mirror of https://github.com/sudo-project/sudo.git
518 lines
13 KiB
C
518 lines
13 KiB
C
/*
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* SPDX-License-Identifier: ISC
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*
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* Copyright (c) 2010-2016, 2022 Todd C. Miller <Todd.Miller@sudo.ws>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* This is an open source non-commercial project. Dear PVS-Studio, please check it.
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* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
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*/
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#include <config.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#ifdef HAVE_STDBOOL_H
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# include <stdbool.h>
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#else
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# include <compat/stdbool.h>
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#endif /* HAVE_STDBOOL_H */
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#include <string.h>
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#ifdef HAVE_STRINGS_H
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# include <strings.h>
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#endif /* HAVE_STRINGS_H */
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#include <unistd.h>
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#include <ctype.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <grp.h>
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#include <pwd.h>
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#include <pathnames.h>
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#include <sudo_compat.h>
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#include <sudo_plugin.h>
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#include <sudo_util.h>
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/*
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* Sample plugin module that allows any user who knows the password
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* ("test") to run any command as root. Since there is no credential
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* caching the validate and invalidate functions are NULL.
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*/
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static struct plugin_state {
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char **envp;
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char * const *settings;
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char * const *user_info;
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} plugin_state;
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static sudo_conv_t sudo_conv;
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static sudo_printf_t sudo_log;
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static FILE *input, *output;
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static uid_t runas_uid = ROOT_UID;
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static gid_t runas_gid = (gid_t)-1;
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static int use_sudoedit = false;
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/*
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* Plugin policy open function.
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*/
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static int
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policy_open(unsigned int version, sudo_conv_t conversation,
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sudo_printf_t sudo_plugin_printf, char * const settings[],
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char * const user_info[], char * const user_env[], char * const args[],
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const char **errstr)
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{
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char * const *ui;
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struct passwd *pw;
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const char *runas_user = NULL;
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struct group *gr;
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const char *runas_group = NULL;
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if (!sudo_conv)
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sudo_conv = conversation;
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if (!sudo_log)
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sudo_log = sudo_plugin_printf;
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if (SUDO_API_VERSION_GET_MAJOR(version) != SUDO_API_VERSION_MAJOR) {
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sudo_log(SUDO_CONV_ERROR_MSG,
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"the sample plugin requires API version %d.x\n",
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SUDO_API_VERSION_MAJOR);
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return -1;
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}
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/* Only allow commands to be run as root. */
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for (ui = settings; *ui != NULL; ui++) {
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if (strncmp(*ui, "runas_user=", sizeof("runas_user=") - 1) == 0) {
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runas_user = *ui + sizeof("runas_user=") - 1;
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}
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if (strncmp(*ui, "runas_group=", sizeof("runas_group=") - 1) == 0) {
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runas_group = *ui + sizeof("runas_group=") - 1;
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}
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if (strncmp(*ui, "progname=", sizeof("progname=") - 1) == 0) {
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initprogname(*ui + sizeof("progname=") - 1);
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}
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/* Check to see if sudo was called as sudoedit or with -e flag. */
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if (strncmp(*ui, "sudoedit=", sizeof("sudoedit=") - 1) == 0) {
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if (strcasecmp(*ui + sizeof("sudoedit=") - 1, "true") == 0)
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use_sudoedit = true;
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}
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/* This plugin doesn't support running sudo with no arguments. */
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if (strncmp(*ui, "implied_shell=", sizeof("implied_shell=") - 1) == 0) {
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if (strcasecmp(*ui + sizeof("implied_shell=") - 1, "true") == 0)
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return -2; /* usage error */
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}
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}
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if (runas_user != NULL) {
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if ((pw = getpwnam(runas_user)) == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "unknown user %s\n", runas_user);
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return 0;
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}
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runas_uid = pw->pw_uid;
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}
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if (runas_group != NULL) {
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if ((gr = getgrnam(runas_group)) == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "unknown group %s\n", runas_group);
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return 0;
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}
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runas_gid = gr->gr_gid;
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}
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/* Plugin state. */
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plugin_state.envp = (char **)user_env;
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plugin_state.settings = settings;
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plugin_state.user_info = user_info;
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return 1;
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}
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static char *
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find_in_path(char *command, char **envp)
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{
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struct stat sb;
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char *path = NULL;
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char *path0, **ep, *cp;
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char pathbuf[PATH_MAX], *qualified = NULL;
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if (strchr(command, '/') != NULL)
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return command;
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for (ep = plugin_state.envp; *ep != NULL; ep++) {
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if (strncmp(*ep, "PATH=", 5) == 0) {
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path = *ep + 5;
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break;
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}
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}
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path = path0 = strdup(path ? path : _PATH_DEFPATH);
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do {
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if ((cp = strchr(path, ':')))
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*cp = '\0';
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snprintf(pathbuf, sizeof(pathbuf), "%s/%s", *path ? path : ".",
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command);
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if (stat(pathbuf, &sb) == 0) {
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if (S_ISREG(sb.st_mode) && (sb.st_mode & 0000111)) {
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qualified = pathbuf;
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break;
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}
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}
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path = cp + 1;
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} while (cp != NULL);
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free(path0);
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return qualified ? strdup(qualified) : NULL;
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}
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static int
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check_passwd(void)
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{
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struct sudo_conv_message msg;
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struct sudo_conv_reply repl;
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/* Prompt user for password via conversation function. */
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memset(&msg, 0, sizeof(msg));
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msg.msg_type = SUDO_CONV_PROMPT_ECHO_OFF;
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msg.msg = "Password: ";
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memset(&repl, 0, sizeof(repl));
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sudo_conv(1, &msg, &repl, NULL);
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if (repl.reply == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "missing password\n");
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return false;
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}
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if (strcmp(repl.reply, "test") != 0) {
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sudo_log(SUDO_CONV_ERROR_MSG, "incorrect password\n");
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return false;
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}
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return true;
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}
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static char **
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build_command_info(const char *command)
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{
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char **command_info;
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int i = 0;
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/* Setup command info. */
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command_info = calloc(32, sizeof(char *));
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if (command_info == NULL)
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goto oom;
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if ((command_info[i] = sudo_new_key_val("command", command)) == NULL)
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goto oom;
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i++;
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if (asprintf(&command_info[i], "runas_euid=%ld", (long)runas_uid) == -1)
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goto oom;
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i++;
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if (asprintf(&command_info[i++], "runas_uid=%ld", (long)runas_uid) == -1)
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goto oom;
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i++;
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if (runas_gid != (gid_t)-1) {
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if (asprintf(&command_info[i++], "runas_gid=%ld", (long)runas_gid) == -1)
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goto oom;
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i++;
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if (asprintf(&command_info[i++], "runas_egid=%ld", (long)runas_gid) == -1)
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goto oom;
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i++;
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}
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#ifdef USE_TIMEOUT
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if ((command_info[i] = strdup("timeout=30")) == NULL)
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goto oom;
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i++;
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#endif
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if (use_sudoedit) {
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if ((command_info[i] = strdup("sudoedit=true")) == NULL)
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goto oom;
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}
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return command_info;
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oom:
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while (i > 0) {
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free(command_info[i--]);
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}
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free(command_info);
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return NULL;
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}
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static char *
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find_editor(int nfiles, char * const files[], char **argv_out[])
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{
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char *cp, *last, **ep, **nargv, *editor_path;
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char *editor = NULL;
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int ac, i, nargc, wasblank;
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/* Lookup EDITOR in user's environment. */
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for (ep = plugin_state.envp; *ep != NULL; ep++) {
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if (strncmp(*ep, "EDITOR=", 7) == 0) {
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editor = *ep + 7;
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break;
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}
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}
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editor = strdup(editor ? editor : _PATH_VI);
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if (editor == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "unable to allocate memory\n");
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return NULL;
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}
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/*
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* Split editor into an argument vector; editor is reused (do not free).
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* The EDITOR environment variables may contain command
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* line args so look for those and alloc space for them too.
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*/
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nargc = 1;
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for (wasblank = 0, cp = editor; *cp != '\0'; cp++) {
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if (isblank((unsigned char) *cp))
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wasblank = 1;
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else if (wasblank) {
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wasblank = 0;
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nargc++;
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}
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}
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/* If we can't find the editor in the user's PATH, give up. */
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cp = strtok_r(editor, " \t", &last);
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if (cp == NULL ||
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(editor_path = find_in_path(editor, plugin_state.envp)) == NULL) {
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free(editor);
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return NULL;
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}
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if (editor_path != editor)
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free(editor);
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nargv = reallocarray(NULL, (size_t)nargc + 1 + (size_t)nfiles + 1,
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sizeof(char *));
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if (nargv == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "unable to allocate memory\n");
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free(editor_path);
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return NULL;
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}
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for (ac = 0; cp != NULL && ac < nargc; ac++) {
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nargv[ac] = cp;
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cp = strtok_r(NULL, " \t", &last);
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}
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nargv[ac++] = (char *)"--";
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for (i = 0; i < nfiles; )
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nargv[ac++] = files[i++];
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nargv[ac] = NULL;
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*argv_out = nargv;
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return editor_path;
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}
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/*
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* Plugin policy check function.
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* Simple example that prompts for a password, hard-coded to "test".
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*/
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static int
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policy_check(int argc, char * const argv[],
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char *env_add[], char **command_info_out[],
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char **argv_out[], char **user_env_out[], const char **errstr)
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{
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char *command;
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if (!argc || argv[0] == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "no command specified\n");
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return false;
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}
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if (!check_passwd())
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return false;
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command = find_in_path(argv[0], plugin_state.envp);
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if (command == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "%s: command not found\n", argv[0]);
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return false;
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}
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/* If "sudo vi" is run, auto-convert to sudoedit. */
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if (strcmp(command, _PATH_VI) == 0)
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use_sudoedit = true;
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if (use_sudoedit) {
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/* Rebuild argv using editor */
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free(command);
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command = find_editor(argc - 1, argv + 1, argv_out);
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if (command == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "unable to find valid editor\n");
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return -1;
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}
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use_sudoedit = true;
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} else {
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/* No changes needed to argv */
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*argv_out = (char **)argv;
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}
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/* No changes to envp */
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*user_env_out = plugin_state.envp;
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/* Setup command info. */
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*command_info_out = build_command_info(command);
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free(command);
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if (*command_info_out == NULL) {
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sudo_log(SUDO_CONV_ERROR_MSG, "out of memory\n");
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return -1;
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}
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return true;
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}
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static int
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policy_list(int argc, char * const argv[], int verbose, const char *list_user,
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const char **errstr)
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{
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/*
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* List user's capabilities.
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*/
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sudo_log(SUDO_CONV_INFO_MSG, "Validated users may run any command\n");
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return true;
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}
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static int
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policy_version(int verbose)
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{
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sudo_log(SUDO_CONV_INFO_MSG, "Sample policy plugin version %s\n",
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PACKAGE_VERSION);
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return true;
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}
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static void
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policy_close(int exit_status, int error)
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{
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/*
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* The policy might log the command exit status here.
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* In this example, we just print a message.
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*/
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if (error) {
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sudo_log(SUDO_CONV_ERROR_MSG, "Command error: %s\n", strerror(error));
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} else {
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if (WIFEXITED(exit_status)) {
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sudo_log(SUDO_CONV_INFO_MSG, "Command exited with status %d\n",
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WEXITSTATUS(exit_status));
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} else if (WIFSIGNALED(exit_status)) {
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sudo_log(SUDO_CONV_INFO_MSG, "Command killed by signal %d\n",
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WTERMSIG(exit_status));
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}
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}
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}
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static int
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io_open(unsigned int version, sudo_conv_t conversation,
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sudo_printf_t sudo_plugin_printf, char * const settings[],
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char * const user_info[], char * const command_info[],
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int argc, char * const argv[], char * const user_env[], char * const args[],
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const char **errstr)
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{
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int fd;
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char path[PATH_MAX];
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if (!sudo_conv)
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sudo_conv = conversation;
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if (!sudo_log)
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sudo_log = sudo_plugin_printf;
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/* Open input and output files. */
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snprintf(path, sizeof(path), "/var/tmp/sample-%u.output",
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(unsigned int)getpid());
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fd = open(path, O_WRONLY|O_CREAT|O_EXCL, 0644);
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if (fd == -1)
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return false;
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output = fdopen(fd, "w");
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snprintf(path, sizeof(path), "/var/tmp/sample-%u.input",
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(unsigned int)getpid());
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fd = open(path, O_WRONLY|O_CREAT|O_EXCL, 0644);
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if (fd == -1)
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return false;
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input = fdopen(fd, "w");
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return true;
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}
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static void
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io_close(int exit_status, int error)
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{
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fclose(input);
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fclose(output);
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}
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static int
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io_version(int verbose)
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{
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sudo_log(SUDO_CONV_INFO_MSG, "Sample I/O plugin version %s\n",
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PACKAGE_VERSION);
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return true;
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}
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static int
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io_log_input(const char *buf, unsigned int len, const char **errstr)
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{
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ignore_result(fwrite(buf, len, 1, input));
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return true;
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}
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static int
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io_log_output(const char *buf, unsigned int len, const char **errstr)
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{
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const char *cp, *ep;
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bool ret = true;
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ignore_result(fwrite(buf, len, 1, output));
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/*
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* If we find the string "honk!" in the buffer, reject it.
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* In practice we'd want to be able to detect the word
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* broken across two buffers.
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*/
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for (cp = buf, ep = buf + len; cp < ep; cp++) {
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if (cp + 5 < ep && memcmp(cp, "honk!", 5) == 0) {
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ret = false;
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break;
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}
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}
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return ret;
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}
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sudo_dso_public struct policy_plugin sample_policy = {
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SUDO_POLICY_PLUGIN,
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SUDO_API_VERSION,
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policy_open,
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policy_close,
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policy_version,
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policy_check,
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policy_list,
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NULL, /* validate */
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NULL, /* invalidate */
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NULL, /* init_session */
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NULL, /* register_hooks */
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NULL, /* deregister_hooks */
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NULL /* event_alloc() filled in by sudo */
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};
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/*
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* Note: This plugin does not differentiate between tty and pipe I/O.
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* It all gets logged to the same file.
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*/
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sudo_dso_public struct io_plugin sample_io = {
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SUDO_IO_PLUGIN,
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SUDO_API_VERSION,
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io_open,
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io_close,
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io_version,
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io_log_input, /* tty input */
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io_log_output, /* tty output */
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io_log_input, /* command stdin if not tty */
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io_log_output, /* command stdout if not tty */
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io_log_output, /* command stderr if not tty */
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NULL, /* register_hooks */
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NULL, /* deregister_hooks */
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NULL, /* change_winsize */
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NULL, /* log_suspend */
|
|
NULL /* event_alloc() filled in by sudo */
|
|
};
|