Local changes introduced an OPENSSH_VERSION macro, but this conflicts with a macro of the same name introduced with OpenSSL 1.1.1.
2428 lines
64 KiB
C
2428 lines
64 KiB
C
/* $OpenBSD: sshd.c,v 1.514 2018/08/13 02:41:05 djm Exp $ */
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/*
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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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* Privilege Separation:
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*
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* Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
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* Copyright (c) 2002 Niels Provos. 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("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/socket.h>
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#ifdef HAVE_SYS_STAT_H
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# include <sys/stat.h>
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#endif
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#ifdef HAVE_SYS_TIME_H
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# include <sys/time.h>
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#endif
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#include "openbsd-compat/sys-tree.h"
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#include "openbsd-compat/sys-queue.h"
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#include <sys/wait.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <netdb.h>
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#ifdef HAVE_PATHS_H
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#include <paths.h>
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#endif
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#include <grp.h>
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#include <pwd.h>
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#include <signal.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <limits.h>
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#ifdef WITH_OPENSSL
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#include <openssl/dh.h>
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#include <openssl/bn.h>
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#include <openssl/rand.h>
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#include "openbsd-compat/openssl-compat.h"
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#endif
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#ifdef HAVE_SECUREWARE
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#include <sys/security.h>
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#include <prot.h>
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#endif
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#ifdef __FreeBSD__
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#include <resolv.h>
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#if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
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#include <gssapi/gssapi.h>
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#elif defined(GSSAPI) && defined(HAVE_GSSAPI_H)
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#include <gssapi.h>
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#endif
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#endif
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#include "xmalloc.h"
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#include "ssh.h"
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#include "ssh2.h"
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#include "sshpty.h"
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#include "packet.h"
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#include "log.h"
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#include "sshbuf.h"
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#include "misc.h"
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#include "match.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 "cipher.h"
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#include "digest.h"
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#include "sshkey.h"
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#include "kex.h"
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#include "myproposal.h"
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#include "authfile.h"
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#include "pathnames.h"
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#include "atomicio.h"
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#include "canohost.h"
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#include "hostfile.h"
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#include "auth.h"
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#include "authfd.h"
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#include "msg.h"
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#include "dispatch.h"
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#include "channels.h"
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#include "session.h"
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#include "monitor.h"
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#ifdef GSSAPI
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#include "ssh-gss.h"
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#endif
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#include "monitor_wrap.h"
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#include "ssh-sandbox.h"
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#include "auth-options.h"
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#include "version.h"
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#include "ssherr.h"
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#include "blacklist_client.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;
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int deny_severity;
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#endif /* LIBWRAP */
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/* Re-exec fds */
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#define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
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#define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
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#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
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#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
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extern char *__progname;
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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 = _PATH_SERVER_CONFIG_FILE;
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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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/*
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* Indicating that the daemon should only test the configuration and keys.
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* If test_flag > 1 ("-T" flag), then sshd will also dump the effective
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* configuration, optionally using connection information provided by the
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* "-C" flag.
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*/
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int test_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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/* Flag indicating that sshd should not detach and become a daemon. */
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int no_daemon_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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/* Saved arguments to main(). */
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char **saved_argv;
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int saved_argc;
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/* re-exec */
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int rexeced_flag = 0;
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int rexec_flag = 1;
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int rexec_argc = 0;
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char **rexec_argv;
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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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/* Daemon's agent connection */
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int auth_sock = -1;
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int have_agent = 0;
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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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struct sshkey **host_keys; /* all private host keys */
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struct sshkey **host_pubkeys; /* all public host keys */
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struct sshkey **host_certificates; /* all public host certificates */
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int have_ssh2_key;
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} sensitive_data;
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/* This is set to true when a signal is received. */
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static volatile sig_atomic_t received_sighup = 0;
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static volatile sig_atomic_t received_sigterm = 0;
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/* session identifier, used by RSA-auth */
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u_char session_id[16];
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/* same for ssh2 */
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u_char *session_id2 = NULL;
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u_int session_id2_len = 0;
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/* record remote hostname or ip */
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u_int utmp_len = HOST_NAME_MAX+1;
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/* options.max_startup sized array of fd ints */
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int *startup_pipes = NULL;
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int startup_pipe; /* in child */
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/* variables used for privilege separation */
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int use_privsep = -1;
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struct monitor *pmonitor = NULL;
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int privsep_is_preauth = 1;
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static int privsep_chroot = 1;
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/* global authentication context */
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Authctxt *the_authctxt = NULL;
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/* global key/cert auth options. XXX move to permanent ssh->authctxt? */
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struct sshauthopt *auth_opts = NULL;
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/* sshd_config buffer */
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struct sshbuf *cfg;
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/* message to be displayed after login */
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struct sshbuf *loginmsg;
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/* Unprivileged user */
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struct passwd *privsep_pw = NULL;
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/* Prototypes for various functions defined later in this file. */
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void destroy_sensitive_data(void);
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void demote_sensitive_data(void);
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static void do_ssh2_kex(void);
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/*
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* Close all listening sockets
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*/
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static 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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static void
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close_startup_pipes(void)
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{
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int i;
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if (startup_pipes)
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for (i = 0; i < options.max_startups; i++)
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if (startup_pipes[i] != -1)
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close(startup_pipes[i]);
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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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/*ARGSUSED*/
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static void
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sighup_handler(int sig)
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{
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int save_errno = errno;
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received_sighup = 1;
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errno = save_errno;
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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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static void
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sighup_restart(void)
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{
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logit("Received SIGHUP; restarting.");
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if (options.pid_file != NULL)
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unlink(options.pid_file);
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platform_pre_restart();
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close_listen_socks();
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close_startup_pipes();
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alarm(0); /* alarm timer persists across exec */
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signal(SIGHUP, SIG_IGN); /* will be restored after exec */
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execv(saved_argv[0], saved_argv);
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logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
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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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*/
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/*ARGSUSED*/
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static void
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sigterm_handler(int sig)
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{
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received_sigterm = sig;
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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 children.
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*/
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/*ARGSUSED*/
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static 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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pid_t pid;
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int status;
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while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
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(pid < 0 && errno == EINTR))
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;
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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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/*ARGSUSED*/
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static void
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grace_alarm_handler(int sig)
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{
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if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
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kill(pmonitor->m_pid, SIGALRM);
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/*
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* Try to kill any processes that we have spawned, E.g. authorized
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* keys command helpers.
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*/
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if (getpgid(0) == getpid()) {
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signal(SIGTERM, SIG_IGN);
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kill(0, SIGTERM);
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}
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BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh");
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/* Log error and exit. */
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sigdie("Timeout before authentication for %s port %d",
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ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
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}
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static void
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sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
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{
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u_int i;
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int remote_major, remote_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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xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n",
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PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
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*options.version_addendum == '\0' ? "" : " ",
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options.version_addendum);
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/* Send our protocol version identification. */
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if (atomicio(vwrite, sock_out, server_version_string,
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strlen(server_version_string))
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!= strlen(server_version_string)) {
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logit("Could not write ident string to %s port %d",
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
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cleanup_exit(255);
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}
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/* Read other sides version identification. */
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memset(buf, 0, sizeof(buf));
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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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logit("Did not receive identification string "
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"from %s port %d",
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
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cleanup_exit(255);
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}
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if (buf[i] == '\r') {
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buf[i] = 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] = 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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* 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(vwrite, sock_out, s, strlen(s));
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logit("Bad protocol version identification '%.100s' "
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"from %s port %d", client_version_string,
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
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close(sock_in);
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close(sock_out);
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cleanup_exit(255);
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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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ssh->compat = compat_datafellows(remote_version);
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if ((ssh->compat & SSH_BUG_PROBE) != 0) {
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logit("probed from %s port %d with %s. Don't panic.",
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
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client_version_string);
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cleanup_exit(255);
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}
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if ((ssh->compat & SSH_BUG_SCANNER) != 0) {
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logit("scanned from %s port %d with %s. Don't panic.",
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
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client_version_string);
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cleanup_exit(255);
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}
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if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
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logit("Client version \"%.100s\" uses unsafe RSA signature "
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"scheme; disabling use of RSA keys", remote_version);
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}
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chop(server_version_string);
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debug("Local version string %.200s", server_version_string);
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if (remote_major != 2 &&
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!(remote_major == 1 && remote_minor == 99)) {
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s = "Protocol major versions differ.\n";
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(void) atomicio(vwrite, sock_out, s, strlen(s));
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close(sock_in);
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close(sock_out);
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logit("Protocol major versions differ for %s port %d: "
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"%.200s vs. %.200s",
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ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
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server_version_string, client_version_string);
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cleanup_exit(255);
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}
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}
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|
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/* Destroy the host and server keys. They will no longer be needed. */
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void
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destroy_sensitive_data(void)
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{
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u_int i;
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for (i = 0; i < options.num_host_key_files; i++) {
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if (sensitive_data.host_keys[i]) {
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sshkey_free(sensitive_data.host_keys[i]);
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sensitive_data.host_keys[i] = NULL;
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}
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if (sensitive_data.host_certificates[i]) {
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sshkey_free(sensitive_data.host_certificates[i]);
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sensitive_data.host_certificates[i] = NULL;
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}
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}
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}
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|
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/* Demote private to public keys for network child */
|
|
void
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demote_sensitive_data(void)
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{
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struct sshkey *tmp;
|
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u_int i;
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int r;
|
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|
|
for (i = 0; i < options.num_host_key_files; i++) {
|
|
if (sensitive_data.host_keys[i]) {
|
|
if ((r = sshkey_demote(sensitive_data.host_keys[i],
|
|
&tmp)) != 0)
|
|
fatal("could not demote host %s key: %s",
|
|
sshkey_type(sensitive_data.host_keys[i]),
|
|
ssh_err(r));
|
|
sshkey_free(sensitive_data.host_keys[i]);
|
|
sensitive_data.host_keys[i] = tmp;
|
|
}
|
|
/* Certs do not need demotion */
|
|
}
|
|
}
|
|
|
|
static void
|
|
reseed_prngs(void)
|
|
{
|
|
u_int32_t rnd[256];
|
|
|
|
#ifdef WITH_OPENSSL
|
|
RAND_poll();
|
|
#endif
|
|
arc4random_stir(); /* noop on recent arc4random() implementations */
|
|
arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
|
|
|
|
#ifdef WITH_OPENSSL
|
|
RAND_seed(rnd, sizeof(rnd));
|
|
/* give libcrypto a chance to notice the PID change */
|
|
if ((RAND_bytes((u_char *)rnd, 1)) != 1)
|
|
fatal("%s: RAND_bytes failed", __func__);
|
|
#endif
|
|
|
|
explicit_bzero(rnd, sizeof(rnd));
|
|
}
|
|
|
|
static void
|
|
privsep_preauth_child(void)
|
|
{
|
|
gid_t gidset[1];
|
|
|
|
/* Enable challenge-response authentication for privilege separation */
|
|
privsep_challenge_enable();
|
|
|
|
#ifdef GSSAPI
|
|
/* Cache supported mechanism OIDs for later use */
|
|
if (options.gss_authentication)
|
|
ssh_gssapi_prepare_supported_oids();
|
|
#endif
|
|
|
|
reseed_prngs();
|
|
|
|
/* Demote the private keys to public keys. */
|
|
demote_sensitive_data();
|
|
|
|
/* Demote the child */
|
|
if (privsep_chroot) {
|
|
/* Change our root directory */
|
|
if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
|
|
fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
|
|
strerror(errno));
|
|
if (chdir("/") == -1)
|
|
fatal("chdir(\"/\"): %s", strerror(errno));
|
|
|
|
/* Drop our privileges */
|
|
debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
|
|
(u_int)privsep_pw->pw_gid);
|
|
gidset[0] = privsep_pw->pw_gid;
|
|
if (setgroups(1, gidset) < 0)
|
|
fatal("setgroups: %.100s", strerror(errno));
|
|
permanently_set_uid(privsep_pw);
|
|
}
|
|
}
|
|
|
|
static int
|
|
privsep_preauth(Authctxt *authctxt)
|
|
{
|
|
int status, r;
|
|
pid_t pid;
|
|
struct ssh_sandbox *box = NULL;
|
|
|
|
/* Set up unprivileged child process to deal with network data */
|
|
pmonitor = monitor_init();
|
|
/* Store a pointer to the kex for later rekeying */
|
|
pmonitor->m_pkex = &active_state->kex;
|
|
|
|
if (use_privsep == PRIVSEP_ON)
|
|
box = ssh_sandbox_init(pmonitor);
|
|
pid = fork();
|
|
if (pid == -1) {
|
|
fatal("fork of unprivileged child failed");
|
|
} else if (pid != 0) {
|
|
debug2("Network child is on pid %ld", (long)pid);
|
|
|
|
pmonitor->m_pid = pid;
|
|
if (have_agent) {
|
|
r = ssh_get_authentication_socket(&auth_sock);
|
|
if (r != 0) {
|
|
error("Could not get agent socket: %s",
|
|
ssh_err(r));
|
|
have_agent = 0;
|
|
}
|
|
}
|
|
if (box != NULL)
|
|
ssh_sandbox_parent_preauth(box, pid);
|
|
monitor_child_preauth(authctxt, pmonitor);
|
|
|
|
/* Wait for the child's exit status */
|
|
while (waitpid(pid, &status, 0) < 0) {
|
|
if (errno == EINTR)
|
|
continue;
|
|
pmonitor->m_pid = -1;
|
|
fatal("%s: waitpid: %s", __func__, strerror(errno));
|
|
}
|
|
privsep_is_preauth = 0;
|
|
pmonitor->m_pid = -1;
|
|
if (WIFEXITED(status)) {
|
|
if (WEXITSTATUS(status) != 0)
|
|
fatal("%s: preauth child exited with status %d",
|
|
__func__, WEXITSTATUS(status));
|
|
} else if (WIFSIGNALED(status))
|
|
fatal("%s: preauth child terminated by signal %d",
|
|
__func__, WTERMSIG(status));
|
|
if (box != NULL)
|
|
ssh_sandbox_parent_finish(box);
|
|
return 1;
|
|
} else {
|
|
/* child */
|
|
close(pmonitor->m_sendfd);
|
|
close(pmonitor->m_log_recvfd);
|
|
|
|
/* Arrange for logging to be sent to the monitor */
|
|
set_log_handler(mm_log_handler, pmonitor);
|
|
|
|
privsep_preauth_child();
|
|
setproctitle("%s", "[net]");
|
|
if (box != NULL)
|
|
ssh_sandbox_child(box);
|
|
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
static void
|
|
privsep_postauth(Authctxt *authctxt)
|
|
{
|
|
#ifdef DISABLE_FD_PASSING
|
|
if (1) {
|
|
#else
|
|
if (authctxt->pw->pw_uid == 0) {
|
|
#endif
|
|
/* File descriptor passing is broken or root login */
|
|
use_privsep = 0;
|
|
goto skip;
|
|
}
|
|
|
|
/* New socket pair */
|
|
monitor_reinit(pmonitor);
|
|
|
|
pmonitor->m_pid = fork();
|
|
if (pmonitor->m_pid == -1)
|
|
fatal("fork of unprivileged child failed");
|
|
else if (pmonitor->m_pid != 0) {
|
|
verbose("User child is on pid %ld", (long)pmonitor->m_pid);
|
|
sshbuf_reset(loginmsg);
|
|
monitor_clear_keystate(pmonitor);
|
|
monitor_child_postauth(pmonitor);
|
|
|
|
/* NEVERREACHED */
|
|
exit(0);
|
|
}
|
|
|
|
/* child */
|
|
|
|
close(pmonitor->m_sendfd);
|
|
pmonitor->m_sendfd = -1;
|
|
|
|
/* Demote the private keys to public keys. */
|
|
demote_sensitive_data();
|
|
|
|
reseed_prngs();
|
|
|
|
/* Drop privileges */
|
|
do_setusercontext(authctxt->pw);
|
|
|
|
skip:
|
|
/* It is safe now to apply the key state */
|
|
monitor_apply_keystate(pmonitor);
|
|
|
|
/*
|
|
* Tell the packet layer that authentication was successful, since
|
|
* this information is not part of the key state.
|
|
*/
|
|
packet_set_authenticated();
|
|
}
|
|
|
|
static void
|
|
append_hostkey_type(struct sshbuf *b, const char *s)
|
|
{
|
|
int r;
|
|
|
|
if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
|
|
debug3("%s: %s key not permitted by HostkeyAlgorithms",
|
|
__func__, s);
|
|
return;
|
|
}
|
|
if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
|
|
fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r));
|
|
}
|
|
|
|
static char *
|
|
list_hostkey_types(void)
|
|
{
|
|
struct sshbuf *b;
|
|
struct sshkey *key;
|
|
char *ret;
|
|
u_int i;
|
|
|
|
if ((b = sshbuf_new()) == NULL)
|
|
fatal("%s: sshbuf_new failed", __func__);
|
|
for (i = 0; i < options.num_host_key_files; i++) {
|
|
key = sensitive_data.host_keys[i];
|
|
if (key == NULL)
|
|
key = sensitive_data.host_pubkeys[i];
|
|
if (key == NULL)
|
|
continue;
|
|
switch (key->type) {
|
|
case KEY_RSA:
|
|
/* for RSA we also support SHA2 signatures */
|
|
append_hostkey_type(b, "rsa-sha2-512");
|
|
append_hostkey_type(b, "rsa-sha2-256");
|
|
/* FALLTHROUGH */
|
|
case KEY_DSA:
|
|
case KEY_ECDSA:
|
|
case KEY_ED25519:
|
|
case KEY_XMSS:
|
|
append_hostkey_type(b, sshkey_ssh_name(key));
|
|
break;
|
|
}
|
|
/* If the private key has a cert peer, then list that too */
|
|
key = sensitive_data.host_certificates[i];
|
|
if (key == NULL)
|
|
continue;
|
|
switch (key->type) {
|
|
case KEY_RSA_CERT:
|
|
/* for RSA we also support SHA2 signatures */
|
|
append_hostkey_type(b,
|
|
"rsa-sha2-512-cert-v01@openssh.com");
|
|
append_hostkey_type(b,
|
|
"rsa-sha2-256-cert-v01@openssh.com");
|
|
/* FALLTHROUGH */
|
|
case KEY_DSA_CERT:
|
|
case KEY_ECDSA_CERT:
|
|
case KEY_ED25519_CERT:
|
|
case KEY_XMSS_CERT:
|
|
append_hostkey_type(b, sshkey_ssh_name(key));
|
|
break;
|
|
}
|
|
}
|
|
if ((ret = sshbuf_dup_string(b)) == NULL)
|
|
fatal("%s: sshbuf_dup_string failed", __func__);
|
|
sshbuf_free(b);
|
|
debug("%s: %s", __func__, ret);
|
|
return ret;
|
|
}
|
|
|
|
static struct sshkey *
|
|
get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
|
|
{
|
|
u_int i;
|
|
struct sshkey *key;
|
|
|
|
for (i = 0; i < options.num_host_key_files; i++) {
|
|
switch (type) {
|
|
case KEY_RSA_CERT:
|
|
case KEY_DSA_CERT:
|
|
case KEY_ECDSA_CERT:
|
|
case KEY_ED25519_CERT:
|
|
case KEY_XMSS_CERT:
|
|
key = sensitive_data.host_certificates[i];
|
|
break;
|
|
default:
|
|
key = sensitive_data.host_keys[i];
|
|
if (key == NULL && !need_private)
|
|
key = sensitive_data.host_pubkeys[i];
|
|
break;
|
|
}
|
|
if (key != NULL && key->type == type &&
|
|
(key->type != KEY_ECDSA || key->ecdsa_nid == nid))
|
|
return need_private ?
|
|
sensitive_data.host_keys[i] : key;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
struct sshkey *
|
|
get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
|
|
{
|
|
return get_hostkey_by_type(type, nid, 0, ssh);
|
|
}
|
|
|
|
struct sshkey *
|
|
get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
|
|
{
|
|
return get_hostkey_by_type(type, nid, 1, ssh);
|
|
}
|
|
|
|
struct sshkey *
|
|
get_hostkey_by_index(int ind)
|
|
{
|
|
if (ind < 0 || (u_int)ind >= options.num_host_key_files)
|
|
return (NULL);
|
|
return (sensitive_data.host_keys[ind]);
|
|
}
|
|
|
|
struct sshkey *
|
|
get_hostkey_public_by_index(int ind, struct ssh *ssh)
|
|
{
|
|
if (ind < 0 || (u_int)ind >= options.num_host_key_files)
|
|
return (NULL);
|
|
return (sensitive_data.host_pubkeys[ind]);
|
|
}
|
|
|
|
int
|
|
get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
|
|
{
|
|
u_int i;
|
|
|
|
for (i = 0; i < options.num_host_key_files; i++) {
|
|
if (sshkey_is_cert(key)) {
|
|
if (key == sensitive_data.host_certificates[i] ||
|
|
(compare && sensitive_data.host_certificates[i] &&
|
|
sshkey_equal(key,
|
|
sensitive_data.host_certificates[i])))
|
|
return (i);
|
|
} else {
|
|
if (key == sensitive_data.host_keys[i] ||
|
|
(compare && sensitive_data.host_keys[i] &&
|
|
sshkey_equal(key, sensitive_data.host_keys[i])))
|
|
return (i);
|
|
if (key == sensitive_data.host_pubkeys[i] ||
|
|
(compare && sensitive_data.host_pubkeys[i] &&
|
|
sshkey_equal(key, sensitive_data.host_pubkeys[i])))
|
|
return (i);
|
|
}
|
|
}
|
|
return (-1);
|
|
}
|
|
|
|
/* Inform the client of all hostkeys */
|
|
static void
|
|
notify_hostkeys(struct ssh *ssh)
|
|
{
|
|
struct sshbuf *buf;
|
|
struct sshkey *key;
|
|
u_int i, nkeys;
|
|
int r;
|
|
char *fp;
|
|
|
|
/* Some clients cannot cope with the hostkeys message, skip those. */
|
|
if (datafellows & SSH_BUG_HOSTKEYS)
|
|
return;
|
|
|
|
if ((buf = sshbuf_new()) == NULL)
|
|
fatal("%s: sshbuf_new", __func__);
|
|
for (i = nkeys = 0; i < options.num_host_key_files; i++) {
|
|
key = get_hostkey_public_by_index(i, ssh);
|
|
if (key == NULL || key->type == KEY_UNSPEC ||
|
|
sshkey_is_cert(key))
|
|
continue;
|
|
fp = sshkey_fingerprint(key, options.fingerprint_hash,
|
|
SSH_FP_DEFAULT);
|
|
debug3("%s: key %d: %s %s", __func__, i,
|
|
sshkey_ssh_name(key), fp);
|
|
free(fp);
|
|
if (nkeys == 0) {
|
|
packet_start(SSH2_MSG_GLOBAL_REQUEST);
|
|
packet_put_cstring("hostkeys-00@openssh.com");
|
|
packet_put_char(0); /* want-reply */
|
|
}
|
|
sshbuf_reset(buf);
|
|
if ((r = sshkey_putb(key, buf)) != 0)
|
|
fatal("%s: couldn't put hostkey %d: %s",
|
|
__func__, i, ssh_err(r));
|
|
packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
|
|
nkeys++;
|
|
}
|
|
debug3("%s: sent %u hostkeys", __func__, nkeys);
|
|
if (nkeys == 0)
|
|
fatal("%s: no hostkeys", __func__);
|
|
packet_send();
|
|
sshbuf_free(buf);
|
|
}
|
|
|
|
/*
|
|
* returns 1 if connection should be dropped, 0 otherwise.
|
|
* dropping starts at connection #max_startups_begin with a probability
|
|
* of (max_startups_rate/100). the probability increases linearly until
|
|
* all connections are dropped for startups > max_startups
|
|
*/
|
|
static int
|
|
drop_connection(int startups)
|
|
{
|
|
int p, r;
|
|
|
|
if (startups < options.max_startups_begin)
|
|
return 0;
|
|
if (startups >= options.max_startups)
|
|
return 1;
|
|
if (options.max_startups_rate == 100)
|
|
return 1;
|
|
|
|
p = 100 - options.max_startups_rate;
|
|
p *= startups - options.max_startups_begin;
|
|
p /= options.max_startups - options.max_startups_begin;
|
|
p += options.max_startups_rate;
|
|
r = arc4random_uniform(100);
|
|
|
|
debug("drop_connection: p %d, r %d", p, r);
|
|
return (r < p) ? 1 : 0;
|
|
}
|
|
|
|
static void
|
|
usage(void)
|
|
{
|
|
if (options.version_addendum && *options.version_addendum != '\0')
|
|
fprintf(stderr, "%s %s, %s\n",
|
|
SSH_RELEASE,
|
|
options.version_addendum, OPENSSL_VERSION_STRING);
|
|
else
|
|
fprintf(stderr, "%s, %s\n",
|
|
SSH_RELEASE, OPENSSL_VERSION_STRING);
|
|
fprintf(stderr,
|
|
"usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
|
|
" [-E log_file] [-f config_file] [-g login_grace_time]\n"
|
|
" [-h host_key_file] [-o option] [-p port] [-u len]\n"
|
|
);
|
|
exit(1);
|
|
}
|
|
|
|
static void
|
|
send_rexec_state(int fd, struct sshbuf *conf)
|
|
{
|
|
struct sshbuf *m;
|
|
int r;
|
|
|
|
debug3("%s: entering fd = %d config len %zu", __func__, fd,
|
|
sshbuf_len(conf));
|
|
|
|
/*
|
|
* Protocol from reexec master to child:
|
|
* string configuration
|
|
* string rngseed (only if OpenSSL is not self-seeded)
|
|
*/
|
|
if ((m = sshbuf_new()) == NULL)
|
|
fatal("%s: sshbuf_new failed", __func__);
|
|
if ((r = sshbuf_put_stringb(m, conf)) != 0)
|
|
fatal("%s: buffer error: %s", __func__, ssh_err(r));
|
|
|
|
#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
|
|
rexec_send_rng_seed(m);
|
|
#endif
|
|
|
|
if (ssh_msg_send(fd, 0, m) == -1)
|
|
fatal("%s: ssh_msg_send failed", __func__);
|
|
|
|
sshbuf_free(m);
|
|
|
|
debug3("%s: done", __func__);
|
|
}
|
|
|
|
static void
|
|
recv_rexec_state(int fd, struct sshbuf *conf)
|
|
{
|
|
struct sshbuf *m;
|
|
u_char *cp, ver;
|
|
size_t len;
|
|
int r;
|
|
|
|
debug3("%s: entering fd = %d", __func__, fd);
|
|
|
|
if ((m = sshbuf_new()) == NULL)
|
|
fatal("%s: sshbuf_new failed", __func__);
|
|
if (ssh_msg_recv(fd, m) == -1)
|
|
fatal("%s: ssh_msg_recv failed", __func__);
|
|
if ((r = sshbuf_get_u8(m, &ver)) != 0)
|
|
fatal("%s: buffer error: %s", __func__, ssh_err(r));
|
|
if (ver != 0)
|
|
fatal("%s: rexec version mismatch", __func__);
|
|
if ((r = sshbuf_get_string(m, &cp, &len)) != 0)
|
|
fatal("%s: buffer error: %s", __func__, ssh_err(r));
|
|
if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
|
|
fatal("%s: buffer error: %s", __func__, ssh_err(r));
|
|
#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
|
|
rexec_recv_rng_seed(m);
|
|
#endif
|
|
|
|
free(cp);
|
|
sshbuf_free(m);
|
|
|
|
debug3("%s: done", __func__);
|
|
}
|
|
|
|
/* Accept a connection from inetd */
|
|
static void
|
|
server_accept_inetd(int *sock_in, int *sock_out)
|
|
{
|
|
int fd;
|
|
|
|
startup_pipe = -1;
|
|
if (rexeced_flag) {
|
|
close(REEXEC_CONFIG_PASS_FD);
|
|
*sock_in = *sock_out = dup(STDIN_FILENO);
|
|
if (!debug_flag) {
|
|
startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
|
|
close(REEXEC_STARTUP_PIPE_FD);
|
|
}
|
|
} else {
|
|
*sock_in = dup(STDIN_FILENO);
|
|
*sock_out = dup(STDOUT_FILENO);
|
|
}
|
|
/*
|
|
* 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.
|
|
*/
|
|
if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
|
|
dup2(fd, STDIN_FILENO);
|
|
dup2(fd, STDOUT_FILENO);
|
|
if (!log_stderr)
|
|
dup2(fd, STDERR_FILENO);
|
|
if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
|
|
close(fd);
|
|
}
|
|
debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
|
|
}
|
|
|
|
/*
|
|
* Listen for TCP connections
|
|
*/
|
|
static void
|
|
listen_on_addrs(struct listenaddr *la)
|
|
{
|
|
int ret, listen_sock;
|
|
struct addrinfo *ai;
|
|
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
|
|
int socksize;
|
|
socklen_t len;
|
|
|
|
for (ai = la->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 ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
|
|
ntop, sizeof(ntop), strport, sizeof(strport),
|
|
NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
|
|
error("getnameinfo failed: %.100s",
|
|
ssh_gai_strerror(ret));
|
|
continue;
|
|
}
|
|
/* Create socket for listening. */
|
|
listen_sock = socket(ai->ai_family, ai->ai_socktype,
|
|
ai->ai_protocol);
|
|
if (listen_sock < 0) {
|
|
/* kernel may not support ipv6 */
|
|
verbose("socket: %.100s", strerror(errno));
|
|
continue;
|
|
}
|
|
if (set_nonblock(listen_sock) == -1) {
|
|
close(listen_sock);
|
|
continue;
|
|
}
|
|
if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
|
|
verbose("socket: CLOEXEC: %s", strerror(errno));
|
|
close(listen_sock);
|
|
continue;
|
|
}
|
|
/* Socket options */
|
|
set_reuseaddr(listen_sock);
|
|
if (la->rdomain != NULL &&
|
|
set_rdomain(listen_sock, la->rdomain) == -1) {
|
|
close(listen_sock);
|
|
continue;
|
|
}
|
|
|
|
/* Only communicate in IPv6 over AF_INET6 sockets. */
|
|
if (ai->ai_family == AF_INET6)
|
|
sock_set_v6only(listen_sock);
|
|
|
|
debug("Bind to port %s on %s.", strport, ntop);
|
|
|
|
len = sizeof(socksize);
|
|
getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len);
|
|
debug("Server TCP RWIN socket size: %d", socksize);
|
|
|
|
/* Bind the socket to the desired port. */
|
|
if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
|
|
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. */
|
|
if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
|
|
fatal("listen on [%s]:%s: %.100s",
|
|
ntop, strport, strerror(errno));
|
|
logit("Server listening on %s port %s%s%s.",
|
|
ntop, strport,
|
|
la->rdomain == NULL ? "" : " rdomain ",
|
|
la->rdomain == NULL ? "" : la->rdomain);
|
|
}
|
|
}
|
|
|
|
static void
|
|
server_listen(void)
|
|
{
|
|
u_int i;
|
|
|
|
for (i = 0; i < options.num_listen_addrs; i++) {
|
|
listen_on_addrs(&options.listen_addrs[i]);
|
|
freeaddrinfo(options.listen_addrs[i].addrs);
|
|
free(options.listen_addrs[i].rdomain);
|
|
memset(&options.listen_addrs[i], 0,
|
|
sizeof(options.listen_addrs[i]));
|
|
}
|
|
free(options.listen_addrs);
|
|
options.listen_addrs = NULL;
|
|
options.num_listen_addrs = 0;
|
|
|
|
if (!num_listen_socks)
|
|
fatal("Cannot bind any address.");
|
|
}
|
|
|
|
/*
|
|
* The main TCP accept loop. Note that, for the non-debug case, returns
|
|
* from this function are in a forked subprocess.
|
|
*/
|
|
static void
|
|
server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
|
|
{
|
|
fd_set *fdset;
|
|
int i, j, ret, maxfd;
|
|
int startups = 0;
|
|
int startup_p[2] = { -1 , -1 };
|
|
struct sockaddr_storage from;
|
|
socklen_t fromlen;
|
|
pid_t pid;
|
|
u_char rnd[256];
|
|
|
|
/* setup fd set for accept */
|
|
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 = xcalloc(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();
|
|
free(fdset);
|
|
fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
|
|
sizeof(fd_mask));
|
|
|
|
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. */
|
|
ret = select(maxfd+1, fdset, NULL, NULL, NULL);
|
|
if (ret < 0 && errno != EINTR)
|
|
error("select: %.100s", strerror(errno));
|
|
if (received_sigterm) {
|
|
logit("Received signal %d; terminating.",
|
|
(int) received_sigterm);
|
|
close_listen_socks();
|
|
if (options.pid_file != NULL)
|
|
unlink(options.pid_file);
|
|
exit(received_sigterm == SIGTERM ? 0 : 255);
|
|
}
|
|
if (ret < 0)
|
|
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 successful 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 &&
|
|
errno != ECONNABORTED && errno != EAGAIN)
|
|
error("accept: %.100s",
|
|
strerror(errno));
|
|
if (errno == EMFILE || errno == ENFILE)
|
|
usleep(100 * 1000);
|
|
continue;
|
|
}
|
|
if (unset_nonblock(*newsock) == -1) {
|
|
close(*newsock);
|
|
continue;
|
|
}
|
|
if (drop_connection(startups) == 1) {
|
|
char *laddr = get_local_ipaddr(*newsock);
|
|
char *raddr = get_peer_ipaddr(*newsock);
|
|
|
|
verbose("drop connection #%d from [%s]:%d "
|
|
"on [%s]:%d past MaxStartups", startups,
|
|
raddr, get_peer_port(*newsock),
|
|
laddr, get_local_port(*newsock));
|
|
free(laddr);
|
|
free(raddr);
|
|
close(*newsock);
|
|
continue;
|
|
}
|
|
if (pipe(startup_p) == -1) {
|
|
close(*newsock);
|
|
continue;
|
|
}
|
|
|
|
if (rexec_flag && socketpair(AF_UNIX,
|
|
SOCK_STREAM, 0, config_s) == -1) {
|
|
error("reexec socketpair: %s",
|
|
strerror(errno));
|
|
close(*newsock);
|
|
close(startup_p[0]);
|
|
close(startup_p[1]);
|
|
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;
|
|
close(startup_p[0]);
|
|
close(startup_p[1]);
|
|
startup_pipe = -1;
|
|
pid = getpid();
|
|
if (rexec_flag) {
|
|
send_rexec_state(config_s[0], cfg);
|
|
close(config_s[0]);
|
|
}
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Normal production daemon. Fork, and have
|
|
* the child process the connection. The
|
|
* parent continues listening.
|
|
*/
|
|
platform_pre_fork();
|
|
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.
|
|
*/
|
|
platform_post_fork_child();
|
|
startup_pipe = startup_p[1];
|
|
close_startup_pipes();
|
|
close_listen_socks();
|
|
*sock_in = *newsock;
|
|
*sock_out = *newsock;
|
|
log_init(__progname,
|
|
options.log_level,
|
|
options.log_facility,
|
|
log_stderr);
|
|
if (rexec_flag)
|
|
close(config_s[0]);
|
|
break;
|
|
}
|
|
|
|
/* Parent. Stay in the loop. */
|
|
platform_post_fork_parent(pid);
|
|
if (pid < 0)
|
|
error("fork: %.100s", strerror(errno));
|
|
else
|
|
debug("Forked child %ld.", (long)pid);
|
|
|
|
close(startup_p[1]);
|
|
|
|
if (rexec_flag) {
|
|
send_rexec_state(config_s[0], cfg);
|
|
close(config_s[0]);
|
|
close(config_s[1]);
|
|
}
|
|
close(*newsock);
|
|
|
|
/*
|
|
* Ensure that our random state differs
|
|
* from that of the child
|
|
*/
|
|
arc4random_stir();
|
|
arc4random_buf(rnd, sizeof(rnd));
|
|
#ifdef WITH_OPENSSL
|
|
RAND_seed(rnd, sizeof(rnd));
|
|
if ((RAND_bytes((u_char *)rnd, 1)) != 1)
|
|
fatal("%s: RAND_bytes failed", __func__);
|
|
#endif
|
|
explicit_bzero(rnd, sizeof(rnd));
|
|
}
|
|
|
|
/* child process check (or debug mode) */
|
|
if (num_listen_socks < 0)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If IP options are supported, make sure there are none (log and
|
|
* return an error if any are found). Basically we are worried about
|
|
* source routing; it can be used to pretend you are somebody
|
|
* (ip-address) you are not. That itself may be "almost acceptable"
|
|
* under certain circumstances, but rhosts authentication is useless
|
|
* if source routing is accepted. Notice also that if we just dropped
|
|
* source routing here, the other side could use IP spoofing to do
|
|
* rest of the interaction and could still bypass security. So we
|
|
* exit here if we detect any IP options.
|
|
*/
|
|
static void
|
|
check_ip_options(struct ssh *ssh)
|
|
{
|
|
#ifdef IP_OPTIONS
|
|
int sock_in = ssh_packet_get_connection_in(ssh);
|
|
struct sockaddr_storage from;
|
|
u_char opts[200];
|
|
socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
|
|
char text[sizeof(opts) * 3 + 1];
|
|
|
|
memset(&from, 0, sizeof(from));
|
|
if (getpeername(sock_in, (struct sockaddr *)&from,
|
|
&fromlen) < 0)
|
|
return;
|
|
if (from.ss_family != AF_INET)
|
|
return;
|
|
/* XXX IPv6 options? */
|
|
|
|
if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
|
|
&option_size) >= 0 && option_size != 0) {
|
|
text[0] = '\0';
|
|
for (i = 0; i < option_size; i++)
|
|
snprintf(text + i*3, sizeof(text) - i*3,
|
|
" %2.2x", opts[i]);
|
|
fatal("Connection from %.100s port %d with IP opts: %.800s",
|
|
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
|
|
}
|
|
return;
|
|
#endif /* IP_OPTIONS */
|
|
}
|
|
|
|
/* Set the routing domain for this process */
|
|
static void
|
|
set_process_rdomain(struct ssh *ssh, const char *name)
|
|
{
|
|
#if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
|
|
if (name == NULL)
|
|
return; /* default */
|
|
|
|
if (strcmp(name, "%D") == 0) {
|
|
/* "expands" to routing domain of connection */
|
|
if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
|
|
return;
|
|
}
|
|
/* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
|
|
return sys_set_process_rdomain(name);
|
|
#elif defined(__OpenBSD__)
|
|
int rtable, ortable = getrtable();
|
|
const char *errstr;
|
|
|
|
if (name == NULL)
|
|
return; /* default */
|
|
|
|
if (strcmp(name, "%D") == 0) {
|
|
/* "expands" to routing domain of connection */
|
|
if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
|
|
return;
|
|
}
|
|
|
|
rtable = (int)strtonum(name, 0, 255, &errstr);
|
|
if (errstr != NULL) /* Shouldn't happen */
|
|
fatal("Invalid routing domain \"%s\": %s", name, errstr);
|
|
if (rtable != ortable && setrtable(rtable) != 0)
|
|
fatal("Unable to set routing domain %d: %s",
|
|
rtable, strerror(errno));
|
|
debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable);
|
|
#else /* defined(__OpenBSD__) */
|
|
fatal("Unable to set routing domain: not supported in this platform");
|
|
#endif
|
|
}
|
|
|
|
static void
|
|
accumulate_host_timing_secret(struct sshbuf *server_cfg,
|
|
const struct sshkey *key)
|
|
{
|
|
static struct ssh_digest_ctx *ctx;
|
|
u_char *hash;
|
|
size_t len;
|
|
struct sshbuf *buf;
|
|
int r;
|
|
|
|
if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL)
|
|
fatal("%s: ssh_digest_start", __func__);
|
|
if (key == NULL) { /* finalize */
|
|
/* add server config in case we are using agent for host keys */
|
|
if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg),
|
|
sshbuf_len(server_cfg)) != 0)
|
|
fatal("%s: ssh_digest_update", __func__);
|
|
len = ssh_digest_bytes(SSH_DIGEST_SHA512);
|
|
hash = xmalloc(len);
|
|
if (ssh_digest_final(ctx, hash, len) != 0)
|
|
fatal("%s: ssh_digest_final", __func__);
|
|
options.timing_secret = PEEK_U64(hash);
|
|
freezero(hash, len);
|
|
ssh_digest_free(ctx);
|
|
ctx = NULL;
|
|
return;
|
|
}
|
|
if ((buf = sshbuf_new()) == NULL)
|
|
fatal("%s could not allocate buffer", __func__);
|
|
if ((r = sshkey_private_serialize(key, buf)) != 0)
|
|
fatal("sshkey_private_serialize: %s", ssh_err(r));
|
|
if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0)
|
|
fatal("%s: ssh_digest_update", __func__);
|
|
sshbuf_reset(buf);
|
|
sshbuf_free(buf);
|
|
}
|
|
|
|
/*
|
|
* Main program for the daemon.
|
|
*/
|
|
int
|
|
main(int ac, char **av)
|
|
{
|
|
struct ssh *ssh = NULL;
|
|
extern char *optarg;
|
|
extern int optind;
|
|
int r, opt, on = 1, already_daemon, remote_port;
|
|
int sock_in = -1, sock_out = -1, newsock = -1;
|
|
const char *remote_ip, *rdomain;
|
|
char *fp, *line, *laddr, *logfile = NULL;
|
|
int config_s[2] = { -1 , -1 };
|
|
u_int i, j;
|
|
u_int64_t ibytes, obytes;
|
|
mode_t new_umask;
|
|
struct sshkey *key;
|
|
struct sshkey *pubkey;
|
|
int keytype;
|
|
Authctxt *authctxt;
|
|
struct connection_info *connection_info = NULL;
|
|
|
|
ssh_malloc_init(); /* must be called before any mallocs */
|
|
|
|
#ifdef HAVE_SECUREWARE
|
|
(void)set_auth_parameters(ac, av);
|
|
#endif
|
|
__progname = ssh_get_progname(av[0]);
|
|
|
|
/* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
|
|
saved_argc = ac;
|
|
rexec_argc = ac;
|
|
saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
|
|
for (i = 0; (int)i < ac; i++)
|
|
saved_argv[i] = xstrdup(av[i]);
|
|
saved_argv[i] = NULL;
|
|
|
|
#ifndef HAVE_SETPROCTITLE
|
|
/* Prepare for later setproctitle emulation */
|
|
compat_init_setproctitle(ac, av);
|
|
av = saved_argv;
|
|
#endif
|
|
|
|
if (geteuid() == 0 && setgroups(0, NULL) == -1)
|
|
debug("setgroups(): %.200s", strerror(errno));
|
|
|
|
/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
|
|
sanitise_stdfd();
|
|
|
|
/* Initialize configuration options to their default values. */
|
|
initialize_server_options(&options);
|
|
|
|
/* Parse command-line arguments. */
|
|
while ((opt = getopt(ac, av,
|
|
"C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
|
|
switch (opt) {
|
|
case '4':
|
|
options.address_family = AF_INET;
|
|
break;
|
|
case '6':
|
|
options.address_family = AF_INET6;
|
|
break;
|
|
case 'f':
|
|
config_file_name = optarg;
|
|
break;
|
|
case 'c':
|
|
servconf_add_hostcert("[command-line]", 0,
|
|
&options, optarg);
|
|
break;
|
|
case 'd':
|
|
if (debug_flag == 0) {
|
|
debug_flag = 1;
|
|
options.log_level = SYSLOG_LEVEL_DEBUG1;
|
|
} else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
|
|
options.log_level++;
|
|
break;
|
|
case 'D':
|
|
no_daemon_flag = 1;
|
|
break;
|
|
case 'E':
|
|
logfile = optarg;
|
|
/* FALLTHROUGH */
|
|
case 'e':
|
|
log_stderr = 1;
|
|
break;
|
|
case 'i':
|
|
inetd_flag = 1;
|
|
break;
|
|
case 'r':
|
|
rexec_flag = 0;
|
|
break;
|
|
case 'R':
|
|
rexeced_flag = 1;
|
|
inetd_flag = 1;
|
|
break;
|
|
case 'Q':
|
|
/* ignored */
|
|
break;
|
|
case 'q':
|
|
options.log_level = SYSLOG_LEVEL_QUIET;
|
|
break;
|
|
case 'b':
|
|
/* protocol 1, ignored */
|
|
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++] = a2port(optarg);
|
|
if (options.ports[options.num_ports-1] <= 0) {
|
|
fprintf(stderr, "Bad port number.\n");
|
|
exit(1);
|
|
}
|
|
break;
|
|
case 'g':
|
|
if ((options.login_grace_time = convtime(optarg)) == -1) {
|
|
fprintf(stderr, "Invalid login grace time.\n");
|
|
exit(1);
|
|
}
|
|
break;
|
|
case 'k':
|
|
/* protocol 1, ignored */
|
|
break;
|
|
case 'h':
|
|
servconf_add_hostkey("[command-line]", 0,
|
|
&options, optarg);
|
|
break;
|
|
case 't':
|
|
test_flag = 1;
|
|
break;
|
|
case 'T':
|
|
test_flag = 2;
|
|
break;
|
|
case 'C':
|
|
connection_info = get_connection_info(0, 0);
|
|
if (parse_server_match_testspec(connection_info,
|
|
optarg) == -1)
|
|
exit(1);
|
|
break;
|
|
case 'u':
|
|
utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
|
|
if (utmp_len > HOST_NAME_MAX+1) {
|
|
fprintf(stderr, "Invalid utmp length.\n");
|
|
exit(1);
|
|
}
|
|
break;
|
|
case 'o':
|
|
line = xstrdup(optarg);
|
|
if (process_server_config_line(&options, line,
|
|
"command-line", 0, NULL, NULL) != 0)
|
|
exit(1);
|
|
free(line);
|
|
break;
|
|
case '?':
|
|
default:
|
|
usage();
|
|
break;
|
|
}
|
|
}
|
|
if (rexeced_flag || inetd_flag)
|
|
rexec_flag = 0;
|
|
if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
|
|
fatal("sshd re-exec requires execution with an absolute path");
|
|
if (rexeced_flag)
|
|
closefrom(REEXEC_MIN_FREE_FD);
|
|
else
|
|
closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
|
|
|
|
#ifdef WITH_OPENSSL
|
|
OpenSSL_add_all_algorithms();
|
|
#endif
|
|
|
|
/* If requested, redirect the logs to the specified logfile. */
|
|
if (logfile != NULL)
|
|
log_redirect_stderr_to(logfile);
|
|
/*
|
|
* Force logging to stderr until we have loaded the private host
|
|
* key (unless started from inetd)
|
|
*/
|
|
log_init(__progname,
|
|
options.log_level == SYSLOG_LEVEL_NOT_SET ?
|
|
SYSLOG_LEVEL_INFO : options.log_level,
|
|
options.log_facility == SYSLOG_FACILITY_NOT_SET ?
|
|
SYSLOG_FACILITY_AUTH : options.log_facility,
|
|
log_stderr || !inetd_flag);
|
|
|
|
/*
|
|
* Unset KRB5CCNAME, otherwise the user's session may inherit it from
|
|
* root's environment
|
|
*/
|
|
if (getenv("KRB5CCNAME") != NULL)
|
|
(void) unsetenv("KRB5CCNAME");
|
|
|
|
sensitive_data.have_ssh2_key = 0;
|
|
|
|
/*
|
|
* If we're not doing an extended test do not silently ignore connection
|
|
* test params.
|
|
*/
|
|
if (test_flag < 2 && connection_info != NULL)
|
|
fatal("Config test connection parameter (-C) provided without "
|
|
"test mode (-T)");
|
|
|
|
/* Fetch our configuration */
|
|
if ((cfg = sshbuf_new()) == NULL)
|
|
fatal("%s: sshbuf_new failed", __func__);
|
|
if (rexeced_flag)
|
|
recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg);
|
|
else if (strcasecmp(config_file_name, "none") != 0)
|
|
load_server_config(config_file_name, cfg);
|
|
|
|
parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
|
|
cfg, NULL);
|
|
|
|
seed_rng();
|
|
|
|
/* Fill in default values for those options not explicitly set. */
|
|
fill_default_server_options(&options);
|
|
|
|
/* challenge-response is implemented via keyboard interactive */
|
|
if (options.challenge_response_authentication)
|
|
options.kbd_interactive_authentication = 1;
|
|
|
|
/* Check that options are sensible */
|
|
if (options.authorized_keys_command_user == NULL &&
|
|
(options.authorized_keys_command != NULL &&
|
|
strcasecmp(options.authorized_keys_command, "none") != 0))
|
|
fatal("AuthorizedKeysCommand set without "
|
|
"AuthorizedKeysCommandUser");
|
|
if (options.authorized_principals_command_user == NULL &&
|
|
(options.authorized_principals_command != NULL &&
|
|
strcasecmp(options.authorized_principals_command, "none") != 0))
|
|
fatal("AuthorizedPrincipalsCommand set without "
|
|
"AuthorizedPrincipalsCommandUser");
|
|
|
|
/*
|
|
* Check whether there is any path through configured auth methods.
|
|
* Unfortunately it is not possible to verify this generally before
|
|
* daemonisation in the presence of Match block, but this catches
|
|
* and warns for trivial misconfigurations that could break login.
|
|
*/
|
|
if (options.num_auth_methods != 0) {
|
|
for (i = 0; i < options.num_auth_methods; i++) {
|
|
if (auth2_methods_valid(options.auth_methods[i],
|
|
1) == 0)
|
|
break;
|
|
}
|
|
if (i >= options.num_auth_methods)
|
|
fatal("AuthenticationMethods cannot be satisfied by "
|
|
"enabled authentication methods");
|
|
}
|
|
|
|
/* Check that there are no remaining arguments. */
|
|
if (optind < ac) {
|
|
fprintf(stderr, "Extra argument %s.\n", av[optind]);
|
|
exit(1);
|
|
}
|
|
|
|
debug("sshd version %s, %s", SSH_VERSION,
|
|
#ifdef WITH_OPENSSL
|
|
SSLeay_version(SSLEAY_VERSION)
|
|
#else
|
|
"without OpenSSL"
|
|
#endif
|
|
);
|
|
|
|
/* Store privilege separation user for later use if required. */
|
|
privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0);
|
|
if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
|
|
if (privsep_chroot || options.kerberos_authentication)
|
|
fatal("Privilege separation user %s does not exist",
|
|
SSH_PRIVSEP_USER);
|
|
} else {
|
|
privsep_pw = pwcopy(privsep_pw);
|
|
freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
|
|
privsep_pw->pw_passwd = xstrdup("*");
|
|
}
|
|
endpwent();
|
|
|
|
/* load host keys */
|
|
sensitive_data.host_keys = xcalloc(options.num_host_key_files,
|
|
sizeof(struct sshkey *));
|
|
sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
|
|
sizeof(struct sshkey *));
|
|
|
|
if (options.host_key_agent) {
|
|
if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
|
|
setenv(SSH_AUTHSOCKET_ENV_NAME,
|
|
options.host_key_agent, 1);
|
|
if ((r = ssh_get_authentication_socket(NULL)) == 0)
|
|
have_agent = 1;
|
|
else
|
|
error("Could not connect to agent \"%s\": %s",
|
|
options.host_key_agent, ssh_err(r));
|
|
}
|
|
|
|
for (i = 0; i < options.num_host_key_files; i++) {
|
|
if (options.host_key_files[i] == NULL)
|
|
continue;
|
|
if ((r = sshkey_load_private(options.host_key_files[i], "",
|
|
&key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
|
|
error("Error loading host key \"%s\": %s",
|
|
options.host_key_files[i], ssh_err(r));
|
|
if ((r = sshkey_load_public(options.host_key_files[i],
|
|
&pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
|
|
error("Error loading host key \"%s\": %s",
|
|
options.host_key_files[i], ssh_err(r));
|
|
if (pubkey == NULL && key != NULL)
|
|
if ((r = sshkey_demote(key, &pubkey)) != 0)
|
|
fatal("Could not demote key: \"%s\": %s",
|
|
options.host_key_files[i], ssh_err(r));
|
|
sensitive_data.host_keys[i] = key;
|
|
sensitive_data.host_pubkeys[i] = pubkey;
|
|
|
|
if (key == NULL && pubkey != NULL && have_agent) {
|
|
debug("will rely on agent for hostkey %s",
|
|
options.host_key_files[i]);
|
|
keytype = pubkey->type;
|
|
} else if (key != NULL) {
|
|
keytype = key->type;
|
|
accumulate_host_timing_secret(cfg, key);
|
|
} else {
|
|
error("Could not load host key: %s",
|
|
options.host_key_files[i]);
|
|
sensitive_data.host_keys[i] = NULL;
|
|
sensitive_data.host_pubkeys[i] = NULL;
|
|
continue;
|
|
}
|
|
|
|
switch (keytype) {
|
|
case KEY_RSA:
|
|
case KEY_DSA:
|
|
case KEY_ECDSA:
|
|
case KEY_ED25519:
|
|
case KEY_XMSS:
|
|
if (have_agent || key != NULL)
|
|
sensitive_data.have_ssh2_key = 1;
|
|
break;
|
|
}
|
|
if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
|
|
SSH_FP_DEFAULT)) == NULL)
|
|
fatal("sshkey_fingerprint failed");
|
|
debug("%s host key #%d: %s %s",
|
|
key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
|
|
free(fp);
|
|
}
|
|
accumulate_host_timing_secret(cfg, NULL);
|
|
if (!sensitive_data.have_ssh2_key) {
|
|
logit("sshd: no hostkeys available -- exiting.");
|
|
exit(1);
|
|
}
|
|
|
|
/*
|
|
* Load certificates. They are stored in an array at identical
|
|
* indices to the public keys that they relate to.
|
|
*/
|
|
sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
|
|
sizeof(struct sshkey *));
|
|
for (i = 0; i < options.num_host_key_files; i++)
|
|
sensitive_data.host_certificates[i] = NULL;
|
|
|
|
for (i = 0; i < options.num_host_cert_files; i++) {
|
|
if (options.host_cert_files[i] == NULL)
|
|
continue;
|
|
if ((r = sshkey_load_public(options.host_cert_files[i],
|
|
&key, NULL)) != 0) {
|
|
error("Could not load host certificate \"%s\": %s",
|
|
options.host_cert_files[i], ssh_err(r));
|
|
continue;
|
|
}
|
|
if (!sshkey_is_cert(key)) {
|
|
error("Certificate file is not a certificate: %s",
|
|
options.host_cert_files[i]);
|
|
sshkey_free(key);
|
|
continue;
|
|
}
|
|
/* Find matching private key */
|
|
for (j = 0; j < options.num_host_key_files; j++) {
|
|
if (sshkey_equal_public(key,
|
|
sensitive_data.host_keys[j])) {
|
|
sensitive_data.host_certificates[j] = key;
|
|
break;
|
|
}
|
|
}
|
|
if (j >= options.num_host_key_files) {
|
|
error("No matching private key for certificate: %s",
|
|
options.host_cert_files[i]);
|
|
sshkey_free(key);
|
|
continue;
|
|
}
|
|
sensitive_data.host_certificates[j] = key;
|
|
debug("host certificate: #%u type %d %s", j, key->type,
|
|
sshkey_type(key));
|
|
}
|
|
|
|
if (privsep_chroot) {
|
|
struct stat st;
|
|
|
|
if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
|
|
(S_ISDIR(st.st_mode) == 0))
|
|
fatal("Missing privilege separation directory: %s",
|
|
_PATH_PRIVSEP_CHROOT_DIR);
|
|
|
|
#ifdef HAVE_CYGWIN
|
|
if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
|
|
(st.st_uid != getuid () ||
|
|
(st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
|
|
#else
|
|
if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
|
|
#endif
|
|
fatal("%s must be owned by root and not group or "
|
|
"world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
|
|
}
|
|
|
|
if (test_flag > 1) {
|
|
/*
|
|
* If no connection info was provided by -C then use
|
|
* use a blank one that will cause no predicate to match.
|
|
*/
|
|
if (connection_info == NULL)
|
|
connection_info = get_connection_info(0, 0);
|
|
parse_server_match_config(&options, connection_info);
|
|
dump_config(&options);
|
|
}
|
|
|
|
/* Configuration looks good, so exit if in test mode. */
|
|
if (test_flag)
|
|
exit(0);
|
|
|
|
/*
|
|
* Clear out any supplemental groups we may have inherited. This
|
|
* prevents inadvertent creation of files with bad modes (in the
|
|
* portable version at least, it's certainly possible for PAM
|
|
* to create a file, and we can't control the code in every
|
|
* module which might be used).
|
|
*/
|
|
if (setgroups(0, NULL) < 0)
|
|
debug("setgroups() failed: %.200s", strerror(errno));
|
|
|
|
if (rexec_flag) {
|
|
if (rexec_argc < 0)
|
|
fatal("rexec_argc %d < 0", rexec_argc);
|
|
rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
|
|
for (i = 0; i < (u_int)rexec_argc; i++) {
|
|
debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
|
|
rexec_argv[i] = saved_argv[i];
|
|
}
|
|
rexec_argv[rexec_argc] = "-R";
|
|
rexec_argv[rexec_argc + 1] = NULL;
|
|
}
|
|
|
|
/* Ensure that umask disallows at least group and world write */
|
|
new_umask = umask(0077) | 0022;
|
|
(void) umask(new_umask);
|
|
|
|
/* Initialize the log (it is reinitialized below in case we forked). */
|
|
if (debug_flag && (!inetd_flag || rexeced_flag))
|
|
log_stderr = 1;
|
|
log_init(__progname, options.log_level, options.log_facility, log_stderr);
|
|
|
|
/*
|
|
* If not in debugging mode, not started from inetd and not already
|
|
* daemonized (eg re-exec via SIGHUP), disconnect from the controlling
|
|
* terminal, and fork. The original process exits.
|
|
*/
|
|
already_daemon = daemonized();
|
|
if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
|
|
|
|
if (daemon(0, 0) < 0)
|
|
fatal("daemon() failed: %.200s", strerror(errno));
|
|
|
|
disconnect_controlling_tty();
|
|
}
|
|
/* Reinitialize the log (because of the fork above). */
|
|
log_init(__progname, options.log_level, options.log_facility, log_stderr);
|
|
|
|
/* Avoid killing the process in high-pressure swapping environments. */
|
|
if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
|
|
debug("madvise(): %.200s", strerror(errno));
|
|
|
|
/* Chdir to the root directory so that the current disk can be
|
|
unmounted if desired. */
|
|
if (chdir("/") == -1)
|
|
error("chdir(\"/\"): %s", strerror(errno));
|
|
|
|
/* ignore SIGPIPE */
|
|
signal(SIGPIPE, SIG_IGN);
|
|
|
|
/* Get a connection, either from inetd or a listening TCP socket */
|
|
if (inetd_flag) {
|
|
server_accept_inetd(&sock_in, &sock_out);
|
|
} else {
|
|
platform_pre_listen();
|
|
server_listen();
|
|
|
|
signal(SIGHUP, sighup_handler);
|
|
signal(SIGCHLD, main_sigchld_handler);
|
|
signal(SIGTERM, sigterm_handler);
|
|
signal(SIGQUIT, sigterm_handler);
|
|
|
|
/*
|
|
* Write out the pid file after the sigterm handler
|
|
* is setup and the listen sockets are bound
|
|
*/
|
|
if (options.pid_file != NULL && !debug_flag) {
|
|
FILE *f = fopen(options.pid_file, "w");
|
|
|
|
if (f == NULL) {
|
|
error("Couldn't create pid file \"%s\": %s",
|
|
options.pid_file, strerror(errno));
|
|
} else {
|
|
fprintf(f, "%ld\n", (long) getpid());
|
|
fclose(f);
|
|
}
|
|
}
|
|
|
|
/* Accept a connection and return in a forked child */
|
|
server_accept_loop(&sock_in, &sock_out,
|
|
&newsock, config_s);
|
|
}
|
|
|
|
/* This is the child processing a new connection. */
|
|
setproctitle("%s", "[accepted]");
|
|
|
|
/*
|
|
* Create a new session and process group since the 4.4BSD
|
|
* setlogin() affects the entire process group. We don't
|
|
* want the child to be able to affect the parent.
|
|
*/
|
|
#if !defined(SSHD_ACQUIRES_CTTY)
|
|
/*
|
|
* If setsid is called, on some platforms sshd will later acquire a
|
|
* controlling terminal which will result in "could not set
|
|
* controlling tty" errors.
|
|
*/
|
|
if (!debug_flag && !inetd_flag && setsid() < 0)
|
|
error("setsid: %.100s", strerror(errno));
|
|
#endif
|
|
|
|
if (rexec_flag) {
|
|
int fd;
|
|
|
|
debug("rexec start in %d out %d newsock %d pipe %d sock %d",
|
|
sock_in, sock_out, newsock, startup_pipe, config_s[0]);
|
|
dup2(newsock, STDIN_FILENO);
|
|
dup2(STDIN_FILENO, STDOUT_FILENO);
|
|
if (startup_pipe == -1)
|
|
close(REEXEC_STARTUP_PIPE_FD);
|
|
else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
|
|
dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
|
|
close(startup_pipe);
|
|
startup_pipe = REEXEC_STARTUP_PIPE_FD;
|
|
}
|
|
|
|
dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
|
|
close(config_s[1]);
|
|
|
|
execv(rexec_argv[0], rexec_argv);
|
|
|
|
/* Reexec has failed, fall back and continue */
|
|
error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
|
|
recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
|
|
log_init(__progname, options.log_level,
|
|
options.log_facility, log_stderr);
|
|
|
|
/* Clean up fds */
|
|
close(REEXEC_CONFIG_PASS_FD);
|
|
newsock = sock_out = sock_in = dup(STDIN_FILENO);
|
|
if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
|
|
dup2(fd, STDIN_FILENO);
|
|
dup2(fd, STDOUT_FILENO);
|
|
if (fd > STDERR_FILENO)
|
|
close(fd);
|
|
}
|
|
debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
|
|
sock_in, sock_out, newsock, startup_pipe, config_s[0]);
|
|
}
|
|
|
|
/* Executed child processes don't need these. */
|
|
fcntl(sock_out, F_SETFD, FD_CLOEXEC);
|
|
fcntl(sock_in, F_SETFD, FD_CLOEXEC);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
#ifdef __FreeBSD__
|
|
/*
|
|
* Initialize the resolver. This may not happen automatically
|
|
* before privsep chroot().
|
|
*/
|
|
if ((_res.options & RES_INIT) == 0) {
|
|
debug("res_init()");
|
|
res_init();
|
|
}
|
|
#ifdef GSSAPI
|
|
/*
|
|
* Force GSS-API to parse its configuration and load any
|
|
* mechanism plugins.
|
|
*/
|
|
{
|
|
gss_OID_set mechs;
|
|
OM_uint32 minor_status;
|
|
gss_indicate_mechs(&minor_status, &mechs);
|
|
gss_release_oid_set(&minor_status, &mechs);
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
/*
|
|
* Register our connection. This turns encryption off because we do
|
|
* not have a key.
|
|
*/
|
|
packet_set_connection(sock_in, sock_out);
|
|
packet_set_server();
|
|
ssh = active_state; /* XXX */
|
|
|
|
check_ip_options(ssh);
|
|
|
|
/* Prepare the channels layer */
|
|
channel_init_channels(ssh);
|
|
channel_set_af(ssh, options.address_family);
|
|
process_permitopen(ssh, &options);
|
|
|
|
/* Set SO_KEEPALIVE if requested. */
|
|
if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
|
|
setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
|
|
error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
|
|
|
|
if ((remote_port = ssh_remote_port(ssh)) < 0) {
|
|
debug("ssh_remote_port failed");
|
|
cleanup_exit(255);
|
|
}
|
|
|
|
if (options.routing_domain != NULL)
|
|
set_process_rdomain(ssh, options.routing_domain);
|
|
|
|
/*
|
|
* The rest of the code depends on the fact that
|
|
* ssh_remote_ipaddr() caches the remote ip, even if
|
|
* the socket goes away.
|
|
*/
|
|
remote_ip = ssh_remote_ipaddr(ssh);
|
|
|
|
#ifdef SSH_AUDIT_EVENTS
|
|
audit_connection_from(remote_ip, remote_port);
|
|
#endif
|
|
#ifdef LIBWRAP
|
|
allow_severity = options.log_facility|LOG_INFO;
|
|
deny_severity = options.log_facility|LOG_WARNING;
|
|
/* Check whether logins are denied from this host. */
|
|
if (packet_connection_is_on_socket()) {
|
|
struct request_info req;
|
|
|
|
request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
|
|
fromhost(&req);
|
|
|
|
if (!hosts_access(&req)) {
|
|
debug("Connection refused by tcp wrapper");
|
|
refuse(&req);
|
|
/* NOTREACHED */
|
|
fatal("libwrap refuse returns");
|
|
}
|
|
}
|
|
#endif /* LIBWRAP */
|
|
|
|
rdomain = ssh_packet_rdomain_in(ssh);
|
|
|
|
/* Log the connection. */
|
|
laddr = get_local_ipaddr(sock_in);
|
|
verbose("Connection from %s port %d on %s port %d%s%s%s",
|
|
remote_ip, remote_port, laddr, ssh_local_port(ssh),
|
|
rdomain == NULL ? "" : " rdomain \"",
|
|
rdomain == NULL ? "" : rdomain,
|
|
rdomain == NULL ? "" : "\"");
|
|
free(laddr);
|
|
|
|
/*
|
|
* 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(ssh, sock_in, sock_out);
|
|
packet_set_nonblocking();
|
|
|
|
/* allocate authentication context */
|
|
authctxt = xcalloc(1, sizeof(*authctxt));
|
|
|
|
authctxt->loginmsg = loginmsg;
|
|
|
|
/* XXX global for cleanup, access from other modules */
|
|
the_authctxt = authctxt;
|
|
|
|
/* Set default key authentication options */
|
|
if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
|
|
fatal("allocation failed");
|
|
|
|
/* prepare buffer to collect messages to display to user after login */
|
|
if ((loginmsg = sshbuf_new()) == NULL)
|
|
fatal("%s: sshbuf_new failed", __func__);
|
|
auth_debug_reset();
|
|
|
|
BLACKLIST_INIT();
|
|
|
|
if (use_privsep) {
|
|
if (privsep_preauth(authctxt) == 1)
|
|
goto authenticated;
|
|
} else if (have_agent) {
|
|
if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
|
|
error("Unable to get agent socket: %s", ssh_err(r));
|
|
have_agent = 0;
|
|
}
|
|
}
|
|
|
|
/* perform the key exchange */
|
|
/* authenticate user and start session */
|
|
do_ssh2_kex();
|
|
do_authentication2(authctxt);
|
|
|
|
/*
|
|
* If we use privilege separation, the unprivileged child transfers
|
|
* the current keystate and exits
|
|
*/
|
|
if (use_privsep) {
|
|
mm_send_keystate(pmonitor);
|
|
packet_clear_keys();
|
|
exit(0);
|
|
}
|
|
|
|
authenticated:
|
|
/*
|
|
* Cancel the alarm we set to limit the time taken for
|
|
* authentication.
|
|
*/
|
|
alarm(0);
|
|
signal(SIGALRM, SIG_DFL);
|
|
authctxt->authenticated = 1;
|
|
if (startup_pipe != -1) {
|
|
close(startup_pipe);
|
|
startup_pipe = -1;
|
|
}
|
|
|
|
#ifdef SSH_AUDIT_EVENTS
|
|
audit_event(SSH_AUTH_SUCCESS);
|
|
#endif
|
|
|
|
#ifdef GSSAPI
|
|
if (options.gss_authentication) {
|
|
temporarily_use_uid(authctxt->pw);
|
|
ssh_gssapi_storecreds();
|
|
restore_uid();
|
|
}
|
|
#endif
|
|
#ifdef USE_PAM
|
|
if (options.use_pam) {
|
|
do_pam_setcred(1);
|
|
do_pam_session(ssh);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* In privilege separation, we fork another child and prepare
|
|
* file descriptor passing.
|
|
*/
|
|
if (use_privsep) {
|
|
privsep_postauth(authctxt);
|
|
/* the monitor process [priv] will not return */
|
|
}
|
|
|
|
packet_set_timeout(options.client_alive_interval,
|
|
options.client_alive_count_max);
|
|
|
|
/* Try to send all our hostkeys to the client */
|
|
notify_hostkeys(ssh);
|
|
|
|
/* Start session. */
|
|
do_authenticated(ssh, authctxt);
|
|
|
|
/* The connection has been terminated. */
|
|
packet_get_bytes(&ibytes, &obytes);
|
|
verbose("Transferred: sent %llu, received %llu bytes",
|
|
(unsigned long long)obytes, (unsigned long long)ibytes);
|
|
|
|
verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
|
|
|
|
#ifdef USE_PAM
|
|
if (options.use_pam)
|
|
finish_pam();
|
|
#endif /* USE_PAM */
|
|
|
|
#ifdef SSH_AUDIT_EVENTS
|
|
PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
|
|
#endif
|
|
|
|
packet_close();
|
|
|
|
if (use_privsep)
|
|
mm_terminate();
|
|
|
|
exit(0);
|
|
}
|
|
|
|
int
|
|
sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey,
|
|
u_char **signature, size_t *slenp, const u_char *data, size_t dlen,
|
|
const char *alg, u_int flag)
|
|
{
|
|
int r;
|
|
|
|
if (privkey) {
|
|
if (PRIVSEP(sshkey_sign(privkey, signature, slenp, data, dlen,
|
|
alg, datafellows)) < 0)
|
|
fatal("%s: key_sign failed", __func__);
|
|
} else if (use_privsep) {
|
|
if (mm_sshkey_sign(pubkey, signature, slenp, data, dlen,
|
|
alg, datafellows) < 0)
|
|
fatal("%s: pubkey_sign failed", __func__);
|
|
} else {
|
|
if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slenp,
|
|
data, dlen, alg, datafellows)) != 0)
|
|
fatal("%s: ssh_agent_sign failed: %s",
|
|
__func__, ssh_err(r));
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* SSH2 key exchange */
|
|
static void
|
|
do_ssh2_kex(void)
|
|
{
|
|
char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
|
|
struct kex *kex;
|
|
int r;
|
|
|
|
myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
|
|
options.kex_algorithms);
|
|
myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
|
|
options.ciphers);
|
|
myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
|
|
options.ciphers);
|
|
myproposal[PROPOSAL_MAC_ALGS_CTOS] =
|
|
myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
|
|
|
|
if (options.compression == COMP_NONE) {
|
|
myproposal[PROPOSAL_COMP_ALGS_CTOS] =
|
|
myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
|
|
}
|
|
|
|
if (options.rekey_limit || options.rekey_interval)
|
|
packet_set_rekey_limits(options.rekey_limit,
|
|
options.rekey_interval);
|
|
|
|
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
|
|
list_hostkey_types());
|
|
|
|
/* start key exchange */
|
|
if ((r = kex_setup(active_state, myproposal)) != 0)
|
|
fatal("kex_setup: %s", ssh_err(r));
|
|
kex = active_state->kex;
|
|
#ifdef WITH_OPENSSL
|
|
kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
|
|
kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
|
|
kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
|
|
kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
|
|
kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
|
|
kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
|
|
kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
|
|
# ifdef OPENSSL_HAS_ECC
|
|
kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
|
|
# endif
|
|
#endif
|
|
kex->kex[KEX_C25519_SHA256] = kexc25519_server;
|
|
kex->server = 1;
|
|
kex->client_version_string=client_version_string;
|
|
kex->server_version_string=server_version_string;
|
|
kex->load_host_public_key=&get_hostkey_public_by_type;
|
|
kex->load_host_private_key=&get_hostkey_private_by_type;
|
|
kex->host_key_index=&get_hostkey_index;
|
|
kex->sign = sshd_hostkey_sign;
|
|
|
|
ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
|
|
|
|
session_id2 = kex->session_id;
|
|
session_id2_len = kex->session_id_len;
|
|
|
|
#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("KEX done");
|
|
}
|
|
|
|
/* server specific fatal cleanup */
|
|
void
|
|
cleanup_exit(int i)
|
|
{
|
|
struct ssh *ssh = active_state; /* XXX */
|
|
|
|
if (the_authctxt) {
|
|
do_cleanup(ssh, the_authctxt);
|
|
if (use_privsep && privsep_is_preauth &&
|
|
pmonitor != NULL && pmonitor->m_pid > 1) {
|
|
debug("Killing privsep child %d", pmonitor->m_pid);
|
|
if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
|
|
errno != ESRCH)
|
|
error("%s: kill(%d): %s", __func__,
|
|
pmonitor->m_pid, strerror(errno));
|
|
}
|
|
}
|
|
#ifdef SSH_AUDIT_EVENTS
|
|
/* done after do_cleanup so it can cancel the PAM auth 'thread' */
|
|
if (!use_privsep || mm_is_monitor())
|
|
audit_event(SSH_CONNECTION_ABANDON);
|
|
#endif
|
|
_exit(i);
|
|
}
|