Sample plugin demonstrating the sudo plugin API

plugins/sample/sample_plugin.c

@@ -0,0 +1,301 @@
+/*
+ * 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/wait.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
+# if defined(HAVE_MEMORY_H) && !defined(STDC_HEADERS)
+#  include <memory.h>
+# endif
+# include <string.h>
+#else
+# ifdef HAVE_STRINGS_H
+#  include <strings.h>
+# endif
+#endif /* HAVE_STRING_H */
+#include <stdarg.h>
+
+#include <sudo_plugin.h>
+
+/*
+ * Sample plugin module that allows any user who knows the password
+ * ("test") to run any command as root.  Since there is no credential
+ * caching the validate and invalidate functions are NULL.
+ */
+
+static struct plugin_state {
+    char **envp;
+    char * const *settings;
+    char * const *user_info;
+} plugin_state;
+static sudo_conv_t sudo_conv;
+
+#undef TRUE
+#define TRUE 1
+#undef FALSE
+#define FALSE 0
+#undef ERROR
+#define ERROR -1
+
+/*
+ * Allocate storage for a name=value string and return it.
+ */
+static char *
+fmt_string(const char *var, const char *val)
+{
+    size_t var_len = strlen(var);
+    size_t val_len = strlen(val);
+    char *cp, *str;
+
+    cp = str = malloc(var_len + 1 + val_len + 1);
+    if (!str)
+	return NULL;
+    memcpy(cp, var, var_len);
+    cp += var_len;
+    *cp++ = '=';
+    memcpy(cp, val, val_len);
+    cp += val_len;
+    *cp = '\0';
+
+    return(str);
+}
+
+/*
+ * Display warning via conversation function.
+ */
+static void
+sudo_log(int type, const char *fmt, ...)
+{
+    struct sudo_conv_message msg;
+    struct sudo_conv_reply repl;
+    va_list ap;
+    char *str;
+    int rc;
+
+    va_start(ap, fmt);
+    rc = vasprintf(&str, fmt, ap);
+    va_end(ap);
+    if (rc == -1)
+	return;
+
+    /* Call conversation function */
+    memset(&msg, 0, sizeof(msg));
+    msg.msg_type = type;
+    msg.msg = str;
+    memset(&repl, 0, sizeof(repl));
+    sudo_conv(1, &msg, &repl);
+}
+
+/*
+ * Plugin policy open function.
+ */
+static int
+policy_open(unsigned int version, sudo_conv_t conversation,
+    char * const settings[], char * const user_info[],
+    char * const user_env[])
+{
+    char * const *ui;
+    const char *runas_user = NULL;
+
+    sudo_conv = conversation;
+
+    if (SUDO_API_VERSION_GET_MAJOR(version) != SUDO_API_VERSION_MAJOR) {
+	sudo_log(SUDO_CONV_ERROR_MSG,
+	    "the sample plugin requires API version %d.x",
+	    SUDO_API_VERSION_MAJOR);
+	return ERROR;
+    }
+
+    /* Only allow commands to be run as root. */
+    for (ui = user_info; *ui != NULL; ui++) {
+	if (strncmp(*ui, "runas_user=", sizeof("runas_user=") - 1) == 0) {
+	    runas_user = *ui + sizeof("runas_user=") - 1;
+	}
+    }
+    if (runas_user && strcmp(runas_user, "root") != 0) {
+	sudo_log(SUDO_CONV_ERROR_MSG, "commands may only be run as root.");
+	return 0;
+    }
+
+    /* Plugin state. */
+    plugin_state.envp = (char **)user_env;
+    plugin_state.settings = settings;
+    plugin_state.user_info = user_info;
+
+    return 1;
+}
+
+/*
+ * Plugin policy check function.
+ * Simple example that prompts for a password, hard-coded to "test".
+ */
+static int 
+policy_check(int argc, char * const argv[],
+    char *env_add[], char **command_info_out[],
+    char **argv_out[], char **user_env_out[])
+{
+    struct sudo_conv_message msg;
+    struct sudo_conv_reply repl;
+    char **command_info;
+    int i = 0;
+
+    if (!argc || argv[0] == NULL) {
+	sudo_log(SUDO_CONV_ERROR_MSG, "no command specified");
+	return FALSE;
+    }
+    /* Only allow fully qualified paths to keep things simple. */
+    if (argv[0][0] != '/') {
+	sudo_log(SUDO_CONV_ERROR_MSG,
+	    "only fully qualified pathnames may be specified");
+	return FALSE;
+    }
+
+    /* Prompt user for password via conversation function. */
+    memset(&msg, 0, sizeof(msg));
+    msg.msg_type = SUDO_CONV_PROMPT_ECHO_OFF;
+    msg.msg = "Password: ";
+    memset(&repl, 0, sizeof(repl));
+    sudo_conv(1, &msg, &repl);
+    if (strcmp(repl.reply, "test") != 0) {
+	sudo_log(SUDO_CONV_ERROR_MSG, "incorrect password");
+	return FALSE;
+    }
+
+    /* No changes to argv or envp */
+    *argv_out = (char **)argv;
+    *user_env_out = plugin_state.envp;
+
+    /* Setup command info. */
+    command_info = calloc(32, sizeof(char *));
+    if (command_info == NULL) {
+	sudo_log(SUDO_CONV_ERROR_MSG, "out of memory");
+	return ERROR;
+    }
+    command_info[i++] = fmt_string("command", argv[0]);
+    command_info[i++] = "runas_uid=0";
+    command_info[i++] = "runas_euid=0";
+    *command_info_out = command_info;
+
+    return TRUE;
+}
+
+static int
+policy_list(int argc, char * const argv[], int verbose, const char *list_user)
+{
+    /*
+     * List user's capabilities.
+     */
+    sudo_log(SUDO_CONV_INFO_MSG, "Validated users may run any command");
+    return TRUE;
+}
+
+static int
+policy_version(int verbose)
+{
+    sudo_log(SUDO_CONV_INFO_MSG, "Sample policy plugin version %s", PACKAGE_VERSION);
+    return TRUE;
+}
+
+static void
+policy_close(int exit_status, int error)
+{
+    /*
+     * The policy might log the command exit status here.
+     * In this example, we just print a message.
+     */
+    if (error) {
+	sudo_log(SUDO_CONV_ERROR_MSG, "Command error: %s", strerror(error));
+    } else {
+        if (WIFEXITED(exit_status)) {
+	    sudo_log(SUDO_CONV_INFO_MSG, "Command exited with status %d",
+		WEXITSTATUS(exit_status));
+        } else if (WIFSIGNALED(exit_status)) {
+	    sudo_log(SUDO_CONV_INFO_MSG, "Command killed by signal %d",
+		WTERMSIG(exit_status));
+	}
+    }
+}
+
+static int
+io_open(unsigned int version, sudo_conv_t conversation,
+    char * const settings[], char * const user_info[],
+    char * const user_env[])
+{
+    /* TODO: something here */
+    return TRUE;
+}
+
+static void
+io_close(int exit_status, int error)
+{
+    /* TODO: something here */
+}
+
+static int
+io_version(int verbose)
+{
+    sudo_log(SUDO_CONV_INFO_MSG, "Sample I/O plugin version %s", PACKAGE_VERSION);
+    return TRUE;
+}
+
+static int
+io_log_input(const char *buf, unsigned int len)
+{
+    /* log nothing for now */
+    return TRUE;
+}
+
+static int
+io_log_output(const char *buf, unsigned int len)
+{
+    /* log nothing for now */
+    return TRUE;
+}
+
+struct policy_plugin sample_policy = {
+    SUDO_POLICY_PLUGIN,
+    SUDO_API_VERSION,
+    policy_open,
+    policy_close,
+    policy_version,
+    policy_check,
+    policy_list,
+    NULL, /* validate */
+    NULL /* invalidate */
+};
+
+struct io_plugin sample_io = {
+    SUDO_IO_PLUGIN,
+    SUDO_API_VERSION,
+    io_open,
+    io_close,
+    io_version,
+    io_log_input,
+    io_log_output
+};