1*ff6d591cSmrg //===-- interception_linux.cpp ----------------------------------*- C++ -*-===//
2*ff6d591cSmrg //
3*ff6d591cSmrg // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*ff6d591cSmrg // See https://llvm.org/LICENSE.txt for license information.
5*ff6d591cSmrg // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*ff6d591cSmrg //
7*ff6d591cSmrg //===----------------------------------------------------------------------===//
8*ff6d591cSmrg //
9*ff6d591cSmrg // This file is a part of AddressSanitizer, an address sanity checker.
10*ff6d591cSmrg //
11*ff6d591cSmrg // Linux-specific interception methods.
12*ff6d591cSmrg //===----------------------------------------------------------------------===//
13*ff6d591cSmrg
14*ff6d591cSmrg #include "interception.h"
15*ff6d591cSmrg
16*ff6d591cSmrg #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
17*ff6d591cSmrg SANITIZER_SOLARIS
18*ff6d591cSmrg
19*ff6d591cSmrg #include <dlfcn.h> // for dlsym() and dlvsym()
20*ff6d591cSmrg
21*ff6d591cSmrg namespace __interception {
22*ff6d591cSmrg
23*ff6d591cSmrg #if SANITIZER_NETBSD
StrCmp(const char * s1,const char * s2)24*ff6d591cSmrg static int StrCmp(const char *s1, const char *s2) {
25*ff6d591cSmrg while (true) {
26*ff6d591cSmrg if (*s1 != *s2)
27*ff6d591cSmrg return false;
28*ff6d591cSmrg if (*s1 == 0)
29*ff6d591cSmrg return true;
30*ff6d591cSmrg s1++;
31*ff6d591cSmrg s2++;
32*ff6d591cSmrg }
33*ff6d591cSmrg }
34*ff6d591cSmrg #endif
35*ff6d591cSmrg
GetFuncAddr(const char * name,uptr wrapper_addr)36*ff6d591cSmrg static void *GetFuncAddr(const char *name, uptr wrapper_addr) {
37*ff6d591cSmrg #if SANITIZER_NETBSD
38*ff6d591cSmrg // FIXME: Find a better way to handle renames
39*ff6d591cSmrg if (StrCmp(name, "sigaction"))
40*ff6d591cSmrg name = "__sigaction14";
41*ff6d591cSmrg #endif
42*ff6d591cSmrg void *addr = dlsym(RTLD_NEXT, name);
43*ff6d591cSmrg if (!addr) {
44*ff6d591cSmrg // If the lookup using RTLD_NEXT failed, the sanitizer runtime library is
45*ff6d591cSmrg // later in the library search order than the DSO that we are trying to
46*ff6d591cSmrg // intercept, which means that we cannot intercept this function. We still
47*ff6d591cSmrg // want the address of the real definition, though, so look it up using
48*ff6d591cSmrg // RTLD_DEFAULT.
49*ff6d591cSmrg addr = dlsym(RTLD_DEFAULT, name);
50*ff6d591cSmrg
51*ff6d591cSmrg // In case `name' is not loaded, dlsym ends up finding the actual wrapper.
52*ff6d591cSmrg // We don't want to intercept the wrapper and have it point to itself.
53*ff6d591cSmrg if ((uptr)addr == wrapper_addr)
54*ff6d591cSmrg addr = nullptr;
55*ff6d591cSmrg }
56*ff6d591cSmrg return addr;
57*ff6d591cSmrg }
58*ff6d591cSmrg
InterceptFunction(const char * name,uptr * ptr_to_real,uptr func,uptr wrapper)59*ff6d591cSmrg bool InterceptFunction(const char *name, uptr *ptr_to_real, uptr func,
60*ff6d591cSmrg uptr wrapper) {
61*ff6d591cSmrg void *addr = GetFuncAddr(name, wrapper);
62*ff6d591cSmrg *ptr_to_real = (uptr)addr;
63*ff6d591cSmrg return addr && (func == wrapper);
64*ff6d591cSmrg }
65*ff6d591cSmrg
66*ff6d591cSmrg // dlvsym is a GNU extension supported by some other platforms.
67*ff6d591cSmrg #if SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
GetFuncAddr(const char * name,const char * ver)68*ff6d591cSmrg static void *GetFuncAddr(const char *name, const char *ver) {
69*ff6d591cSmrg return dlvsym(RTLD_NEXT, name, ver);
70*ff6d591cSmrg }
71*ff6d591cSmrg
InterceptFunction(const char * name,const char * ver,uptr * ptr_to_real,uptr func,uptr wrapper)72*ff6d591cSmrg bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
73*ff6d591cSmrg uptr func, uptr wrapper) {
74*ff6d591cSmrg void *addr = GetFuncAddr(name, ver);
75*ff6d591cSmrg *ptr_to_real = (uptr)addr;
76*ff6d591cSmrg return addr && (func == wrapper);
77*ff6d591cSmrg }
78*ff6d591cSmrg #endif // SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
79*ff6d591cSmrg
80*ff6d591cSmrg } // namespace __interception
81*ff6d591cSmrg
82*ff6d591cSmrg #endif // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
83*ff6d591cSmrg // SANITIZER_SOLARIS
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