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Diffstat (limited to 'plugins/sample/sample_plugin.c')
| -rw-r--r-- | plugins/sample/sample_plugin.c | 517 |
1 files changed, 517 insertions, 0 deletions
diff --git a/plugins/sample/sample_plugin.c b/plugins/sample/sample_plugin.c new file mode 100644 index 0000000..a529208 --- /dev/null +++ b/plugins/sample/sample_plugin.c @@ -0,0 +1,517 @@ +/* + * SPDX-License-Identifier: ISC + * + * Copyright (c) 2010-2016, 2022 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 + * 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. + */ + +/* + * This is an open source non-commercial project. Dear PVS-Studio, please check it. + * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com + */ + +#include <config.h> + +#include <sys/stat.h> +#include <sys/wait.h> + +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#ifdef HAVE_STDBOOL_H +# include <stdbool.h> +#else +# include <compat/stdbool.h> +#endif /* HAVE_STDBOOL_H */ +#include <string.h> +#ifdef HAVE_STRINGS_H +# include <strings.h> +#endif /* HAVE_STRINGS_H */ +#include <unistd.h> +#include <ctype.h> +#include <fcntl.h> +#include <limits.h> +#include <grp.h> +#include <pwd.h> + +#include <pathnames.h> +#include <sudo_compat.h> +#include <sudo_plugin.h> +#include <sudo_util.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; +static sudo_printf_t sudo_log; +static FILE *input, *output; +static uid_t runas_uid = ROOT_UID; +static gid_t runas_gid = (gid_t)-1; +static int use_sudoedit = false; + +/* + * Plugin policy open function. + */ +static int +policy_open(unsigned int version, sudo_conv_t conversation, + sudo_printf_t sudo_plugin_printf, char * const settings[], + char * const user_info[], char * const user_env[], char * const args[], + const char **errstr) +{ + char * const *ui; + struct passwd *pw; + const char *runas_user = NULL; + struct group *gr; + const char *runas_group = NULL; + + if (!sudo_conv) + sudo_conv = conversation; + if (!sudo_log) + sudo_log = sudo_plugin_printf; + + 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\n", + SUDO_API_VERSION_MAJOR); + return -1; + } + + /* Only allow commands to be run as root. */ + for (ui = settings; *ui != NULL; ui++) { + if (strncmp(*ui, "runas_user=", sizeof("runas_user=") - 1) == 0) { + runas_user = *ui + sizeof("runas_user=") - 1; + } + if (strncmp(*ui, "runas_group=", sizeof("runas_group=") - 1) == 0) { + runas_group = *ui + sizeof("runas_group=") - 1; + } + if (strncmp(*ui, "progname=", sizeof("progname=") - 1) == 0) { + initprogname(*ui + sizeof("progname=") - 1); + } + /* Check to see if sudo was called as sudoedit or with -e flag. */ + if (strncmp(*ui, "sudoedit=", sizeof("sudoedit=") - 1) == 0) { + if (strcasecmp(*ui + sizeof("sudoedit=") - 1, "true") == 0) + use_sudoedit = true; + } + /* This plugin doesn't support running sudo with no arguments. */ + if (strncmp(*ui, "implied_shell=", sizeof("implied_shell=") - 1) == 0) { + if (strcasecmp(*ui + sizeof("implied_shell=") - 1, "true") == 0) + return -2; /* usage error */ + } + } + if (runas_user != NULL) { + if ((pw = getpwnam(runas_user)) == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "unknown user %s\n", runas_user); + return 0; + } + runas_uid = pw->pw_uid; + } + if (runas_group != NULL) { + if ((gr = getgrnam(runas_group)) == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "unknown group %s\n", runas_group); + return 0; + } + runas_gid = gr->gr_gid; + } + + /* Plugin state. */ + plugin_state.envp = (char **)user_env; + plugin_state.settings = settings; + plugin_state.user_info = user_info; + + return 1; +} + +static char * +find_in_path(char *command, char **envp) +{ + struct stat sb; + char *path = NULL; + char *path0, **ep, *cp; + char pathbuf[PATH_MAX], *qualified = NULL; + + if (strchr(command, '/') != NULL) + return command; + + for (ep = plugin_state.envp; *ep != NULL; ep++) { + if (strncmp(*ep, "PATH=", 5) == 0) { + path = *ep + 5; + break; + } + } + path = path0 = strdup(path ? path : _PATH_DEFPATH); + do { + if ((cp = strchr(path, ':'))) + *cp = '\0'; + snprintf(pathbuf, sizeof(pathbuf), "%s/%s", *path ? path : ".", + command); + if (stat(pathbuf, &sb) == 0) { + if (S_ISREG(sb.st_mode) && (sb.st_mode & 0000111)) { + qualified = pathbuf; + break; + } + } + path = cp + 1; + } while (cp != NULL); + free(path0); + return qualified ? strdup(qualified) : NULL; +} + +static int +check_passwd(void) +{ + struct sudo_conv_message msg; + struct sudo_conv_reply repl; + + /* 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, NULL); + if (repl.reply == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "missing password\n"); + return false; + } + if (strcmp(repl.reply, "test") != 0) { + sudo_log(SUDO_CONV_ERROR_MSG, "incorrect password\n"); + return false; + } + return true; +} + +static char ** +build_command_info(const char *command) +{ + char **command_info; + int i = 0; + + /* Setup command info. */ + command_info = calloc(32, sizeof(char *)); + if (command_info == NULL) + goto oom; + if ((command_info[i] = sudo_new_key_val("command", command)) == NULL) + goto oom; + i++; + if (asprintf(&command_info[i], "runas_euid=%ld", (long)runas_uid) == -1) + goto oom; + i++; + if (asprintf(&command_info[i++], "runas_uid=%ld", (long)runas_uid) == -1) + goto oom; + i++; + if (runas_gid != (gid_t)-1) { + if (asprintf(&command_info[i++], "runas_gid=%ld", (long)runas_gid) == -1) + goto oom; + i++; + if (asprintf(&command_info[i++], "runas_egid=%ld", (long)runas_gid) == -1) + goto oom; + i++; + } +#ifdef USE_TIMEOUT + if ((command_info[i] = strdup("timeout=30")) == NULL) + goto oom; + i++; +#endif + if (use_sudoedit) { + if ((command_info[i] = strdup("sudoedit=true")) == NULL) + goto oom; + } + return command_info; +oom: + while (i > 0) { + free(command_info[i--]); + } + free(command_info); + return NULL; +} + +static char * +find_editor(int nfiles, char * const files[], char **argv_out[]) +{ + char *cp, *last, **ep, **nargv, *editor_path; + char *editor = NULL; + int ac, i, nargc, wasblank; + + /* Lookup EDITOR in user's environment. */ + for (ep = plugin_state.envp; *ep != NULL; ep++) { + if (strncmp(*ep, "EDITOR=", 7) == 0) { + editor = *ep + 7; + break; + } + } + editor = strdup(editor ? editor : _PATH_VI); + if (editor == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "unable to allocate memory\n"); + return NULL; + } + + /* + * Split editor into an argument vector; editor is reused (do not free). + * The EDITOR environment variables may contain command + * line args so look for those and alloc space for them too. + */ + nargc = 1; + for (wasblank = 0, cp = editor; *cp != '\0'; cp++) { + if (isblank((unsigned char) *cp)) + wasblank = 1; + else if (wasblank) { + wasblank = 0; + nargc++; + } + } + /* If we can't find the editor in the user's PATH, give up. */ + cp = strtok_r(editor, " \t", &last); + if (cp == NULL || + (editor_path = find_in_path(editor, plugin_state.envp)) == NULL) { + free(editor); + return NULL; + } + if (editor_path != editor) + free(editor); + nargv = reallocarray(NULL, (size_t)nargc + 1 + (size_t)nfiles + 1, + sizeof(char *)); + if (nargv == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "unable to allocate memory\n"); + free(editor_path); + return NULL; + } + for (ac = 0; cp != NULL && ac < nargc; ac++) { + nargv[ac] = cp; + cp = strtok_r(NULL, " \t", &last); + } + nargv[ac++] = (char *)"--"; + for (i = 0; i < nfiles; ) + nargv[ac++] = files[i++]; + nargv[ac] = NULL; + + *argv_out = nargv; + return editor_path; +} + +/* + * 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[], const char **errstr) +{ + char *command; + + if (!argc || argv[0] == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "no command specified\n"); + return false; + } + + if (!check_passwd()) + return false; + + command = find_in_path(argv[0], plugin_state.envp); + if (command == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "%s: command not found\n", argv[0]); + return false; + } + + /* If "sudo vi" is run, auto-convert to sudoedit. */ + if (strcmp(command, _PATH_VI) == 0) + use_sudoedit = true; + + if (use_sudoedit) { + /* Rebuild argv using editor */ + free(command); + command = find_editor(argc - 1, argv + 1, argv_out); + if (command == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "unable to find valid editor\n"); + return -1; + } + use_sudoedit = true; + } else { + /* No changes needd to argv */ + *argv_out = (char **)argv; + } + + /* No changes to envp */ + *user_env_out = plugin_state.envp; + + /* Setup command info. */ + *command_info_out = build_command_info(command); + free(command); + if (*command_info_out == NULL) { + sudo_log(SUDO_CONV_ERROR_MSG, "out of memory\n"); + return -1; + } + + return true; +} + +static int +policy_list(int argc, char * const argv[], int verbose, const char *list_user, + const char **errstr) +{ + /* + * List user's capabilities. + */ + sudo_log(SUDO_CONV_INFO_MSG, "Validated users may run any command\n"); + return true; +} + +static int +policy_version(int verbose) +{ + sudo_log(SUDO_CONV_INFO_MSG, "Sample policy plugin version %s\n", + 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\n", strerror(error)); + } else { + if (WIFEXITED(exit_status)) { + sudo_log(SUDO_CONV_INFO_MSG, "Command exited with status %d\n", + WEXITSTATUS(exit_status)); + } else if (WIFSIGNALED(exit_status)) { + sudo_log(SUDO_CONV_INFO_MSG, "Command killed by signal %d\n", + WTERMSIG(exit_status)); + } + } +} + +static int +io_open(unsigned int version, sudo_conv_t conversation, + sudo_printf_t sudo_plugin_printf, char * const settings[], + char * const user_info[], char * const command_info[], + int argc, char * const argv[], char * const user_env[], char * const args[], + const char **errstr) +{ + int fd; + char path[PATH_MAX]; + + if (!sudo_conv) + sudo_conv = conversation; + if (!sudo_log) + sudo_log = sudo_plugin_printf; + + /* Open input and output files. */ + snprintf(path, sizeof(path), "/var/tmp/sample-%u.output", + (unsigned int)getpid()); + fd = open(path, O_WRONLY|O_CREAT|O_EXCL, 0644); + if (fd == -1) + return false; + output = fdopen(fd, "w"); + + snprintf(path, sizeof(path), "/var/tmp/sample-%u.input", + (unsigned int)getpid()); + fd = open(path, O_WRONLY|O_CREAT|O_EXCL, 0644); + if (fd == -1) + return false; + input = fdopen(fd, "w"); + + return true; +} + +static void +io_close(int exit_status, int error) +{ + fclose(input); + fclose(output); +} + +static int +io_version(int verbose) +{ + sudo_log(SUDO_CONV_INFO_MSG, "Sample I/O plugin version %s\n", + PACKAGE_VERSION); + return true; +} + +static int +io_log_input(const char *buf, unsigned int len, const char **errstr) +{ + ignore_result(fwrite(buf, len, 1, input)); + return true; +} + +static int +io_log_output(const char *buf, unsigned int len, const char **errstr) +{ + const char *cp, *ep; + bool ret = true; + + ignore_result(fwrite(buf, len, 1, output)); + /* + * If we find the string "honk!" in the buffer, reject it. + * In practice we'd want to be able to detect the word + * broken across two buffers. + */ + for (cp = buf, ep = buf + len; cp < ep; cp++) { + if (cp + 5 < ep && memcmp(cp, "honk!", 5) == 0) { + ret = false; + break; + } + } + return ret; +} + +sudo_dso_public 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 */ + NULL, /* init_session */ + NULL, /* register_hooks */ + NULL, /* deregister_hooks */ + NULL /* event_alloc() filled in by sudo */ +}; + +/* + * Note: This plugin does not differentiate between tty and pipe I/O. + * It all gets logged to the same file. + */ +sudo_dso_public struct io_plugin sample_io = { + SUDO_IO_PLUGIN, + SUDO_API_VERSION, + io_open, + io_close, + io_version, + io_log_input, /* tty input */ + io_log_output, /* tty output */ + io_log_input, /* command stdin if not tty */ + io_log_output, /* command stdout if not tty */ + io_log_output, /* command stderr if not tty */ + NULL, /* register_hooks */ + NULL, /* deregister_hooks */ + NULL, /* change_winsize */ + NULL, /* log_suspend */ + NULL /* event_alloc() filled in by sudo */ +}; 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