From f7978982d31f67867d8200f9f3102eb423312abc Mon Sep 17 00:00:00 2001
From: Alan Coopersmith <[email protected]>
Date: Tue, 29 Dec 2015 12:50:16 -0800
Subject: [PATCH 04/19] sdtlogin

Adds SDTLOGIN interface, which drops the Xserver to user
perms rather than running as root, for added security on Solaris.
Original date:2008-05-06 owner:yippi type:feature

For the original definition, see Sun ASARC case 1995/390.
For the current implementation in the X server, see sun-src/os/dtlogin.c
and dtlogin-userinfo.patch in open-src/xserver/xorg in the X gate.
---
 common/gdm-common.h         |   5 ++
 daemon/gdm-server.c         |  11 +++++
 daemon/gdm-session-worker.c | 116 ++++++++++++++++++++++++++++++++++++++++++++
 daemon/main.c               |  15 ++++++
 4 files changed, 147 insertions(+)

diff --git a/common/gdm-common.h b/common/gdm-common.h
index 19dbbbb..6ac61c0 100644
--- a/common/gdm-common.h
+++ b/common/gdm-common.h
@@ -42,6 +42,11 @@ GQuark gdm_common_error_quark (void);
 typedef char * (*GdmExpandVarFunc) (const char *var,
                                     gpointer user_data);
 
+#ifdef __sun
+#define GDM_DT_DIR "/var/dt"
+#define GDM_SDTLOGIN_DIR "/var/dt/sdtlogin"
+#endif
+
 G_BEGIN_DECLS
 
 int            gdm_wait_on_pid           (int pid);
diff --git a/daemon/gdm-server.c b/daemon/gdm-server.c
index 08f2354..2cec263 100644
--- a/daemon/gdm-server.c
+++ b/daemon/gdm-server.c
@@ -742,6 +742,17 @@ gdm_server_spawn (GdmServer    *server,
                 goto out;
         }
 
+#if __sun
+        /* Remove old communication pipe, if present */
+        char *display_num = strchr(server->priv->display_name, ':');
+        if (display_num != NULL && display_num[1] != '\0') {
+                char *old_pipe = g_strdup_printf ("%s/%s", GDM_SDTLOGIN_DIR,
+                                                  display_num + 1);
+                VE_IGNORE_EINTR (g_remove (old_pipe));
+                g_free (old_pipe);
+        }
+#endif
+
         env = get_server_environment (server);
 
         freeme = g_strjoinv (" ", argv);
diff --git a/daemon/gdm-session-worker.c b/daemon/gdm-session-worker.c
index 291caad..93c9e82 100644
--- a/daemon/gdm-session-worker.c
+++ b/daemon/gdm-session-worker.c
@@ -38,6 +38,7 @@
 #include <pwd.h>
 
 #if __sun
+#include <sys/param.h>
 #define GDM_PAM_QUAL
 #else
 #define GDM_PAM_QUAL const
@@ -2044,6 +2045,115 @@ out:
         return fd;
 }
 
+#ifdef __sun
+static void
+solaris_xserver_cred (const char *username, struct passwd *passwd_entry,
+                      const char *x11_display_name)
+{
+        FILE *fp;
+        struct stat statbuf;
+        gid_t  groups[NGROUPS_UMAX];
+        char *tmp, *p, pipe[MAXPATHLEN], info[MAXPATHLEN];
+        int display_number = 0;
+        int fd, i;
+        int ngroups;
+
+        if (g_access (passwd_entry->pw_dir, F_OK) != 0) {
+                g_debug ("solaris_xserver_cred: no HOME dir access\n");
+                return;
+        }
+
+        /*
+         * Handshake with server. Make sure it created a pipe.
+         * Open and write.
+         */
+        if ((tmp = strstr (x11_display_name, ":")) != NULL) {
+                tmp++;
+                display_number = g_ascii_strtod (tmp, &p);
+
+                if (errno != 0) {
+                        g_debug ("solaris_xserver_cred: problem getting display number\n");
+                        return;
+                }
+        }
+
+        if (g_stat (GDM_SDTLOGIN_DIR, &statbuf) == 0) {
+                if (! S_ISDIR(statbuf.st_mode)) {
+                        g_debug ("solaris_xserver_cred: %s is not a directory\n",
+                                 GDM_SDTLOGIN_DIR);
+                        return;
+                }
+        } else {
+                g_debug ("solaris_xserver_cred: %s does not exist\n", GDM_SDTLOGIN_DIR);
+                return;
+        }
+
+        snprintf (pipe, sizeof(pipe), "%s/%d", GDM_SDTLOGIN_DIR, display_number);
+        fd = open (pipe, O_RDWR);
+        g_remove (pipe);
+
+        if (fd < 0) {
+                g_debug ("solaris_xserver_cred: could not open %s\n", pipe);
+                return;
+        }
+        if (fstat (fd, &statbuf) == 0 ) {
+                if (! S_ISFIFO(statbuf.st_mode)) {
+                        close (fd);
+                        g_debug ("solaris_xserver_cred: %s is not a pipe\n", pipe);
+                        return;
+                }
+        } else {
+                close (fd);
+                g_debug ("solaris_xserver_cred: %s does not exist\n", pipe);
+                return;
+        }
+        fp = fdopen (fd, "w");
+        if (fp == NULL) {
+                close (fd);
+                g_debug ("solaris_xserver_cred: could not fdopen %s\n", pipe);
+                return;
+        }
+
+        snprintf (info, sizeof(info), "GID=\"%d\"; ", passwd_entry->pw_gid);
+        fputs (info, fp);
+        g_debug ("solaris_xserver_cred: %s\n", info);
+
+        if (initgroups (username, passwd_entry->pw_gid) == -1) {
+                ngroups = 0;
+        } else {
+                ngroups = getgroups (NGROUPS_UMAX, groups);
+        }
+
+        for (i=0; i < ngroups; i++) {
+                snprintf (info, sizeof(info), "G_LIST_ID=\"%u\" ", groups[i]);
+                fputs (info, fp);
+                g_debug ("solaris_xserver_cred: %s\n", info);
+        }
+
+        if (ngroups > 0) {
+                fputc (';', fp);
+        }
+
+        snprintf (info, sizeof(info), " HOME=\"%s\" ", passwd_entry->pw_dir);
+        fputs (info, fp);
+        g_debug ("solaris_xserver_cred: %s\n", info);
+
+        snprintf (info, sizeof(info), " UID=\"%d\" EOF=\"\";", passwd_entry->pw_uid);
+        fputs (info, fp);
+        g_debug ("solaris_xserver_cred: %s\n", info);
+
+        /*
+         * Handshake with server. Make sure it read the pipe.
+         *
+         * Close file descriptor.
+         */
+        fflush (fp);
+        fclose (fp);
+
+        return;
+}
+#endif
+
 static gboolean
 gdm_session_worker_start_session (GdmSessionWorker  *worker,
                                   GError           **error)
@@ -2061,6 +2171,12 @@ gdm_session_worker_start_session (GdmSessionWorker  *worker,
                          worker->priv->arguments[0]);
         }
 
+#ifdef __sun
+        solaris_xserver_cred (worker->priv->username,
+                              passwd_entry,
+                              worker->priv->x11_display_name);
+#endif
+
         error_code = PAM_SUCCESS;
 
 #ifdef WITH_SYSTEMD
diff --git a/daemon/main.c b/daemon/main.c
index ca2dda3..50f6e94 100644
--- a/daemon/main.c
+++ b/daemon/main.c
@@ -324,6 +324,21 @@ main (int    argc,
 
         block_sigusr1 ();
 
+#ifdef __sun
+        {
+                struct stat statbuf;
+                int r;
+
+                r = stat (GDM_DT_DIR, &statbuf);
+                if (r < 0) {
+                        g_mkdir (GDM_DT_DIR, 0755);
+                }
+
+                g_remove (GDM_SDTLOGIN_DIR);
+                g_mkdir (GDM_SDTLOGIN_DIR, 0700);
+        }
+#endif
+
         bindtextdomain (GETTEXT_PACKAGE, GNOMELOCALEDIR);
         textdomain (GETTEXT_PACKAGE);
         setlocale (LC_ALL, "");
-- 
2.7.4