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_SOLARIS || SANITIZER_HAIKU
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 trampoline) {
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: 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: 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 == trampoline)
54 addr = nullptr;
55 }
56 return addr;
57}
58
59bool InterceptFunction(const char *name, uptr *ptr_to_real, uptr func,
60 uptr trampoline) {
61 void *addr = GetFuncAddr(name, trampoline);
62 *ptr_to_real = (uptr)addr;
63 return addr && (func == trampoline);
64}
65
66// dlvsym is a GNU extension supported by some other platforms.
67#if SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
68static void *GetFuncAddr(const char *name, const char *ver) {
69 return dlvsym(RTLD_NEXT, name: name, version: ver);
70}
71
72bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
73 uptr func, uptr trampoline) {
74 void *addr = GetFuncAddr(name, ver);
75 *ptr_to_real = (uptr)addr;
76 return addr && (func == trampoline);
77}
78# endif // SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
79
80} // namespace __interception
81
82#endif // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
83 // SANITIZER_SOLARIS || SANITIZER_HAIKU
84