From a7424cc002af7c379f5cb1292c69176febe8ff7f Mon Sep 17 00:00:00 2001
From: "Todd C. Miller" <Todd.Miller@courtesan.com>
Date: Thu, 9 Aug 2012 14:11:41 -0400
Subject: [PATCH] If sudo.conf contains an I/O plugin but no policy plugin, use
 sudoers for the policy plugin.  If a policy plugin is specified without an
 I/O plugin, only the policy plugin will be loaded.

---
 common/sudo_conf.c |  22 +----
 src/load_plugins.c | 196 ++++++++++++++++++++++++++++-----------------
 2 files changed, 122 insertions(+), 96 deletions(-)

diff --git a/common/sudo_conf.c b/common/sudo_conf.c
index 238d21f26..144bbc3b6 100644
--- a/common/sudo_conf.c
+++ b/common/sudo_conf.c
@@ -292,7 +292,6 @@ void
 sudo_conf_read(void)
 {
     struct sudo_conf_table *cur;
-    struct plugin_info *info;
     struct stat sb;
     FILE *fp;
     char *cp;
@@ -346,25 +345,6 @@ sudo_conf_read(void)
 	}
     }
     fclose(fp);
-
 done:
-    if (tq_empty(&sudo_conf_data.plugins)) {
-	/* Default policy plugin */
-	info = ecalloc(1, sizeof(*info));
-	info->symbol_name = "sudoers_policy";
-	info->path = SUDOERS_PLUGIN;
-	/* info->options = NULL; */
-	info->prev = info;
-	/* info->next = NULL; */
-	tq_append(&sudo_conf_data.plugins, info);
-
-	/* Default I/O plugin */
-	info = ecalloc(1, sizeof(*info));
-	info->symbol_name = "sudoers_io";
-	info->path = SUDOERS_PLUGIN;
-	/* info->options = NULL; */
-	info->prev = info;
-	/* info->next = NULL; */
-	tq_append(&sudo_conf_data.plugins, info);
-    }
+    return;
 }
diff --git a/src/load_plugins.c b/src/load_plugins.c
index 767f8ee70..0371e9f50 100644
--- a/src/load_plugins.c
+++ b/src/load_plugins.c
@@ -55,103 +55,151 @@
 #endif
 
 /*
- * Load the plugins listed in sudo.conf.
+ * Load the plugin specified by "info".
  */
-bool
-sudo_load_plugins(struct plugin_container *policy_plugin,
-    struct plugin_container_list *io_plugins)
+static bool
+sudo_load_plugin(struct plugin_container *policy_plugin,
+    struct plugin_container_list *io_plugins, struct plugin_info *info)
 {
-    struct plugin_info_list *plugins;
-    struct generic_plugin *plugin;
     struct plugin_container *container;
-    struct plugin_info *info;
+    struct generic_plugin *plugin;
     struct stat sb;
     void *handle;
     char path[PATH_MAX];
     bool rval = false;
-    debug_decl(sudo_load_plugins, SUDO_DEBUG_PLUGIN)
+    debug_decl(sudo_load_plugin, SUDO_DEBUG_PLUGIN)
 
-    /* Walk plugin list. */
-    plugins = sudo_conf_plugins();
-    tq_foreach_fwd(plugins, info) {
-	if (info->path[0] == '/') {
-	    if (strlcpy(path, info->path, sizeof(path)) >= sizeof(path)) {
-		warningx(_("%s: %s"), info->path, strerror(ENAMETOOLONG));
-		goto done;
-	    }
-	} else {
-	    if (snprintf(path, sizeof(path), "%s%s", _PATH_SUDO_PLUGIN_DIR,
-		info->path) >= sizeof(path)) {
-		warningx(_("%s%s: %s"), _PATH_SUDO_PLUGIN_DIR, info->path,
-		    strerror(ENAMETOOLONG));
-		goto done;
-	    }
-	}
-	if (stat(path, &sb) != 0) {
-	    warning("%s", path);
-	    goto done;
-	}
-	if (sb.st_uid != ROOT_UID) {
-	    warningx(_("%s must be owned by uid %d"), path, ROOT_UID);
+    if (info->path[0] == '/') {
+	if (strlcpy(path, info->path, sizeof(path)) >= sizeof(path)) {
+	    warningx(_("%s: %s"), info->path, strerror(ENAMETOOLONG));
 	    goto done;
 	}
-	if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
-	    warningx(_("%s must be only be writable by owner"), path);
+    } else {
+	if (snprintf(path, sizeof(path), "%s%s", _PATH_SUDO_PLUGIN_DIR,
+	    info->path) >= sizeof(path)) {
+	    warningx(_("%s%s: %s"), _PATH_SUDO_PLUGIN_DIR, info->path,
+		strerror(ENAMETOOLONG));
 	    goto done;
 	}
+    }
+    if (stat(path, &sb) != 0) {
+	warning("%s", path);
+	goto done;
+    }
+    if (sb.st_uid != ROOT_UID) {
+	warningx(_("%s must be owned by uid %d"), path, ROOT_UID);
+	goto done;
+    }
+    if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
+	warningx(_("%s must be only be writable by owner"), path);
+	goto done;
+    }
 
-	/* Open plugin and map in symbol */
-	handle = dlopen(path, RTLD_LAZY|RTLD_GLOBAL);
-	if (!handle) {
-	    warningx(_("unable to dlopen %s: %s"), path, dlerror());
-	    goto done;
-	}
-	plugin = dlsym(handle, info->symbol_name);
-	if (!plugin) {
-	    warningx(_("%s: unable to find symbol %s"), path,
-		info->symbol_name);
+    /* Open plugin and map in symbol */
+    handle = dlopen(path, RTLD_LAZY|RTLD_GLOBAL);
+    if (!handle) {
+	warningx(_("unable to dlopen %s: %s"), path, dlerror());
+	goto done;
+    }
+    plugin = dlsym(handle, info->symbol_name);
+    if (!plugin) {
+	warningx(_("%s: unable to find symbol %s"), path,
+	    info->symbol_name);
+	goto done;
+    }
+
+    if (plugin->type != SUDO_POLICY_PLUGIN && plugin->type != SUDO_IO_PLUGIN) {
+	warningx(_("%s: unknown policy type %d"), path, plugin->type);
+	goto done;
+    }
+    if (SUDO_API_VERSION_GET_MAJOR(plugin->version) != SUDO_API_VERSION_MAJOR) {
+	warningx(_("%s: incompatible policy major version %d, expected %d"),
+	    path, SUDO_API_VERSION_GET_MAJOR(plugin->version),
+	    SUDO_API_VERSION_MAJOR);
+	goto done;
+    }
+    if (plugin->type == SUDO_POLICY_PLUGIN) {
+	if (policy_plugin->handle) {
+	    warningx(_("%s: only a single policy plugin may be loaded"),
+		_PATH_SUDO_CONF);
 	    goto done;
 	}
+	policy_plugin->handle = handle;
+	policy_plugin->name = info->symbol_name;
+	policy_plugin->options = info->options;
+	policy_plugin->u.generic = plugin;
+    } else if (plugin->type == SUDO_IO_PLUGIN) {
+	container = ecalloc(1, sizeof(*container));
+	container->prev = container;
+	/* container->next = NULL; */
+	container->handle = handle;
+	container->name = info->symbol_name;
+	container->options = info->options;
+	container->u.generic = plugin;
+	tq_append(io_plugins, container);
+    }
 
-	if (plugin->type != SUDO_POLICY_PLUGIN && plugin->type != SUDO_IO_PLUGIN) {
-	    warningx(_("%s: unknown policy type %d"), path, plugin->type);
+    rval = true;
+done:
+    debug_return_bool(rval);
+}
+
+/*
+ * Load the plugins listed in sudo.conf.
+ */
+bool
+sudo_load_plugins(struct plugin_container *policy_plugin,
+    struct plugin_container_list *io_plugins)
+{
+    struct plugin_container *container;
+    struct plugin_info_list *plugins;
+    struct plugin_info *info;
+    bool rval = false;
+    debug_decl(sudo_load_plugins, SUDO_DEBUG_PLUGIN)
+
+    /* Walk the plugin list from sudo.conf, if any. */
+    plugins = sudo_conf_plugins();
+    tq_foreach_fwd(plugins, info) {
+	rval = sudo_load_plugin(policy_plugin, io_plugins, info);
+	if (!rval)
 	    goto done;
-	}
-	if (SUDO_API_VERSION_GET_MAJOR(plugin->version) != SUDO_API_VERSION_MAJOR) {
-	    warningx(_("%s: incompatible policy major version %d, expected %d"),
-		path, SUDO_API_VERSION_GET_MAJOR(plugin->version),
-		SUDO_API_VERSION_MAJOR);
+    }
+
+    /*
+     * If no policy plugin, fall back to the default (sudoers).
+     * If there is also no I/O log plugin, sudoers for that too.
+     */
+    if (policy_plugin->handle == NULL) {
+	/* Default policy plugin */
+	info = ecalloc(1, sizeof(*info));
+	info->symbol_name = "sudoers_policy";
+	info->path = SUDOERS_PLUGIN;
+	/* info->options = NULL; */
+	info->prev = info;
+	/* info->next = NULL; */
+	rval = sudo_load_plugin(policy_plugin, io_plugins, info);
+	efree(info);
+	if (!rval)
 	    goto done;
-	}
-	if (plugin->type == SUDO_POLICY_PLUGIN) {
-	    if (policy_plugin->handle) {
-		warningx(_("%s: only a single policy plugin may be loaded"),
-		    _PATH_SUDO_CONF);
+
+	/* Default I/O plugin */
+	if (tq_empty(io_plugins)) {
+	    info = ecalloc(1, sizeof(*info));
+	    info->symbol_name = "sudoers_io";
+	    info->path = SUDOERS_PLUGIN;
+	    /* info->options = NULL; */
+	    info->prev = info;
+	    /* info->next = NULL; */
+	    rval = sudo_load_plugin(policy_plugin, io_plugins, info);
+	    efree(info);
+	    if (!rval)
 		goto done;
-	    }
-	    policy_plugin->handle = handle;
-	    policy_plugin->name = info->symbol_name;
-	    policy_plugin->options = info->options;
-	    policy_plugin->u.generic = plugin;
-	} else if (plugin->type == SUDO_IO_PLUGIN) {
-	    container = ecalloc(1, sizeof(*container));
-	    container->prev = container;
-	    /* container->next = NULL; */
-	    container->handle = handle;
-	    container->name = info->symbol_name;
-	    container->options = info->options;
-	    container->u.generic = plugin;
-	    tq_append(io_plugins, container);
 	}
     }
-    if (policy_plugin->handle == NULL) {
-	warningx(_("%s: at least one policy plugin must be specified"),
-	    _PATH_SUDO_CONF);
-	goto done;
-    }
     if (policy_plugin->u.policy->check_policy == NULL) {
 	warningx(_("policy plugin %s does not include a check_policy method"),
 	    policy_plugin->name);
+	rval = false;
 	goto done;
     }
 
@@ -165,8 +213,6 @@ sudo_load_plugins(struct plugin_container *policy_plugin,
 	}
     }
 
-    rval = true;
-
 done:
     debug_return_bool(rval);
 }
-- 
2.50.1