diff --git a/ChangeLog b/ChangeLog index a3ac3d537..6b0afa720 100644 --- a/ChangeLog +++ b/ChangeLog @@ -50,6 +50,14 @@ [scp.1 ssh.1] some Bx/Ox conversion; From: Jan Stary + - djm@cvs.openbsd.org 2013/08/20 00:11:38 + [readconf.c readconf.h ssh_config.5 sshconnect.c] + Add a ssh_config ProxyUseFDPass option that supports the use of + ProxyCommands that establish a connection and then pass a connected + file descriptor back to ssh(1). This allows the ProxyCommand to exit + rather than have to shuffle data back and forth and enables ssh to use + getpeername, etc. to obtain address information just like it does with + regular directly-connected sockets. ok markus@ 20130808 - (dtucker) [regress/Makefile regress/test-exec.sh] Don't try to use test -nt diff --git a/readconf.c b/readconf.c index 1464430a4..7450081cd 100644 --- a/readconf.c +++ b/readconf.c @@ -1,4 +1,4 @@ -/* $OpenBSD: readconf.c,v 1.204 2013/06/10 19:19:44 dtucker Exp $ */ +/* $OpenBSD: readconf.c,v 1.205 2013/08/20 00:11:37 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -137,7 +137,7 @@ typedef enum { oHashKnownHosts, oTunnel, oTunnelDevice, oLocalCommand, oPermitLocalCommand, oVisualHostKey, oUseRoaming, oZeroKnowledgePasswordAuthentication, - oKexAlgorithms, oIPQoS, oRequestTTY, oIgnoreUnknown, + oKexAlgorithms, oIPQoS, oRequestTTY, oIgnoreUnknown, oProxyUseFdpass, oIgnoredUnknownOption, oDeprecated, oUnsupported } OpCodes; @@ -249,6 +249,7 @@ static struct { { "kexalgorithms", oKexAlgorithms }, { "ipqos", oIPQoS }, { "requesttty", oRequestTTY }, + { "proxyusefdpass", oProxyUseFdpass }, { "ignoreunknown", oIgnoreUnknown }, { NULL, oBadOption } @@ -1072,6 +1073,10 @@ parse_int: charptr = &options->ignored_unknown; goto parse_string; + case oProxyUseFdpass: + intptr = &options->proxy_use_fdpass; + goto parse_flag; + case oDeprecated: debug("%s line %d: Deprecated option \"%s\"", filename, linenum, keyword); @@ -1233,6 +1238,7 @@ initialize_options(Options * options) options->ip_qos_interactive = -1; options->ip_qos_bulk = -1; options->request_tty = -1; + options->proxy_use_fdpass = -1; options->ignored_unknown = NULL; } @@ -1385,6 +1391,8 @@ fill_default_options(Options * options) options->ip_qos_bulk = IPTOS_THROUGHPUT; if (options->request_tty == -1) options->request_tty = REQUEST_TTY_AUTO; + if (options->proxy_use_fdpass == -1) + options->proxy_use_fdpass = 0; /* options->local_command should not be set by default */ /* options->proxy_command should not be set by default */ /* options->user will be set in the main program if appropriate */ diff --git a/readconf.h b/readconf.h index 23fc500da..ca4a042ad 100644 --- a/readconf.h +++ b/readconf.h @@ -1,4 +1,4 @@ -/* $OpenBSD: readconf.h,v 1.95 2013/05/16 04:27:50 djm Exp $ */ +/* $OpenBSD: readconf.h,v 1.96 2013/08/20 00:11:38 djm Exp $ */ /* * Author: Tatu Ylonen @@ -138,6 +138,8 @@ typedef struct { int request_tty; + int proxy_use_fdpass; + char *ignored_unknown; /* Pattern list of unknown tokens to ignore */ } Options; diff --git a/ssh_config.5 b/ssh_config.5 index 5d76c6d2d..e89d694c7 100644 --- a/ssh_config.5 +++ b/ssh_config.5 @@ -33,8 +33,8 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.\" $OpenBSD: ssh_config.5,v 1.166 2013/06/27 14:05:37 jmc Exp $ -.Dd $Mdocdate: June 27 2013 $ +.\" $OpenBSD: ssh_config.5,v 1.167 2013/08/20 00:11:38 djm Exp $ +.Dd $Mdocdate: August 20 2013 $ .Dt SSH_CONFIG 5 .Os .Sh NAME @@ -937,6 +937,14 @@ For example, the following directive would connect via an HTTP proxy at .Bd -literal -offset 3n ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p .Ed +.It Cm ProxyUseFdpass +Specifies that the a +.Cm ProxyCommand +will pass a connected file descriptor back to +.Nm ssh +instead of continuing to execute and pass data. +The default is +.Dq no . .It Cm PubkeyAuthentication Specifies whether to try public key authentication. The argument to this keyword must be diff --git a/sshconnect.c b/sshconnect.c index 483eb85ac..76bb5cdac 100644 --- a/sshconnect.c +++ b/sshconnect.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshconnect.c,v 1.238 2013/05/17 00:13:14 djm Exp $ */ +/* $OpenBSD: sshconnect.c,v 1.239 2013/08/20 00:11:38 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -59,6 +59,7 @@ #include "misc.h" #include "dns.h" #include "roaming.h" +#include "monitor_fdpass.h" #include "ssh2.h" #include "version.h" @@ -78,16 +79,113 @@ extern uid_t original_effective_uid; static int show_other_keys(struct hostkeys *, Key *); static void warn_changed_key(Key *); +/* Expand a proxy command */ +static char * +expand_proxy_command(const char *proxy_command, const char *user, + const char *host, int port) +{ + char *tmp, *ret, strport[NI_MAXSERV]; + + snprintf(strport, sizeof strport, "%hu", port); + xasprintf(&tmp, "exec %s", proxy_command); + ret = percent_expand(tmp, "h", host, "p", strport, + "r", options.user, (char *)NULL); + free(tmp); + return ret; +} + +/* + * Connect to the given ssh server using a proxy command that passes a + * a connected fd back to us. + */ +static int +ssh_proxy_fdpass_connect(const char *host, u_short port, + const char *proxy_command) +{ + char *command_string; + int sp[2], sock; + pid_t pid; + char *shell; + + if ((shell = getenv("SHELL")) == NULL) + shell = _PATH_BSHELL; + + if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) + fatal("Could not create socketpair to communicate with " + "proxy dialer: %.100s", strerror(errno)); + + command_string = expand_proxy_command(proxy_command, options.user, + host, port); + debug("Executing proxy dialer command: %.500s", command_string); + + /* Fork and execute the proxy command. */ + if ((pid = fork()) == 0) { + char *argv[10]; + + /* Child. Permanently give up superuser privileges. */ + permanently_drop_suid(original_real_uid); + + close(sp[1]); + /* Redirect stdin and stdout. */ + if (sp[0] != 0) { + if (dup2(sp[0], 0) < 0) + perror("dup2 stdin"); + } + if (sp[0] != 1) { + if (dup2(sp[0], 1) < 0) + perror("dup2 stdout"); + } + if (sp[0] >= 2) + close(sp[0]); + + /* + * Stderr is left as it is so that error messages get + * printed on the user's terminal. + */ + argv[0] = shell; + argv[1] = "-c"; + argv[2] = command_string; + argv[3] = NULL; + + /* + * Execute the proxy command. + * Note that we gave up any extra privileges above. + */ + execv(argv[0], argv); + perror(argv[0]); + exit(1); + } + /* Parent. */ + if (pid < 0) + fatal("fork failed: %.100s", strerror(errno)); + close(sp[0]); + free(command_string); + + if ((sock = mm_receive_fd(sp[1])) == -1) + fatal("proxy dialer did not pass back a connection"); + + while (waitpid(pid, NULL, 0) == -1) + if (errno != EINTR) + fatal("Couldn't wait for child: %s", strerror(errno)); + + /* Set the connection file descriptors. */ + packet_set_connection(sock, sock); + packet_set_timeout(options.server_alive_interval, + options.server_alive_count_max); + + return 0; +} + /* * Connect to the given ssh server using a proxy command. */ static int ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) { - char *command_string, *tmp; + char *command_string; int pin[2], pout[2]; pid_t pid; - char *shell, strport[NI_MAXSERV]; + char *shell; if (!strcmp(proxy_command, "-")) { packet_set_connection(STDIN_FILENO, STDOUT_FILENO); @@ -96,29 +194,19 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) return 0; } + if (options.proxy_use_fdpass) + return ssh_proxy_fdpass_connect(host, port, proxy_command); + if ((shell = getenv("SHELL")) == NULL || *shell == '\0') shell = _PATH_BSHELL; - /* Convert the port number into a string. */ - snprintf(strport, sizeof strport, "%hu", port); - - /* - * Build the final command string in the buffer by making the - * appropriate substitutions to the given proxy command. - * - * Use "exec" to avoid "sh -c" processes on some platforms - * (e.g. Solaris) - */ - xasprintf(&tmp, "exec %s", proxy_command); - command_string = percent_expand(tmp, "h", host, "p", strport, - "r", options.user, (char *)NULL); - free(tmp); - /* Create pipes for communicating with the proxy. */ if (pipe(pin) < 0 || pipe(pout) < 0) fatal("Could not create pipes to communicate with the proxy: %.100s", strerror(errno)); + command_string = expand_proxy_command(proxy_command, options.user, + host, port); debug("Executing proxy command: %.500s", command_string); /* Fork and execute the proxy command. */