s: certificate signature algorithm %s: %s", __func__,
586: (key->cert == NULL || key->cert->signature_type == NULL) ?
587: "(null)" : key->cert->signature_type, ssh_err(r));
588: return 0;
589: }
590:
1.219 djm 591: return 1;
592: }
593:
1.229 djm 594: static int
595: sockaddr_is_local(struct sockaddr *hostaddr)
596: {
597: switch (hostaddr->sa_family) {
598: case AF_INET:
599: return (ntohl(((struct sockaddr_in *)hostaddr)->
600: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
601: case AF_INET6:
602: return IN6_IS_ADDR_LOOPBACK(
603: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
604: default:
605: return 0;
606: }
607: }
608:
609: /*
610: * Prepare the hostname and ip address strings that are used to lookup
611: * host keys in known_hosts files. These may have a port number appended.
612: */
613: void
614: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
615: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
616: {
617: char ntop[NI_MAXHOST];
618:
619: /*
620: * We don't have the remote ip-address for connections
621: * using a proxy command
622: */
623: if (hostfile_ipaddr != NULL) {
624: if (options.proxy_command == NULL) {
625: if (getnameinfo(hostaddr, hostaddr->sa_len,
626: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 627: fatal("%s: getnameinfo failed", __func__);
1.229 djm 628: *hostfile_ipaddr = put_host_port(ntop, port);
629: } else {
630: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
631: "command>");
632: }
633: }
634:
635: /*
636: * Allow the user to record the key under a different name or
637: * differentiate a non-standard port. This is useful for ssh
638: * tunneling over forwarded connections or if you run multiple
639: * sshd's on different ports on the same machine.
640: */
641: if (hostfile_hostname != NULL) {
642: if (options.host_key_alias != NULL) {
643: *hostfile_hostname = xstrdup(options.host_key_alias);
644: debug("using hostkeyalias: %s", *hostfile_hostname);
645: } else {
646: *hostfile_hostname = put_host_port(hostname, port);
647: }
648: }
649: }
650:
1.39 deraadt 651: /*
1.108 markus 652: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 653: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 654: */
1.197 dtucker 655: #define RDRW 0
656: #define RDONLY 1
657: #define ROQUIET 2
1.109 itojun 658: static int
1.197 dtucker 659: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 660: struct sshkey *host_key, int readonly,
1.234 djm 661: char **user_hostfiles, u_int num_user_hostfiles,
662: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 663: {
1.234 djm 664: HostStatus host_status;
665: HostStatus ip_status;
1.279 markus 666: struct sshkey *raw_key = NULL;
1.189 dtucker 667: char *ip = NULL, *host = NULL;
1.204 grunk 668: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 669: char msg[1024];
1.234 djm 670: const char *type;
671: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 672: int len, cancelled_forwarding = 0;
1.234 djm 673: int local = sockaddr_is_local(hostaddr);
1.280 markus 674: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 675: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 676: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 677: u_int i;
1.49 markus 678:
679: /*
680: * Force accepting of the host key for loopback/localhost. The
681: * problem is that if the home directory is NFS-mounted to multiple
682: * machines, localhost will refer to a different machine in each of
683: * them, and the user will get bogus HOST_CHANGED warnings. This
684: * essentially disables host authentication for localhost; however,
685: * this is probably not a real problem.
686: */
1.111 markus 687: if (options.no_host_authentication_for_localhost == 1 && local &&
688: options.host_key_alias == NULL) {
1.88 markus 689: debug("Forcing accepting of host key for "
690: "loopback/localhost.");
1.108 markus 691: return 0;
1.49 markus 692: }
1.42 markus 693:
694: /*
1.229 djm 695: * Prepare the hostname and address strings used for hostkey lookup.
696: * In some cases, these will have a port number appended.
1.42 markus 697: */
1.229 djm 698: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 699:
700: /*
1.88 markus 701: * Turn off check_host_ip if the connection is to localhost, via proxy
702: * command or if we don't have a hostname to compare with
703: */
1.189 dtucker 704: if (options.check_host_ip && (local ||
705: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 706: options.check_host_ip = 0;
1.86 markus 707:
1.229 djm 708: host_hostkeys = init_hostkeys();
1.234 djm 709: for (i = 0; i < num_user_hostfiles; i++)
710: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
711: for (i = 0; i < num_system_hostfiles; i++)
712: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 713:
714: ip_hostkeys = NULL;
715: if (!want_cert && options.check_host_ip) {
716: ip_hostkeys = init_hostkeys();
1.234 djm 717: for (i = 0; i < num_user_hostfiles; i++)
718: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
719: for (i = 0; i < num_system_hostfiles; i++)
720: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 721: }
1.38 markus 722:
1.219 djm 723: retry:
1.229 djm 724: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 725: want_cert = sshkey_is_cert(host_key);
726: type = sshkey_type(host_key);
1.219 djm 727:
1.46 markus 728: /*
1.170 djm 729: * Check if the host key is present in the user's list of known
1.40 markus 730: * hosts or in the systemwide list.
731: */
1.229 djm 732: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
733: &host_found);
734:
1.40 markus 735: /*
736: * Also perform check for the ip address, skip the check if we are
1.219 djm 737: * localhost, looking for a certificate, or the hostname was an ip
738: * address to begin with.
1.40 markus 739: */
1.229 djm 740: if (!want_cert && ip_hostkeys != NULL) {
741: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
742: &ip_found);
1.38 markus 743: if (host_status == HOST_CHANGED &&
1.229 djm 744: (ip_status != HOST_CHANGED ||
745: (ip_found != NULL &&
1.280 markus 746: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 747: host_ip_differ = 1;
748: } else
749: ip_status = host_status;
750:
751: switch (host_status) {
752: case HOST_OK:
753: /* The host is known and the key matches. */
1.219 djm 754: debug("Host '%.200s' is known and matches the %s host %s.",
755: host, type, want_cert ? "certificate" : "key");
1.229 djm 756: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
757: host_found->file, host_found->line);
1.281 djm 758: if (want_cert &&
759: !check_host_cert(options.host_key_alias == NULL ?
760: hostname : options.host_key_alias, host_key))
1.219 djm 761: goto fail;
1.88 markus 762: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 763: if (readonly || want_cert)
1.138 itojun 764: logit("%s host key for IP address "
1.108 markus 765: "'%.128s' not in list of known hosts.",
766: type, ip);
1.234 djm 767: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 768: host_key, options.hash_known_hosts))
1.138 itojun 769: logit("Failed to add the %s host key for IP "
1.108 markus 770: "address '%.128s' to the list of known "
1.262 dtucker 771: "hosts (%.500s).", type, ip,
1.234 djm 772: user_hostfiles[0]);
1.88 markus 773: else
1.138 itojun 774: logit("Warning: Permanently added the %s host "
1.108 markus 775: "key for IP address '%.128s' to the list "
776: "of known hosts.", type, ip);
1.209 grunk 777: } else if (options.visual_host_key) {
1.259 djm 778: fp = sshkey_fingerprint(host_key,
1.254 djm 779: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 780: ra = sshkey_fingerprint(host_key,
1.254 djm 781: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 782: if (fp == NULL || ra == NULL)
783: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 784: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 785: free(ra);
786: free(fp);
1.38 markus 787: }
1.257 djm 788: hostkey_trusted = 1;
1.38 markus 789: break;
790: case HOST_NEW:
1.197 dtucker 791: if (options.host_key_alias == NULL && port != 0 &&
792: port != SSH_DEFAULT_PORT) {
793: debug("checking without port identifier");
1.212 stevesk 794: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 795: ROQUIET, user_hostfiles, num_user_hostfiles,
796: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 797: debug("found matching key w/out port");
798: break;
799: }
800: }
1.219 djm 801: if (readonly || want_cert)
1.108 markus 802: goto fail;
1.38 markus 803: /* The host is new. */
1.285 djm 804: if (options.strict_host_key_checking ==
805: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 806: /*
807: * User has requested strict host key checking. We
808: * will not add the host key automatically. The only
809: * alternative left is to abort.
810: */
811: error("No %s host key is known for %.200s and you "
812: "have requested strict checking.", type, host);
813: goto fail;
1.285 djm 814: } else if (options.strict_host_key_checking ==
815: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 816: char msg1[1024], msg2[1024];
817:
1.229 djm 818: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 819: snprintf(msg1, sizeof(msg1),
1.168 djm 820: "\nbut keys of different type are already"
821: " known for this host.");
1.145 jakob 822: else
823: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 824: /* The default */
1.259 djm 825: fp = sshkey_fingerprint(host_key,
1.254 djm 826: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 827: ra = sshkey_fingerprint(host_key,
1.254 djm 828: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 829: if (fp == NULL || ra == NULL)
830: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 831: msg2[0] = '\0';
832: if (options.verify_host_key_dns) {
1.153 jakob 833: if (matching_host_key_dns)
1.145 jakob 834: snprintf(msg2, sizeof(msg2),
835: "Matching host key fingerprint"
836: " found in DNS.\n");
837: else
838: snprintf(msg2, sizeof(msg2),
839: "No matching host key fingerprint"
840: " found in DNS.\n");
841: }
1.119 markus 842: snprintf(msg, sizeof(msg),
1.108 markus 843: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 844: "established%s\n"
1.209 grunk 845: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 846: "Are you sure you want to continue connecting "
1.132 markus 847: "(yes/no)? ",
1.209 grunk 848: host, ip, msg1, type, fp,
849: options.visual_host_key ? "\n" : "",
850: options.visual_host_key ? ra : "",
851: msg2);
1.238 djm 852: free(ra);
853: free(fp);
1.119 markus 854: if (!confirm(msg))
1.108 markus 855: goto fail;
1.257 djm 856: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 857: }
1.161 djm 858: /*
1.285 djm 859: * If in "new" or "off" strict mode, add the key automatically
860: * to the local known_hosts file.
1.161 djm 861: */
1.88 markus 862: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 863: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 864: hostp = hostline;
1.161 djm 865: if (options.hash_known_hosts) {
866: /* Add hash of host and IP separately */
1.234 djm 867: r = add_host_to_hostfile(user_hostfiles[0],
868: host, host_key, options.hash_known_hosts) &&
869: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 870: host_key, options.hash_known_hosts);
871: } else {
872: /* Add unhashed "host,ip" */
1.234 djm 873: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 874: hostline, host_key,
875: options.hash_known_hosts);
876: }
877: } else {
1.234 djm 878: r = add_host_to_hostfile(user_hostfiles[0], host,
879: host_key, options.hash_known_hosts);
1.38 markus 880: hostp = host;
1.161 djm 881: }
1.38 markus 882:
1.161 djm 883: if (!r)
1.138 itojun 884: logit("Failed to add the host to the list of known "
1.234 djm 885: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 886: else
1.138 itojun 887: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 888: "list of known hosts.", hostp, type);
1.38 markus 889: break;
1.220 djm 890: case HOST_REVOKED:
891: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
892: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
893: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
894: error("The %s host key for %s is marked as revoked.", type, host);
895: error("This could mean that a stolen key is being used to");
896: error("impersonate this host.");
897:
898: /*
899: * If strict host key checking is in use, the user will have
900: * to edit the key manually and we can only abort.
901: */
1.285 djm 902: if (options.strict_host_key_checking !=
903: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 904: error("%s host key for %.200s was revoked and you have "
905: "requested strict checking.", type, host);
906: goto fail;
907: }
908: goto continue_unsafe;
909:
1.38 markus 910: case HOST_CHANGED:
1.219 djm 911: if (want_cert) {
912: /*
913: * This is only a debug() since it is valid to have
914: * CAs with wildcard DNS matches that don't match
915: * all hosts that one might visit.
916: */
917: debug("Host certificate authority does not "
1.229 djm 918: "match %s in %s:%lu", CA_MARKER,
919: host_found->file, host_found->line);
1.219 djm 920: goto fail;
921: }
1.197 dtucker 922: if (readonly == ROQUIET)
923: goto fail;
1.38 markus 924: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 925: char *key_msg;
1.38 markus 926: if (ip_status == HOST_NEW)
1.158 avsm 927: key_msg = "is unknown";
1.38 markus 928: else if (ip_status == HOST_OK)
1.158 avsm 929: key_msg = "is unchanged";
1.38 markus 930: else
1.158 avsm 931: key_msg = "has a different value";
1.38 markus 932: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
933: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
934: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 935: error("The %s host key for %s has changed,", type, host);
1.208 ian 936: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 937: error("%s. This could either mean that", key_msg);
1.38 markus 938: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 939: error("and its host key have changed at the same time.");
1.88 markus 940: if (ip_status != HOST_NEW)
1.229 djm 941: error("Offending key for IP in %s:%lu",
942: ip_found->file, ip_found->line);
1.38 markus 943: }
944: /* The host key has changed. */
1.150 jakob 945: warn_changed_key(host_key);
1.38 markus 946: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 947: user_hostfiles[0]);
1.280 markus 948: error("Offending %s key in %s:%lu",
949: sshkey_type(host_found->key),
1.229 djm 950: host_found->file, host_found->line);
1.38 markus 951:
1.40 markus 952: /*
953: * If strict host key checking is in use, the user will have
954: * to edit the key manually and we can only abort.
955: */
1.285 djm 956: if (options.strict_host_key_checking !=
957: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 958: error("%s host key for %.200s has changed and you have "
959: "requested strict checking.", type, host);
960: goto fail;
961: }
1.38 markus 962:
1.220 djm 963: continue_unsafe:
1.40 markus 964: /*
965: * If strict host key checking has not been requested, allow
1.144 djm 966: * the connection but without MITM-able authentication or
1.194 stevesk 967: * forwarding.
1.40 markus 968: */
1.38 markus 969: if (options.password_authentication) {
1.108 markus 970: error("Password authentication is disabled to avoid "
971: "man-in-the-middle attacks.");
1.38 markus 972: options.password_authentication = 0;
1.210 dtucker 973: cancelled_forwarding = 1;
1.144 djm 974: }
975: if (options.kbd_interactive_authentication) {
976: error("Keyboard-interactive authentication is disabled"
977: " to avoid man-in-the-middle attacks.");
978: options.kbd_interactive_authentication = 0;
979: options.challenge_response_authentication = 0;
1.210 dtucker 980: cancelled_forwarding = 1;
1.144 djm 981: }
982: if (options.challenge_response_authentication) {
983: error("Challenge/response authentication is disabled"
984: " to avoid man-in-the-middle attacks.");
985: options.challenge_response_authentication = 0;
1.210 dtucker 986: cancelled_forwarding = 1;
1.38 markus 987: }
988: if (options.forward_agent) {
1.108 markus 989: error("Agent forwarding is disabled to avoid "
990: "man-in-the-middle attacks.");
1.38 markus 991: options.forward_agent = 0;
1.210 dtucker 992: cancelled_forwarding = 1;
1.83 markus 993: }
994: if (options.forward_x11) {
1.108 markus 995: error("X11 forwarding is disabled to avoid "
996: "man-in-the-middle attacks.");
1.83 markus 997: options.forward_x11 = 0;
1.210 dtucker 998: cancelled_forwarding = 1;
1.83 markus 999: }
1.108 markus 1000: if (options.num_local_forwards > 0 ||
1001: options.num_remote_forwards > 0) {
1002: error("Port forwarding is disabled to avoid "
1003: "man-in-the-middle attacks.");
1004: options.num_local_forwards =
1.118 deraadt 1005: options.num_remote_forwards = 0;
1.210 dtucker 1006: cancelled_forwarding = 1;
1.194 stevesk 1007: }
1008: if (options.tun_open != SSH_TUNMODE_NO) {
1009: error("Tunnel forwarding is disabled to avoid "
1010: "man-in-the-middle attacks.");
1011: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1012: cancelled_forwarding = 1;
1.38 markus 1013: }
1.210 dtucker 1014: if (options.exit_on_forward_failure && cancelled_forwarding)
1015: fatal("Error: forwarding disabled due to host key "
1016: "check failure");
1017:
1.40 markus 1018: /*
1019: * XXX Should permit the user to change to use the new id.
1020: * This could be done by converting the host key to an
1021: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1022: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1023: * accept the authentication.
1024: */
1.38 markus 1025: break;
1.132 markus 1026: case HOST_FOUND:
1027: fatal("internal error");
1028: break;
1.88 markus 1029: }
1030:
1031: if (options.check_host_ip && host_status != HOST_CHANGED &&
1032: ip_status == HOST_CHANGED) {
1.119 markus 1033: snprintf(msg, sizeof(msg),
1034: "Warning: the %s host key for '%.200s' "
1035: "differs from the key for the IP address '%.128s'"
1.229 djm 1036: "\nOffending key for IP in %s:%lu",
1037: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1038: if (host_status == HOST_OK) {
1039: len = strlen(msg);
1040: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1041: "\nMatching host key in %s:%lu",
1042: host_found->file, host_found->line);
1.119 markus 1043: }
1.285 djm 1044: if (options.strict_host_key_checking ==
1045: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1046: strlcat(msg, "\nAre you sure you want "
1047: "to continue connecting (yes/no)? ", sizeof(msg));
1048: if (!confirm(msg))
1.108 markus 1049: goto fail;
1.285 djm 1050: } else if (options.strict_host_key_checking !=
1051: SSH_STRICT_HOSTKEY_OFF) {
1052: logit("%s", msg);
1053: error("Exiting, you have requested strict checking.");
1054: goto fail;
1.119 markus 1055: } else {
1.143 djm 1056: logit("%s", msg);
1.88 markus 1057: }
1.257 djm 1058: }
1059:
1060: if (!hostkey_trusted && options.update_hostkeys) {
1061: debug("%s: hostkey not known or explicitly trusted: "
1062: "disabling UpdateHostkeys", __func__);
1063: options.update_hostkeys = 0;
1.38 markus 1064: }
1.82 provos 1065:
1.238 djm 1066: free(ip);
1067: free(host);
1.229 djm 1068: if (host_hostkeys != NULL)
1069: free_hostkeys(host_hostkeys);
1070: if (ip_hostkeys != NULL)
1071: free_hostkeys(ip_hostkeys);
1.108 markus 1072: return 0;
1073:
1074: fail:
1.220 djm 1075: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1076: /*
1077: * No matching certificate. Downgrade cert to raw key and
1078: * search normally.
1079: */
1080: debug("No matching CA found. Retry with plain key");
1.280 markus 1081: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1082: fatal("%s: sshkey_from_private: %s",
1083: __func__, ssh_err(r));
1084: if ((r = sshkey_drop_cert(raw_key)) != 0)
1085: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1086: host_key = raw_key;
1087: goto retry;
1088: }
1.293 dtucker 1089: sshkey_free(raw_key);
1.238 djm 1090: free(ip);
1091: free(host);
1.229 djm 1092: if (host_hostkeys != NULL)
1093: free_hostkeys(host_hostkeys);
1094: if (ip_hostkeys != NULL)
1095: free_hostkeys(ip_hostkeys);
1.108 markus 1096: return -1;
1097: }
1098:
1.140 jakob 1099: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1100: int
1.279 markus 1101: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1102: {
1.267 djm 1103: u_int i;
1.250 djm 1104: int r = -1, flags = 0;
1.267 djm 1105: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1106: struct sshkey *plain = NULL;
1.229 djm 1107:
1.252 djm 1108: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1109: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1110: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1111: r = -1;
1112: goto out;
1113: }
1114:
1.267 djm 1115: if (sshkey_is_cert(host_key)) {
1116: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1117: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1118: error("%s: fingerprint CA key: %s",
1119: __func__, ssh_err(r));
1120: r = -1;
1121: goto out;
1122: }
1123: sshkey_format_cert_validity(host_key->cert,
1124: valid, sizeof(valid));
1125: debug("Server host certificate: %s %s, serial %llu "
1126: "ID \"%s\" CA %s %s valid %s",
1127: sshkey_ssh_name(host_key), fp,
1.269 djm 1128: (unsigned long long)host_key->cert->serial,
1129: host_key->cert->key_id,
1.267 djm 1130: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1131: valid);
1132: for (i = 0; i < host_key->cert->nprincipals; i++) {
1133: debug2("Server host certificate hostname: %s",
1134: host_key->cert->principals[i]);
1135: }
1136: } else {
1.276 djm 1137: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1138: }
1.252 djm 1139:
1140: if (sshkey_equal(previous_host_key, host_key)) {
1141: debug2("%s: server host key %s %s matches cached key",
1142: __func__, sshkey_type(host_key), fp);
1143: r = 0;
1144: goto out;
1145: }
1146:
1147: /* Check in RevokedHostKeys file if specified */
1148: if (options.revoked_host_keys != NULL) {
1149: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1150: switch (r) {
1151: case 0:
1152: break; /* not revoked */
1153: case SSH_ERR_KEY_REVOKED:
1154: error("Host key %s %s revoked by file %s",
1155: sshkey_type(host_key), fp,
1156: options.revoked_host_keys);
1157: r = -1;
1158: goto out;
1159: default:
1160: error("Error checking host key %s %s in "
1161: "revoked keys file %s: %s", sshkey_type(host_key),
1162: fp, options.revoked_host_keys, ssh_err(r));
1163: r = -1;
1164: goto out;
1165: }
1.250 djm 1166: }
1167:
1.247 djm 1168: if (options.verify_host_key_dns) {
1169: /*
1170: * XXX certs are not yet supported for DNS, so downgrade
1171: * them and try the plain key.
1172: */
1.252 djm 1173: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1174: goto out;
1175: if (sshkey_is_cert(plain))
1176: sshkey_drop_cert(plain);
1.247 djm 1177: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1178: if (flags & DNS_VERIFY_FOUND) {
1179: if (options.verify_host_key_dns == 1 &&
1180: flags & DNS_VERIFY_MATCH &&
1181: flags & DNS_VERIFY_SECURE) {
1.250 djm 1182: r = 0;
1.252 djm 1183: goto out;
1.247 djm 1184: }
1185: if (flags & DNS_VERIFY_MATCH) {
1186: matching_host_key_dns = 1;
1187: } else {
1.287 djm 1188: warn_changed_key(plain);
1189: error("Update the SSHFP RR in DNS "
1190: "with the new host key to get rid "
1191: "of this message.");
1.247 djm 1192: }
1.153 jakob 1193: }
1.140 jakob 1194: }
1195: }
1.250 djm 1196: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1197: options.user_hostfiles, options.num_user_hostfiles,
1198: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1199:
1.252 djm 1200: out:
1201: sshkey_free(plain);
1202: free(fp);
1.267 djm 1203: free(cafp);
1.250 djm 1204: if (r == 0 && host_key != NULL) {
1.280 markus 1205: sshkey_free(previous_host_key);
1206: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1207: }
1208:
1209: return r;
1.51 markus 1210: }
1.70 markus 1211:
1.51 markus 1212: /*
1213: * Starts a dialog with the server, and authenticates the current user on the
1214: * server. This does not need any extra privileges. The basic connection
1215: * to the server must already have been established before this is called.
1216: * If login fails, this function prints an error and never returns.
1217: * This function does not require super-user privileges.
1218: */
1219: void
1.309 djm 1220: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1221: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1222: {
1.241 djm 1223: char *host;
1.70 markus 1224: char *server_user, *local_user;
1225:
1226: local_user = xstrdup(pw->pw_name);
1227: server_user = options.user ? options.user : local_user;
1.51 markus 1228:
1229: /* Convert the user-supplied hostname into all lowercase. */
1230: host = xstrdup(orighost);
1.241 djm 1231: lowercase(host);
1.51 markus 1232:
1233: /* Exchange protocol version identification strings with the server. */
1.309 djm 1234: if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0)
1235: cleanup_exit(255); /* error already logged */
1.51 markus 1236:
1237: /* Put the connection into non-blocking mode. */
1.309 djm 1238: ssh_packet_set_nonblocking(ssh);
1.51 markus 1239:
1240: /* key exchange */
1241: /* authenticate user */
1.261 dtucker 1242: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1243: ssh_kex2(ssh, host, hostaddr, port);
1244: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1245: free(local_user);
1.97 markus 1246: }
1247:
1248: void
1249: ssh_put_password(char *password)
1250: {
1251: int size;
1252: char *padded;
1253:
1.99 deraadt 1254: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1255: packet_put_cstring(password);
1.99 deraadt 1256: return;
1257: }
1.272 deraadt 1258: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1259: padded = xcalloc(1, size);
1.97 markus 1260: strlcpy(padded, password, size);
1261: packet_put_string(padded, size);
1.245 djm 1262: explicit_bzero(padded, size);
1.238 djm 1263: free(padded);
1.132 markus 1264: }
1265:
1266: /* print all known host keys for a given host, but skip keys of given type */
1267: static int
1.279 markus 1268: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1269: {
1.242 djm 1270: int type[] = {
1271: KEY_RSA,
1272: KEY_DSA,
1273: KEY_ECDSA,
1274: KEY_ED25519,
1.297 markus 1275: KEY_XMSS,
1.242 djm 1276: -1
1277: };
1.229 djm 1278: int i, ret = 0;
1279: char *fp, *ra;
1280: const struct hostkey_entry *found;
1.132 markus 1281:
1282: for (i = 0; type[i] != -1; i++) {
1283: if (type[i] == key->type)
1284: continue;
1.229 djm 1285: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1286: continue;
1.259 djm 1287: fp = sshkey_fingerprint(found->key,
1.254 djm 1288: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1289: ra = sshkey_fingerprint(found->key,
1.254 djm 1290: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1291: if (fp == NULL || ra == NULL)
1292: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1293: logit("WARNING: %s key found for host %s\n"
1294: "in %s:%lu\n"
1295: "%s key fingerprint %s.",
1.300 markus 1296: sshkey_type(found->key),
1.229 djm 1297: found->host, found->file, found->line,
1.300 markus 1298: sshkey_type(found->key), fp);
1.229 djm 1299: if (options.visual_host_key)
1300: logit("%s", ra);
1.238 djm 1301: free(ra);
1302: free(fp);
1.229 djm 1303: ret = 1;
1.132 markus 1304: }
1.229 djm 1305: return ret;
1.150 jakob 1306: }
1307:
1308: static void
1.279 markus 1309: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1310: {
1311: char *fp;
1312:
1.259 djm 1313: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1314: SSH_FP_DEFAULT);
1.259 djm 1315: if (fp == NULL)
1316: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1317:
1318: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1319: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1320: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1321: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1322: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1323: error("It is also possible that a host key has just been changed.");
1.150 jakob 1324: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1325: sshkey_type(host_key), fp);
1.150 jakob 1326: error("Please contact your system administrator.");
1327:
1.238 djm 1328: free(fp);
1.171 reyk 1329: }
1330:
1331: /*
1332: * Execute a local command
1333: */
1334: int
1335: ssh_local_cmd(const char *args)
1336: {
1337: char *shell;
1338: pid_t pid;
1339: int status;
1.231 djm 1340: void (*osighand)(int);
1.171 reyk 1341:
1342: if (!options.permit_local_command ||
1343: args == NULL || !*args)
1344: return (1);
1345:
1.226 djm 1346: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1347: shell = _PATH_BSHELL;
1348:
1.231 djm 1349: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1350: pid = fork();
1351: if (pid == 0) {
1.232 djm 1352: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1353: debug3("Executing %s -c \"%s\"", shell, args);
1354: execl(shell, shell, "-c", args, (char *)NULL);
1355: error("Couldn't execute %s -c \"%s\": %s",
1356: shell, args, strerror(errno));
1357: _exit(1);
1358: } else if (pid == -1)
1359: fatal("fork failed: %.100s", strerror(errno));
1360: while (waitpid(pid, &status, 0) == -1)
1361: if (errno != EINTR)
1362: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1363: signal(SIGCHLD, osighand);
1.171 reyk 1364:
1365: if (!WIFEXITED(status))
1366: return (1);
1367:
1368: return (WEXITSTATUS(status));
1.266 jcs 1369: }
1370:
1371: void
1.294 djm 1372: maybe_add_key_to_agent(char *authfile, const struct sshkey *private,
1373: char *comment, char *passphrase)
1.266 jcs 1374: {
1375: int auth_sock = -1, r;
1376:
1377: if (options.add_keys_to_agent == 0)
1378: return;
1379:
1380: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1381: debug3("no authentication agent, not adding key");
1382: return;
1383: }
1384:
1385: if (options.add_keys_to_agent == 2 &&
1386: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1387: debug3("user denied adding this key");
1.273 dtucker 1388: close(auth_sock);
1.266 jcs 1389: return;
1390: }
1391:
1392: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1.297 markus 1393: (options.add_keys_to_agent == 3), 0)) == 0)
1.266 jcs 1394: debug("identity added to agent: %s", authfile);
1395: else
1396: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1397: close(auth_sock);
1.1 deraadt 1398: }
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