syscall.c

/*
   Kafel - syscalls
   -----------------------------------------

   Copyright 2016 Google Inc. All Rights Reserved.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

*/

#include "syscall.h"

#include <stdlib.h>
#include <string.h>

#include <linux/audit.h>

#include "common.h"

#define SYSCALL_LIST_DECL(arch)                                 \
  extern const struct syscall_descriptor arch##_syscall_list[]; \
  extern const size_t arch##_syscall_list_size;

#define SYSCALL_LIST(audit_arch, arch) \
  { audit_arch, arch##_syscall_list, &arch##_syscall_list_size }

SYSCALL_LIST_DECL(arm)
SYSCALL_LIST_DECL(amd64)

const struct syscall_list syscall_lists[] = {
    SYSCALL_LIST(AUDIT_ARCH_ARM, arm), SYSCALL_LIST(AUDIT_ARCH_X86_64, amd64)};

struct syscall_descriptor* syscall_custom(uint32_t nr) {
  struct syscall_descriptor* rv = calloc(1, sizeof(*rv));
  rv->nr = nr;
  rv->is_custom = true;
  return rv;
}

const struct syscall_list* syscalls_lookup(uint32_t arch) {
  for (size_t i = 0; i < sizeof(syscall_lists) / sizeof(syscall_lists[0]);
       ++i) {
    if (syscall_lists[i].arch == arch) {
      return &syscall_lists[i];
    }
  }
  return NULL;
}

const struct syscall_descriptor* syscall_lookup(const struct syscall_list* list,
                                                const char* name) {
  ASSERT(list != NULL);
  ASSERT(name != NULL);
  /* TODO use binary search if syscalls can be guaranteed to be
   *  sorted alphabetically
   */
  for (size_t i = 0; i < *list->size; ++i) {
    if (strcmp(name, list->syscalls[i].name) == 0) {
      return &list->syscalls[i];
    }
  }
  return NULL;
}

void syscall_descriptor_destroy(struct syscall_descriptor** desc) {
  ASSERT(desc != NULL);
  ASSERT((*desc) != NULL);

  if ((*desc)->is_custom) {
    free(*desc);
  }
  (*desc) = NULL;
}