add a connector library and (reluctantly) a PAM module

Here are some patches to add one library and one PAM module so other
programs (apart from gdm) can easily interact with ConsoleKit. It's
mainly going to be used, I think, by login(1) and xinit(1). I'm not
super happy about doing a PAM module but the Fedora util-linux package
maintainer seems to be insist on this instead of just patching login(1).
The PAM module isn't built by default. Both pieces of code are licensed
under the MIT license as god knows what might want to use them. Sounds
good to you?

3 files changed, 325 insertions, 0 deletions

diff --git a/pam-ck-connector/Makefile.am b/pam-ck-connector/Makefile.am
new file mode 100644
index 0000000..e03923b
--- /dev/null
+++ b/pam-ck-connector/Makefile.am
@@ -0,0 +1,17 @@
+
+if ENABLE_PAM_MODULE
+
+INCLUDES = $(LIBDBUS_CFLAGS) -I$(top_builddir)/libck-connector
+
+pamlib_LTLIBRARIES=pam_ck_connector.la
+pamlibdir=/lib/security
+pam_ck_connector_la_SOURCES = pam-ck-connector.c
+pam_ck_connector_la_LDFLAGS = -no-undefined -module -avoid-version
+pam_ck_connector_la_LIBADD =  -lpam $(LIBDBUS_LIBS) $(top_builddir)/libck-connector/libck-connector.la
+
+man_MANS = pam_ck_connector.8
+
+endif
+
+clean-local :
+	rm -f *~
diff --git a/pam-ck-connector/pam-ck-connector.c b/pam-ck-connector/pam-ck-connector.c
new file mode 100644
index 0000000..835be0c
--- /dev/null
+++ b/pam-ck-connector/pam-ck-connector.c
@@ -0,0 +1,228 @@
+/*
+ * pam-ck-connector.c : PAM module for registering with CK
+ *
+ * Copyright (c) 2007 David Zeuthen <davidz@redhat.com>
+ * 
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ * 
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <ctype.h>
+#include <pwd.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <errno.h>
+
+#define PAM_SM_SESSION
+
+#include <security/pam_modules.h>
+#include <security/_pam_macros.h>
+#include <security/pam_modutil.h>
+#include <security/pam_ext.h>
+
+#include "ck-connector.h"
+
+static int opt_debug = FALSE;
+
+static void
+_parse_pam_args (const pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	int i;
+
+	opt_debug = FALSE;
+	for (i = 0; i < argc && argv[i] != NULL; i++) {
+		if (strcmp (argv[i] ,"debug") == 0) {
+			opt_debug = TRUE;
+		} else {
+			pam_syslog (pamh, LOG_ERR, "unknown option: %s", argv[i]);
+		}
+	}
+}
+
+
+PAM_EXTERN int
+pam_sm_authenticate (pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	return PAM_IGNORE;
+}
+
+PAM_EXTERN int 
+pam_sm_setcred (pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	return PAM_IGNORE;
+}
+
+static uid_t
+_util_name_to_uid (const char *username, gid_t *default_gid)
+{
+        int rc;
+        uid_t res;
+        char *buf = NULL;
+        unsigned int bufsize;
+        struct passwd pwd;
+        struct passwd *pwdp;
+
+        res = (uid_t) -1;
+
+        bufsize = sysconf (_SC_GETPW_R_SIZE_MAX);
+        buf = calloc (sizeof (char), bufsize);
+        rc = getpwnam_r (username, &pwd, buf, bufsize, &pwdp);
+        if (rc != 0 || pwdp == NULL) {
+                goto out;
+        }
+
+        res = pwdp->pw_uid;
+        if (default_gid != NULL)
+                *default_gid = pwdp->pw_gid;
+
+out:
+        free (buf);
+        return res;
+}
+
+/* our singleton */
+static CKConnector *ckc = NULL;
+
+PAM_EXTERN int 
+pam_sm_close_session (pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	if (ckc != NULL) {
+		ckc_free (ckc);
+		ckc = NULL;
+	}
+	return PAM_SUCCESS;
+}
+
+PAM_EXTERN int 
+pam_sm_open_session (pam_handle_t *pamh, int flags, int argc, const char **argv)
+{
+	int ret;
+	const char *user;
+	const char *tty;
+	const char *x11_display;
+	const char *s;
+	uid_t uid;
+	char buf[256];
+
+	ret = PAM_IGNORE;
+
+	_parse_pam_args (pamh, flags, argc, argv);
+
+	/* Register with ConsoleKit as part of the session management */
+	if (ckc != NULL) {
+		pam_syslog (pamh, LOG_ERR, "process already registered with ConsoleKit");
+		goto out;
+	}
+
+	ckc = ckc_new ();
+	if (ckc == NULL) {
+		pam_syslog (pamh, LOG_ERR, "oom creating ConsoleKit connector object");
+		goto out;
+	}
+
+	if (pam_get_user (pamh, &user, NULL) != PAM_SUCCESS || user == NULL) {
+		pam_syslog (pamh, LOG_ERR, "cannot determine username");
+		goto out;
+	}
+
+	if (pam_get_item (pamh, PAM_TTY, (const void **) &tty) != PAM_SUCCESS || tty == NULL) {
+		pam_syslog (pamh, LOG_ERR, "cannot determine tty");
+		goto out;
+	}
+
+	if ((s = pam_getenv (pamh, "CKCON_TTY")) != NULL) {
+		tty = s;
+		if (opt_debug)
+			pam_syslog (pamh, LOG_INFO, "using '%s' as tty (from CKCON_TTY)", tty);
+	}
+
+	x11_display = NULL;
+	if ((s = pam_getenv (pamh, "CKCON_X11_DISPLAY")) != NULL) {
+		x11_display = s;
+		if (opt_debug)
+			pam_syslog (pamh, LOG_INFO, "using '%s' as X11 display (from CKCON_X11_DISPLAY)", x11_display);
+	}
+
+	uid = _util_name_to_uid (user, NULL);
+	if (uid == (uid_t) -1) {
+		pam_syslog (pamh, LOG_ERR, "cannot determine uid for user '%s'", user);
+		goto out;
+	}
+
+	if (!ckc_create_local_session (ckc, uid, tty, x11_display)) {
+		/* this might not be a bug for servers that don't have
+		 * the message bus or ConsoleKit daemon running - so
+		 * only log a message in debugging mode.
+		 */
+		if (opt_debug)
+			pam_syslog (pamh, LOG_DEBUG, "insufficient privileges or D-Bus / ConsoleKit not available");
+		goto out;
+	}
+
+	/* now set the cookie */
+	buf[sizeof (buf) - 1] = '\0';
+	snprintf (buf, sizeof (buf) - 1, "XDG_SESSION_COOKIE=%s", ckc_get_cookie (ckc));
+	if (pam_putenv (pamh, buf) != PAM_SUCCESS) {
+		pam_syslog (pamh, LOG_ERR, "unable to set XDG_SESSION_COOKIE vairable");
+		/* tear down session the hard way */
+		ckc_free (ckc);
+		ckc = NULL;
+		goto out;
+	}
+		    
+	if (opt_debug) {
+		pam_syslog (pamh, LOG_DEBUG, "registered uid=%d on tty='%s' with ConsoleKit", uid, tty);
+	}
+
+	/* note that we're leaking our CKConnector instance ckc - this
+	 * is *by design* such that when the login manager (that uses
+	 * us) exits / crashes / etc. ConsoleKit will notice, via D-Bus
+	 * connection tracking, that the login session ended.
+	 */
+
+	ret = PAM_SUCCESS;
+
+out:
+	return ret;
+}
+
+#ifdef PAM_STATIC
+
+struct pam_module _pam_ckconnector_modstruct = {
+	"pam_ck_connector",
+	pam_sm_authenticate,
+	pam_sm_setcred,
+	NULL,
+	pam_sm_open_session,
+	pam_sm_close_session,
+	NULL,
+};
+
+#endif
+
+/* end of module definition */
diff --git a/pam-ck-connector/pam_ck_connector.8 b/pam-ck-connector/pam_ck_connector.8
new file mode 100644
index 0000000..43241a0
--- /dev/null
+++ b/pam-ck-connector/pam_ck_connector.8
@@ -0,0 +1,80 @@
+.\"     Title: pam_ck_connector
+.\"    Author: David Zeuthen <davidz@redhat.com>
+.\"      Date: 02/27/2007
+.\"
+.TH "PAM_CK_CONNECTOR" "8" "02/27/2007" "ConsoleKit Manual" "ConsoleKit Manual"
+.\" disable hyphenation
+.nh
+.\" disable justification (adjust text to left margin only)
+.ad l
+.SH "NAME"
+pam_ck_connector \- Register sessin with ConsoleKit
+.SH "SYNOPSIS"
+.HP 12
+\fBpam_ck_connector.so\fR [debug]
+.SH "DESCRIPTION"
+.PP
+The pam_ck_connector PAM module registers a login session with
+the system-wide 
+.I ConsoleKit 
+daemon. This PAM module should be used with
+caution; only local login managers such as 
+.B login(1)
+should use this. Since the 
+.I ConsoleKit
+daemon can accept both an
+.B tty
+and an X11 display the normal parameters set by PAM are not always
+useful. 
+
+An application can therefore override these with the PAM environment
+variables
+.B CKCON_TTY
+and
+.B CHCON_X11_DISPLAY
+(the application should remember to unset these before starting the
+login session). 
+
+Also note that the
+.I ConsoleKit
+daemon may reject registration attempts if the given set of data are
+inconsistent with each other. More more information, see the
+.I ConsoleKit
+documentation on the
+.B OpenSessionWithParameters()
+method call on the
+.B org.freedesktop.ConsoleKit.Manager
+D-Bus interface.
+
+If registration with the
+.I ConsoleKit
+daemon succeeds, this PAM module will set the environment variable
+.B XDG_SESSION_COOKIE
+which is used to defined membership of a login session.
+
+This PAM module has the side effect that it creates a connection to
+the system message bus that is kept open until the session ends. This
+is used by the 
+.I ConsoleKit
+daemon to track the life-cycle of the
+session and, as such, should the login manager crash, the session will
+be properly unregistered.
+
+.SH "OPTIONS"
+.PP
+.TP 3n
+\fBdebug\fR
+Print debug information.
+.fi
+.RE
+.sp
+.SH "SEE ALSO"
+.PP
+
+\fBpam.conf\fR(5),
+\fBpam.d\fR(8),
+\fBpam\fR(8),
+\fBdbus-daemon\fR(1)
+.SH "AUTHOR"
+.PP
+pam_ck_connector was written by David Zeuthen <davidz@redhat.com>.