/*

 * SPDX-License-Identifier: ISC

 *

 * Copyright (c) 2012, 2014-2022 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.

 */

#include <config.h>

#include <sys/stat.h>

#include <errno.h>

#include <fcntl.h>

#include <string.h>

#include <unistd.h>

#include <sudo_compat.h>

#include <sudo_util.h>

#include <sudo_debug.h>

/*

 * Verify that path is the right type and not writable by other users.

 */

static int

sudo_check_secure(struct stat *sb, unsigned int type, uid_t uid, gid_t gid)

{

    int ret = SUDO_PATH_SECURE;

    debug_decl(sudo_check_secure, SUDO_DEBUG_UTIL);

    if ((sb->st_mode & S_IFMT) != type) {

  ret = SUDO_PATH_BAD_TYPE;

    } else if (uid != (uid_t)-1 && sb->st_uid != uid) {

  ret = SUDO_PATH_WRONG_OWNER;

    } else if (sb->st_mode & S_IWOTH) {

  ret = SUDO_PATH_WORLD_WRITABLE;

    } else if (ISSET(sb->st_mode, S_IWGRP) &&

  (gid == (gid_t)-1 || sb->st_gid != gid)) {

  ret = SUDO_PATH_GROUP_WRITABLE;

    }

    debug_return_int(ret);

}

/*

 * Verify that path is the right type and not writable by other users.

 */

static int

sudo_secure_path(const char *path, unsigned int type, uid_t uid, gid_t gid,

     struct stat *sb)

{

    int ret = SUDO_PATH_MISSING;

    struct stat stat_buf;

    debug_decl(sudo_secure_path, SUDO_DEBUG_UTIL);

    if (sb == NULL)

  sb = &stat_buf;

    if (path != NULL && stat(path, sb) == 0)

  ret = sudo_check_secure(sb, type, uid, gid);

    debug_return_int(ret);

}

/*

 * Verify that path is a regular file and not writable by other users.

 * Not currently used.

 */

int

sudo_secure_file_v1(const char *path, uid_t uid, gid_t gid, struct stat *sb)

{

    return sudo_secure_path(path, S_IFREG, uid, gid, sb);

}

/*

 * Verify that path is a directory and not writable by other users.

 */

int

sudo_secure_dir_v1(const char *path, uid_t uid, gid_t gid, struct stat *sb)

{

    return sudo_secure_path(path, S_IFDIR, uid, gid, sb);

}

/*

 * Verify that fd matches type and not writable by other users.

 */

int

sudo_secure_fd_v1(int fd, unsigned int type, uid_t uid, gid_t gid,

    struct stat *sb)

{

    int ret = SUDO_PATH_MISSING;

    debug_decl(sudo_secure_fd, SUDO_DEBUG_UTIL);

    if (fd != -1 && fstat(fd, sb) == 0)

  ret = sudo_check_secure(sb, type, uid, gid);

    debug_return_int(ret);

}

/*

 * Open path read-only as long as it is not writable by other users.

 * Returns an open file descriptor on success, else -1.

 * Sets error to SUDO_PATH_SECURE on success, and a value < 0 on failure.

 */

static int

sudo_secure_open(const char *path, unsigned int type, uid_t uid, gid_t gid,

    struct stat *sb, int *error)

{

    struct stat stat_buf;

    int fd, flags = O_RDONLY|O_NONBLOCK;

    debug_decl(sudo_secure_open, SUDO_DEBUG_UTIL);

    if (sb == NULL)

  sb = &stat_buf;

    if (type == S_IFDIR)

  flags |= O_DIRECTORY;

    fd = open(path, flags);

    if (fd == -1 || fstat(fd, sb) != 0) {

  if (fd != -1)

      close(fd);

  *error = SUDO_PATH_MISSING;

  debug_return_int(-1);

    }

    *error = sudo_check_secure(sb, type, uid, gid);

    if (*error == SUDO_PATH_SECURE) {

  (void)fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);

    } else {

  /* Not secure, caller can check error flag. */

  close(fd);

  fd = -1;

    }

    debug_return_int(fd);

}

int

sudo_secure_open_file_v1(const char *path, uid_t uid, gid_t gid,

    struct stat *sb, int *error)

{

    return sudo_secure_open(path, S_IFREG, uid, gid, sb, error);

}

int

sudo_secure_open_dir_v1(const char *path, uid_t uid, gid_t gid,

    struct stat *sb, int *error)

{

    return sudo_secure_open(path, S_IFDIR, uid, gid, sb, error);

}

/*

 * Open the first file found in a colon-separated list of paths.

 * Subsequent files in the path are only attempted if the

 * previous file does not exist.  Errors other than ENOENT are

 * considered fatal and will stop processing the path.

 * Sets name based on the last file it tried to open, even on error.

 */

int

sudo_open_conf_path_v1(const char *path, char *name, size_t namesize,

    int (*fn)(const char *, int))

{

    const char *cp, *ep, *path_end;

    int fd = -1;

    debug_decl(sudo_open_conf_path, SUDO_DEBUG_UTIL);

    path_end = path + strlen(path);

    for (cp = sudo_strsplit(path, path_end, ":", &ep);

  cp != NULL; cp = sudo_strsplit(NULL, path_end, ":", &ep)) {

  const size_t len = (size_t)(ep - cp);

  if (len >= namesize) {

      /* We always set name, even on error. */

      memcpy(name, cp, namesize - 1);

      name[namesize - 1] = '\0';

      errno = ENAMETOOLONG;

      break;

  }

  memcpy(name, cp, len);

  name[len] = '\0';

  fd = fn ?

      fn(name, O_RDONLY|O_NONBLOCK) : open(name, O_RDONLY|O_NONBLOCK);

  if (fd != -1) {

      (void)fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);

      break;

  }

  if (errno != ENOENT)

      break;

    }

    debug_return_int(fd);

}