211 lines
8.3 KiB
C
Executable File
211 lines
8.3 KiB
C
Executable File
// Copyright (c) 2013, Facebook, Inc.
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// All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name Facebook nor the names of its contributors may be used to
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// endorse or promote products derived from this software without specific
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// prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#import "fishhook.h"
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#import <dlfcn.h>
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#import <stdlib.h>
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#import <string.h>
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#import <sys/types.h>
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#import <mach-o/dyld.h>
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#import <mach-o/loader.h>
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#import <mach-o/nlist.h>
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#ifdef __LP64__
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typedef struct mach_header_64 mach_header_t;
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typedef struct segment_command_64 segment_command_t;
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typedef struct section_64 section_t;
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typedef struct nlist_64 nlist_t;
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#define LC_SEGMENT_ARCH_DEPENDENT LC_SEGMENT_64
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#else
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typedef struct mach_header mach_header_t;
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typedef struct segment_command segment_command_t;
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typedef struct section section_t;
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typedef struct nlist nlist_t;
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#define LC_SEGMENT_ARCH_DEPENDENT LC_SEGMENT
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#endif
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#ifndef SEG_DATA_CONST
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#define SEG_DATA_CONST "__DATA_CONST"
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#endif
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struct rebindings_entry {
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struct rebinding *rebindings;
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size_t rebindings_nel;
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struct rebindings_entry *next;
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};
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static struct rebindings_entry *_rebindings_head;
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static int prepend_rebindings(struct rebindings_entry **rebindings_head,
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struct rebinding rebindings[],
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size_t nel) {
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struct rebindings_entry *new_entry = (struct rebindings_entry *) malloc(sizeof(struct rebindings_entry));
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if (!new_entry) {
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return -1;
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}
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new_entry->rebindings = (struct rebinding *) malloc(sizeof(struct rebinding) * nel);
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if (!new_entry->rebindings) {
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free(new_entry);
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return -1;
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}
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memcpy(new_entry->rebindings, rebindings, sizeof(struct rebinding) * nel);
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new_entry->rebindings_nel = nel;
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new_entry->next = *rebindings_head;
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*rebindings_head = new_entry;
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return 0;
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}
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static void perform_rebinding_with_section(struct rebindings_entry *rebindings,
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section_t *section,
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intptr_t slide,
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nlist_t *symtab,
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char *strtab,
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uint32_t *indirect_symtab) {
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uint32_t *indirect_symbol_indices = indirect_symtab + section->reserved1;
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void **indirect_symbol_bindings = (void **)((uintptr_t)slide + section->addr);
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for (uint i = 0; i < section->size / sizeof(void *); i++) {
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uint32_t symtab_index = indirect_symbol_indices[i];
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if (symtab_index == INDIRECT_SYMBOL_ABS || symtab_index == INDIRECT_SYMBOL_LOCAL ||
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symtab_index == (INDIRECT_SYMBOL_LOCAL | INDIRECT_SYMBOL_ABS)) {
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continue;
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}
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uint32_t strtab_offset = symtab[symtab_index].n_un.n_strx;
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char *symbol_name = strtab + strtab_offset;
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if (strnlen(symbol_name, 2) < 2) {
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continue;
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}
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struct rebindings_entry *cur = rebindings;
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while (cur) {
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for (uint j = 0; j < cur->rebindings_nel; j++) {
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if (strcmp(&symbol_name[1], cur->rebindings[j].name) == 0) {
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if (cur->rebindings[j].replaced != NULL &&
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indirect_symbol_bindings[i] != cur->rebindings[j].replacement) {
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*(cur->rebindings[j].replaced) = indirect_symbol_bindings[i];
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}
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indirect_symbol_bindings[i] = cur->rebindings[j].replacement;
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goto symbol_loop;
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}
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}
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cur = cur->next;
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}
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symbol_loop:;
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}
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}
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static void rebind_symbols_for_image(struct rebindings_entry *rebindings,
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const struct mach_header *header,
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intptr_t slide) {
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Dl_info info;
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if (dladdr(header, &info) == 0) {
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return;
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}
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segment_command_t *cur_seg_cmd;
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segment_command_t *linkedit_segment = NULL;
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struct symtab_command* symtab_cmd = NULL;
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struct dysymtab_command* dysymtab_cmd = NULL;
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uintptr_t cur = (uintptr_t)header + sizeof(mach_header_t);
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for (uint i = 0; i < header->ncmds; i++, cur += cur_seg_cmd->cmdsize) {
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cur_seg_cmd = (segment_command_t *)cur;
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if (cur_seg_cmd->cmd == LC_SEGMENT_ARCH_DEPENDENT) {
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if (strcmp(cur_seg_cmd->segname, SEG_LINKEDIT) == 0) {
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linkedit_segment = cur_seg_cmd;
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}
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} else if (cur_seg_cmd->cmd == LC_SYMTAB) {
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symtab_cmd = (struct symtab_command*)cur_seg_cmd;
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} else if (cur_seg_cmd->cmd == LC_DYSYMTAB) {
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dysymtab_cmd = (struct dysymtab_command*)cur_seg_cmd;
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}
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}
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if (!symtab_cmd || !dysymtab_cmd || !linkedit_segment ||
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!dysymtab_cmd->nindirectsyms) {
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return;
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}
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// Find base symbol/string table addresses
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uintptr_t linkedit_base = (uintptr_t)slide + linkedit_segment->vmaddr - linkedit_segment->fileoff;
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nlist_t *symtab = (nlist_t *)(linkedit_base + symtab_cmd->symoff);
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char *strtab = (char *)(linkedit_base + symtab_cmd->stroff);
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// Get indirect symbol table (array of uint32_t indices into symbol table)
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uint32_t *indirect_symtab = (uint32_t *)(linkedit_base + dysymtab_cmd->indirectsymoff);
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cur = (uintptr_t)header + sizeof(mach_header_t);
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for (uint i = 0; i < header->ncmds; i++, cur += cur_seg_cmd->cmdsize) {
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cur_seg_cmd = (segment_command_t *)cur;
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if (cur_seg_cmd->cmd == LC_SEGMENT_ARCH_DEPENDENT) {
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if (strcmp(cur_seg_cmd->segname, SEG_DATA) != 0 &&
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strcmp(cur_seg_cmd->segname, SEG_DATA_CONST) != 0) {
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continue;
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}
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for (uint j = 0; j < cur_seg_cmd->nsects; j++) {
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section_t *sect =
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(section_t *)(cur + sizeof(segment_command_t)) + j;
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if ((sect->flags & SECTION_TYPE) == S_LAZY_SYMBOL_POINTERS) {
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perform_rebinding_with_section(rebindings, sect, slide, symtab, strtab, indirect_symtab);
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}
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if ((sect->flags & SECTION_TYPE) == S_NON_LAZY_SYMBOL_POINTERS) {
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perform_rebinding_with_section(rebindings, sect, slide, symtab, strtab, indirect_symtab);
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}
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}
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}
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}
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}
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static void _rebind_symbols_for_image(const struct mach_header *header,
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intptr_t slide) {
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rebind_symbols_for_image(_rebindings_head, header, slide);
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}
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int rebind_symbols_image(void *header,
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intptr_t slide,
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struct rebinding rebindings[],
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size_t rebindings_nel) {
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struct rebindings_entry *rebindings_head = NULL;
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int retval = prepend_rebindings(&rebindings_head, rebindings, rebindings_nel);
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rebind_symbols_for_image(rebindings_head, (const struct mach_header *) header, slide);
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free(rebindings_head);
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return retval;
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}
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int rebind_symbols(struct rebinding rebindings[], size_t rebindings_nel) {
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int retval = prepend_rebindings(&_rebindings_head, rebindings, rebindings_nel);
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if (retval < 0) {
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return retval;
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}
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// If this was the first call, register callback for image additions (which is also invoked for
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// existing images, otherwise, just run on existing images
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if (!_rebindings_head->next) {
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_dyld_register_func_for_add_image(_rebind_symbols_for_image);
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} else {
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uint32_t c = _dyld_image_count();
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for (uint32_t i = 0; i < c; i++) {
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_rebind_symbols_for_image(_dyld_get_image_header(i), _dyld_get_image_vmaddr_slide(i));
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}
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}
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return retval;
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}
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