mirror of git://anongit.mindrot.org/openssh.git
1621 lines
45 KiB
C
1621 lines
45 KiB
C
/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* This program is the ssh daemon. It listens for connections from clients,
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* and performs authentication, executes use commands or shell, and forwards
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* information to/from the application to the user client over an encrypted
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* connection. This can also handle forwarding of X11, TCP/IP, and
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* authentication agent connections.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*
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* SSH2 implementation:
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*
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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RCSID("$OpenBSD: sshd.c,v 1.132 2000/10/13 18:34:46 markus Exp $");
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#include "xmalloc.h"
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#include "rsa.h"
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#include "ssh.h"
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#include "pty.h"
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#include "packet.h"
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#include "mpaux.h"
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#include "servconf.h"
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#include "uidswap.h"
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#include "compat.h"
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#include "buffer.h"
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#include "ssh2.h"
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#include <openssl/dh.h>
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#include <openssl/bn.h>
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#include <openssl/hmac.h>
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#include "kex.h"
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#include <openssl/dsa.h>
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#include <openssl/rsa.h>
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#include "key.h"
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#include "dsa.h"
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#include "dh.h"
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#include "auth.h"
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#include "myproposal.h"
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#include "authfile.h"
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#ifdef LIBWRAP
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#include <tcpd.h>
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#include <syslog.h>
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int allow_severity = LOG_INFO;
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int deny_severity = LOG_WARNING;
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#endif /* LIBWRAP */
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#ifndef O_NOCTTY
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#define O_NOCTTY 0
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#endif
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/* Server configuration options. */
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ServerOptions options;
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/* Name of the server configuration file. */
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char *config_file_name = SERVER_CONFIG_FILE;
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/*
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* Flag indicating whether IPv4 or IPv6. This can be set on the command line.
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* Default value is AF_UNSPEC means both IPv4 and IPv6.
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*/
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#ifdef IPV4_DEFAULT
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int IPv4or6 = AF_INET;
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#else
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int IPv4or6 = AF_UNSPEC;
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#endif
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/*
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* Debug mode flag. This can be set on the command line. If debug
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* mode is enabled, extra debugging output will be sent to the system
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* log, the daemon will not go to background, and will exit after processing
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* the first connection.
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*/
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int debug_flag = 0;
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/* Flag indicating that the daemon is being started from inetd. */
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int inetd_flag = 0;
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/* debug goes to stderr unless inetd_flag is set */
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int log_stderr = 0;
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/* argv[0] without path. */
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char *av0;
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/* Saved arguments to main(). */
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char **saved_argv;
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int saved_argc;
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/*
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* The sockets that the server is listening; this is used in the SIGHUP
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* signal handler.
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*/
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#define MAX_LISTEN_SOCKS 16
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int listen_socks[MAX_LISTEN_SOCKS];
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int num_listen_socks = 0;
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/*
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* the client's version string, passed by sshd2 in compat mode. if != NULL,
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* sshd will skip the version-number exchange
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*/
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char *client_version_string = NULL;
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char *server_version_string = NULL;
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/*
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* Any really sensitive data in the application is contained in this
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* structure. The idea is that this structure could be locked into memory so
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* that the pages do not get written into swap. However, there are some
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* problems. The private key contains BIGNUMs, and we do not (in principle)
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* have access to the internals of them, and locking just the structure is
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* not very useful. Currently, memory locking is not implemented.
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*/
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struct {
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RSA *private_key; /* Private part of empheral server key. */
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RSA *host_key; /* Private part of host key. */
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Key *dsa_host_key; /* Private DSA host key. */
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} sensitive_data;
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/*
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* Flag indicating whether the current session key has been used. This flag
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* is set whenever the key is used, and cleared when the key is regenerated.
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*/
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int key_used = 0;
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/* This is set to true when SIGHUP is received. */
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int received_sighup = 0;
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/* Public side of the server key. This value is regenerated regularly with
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the private key. */
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RSA *public_key;
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/* session identifier, used by RSA-auth */
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unsigned char session_id[16];
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/* same for ssh2 */
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unsigned char *session_id2 = NULL;
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int session_id2_len = 0;
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/* record remote hostname or ip */
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unsigned int utmp_len = MAXHOSTNAMELEN;
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/* Prototypes for various functions defined later in this file. */
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void do_ssh1_kex();
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void do_ssh2_kex();
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void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *);
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void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *);
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/*
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* Close all listening sockets
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*/
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void
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close_listen_socks(void)
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{
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int i;
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for (i = 0; i < num_listen_socks; i++)
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close(listen_socks[i]);
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num_listen_socks = -1;
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}
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/*
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* Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
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* the effect is to reread the configuration file (and to regenerate
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* the server key).
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*/
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void
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sighup_handler(int sig)
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{
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received_sighup = 1;
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signal(SIGHUP, sighup_handler);
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}
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/*
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* Called from the main program after receiving SIGHUP.
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* Restarts the server.
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*/
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void
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sighup_restart()
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{
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log("Received SIGHUP; restarting.");
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close_listen_socks();
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execv(saved_argv[0], saved_argv);
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log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno));
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exit(1);
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}
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/*
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* Generic signal handler for terminating signals in the master daemon.
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* These close the listen socket; not closing it seems to cause "Address
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* already in use" problems on some machines, which is inconvenient.
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*/
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void
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sigterm_handler(int sig)
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{
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log("Received signal %d; terminating.", sig);
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close_listen_socks();
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unlink(options.pid_file);
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exit(255);
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}
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/*
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* SIGCHLD handler. This is called whenever a child dies. This will then
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* reap any zombies left by exited c.
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*/
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void
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main_sigchld_handler(int sig)
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{
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int save_errno = errno;
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int status;
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while (waitpid(-1, &status, WNOHANG) > 0)
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;
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signal(SIGCHLD, main_sigchld_handler);
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errno = save_errno;
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}
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/*
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* Signal handler for the alarm after the login grace period has expired.
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*/
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void
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grace_alarm_handler(int sig)
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{
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/* Close the connection. */
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packet_close();
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/* Log error and exit. */
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fatal("Timeout before authentication for %s.", get_remote_ipaddr());
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}
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/*
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* Signal handler for the key regeneration alarm. Note that this
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* alarm only occurs in the daemon waiting for connections, and it does not
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* do anything with the private key or random state before forking.
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* Thus there should be no concurrency control/asynchronous execution
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* problems.
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*/
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/* XXX do we really want this work to be done in a signal handler ? -m */
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void
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key_regeneration_alarm(int sig)
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{
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int save_errno = errno;
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/* Check if we should generate a new key. */
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if (key_used) {
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/* This should really be done in the background. */
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log("Generating new %d bit RSA key.", options.server_key_bits);
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if (sensitive_data.private_key != NULL)
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RSA_free(sensitive_data.private_key);
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sensitive_data.private_key = RSA_new();
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if (public_key != NULL)
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RSA_free(public_key);
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public_key = RSA_new();
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rsa_generate_key(sensitive_data.private_key, public_key,
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options.server_key_bits);
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arc4random_stir();
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key_used = 0;
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log("RSA key generation complete.");
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}
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/* Reschedule the alarm. */
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signal(SIGALRM, key_regeneration_alarm);
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alarm(options.key_regeneration_time);
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errno = save_errno;
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}
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void
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sshd_exchange_identification(int sock_in, int sock_out)
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{
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int i, mismatch;
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int remote_major, remote_minor;
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int major, minor;
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char *s;
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char buf[256]; /* Must not be larger than remote_version. */
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char remote_version[256]; /* Must be at least as big as buf. */
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if ((options.protocol & SSH_PROTO_1) &&
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(options.protocol & SSH_PROTO_2)) {
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major = PROTOCOL_MAJOR_1;
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minor = 99;
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} else if (options.protocol & SSH_PROTO_2) {
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major = PROTOCOL_MAJOR_2;
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minor = PROTOCOL_MINOR_2;
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} else {
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major = PROTOCOL_MAJOR_1;
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minor = PROTOCOL_MINOR_1;
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}
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snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
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server_version_string = xstrdup(buf);
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if (client_version_string == NULL) {
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/* Send our protocol version identification. */
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if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
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!= strlen(server_version_string)) {
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log("Could not write ident string to %s.", get_remote_ipaddr());
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fatal_cleanup();
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}
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/* Read other side\'s version identification. */
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for (i = 0; i < sizeof(buf) - 1; i++) {
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if (atomicio(read, sock_in, &buf[i], 1) != 1) {
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log("Did not receive ident string from %s.", get_remote_ipaddr());
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fatal_cleanup();
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}
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if (buf[i] == '\r') {
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buf[i] = '\n';
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buf[i + 1] = 0;
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/* Kludge for F-Secure Macintosh < 1.0.2 */
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if (i == 12 &&
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strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
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break;
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continue;
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}
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if (buf[i] == '\n') {
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/* buf[i] == '\n' */
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buf[i + 1] = 0;
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break;
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}
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}
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buf[sizeof(buf) - 1] = 0;
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client_version_string = xstrdup(buf);
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}
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/*
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* Check that the versions match. In future this might accept
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* several versions and set appropriate flags to handle them.
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*/
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if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
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&remote_major, &remote_minor, remote_version) != 3) {
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s = "Protocol mismatch.\n";
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(void) atomicio(write, sock_out, s, strlen(s));
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close(sock_in);
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close(sock_out);
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log("Bad protocol version identification '%.100s' from %s",
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client_version_string, get_remote_ipaddr());
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fatal_cleanup();
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}
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debug("Client protocol version %d.%d; client software version %.100s",
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remote_major, remote_minor, remote_version);
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compat_datafellows(remote_version);
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mismatch = 0;
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switch(remote_major) {
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case 1:
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if (remote_minor == 99) {
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if (options.protocol & SSH_PROTO_2)
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enable_compat20();
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else
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mismatch = 1;
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break;
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}
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if (!(options.protocol & SSH_PROTO_1)) {
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mismatch = 1;
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break;
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}
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if (remote_minor < 3) {
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packet_disconnect("Your ssh version is too old and "
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"is no longer supported. Please install a newer version.");
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} else if (remote_minor == 3) {
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/* note that this disables agent-forwarding */
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enable_compat13();
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}
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break;
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case 2:
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if (options.protocol & SSH_PROTO_2) {
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enable_compat20();
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break;
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}
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/* FALLTHROUGH */
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default:
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mismatch = 1;
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break;
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}
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chop(server_version_string);
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chop(client_version_string);
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debug("Local version string %.200s", server_version_string);
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if (mismatch) {
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s = "Protocol major versions differ.\n";
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(void) atomicio(write, sock_out, s, strlen(s));
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close(sock_in);
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close(sock_out);
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log("Protocol major versions differ for %s: %.200s vs. %.200s",
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get_remote_ipaddr(),
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server_version_string, client_version_string);
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fatal_cleanup();
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}
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if (compat20)
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packet_set_ssh2_format();
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}
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void
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destroy_sensitive_data(void)
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{
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/* Destroy the private and public keys. They will no longer be needed. */
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if (public_key)
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RSA_free(public_key);
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if (sensitive_data.private_key)
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RSA_free(sensitive_data.private_key);
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if (sensitive_data.host_key)
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RSA_free(sensitive_data.host_key);
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if (sensitive_data.dsa_host_key != NULL)
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key_free(sensitive_data.dsa_host_key);
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}
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/*
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* returns 1 if connection should be dropped, 0 otherwise.
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* dropping starts at connection #max_startups_begin with a probability
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* of (max_startups_rate/100). the probability increases linearly until
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* all connections are dropped for startups > max_startups
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*/
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int
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drop_connection(int startups)
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{
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double p, r;
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if (startups < options.max_startups_begin)
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return 0;
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if (startups >= options.max_startups)
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return 1;
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if (options.max_startups_rate == 100)
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return 1;
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p = 100 - options.max_startups_rate;
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p *= startups - options.max_startups_begin;
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p /= (double) (options.max_startups - options.max_startups_begin);
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p += options.max_startups_rate;
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p /= 100.0;
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r = arc4random() / (double) UINT_MAX;
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debug("drop_connection: p %g, r %g", p, r);
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return (r < p) ? 1 : 0;
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}
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int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
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int startup_pipe; /* in child */
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/*
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* Main program for the daemon.
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*/
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int
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main(int ac, char **av)
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{
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extern char *optarg;
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extern int optind;
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int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
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pid_t pid;
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socklen_t fromlen;
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int silent = 0;
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fd_set *fdset;
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struct sockaddr_storage from;
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const char *remote_ip;
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int remote_port;
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FILE *f;
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struct linger linger;
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struct addrinfo *ai;
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char ntop[NI_MAXHOST], strport[NI_MAXSERV];
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int listen_sock, maxfd;
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int startup_p[2];
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int startups = 0;
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init_rng();
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/* Save argv[0]. */
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saved_argc = ac;
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saved_argv = av;
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if (strchr(av[0], '/'))
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av0 = strrchr(av[0], '/') + 1;
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else
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av0 = av[0];
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/* Initialize configuration options to their default values. */
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initialize_server_options(&options);
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/* Parse command-line arguments. */
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while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:diqQ46")) != EOF) {
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switch (opt) {
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case '4':
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IPv4or6 = AF_INET;
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break;
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case '6':
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IPv4or6 = AF_INET6;
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break;
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case 'f':
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config_file_name = optarg;
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break;
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case 'd':
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if (0 == debug_flag) {
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debug_flag = 1;
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options.log_level = SYSLOG_LEVEL_DEBUG1;
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} else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
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options.log_level++;
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} else {
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|
fprintf(stderr, "Too high debugging level.\n");
|
|
exit(1);
|
|
}
|
|
break;
|
|
case 'i':
|
|
inetd_flag = 1;
|
|
break;
|
|
case 'Q':
|
|
silent = 1;
|
|
break;
|
|
case 'q':
|
|
options.log_level = SYSLOG_LEVEL_QUIET;
|
|
break;
|
|
case 'b':
|
|
options.server_key_bits = atoi(optarg);
|
|
break;
|
|
case 'p':
|
|
options.ports_from_cmdline = 1;
|
|
if (options.num_ports >= MAX_PORTS) {
|
|
fprintf(stderr, "too many ports.\n");
|
|
exit(1);
|
|
}
|
|
options.ports[options.num_ports++] = atoi(optarg);
|
|
break;
|
|
case 'g':
|
|
options.login_grace_time = atoi(optarg);
|
|
break;
|
|
case 'k':
|
|
options.key_regeneration_time = atoi(optarg);
|
|
break;
|
|
case 'h':
|
|
options.host_key_file = optarg;
|
|
break;
|
|
case 'V':
|
|
client_version_string = optarg;
|
|
/* only makes sense with inetd_flag, i.e. no listen() */
|
|
inetd_flag = 1;
|
|
break;
|
|
case 'u':
|
|
utmp_len = atoi(optarg);
|
|
break;
|
|
case '?':
|
|
default:
|
|
fprintf(stderr, "sshd version %s\n", SSH_VERSION);
|
|
fprintf(stderr, "Usage: %s [options]\n", av0);
|
|
fprintf(stderr, "Options:\n");
|
|
fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE);
|
|
fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
|
|
fprintf(stderr, " -i Started from inetd\n");
|
|
fprintf(stderr, " -q Quiet (no logging)\n");
|
|
fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
|
|
fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
|
|
fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n");
|
|
fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
|
|
fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
|
|
HOST_KEY_FILE);
|
|
fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
|
|
fprintf(stderr, " -4 Use IPv4 only\n");
|
|
fprintf(stderr, " -6 Use IPv6 only\n");
|
|
exit(1);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Force logging to stderr until we have loaded the private host
|
|
* key (unless started from inetd)
|
|
*/
|
|
log_init(av0,
|
|
options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
|
|
options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
|
|
!silent && !inetd_flag);
|
|
|
|
/* Read server configuration options from the configuration file. */
|
|
read_server_config(&options, config_file_name);
|
|
|
|
/* Fill in default values for those options not explicitly set. */
|
|
fill_default_server_options(&options);
|
|
|
|
/* Check that there are no remaining arguments. */
|
|
if (optind < ac) {
|
|
fprintf(stderr, "Extra argument %s.\n", av[optind]);
|
|
exit(1);
|
|
}
|
|
|
|
debug("sshd version %.100s", SSH_VERSION);
|
|
|
|
sensitive_data.dsa_host_key = NULL;
|
|
sensitive_data.host_key = NULL;
|
|
|
|
/* check if RSA support exists */
|
|
if ((options.protocol & SSH_PROTO_1) &&
|
|
rsa_alive() == 0) {
|
|
log("no RSA support in libssl and libcrypto. See ssl(8)");
|
|
log("Disabling protocol version 1");
|
|
options.protocol &= ~SSH_PROTO_1;
|
|
}
|
|
/* Load the RSA/DSA host key. It must have empty passphrase. */
|
|
if (options.protocol & SSH_PROTO_1) {
|
|
Key k;
|
|
sensitive_data.host_key = RSA_new();
|
|
k.type = KEY_RSA;
|
|
k.rsa = sensitive_data.host_key;
|
|
errno = 0;
|
|
if (!load_private_key(options.host_key_file, "", &k, NULL)) {
|
|
error("Could not load host key: %.200s: %.100s",
|
|
options.host_key_file, strerror(errno));
|
|
log("Disabling protocol version 1");
|
|
options.protocol &= ~SSH_PROTO_1;
|
|
}
|
|
k.rsa = NULL;
|
|
}
|
|
if (options.protocol & SSH_PROTO_2) {
|
|
sensitive_data.dsa_host_key = key_new(KEY_DSA);
|
|
if (!load_private_key(options.host_dsa_key_file, "", sensitive_data.dsa_host_key, NULL)) {
|
|
|
|
error("Could not load DSA host key: %.200s", options.host_dsa_key_file);
|
|
log("Disabling protocol version 2");
|
|
options.protocol &= ~SSH_PROTO_2;
|
|
}
|
|
}
|
|
if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) {
|
|
if (silent == 0)
|
|
fprintf(stderr, "sshd: no hostkeys available -- exiting.\n");
|
|
log("sshd: no hostkeys available -- exiting.\n");
|
|
exit(1);
|
|
}
|
|
|
|
/* Check certain values for sanity. */
|
|
if (options.protocol & SSH_PROTO_1) {
|
|
if (options.server_key_bits < 512 ||
|
|
options.server_key_bits > 32768) {
|
|
fprintf(stderr, "Bad server key size.\n");
|
|
exit(1);
|
|
}
|
|
/*
|
|
* Check that server and host key lengths differ sufficiently. This
|
|
* is necessary to make double encryption work with rsaref. Oh, I
|
|
* hate software patents. I dont know if this can go? Niels
|
|
*/
|
|
if (options.server_key_bits >
|
|
BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED &&
|
|
options.server_key_bits <
|
|
BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
|
|
options.server_key_bits =
|
|
BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED;
|
|
debug("Forcing server key to %d bits to make it differ from host key.",
|
|
options.server_key_bits);
|
|
}
|
|
}
|
|
|
|
#ifdef HAVE_SCO_PROTECTED_PW
|
|
(void) set_auth_parameters(ac, av);
|
|
#endif
|
|
|
|
/* Initialize the log (it is reinitialized below in case we forked). */
|
|
if (debug_flag && !inetd_flag)
|
|
log_stderr = 1;
|
|
log_init(av0, options.log_level, options.log_facility, log_stderr);
|
|
|
|
/*
|
|
* If not in debugging mode, and not started from inetd, disconnect
|
|
* from the controlling terminal, and fork. The original process
|
|
* exits.
|
|
*/
|
|
if (!debug_flag && !inetd_flag) {
|
|
#ifdef TIOCNOTTY
|
|
int fd;
|
|
#endif /* TIOCNOTTY */
|
|
if (daemon(0, 0) < 0)
|
|
fatal("daemon() failed: %.200s", strerror(errno));
|
|
|
|
/* Disconnect from the controlling tty. */
|
|
#ifdef TIOCNOTTY
|
|
fd = open("/dev/tty", O_RDWR | O_NOCTTY);
|
|
if (fd >= 0) {
|
|
(void) ioctl(fd, TIOCNOTTY, NULL);
|
|
close(fd);
|
|
}
|
|
#endif /* TIOCNOTTY */
|
|
}
|
|
/* Reinitialize the log (because of the fork above). */
|
|
log_init(av0, options.log_level, options.log_facility, log_stderr);
|
|
|
|
/* Do not display messages to stdout in RSA code. */
|
|
rsa_set_verbose(0);
|
|
|
|
/* Initialize the random number generator. */
|
|
arc4random_stir();
|
|
|
|
/* Chdir to the root directory so that the current disk can be
|
|
unmounted if desired. */
|
|
chdir("/");
|
|
|
|
/* Start listening for a socket, unless started from inetd. */
|
|
if (inetd_flag) {
|
|
int s1, s2;
|
|
s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
|
|
s2 = dup(s1);
|
|
sock_in = dup(0);
|
|
sock_out = dup(1);
|
|
startup_pipe = -1;
|
|
/*
|
|
* We intentionally do not close the descriptors 0, 1, and 2
|
|
* as our code for setting the descriptors won\'t work if
|
|
* ttyfd happens to be one of those.
|
|
*/
|
|
debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
|
|
|
|
if (options.protocol & SSH_PROTO_1) {
|
|
public_key = RSA_new();
|
|
sensitive_data.private_key = RSA_new();
|
|
log("Generating %d bit RSA key.", options.server_key_bits);
|
|
rsa_generate_key(sensitive_data.private_key, public_key,
|
|
options.server_key_bits);
|
|
arc4random_stir();
|
|
log("RSA key generation complete.");
|
|
}
|
|
} else {
|
|
for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
|
|
if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
|
|
continue;
|
|
if (num_listen_socks >= MAX_LISTEN_SOCKS)
|
|
fatal("Too many listen sockets. "
|
|
"Enlarge MAX_LISTEN_SOCKS");
|
|
if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
|
|
ntop, sizeof(ntop), strport, sizeof(strport),
|
|
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
|
|
error("getnameinfo failed");
|
|
continue;
|
|
}
|
|
/* Create socket for listening. */
|
|
listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
|
|
if (listen_sock < 0) {
|
|
/* kernel may not support ipv6 */
|
|
verbose("socket: %.100s", strerror(errno));
|
|
continue;
|
|
}
|
|
if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
|
|
error("listen_sock O_NONBLOCK: %s", strerror(errno));
|
|
close(listen_sock);
|
|
continue;
|
|
}
|
|
/*
|
|
* Set socket options. We try to make the port
|
|
* reusable and have it close as fast as possible
|
|
* without waiting in unnecessary wait states on
|
|
* close.
|
|
*/
|
|
setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
|
|
(void *) &on, sizeof(on));
|
|
linger.l_onoff = 1;
|
|
linger.l_linger = 5;
|
|
setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
|
|
(void *) &linger, sizeof(linger));
|
|
|
|
debug("Bind to port %s on %s.", strport, ntop);
|
|
|
|
/* Bind the socket to the desired port. */
|
|
if ((bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) &&
|
|
(!ai->ai_next)) {
|
|
error("Bind to port %s on %s failed: %.200s.",
|
|
strport, ntop, strerror(errno));
|
|
close(listen_sock);
|
|
continue;
|
|
}
|
|
listen_socks[num_listen_socks] = listen_sock;
|
|
num_listen_socks++;
|
|
|
|
/* Start listening on the port. */
|
|
log("Server listening on %s port %s.", ntop, strport);
|
|
if (listen(listen_sock, 5) < 0)
|
|
fatal("listen: %.100s", strerror(errno));
|
|
|
|
}
|
|
freeaddrinfo(options.listen_addrs);
|
|
|
|
if (!num_listen_socks)
|
|
fatal("Cannot bind any address.");
|
|
|
|
if (!debug_flag) {
|
|
/*
|
|
* Record our pid in /etc/sshd_pid to make it easier
|
|
* to kill the correct sshd. We don\'t want to do
|
|
* this before the bind above because the bind will
|
|
* fail if there already is a daemon, and this will
|
|
* overwrite any old pid in the file.
|
|
*/
|
|
f = fopen(options.pid_file, "wb");
|
|
if (f) {
|
|
fprintf(f, "%u\n", (unsigned int) getpid());
|
|
fclose(f);
|
|
}
|
|
}
|
|
if (options.protocol & SSH_PROTO_1) {
|
|
public_key = RSA_new();
|
|
sensitive_data.private_key = RSA_new();
|
|
|
|
log("Generating %d bit RSA key.", options.server_key_bits);
|
|
rsa_generate_key(sensitive_data.private_key, public_key,
|
|
options.server_key_bits);
|
|
arc4random_stir();
|
|
log("RSA key generation complete.");
|
|
|
|
/* Schedule server key regeneration alarm. */
|
|
signal(SIGALRM, key_regeneration_alarm);
|
|
alarm(options.key_regeneration_time);
|
|
}
|
|
|
|
/* Arrange to restart on SIGHUP. The handler needs listen_sock. */
|
|
signal(SIGHUP, sighup_handler);
|
|
|
|
signal(SIGTERM, sigterm_handler);
|
|
signal(SIGQUIT, sigterm_handler);
|
|
|
|
/* Arrange SIGCHLD to be caught. */
|
|
signal(SIGCHLD, main_sigchld_handler);
|
|
|
|
/* setup fd set for listen */
|
|
fdset = NULL;
|
|
maxfd = 0;
|
|
for (i = 0; i < num_listen_socks; i++)
|
|
if (listen_socks[i] > maxfd)
|
|
maxfd = listen_socks[i];
|
|
/* pipes connected to unauthenticated childs */
|
|
startup_pipes = xmalloc(options.max_startups * sizeof(int));
|
|
for (i = 0; i < options.max_startups; i++)
|
|
startup_pipes[i] = -1;
|
|
|
|
/*
|
|
* Stay listening for connections until the system crashes or
|
|
* the daemon is killed with a signal.
|
|
*/
|
|
for (;;) {
|
|
if (received_sighup)
|
|
sighup_restart();
|
|
if (fdset != NULL)
|
|
xfree(fdset);
|
|
fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask);
|
|
fdset = (fd_set *)xmalloc(fdsetsz);
|
|
memset(fdset, 0, fdsetsz);
|
|
|
|
for (i = 0; i < num_listen_socks; i++)
|
|
FD_SET(listen_socks[i], fdset);
|
|
for (i = 0; i < options.max_startups; i++)
|
|
if (startup_pipes[i] != -1)
|
|
FD_SET(startup_pipes[i], fdset);
|
|
|
|
/* Wait in select until there is a connection. */
|
|
if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) {
|
|
if (errno != EINTR)
|
|
error("select: %.100s", strerror(errno));
|
|
continue;
|
|
}
|
|
for (i = 0; i < options.max_startups; i++)
|
|
if (startup_pipes[i] != -1 &&
|
|
FD_ISSET(startup_pipes[i], fdset)) {
|
|
/*
|
|
* the read end of the pipe is ready
|
|
* if the child has closed the pipe
|
|
* after successfull authentication
|
|
* or if the child has died
|
|
*/
|
|
close(startup_pipes[i]);
|
|
startup_pipes[i] = -1;
|
|
startups--;
|
|
}
|
|
for (i = 0; i < num_listen_socks; i++) {
|
|
if (!FD_ISSET(listen_socks[i], fdset))
|
|
continue;
|
|
fromlen = sizeof(from);
|
|
newsock = accept(listen_socks[i], (struct sockaddr *)&from,
|
|
&fromlen);
|
|
if (newsock < 0) {
|
|
if (errno != EINTR && errno != EWOULDBLOCK)
|
|
error("accept: %.100s", strerror(errno));
|
|
continue;
|
|
}
|
|
if (fcntl(newsock, F_SETFL, 0) < 0) {
|
|
error("newsock del O_NONBLOCK: %s", strerror(errno));
|
|
continue;
|
|
}
|
|
if (drop_connection(startups) == 1) {
|
|
debug("drop connection #%d", startups);
|
|
close(newsock);
|
|
continue;
|
|
}
|
|
if (pipe(startup_p) == -1) {
|
|
close(newsock);
|
|
continue;
|
|
}
|
|
|
|
for (j = 0; j < options.max_startups; j++)
|
|
if (startup_pipes[j] == -1) {
|
|
startup_pipes[j] = startup_p[0];
|
|
if (maxfd < startup_p[0])
|
|
maxfd = startup_p[0];
|
|
startups++;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Got connection. Fork a child to handle it, unless
|
|
* we are in debugging mode.
|
|
*/
|
|
if (debug_flag) {
|
|
/*
|
|
* In debugging mode. Close the listening
|
|
* socket, and start processing the
|
|
* connection without forking.
|
|
*/
|
|
debug("Server will not fork when running in debugging mode.");
|
|
close_listen_socks();
|
|
sock_in = newsock;
|
|
sock_out = newsock;
|
|
startup_pipe = -1;
|
|
pid = getpid();
|
|
break;
|
|
} else {
|
|
/*
|
|
* Normal production daemon. Fork, and have
|
|
* the child process the connection. The
|
|
* parent continues listening.
|
|
*/
|
|
if ((pid = fork()) == 0) {
|
|
/*
|
|
* Child. Close the listening and max_startup
|
|
* sockets. Start using the accepted socket.
|
|
* Reinitialize logging (since our pid has
|
|
* changed). We break out of the loop to handle
|
|
* the connection.
|
|
*/
|
|
startup_pipe = startup_p[1];
|
|
for (j = 0; j < options.max_startups; j++)
|
|
if (startup_pipes[j] != -1)
|
|
close(startup_pipes[j]);
|
|
close_listen_socks();
|
|
sock_in = newsock;
|
|
sock_out = newsock;
|
|
log_init(av0, options.log_level, options.log_facility, log_stderr);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Parent. Stay in the loop. */
|
|
if (pid < 0)
|
|
error("fork: %.100s", strerror(errno));
|
|
else
|
|
debug("Forked child %d.", pid);
|
|
|
|
close(startup_p[1]);
|
|
|
|
/* Mark that the key has been used (it was "given" to the child). */
|
|
key_used = 1;
|
|
|
|
arc4random_stir();
|
|
|
|
/* Close the new socket (the child is now taking care of it). */
|
|
close(newsock);
|
|
}
|
|
/* child process check (or debug mode) */
|
|
if (num_listen_socks < 0)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* This is the child processing a new connection. */
|
|
|
|
/*
|
|
* Disable the key regeneration alarm. We will not regenerate the
|
|
* key since we are no longer in a position to give it to anyone. We
|
|
* will not restart on SIGHUP since it no longer makes sense.
|
|
*/
|
|
alarm(0);
|
|
signal(SIGALRM, SIG_DFL);
|
|
signal(SIGHUP, SIG_DFL);
|
|
signal(SIGTERM, SIG_DFL);
|
|
signal(SIGQUIT, SIG_DFL);
|
|
signal(SIGCHLD, SIG_DFL);
|
|
signal(SIGINT, SIG_DFL);
|
|
|
|
/*
|
|
* Set socket options for the connection. We want the socket to
|
|
* close as fast as possible without waiting for anything. If the
|
|
* connection is not a socket, these will do nothing.
|
|
*/
|
|
/* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
|
|
linger.l_onoff = 1;
|
|
linger.l_linger = 5;
|
|
setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
|
|
|
|
/*
|
|
* Register our connection. This turns encryption off because we do
|
|
* not have a key.
|
|
*/
|
|
packet_set_connection(sock_in, sock_out);
|
|
|
|
remote_port = get_remote_port();
|
|
remote_ip = get_remote_ipaddr();
|
|
|
|
/* Check whether logins are denied from this host. */
|
|
#ifdef LIBWRAP
|
|
/* XXX LIBWRAP noes not know about IPv6 */
|
|
{
|
|
struct request_info req;
|
|
|
|
request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL);
|
|
fromhost(&req);
|
|
|
|
if (!hosts_access(&req)) {
|
|
close(sock_in);
|
|
close(sock_out);
|
|
refuse(&req);
|
|
}
|
|
/*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
|
|
}
|
|
#endif /* LIBWRAP */
|
|
/* Log the connection. */
|
|
verbose("Connection from %.500s port %d", remote_ip, remote_port);
|
|
|
|
/*
|
|
* We don\'t want to listen forever unless the other side
|
|
* successfully authenticates itself. So we set up an alarm which is
|
|
* cleared after successful authentication. A limit of zero
|
|
* indicates no limit. Note that we don\'t set the alarm in debugging
|
|
* mode; it is just annoying to have the server exit just when you
|
|
* are about to discover the bug.
|
|
*/
|
|
signal(SIGALRM, grace_alarm_handler);
|
|
if (!debug_flag)
|
|
alarm(options.login_grace_time);
|
|
|
|
sshd_exchange_identification(sock_in, sock_out);
|
|
/*
|
|
* Check that the connection comes from a privileged port. Rhosts-
|
|
* and Rhosts-RSA-Authentication only make sense from priviledged
|
|
* programs. Of course, if the intruder has root access on his local
|
|
* machine, he can connect from any port. So do not use these
|
|
* authentication methods from machines that you do not trust.
|
|
*/
|
|
if (remote_port >= IPPORT_RESERVED ||
|
|
remote_port < IPPORT_RESERVED / 2) {
|
|
options.rhosts_authentication = 0;
|
|
options.rhosts_rsa_authentication = 0;
|
|
}
|
|
#ifdef KRB4
|
|
if (!packet_connection_is_ipv4() &&
|
|
options.kerberos_authentication) {
|
|
debug("Kerberos Authentication disabled, only available for IPv4.");
|
|
options.kerberos_authentication = 0;
|
|
}
|
|
#endif /* KRB4 */
|
|
|
|
packet_set_nonblocking();
|
|
|
|
/* perform the key exchange */
|
|
/* authenticate user and start session */
|
|
if (compat20) {
|
|
do_ssh2_kex();
|
|
do_authentication2();
|
|
} else {
|
|
do_ssh1_kex();
|
|
do_authentication();
|
|
}
|
|
|
|
#ifdef KRB4
|
|
/* Cleanup user's ticket cache file. */
|
|
if (options.kerberos_ticket_cleanup)
|
|
(void) dest_tkt();
|
|
#endif /* KRB4 */
|
|
|
|
/* The connection has been terminated. */
|
|
verbose("Closing connection to %.100s", remote_ip);
|
|
|
|
#ifdef USE_PAM
|
|
finish_pam();
|
|
#endif /* USE_PAM */
|
|
|
|
packet_close();
|
|
exit(0);
|
|
}
|
|
|
|
/*
|
|
* SSH1 key exchange
|
|
*/
|
|
void
|
|
do_ssh1_kex()
|
|
{
|
|
int i, len;
|
|
int plen, slen;
|
|
BIGNUM *session_key_int;
|
|
unsigned char session_key[SSH_SESSION_KEY_LENGTH];
|
|
unsigned char cookie[8];
|
|
unsigned int cipher_type, auth_mask, protocol_flags;
|
|
u_int32_t rand = 0;
|
|
|
|
/*
|
|
* Generate check bytes that the client must send back in the user
|
|
* packet in order for it to be accepted; this is used to defy ip
|
|
* spoofing attacks. Note that this only works against somebody
|
|
* doing IP spoofing from a remote machine; any machine on the local
|
|
* network can still see outgoing packets and catch the random
|
|
* cookie. This only affects rhosts authentication, and this is one
|
|
* of the reasons why it is inherently insecure.
|
|
*/
|
|
for (i = 0; i < 8; i++) {
|
|
if (i % 4 == 0)
|
|
rand = arc4random();
|
|
cookie[i] = rand & 0xff;
|
|
rand >>= 8;
|
|
}
|
|
|
|
/*
|
|
* Send our public key. We include in the packet 64 bits of random
|
|
* data that must be matched in the reply in order to prevent IP
|
|
* spoofing.
|
|
*/
|
|
packet_start(SSH_SMSG_PUBLIC_KEY);
|
|
for (i = 0; i < 8; i++)
|
|
packet_put_char(cookie[i]);
|
|
|
|
/* Store our public server RSA key. */
|
|
packet_put_int(BN_num_bits(public_key->n));
|
|
packet_put_bignum(public_key->e);
|
|
packet_put_bignum(public_key->n);
|
|
|
|
/* Store our public host RSA key. */
|
|
packet_put_int(BN_num_bits(sensitive_data.host_key->n));
|
|
packet_put_bignum(sensitive_data.host_key->e);
|
|
packet_put_bignum(sensitive_data.host_key->n);
|
|
|
|
/* Put protocol flags. */
|
|
packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
|
|
|
|
/* Declare which ciphers we support. */
|
|
packet_put_int(cipher_mask_ssh1(0));
|
|
|
|
/* Declare supported authentication types. */
|
|
auth_mask = 0;
|
|
if (options.rhosts_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_RHOSTS;
|
|
if (options.rhosts_rsa_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
|
|
if (options.rsa_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_RSA;
|
|
#ifdef KRB4
|
|
if (options.kerberos_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_KERBEROS;
|
|
#endif
|
|
#ifdef AFS
|
|
if (options.kerberos_tgt_passing)
|
|
auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
|
|
if (options.afs_token_passing)
|
|
auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
|
|
#endif
|
|
#ifdef SKEY
|
|
if (options.skey_authentication == 1)
|
|
auth_mask |= 1 << SSH_AUTH_TIS;
|
|
#endif
|
|
if (options.password_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_PASSWORD;
|
|
packet_put_int(auth_mask);
|
|
|
|
/* Send the packet and wait for it to be sent. */
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
debug("Sent %d bit public key and %d bit host key.",
|
|
BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n));
|
|
|
|
/* Read clients reply (cipher type and session key). */
|
|
packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
|
|
|
|
/* Get cipher type and check whether we accept this. */
|
|
cipher_type = packet_get_char();
|
|
|
|
if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
|
|
packet_disconnect("Warning: client selects unsupported cipher.");
|
|
|
|
/* Get check bytes from the packet. These must match those we
|
|
sent earlier with the public key packet. */
|
|
for (i = 0; i < 8; i++)
|
|
if (cookie[i] != packet_get_char())
|
|
packet_disconnect("IP Spoofing check bytes do not match.");
|
|
|
|
debug("Encryption type: %.200s", cipher_name(cipher_type));
|
|
|
|
/* Get the encrypted integer. */
|
|
session_key_int = BN_new();
|
|
packet_get_bignum(session_key_int, &slen);
|
|
|
|
protocol_flags = packet_get_int();
|
|
packet_set_protocol_flags(protocol_flags);
|
|
|
|
packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
|
|
|
|
/*
|
|
* Decrypt it using our private server key and private host key (key
|
|
* with larger modulus first).
|
|
*/
|
|
if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) {
|
|
/* Private key has bigger modulus. */
|
|
if (BN_num_bits(sensitive_data.private_key->n) <
|
|
BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
|
|
fatal("do_connection: %s: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
|
|
get_remote_ipaddr(),
|
|
BN_num_bits(sensitive_data.private_key->n),
|
|
BN_num_bits(sensitive_data.host_key->n),
|
|
SSH_KEY_BITS_RESERVED);
|
|
}
|
|
rsa_private_decrypt(session_key_int, session_key_int,
|
|
sensitive_data.private_key);
|
|
rsa_private_decrypt(session_key_int, session_key_int,
|
|
sensitive_data.host_key);
|
|
} else {
|
|
/* Host key has bigger modulus (or they are equal). */
|
|
if (BN_num_bits(sensitive_data.host_key->n) <
|
|
BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) {
|
|
fatal("do_connection: %s: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d",
|
|
get_remote_ipaddr(),
|
|
BN_num_bits(sensitive_data.host_key->n),
|
|
BN_num_bits(sensitive_data.private_key->n),
|
|
SSH_KEY_BITS_RESERVED);
|
|
}
|
|
rsa_private_decrypt(session_key_int, session_key_int,
|
|
sensitive_data.host_key);
|
|
rsa_private_decrypt(session_key_int, session_key_int,
|
|
sensitive_data.private_key);
|
|
}
|
|
|
|
compute_session_id(session_id, cookie,
|
|
sensitive_data.host_key->n,
|
|
sensitive_data.private_key->n);
|
|
|
|
/* Destroy the private and public keys. They will no longer be needed. */
|
|
destroy_sensitive_data();
|
|
|
|
/*
|
|
* Extract session key from the decrypted integer. The key is in the
|
|
* least significant 256 bits of the integer; the first byte of the
|
|
* key is in the highest bits.
|
|
*/
|
|
BN_mask_bits(session_key_int, sizeof(session_key) * 8);
|
|
len = BN_num_bytes(session_key_int);
|
|
if (len < 0 || len > sizeof(session_key))
|
|
fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d",
|
|
get_remote_ipaddr(),
|
|
len, (int) sizeof(session_key));
|
|
memset(session_key, 0, sizeof(session_key));
|
|
BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len);
|
|
|
|
/* Destroy the decrypted integer. It is no longer needed. */
|
|
BN_clear_free(session_key_int);
|
|
|
|
/* Xor the first 16 bytes of the session key with the session id. */
|
|
for (i = 0; i < 16; i++)
|
|
session_key[i] ^= session_id[i];
|
|
|
|
/* Set the session key. From this on all communications will be encrypted. */
|
|
packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
|
|
|
|
/* Destroy our copy of the session key. It is no longer needed. */
|
|
memset(session_key, 0, sizeof(session_key));
|
|
|
|
debug("Received session key; encryption turned on.");
|
|
|
|
/* Send an acknowledgement packet. Note that this packet is sent encrypted. */
|
|
packet_start(SSH_SMSG_SUCCESS);
|
|
packet_send();
|
|
packet_write_wait();
|
|
}
|
|
|
|
/*
|
|
* SSH2 key exchange: diffie-hellman-group1-sha1
|
|
*/
|
|
void
|
|
do_ssh2_kex()
|
|
{
|
|
Buffer *server_kexinit;
|
|
Buffer *client_kexinit;
|
|
int payload_len;
|
|
int i;
|
|
Kex *kex;
|
|
char *cprop[PROPOSAL_MAX];
|
|
|
|
/* KEXINIT */
|
|
|
|
if (options.ciphers != NULL) {
|
|
myproposal[PROPOSAL_ENC_ALGS_CTOS] =
|
|
myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
|
|
}
|
|
server_kexinit = kex_init(myproposal);
|
|
client_kexinit = xmalloc(sizeof(*client_kexinit));
|
|
buffer_init(client_kexinit);
|
|
|
|
/* algorithm negotiation */
|
|
kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
|
|
kex = kex_choose_conf(cprop, myproposal, 1);
|
|
for (i = 0; i < PROPOSAL_MAX; i++)
|
|
xfree(cprop[i]);
|
|
|
|
switch (kex->kex_type) {
|
|
case DH_GRP1_SHA1:
|
|
ssh_dh1_server(kex, client_kexinit, server_kexinit);
|
|
break;
|
|
case DH_GEX_SHA1:
|
|
ssh_dhgex_server(kex, client_kexinit, server_kexinit);
|
|
break;
|
|
default:
|
|
fatal("Unsupported key exchange %d", kex->kex_type);
|
|
}
|
|
|
|
debug("send SSH2_MSG_NEWKEYS.");
|
|
packet_start(SSH2_MSG_NEWKEYS);
|
|
packet_send();
|
|
packet_write_wait();
|
|
debug("done: send SSH2_MSG_NEWKEYS.");
|
|
|
|
debug("Wait SSH2_MSG_NEWKEYS.");
|
|
packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
|
|
debug("GOT SSH2_MSG_NEWKEYS.");
|
|
|
|
#ifdef DEBUG_KEXDH
|
|
/* send 1st encrypted/maced/compressed message */
|
|
packet_start(SSH2_MSG_IGNORE);
|
|
packet_put_cstring("markus");
|
|
packet_send();
|
|
packet_write_wait();
|
|
#endif
|
|
|
|
debug("done: KEX2.");
|
|
}
|
|
|
|
/*
|
|
* SSH2 key exchange
|
|
*/
|
|
|
|
/* diffie-hellman-group1-sha1 */
|
|
|
|
void
|
|
ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
|
|
{
|
|
#ifdef DEBUG_KEXDH
|
|
int i;
|
|
#endif
|
|
int payload_len, dlen;
|
|
int slen;
|
|
unsigned char *signature = NULL;
|
|
unsigned char *server_host_key_blob = NULL;
|
|
unsigned int sbloblen;
|
|
unsigned int klen, kout;
|
|
unsigned char *kbuf;
|
|
unsigned char *hash;
|
|
BIGNUM *shared_secret = 0;
|
|
DH *dh;
|
|
BIGNUM *dh_client_pub = 0;
|
|
|
|
/* KEXDH */
|
|
debug("Wait SSH2_MSG_KEXDH_INIT.");
|
|
packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
|
|
|
|
/* key, cert */
|
|
dh_client_pub = BN_new();
|
|
if (dh_client_pub == NULL)
|
|
fatal("dh_client_pub == NULL");
|
|
packet_get_bignum2(dh_client_pub, &dlen);
|
|
|
|
#ifdef DEBUG_KEXDH
|
|
fprintf(stderr, "\ndh_client_pub= ");
|
|
BN_print_fp(stderr, dh_client_pub);
|
|
fprintf(stderr, "\n");
|
|
debug("bits %d", BN_num_bits(dh_client_pub));
|
|
#endif
|
|
|
|
/* generate DH key */
|
|
dh = dh_new_group1(); /* XXX depends on 'kex' */
|
|
|
|
#ifdef DEBUG_KEXDH
|
|
fprintf(stderr, "\np= ");
|
|
BN_print_fp(stderr, dh->p);
|
|
fprintf(stderr, "\ng= ");
|
|
bn_print(dh->g);
|
|
fprintf(stderr, "\npub= ");
|
|
BN_print_fp(stderr, dh->pub_key);
|
|
fprintf(stderr, "\n");
|
|
DHparams_print_fp(stderr, dh);
|
|
#endif
|
|
if (!dh_pub_is_valid(dh, dh_client_pub))
|
|
packet_disconnect("bad client public DH value");
|
|
|
|
klen = DH_size(dh);
|
|
kbuf = xmalloc(klen);
|
|
kout = DH_compute_key(kbuf, dh_client_pub, dh);
|
|
|
|
#ifdef DEBUG_KEXDH
|
|
debug("shared secret: len %d/%d", klen, kout);
|
|
fprintf(stderr, "shared secret == ");
|
|
for (i = 0; i< kout; i++)
|
|
fprintf(stderr, "%02x", (kbuf[i])&0xff);
|
|
fprintf(stderr, "\n");
|
|
#endif
|
|
shared_secret = BN_new();
|
|
|
|
BN_bin2bn(kbuf, kout, shared_secret);
|
|
memset(kbuf, 0, klen);
|
|
xfree(kbuf);
|
|
|
|
/* XXX precompute? */
|
|
dsa_make_key_blob(sensitive_data.dsa_host_key,
|
|
&server_host_key_blob, &sbloblen);
|
|
|
|
/* calc H */ /* XXX depends on 'kex' */
|
|
hash = kex_hash(
|
|
client_version_string,
|
|
server_version_string,
|
|
buffer_ptr(client_kexinit), buffer_len(client_kexinit),
|
|
buffer_ptr(server_kexinit), buffer_len(server_kexinit),
|
|
(char *)server_host_key_blob, sbloblen,
|
|
dh_client_pub,
|
|
dh->pub_key,
|
|
shared_secret
|
|
);
|
|
buffer_free(client_kexinit);
|
|
buffer_free(server_kexinit);
|
|
xfree(client_kexinit);
|
|
xfree(server_kexinit);
|
|
#ifdef DEBUG_KEXDH
|
|
fprintf(stderr, "hash == ");
|
|
for (i = 0; i< 20; i++)
|
|
fprintf(stderr, "%02x", (hash[i])&0xff);
|
|
fprintf(stderr, "\n");
|
|
#endif
|
|
/* save session id := H */
|
|
/* XXX hashlen depends on KEX */
|
|
session_id2_len = 20;
|
|
session_id2 = xmalloc(session_id2_len);
|
|
memcpy(session_id2, hash, session_id2_len);
|
|
|
|
/* sign H */
|
|
/* XXX hashlen depends on KEX */
|
|
dsa_sign(sensitive_data.dsa_host_key, &signature, &slen, hash, 20);
|
|
|
|
destroy_sensitive_data();
|
|
|
|
/* send server hostkey, DH pubkey 'f' and singed H */
|
|
packet_start(SSH2_MSG_KEXDH_REPLY);
|
|
packet_put_string((char *)server_host_key_blob, sbloblen);
|
|
packet_put_bignum2(dh->pub_key); /* f */
|
|
packet_put_string((char *)signature, slen);
|
|
packet_send();
|
|
xfree(signature);
|
|
xfree(server_host_key_blob);
|
|
packet_write_wait();
|
|
|
|
kex_derive_keys(kex, hash, shared_secret);
|
|
packet_set_kex(kex);
|
|
|
|
/* have keys, free DH */
|
|
DH_free(dh);
|
|
}
|
|
|
|
/* diffie-hellman-group-exchange-sha1 */
|
|
|
|
void
|
|
ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
|
|
{
|
|
#ifdef DEBUG_KEXDH
|
|
int i;
|
|
#endif
|
|
int payload_len, dlen;
|
|
int slen, nbits;
|
|
unsigned char *signature = NULL;
|
|
unsigned char *server_host_key_blob = NULL;
|
|
unsigned int sbloblen;
|
|
unsigned int klen, kout;
|
|
unsigned char *kbuf;
|
|
unsigned char *hash;
|
|
BIGNUM *shared_secret = 0;
|
|
DH *dh;
|
|
BIGNUM *dh_client_pub = 0;
|
|
|
|
/* KEXDHGEX */
|
|
debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
|
|
packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST);
|
|
nbits = packet_get_int();
|
|
dh = choose_dh(nbits);
|
|
|
|
debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
|
|
packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
|
|
packet_put_bignum2(dh->p);
|
|
packet_put_bignum2(dh->g);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
|
|
packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT);
|
|
|
|
/* key, cert */
|
|
dh_client_pub = BN_new();
|
|
if (dh_client_pub == NULL)
|
|
fatal("dh_client_pub == NULL");
|
|
packet_get_bignum2(dh_client_pub, &dlen);
|
|
|
|
#ifdef DEBUG_KEXDH
|
|
fprintf(stderr, "\ndh_client_pub= ");
|
|
BN_print_fp(stderr, dh_client_pub);
|
|
fprintf(stderr, "\n");
|
|
debug("bits %d", BN_num_bits(dh_client_pub));
|
|
#endif
|
|
|
|
#ifdef DEBUG_KEXDH
|
|
fprintf(stderr, "\np= ");
|
|
BN_print_fp(stderr, dh->p);
|
|
fprintf(stderr, "\ng= ");
|
|
bn_print(dh->g);
|
|
fprintf(stderr, "\npub= ");
|
|
BN_print_fp(stderr, dh->pub_key);
|
|
fprintf(stderr, "\n");
|
|
DHparams_print_fp(stderr, dh);
|
|
#endif
|
|
if (!dh_pub_is_valid(dh, dh_client_pub))
|
|
packet_disconnect("bad client public DH value");
|
|
|
|
klen = DH_size(dh);
|
|
kbuf = xmalloc(klen);
|
|
kout = DH_compute_key(kbuf, dh_client_pub, dh);
|
|
|
|
#ifdef DEBUG_KEXDH
|
|
debug("shared secret: len %d/%d", klen, kout);
|
|
fprintf(stderr, "shared secret == ");
|
|
for (i = 0; i< kout; i++)
|
|
fprintf(stderr, "%02x", (kbuf[i])&0xff);
|
|
fprintf(stderr, "\n");
|
|
#endif
|
|
shared_secret = BN_new();
|
|
|
|
BN_bin2bn(kbuf, kout, shared_secret);
|
|
memset(kbuf, 0, klen);
|
|
xfree(kbuf);
|
|
|
|
/* XXX precompute? */
|
|
dsa_make_key_blob(sensitive_data.dsa_host_key,
|
|
&server_host_key_blob, &sbloblen);
|
|
|
|
/* calc H */ /* XXX depends on 'kex' */
|
|
hash = kex_hash_gex(
|
|
client_version_string,
|
|
server_version_string,
|
|
buffer_ptr(client_kexinit), buffer_len(client_kexinit),
|
|
buffer_ptr(server_kexinit), buffer_len(server_kexinit),
|
|
(char *)server_host_key_blob, sbloblen,
|
|
nbits, dh->p, dh->g,
|
|
dh_client_pub,
|
|
dh->pub_key,
|
|
shared_secret
|
|
);
|
|
buffer_free(client_kexinit);
|
|
buffer_free(server_kexinit);
|
|
xfree(client_kexinit);
|
|
xfree(server_kexinit);
|
|
#ifdef DEBUG_KEXDH
|
|
fprintf(stderr, "hash == ");
|
|
for (i = 0; i< 20; i++)
|
|
fprintf(stderr, "%02x", (hash[i])&0xff);
|
|
fprintf(stderr, "\n");
|
|
#endif
|
|
/* save session id := H */
|
|
/* XXX hashlen depends on KEX */
|
|
session_id2_len = 20;
|
|
session_id2 = xmalloc(session_id2_len);
|
|
memcpy(session_id2, hash, session_id2_len);
|
|
|
|
/* sign H */
|
|
/* XXX hashlen depends on KEX */
|
|
dsa_sign(sensitive_data.dsa_host_key, &signature, &slen, hash, 20);
|
|
|
|
destroy_sensitive_data();
|
|
|
|
/* send server hostkey, DH pubkey 'f' and singed H */
|
|
packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
|
|
packet_put_string((char *)server_host_key_blob, sbloblen);
|
|
packet_put_bignum2(dh->pub_key); /* f */
|
|
packet_put_string((char *)signature, slen);
|
|
packet_send();
|
|
xfree(signature);
|
|
xfree(server_host_key_blob);
|
|
packet_write_wait();
|
|
|
|
kex_derive_keys(kex, hash, shared_secret);
|
|
packet_set_kex(kex);
|
|
|
|
/* have keys, free DH */
|
|
DH_free(dh);
|
|
}
|
|
|