/*

 * SPDX-License-Identifier: ISC

 *

 * Copyright (c) 1996, 1998-2005, 2007-2020

 *  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.

 *

 * Sponsored in part by the Defense Advanced Research Projects

 * Agency (DARPA) and Air Force Research Laboratory, Air Force

 * Materiel Command, USAF, under agreement number F39502-99-1-0512.

 */

/*

 * 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 <errno.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <fcntl.h>

#include <unistd.h>

#include <sudoers.h>

#include <sudo_digest.h>

#include <gram.h>

int

digest_matches(int fd, const char *path, const char *runchroot,

    const struct command_digest_list *digests)

{

    unsigned int digest_type = SUDO_DIGEST_INVALID;

    unsigned char *file_digest = NULL;

    unsigned char *sudoers_digest = NULL;

    struct command_digest *digest;

    char pathbuf[PATH_MAX];

    size_t digest_len;

    int matched = DENY;

    int fd2 = -1;

    debug_decl(digest_matches, SUDOERS_DEBUG_MATCH);

    if (TAILQ_EMPTY(digests)) {

  /* No digest, no problem. */

  debug_return_int(ALLOW);

    }

    if (fd == -1) {

  fd2 = open(path, O_RDONLY|O_NONBLOCK);

  if (fd2 == -1) {

      /* No file, no match. */

      goto done;

  }

  fd = fd2;

    }

    if (runchroot != NULL) {

  /* XXX - handle symlinks and '..' in path outside chroot */

  const int len =

      snprintf(pathbuf, sizeof(pathbuf), "%s%s", runchroot, path);

  if (len >= ssizeof(pathbuf)) {

      errno = ENAMETOOLONG;

      debug_return_bool(false);

  }

  path = pathbuf;

    }

    TAILQ_FOREACH(digest, digests, entries) {

  /* Compute file digest if needed. */

  if (digest->digest_type != digest_type) {

      free(file_digest);

      file_digest = sudo_filedigest(fd, path, digest->digest_type,

    &digest_len);

      if (lseek(fd, (off_t)0, SEEK_SET) == -1) {

    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO,

        "unable to rewind digest fd");

      }

      digest_type = digest->digest_type;

  }

  if (file_digest == NULL) {

      /* Warning (if any) printed by sudo_filedigest() */

      goto done;

  }

  /* Convert the command digest from ascii to binary. */

  if ((sudoers_digest = malloc(digest_len)) == NULL) {

      sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));

      goto done;

  }

  if (strlen(digest->digest_str) == digest_len * 2) {

      /* Convert ascii hex to binary. */

      size_t i;

      for (i = 0; i < digest_len; i++) {

    const int h = sudo_hexchar(&digest->digest_str[2 * i]);

    if (h == -1)

        goto bad_format;

    sudoers_digest[i] = (unsigned char)h;

      }

  } else {

      /* Convert base64 to binary. */

      size_t len = base64_decode(digest->digest_str, sudoers_digest, digest_len);

      if (len == (size_t)-1)

    goto bad_format;

      if (len != digest_len) {

    sudo_warnx(

        U_("digest for %s (%s) bad length %zu, expected %zu"),

        path, digest->digest_str, len, digest_len);

    goto done;

      }

  }

  if (memcmp(file_digest, sudoers_digest, digest_len) == 0) {

      matched = ALLOW;

      break;

  }

  sudo_debug_printf(SUDO_DEBUG_DIAG|SUDO_DEBUG_LINENO,

      "%s digest mismatch for %s, expecting %s",

      digest_type_to_name(digest->digest_type), path, digest->digest_str);

  free(sudoers_digest);

  sudoers_digest = NULL;

    }

    goto done;

bad_format:

    sudo_warnx(U_("digest for %s (%s) is not in %s form"), path,

  digest->digest_str, digest_type_to_name(digest->digest_type));

done:

    if (fd2 != -1)

  close(fd2);

    free(sudoers_digest);

    free(file_digest);

    debug_return_int(matched);

}