restrict_process_capsicum.c

/* Copyright (c) 2019-2022, 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/time.h>
#include <sys/types.h>
#include <unistd.h>

#include <sys/procctl.h>

#include <errno.h>

int disable_setuid_subprocess(void) {
#ifdef PROC_NO_NEW_PRIVS_CTL
    int data = PROC_NO_NEW_PRIVS_ENABLE;
    return procctl(P_PID, 0, PROC_NO_NEW_PRIVS_CTL, &data);
#else
    return 0;
#endif
}

int restrict_process_signal_on_supervisor_exit(void) { return 0; }

int restrict_process_init(void) { return 0; }

int restrict_process(void) {
  struct rlimit rl = {0};
  cap_rights_t policy_read;
  cap_rights_t policy_write;

  if (setrlimit(RLIMIT_NPROC, &rl) < 0)
    return -1;

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

  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();
}

int restrict_process_wait(int fdp) {
  struct rlimit rl = {0};
  cap_rights_t policy_read;
  cap_rights_t policy_write;
  cap_rights_t policy_rw;

  if (setrlimit(RLIMIT_NPROC, &rl) < 0)
    return -1;

  if (cap_enter() == -1)
    return -1;

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

  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;

  if (cap_rights_limit(fdp, &policy_rw) < 0)
    return -1;

  return 0;
}
#endif