/*
 * eset_rtp (ESET Real-time file system protection module)
 * Copyright (C) 1992-2023 ESET, spol. s r.o.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * In case of any questions, you can contact us at ESET, spol. s r.o., Einsteinova 24, 851 01 Bratislava, Slovakia.
 */

#include <linux/file.h>
#include <linux/namei.h>

#include "ertp_event_check.h"
#include "ertp_ftrace_utils.h"
#include "ertp_handlers_mmap.h"
#include "ertp_logs.h"
#include "ertp_path.h"

#ifdef ERTP_KERNEL_USES_SYSCALL_WRAPPER

sys_regs_t ertp_original_native_64_mmap;

#else

sys_mmap_t ertp_original_native_64_mmap;

#endif

#ifdef ERTP_KERNEL_USES_SYSCALL_WRAPPER

asmlinkage long notrace ertp_handler_native_64_mmap(struct pt_regs *regs) {
  unsigned long prot = ERTP_SYSCALL64_ARG2(unsigned long, regs);
  unsigned long flags = ERTP_SYSCALL64_ARG3(unsigned long, regs);
  unsigned long fd = ERTP_SYSCALL64_ARG4(unsigned long, regs);

  long ret = 0;
  struct file *file;

  if ((flags & MAP_ANONYMOUS) || (fd == -1) || !(prot & PROT_EXEC)) {
    goto end;
  }

  file = fget(fd);
  if (!file) {
    ret = -EBADF;
    goto error;
  }

  ret = ertp_check_exec(file);
  fput(file);

  if (unlikely(ret == ERTP_DENIED)) {
    ertp_pr_log(ERTP_LOG_EXEC,
                "mmap failed or was denied by scanner (errno: %ld)", ret);
    ret = -EPERM;
    goto error;
  }

end:
  ret = ertp_original_native_64_mmap(regs);

error:
  ertp_handler_end();
  return ret;
}

#else

asmlinkage long notrace ertp_handler_native_64_mmap(
    unsigned long addr, unsigned long len, unsigned long prot,
    unsigned long flags, unsigned long fd, off_t pgoff) {
  long ret = 0;
  struct file *file;

  if ((flags & MAP_ANONYMOUS) || (fd == -1) || !(prot & PROT_EXEC)) {
    goto end;
  }

  file = fget(fd);
  if (!file) {
    ret = -EBADF;
    goto error;
  }

  ret = ertp_check_exec(file);
  fput(file);

  if (unlikely(ret == ERTP_DENIED)) {
    ertp_pr_log(ERTP_LOG_EXEC,
                "mmap failed or was denied by scanner (errno: %ld)", ret);
    ret = -EPERM;
    goto error;
  }

end:
  ret = ertp_original_native_64_mmap(addr, len, prot, flags, fd, pgoff);

error:
  ertp_handler_end();
  return ret;
}

#endif