security: Exit on failure of env_set_user()

CVE-2026-32107. Prevent possible privilege escalation if setuid()
fails.

sesman/sesexec/env.c

@@ -40,7 +40,7 @@
 #include "xrdp_sockets.h"
 
 /******************************************************************************/
-int
+void
 env_set_user(int uid,
              const struct list *env_names, const struct list *env_values)
 {
@@ -58,32 +58,40 @@ env_set_user(int uid,
     error = g_getuser_info_by_uid(uid, &pw_username, &pw_gid, &pw_shell,
                                   &pw_dir, 0);
 
-    if (error == 0)
+    if (error != 0)
     {
+        LOG(LOG_LEVEL_ALWAYS,
+            "fatal error getting user info for uid %d: %s", uid,
+            g_get_strerror());
+        goto fatal;
+    }
     g_rm_temp_dir();
     g_clearenv();
 #ifdef HAVE_SETUSERCONTEXT
-        error = g_set_allusercontext(uid);
+    if (g_set_allusercontext(uid) != 0)
+    {
+        LOG(LOG_LEVEL_ALWAYS,
+            "fatal error setting allusercontext for uid %d: %s",
+            uid, g_get_strerror());
+        goto fatal;
+    }
 #else
     /* Set some of the things setusercontext() handles on other
      * systems */
 
-        /* Primary group. Note that secondary groups should already
+    /* GID/UID. Note that secondary groups should already
      * have been set, if we're not using setusercontext() */
-        error = g_setgid(pw_gid);
-
-        if (error == 0)
+    if (g_setgid(pw_gid) != 0 || g_setuid(uid) != 0)
     {
-            error = g_setuid(uid);
+        LOG(LOG_LEVEL_ALWAYS,
+            "fatal error getting setting uid:gid to %d:%d - %s",
+            uid, pw_gid, g_get_strerror());
+        goto fatal;
     }
 
-        if (error == 0)
-        {
     g_setenv_log("PATH", "/sbin:/bin:/usr/bin:/usr/local/bin", 1);
-        }
 #endif
-        if (error == 0)
-        {
+
     g_setenv_log("SHELL", pw_shell, 1);
     g_setenv_log("USER", pw_username, 1);
     g_setenv_log("LOGNAME", pw_username, 1);
@@ -131,17 +139,17 @@ env_set_user(int uid,
             g_setenv_log("XAUTHORITY", text, 1);
         }
     }
-        }
-    }
-    else
-    {
-        LOG(LOG_LEVEL_ERROR,
-            "error getting user info for uid %d", uid);
-    }
 
     g_free(pw_username);
     g_free(pw_dir);
     g_free(pw_shell);
 
-    return error;
+    return;
+
+fatal:
+    g_free(pw_username);
+    g_free(pw_dir);
+    g_free(pw_shell);
+
+    g_exit(1);
 }

sesman/sesexec/env.h

@@ -46,10 +46,12 @@ env_check_password_file(const char *filename, const char *password);
  * @param uid user ID
  * @param env_names List of session environment variables to set
  * @param env_values List of session environment values to set
- * @return 0 on success, g_getuser_info() error codes on error
+ *
+ * On error, the calling process exits, to prevent privilege
+ * escalations.
  *
  */
-int
+void
 env_set_user(int uid,
              const struct list *env_names, const struct list *env_values);