restrict_process_capsicum.c

/* Copyright (c) 2020-2023, Michael Santos <michael.santos@gmail.com>
 *
 * Permission to use, copy, modify, and/or 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 "restrict_process.h"
#ifdef RESTRICT_PROCESS_capsicum
#include <sys/capsicum.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#include <errno.h>

int restrict_process_init() {
  struct rlimit rl = {0};
  struct stat sb;

  if (fstat(STDOUT_FILENO, &sb) < 0)
    return -1;

  if (!S_ISREG(sb.st_mode)) {
    if (setrlimit(RLIMIT_FSIZE, &rl) < 0)
      return -1;
  }

  return setrlimit(RLIMIT_NPROC, &rl);
}

int restrict_process_stdin() {
  cap_rights_t policy_read;
  cap_rights_t policy_write;

  closefrom(STDERR_FILENO + 1);

  (void)cap_rights_init(&policy_read, CAP_READ, CAP_EVENT);
  (void)cap_rights_init(&policy_write, CAP_WRITE, CAP_READ);

  if (cap_rights_limit(STDIN_FILENO, &policy_read) < 0)
    return -1;

  if (cap_rights_limit(STDOUT_FILENO, &policy_write) < 0)
    return -1;

  if (cap_rights_limit(STDERR_FILENO, &policy_write) < 0)
    return -1;

  return cap_enter();
}
#endif