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Root/branches/meklort/i386/boot2/kernel_patcher.c

Source at commit 145 created 13 years 11 months ago.
By meklort, Kernel patcher works now (patched the kernel too late before)
1/*␊
2 * Copyright (c) 2009 Evan Lojewski. All rights reserved.␊
3 *␊
4 */␊
5␊
6#include "libsaio.h"␊
7#include "kernel_patcher.h"␊
8␊
9#define NUM_SYMBOLS␉␉3␊
10␊
11#define SYMBOL_CPUID_SET_INFO␉␉␉␉0␊
12#define SYMBOL_PANIC␉␉␉␉␉␉1␊
13#define SYMBOL_PMCPUEXITHALTTOOFF␉␉␉2␊
14␊
15#define SYMBOL_CPUID_SET_INFO_STRING␉␉"_cpuid_set_info"␊
16#define SYMBOL_PANIC_STRING␉␉␉␉␉"_panic"␊
17#define SYMBOL_PMCPUEXITHALTTOOFF_STRING␉"_pmCPUExitHaltToOff"␊
18␊
19char* kernelSymbols[NUM_SYMBOLS] = {␊
20␉SYMBOL_CPUID_SET_INFO_STRING,␊
21␉SYMBOL_PANIC_STRING,␊
22␉SYMBOL_PMCPUEXITHALTTOOFF_STRING␊
23};␊
24␊
25UInt32 kernelSymbolAddresses[NUM_SYMBOLS] = {␊
26␉0,␊
27␉0,␊
28␉0␊
29};␊
30␊
31␊
32UInt32 textSection = 0;␊
33UInt32 textAddress = 0;␊
34␊
35␊
36extern unsigned long gBinaryAddress;␊
37␊
38␊
39void patch_kernel(void* kernelData)␊
40{␊
41␉switch (locate_symbols((void*)kernelData)) {␊
42␉␉case KERNEL_32:␊
43␉␉␉patch_kernel_32((void*)kernelData);␊
44␉␉␉break;␊
45␉␉␉␊
46␉␉case KERNEL_64:␊
47␉␉default:␊
48␉␉␉patch_kernel_64((void*)kernelData);␊
49␉␉␉break;␊
50␉}␊
51}␊
52␊
53// patches a 64bit kernel.␊
54void patch_kernel_64(void* kernelData)␊
55{␊
56␉// At the moment, the kernel patching code fails when used␊
57␉// in 64bit mode, so we don't patch it. This is due to 32bit vs 64bit␊
58␉// pointers as well as changes in structure sizes␊
59␉printf("Unable to patch 64bit kernel. Please use arch=i386.\n");␊
60}␊
61␊
62␊
63/**␊
64 ** patch_kernel_32␊
65 **␉␉Due to the way the _cpuid_set_info function is writtin, the first instance of _panic is called␊
66 **␉␉␉when an unsupported (read: non apple used cpu) is found. This routine locates that first _panic call␊
67 **␉␉␉and replaces the jump call (0xe8) with no ops (0x90).␊
68 **/␊
69void patch_kernel_32(void* kernelData)␊
70{␊
71␉patch_pmCPUExitHaltToOff(kernelData);␊
72␉patch_cpuid_set_info(kernelData);␊
73␊
74}␊
75␊
76␊
77/**␊
78 **␉␉This functions located the following in the mach_kernel symbol table␊
79 **␉␉␉_panic␊
80 **␉␉␉_cpuid_set_info␊
81 **/␊
82int locate_symbols(void* kernelData)␊
83{␊
84␉UInt16 symbolIndexes[NUM_SYMBOLS];␊
85␊
86␉struct load_command *loadCommand;␊
87␉struct symtab_command *symtableData;␊
88␉struct nlist *symbolEntry;␊
89␉␊
90␉char* symbolString;␊
91␊
92␉UInt32 kernelIndex = 0;␊
93␉kernelIndex += sizeof(struct mach_header);␊
94␉␊
95␉if(((struct mach_header*)kernelData)->magic != MH_MAGIC) return KERNEL_64;␊
96␉␊
97␉␊
98␉//printf("%d load commands beginning at 0x%X\n", (unsigned int)header->ncmds, (unsigned int)kernelIndex);␊
99␉//printf("Commands take up %d bytes\n", header->sizeofcmds);␊
100␉␊
101␉␊
102␉int cmd = 0;␊
103␉while(cmd < ((struct mach_header*)kernelData)->ncmds)␉// TODO: for loop instead␊
104␉{␊
105␉␉cmd++;␊
106␉␉␊
107␉␉loadCommand = kernelData + kernelIndex;␊
108␉␉␊
109␉␉UInt cmdSize = loadCommand->cmdsize;␊
110␉␉␊
111␉␉␊
112␉␉// Locate start of _panic and _cpuid_set_info in the symbol tabe.␊
113␉␉// Load commands should be anded with 0x7FFFFFFF to ignore the␉LC_REQ_DYLD flag␊
114␉␉if((loadCommand->cmd & 0x7FFFFFFF) == LC_SYMTAB)␉␉// We only care about the symtab segment␊
115␉␉{␊
116␉␉␉//printf("Located symtable, length is 0x%X, 0x%X\n", (unsigned int)loadCommand->cmdsize, (unsigned int)sizeof(symtableData));␊
117␉␉␉␊
118␉␉␉symtableData = kernelData + kernelIndex;␊
119␉␉␉kernelIndex += sizeof(struct symtab_command);␊
120␉␉␉␊
121␉␉␉cmdSize -= sizeof(struct symtab_command);␊
122␊
123␉␉␉// Loop through symbol table untill all of the symbols have been found␊
124␉␉␉␊
125␉␉␉symbolString = kernelData + symtableData->stroff; ␊
126␉␉␉␊
127␉␉␉␊
128␉␉␉UInt16 symbolIndex = 0;␊
129␉␉␉UInt8 numSymbolsFound = 0;␊
130␊
131␉␉␉while(symbolIndex < symtableData->nsyms && numSymbolsFound < NUM_SYMBOLS)␉// TODO: for loop␊
132␉␉␉{␊
133␉␉␉␉int i = 0;␊
134␉␉␉␉while(i < NUM_SYMBOLS)␊
135␉␉␉␉{␊
136␉␉␉␉␉if(strcmp(symbolString, kernelSymbols[i]) == 0)␊
137␉␉␉␉␉{␊
138␉␉␉␉␉␉symbolIndexes[i] = symbolIndex;␊
139␉␉␉␉␉␉numSymbolsFound++;␉␉␉␉␊
140␉␉␉␉␉} ␊
141␉␉␉␉␉i++;␊
142␉␉␉␉␉␊
143␉␉␉␉}␊
144␉␉␉␉symbolString += strlen(symbolString) + 1;␊
145␉␉␉␉symbolIndex++;␊
146␉␉␉}␊
147␉␉␉␊
148␉␉␉// loop again␊
149␉␉␉symbolIndex = 0;␊
150␉␉␉numSymbolsFound = 0;␊
151␉␉␉while(symbolIndex < symtableData->nsyms && numSymbolsFound < NUM_SYMBOLS)␉// TODO: for loop␊
152␉␉␉{␊
153␉␉␉␉␊
154␉␉␉␉symbolEntry = kernelData + symtableData->symoff + (symbolIndex * sizeof(struct nlist));␊
155␉␉␉␉␊
156␉␉␉␉int i = 0;␊
157␉␉␉␉while(i < NUM_SYMBOLS)␊
158␉␉␉␉{␊
159␉␉␉␉␉if(symbolIndex == (symbolIndexes[i] - 4))␊
160␉␉␉␉␉{␊
161␉␉␉␉␉␉kernelSymbolAddresses[i] = (UInt32)symbolEntry->n_value;␊
162␉␉␉␉␉␉numSymbolsFound++;␉␉␉␉␊
163␉␉␉␉␉} ␊
164␉␉␉␉␉i++;␊
165␉␉␉␉␉␊
166␉␉␉␉}␊
167␉␉␉␉␊
168␉␉␉␉symbolIndex ++;␊
169␉␉␉}␉␉␉␊
170␉␉// Load commands should be anded with 0x7FFFFFFF to ignore the␉LC_REQ_DYLD flag␊
171␉␉} else if((loadCommand->cmd & 0x7FFFFFFF) == LC_SEGMENT)␉␉// We only care about the __TEXT segment, any other load command can be ignored␊
172␉␉{␊
173␉␉␉␊
174␉␉␉struct segment_command *segCommand;␊
175␉␉␉␊
176␉␉␉segCommand = kernelData + kernelIndex;␊
177␉␉␉␊
178␉␉␉//printf("Segment name is %s\n", segCommand->segname);␊
179␉␉␉␊
180␉␉␉if(strcmp("__TEXT", segCommand->segname) == 0)␊
181␉␉␉{␊
182␉␉␉␉UInt32 sectionIndex;␊
183␉␉␉␉␊
184␉␉␉␉sectionIndex = sizeof(struct segment_command);␊
185␉␉␉␉␊
186␉␉␉␉struct section *sect;␊
187␉␉␉␉␊
188␉␉␉␉while(sectionIndex < segCommand->cmdsize)␊
189␉␉␉␉{␊
190␉␉␉␉␉sect = kernelData + kernelIndex + sectionIndex;␊
191␉␉␉␉␉␊
192␉␉␉␉␉sectionIndex += sizeof(struct section);␊
193␉␉␉␉␉␊
194␉␉␉␉␉␊
195␉␉␉␉␉if(strcmp("__text", sect->sectname) == 0)␊
196␉␉␉␉␉{␊
197␉␉␉␉␉␉// __TEXT,__text found, save the offset and address for when looking for the calls.␊
198␉␉␉␉␉␉textSection = sect->offset;␊
199␉␉␉␉␉␉textAddress = sect->addr;␊
200␉␉␉␉␉␉break;␊
201␉␉␉␉␉}␉␉␉␉␉␊
202␉␉␉␉}␊
203␉␉␉}␊
204␉␉␉␊
205␉␉␉␊
206␉␉␉kernelIndex += cmdSize;␊
207␉␉} else {␊
208␉␉␉kernelIndex += cmdSize;␊
209␉␉}␊
210␉}␊
211␉␊
212␉return KERNEL_32;␊
213}␊
214␊
215␊
216/**␊
217 ** Locate the fisrt instance of _panic inside of _cpuid_set_info, and remove it␊
218 **/␊
219void patch_cpuid_set_info(void* kernelData)␊
220{␊
221␉UInt8* bytes = (UInt8*)kernelData;␊
222␉UInt32 patchLocation = (kernelSymbolAddresses[SYMBOL_CPUID_SET_INFO] - textAddress + textSection);␊
223␉UInt32 panidAddr = kernelSymbolAddresses[SYMBOL_PANIC] - textAddress;␊
224␉if(kernelSymbolAddresses[SYMBOL_CPUID_SET_INFO] == 0)␊
225␉{␊
226␉␉printf("Unable to locate _cpuid_set_info\n");␊
227␉␉return;␊
228␉␉␊
229␉}␊
230␉if(kernelSymbolAddresses[SYMBOL_PANIC] == 0)␊
231␉{␊
232␉␉printf("Unable to locate _panic\n");␊
233␉␉return;␊
234␉}␊
235␉␊
236␉//TODO: don't assume it'll always work (Look for *next* function address in symtab and fail once it's been reached)␊
237␉while( ␊
238␉␉ (bytes[patchLocation -1] != 0xE8) ||␊
239␉␉ ( ( (UInt32)(panidAddr - patchLocation - 4) + textSection ) != (UInt32)((bytes[patchLocation] | ␊
240␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉bytes[patchLocation + 1] << 8 | ␊
241␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉bytes[patchLocation + 2] << 16 |␊
242␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉␉bytes[patchLocation + 3] << 24))) //&&␊
243␉␉ ␊
244␉␉ // (patchLocation < maxLocation)␉// max location is not known... assuming there is a panic call somewhere after cpuid_set_info␊
245␉␉ )␊
246␉{␊
247␉␉//printf("Looking at 0x%X\n", patchLocation);␊
248␉␉patchLocation++;␊
249␉}␊
250␉␊
251␉// repace with nops␊
252␉bytes[patchLocation - 1] = 0x90;␊
253␉bytes[patchLocation ] = 0x90;␊
254␉bytes[patchLocation + 1] = 0x90;␊
255␉bytes[patchLocation + 2] = 0x90;␊
256␉bytes[patchLocation + 3] = 0x90;␊
257}␊
258␊
259␊
260/**␊
261 ** SleepEnabler.kext replacement (for those that need it)␊
262 ** Located the KERN_INVALID_ARGUMENT return and replace it with KERN_SUCCESS␊
263 **/␊
264void patch_pmCPUExitHaltToOff(void* kernelData)␊
265{␊
266␉UInt8* bytes = (UInt8*)kernelData;␊
267␉UInt32 patchLocation = (kernelSymbolAddresses[SYMBOL_PMCPUEXITHALTTOOFF] - textAddress + textSection);␊
268␊
269␉if(kernelSymbolAddresses[SYMBOL_PMCPUEXITHALTTOOFF] == 0)␊
270␉{␊
271␉␉printf("Unable to locate _pmCPUExitHaltToOff\n");␊
272␉␉return;␊
273␉}␊
274␉␊
275␉while(bytes[patchLocation - 1]␉!= 0xB8 ||␊
276␉␉ bytes[patchLocation]␉␉!= 0x04 ||␉// KERN_INVALID_ARGUMENT (0x00000004)␊
277␉␉ bytes[patchLocation + 1]␉!= 0x00 ||␉// KERN_INVALID_ARGUMENT␊
278␉␉ bytes[patchLocation + 2]␉!= 0x00 ||␉// KERN_INVALID_ARGUMENT␊
279␉␉ bytes[patchLocation + 3]␉!= 0x00)␉// KERN_INVALID_ARGUMENT␊
280␊
281␉{␊
282␉␉patchLocation++;␊
283␉}␊
284␉bytes[patchLocation] = 0x00;␉// KERN_SUCCESS;␊
285}␊
286

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