From 4ae930d9ddb8d2f806f89068142f4e7cd4df85e6 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Tue, 26 Nov 2013 05:05:00 +0100

Subject: [PATCH] pam_systemd: do not set XDG_RUNTIME_DIR if the session's

 original user is not the same as the newly logged in one

It's better not to set any XDG_RUNTIME_DIR at all rather than one of a

different user. So let's do this.

This changes the bus call parameters of CreateSession(), but that is

explicitly an internal API hence should be fine. Note however, that a

logind restart (the way the RPM postinst scriptlets do it) is necessary

to make things work again.

(cherry picked from commit baae0358f349870544884e405e82e4be7d8add9f)

Conflicts:

	src/login/logind-dbus.c

	src/login/logind-session-dbus.c

	src/login/pam-module.c

Note: Backported by Dr. Werner Fink <werner@suse.de>

---

 src/login/logind-dbus.c         |  1 +

 src/login/logind-session-dbus.c |  1 +

 src/login/pam-module.c          | 67 ++++++++++++++++++++++-------------------

 3 files changed, 38 insertions(+), 31 deletions(-)

diff --git a/src/login/logind-dbus.c b/src/login/logind-dbus.c

index 583d62e..6f3e442 100644

--- a/src/login/logind-dbus.c

+++ b/src/login/logind-dbus.c

@@ -523,6 +523,7 @@ static int bus_manager_create_session(Manager *m, DBusMessage *message) {

                                 DBUS_TYPE_OBJECT_PATH, &path,

                                 DBUS_TYPE_STRING, &session->user->runtime_path,

                                 DBUS_TYPE_UNIX_FD, &fifo_fd,

+                                DBUS_TYPE_UINT32, &session->user->uid,

                                 DBUS_TYPE_STRING, &cseat,

                                 DBUS_TYPE_UINT32, &vtnr,

                                 DBUS_TYPE_BOOLEAN, &exists,

diff --git a/src/login/logind-session-dbus.c b/src/login/logind-session-dbus.c

index be4e01c..86b0746 100644

--- a/src/login/logind-session-dbus.c

+++ b/src/login/logind-session-dbus.c

@@ -755,6 +755,7 @@ int session_send_create_reply(Session *s, DBusError *error) {

                                     DBUS_TYPE_OBJECT_PATH, &path,

                                     DBUS_TYPE_STRING, &s->user->runtime_path,

                                     DBUS_TYPE_UNIX_FD, &fifo_fd,

+                                    DBUS_TYPE_UINT32, &s->user->uid,

                                     DBUS_TYPE_STRING, &cseat,

                                     DBUS_TYPE_UINT32, &vtnr,

                                     DBUS_TYPE_BOOLEAN, &exists,

diff --git a/src/login/pam-module.c b/src/login/pam-module.c

index aa09ec1..4d6b052 100644

--- a/src/login/pam-module.c

+++ b/src/login/pam-module.c

@@ -86,31 +86,24 @@ static int get_user_data(

         const char *username = NULL;

         struct passwd *pw = NULL;

-        uid_t uid;

         int r;

         assert(handle);

         assert(ret_username);

         assert(ret_pw);

-        r = audit_loginuid_from_pid(0, &uid);

-        if (r >= 0)

-                pw = pam_modutil_getpwuid(handle, uid);

-        else {

-                r = pam_get_user(handle, &username, NULL);

-                if (r != PAM_SUCCESS) {

-                        pam_syslog(handle, LOG_ERR, "Failed to get user name.");

-                        return r;

-                }

-

-                if (isempty(username)) {

-                        pam_syslog(handle, LOG_ERR, "User name not valid.");

-                        return PAM_AUTH_ERR;

-                }

+        r = pam_get_user(handle, &username, NULL);

+        if (r != PAM_SUCCESS) {

+                pam_syslog(handle, LOG_ERR, "Failed to get user name.");

+                return r;

+        }

-                pw = pam_modutil_getpwnam(handle, username);

+        if (isempty(username)) {

+                pam_syslog(handle, LOG_ERR, "User name not valid.");

+                return PAM_AUTH_ERR;

         }

+        pw = pam_modutil_getpwnam(handle, username);

         if (!pw) {

                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");

                 return PAM_USER_UNKNOWN;

@@ -123,16 +116,14 @@ static int get_user_data(

 }

 static int get_seat_from_display(const char *display, const char **seat, uint32_t *vtnr) {

-        _cleanup_free_ char *p = NULL;

-        int r;

-        _cleanup_close_ int fd = -1;

         union sockaddr_union sa = {

                 .un.sun_family = AF_UNIX,

         };

+         _cleanup_free_ char *p = NULL, *tty = NULL;

+         _cleanup_close_ int fd = -1;

         struct ucred ucred;

         socklen_t l;

-        _cleanup_free_ char *tty = NULL;

-        int v;

+        int v, r;

         assert(display);

         assert(vtnr);

@@ -194,14 +185,12 @@ _public_ PAM_EXTERN int pam_sm_open_session(

         dbus_bool_t remote, existing;

         int r;

         uint32_t vtnr = 0;

+        uid_t original_uid;

         assert(handle);

         dbus_error_init(&error);

-        if (debug)

-                pam_syslog(handle, LOG_INFO, "pam-systemd initializing");

-

         /* Make this a NOP on non-logind systems */

         if (!logind_running())

                 return PAM_SUCCESS;

@@ -214,6 +203,9 @@ _public_ PAM_EXTERN int pam_sm_open_session(

                 goto finish;

         }

+        if (debug)

+                pam_syslog(handle, LOG_INFO, "pam-systemd initializing");

+

         r = get_user_data(handle, &username, &pw;;

         if (r != PAM_SUCCESS)

                 goto finish;

@@ -381,7 +373,11 @@ _public_ PAM_EXTERN int pam_sm_open_session(

         if (debug)

                 pam_syslog(handle, LOG_DEBUG, "Asking logind to create session: "

                            "uid=%u pid=%u service=%s type=%s class=%s seat=%s vtnr=%u tty=%s display=%s remote=%s remote_user=%s remote_host=%s",

-                           uid, pid, service, type, class, seat, vtnr, tty, display, yes_no(remote), remote_user, remote_host);

+                              pw->pw_uid, pid,

+                              strempty(service),

+                              type, class,

+                              seat, vtnr, tty, display,

+                              yes_no(remote), remote_user, remote_host);

         reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error);

         if (!reply) {

@@ -395,6 +391,7 @@ _public_ PAM_EXTERN int pam_sm_open_session(

                                    DBUS_TYPE_OBJECT_PATH, &object_path,

                                    DBUS_TYPE_STRING, &runtime_path,

                                    DBUS_TYPE_UNIX_FD, &session_fd,

+                                   DBUS_TYPE_UINT32, &original_uid,

                                    DBUS_TYPE_STRING, &seat,

                                    DBUS_TYPE_UINT32, &vtnr,

                                    DBUS_TYPE_BOOLEAN, &existing,

@@ -406,8 +403,8 @@ _public_ PAM_EXTERN int pam_sm_open_session(

         if (debug)

                 pam_syslog(handle, LOG_DEBUG, "Reply from logind: "

-                           "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u",

-                           id, object_path, runtime_path, session_fd, seat, vtnr);

+                           "id=%s object_path=%s runtime_path=%s session_fd=%d seat=%s vtnr=%u original_uid=%u",

+                           id, object_path, runtime_path, session_fd, seat, vtnr, original_uid);

         r = pam_misc_setenv(handle, "XDG_SESSION_ID", id, 0);

         if (r != PAM_SUCCESS) {

@@ -415,10 +412,18 @@ _public_ PAM_EXTERN int pam_sm_open_session(

                 goto finish;

         }

-        r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0);

-        if (r != PAM_SUCCESS) {

-                pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");

-                goto finish;

+        if (original_uid == pw->pw_uid) {

+                /* Don't set $XDG_RUNTIME_DIR if the user we now

+                 * authenticated for does not match the original user

+                 * of the session. We do this in order not to result

+                 * in privileged apps clobbering the runtime directory

+                 * unnecessarily. */

+

+                r = pam_misc_setenv(handle, "XDG_RUNTIME_DIR", runtime_path, 0);

+                if (r != PAM_SUCCESS) {

+                         pam_syslog(handle, LOG_ERR, "Failed to set runtime dir.");

+                         goto finish;

+                }

         }

         if (!isempty(seat)) {