Load the sudoers module as an audit plugin if loaded as a policy plugin.

Now that logging of successful commands is performed by sudoers as an
audit plugin we need to load sudoers_audit if sudoers_policy is also
loaded.  Otherwise, accpted commands will not be logged.

doc/sudo.conf.man.in

@@ -2,7 +2,7 @@
 .\"
 .\" SPDX-License-Identifier: ISC
 .\"
-.\" Copyright (c) 2010-2019 Todd C. Miller <Todd.Miller@sudo.ws>
+.\" Copyright (c) 2010-2020 Todd C. Miller <Todd.Miller@sudo.ws>
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above
@@ -17,7 +17,7 @@
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
 .nr SL @SEMAN@
-.TH "SUDO.CONF" "@mansectform@" "October 20, 2019" "Sudo @PACKAGE_VERSION@" "File Formats Manual"
+.TH "SUDO.CONF" "@mansectform@" "June 1, 2020" "Sudo @PACKAGE_VERSION@" "File Formats Manual"
 .nh
 .if n .ad l
 .SH "NAME"
@@ -105,10 +105,15 @@ to the dynamic shared object that contains the plugin.
 The
 \fIsymbol_name\fR
 is the name of the
-\fRstruct policy_plugin\fR
+\fRapproval_plugin\fR,
+\fRaudit_plugin\fR,
+\fRio_plugin\fR,
 or
-\fRstruct io_plugin\fR
+\fRpolicy_plugin\fR
-symbol contained in the plugin.
+struct contained in the plugin.
+If a plugin implements multiple plugin types, there must be a
+\fRPlugin\fR
+line for each unique symbol name.
 The
 \fIpath\fR
 may be fully qualified or relative.
@@ -180,17 +185,35 @@ file is present, or if it contains no
 \fRPlugin\fR
 lines, the
 \fBsudoers\fR
-plugin will be used as the default security policy and for I/O logging
+plugin will be used as the default security policy, for I/O logging
-(if enabled by the policy).
+(if enabled by the policy) and for auditing.
 This is equivalent to the following:
 .nf
 .sp
 .RS 6n
 Plugin sudoers_policy sudoers.so
 Plugin sudoers_io sudoers.so
+Plugin sudoers_audit sudoers.so
 .RE
 .fi
 .PP
+Starting with
+\fBsudo\fR
+version 1.9.1, some of the logging functionality of the
+\fBsudoers\fR
+plugin has been moved from the policy plugin to an audit plugin.
+To maintain compatibility with
+\fBsudo.conf\fR
+files from older
+\fBsudo\fR
+versions, if
+\fBsudoers\fR
+is configured as the security policy, it will be used as an audit
+plugin as well.
+This guarantees that the logging behavior will be consistnet with that of
+\fBsudo\fR
+versions 1.9.0 and below.
+.PP
 For more information on the
 \fBsudo\fR
 plugin architecture, see the
@@ -687,6 +710,7 @@ front end configuration
 # The sudoers plugin is used by default if no Plugin lines are present.
 Plugin sudoers_policy sudoers.so
 Plugin sudoers_io sudoers.so
+Plugin sudoers_audit sudoers.so
 
 #
 # Sudo askpass:

doc/sudo.conf.mdoc.in

@@ -1,7 +1,7 @@
 .\"
 .\" SPDX-License-Identifier: ISC
 .\"
-.\" Copyright (c) 2010-2019 Todd C. Miller <Todd.Miller@sudo.ws>
+.\" Copyright (c) 2010-2020 Todd C. Miller <Todd.Miller@sudo.ws>
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above
@@ -16,7 +16,7 @@
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
 .nr SL @SEMAN@
-.Dd October 20, 2019
+.Dd June 1, 2020
 .Dt SUDO.CONF @mansectform@
 .Os Sudo @PACKAGE_VERSION@
 .Sh NAME
@@ -102,10 +102,15 @@ to the dynamic shared object that contains the plugin.
 The
 .Em symbol_name
 is the name of the
-.Li struct policy_plugin
+.Li approval_plugin ,
+.Li audit_plugin ,
+.Li io_plugin ,
 or
-.Li struct io_plugin
+.Li policy_plugin
-symbol contained in the plugin.
+struct contained in the plugin.
+If a plugin implements multiple plugin types, there must be a
+.Li Plugin
+line for each unique symbol name.
 The
 .Em path
 may be fully qualified or relative.
@@ -165,14 +170,32 @@ file is present, or if it contains no
 .Li Plugin
 lines, the
 .Nm sudoers
-plugin will be used as the default security policy and for I/O logging
+plugin will be used as the default security policy, for I/O logging
-(if enabled by the policy).
+(if enabled by the policy) and for auditing.
 This is equivalent to the following:
 .Bd -literal -offset indent
 Plugin sudoers_policy sudoers.so
 Plugin sudoers_io sudoers.so
+Plugin sudoers_audit sudoers.so
 .Ed
 .Pp
+Starting with
+.Nm sudo
+version 1.9.1, some of the logging functionality of the
+.Nm sudoers
+plugin has been moved from the policy plugin to an audit plugin.
+To maintain compatibility with
+.Nm
+files from older
+.Nm sudo
+versions, if
+.Nm sudoers
+is configured as the security policy, it will be used as an audit
+plugin as well.
+This guarantees that the logging behavior will be consistnet with that of
+.Nm sudo
+versions 1.9.0 and below.
+.Pp
 For more information on the
 .Nm sudo
 plugin architecture, see the
@@ -621,6 +644,7 @@ front end configuration
 # The sudoers plugin is used by default if no Plugin lines are present.
 Plugin sudoers_policy sudoers.so
 Plugin sudoers_io sudoers.so
+Plugin sudoers_audit sudoers.so
 
 #
 # Sudo askpass:

src/load_plugins.c

@@ -198,13 +198,13 @@ bad:
 }
 
 static bool
-plugin_exists(struct plugin_container_list *plugins, struct plugin_info *info)
+plugin_exists(struct plugin_container_list *plugins, const char *symbol_name)
 {
     struct plugin_container *container;
     debug_decl(find_plugin, SUDO_DEBUG_PLUGIN);
 
     TAILQ_FOREACH(container, plugins, entries) {
-	if (strcmp(container->name, info->symbol_name) == 0)
+	if (strcmp(container->name, symbol_name) == 0)
 	    debug_return_bool(true);
     }
     debug_return_bool(false);
@@ -241,7 +241,7 @@ sudo_insert_plugin(struct plugin_container_list *plugin_list, void *handle,
     struct plugin_container *container;
     debug_decl(sudo_insert_plugin, SUDO_DEBUG_PLUGIN);
 
-    if (plugin_exists(plugin_list, info)) {
+    if (plugin_exists(plugin_list, info->symbol_name)) {
 	plugin = sudo_plugin_try_to_clone(handle, info->symbol_name);
 	if (plugin == NULL) {
 	    sudo_warnx(U_("ignoring duplicate plugin \"%s\" in %s, line %d"),
@@ -267,7 +267,7 @@ sudo_load_plugin(struct plugin_container *policy_plugin,
     struct plugin_container_list *io_plugins,
     struct plugin_container_list *audit_plugins,
     struct plugin_container_list *approval_plugins,
-    struct plugin_info *info)
+    struct plugin_info *info, bool quiet)
 {
     struct generic_plugin *plugin;
     char path[PATH_MAX];
@@ -282,27 +282,34 @@ sudo_load_plugin(struct plugin_container *policy_plugin,
     /* Open plugin and map in symbol */
     handle = sudo_dso_load(path, SUDO_DSO_LAZY|SUDO_DSO_GLOBAL);
     if (!handle) {
+	if (!quiet) {
 	    const char *errstr = sudo_dso_strerror();
 	    sudo_warnx(U_("error in %s, line %d while loading plugin \"%s\""),
 		_PATH_SUDO_CONF, info->lineno, info->symbol_name);
 	    sudo_warnx(U_("unable to load %s: %s"), path,
 		errstr ? errstr : "unknown error");
+	}
 	goto done;
     }
     plugin = sudo_dso_findsym(handle, info->symbol_name);
     if (!plugin) {
+	if (!quiet) {
 	    sudo_warnx(U_("error in %s, line %d while loading plugin \"%s\""),
 		_PATH_SUDO_CONF, info->lineno, info->symbol_name);
-	sudo_warnx(U_("unable to find symbol \"%s\" in %s"), info->symbol_name, path);
+	    sudo_warnx(U_("unable to find symbol \"%s\" in %s"),
+		info->symbol_name, path);
+	}
 	goto done;
     }
 
     if (SUDO_API_VERSION_GET_MAJOR(plugin->version) != SUDO_API_VERSION_MAJOR) {
+	if (!quiet) {
 	    sudo_warnx(U_("error in %s, line %d while loading plugin \"%s\""),
 		_PATH_SUDO_CONF, info->lineno, info->symbol_name);
 	    sudo_warnx(U_("incompatible plugin major version %d (expected %d) found in %s"),
 		SUDO_API_VERSION_GET_MAJOR(plugin->version),
 		SUDO_API_VERSION_MAJOR, path);
+	}
 	goto done;
     }
 
@@ -311,12 +318,16 @@ sudo_load_plugin(struct plugin_container *policy_plugin,
 	if (policy_plugin->handle != NULL) {
 	    /* Ignore duplicate entries. */
 	    if (strcmp(policy_plugin->name, info->symbol_name) == 0) {
+		if (!quiet) {
 		    sudo_warnx(U_("ignoring duplicate plugin \"%s\" in %s, line %d"),
 			info->symbol_name, _PATH_SUDO_CONF, info->lineno);
+		}
 	    } else {
+		if (!quiet) {
 		    sudo_warnx(U_("ignoring policy plugin \"%s\" in %s, line %d"),
 			info->symbol_name, _PATH_SUDO_CONF, info->lineno);
 		    sudo_warnx(U_("only a single policy plugin may be specified"));
+		}
 		goto done;
 	    }
 	    ret = true;
@@ -338,9 +349,11 @@ sudo_load_plugin(struct plugin_container *policy_plugin,
 	    goto done;
 	break;
     default:
+	if (!quiet) {
 	    sudo_warnx(U_("error in %s, line %d while loading plugin \"%s\""),
 		_PATH_SUDO_CONF, info->lineno, info->symbol_name);
 	    sudo_warnx(U_("unknown plugin type %d found in %s"), plugin->type, path);
+	}
 	goto done;
     }
 
@@ -427,6 +440,44 @@ sudo_init_event_alloc(struct plugin_container *policy_plugin,
     debug_return;
 }
 
+/*
+ * Load the specified symbol from the sudoers plugin.
+ * Used to provide a default plugin when none are specified in sudo.conf.
+ */
+bool
+sudo_load_sudoers_plugin(const char *symbol_name,
+    struct plugin_container *policy_plugin,
+    struct plugin_container_list *io_plugins,
+    struct plugin_container_list *audit_plugins,
+    struct plugin_container_list *approval_plugins,
+    bool optional)
+{
+    struct plugin_info *info;
+    bool ret = false;
+    debug_decl(sudo_load_sudoers_plugin, SUDO_DEBUG_PLUGIN);
+
+    /* Default policy plugin */
+    info = calloc(1, sizeof(*info));
+    if (info == NULL) {
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	goto done;
+    }
+    info->symbol_name = strdup(symbol_name);
+    info->path = strdup(SUDOERS_PLUGIN);
+    if (info->symbol_name == NULL || info->path == NULL) {
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	free_plugin_info(info);
+	goto done;
+    }
+    /* info->options = NULL; */
+    ret = sudo_load_plugin(policy_plugin, io_plugins, audit_plugins,
+	approval_plugins, info, optional);
+    free_plugin_info(info);
+
+done:
+    debug_return_bool(ret);
+}
+
 /*
  * Load the plugins listed in sudo.conf.
  */
@@ -445,7 +496,7 @@ sudo_load_plugins(struct plugin_container *policy_plugin,
     plugins = sudo_conf_plugins();
     TAILQ_FOREACH_SAFE(info, plugins, entries, next) {
 	ret = sudo_load_plugin(policy_plugin, io_plugins, audit_plugins,
-	    approval_plugins, info);
+	    approval_plugins, info, false);
 	if (!ret)
 	    goto done;
 	free_plugin_info(info);
@@ -458,47 +509,33 @@ sudo_load_plugins(struct plugin_container *policy_plugin,
      */
     if (policy_plugin->handle == NULL) {
 	/* Default policy plugin */
-	info = calloc(1, sizeof(*info));
+	ret = sudo_load_sudoers_plugin("sudoers_policy", policy_plugin,
-	if (info == NULL) {
+	    io_plugins, audit_plugins, approval_plugins, false);
-	    sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
-	    goto done;
-	}
-	info->symbol_name = strdup("sudoers_policy");
-	info->path = strdup(SUDOERS_PLUGIN);
-	if (info->symbol_name == NULL || info->path == NULL) {
-	    sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
-	    free_plugin_info(info);
-	    goto done;
-	}
-	/* info->options = NULL; */
-	ret = sudo_load_plugin(policy_plugin, io_plugins, audit_plugins,
-	    approval_plugins, info);
-	free_plugin_info(info);
 	if (!ret)
 	    goto done;
 
+	/* Default audit plugin, optional (sudoers < 1.9.1 lack this) */
+	(void)sudo_load_sudoers_plugin("sudoers_audit", policy_plugin,
+	    io_plugins, audit_plugins, approval_plugins, true);
+
 	/* Default I/O plugin */
 	if (TAILQ_EMPTY(io_plugins)) {
-	    info = calloc(1, sizeof(*info));
+	    ret = sudo_load_sudoers_plugin("sudoers_io", policy_plugin,
-	    if (info == NULL) {
+		io_plugins, audit_plugins, approval_plugins, false);
-		sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
-		goto done;
-	    }
-	    info->symbol_name = strdup("sudoers_io");
-	    info->path = strdup(SUDOERS_PLUGIN);
-	    if (info->symbol_name == NULL || info->path == NULL) {
-		sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
-		free_plugin_info(info);
-		goto done;
-	    }
-	    /* info->options = NULL; */
-	    ret = sudo_load_plugin(policy_plugin, io_plugins, audit_plugins,
-		approval_plugins, info);
-	    free_plugin_info(info);
 	    if (!ret)
 		goto done;
 	}
+    } else if (strcmp(policy_plugin->name, "sudoers_policy") == 0) {
+	/*
+	 * If policy plugin is sudoers_policy but there is no sudoers_audit
+	 * loaded, load it too, if possible.
+	 */
+	if (!plugin_exists(audit_plugins, "sudoers_audit")) {
+	    (void)sudo_load_sudoers_plugin("sudoers_audit", policy_plugin,
+		io_plugins, audit_plugins, approval_plugins, true);
 	}
+    }
+
     /* TODO: check all plugins for open function too */
     if (policy_plugin->u.policy->check_policy == NULL) {
 	sudo_warnx(U_("policy plugin %s does not include a check_policy method"),