interception_linux.cpp revision 360784 
1//===-- interception_linux.cpp ----------------------------------*- C++ -*-===//
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 AddressSanitizer, an address sanity checker.
10//
11// Linux-specific interception methods.
12//===----------------------------------------------------------------------===//
13
14#include "interception.h"
15
16#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
17    SANITIZER_OPENBSD || SANITIZER_SOLARIS
18
19#include <dlfcn.h>   // for dlsym() and dlvsym()
20
21namespace __interception {
22
23#if SANITIZER_NETBSD
24static int StrCmp(const char *s1, const char *s2) {
25  while (true) {
26    if (*s1 != *s2)
27      return false;
28    if (*s1 == 0)
29      return true;
30    s1++;
31    s2++;
32  }
33}
34#endif
35
36static void *GetFuncAddr(const char *name, uptr wrapper_addr) {
37#if SANITIZER_NETBSD
38  // FIXME: Find a better way to handle renames
39  if (StrCmp(name, "sigaction"))
40    name = "__sigaction14";
41#endif
42  void *addr = dlsym(RTLD_NEXT, name);
43  if (!addr) {
44    // If the lookup using RTLD_NEXT failed, the sanitizer runtime library is
45    // later in the library search order than the DSO that we are trying to
46    // intercept, which means that we cannot intercept this function. We still
47    // want the address of the real definition, though, so look it up using
48    // RTLD_DEFAULT.
49    addr = dlsym(RTLD_DEFAULT, name);
50
51    // In case `name' is not loaded, dlsym ends up finding the actual wrapper.
52    // We don't want to intercept the wrapper and have it point to itself.
53    if ((uptr)addr == wrapper_addr)
54      addr = nullptr;
55  }
56  return addr;
57}
58
59bool InterceptFunction(const char *name, uptr *ptr_to_real, uptr func,
60                       uptr wrapper) {
61  void *addr = GetFuncAddr(name, wrapper);
62  *ptr_to_real = (uptr)addr;
63  return addr && (func == wrapper);
64}
65
66// Android and Solaris do not have dlvsym
67#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS && !SANITIZER_OPENBSD
68static void *GetFuncAddr(const char *name, const char *ver) {
69  return dlvsym(RTLD_NEXT, name, ver);
70}
71
72bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
73                       uptr func, uptr wrapper) {
74  void *addr = GetFuncAddr(name, ver);
75  *ptr_to_real = (uptr)addr;
76  return addr && (func == wrapper);
77}
78#endif  // !SANITIZER_ANDROID
79
80}  // namespace __interception
81
82#endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
83        // SANITIZER_OPENBSD || SANITIZER_SOLARIS
84