Replace built-in non-unix group support with a sudoers group plugin.

Include a sample plugin that can read Unix-format group files.

plugins/sudoers/group_plugin.c

@@ -0,0 +1,163 @@
+/*
+ * Copyright (c) 2010 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <stdio.h>
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif /* STDC_HEADERS */
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif /* HAVE_UNISTD_H */
+#if TIME_WITH_SYS_TIME
+# include <time.h>
+#endif
+#include <ctype.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <pwd.h>
+
+#include "sudoers.h"
+
+static void *group_handle;
+static struct sudoers_group_plugin *group_plugin;
+
+/*
+ * Load the specified plugin and run its init function.
+ * Returns -1 if unable to open the plugin, else it returns
+ * the value from the plugin's init function.
+ */
+int
+group_plugin_load(char *plugin_info)
+{
+    struct stat sb;
+    char *args, path[PATH_MAX], savedch;
+    char **argv = NULL;
+    size_t len;
+    int rc;
+
+    /*
+     * Fill in .so path and split out args (if any).
+     */
+    path[0] = '\0';
+    if (plugin_info[0] != '/')
+	strlcpy(path, _PATH_SUDO_PLUGIN_DIR, sizeof(path));
+    if ((args = strpbrk(plugin_info, " \t")) != NULL) {
+	savedch = *args;
+	*args = '\0';
+    }
+    len = strlcat(path, plugin_info, sizeof(path));
+    if (args != NULL)
+	*args++ = savedch;
+    if (len >= sizeof(path)) {
+	warningx("%s%s: %s", _PATH_SUDO_PLUGIN_DIR, plugin_info,
+	    strerror(ENAMETOOLONG));
+	return -1;
+    }
+
+    /* Sanity check plugin path. */
+    if (stat(path, &sb) != 0) {
+	warning("%s", path);
+	return -1;
+    }
+    if (sb.st_uid != ROOT_UID) {
+	warningx("%s must be owned by uid %d", path, ROOT_UID);
+	return -1;
+    }
+    if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
+	warningx("%s must be only be writable by owner", path);
+	return -1;
+    }
+
+    /* Open plugin and map in symbol. */
+    group_handle = dlopen(path, RTLD_NOW);
+    if (!group_handle) {
+	warningx("unable to dlopen %s: %s", path, dlerror());
+	return -1;
+    }
+    group_plugin = dlsym(group_handle, "group_plugin");
+    if (group_plugin == NULL) {
+	warningx("unable to find symbol \"group_plugin\" in %s", path);
+	return -1;
+    }
+
+    if (GROUP_API_VERSION_GET_MAJOR(group_plugin->version) != GROUP_API_VERSION_MAJOR) {
+	warningx("%s: incompatible group plugin major version %d, expected %d",
+	    path, GROUP_API_VERSION_GET_MAJOR(group_plugin->version),
+	    GROUP_API_VERSION_MAJOR);
+	return -1;
+    }
+
+    /*
+     * Split args into a vector if specified.
+     */
+    if (args != NULL) {
+	int ac = 0, wasblank = TRUE;
+	char *cp;
+
+        for (cp = args; *cp != '\0'; cp++) {
+            if (isblank((unsigned char)*cp)) {
+                wasblank = TRUE;
+            } else if (wasblank) {
+                wasblank = FALSE;
+                ac++;
+            }
+        }
+	if (ac != 0) 	{
+	    argv = emalloc2(ac, sizeof(char *));
+	    ac = 0;
+	    for ((cp = strtok(args, " \t")); cp; (cp = strtok(NULL, " \t")))
+		argv[ac++] = cp;
+	}
+    }
+
+    rc = (group_plugin->init)(GROUP_API_VERSION, sudo_printf, argv);
+
+    efree(argv);
+
+    return rc;
+}
+
+void
+group_plugin_unload(void)
+{
+    (group_plugin->cleanup)();
+    dlclose(group_handle);
+    group_handle = NULL;
+}
+
+int
+group_plugin_query(const char *user, const char *group,
+    const struct passwd *pwd)
+{
+    return (group_plugin->query)(user, group, pwd);
+}