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authorJan Cholasta <jcholast@redhat.com>2012-02-03 22:56:13 +0100
committerJakub Hrozek <jhrozek@redhat.com>2012-02-07 00:26:58 +0100
commit9a3e40dc49c1e38bf58e45be5adff37615f3910b (patch)
tree604797303c0fd8baa7e7a66c35427344f566344c /src
parent558998ce664055a75595371118f818084d8f2b23 (diff)
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SSH: OpenSSH known_hosts client
Diffstat (limited to 'src')
-rw-r--r--src/man/Makefile.am2
-rw-r--r--src/man/sss_ssh_knownhostsproxy.1.xml120
-rw-r--r--src/sss_client/ssh/sss_ssh_knownhostsproxy.c401
3 files changed, 522 insertions, 1 deletions
diff --git a/src/man/Makefile.am b/src/man/Makefile.am
index f6307715e..c0c2281e7 100644
--- a/src/man/Makefile.am
+++ b/src/man/Makefile.am
@@ -39,7 +39,7 @@ man_MANS = \
sssd-krb5.5 sssd-ipa.5 sssd-simple.5 \
sssd_krb5_locator_plugin.8 sss_groupshow.8 \
pam_sss.8 sss_obfuscate.8 sss_cache.8 sss_debuglevel.8 \
- sss_ssh_authorizedkeys.1
+ sss_ssh_authorizedkeys.1 sss_ssh_knownhostsproxy.1
EXTRA_DIST = $(man_MANS:%=%.xml) $(wildcard $(srcdir)/include/*.xml)
SUFFIXES = .1.xml .1 .3.xml .3 .5.xml .5 .8.xml .8
diff --git a/src/man/sss_ssh_knownhostsproxy.1.xml b/src/man/sss_ssh_knownhostsproxy.1.xml
new file mode 100644
index 000000000..1cb16049b
--- /dev/null
+++ b/src/man/sss_ssh_knownhostsproxy.1.xml
@@ -0,0 +1,120 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE reference PUBLIC "-//OASIS//DTD DocBook V4.4//EN"
+"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
+<reference>
+<title>SSSD Manual pages</title>
+<refentry>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/upstream.xml" />
+
+ <refmeta>
+ <refentrytitle>sss_ssh_knownhostsproxy</refentrytitle>
+ <manvolnum>1</manvolnum>
+ </refmeta>
+
+ <refnamediv id='name'>
+ <refname>sss_ssh_knownhostsproxy</refname>
+ <refpurpose>get OpenSSH host keys</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv id='synopsis'>
+ <cmdsynopsis>
+ <command>sss_ssh_knownhostsproxy</command>
+ <arg choice='opt'>
+ <replaceable>options</replaceable>
+ </arg>
+ <arg choice='plain'><replaceable>HOST</replaceable></arg>
+ <arg choice='opt'><replaceable>PROXY_COMMAND</replaceable></arg>
+ </cmdsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1 id='description'>
+ <title>DESCRIPTION</title>
+ <para>
+ <command>sss_ssh_knownhostsproxy</command> acquires SSH host
+ public keys for host <replaceable>HOST</replaceable>, stores
+ them in a custom OpenSSH known_hosts file (see the
+ <quote>SSH_KNOWN_HOSTS FILE FORMAT</quote> section of
+ <citerefentry><refentrytitle>sshd</refentrytitle>
+ <manvolnum>8</manvolnum></citerefentry> for more
+ information) and estabilishes connection to the host.
+ </para>
+ <para>
+ If <replaceable>PROXY_COMMAND</replaceable> is specified,
+ it is used to create the connection to the host instead of
+ opening a socket.
+ </para>
+ <para>
+ <citerefentry><refentrytitle>ssh</refentrytitle>
+ <manvolnum>1</manvolnum></citerefentry> can be configured to
+ use <command>sss_ssh_knownhostsproxy</command> for host key
+ authentication by using the following directives for
+ <citerefentry><refentrytitle>ssh</refentrytitle>
+ <manvolnum>1</manvolnum></citerefentry> configuration:
+<programlisting>
+ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h
+UserKnownHostsFile2 .ssh/sss_known_hosts
+</programlisting>
+ </para>
+ <para>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/experimental.xml" />
+ </para>
+ </refsect1>
+
+ <refsect1 id='options'>
+ <title>OPTIONS</title>
+ <variablelist remap='IP'>
+ <varlistentry>
+ <term>
+ <option>-f</option>,<option>--file</option>
+ <replaceable>FILE</replaceable>
+ </term>
+ <listitem>
+ <para>
+ Store host public keys in file <replaceable>FILE</replaceable>.
+ By default, <filename>.ssh/sss_known_hosts</filename> is used.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>
+ <option>-p</option>,<option>--port</option>
+ <replaceable>PORT</replaceable>
+ </term>
+ <listitem>
+ <para>
+ Use port <replaceable>PORT</replaceable> to connect to the host.
+ By default, port 22 is used.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>
+ <option>-d</option>,<option>--domain</option>
+ <replaceable>DOMAIN</replaceable>
+ </term>
+ <listitem>
+ <para>
+ Search for host public keys in SSSD domain <replaceable>DOMAIN</replaceable>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/param_help.xml" />
+ </variablelist>
+ </refsect1>
+
+ <refsect1 id='see_also'>
+ <title>SEE ALSO</title>
+ <para>
+ <citerefentry>
+ <refentrytitle>ssh</refentrytitle><manvolnum>8</manvolnum>
+ </citerefentry>,
+ <citerefentry>
+ <refentrytitle>ssh_config</refentrytitle><manvolnum>5</manvolnum>
+ </citerefentry>,
+ <citerefentry>
+ <refentrytitle>sss_ssh_authorizedkeys</refentrytitle><manvolnum>1</manvolnum>
+ </citerefentry>.
+ </para>
+ </refsect1>
+</refentry>
+</reference>
diff --git a/src/sss_client/ssh/sss_ssh_knownhostsproxy.c b/src/sss_client/ssh/sss_ssh_knownhostsproxy.c
new file mode 100644
index 000000000..b95dbe8ef
--- /dev/null
+++ b/src/sss_client/ssh/sss_ssh_knownhostsproxy.c
@@ -0,0 +1,401 @@
+/*
+ Authors:
+ Jan Cholasta <jcholast@redhat.com>
+
+ Copyright (C) 2012 Red Hat
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdio.h>
+#include <talloc.h>
+#include <unistd.h>
+#include <pwd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/select.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <netdb.h>
+#include <popt.h>
+
+#include "util/util.h"
+#include "util/crypto/sss_crypto.h"
+#include "tools/tools_util.h"
+#include "sss_client/sss_cli.h"
+#include "sss_client/ssh/sss_ssh.h"
+
+#define DEFAULT_FILE ".ssh/sss_known_hosts"
+
+#define BUFFER_SIZE 8192
+
+/* run proxy command */
+static int run_proxy(char **args)
+{
+ int ret;
+
+ execv(args[0], (char * const *)args);
+
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("execv() failed (%d): %s\n",
+ ret, strerror(ret)));
+ ERROR("Failed to execute proxy command\n");
+
+ return EXIT_FAILURE;
+}
+
+/* connect to server */
+static int run_connect(int af, struct sockaddr *addr, size_t addr_len)
+{
+ int flags;
+ int sock;
+ fd_set fds;
+ char buffer[BUFFER_SIZE];
+ ssize_t rd_len, wr_len, wr_offs;
+ int ret;
+
+ /* set O_NONBLOCK on standard input */
+ flags = fcntl(0, F_GETFL);
+ if (flags == -1) {
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("fcntl() failed (%d): %s\n",
+ ret, strerror(ret)));
+ return EXIT_FAILURE;
+ }
+
+ ret = fcntl(0, F_SETFL, flags | O_NONBLOCK);
+ if (ret == -1) {
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("fcntl() failed (%d): %s\n",
+ ret, strerror(ret)));
+ return EXIT_FAILURE;
+ }
+
+ /* create socket */
+ sock = socket(af, SOCK_STREAM, IPPROTO_TCP);
+ if (sock == -1) {
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("socket() failed (%d): %s\n",
+ ret, strerror(ret)));
+ ERROR("Failed to open a socket\n");
+ return EXIT_FAILURE;
+ }
+
+ /* connect to the server */
+ ret = connect(sock, addr, addr_len);
+ if (ret == -1) {
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("connect() failed (%d): %s\n",
+ ret, strerror(ret)));
+ ERROR("Failed to connect to the server\n");
+ close(sock);
+ return EXIT_FAILURE;
+ }
+
+ /* set O_NONBLOCK on the socket */
+ flags = fcntl(sock, F_GETFL);
+ if (flags == -1) {
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("fcntl() failed (%d): %s\n",
+ ret, strerror(ret)));
+ close(sock);
+ return EXIT_FAILURE;
+ }
+
+ ret = fcntl(sock, F_SETFL, flags | O_NONBLOCK);
+ if (ret == -1) {
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("fcntl() failed (%d): %s\n",
+ ret, strerror(ret)));
+ close(sock);
+ return EXIT_FAILURE;
+ }
+
+ while (1) {
+ FD_SET(0, &fds);
+ FD_SET(sock, &fds);
+
+ ret = select(sock+1, &fds, NULL, NULL, NULL);
+ if (ret == -1) {
+ if (errno == EINTR || errno == EAGAIN) {
+ continue;
+ }
+
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("select() failed (%d): %s\n",
+ ret, strerror(ret)));
+ close(sock);
+ return EXIT_FAILURE;
+ }
+
+ /* read from standard input & write to socket */
+ if (FD_ISSET(0, &fds)) {
+ rd_len = read(0, buffer, BUFFER_SIZE);
+ if (rd_len == -1) {
+ if (errno == EAGAIN) {
+ continue;
+ }
+
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("read() failed (%d): %s\n",
+ ret, strerror(ret)));
+ close(sock);
+ return EXIT_FAILURE;
+ }
+
+ wr_offs = 0;
+ do {
+ wr_len = send(sock, buffer+wr_offs, rd_len-wr_offs, 0);
+ if (wr_len == -1) {
+ if (errno == EAGAIN) {
+ continue;
+ }
+
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("send() failed (%d): %s\n",
+ ret, strerror(ret)));
+ close(sock);
+ return EXIT_FAILURE;
+ }
+
+ if (wr_len == 0) {
+ close(sock);
+ return EXIT_SUCCESS;
+ }
+
+ wr_offs += wr_len;
+ } while(wr_offs < rd_len);
+ }
+
+ /* read from socket & write to standard output */
+ if (FD_ISSET(sock, &fds)) {
+ rd_len = recv(sock, buffer, BUFFER_SIZE, 0);
+ if (rd_len == -1) {
+ if (errno == EAGAIN) {
+ continue;
+ }
+
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("recv() failed (%d): %s\n",
+ ret, strerror(ret)));
+ close(sock);
+ return EXIT_FAILURE;
+ }
+
+ if (rd_len == 0) {
+ close(sock);
+ return EXIT_SUCCESS;
+ }
+
+ wr_offs = 0;
+ do {
+ wr_len = write(1, buffer+wr_offs, rd_len-wr_offs);
+ if (wr_len == -1) {
+ if (errno == EAGAIN) {
+ continue;
+ }
+
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("write() failed (%d): %s\n",
+ ret, strerror(ret)));
+ close(sock);
+ return EXIT_FAILURE;
+ }
+
+ wr_offs += wr_len;
+ } while(wr_offs < rd_len);
+ }
+ }
+}
+
+int main(int argc, const char **argv)
+{
+ TALLOC_CTX *mem_ctx;
+ int pc_debug = SSSDBG_DEFAULT;
+ const char *pc_file = DEFAULT_FILE;
+ const char *pc_port = "22";
+ const char *pc_domain = NULL;
+ const char *pc_host = NULL;
+ const char **pc_args = NULL;
+ struct poptOption long_options[] = {
+ POPT_AUTOHELP
+ { "debug", '\0', POPT_ARG_INT | POPT_ARGFLAG_DOC_HIDDEN, &pc_debug, 0,
+ _("The debug level to run with"), NULL },
+ { "file", 'f', POPT_ARG_STRING, &pc_file, 0,
+ _("The known_hosts file to use"), NULL },
+ { "port", 'p', POPT_ARG_STRING, &pc_port, 0,
+ _("The port to use to connect to the host"), NULL },
+ { "domain", 'd', POPT_ARG_STRING, &pc_domain, 0,
+ _("The SSSD domain to use"), NULL },
+ POPT_TABLEEND
+ };
+ poptContext pc = NULL;
+ const char *file;
+ struct passwd *pwd;
+ const char *host;
+ FILE *f;
+ struct addrinfo ai_hint, *ai = NULL;
+ struct sss_ssh_pubkey *pubkeys;
+ size_t num_pubkeys, i;
+ char *repr;
+ int ret;
+
+ debug_prg_name = argv[0];
+
+ ret = set_locale();
+ if (ret != EOK) {
+ DEBUG(SSSDBG_CRIT_FAILURE,
+ ("set_locale() failed (%d): %s\n", ret, strerror(ret)));
+ ERROR("Error setting the locale\n");
+ ret = EXIT_FAILURE;
+ goto fini;
+ }
+
+ mem_ctx = talloc_new(NULL);
+ if (!mem_ctx) {
+ ERROR("Not enough memory\n");
+ ret = EXIT_FAILURE;
+ goto fini;
+ }
+
+ /* parse parameters */
+ pc = poptGetContext(NULL, argc, argv, long_options, 0);
+ poptSetOtherOptionHelp(pc, "HOST [PROXY_COMMAND]");
+ while ((ret = poptGetNextOpt(pc)) > 0)
+ ;
+
+ debug_level = debug_convert_old_level(pc_debug);
+
+ if (ret != -1) {
+ BAD_POPT_PARAMS(pc, poptStrerror(ret), ret, fini);
+ }
+
+ pc_host = poptGetArg(pc);
+ if (pc_host == NULL) {
+ BAD_POPT_PARAMS(pc, _("Host not specified\n"), ret, fini);
+ }
+
+ pc_args = poptGetArgs(pc);
+ if (pc_args && pc_args[0] && pc_args[0][0] != '/') {
+ BAD_POPT_PARAMS(pc,
+ _("The path to the proxy command must be absolute\n"),
+ ret, fini);
+ }
+
+ /* get absolute filename of the known_hosts file */
+ if (pc_file && pc_file[0] != '/') {
+ pwd = getpwuid(getuid());
+ if (!pwd) {
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("getpwuid() failed (%d): %s\n",
+ ret, strerror(ret)));
+ ERROR("Failed to get user's home directory\n");
+ ret = EXIT_FAILURE;
+ goto fini;
+ }
+
+ file = talloc_asprintf(mem_ctx, "%s/%s", pwd->pw_dir, pc_file);
+ if (!file) {
+ ERROR("Not enough memory\n");
+ ret = EXIT_FAILURE;
+ goto fini;
+ }
+ } else {
+ file = pc_file;
+ }
+
+ /* get canonic hostname and IP addresses of the host */
+ memset(&ai_hint, 0, sizeof(struct addrinfo));
+ ai_hint.ai_family = AF_UNSPEC;
+ ai_hint.ai_socktype = SOCK_STREAM;
+ ai_hint.ai_protocol = IPPROTO_TCP;
+ ai_hint.ai_flags = AI_CANONNAME | AI_ADDRCONFIG | AI_NUMERICSERV;
+
+ ret = getaddrinfo(pc_host, pc_port, &ai_hint, &ai);
+ if (ret) {
+ DEBUG(SSSDBG_CRIT_FAILURE,
+ ("getaddrinfo() failed (%d): %s\n", ret, gai_strerror(ret)));
+ ERROR("Error looking up host\n");
+ ret = EXIT_FAILURE;
+ goto fini;
+ }
+
+ /* append domain to hostname if domain is specified */
+ if (pc_domain) {
+ host = talloc_asprintf(mem_ctx, "%s@%s", ai[0].ai_canonname, pc_domain);
+ if (!host) {
+ ERROR("Not enough memory\n");
+ ret = EXIT_FAILURE;
+ goto fini;
+ }
+ } else {
+ host = ai[0].ai_canonname;
+ }
+
+ /* look up public keys */
+ ret = sss_ssh_get_pubkeys(mem_ctx, SSS_SSH_GET_HOST_PUBKEYS, host,
+ &pubkeys, &num_pubkeys);
+ if (ret != EOK) {
+ DEBUG(SSSDBG_CRIT_FAILURE,
+ ("sss_ssh_get_pubkeys failed() (%d): %s\n", ret, strerror(ret)));
+ ERROR("Error looking up public keys\n");
+ ret = EXIT_FAILURE;
+ goto fini;
+ }
+
+ /* write known_hosts file */
+ /* FIXME: Do not overwrite the file, handle concurrent access */
+ f = fopen(file, "w");
+ if (!f) {
+ ret = errno;
+ DEBUG(SSSDBG_OP_FAILURE, ("fopen() failed (%d): %s\n",
+ ret, strerror(ret)));
+ ERROR("Can't open known hosts file\n");
+ ret = EXIT_FAILURE;
+ goto fini;
+ }
+
+ fprintf(f,
+ "# Generated by sss_ssh_knownhostsproxy. Please do not modify.\n");
+
+ for (i = 0; i < num_pubkeys; i++) {
+ ret = sss_ssh_format_pubkey(mem_ctx, &pubkeys[i],
+ SSS_SSH_FORMAT_OPENSSH, &repr);
+ if (ret != EOK) {
+ DEBUG(SSSDBG_OP_FAILURE,
+ ("sss_ssh_format_pubkey() failed (%d): %s\n",
+ ret, strerror(ret)));
+ continue;
+ }
+
+ fprintf(f, "%s %s\n", pc_host, repr);
+ }
+
+ fclose(f);
+
+ /* connect to server */
+ if (pc_args) {
+ ret = run_proxy(discard_const(pc_args));
+ } else {
+ ret = run_connect(ai->ai_family, ai->ai_addr, ai->ai_addrlen);
+ }
+
+fini:
+ poptFreeContext(pc);
+ talloc_free(mem_ctx);
+ if (ai) freeaddrinfo(ai);
+
+ return ret;
+}