openssh-5.9p1-authorized-keys-script.diff

diff -ru openssh-5.9p1/auth2-pubkey.c openssh-5.9p1-patched/auth2-pubkey.c
--- openssh-5.9p1/auth2-pubkey.c	2011-05-29 20:39:38.000000000 +0900
+++ openssh-5.9p1-patched/auth2-pubkey.c	2012-01-04 09:35:21.099076049 +0900
@@ -432,6 +432,97 @@
 	return ret;
 }
 
+/* check to see if the script specified by file can authorize the key
+ *
+ * the script will have the key written to STDIN, which is identical
+ * to the normal public key format.
+ *
+ * the script must exit with either 0 for success or 1 for failure.
+ * the script can print login options (if any) to STDOUT. No whitepace should be added
+ * to the output.
+ *
+ * Use with caution: the script can hang sshd. It is recommended you code the script
+ * with a timeout set if it cannot determine authenication quickly.
+ */
+static int
+user_key_found_by_script(struct passwd *pw, Key *key, char *file)
+{
+	pid_t pid;
+	char line[SSH_MAX_PUBKEY_BYTES];
+	int pipe_in[2];
+	int pipe_out[2];
+	int exit_code = 1;
+	int success = 0;
+	FILE *f;
+	//mysig_t oldsig;
+
+	pipe(pipe_in);
+	pipe(pipe_out);
+
+	//oldsig = signal(SIGCHLD, SIG_IGN);
+	temporarily_use_uid(pw);
+
+	debug3("user_key_found_by_script: executing %s", file);
+
+	switch ((pid = fork())) {
+	case -1:
+		error("fork(): %s", strerror(errno));
+		restore_uid();
+		return (-1);
+	case 0:
+		/* setup input pipe */
+		close(pipe_in[1]);
+		dup2(pipe_in[0], 0);
+		close(pipe_in[0]);
+
+		/* setup output pipe */
+		close(pipe_out[0]);
+		dup2(pipe_out[1], 1);
+		close(pipe_out[1]);
+
+		execl(file, file, NULL);
+
+		/* exec failed */
+		error("execl(): %s", strerror(errno));
+		_exit(1);
+	default:
+		debug3("user_key_found_by_script: script pid %d", pid);
+
+		close(pipe_in[0]);
+		close(pipe_out[1]);
+
+		f = fdopen(pipe_in[1], "w");
+		key_write(key, f);
+		fclose(f);
+
+		while(waitpid(pid, &exit_code, 0) < 0) {
+			switch(errno) {
+			case EINTR:
+				debug3("user_key_found_by_script: waitpid() EINTR, continuing");
+				continue;
+			default:
+				error("waitpid(): %s", strerror(errno));
+				goto waitpid_error;
+			}
+		}
+		if (WIFEXITED(exit_code) && WEXITSTATUS(exit_code) == 0) {
+			int amt_read = read(pipe_out[0], line, sizeof(line) - 1);
+			line[amt_read] = ' ';
+			line[amt_read + 1] = 0;
+			debug3("user_key_found_by_script: options: %s", line);
+			if (auth_parse_options(pw, line, file, 0) == 1)
+				success = 1;
+		}
+	 waitpid_error:
+		close(pipe_out[0]);
+	}
+
+	restore_uid();
+	//signal(SIGCHLD, oldsig);
+
+	return success;
+}
+
 /* check whether given key is in .ssh/authorized_keys* */
 int
 user_key_allowed(struct passwd *pw, Key *key)
@@ -453,8 +544,16 @@
 		    options.authorized_keys_files[i], pw);
 		success = user_key_allowed2(pw, key, file);
 		xfree(file);
+                if (success)
+                    return success;
 	}
 
+        /* try the script to find the key */
+        if ((file = authorized_keys_script(pw))) {
+            success = user_key_found_by_script(pw, key, file);
+            xfree(file);
+        }
+
 	return success;
 }
 
diff -ru openssh-5.9p1/auth.c openssh-5.9p1-patched/auth.c
--- openssh-5.9p1/auth.c	2011-05-29 20:40:42.000000000 +0900
+++ openssh-5.9p1-patched/auth.c	2012-01-04 09:31:10.925075597 +0900
@@ -362,6 +362,15 @@
 	return expand_authorized_keys(options.authorized_principals_file, pw);
 }
 
+char *
+authorized_keys_script(struct passwd *pw)
+{
+	if (options.authorized_keys_script)
+		return expand_authorized_keys(options.authorized_keys_script, pw);
+	else
+		return NULL;
+}
+
 /* return ok if key exists in sysfile or userfile */
 HostStatus
 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
diff -ru openssh-5.9p1/auth.h openssh-5.9p1-patched/auth.h
--- openssh-5.9p1/auth.h	2011-05-29 20:39:38.000000000 +0900
+++ openssh-5.9p1-patched/auth.h	2012-01-04 09:36:29.228079132 +0900
@@ -170,6 +170,7 @@
 
 char	*expand_authorized_keys(const char *, struct passwd *pw);
 char	*authorized_principals_file(struct passwd *);
+char	*authorized_keys_script(struct passwd *);
 
 FILE	*auth_openkeyfile(const char *, struct passwd *, int);
 FILE	*auth_openprincipals(const char *, struct passwd *, int);
diff -ru openssh-5.9p1/servconf.c openssh-5.9p1-patched/servconf.c
--- openssh-5.9p1/servconf.c	2011-06-23 07:30:03.000000000 +0900
+++ openssh-5.9p1-patched/servconf.c	2012-01-04 09:39:45.280074926 +0900
@@ -136,6 +136,7 @@
 	options->revoked_keys_file = NULL;
 	options->trusted_user_ca_keys = NULL;
 	options->authorized_principals_file = NULL;
+	options->authorized_keys_script = NULL;
 	options->ip_qos_interactive = -1;
 	options->ip_qos_bulk = -1;
 }
@@ -318,6 +319,7 @@
 	sBanner, sUseDNS, sHostbasedAuthentication,
 	sHostbasedUsesNameFromPacketOnly, sClientAliveInterval,
 	sClientAliveCountMax, sAuthorizedKeysFile,
+	sAuthorizedKeysScript,
 	sGssAuthentication, sGssCleanupCreds, sAcceptEnv, sPermitTunnel,
 	sMatch, sPermitOpen, sForceCommand, sChrootDirectory,
 	sUsePrivilegeSeparation, sAllowAgentForwarding,
@@ -435,6 +437,7 @@
 	{ "clientalivecountmax", sClientAliveCountMax, SSHCFG_GLOBAL },
 	{ "authorizedkeysfile", sAuthorizedKeysFile, SSHCFG_ALL },
 	{ "authorizedkeysfile2", sDeprecated, SSHCFG_ALL },
+	{ "authorizedkeysscript", sAuthorizedKeysScript, SSHCFG_ALL },
 	{ "useprivilegeseparation", sUsePrivilegeSeparation, SSHCFG_GLOBAL},
 	{ "acceptenv", sAcceptEnv, SSHCFG_GLOBAL },
 	{ "permittunnel", sPermitTunnel, SSHCFG_ALL },
@@ -1267,6 +1270,10 @@
 		}
 		break;
 
+	case sAuthorizedKeysScript:
+		charptr = &options->authorized_keys_script;
+		goto parse_filename;
+
 	case sClientAliveInterval:
 		intptr = &options->client_alive_interval;
 		goto parse_time;
@@ -1758,6 +1765,7 @@
 	dump_cfg_string(sRevokedKeys, o->revoked_keys_file);
 	dump_cfg_string(sAuthorizedPrincipalsFile,
 	    o->authorized_principals_file);
+	dump_cfg_string(sAuthorizedKeysScript, o->authorized_keys_script);
 
 	/* string arguments requiring a lookup */
 	dump_cfg_string(sLogLevel, log_level_name(o->log_level));
diff -ru openssh-5.9p1/servconf.h openssh-5.9p1-patched/servconf.h
--- openssh-5.9p1/servconf.h	2011-06-23 07:30:03.000000000 +0900
+++ openssh-5.9p1-patched/servconf.h	2012-01-04 09:31:10.928076038 +0900
@@ -154,6 +154,8 @@
 	u_int num_authkeys_files;	/* Files containing public keys */
 	char   *authorized_keys_files[MAX_AUTHKEYS_FILES];
 
+	char   *authorized_keys_script;
+
 	char   *adm_forced_command;
 
 	int	use_pam;		/* Enable auth via PAM */