hook 拦截 socket数据

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