libsanitizer/interception/interception_linux.cpp

   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
  18
  19 #include <dlfcn.h>   // for dlsym() and dlvsym()
  20
  21 namespace __interception {
  22
  23 #if SANITIZER_NETBSD
  24 static 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
  36 static 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
  59 bool 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 // dlvsym is a GNU extension supported by some other platforms.
  67 #if SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
  68 static void *GetFuncAddr(const char *name, const char *ver) {
  69   return dlvsym(RTLD_NEXT, name, ver);
  70 }
  71
  72 bool 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_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
  79
  80 }  // namespace __interception
  81
  82 #endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
  83         // SANITIZER_SOLARIS