openssh/openssh-5.4p1-pka.patch

diff -up openssh-5.4p1/auth2-pubkey.c.pka openssh-5.4p1/auth2-pubkey.c
--- openssh-5.4p1/auth2-pubkey.c.pka	2010-03-01 18:10:48.000000000 +0100
+++ openssh-5.4p1/auth2-pubkey.c	2010-03-01 18:10:50.000000000 +0100
@@ -186,27 +186,15 @@ done:
 
 /* return 1 if user allows given key */
 static int
-user_key_allowed2(struct passwd *pw, Key *key, char *file)
+user_search_key_in_file(FILE *f, char *file, Key* key, struct passwd *pw)
 {
 	char line[SSH_MAX_PUBKEY_BYTES];
 	const char *reason;
 	int found_key = 0;
-	FILE *f;
 	u_long linenum = 0;
 	Key *found;
 	char *fp;
 
-	/* Temporarily use the user's uid. */
-	temporarily_use_uid(pw);
-
-	debug("trying public key file %s", file);
-	f = auth_openkeyfile(file, pw, options.strict_modes);
-
-	if (!f) {
-		restore_uid();
-		return 0;
-	}
-
 	found_key = 0;
 	found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
 
@@ -277,21 +265,160 @@ user_key_allowed2(struct passwd *pw, Key
 			break;
 		}
 	}
-	restore_uid();
-	fclose(f);
 	key_free(found);
 	if (!found_key)
 		debug2("key not found");
 	return found_key;
 }
 
-/* check whether given key is in .ssh/authorized_keys* */
+
+/* return 1 if user allows given key */
+static int
+user_key_allowed2(struct passwd *pw, Key *key, char *file)
+{
+	FILE *f;
+	int found_key = 0;
+
+	/* Temporarily use the user's uid. */
+	temporarily_use_uid(pw);
+
+	debug("trying public key file %s", file);
+	f = auth_openkeyfile(file, pw, options.strict_modes);
+
+ 	if (f) {
+ 		found_key = user_search_key_in_file (f, file, key, pw);
+		fclose(f);
+	}
+
+	restore_uid();
+	return found_key;
+}
+
+#ifdef WITH_PUBKEY_AGENT
+
+#define WHITESPACE " \t\r\n"
+
+/* return 1 if user allows given key */
+static int
+user_key_via_agent_allowed2(struct passwd *pw, Key *key)
+{
+	FILE *f;
+	int found_key = 0;
+	char *pubkey_agent_string = NULL;
+	char *tmp_pubkey_agent_string = NULL;
+	char *progname;
+	char *cp;
+	struct passwd *runas_pw;
+	struct stat st;
+
+	if (options.pubkey_agent == NULL || options.pubkey_agent[0] != '/')
+		return -1;
+
+	/* get the run as identity from config */
+	runas_pw = (options.pubkey_agent_runas == NULL)? pw
+	    : getpwnam (options.pubkey_agent_runas);
+	if (!runas_pw) {
+		error("%s: getpwnam(\"%s\"): %s", __func__,
+		    options.pubkey_agent_runas, strerror(errno));
+		return 0;
+	}
+
+	/* Temporarily use the specified uid. */
+	if (runas_pw->pw_uid != 0)
+		temporarily_use_uid(runas_pw);
+
+	pubkey_agent_string = percent_expand(options.pubkey_agent,
+	    "h", pw->pw_dir, "u", pw->pw_name, (char *)NULL);
+
+	/* Test whether agent can be modified by non root user */
+	tmp_pubkey_agent_string = xstrdup (pubkey_agent_string);
+	progname = strtok (tmp_pubkey_agent_string, WHITESPACE);
+
+	debug3("%s: checking program '%s'", __func__, progname);
+
+	if (stat (progname, &st) < 0) {
+		error("%s: stat(\"%s\"): %s", __func__,
+		    progname, strerror(errno));
+		goto go_away;
+	}
+
+	if (st.st_uid != 0 || (st.st_mode & 022) != 0) {
+		error("bad ownership or modes for pubkey agent \"%s\"",
+		    progname);
+		goto go_away;
+	}
+
+	if (!S_ISREG(st.st_mode)) {
+		error("pubkey agent \"%s\" is not a regular file",
+		    progname);
+		goto go_away;
+	}
+
+	/*
+	 * Descend the path, checking that each component is a
+	 * root-owned directory with strict permissions.
+	 */
+	do {
+		if ((cp = strrchr(progname, '/')) == NULL)
+			break;
+		else 
+			*cp = '\0';
+	
+		debug3("%s: checking component '%s'", __func__, progname);
+
+		if (stat(progname, &st) != 0) {
+			error("%s: stat(\"%s\"): %s", __func__,
+			    progname, strerror(errno));
+			goto go_away;
+		}
+		if (st.st_uid != 0 || (st.st_mode & 022) != 0) {
+			error("bad ownership or modes for pubkey agent path component \"%s\"",
+			    progname);
+			goto go_away;
+		}
+		if (!S_ISDIR(st.st_mode)) {
+			error("pubkey agent path component \"%s\" is not a directory",
+			    progname);
+			goto go_away;
+		}
+	} while (0);
+
+	/* open the pipe and read the keys */
+	f = popen (pubkey_agent_string, "r");
+	if (!f) {
+		error("%s: popen (\"%s\", \"r\"): %s", __func__,
+		    pubkey_agent_string, strerror (errno));
+		goto go_away;
+	}
+
+	found_key = user_search_key_in_file (f, options.pubkey_agent, key, pw);
+	pclose (f);
+
+go_away:
+	if (tmp_pubkey_agent_string)
+		xfree (tmp_pubkey_agent_string);
+	if (pubkey_agent_string)
+		xfree (pubkey_agent_string);
+
+	if (runas_pw->pw_uid != 0)
+		restore_uid();
+	return found_key;
+}
+#endif
+
+/* check whether given key is in <pkey_agent or .ssh/authorized_keys* */
 int
 user_key_allowed(struct passwd *pw, Key *key)
 {
 	int success;
 	char *file;
 
+#ifdef WITH_PUBKEY_AGENT
+	success = user_key_via_agent_allowed2(pw, key);
+	if (success >= 0)
+		return success;
+#endif
+
 	file = authorized_keys_file(pw);
 	success = user_key_allowed2(pw, key, file);
 	xfree(file);
diff -up openssh-5.4p1/configure.ac.pka openssh-5.4p1/configure.ac
--- openssh-5.4p1/configure.ac.pka	2010-03-01 18:10:47.000000000 +0100
+++ openssh-5.4p1/configure.ac	2010-03-01 18:10:50.000000000 +0100
@@ -1323,6 +1323,18 @@ AC_ARG_WITH(audit,
 	esac ]
 )
 
+# Check whether user wants pubkey agent support
+PKA_MSG="no"
+AC_ARG_WITH(pka,
+	[  --with-pka      Enable pubkey agent support],
+	[
+		if test "x$withval" != "xno" ; then
+			AC_DEFINE([WITH_PUBKEY_AGENT], 1, [Enable pubkey agent support])
+			PKA_MSG="yes"
+		fi
+	]
+)
+
 dnl    Checks for library functions. Please keep in alphabetical order
 AC_CHECK_FUNCS( \
 	arc4random \
@@ -4206,6 +4218,7 @@ echo "               Linux audit support
 echo "                 Smartcard support: $SCARD_MSG"
 echo "                     S/KEY support: $SKEY_MSG"
 echo "              TCP Wrappers support: $TCPW_MSG"
+echo "                       PKA support: $PKA_MSG"
 echo "              MD5 password support: $MD5_MSG"
 echo "                   libedit support: $LIBEDIT_MSG"
 echo "  Solaris process contract support: $SPC_MSG"
diff -up openssh-5.4p1/servconf.c.pka openssh-5.4p1/servconf.c
--- openssh-5.4p1/servconf.c.pka	2010-03-01 18:10:46.000000000 +0100
+++ openssh-5.4p1/servconf.c	2010-03-01 18:13:23.000000000 +0100
@@ -129,6 +129,8 @@ initialize_server_options(ServerOptions 
 	options->num_permitted_opens = -1;
 	options->adm_forced_command = NULL;
 	options->chroot_directory = NULL;
+	options->pubkey_agent = NULL;
+	options->pubkey_agent_runas = NULL;
 	options->zero_knowledge_password_authentication = -1;
 }
 
@@ -312,6 +314,7 @@ typedef enum {
 	sMatch, sPermitOpen, sForceCommand, sChrootDirectory,
 	sUsePrivilegeSeparation, sAllowAgentForwarding,
 	sZeroKnowledgePasswordAuthentication, sHostCertificate,
+	sPubkeyAgent, sPubkeyAgentRunAs,
 	sDeprecated, sUnsupported
 } ServerOpCodes;
 
@@ -432,6 +435,13 @@ static struct {
 	{ "forcecommand", sForceCommand, SSHCFG_ALL },
 	{ "chrootdirectory", sChrootDirectory, SSHCFG_ALL },
 	{ "hostcertificate", sHostCertificate, SSHCFG_GLOBAL },
+#ifdef WITH_PUBKEY_AGENT
+	{ "pubkeyagent", sPubkeyAgent, SSHCFG_ALL },
+	{ "pubkeyagentrunas", sPubkeyAgentRunAs, SSHCFG_ALL },
+#else
+	{ "pubkeyagent", sUnsupported, SSHCFG_ALL },
+	{ "pubkeyagentrunas", sUnsupported, SSHCFG_ALL },
+#endif
 	{ NULL, sBadOption, 0 }
 };
 
@@ -1332,6 +1342,20 @@ process_server_config_line(ServerOptions
 			*charptr = xstrdup(arg);
 		break;
 
+	case sPubkeyAgent:
+		len = strspn(cp, WHITESPACE);
+		if (*activep && options->pubkey_agent == NULL)
+			options->pubkey_agent = xstrdup(cp + len);
+		return 0;
+
+	case sPubkeyAgentRunAs:
+		charptr = &options->pubkey_agent_runas;
+
+		arg = strdelim(&cp);
+		if (*activep && *charptr == NULL)
+			*charptr = xstrdup(arg);
+		break;
+
 	case sDeprecated:
 		logit("%s line %d: Deprecated option %s",
 		    filename, linenum, arg);
@@ -1425,6 +1449,8 @@ copy_set_server_options(ServerOptions *d
 	M_CP_INTOPT(gss_authentication);
 	M_CP_INTOPT(rsa_authentication);
 	M_CP_INTOPT(pubkey_authentication);
+	M_CP_STROPT(pubkey_agent);
+	M_CP_STROPT(pubkey_agent_runas);
 	M_CP_INTOPT(kerberos_authentication);
 	M_CP_INTOPT(hostbased_authentication);
 	M_CP_INTOPT(kbd_interactive_authentication);
@@ -1666,6 +1692,10 @@ dump_config(ServerOptions *o)
 	dump_cfg_string(sAuthorizedKeysFile2, o->authorized_keys_file2);
 	dump_cfg_string(sForceCommand, o->adm_forced_command);
 	dump_cfg_string(sChrootDirectory, o->chroot_directory);
+#ifdef WITH_PUBKEY_AGENT
+	dump_cfg_string(sPubkeyAgent, o->pubkey_agent);
+	dump_cfg_string(sPubkeyAgentRunAs, o->pubkey_agent_runas);
+#endif
 
 	/* string arguments requiring a lookup */
 	dump_cfg_string(sLogLevel, log_level_name(o->log_level));
diff -up openssh-5.4p1/servconf.h.pka openssh-5.4p1/servconf.h
--- openssh-5.4p1/servconf.h.pka	2010-03-01 18:10:46.000000000 +0100
+++ openssh-5.4p1/servconf.h	2010-03-01 18:10:50.000000000 +0100
@@ -155,6 +155,8 @@ typedef struct {
 	int	num_permitted_opens;
 
 	char   *chroot_directory;
+	char   *pubkey_agent;
+	char   *pubkey_agent_runas;
 }       ServerOptions;
 
 void	 initialize_server_options(ServerOptions *);
diff -up openssh-5.4p1/sshd_config.0.pka openssh-5.4p1/sshd_config.0
--- openssh-5.4p1/sshd_config.0.pka	2010-03-01 18:10:46.000000000 +0100
+++ openssh-5.4p1/sshd_config.0	2010-03-01 18:10:50.000000000 +0100
@@ -352,7 +352,8 @@ DESCRIPTION
              KbdInteractiveAuthentication, KerberosAuthentication,
              MaxAuthTries, MaxSessions, PasswordAuthentication,
              PermitEmptyPasswords, PermitOpen, PermitRootLogin,
-             PubkeyAuthentication, RhostsRSAAuthentication, RSAAuthentication,
+             PubkeyAuthentication, PubkeyAgent, PubkeyAgentRunAs,
+             RhostsRSAAuthentication, RSAAuthentication,
              X11DisplayOffset, X11Forwarding and X11UseLocalHost.
 
      MaxAuthTries
@@ -461,6 +462,17 @@ DESCRIPTION
              fault is ``yes''.  Note that this option applies to protocol ver-
              sion 2 only.
 
+     PubkeyAgent
+             Specifies which agent is used for lookup of the user's public
+             keys. Empty string means to use the authorized_keys file.  By
+             default there is no PubkeyAgent set.  Note that this option has
+             an effect only with PubkeyAuthentication switched on.
+
+     PubkeyAgentRunAs
+             Specifies the user under whose account the PubkeyAgent is run.
+             Empty string (the default value) means the user being authorized
+             is used.
+
      RhostsRSAAuthentication
              Specifies whether rhosts or /etc/hosts.equiv authentication to-
              gether with successful RSA host authentication is allowed.  The
diff -up openssh-5.4p1/sshd_config.5.pka openssh-5.4p1/sshd_config.5
--- openssh-5.4p1/sshd_config.5.pka	2010-03-01 18:10:46.000000000 +0100
+++ openssh-5.4p1/sshd_config.5	2010-03-01 18:10:50.000000000 +0100
@@ -618,6 +618,9 @@ Available keywords are
 .Cm KerberosAuthentication ,
 .Cm MaxAuthTries ,
 .Cm MaxSessions ,
+.Cm PubkeyAuthentication ,
+.Cm PubkeyAgent ,
+.Cm PubkeyAgentRunAs ,
 .Cm PasswordAuthentication ,
 .Cm PermitEmptyPasswords ,
 .Cm PermitOpen ,
@@ -814,6 +817,16 @@ Specifies whether public key authenticat
 The default is
 .Dq yes .
 Note that this option applies to protocol version 2 only.
+.It Cm PubkeyAgent
+Specifies which agent is used for lookup of the user's public
+keys. Empty string means to use the authorized_keys file.
+By default there is no PubkeyAgent set.
+Note that this option has an effect only with PubkeyAuthentication
+switched on.
+.It Cm PubkeyAgentRunAs
+Specifies the user under whose account the PubkeyAgent is run. Empty
+string (the default value) means the user being authorized is used.
+.Dq 
 .It Cm RhostsRSAAuthentication
 Specifies whether rhosts or /etc/hosts.equiv authentication together
 with successful RSA host authentication is allowed.
diff -up openssh-5.4p1/sshd_config.pka openssh-5.4p1/sshd_config
--- openssh-5.4p1/sshd_config.pka	2010-03-01 18:10:46.000000000 +0100
+++ openssh-5.4p1/sshd_config	2010-03-01 18:10:50.000000000 +0100
@@ -45,6 +45,8 @@ SyslogFacility AUTHPRIV
 #RSAAuthentication yes
 #PubkeyAuthentication yes
 #AuthorizedKeysFile	.ssh/authorized_keys
+#PubkeyAgent none
+#PubkeyAgentRunAs nobody
 
 # For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
 #RhostsRSAAuthentication no