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