1 //===-- interception_linux.cc -----------------------------------*- C++ -*-===//
3 // This file is distributed under the University of Illinois Open Source
4 // License. See LICENSE.TXT for details.
6 //===----------------------------------------------------------------------===//
8 // This file is a part of AddressSanitizer, an address sanity checker.
10 // Windows-specific interception methods.
11 //===----------------------------------------------------------------------===//
15 #include "interception.h"
18 namespace __interception
{
20 // FIXME: internal_str* and internal_mem* functions should be moved from the
21 // ASan sources into interception/.
23 static void _memset(void *p
, int value
, size_t sz
) {
24 for (size_t i
= 0; i
< sz
; ++i
)
25 ((char*)p
)[i
] = (char)value
;
28 static void _memcpy(void *dst
, void *src
, size_t sz
) {
29 char *dst_c
= (char*)dst
,
31 for (size_t i
= 0; i
< sz
; ++i
)
35 static void WriteJumpInstruction(char *jmp_from
, char *to
) {
36 // jmp XXYYZZWW = E9 WW ZZ YY XX, where XXYYZZWW is an offset fromt jmp_from
37 // to the next instruction to the destination.
38 ptrdiff_t offset
= to
- jmp_from
- 5;
40 *(ptrdiff_t*)(jmp_from
+ 1) = offset
;
43 static char *GetMemoryForTrampoline(size_t size
) {
44 // Trampolines are allocated from a common pool.
45 const int POOL_SIZE
= 1024;
46 static char *pool
= NULL
;
47 static size_t pool_used
= 0;
49 pool
= (char *)VirtualAlloc(NULL
, POOL_SIZE
, MEM_RESERVE
| MEM_COMMIT
,
50 PAGE_EXECUTE_READWRITE
);
51 // FIXME: Might want to apply PAGE_EXECUTE_READ access after all the
52 // interceptors are in place.
55 _memset(pool
, 0xCC /* int 3 */, POOL_SIZE
);
58 if (pool_used
+ size
> POOL_SIZE
)
61 char *ret
= pool
+ pool_used
;
66 // Returns 0 on error.
67 static size_t RoundUpToInstrBoundary(size_t size
, char *code
) {
69 while (cursor
< size
) {
70 switch (code
[cursor
]) {
71 case '\x51': // push ecx
72 case '\x52': // push edx
73 case '\x53': // push ebx
74 case '\x54': // push esp
75 case '\x55': // push ebp
76 case '\x56': // push esi
77 case '\x57': // push edi
78 case '\x5D': // pop ebp
81 case '\x6A': // 6A XX = push XX
84 case '\xE9': // E9 XX YY ZZ WW = jmp WWZZYYXX
88 switch (*(unsigned short*)(code
+ cursor
)) { // NOLINT
89 case 0xFF8B: // 8B FF = mov edi, edi
90 case 0xEC8B: // 8B EC = mov ebp, esp
91 case 0xC033: // 33 C0 = xor eax, eax
94 case 0x458B: // 8B 45 XX = mov eax, dword ptr [ebp+XXh]
95 case 0x5D8B: // 8B 5D XX = mov ebx, dword ptr [ebp+XXh]
96 case 0xEC83: // 83 EC XX = sub esp, XX
97 case 0x75FF: // FF 75 XX = push dword ptr [ebp+XXh]
100 case 0xC1F7: // F7 C1 XX YY ZZ WW = test ecx, WWZZYYXX
101 case 0x25FF: // FF 25 XX YY ZZ WW = jmp dword ptr ds:[WWZZYYXX]
104 case 0x3D83: // 83 3D XX YY ZZ WW TT = cmp TT, WWZZYYXX
108 switch (0x00FFFFFF & *(unsigned int*)(code
+ cursor
)) {
109 case 0x24448A: // 8A 44 24 XX = mov eal, dword ptr [esp+XXh]
110 case 0x24448B: // 8B 44 24 XX = mov eax, dword ptr [esp+XXh]
111 case 0x244C8B: // 8B 4C 24 XX = mov ecx, dword ptr [esp+XXh]
112 case 0x24548B: // 8B 54 24 XX = mov edx, dword ptr [esp+XXh]
113 case 0x24748B: // 8B 74 24 XX = mov esi, dword ptr [esp+XXh]
114 case 0x247C8B: // 8B 7C 24 XX = mov edi, dword ptr [esp+XXh]
119 // Unknown instruction!
120 // FIXME: Unknown instruction failures might happen when we add a new
121 // interceptor or a new compiler version. In either case, they should result
122 // in visible and readable error messages. However, merely calling abort()
123 // leads to an infinite recursion in CheckFailed.
124 // Do we have a good way to abort with an error message here?
132 bool OverrideFunction(uptr old_func
, uptr new_func
, uptr
*orig_old_func
) {
134 #error OverrideFunction is not yet supported on x64
136 // Function overriding works basically like this:
137 // We write "jmp <new_func>" (5 bytes) at the beginning of the 'old_func'
139 // We might want to be able to execute the original 'old_func' from the
140 // wrapper, in this case we need to keep the leading 5+ bytes ('head')
141 // of the original code somewhere with a "jmp <old_func+head>".
142 // We call these 'head'+5 bytes of instructions a "trampoline".
143 char *old_bytes
= (char *)old_func
;
145 // We'll need at least 5 bytes for a 'jmp'.
148 // Find out the number of bytes of the instructions we need to copy
149 // to the trampoline and store it in 'head'.
150 head
= RoundUpToInstrBoundary(head
, old_bytes
);
154 // Put the needed instructions into the trampoline bytes.
155 char *trampoline
= GetMemoryForTrampoline(head
+ 5);
158 _memcpy(trampoline
, old_bytes
, head
);
159 WriteJumpInstruction(trampoline
+ head
, old_bytes
+ head
);
160 *orig_old_func
= (uptr
)trampoline
;
163 // Now put the "jmp <new_func>" instruction at the original code location.
164 // We should preserve the EXECUTE flag as some of our own code might be
165 // located in the same page (sic!). FIXME: might consider putting the
166 // __interception code into a separate section or something?
167 DWORD old_prot
, unused_prot
;
168 if (!VirtualProtect((void *)old_bytes
, head
, PAGE_EXECUTE_READWRITE
,
172 WriteJumpInstruction(old_bytes
, (char *)new_func
);
173 _memset(old_bytes
+ 5, 0xCC /* int 3 */, head
- 5);
175 // Restore the original permissions.
176 if (!VirtualProtect((void *)old_bytes
, head
, old_prot
, &unused_prot
))
177 return false; // not clear if this failure bothers us.
182 static const void **InterestingDLLsAvailable() {
183 const char *InterestingDLLs
[] = { "kernel32.dll", "msvcr120.dll", NULL
};
184 static void *result
[ARRAY_SIZE(InterestingDLLs
)] = { 0 };
186 for (size_t i
= 0, j
= 0; InterestingDLLs
[i
]; ++i
) {
187 if (HMODULE h
= GetModuleHandleA(InterestingDLLs
[i
]))
188 result
[j
++] = (void *)h
;
191 return (const void **)&result
[0];
194 static bool GetFunctionAddressInDLLs(const char *func_name
, uptr
*func_addr
) {
196 const void **DLLs
= InterestingDLLsAvailable();
197 for (size_t i
= 0; *func_addr
== 0 && DLLs
[i
]; ++i
)
198 *func_addr
= (uptr
)GetProcAddress((HMODULE
)DLLs
[i
], func_name
);
199 return (*func_addr
!= 0);
202 bool OverrideFunction(const char *name
, uptr new_func
, uptr
*orig_old_func
) {
204 if (!GetFunctionAddressInDLLs(name
, &orig_func
))
206 return OverrideFunction(orig_func
, new_func
, orig_old_func
);
209 } // namespace __interception