- djm@cvs.openbsd.org 2004/06/24 19:30:54

     [servconf.c servconf.h sshd.c]
     re-exec sshd on accept(); initial work, final debugging and ok markus@

4 files changed, 261 insertions, 32 deletions

diff --git a/ChangeLog b/ChangeLog
index 023fde0cd..4367699d2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+20040625
+ - (dtucker) OpenBSD CVS Sync
+   - djm@cvs.openbsd.org 2004/06/24 19:30:54
+     [servconf.c servconf.h sshd.c]
+     re-exec sshd on accept(); initial work, final debugging and ok markus@
+
 20040623
  - (dtucker) [auth1.c] Ensure do_pam_account is called for Protocol 1
    connections with empty passwords.  Patch from davidwu at nbttech.com,
@@ -1399,4 +1405,4 @@
    - (djm) Trim deprecated options from INSTALL. Mention UsePAM
    - (djm) Fix quote handling in sftp; Patch from admorten AT umich.edu
 
-$Id: ChangeLog,v 1.3443 2004/06/23 14:34:53 dtucker Exp $
+$Id: ChangeLog,v 1.3444 2004/06/25 03:33:20 dtucker Exp $
diff --git a/servconf.c b/servconf.c
index ef8651651..ea67f6288 100644
--- a/servconf.c
+++ b/servconf.c
@@ -10,7 +10,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: servconf.c,v 1.133 2004/05/23 23:59:53 dtucker Exp $");
+RCSID("$OpenBSD: servconf.c,v 1.134 2004/06/24 19:30:54 djm Exp $");
 
 #include "ssh.h"
 #include "log.h"
@@ -942,26 +942,50 @@ parse_flag:
 /* Reads the server configuration file. */
 
 void
-read_server_config(ServerOptions *options, const char *filename)
+load_server_config(const char *filename, Buffer *conf)
 {
-        int linenum, bad_options = 0;
-        char line[1024];
+        char line[1024], *cp;
         FILE *f;
 
-        debug2("read_server_config: filename %s", filename);
-        f = fopen(filename, "r");
-        if (!f) {
+        debug2("%s: filename %s", __func__, filename);
+        if ((f = fopen(filename, "r")) == NULL) {
                 perror(filename);
                 exit(1);
         }
-        linenum = 0;
+        buffer_clear(conf);
         while (fgets(line, sizeof(line), f)) {
-                /* Update line number counter. */
-                linenum++;
-                if (process_server_config_line(options, line, filename, linenum) != 0)
-                        bad_options++;
+                /*
+                 * Trim out comments and strip whitespace
+                 * NB - preserve newlines, they are needed to reproduce 
+                 * line numbers later for error messages
+                 */
+                if ((cp = strchr(line, '#')) != NULL)
+                        memcpy(cp, "\n", 2);
+                cp = line + strspn(line, " \t\r");
+
+                buffer_append(conf, cp, strlen(cp));
         }
+        buffer_append(conf, "\0", 1);
         fclose(f);
+        debug2("%s: done config len = %d", __func__, buffer_len(conf));
+}
+
+void
+parse_server_config(ServerOptions *options, const char *filename, Buffer *conf)
+{
+        int linenum, bad_options = 0;
+        char *cp, *cbuf;
+
+        debug2("%s: config %s len %d", __func__, filename, buffer_len(conf));
+
+        cbuf = xstrdup(buffer_ptr(conf));
+        linenum = 0;
+        while((cp = strsep(&cbuf, "\n")) != NULL) {
+                if (process_server_config_line(options, cp, filename,
+                    linenum++) != 0)
+                        bad_options++;
+        }
+        free(cbuf);
         if (bad_options > 0)
                 fatal("%s: terminating, %d bad configuration options",
                     filename, bad_options);
diff --git a/servconf.h b/servconf.h
index 36d2e5ca6..ebd056814 100644
--- a/servconf.h
+++ b/servconf.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: servconf.h,v 1.69 2004/05/23 23:59:53 dtucker Exp $   */
+/*      $OpenBSD: servconf.h,v 1.70 2004/06/24 19:30:54 djm Exp $       */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -16,6 +16,8 @@
 #ifndef SERVCONF_H
 #define SERVCONF_H
 
+#include "buffer.h"
+
 #define MAX_PORTS               256     /* Max # ports. */
 
 #define MAX_ALLOW_USERS         256     /* Max # users on allow list. */
@@ -134,9 +136,9 @@ typedef struct {
 }       ServerOptions;
 
 void     initialize_server_options(ServerOptions *);
-void     read_server_config(ServerOptions *, const char *);
 void     fill_default_server_options(ServerOptions *);
 int      process_server_config_line(ServerOptions *, char *, const char *, int);
-
+void     load_server_config(const char *, Buffer *);
+void     parse_server_config(ServerOptions *, const char *, Buffer *);
 
 #endif                          /* SERVCONF_H */
diff --git a/sshd.c b/sshd.c
index 34379172f..98e90b5ac 100644
--- a/sshd.c
+++ b/sshd.c
@@ -42,7 +42,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshd.c,v 1.293 2004/06/14 01:44:39 djm Exp $");
+RCSID("$OpenBSD: sshd.c,v 1.294 2004/06/24 19:30:54 djm Exp $");
 
 #include <openssl/dh.h>
 #include <openssl/bn.h>
@@ -65,6 +65,7 @@ RCSID("$OpenBSD: sshd.c,v 1.293 2004/06/14 01:44:39 djm Exp $");
 #include "uidswap.h"
 #include "compat.h"
 #include "buffer.h"
+#include "bufaux.h"
 #include "cipher.h"
 #include "kex.h"
 #include "key.h"
@@ -76,6 +77,7 @@ RCSID("$OpenBSD: sshd.c,v 1.293 2004/06/14 01:44:39 djm Exp $");
 #include "canohost.h"
 #include "auth.h"
 #include "misc.h"
+#include "msg.h"
 #include "dispatch.h"
 #include "channels.h"
 #include "session.h"
@@ -137,6 +139,12 @@ int log_stderr = 0;
 char **saved_argv;
 int saved_argc;
 
+/* re-exec */
+int rexeced_flag = 0;
+int rexec_flag = 1;
+int rexec_argc = 0;
+char **rexec_argv;
+
 /*
  * The sockets that the server is listening; this is used in the SIGHUP
  * signal handler.
@@ -771,6 +779,87 @@ usage(void)
         exit(1);
 }
 
+static void
+send_rexec_state(int fd, Buffer *conf)
+{
+        Buffer m;
+
+        debug3("%s: entering fd = %d config len %d", __func__, fd,
+            buffer_len(conf));
+
+        /*
+         * Protocol from reexec master to child:
+         *      string  configuration
+         *      u_int   ephemeral_key_follows
+         *      bignum  e               (only if ephemeral_key_follows == 1)
+         *      bignum  n                       "
+         *      bignum  d                       "
+         *      bignum  iqmp                    "
+         *      bignum  p                       "
+         *      bignum  q                       "
+         */
+        buffer_init(&m);
+        buffer_put_cstring(&m, buffer_ptr(conf));
+
+        if (sensitive_data.server_key != NULL && 
+            sensitive_data.server_key->type == KEY_RSA1) {
+                buffer_put_int(&m, 1);
+                buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
+                buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
+                buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
+                buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
+                buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
+                buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
+        } else
+                buffer_put_int(&m, 0);
+
+        if (ssh_msg_send(fd, 0, &m) == -1)
+                fatal("%s: ssh_msg_send failed", __func__);
+
+        buffer_free(&m);
+
+        debug3("%s: done", __func__);
+}
+
+static void
+recv_rexec_state(int fd, Buffer *conf)
+{
+        Buffer m;
+        char *cp;
+        u_int len;
+
+        debug3("%s: entering fd = %d", __func__, fd);
+
+        buffer_init(&m);
+
+        if (ssh_msg_recv(fd, &m) == -1)
+                fatal("%s: ssh_msg_recv failed", __func__);
+        if (buffer_get_char(&m) != 0)
+                fatal("%s: rexec version mismatch", __func__);
+
+        cp = buffer_get_string(&m, &len);
+        if (conf != NULL)
+                buffer_append(conf, cp, len + 1);
+        xfree(cp);
+
+        if (buffer_get_int(&m)) {
+                if (sensitive_data.server_key != NULL)
+                        key_free(sensitive_data.server_key);
+                sensitive_data.server_key = key_new_private(KEY_RSA1);
+                buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
+                buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
+                buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
+                buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
+                buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
+                buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
+                rsa_generate_additional_parameters(
+                    sensitive_data.server_key->rsa);
+        }
+        buffer_free(&m);
+
+        debug3("%s: done", __func__);
+}
+
 /*
  * Main program for the daemon.
  */
@@ -791,11 +880,12 @@ main(int ac, char **av)
         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
         char *line;
         int listen_sock, maxfd;
-        int startup_p[2];
+        int startup_p[2], config_s[2];
         int startups = 0;
         Key *key;
         Authctxt *authctxt;
         int ret, key_used = 0;
+        Buffer cfg;
 
 #ifdef HAVE_SECUREWARE
         (void)set_auth_parameters(ac, av);
@@ -823,7 +913,7 @@ main(int ac, char **av)
         initialize_server_options(&options);
 
         /* Parse command-line arguments. */
-        while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqtQ46")) != -1) {
+        while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
                 switch (opt) {
                 case '4':
                         IPv4or6 = AF_INET;
@@ -850,6 +940,13 @@ main(int ac, char **av)
                 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;
@@ -913,6 +1010,13 @@ main(int ac, char **av)
                         break;
                 }
         }
+        if (rexeced_flag || inetd_flag)
+                rexec_flag = 0;
+        if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
+                fatal("sshd re-exec requires execution with an absolute path");
+        if (rexeced_flag)
+                closefrom(STDERR_FILENO + 3);
+
         SSLeay_add_all_algorithms();
         channel_set_af(IPv4or6);
 
@@ -943,8 +1047,23 @@ main(int ac, char **av)
 
         seed_rng();
 
-        /* Read server configuration options from the configuration file. */
-        read_server_config(&options, config_file_name);
+        sensitive_data.server_key = NULL;
+        sensitive_data.ssh1_host_key = NULL;
+        sensitive_data.have_ssh1_key = 0;
+        sensitive_data.have_ssh2_key = 0;
+
+        /* Fetch our configuration */
+        buffer_init(&cfg);
+        if (rexeced_flag)
+                recv_rexec_state(STDERR_FILENO + 2, &cfg);
+        else
+                load_server_config(config_file_name, &cfg);
+
+        parse_server_config(&options,
+            rexeced_flag ? "rexec" : config_file_name, &cfg);
+
+        if (!rexec_flag)
+                buffer_free(&cfg);
 
         /* Fill in default values for those options not explicitly set. */
         fill_default_server_options(&options);
@@ -962,10 +1081,6 @@ main(int ac, char **av)
             sizeof(Key *));
         for (i = 0; i < options.num_host_key_files; i++)
                 sensitive_data.host_keys[i] = NULL;
-        sensitive_data.server_key = NULL;
-        sensitive_data.ssh1_host_key = NULL;
-        sensitive_data.have_ssh1_key = 0;
-        sensitive_data.have_ssh2_key = 0;
 
         for (i = 0; i < options.num_host_key_files; i++) {
                 key = key_load_private(options.host_key_files[i], "", NULL);
@@ -1064,6 +1179,16 @@ main(int ac, char **av)
         if (setgroups(0, NULL) < 0)
                 debug("setgroups() failed: %.200s", strerror(errno));
 
+        if (rexec_flag) {
+                rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
+                for (i = 0; i < 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;
+        }
+
         /* Initialize the log (it is reinitialized below in case we forked). */
         if (debug_flag && !inetd_flag)
                 log_stderr = 1;
@@ -1105,19 +1230,34 @@ main(int ac, char **av)
 
         /* Start listening for a socket, unless started from inetd. */
         if (inetd_flag) {
-                int s1;
-                s1 = dup(0);    /* Make sure descriptors 0, 1, and 2 are in use. */
-                dup(s1);
-                sock_in = dup(0);
-                sock_out = dup(1);
+                int fd;
+
                 startup_pipe = -1;
+                if (rexeced_flag) {
+                        close(STDERR_FILENO + 2);
+                        sock_in = sock_out = dup(STDIN_FILENO);
+                        if (!debug_flag) {
+                                startup_pipe = dup(STDERR_FILENO + 1);
+                                close(STDERR_FILENO + 1);
+                        }
+                } 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
+                 * 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 (fd > STDOUT_FILENO)
+                                close(fd);
+                }
                 debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
-                if (options.protocol & SSH_PROTO_1)
+                if ((options.protocol & SSH_PROTO_1) &&
+                    sensitive_data.server_key == NULL)
                         generate_ephemeral_server_key();
         } else {
                 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
@@ -1297,6 +1437,16 @@ main(int ac, char **av)
                                         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];
@@ -1320,8 +1470,15 @@ main(int ac, char **av)
                                         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;
                                 } else {
                                         /*
@@ -1355,6 +1512,12 @@ main(int ac, char **av)
 
                                 close(startup_p[1]);
 
+                                if (rexec_flag) {
+                                        send_rexec_state(config_s[0], &cfg);
+                                        close(config_s[0]);
+                                        close(config_s[1]);
+                                }
+
                                 /* Mark that the key has been used (it was "given" to the child). */
                                 if ((options.protocol & SSH_PROTO_1) &&
                                     key_used == 0) {
@@ -1378,6 +1541,40 @@ main(int ac, char **av)
         /* This is the child processing a new connection. */
         setproctitle("%s", "[accepted]");
 
+        if (rexec_flag) {
+                int fd;
+
+                debug("rexec newsock %d pipe %d sock %d", newsock, 
+                    startup_pipe, config_s[0]);
+                dup2(newsock, STDIN_FILENO);
+                dup2(STDIN_FILENO, STDOUT_FILENO);
+                if (startup_pipe == -1)
+                        close(STDERR_FILENO + 1);
+                else
+                        dup2(startup_pipe, STDERR_FILENO + 1);
+
+                dup2(config_s[1], STDERR_FILENO + 2);
+                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(STDERR_FILENO + 2, NULL);
+                log_init(__progname, options.log_level,
+                    options.log_facility, log_stderr);
+
+                /* Clean up fds */
+                close(config_s[1]);
+                close(STDERR_FILENO + 1);
+                close(STDERR_FILENO + 2);
+                if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
+                        dup2(fd, STDIN_FILENO);
+                        dup2(fd, STDOUT_FILENO);
+                        if (fd > STDERR_FILENO)
+                                close(fd);
+                }
+        }
+
         /*
          * Create a new session and process group since the 4.4BSD
          * setlogin() affects the entire process group.  We don't