1 //===-- dfsan_interceptors.cpp --------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is a part of DataFlowSanitizer.
10 //
11 // Interceptors for standard library functions.
12 //===----------------------------------------------------------------------===//
13 
14 #include <sys/syscall.h>
15 #include <unistd.h>
16 
17 #include "dfsan/dfsan.h"
18 #include "interception/interception.h"
19 #include "sanitizer_common/sanitizer_common.h"
20 
21 using namespace __sanitizer;
22 
23 namespace {
24 
25 bool interceptors_initialized;
26 
27 }  // namespace
28 
29 INTERCEPTOR(void *, mmap, void *addr, SIZE_T length, int prot, int flags,
30             int fd, OFF_T offset) {
31   void *res;
32 
33   // interceptors_initialized is set to true during preinit_array, when we're
34   // single-threaded.  So we don't need to worry about accessing it atomically.
35   if (!interceptors_initialized)
36     res = (void *)syscall(__NR_mmap, addr, length, prot, flags, fd, offset);
37   else
38     res = REAL(mmap)(addr, length, prot, flags, fd, offset);
39 
40   if (res != (void *)-1)
41     dfsan_set_label(0, res, RoundUpTo(length, GetPageSizeCached()));
42   return res;
43 }
44 
45 INTERCEPTOR(void *, mmap64, void *addr, SIZE_T length, int prot, int flags,
46             int fd, OFF64_T offset) {
47   void *res = REAL(mmap64)(addr, length, prot, flags, fd, offset);
48   if (res != (void *)-1)
49     dfsan_set_label(0, res, RoundUpTo(length, GetPageSizeCached()));
50   return res;
51 }
52 
53 INTERCEPTOR(int, munmap, void *addr, SIZE_T length) {
54   int res = REAL(munmap)(addr, length);
55   if (res != -1)
56     dfsan_set_label(0, addr, RoundUpTo(length, GetPageSizeCached()));
57   return res;
58 }
59 
60 namespace __dfsan {
61 void InitializeInterceptors() {
62   CHECK(!interceptors_initialized);
63 
64   INTERCEPT_FUNCTION(mmap);
65   INTERCEPT_FUNCTION(mmap64);
66   INTERCEPT_FUNCTION(munmap);
67 
68   interceptors_initialized = true;
69 }
70 }  // namespace __dfsan
71