diff options
Diffstat (limited to 'crypto/openssh/sshconnect.c')
| -rw-r--r-- | crypto/openssh/sshconnect.c | 699 |
1 files changed, 0 insertions, 699 deletions
diff --git a/crypto/openssh/sshconnect.c b/crypto/openssh/sshconnect.c deleted file mode 100644 index 80beac30680a2..0000000000000 --- a/crypto/openssh/sshconnect.c +++ /dev/null @@ -1,699 +0,0 @@ -/* - * Author: Tatu Ylonen <ylo@cs.hut.fi> - * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland - * All rights reserved - * Created: Sat Mar 18 22:15:47 1995 ylo - * Code to connect to a remote host, and to perform the client side of the - * login (authentication) dialog. - */ - -#include "includes.h" -RCSID("$OpenBSD: sshconnect.c,v 1.72 2000/05/04 09:50:22 markus Exp $"); - -#include <openssl/bn.h> -#include <openssl/dsa.h> -#include <openssl/rsa.h> - -#include "xmalloc.h" -#include "rsa.h" -#include "ssh.h" -#include "buffer.h" -#include "packet.h" -#include "uidswap.h" -#include "compat.h" -#include "readconf.h" -#include "key.h" -#include "sshconnect.h" -#include "hostfile.h" - -char *client_version_string = NULL; -char *server_version_string = NULL; - -extern Options options; -extern char *__progname; - -/* - * Connect to the given ssh server using a proxy command. - */ -int -ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, - const char *proxy_command) -{ - Buffer command; - const char *cp; - char *command_string; - int pin[2], pout[2]; - pid_t pid; - char strport[NI_MAXSERV]; - - /* Convert the port number into a string. */ - snprintf(strport, sizeof strport, "%hu", port); - - /* Build the final command string in the buffer by making the - appropriate substitutions to the given proxy command. */ - buffer_init(&command); - for (cp = proxy_command; *cp; cp++) { - if (cp[0] == '%' && cp[1] == '%') { - buffer_append(&command, "%", 1); - cp++; - continue; - } - if (cp[0] == '%' && cp[1] == 'h') { - buffer_append(&command, host, strlen(host)); - cp++; - continue; - } - if (cp[0] == '%' && cp[1] == 'p') { - buffer_append(&command, strport, strlen(strport)); - cp++; - continue; - } - buffer_append(&command, cp, 1); - } - buffer_append(&command, "\0", 1); - - /* Get the final command string. */ - command_string = buffer_ptr(&command); - - /* Create pipes for communicating with the proxy. */ - if (pipe(pin) < 0 || pipe(pout) < 0) - fatal("Could not create pipes to communicate with the proxy: %.100s", - strerror(errno)); - - debug("Executing proxy command: %.500s", command_string); - - /* Fork and execute the proxy command. */ - if ((pid = fork()) == 0) { - char *argv[10]; - - /* Child. Permanently give up superuser privileges. */ - permanently_set_uid(original_real_uid); - - /* Redirect stdin and stdout. */ - close(pin[1]); - if (pin[0] != 0) { - if (dup2(pin[0], 0) < 0) - perror("dup2 stdin"); - close(pin[0]); - } - close(pout[0]); - if (dup2(pout[1], 1) < 0) - perror("dup2 stdout"); - /* Cannot be 1 because pin allocated two descriptors. */ - close(pout[1]); - - /* Stderr is left as it is so that error messages get - printed on the user's terminal. */ - argv[0] = "/bin/sh"; - argv[1] = "-c"; - argv[2] = command_string; - argv[3] = NULL; - - /* Execute the proxy command. Note that we gave up any - extra privileges above. */ - execv("/bin/sh", argv); - perror("/bin/sh"); - exit(1); - } - /* Parent. */ - if (pid < 0) - fatal("fork failed: %.100s", strerror(errno)); - - /* Close child side of the descriptors. */ - close(pin[0]); - close(pout[1]); - - /* Free the command name. */ - buffer_free(&command); - - /* Set the connection file descriptors. */ - packet_set_connection(pout[0], pin[1]); - - return 1; -} - -/* - * Creates a (possibly privileged) socket for use as the ssh connection. - */ -int -ssh_create_socket(uid_t original_real_uid, int privileged, int family) -{ - int sock; - - /* - * If we are running as root and want to connect to a privileged - * port, bind our own socket to a privileged port. - */ - if (privileged) { - int p = IPPORT_RESERVED - 1; - sock = rresvport_af(&p, family); - if (sock < 0) - error("rresvport: af=%d %.100s", family, strerror(errno)); - else - debug("Allocated local port %d.", p); - } else { - /* - * Just create an ordinary socket on arbitrary port. We use - * the user's uid to create the socket. - */ - temporarily_use_uid(original_real_uid); - sock = socket(family, SOCK_STREAM, 0); - if (sock < 0) - error("socket: %.100s", strerror(errno)); - restore_uid(); - } - return sock; -} - -/* - * Opens a TCP/IP connection to the remote server on the given host. - * The address of the remote host will be returned in hostaddr. - * If port is 0, the default port will be used. If anonymous is zero, - * a privileged port will be allocated to make the connection. - * This requires super-user privileges if anonymous is false. - * Connection_attempts specifies the maximum number of tries (one per - * second). If proxy_command is non-NULL, it specifies the command (with %h - * and %p substituted for host and port, respectively) to use to contact - * the daemon. - */ -int -ssh_connect(const char *host, struct sockaddr_storage * hostaddr, - u_short port, int connection_attempts, - int anonymous, uid_t original_real_uid, - const char *proxy_command) -{ - int sock = -1, attempt; - struct servent *sp; - struct addrinfo hints, *ai, *aitop; - char ntop[NI_MAXHOST], strport[NI_MAXSERV]; - int gaierr; - struct linger linger; - - debug("ssh_connect: getuid %d geteuid %d anon %d", - (int) getuid(), (int) geteuid(), anonymous); - - /* Get default port if port has not been set. */ - if (port == 0) { - sp = getservbyname(SSH_SERVICE_NAME, "tcp"); - if (sp) - port = ntohs(sp->s_port); - else - port = SSH_DEFAULT_PORT; - } - /* If a proxy command is given, connect using it. */ - if (proxy_command != NULL) - return ssh_proxy_connect(host, port, original_real_uid, proxy_command); - - /* No proxy command. */ - - memset(&hints, 0, sizeof(hints)); - hints.ai_family = IPv4or6; - hints.ai_socktype = SOCK_STREAM; - snprintf(strport, sizeof strport, "%d", port); - if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) - fatal("%s: %.100s: %s", __progname, host, - gai_strerror(gaierr)); - - /* - * Try to connect several times. On some machines, the first time - * will sometimes fail. In general socket code appears to behave - * quite magically on many machines. - */ - for (attempt = 0; attempt < connection_attempts; attempt++) { - if (attempt > 0) - debug("Trying again..."); - - /* Loop through addresses for this host, and try each one in - sequence until the connection succeeds. */ - for (ai = aitop; ai; ai = ai->ai_next) { - if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) - continue; - if (getnameinfo(ai->ai_addr, ai->ai_addrlen, - ntop, sizeof(ntop), strport, sizeof(strport), - NI_NUMERICHOST|NI_NUMERICSERV) != 0) { - error("ssh_connect: getnameinfo failed"); - continue; - } - debug("Connecting to %.200s [%.100s] port %s.", - host, ntop, strport); - - /* Create a socket for connecting. */ - sock = ssh_create_socket(original_real_uid, - !anonymous && geteuid() == 0 && port < IPPORT_RESERVED, - ai->ai_family); - if (sock < 0) - continue; - - /* Connect to the host. We use the user's uid in the - * hope that it will help with tcp_wrappers showing - * the remote uid as root. - */ - temporarily_use_uid(original_real_uid); - if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { - /* Successful connection. */ - memcpy(hostaddr, ai->ai_addr, sizeof(*hostaddr)); - restore_uid(); - break; - } else { - debug("connect: %.100s", strerror(errno)); - restore_uid(); - /* - * Close the failed socket; there appear to - * be some problems when reusing a socket for - * which connect() has already returned an - * error. - */ - shutdown(sock, SHUT_RDWR); - close(sock); - } - } - if (ai) - break; /* Successful connection. */ - - /* Sleep a moment before retrying. */ - sleep(1); - } - - freeaddrinfo(aitop); - - /* Return failure if we didn't get a successful connection. */ - if (attempt >= connection_attempts) - return 0; - - debug("Connection established."); - - /* - * Set socket options. We would like the socket to disappear as soon - * as it has been closed for whatever reason. - */ - /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ - linger.l_onoff = 1; - linger.l_linger = 5; - setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); - - /* Set the connection. */ - packet_set_connection(sock, sock); - - return 1; -} - -char * -chop(char *s) -{ - char *t = s; - while (*t) { - if(*t == '\n' || *t == '\r') { - *t = '\0'; - return s; - } - t++; - } - return s; - -} - -/* - * Waits for the server identification string, and sends our own - * identification string. - */ -void -ssh_exchange_identification() -{ - char buf[256], remote_version[256]; /* must be same size! */ - int remote_major, remote_minor, i, mismatch; - int connection_in = packet_get_connection_in(); - int connection_out = packet_get_connection_out(); - - /* Read other side\'s version identification. */ - for (i = 0; i < sizeof(buf) - 1; i++) { - int len = read(connection_in, &buf[i], 1); - if (len < 0) - fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); - if (len != 1) - fatal("ssh_exchange_identification: Connection closed by remote host"); - if (buf[i] == '\r') { - buf[i] = '\n'; - buf[i + 1] = 0; - continue; /**XXX wait for \n */ - } - if (buf[i] == '\n') { - buf[i + 1] = 0; - break; - } - } - buf[sizeof(buf) - 1] = 0; - server_version_string = xstrdup(buf); - - /* - * Check that the versions match. In future this might accept - * several versions and set appropriate flags to handle them. - */ - if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", - &remote_major, &remote_minor, remote_version) != 3) - fatal("Bad remote protocol version identification: '%.100s'", buf); - debug("Remote protocol version %d.%d, remote software version %.100s", - remote_major, remote_minor, remote_version); - - compat_datafellows(remote_version); - mismatch = 0; - - switch(remote_major) { - case 1: - if (remote_minor == 99 && - (options.protocol & SSH_PROTO_2) && - !(options.protocol & SSH_PROTO_1_PREFERRED)) { - enable_compat20(); - break; - } - if (!(options.protocol & SSH_PROTO_1)) { - mismatch = 1; - break; - } - if (remote_minor < 3) { - fatal("Remote machine has too old SSH software version."); - } else if (remote_minor == 3) { - /* We speak 1.3, too. */ - enable_compat13(); - if (options.forward_agent) { - log("Agent forwarding disabled for protocol 1.3"); - options.forward_agent = 0; - } - } - break; - case 2: - if (options.protocol & SSH_PROTO_2) { - enable_compat20(); - break; - } - /* FALLTHROUGH */ - default: - mismatch = 1; - break; - } - if (mismatch) - fatal("Protocol major versions differ: %d vs. %d", - (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, - remote_major); - if (compat20) - packet_set_ssh2_format(); - /* Send our own protocol version identification. */ - snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", - compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, - compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1, - SSH_VERSION); - if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) - fatal("write: %.100s", strerror(errno)); - client_version_string = xstrdup(buf); - chop(client_version_string); - chop(server_version_string); - debug("Local version string %.100s", client_version_string); -} - -int -read_yes_or_no(const char *prompt, int defval) -{ - char buf[1024]; - FILE *f; - int retval = -1; - - if (isatty(0)) - f = stdin; - else - f = fopen("/dev/tty", "rw"); - - if (f == NULL) - return 0; - - fflush(stdout); - - while (1) { - fprintf(stderr, "%s", prompt); - if (fgets(buf, sizeof(buf), f) == NULL) { - /* Print a newline (the prompt probably didn\'t have one). */ - fprintf(stderr, "\n"); - strlcpy(buf, "no", sizeof buf); - } - /* Remove newline from response. */ - if (strchr(buf, '\n')) - *strchr(buf, '\n') = 0; - - if (buf[0] == 0) - retval = defval; - if (strcmp(buf, "yes") == 0) - retval = 1; - if (strcmp(buf, "no") == 0) - retval = 0; - - if (retval != -1) { - if (f != stdin) - fclose(f); - return retval; - } - } -} - -/* - * check whether the supplied host key is valid, return only if ok. - */ - -void -check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, - const char *user_hostfile, const char *system_hostfile) -{ - Key *file_key; - char *type = key_type(host_key); - char *ip = NULL; - char hostline[1000], *hostp; - HostStatus host_status; - HostStatus ip_status; - int local = 0, host_ip_differ = 0; - char ntop[NI_MAXHOST]; - - /* - * Force accepting of the host key for loopback/localhost. The - * problem is that if the home directory is NFS-mounted to multiple - * machines, localhost will refer to a different machine in each of - * them, and the user will get bogus HOST_CHANGED warnings. This - * essentially disables host authentication for localhost; however, - * this is probably not a real problem. - */ - /** hostaddr == 0! */ - switch (hostaddr->sa_family) { - case AF_INET: - local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; - break; - case AF_INET6: - local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); - break; - default: - local = 0; - break; - } - if (local) { - debug("Forcing accepting of host key for loopback/localhost."); - return; - } - - /* - * Turn off check_host_ip for proxy connects, since - * we don't have the remote ip-address - */ - if (options.proxy_command != NULL && options.check_host_ip) - options.check_host_ip = 0; - - if (options.check_host_ip) { - if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop), - NULL, 0, NI_NUMERICHOST) != 0) - fatal("check_host_key: getnameinfo failed"); - ip = xstrdup(ntop); - } - - /* - * Store the host key from the known host file in here so that we can - * compare it with the key for the IP address. - */ - file_key = key_new(host_key->type); - - /* - * Check if the host key is present in the user\'s list of known - * hosts or in the systemwide list. - */ - host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key); - if (host_status == HOST_NEW) - host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key); - /* - * Also perform check for the ip address, skip the check if we are - * localhost or the hostname was an ip address to begin with - */ - if (options.check_host_ip && !local && strcmp(host, ip)) { - Key *ip_key = key_new(host_key->type); - ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key); - - if (ip_status == HOST_NEW) - ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key); - if (host_status == HOST_CHANGED && - (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) - host_ip_differ = 1; - - key_free(ip_key); - } else - ip_status = host_status; - - key_free(file_key); - - switch (host_status) { - case HOST_OK: - /* The host is known and the key matches. */ - debug("Host '%.200s' is known and matches the %s host key.", - host, type); - if (options.check_host_ip) { - if (ip_status == HOST_NEW) { - if (!add_host_to_hostfile(user_hostfile, ip, host_key)) - log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).", - type, ip, user_hostfile); - else - log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.", - type, ip); - } else if (ip_status != HOST_OK) - log("Warning: the %s host key for '%.200s' differs from the key for the IP address '%.30s'", - type, host, ip); - } - break; - case HOST_NEW: - /* The host is new. */ - if (options.strict_host_key_checking == 1) { - /* User has requested strict host key checking. We will not add the host key - automatically. The only alternative left is to abort. */ - fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host); - } else if (options.strict_host_key_checking == 2) { - /* The default */ - char prompt[1024]; - char *fp = key_fingerprint(host_key); - snprintf(prompt, sizeof(prompt), - "The authenticity of host '%.200s' can't be established.\n" - "%s key fingerprint is %s.\n" - "Are you sure you want to continue connecting (yes/no)? ", - host, type, fp); - if (!read_yes_or_no(prompt, -1)) - fatal("Aborted by user!\n"); - } - if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) { - snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); - hostp = hostline; - } else - hostp = host; - - /* If not in strict mode, add the key automatically to the local known_hosts file. */ - if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) - log("Failed to add the host to the list of known hosts (%.500s).", - user_hostfile); - else - log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.", - hostp, type); - break; - case HOST_CHANGED: - if (options.check_host_ip && host_ip_differ) { - char *msg; - if (ip_status == HOST_NEW) - msg = "is unknown"; - else if (ip_status == HOST_OK) - msg = "is unchanged"; - else - msg = "has a different value"; - error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); - error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); - error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); - error("The %s host key for %s has changed,", type, host); - error("and the key for the according IP address %s", ip); - error("%s. This could either mean that", msg); - error("DNS SPOOFING is happening or the IP address for the host"); - error("and its host key have changed at the same time"); - } - /* The host key has changed. */ - error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); - error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); - error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); - error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); - error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); - error("It is also possible that the %s host key has just been changed.", type); - error("Please contact your system administrator."); - error("Add correct host key in %.100s to get rid of this message.", - user_hostfile); - - /* - * If strict host key checking is in use, the user will have - * to edit the key manually and we can only abort. - */ - if (options.strict_host_key_checking) - fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host); - - /* - * If strict host key checking has not been requested, allow - * the connection but without password authentication or - * agent forwarding. - */ - if (options.password_authentication) { - error("Password authentication is disabled to avoid trojan horses."); - options.password_authentication = 0; - } - if (options.forward_agent) { - error("Agent forwarding is disabled to avoid trojan horses."); - options.forward_agent = 0; - } - /* - * XXX Should permit the user to change to use the new id. - * This could be done by converting the host key to an - * identifying sentence, tell that the host identifies itself - * by that sentence, and ask the user if he/she whishes to - * accept the authentication. - */ - break; - } - if (options.check_host_ip) - xfree(ip); -} - -/* - * Starts a dialog with the server, and authenticates the current user on the - * server. This does not need any extra privileges. The basic connection - * to the server must already have been established before this is called. - * If login fails, this function prints an error and never returns. - * This function does not require super-user privileges. - */ -void -ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, - struct sockaddr *hostaddr, uid_t original_real_uid) -{ - struct passwd *pw; - char *host, *cp; - char *server_user, *local_user; - - /* Get local user name. Use it as server user if no user name was given. */ - pw = getpwuid(original_real_uid); - if (!pw) - fatal("User id %d not found from user database.", original_real_uid); - local_user = xstrdup(pw->pw_name); - server_user = options.user ? options.user : local_user; - - /* Convert the user-supplied hostname into all lowercase. */ - host = xstrdup(orighost); - for (cp = host; *cp; cp++) - if (isupper(*cp)) - *cp = tolower(*cp); - - /* Exchange protocol version identification strings with the server. */ - ssh_exchange_identification(); - - /* Put the connection into non-blocking mode. */ - packet_set_nonblocking(); - - /* key exchange */ - /* authenticate user */ - if (compat20) { - ssh_kex2(host, hostaddr); - ssh_userauth2(server_user, host); - } else { - ssh_kex(host, hostaddr); - ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key); - } -} |