upstream commit
Add a ProxyJump ssh_config(5) option and corresponding -J
ssh(1) command-line flag to allow simplified indirection through a SSH
bastion or "jump host".
These options construct a proxy command that connects to the
specified jump host(s) (more than one may be specified) and uses
port-forwarding to establish a connection to the next destination.
This codifies the safest way of indirecting connections through SSH
servers and makes it easy to use.
ok markus@
Upstream-ID: fa899cb8b26d889da8f142eb9774c1ea36b04397
diff --git a/ssh.c b/ssh.c
index e7d4fd9..a9b6853 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.442 2016/06/03 04:09:39 dtucker Exp $ */
+/* $OpenBSD: ssh.c,v 1.443 2016/07/15 00:24:30 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -330,7 +330,7 @@
* NB. this function must operate with a options having undefined members.
*/
static int
-check_follow_cname(char **namep, const char *cname)
+check_follow_cname(int direct, char **namep, const char *cname)
{
int i;
struct allowed_cname *rule;
@@ -342,9 +342,9 @@
return 0;
/*
* Don't attempt to canonicalize names that will be interpreted by
- * a proxy unless the user specifically requests so.
+ * a proxy or jump host unless the user specifically requests so.
*/
- if (!option_clear_or_none(options.proxy_command) &&
+ if (!direct &&
options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
return 0;
debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
@@ -371,7 +371,7 @@
static struct addrinfo *
resolve_canonicalize(char **hostp, int port)
{
- int i, ndots;
+ int i, direct, ndots;
char *cp, *fullhost, newname[NI_MAXHOST];
struct addrinfo *addrs;
@@ -382,7 +382,9 @@
* Don't attempt to canonicalize names that will be interpreted by
* a proxy unless the user specifically requests so.
*/
- if (!option_clear_or_none(options.proxy_command) &&
+ direct = option_clear_or_none(options.proxy_command) &&
+ options.jump_host == NULL;
+ if (!direct &&
options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
return NULL;
@@ -437,7 +439,7 @@
/* Remove trailing '.' */
fullhost[strlen(fullhost) - 1] = '\0';
/* Follow CNAME if requested */
- if (!check_follow_cname(&fullhost, newname)) {
+ if (!check_follow_cname(direct, &fullhost, newname)) {
debug("Canonicalized hostname \"%s\" => \"%s\"",
*hostp, fullhost);
}
@@ -510,7 +512,7 @@
main(int ac, char **av)
{
struct ssh *ssh = NULL;
- int i, r, opt, exit_status, use_syslog, config_test = 0;
+ int i, r, opt, exit_status, use_syslog, direct, config_test = 0;
char *p, *cp, *line, *argv0, buf[PATH_MAX], *host_arg, *logfile;
char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
char cname[NI_MAXHOST], uidstr[32], *conn_hash_hex;
@@ -603,7 +605,7 @@
again:
while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
- "ACD:E:F:GI:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
+ "ACD:E:F:GI:J:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
switch (opt) {
case '1':
options.protocol = SSH_PROTO_1;
@@ -728,6 +730,15 @@
fprintf(stderr, "no support for PKCS#11.\n");
#endif
break;
+ case 'J':
+ if (options.jump_host != NULL)
+ fatal("Only a single -J option permitted");
+ if (options.proxy_command != NULL)
+ fatal("Cannot specify -J with ProxyCommand");
+ if (parse_jump(optarg, &options, 1) == -1)
+ fatal("Invalid -J argument");
+ options.proxy_command = xstrdup("none");
+ break;
case 't':
if (options.request_tty == REQUEST_TTY_YES)
options.request_tty = REQUEST_TTY_FORCE;
@@ -739,8 +750,10 @@
debug_flag = 1;
options.log_level = SYSLOG_LEVEL_DEBUG1;
} else {
- if (options.log_level < SYSLOG_LEVEL_DEBUG3)
+ if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
+ debug_flag++;
options.log_level++;
+ }
}
break;
case 'V':
@@ -1038,9 +1051,10 @@
* has specifically requested canonicalisation for this case via
* CanonicalizeHostname=always
*/
- if (addrs == NULL && options.num_permitted_cnames != 0 &&
- (option_clear_or_none(options.proxy_command) ||
- options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
+ direct = option_clear_or_none(options.proxy_command) &&
+ options.jump_host == NULL;
+ if (addrs == NULL && options.num_permitted_cnames != 0 && (direct ||
+ options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
if ((addrs = resolve_host(host, options.port,
option_clear_or_none(options.proxy_command),
cname, sizeof(cname))) == NULL) {
@@ -1048,7 +1062,7 @@
if (option_clear_or_none(options.proxy_command))
cleanup_exit(255); /* logged in resolve_host */
} else
- check_follow_cname(&host, cname);
+ check_follow_cname(direct, &host, cname);
}
/*
@@ -1073,6 +1087,41 @@
/* Fill configuration defaults. */
fill_default_options(&options);
+ /*
+ * If ProxyJump option specified, then construct a ProxyCommand now.
+ */
+ if (options.jump_host != NULL) {
+ char port_s[8];
+
+ /* Consistency check */
+ if (options.proxy_command != NULL)
+ fatal("inconsistent options: ProxyCommand+ProxyJump");
+ /* Never use FD passing for ProxyJump */
+ options.proxy_use_fdpass = 0;
+ snprintf(port_s, sizeof(port_s), "%d", options.jump_port);
+ xasprintf(&options.proxy_command,
+ "ssh%s%s%s%s%s%s%s%s%s%.*s -W %%h:%%p %s",
+ /* Optional "-l user" argument if jump_user set */
+ options.jump_user == NULL ? "" : " -l ",
+ options.jump_user == NULL ? "" : options.jump_user,
+ /* Optional "-p port" argument if jump_port set */
+ options.jump_port <= 0 ? "" : " -p ",
+ options.jump_port <= 0 ? "" : port_s,
+ /* Optional additional jump hosts ",..." */
+ options.jump_extra == NULL ? "" : " -J ",
+ options.jump_extra == NULL ? "" : options.jump_extra,
+ /* Optional "-F" argumment if -F specified */
+ config == NULL ? "" : " -F ",
+ config == NULL ? "" : config,
+ /* Optional "-v" arguments if -v set */
+ debug_flag ? " -" : "",
+ debug_flag, "vvv",
+ /* Mandatory hostname */
+ options.jump_host);
+ debug("Setting implicit ProxyCommand from ProxyJump: %s",
+ options.proxy_command);
+ }
+
if (options.port == 0)
options.port = default_ssh_port();
channel_set_af(options.address_family);