build/unix/elfhack/inject.c@ac0c01689b40 (annotated)
build/unix/elfhack/inject.c
Thu, 15 Jan 2015 15:59:08 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 15 Jan 2015 15:59:08 +0100
- branch
- TOR_BUG_9701
- changeset 10
- ac0c01689b40
- permissions
- -rw-r--r--
Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
| michael@0 | 1 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 2 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 3 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 4 | |
| michael@0 | 5 | #include <stdint.h> |
| michael@0 | 6 | #include <elf.h> |
| michael@0 | 7 | |
| michael@0 | 8 | /* The Android NDK headers define those */ |
| michael@0 | 9 | #undef Elf_Ehdr |
| michael@0 | 10 | #undef Elf_Addr |
| michael@0 | 11 | |
| michael@0 | 12 | #if defined(__LP64__) |
| michael@0 | 13 | #define Elf_Ehdr Elf64_Ehdr |
| michael@0 | 14 | #define Elf_Addr Elf64_Addr |
| michael@0 | 15 | #else |
| michael@0 | 16 | #define Elf_Ehdr Elf32_Ehdr |
| michael@0 | 17 | #define Elf_Addr Elf32_Addr |
| michael@0 | 18 | #endif |
| michael@0 | 19 | |
| michael@0 | 20 | extern __attribute__((visibility("hidden"))) void original_init(int argc, char **argv, char **env); |
| michael@0 | 21 | |
| michael@0 | 22 | extern __attribute__((visibility("hidden"))) Elf32_Rel relhack[]; |
| michael@0 | 23 | extern __attribute__((visibility("hidden"))) Elf_Ehdr elf_header; |
| michael@0 | 24 | |
| michael@0 | 25 | static inline __attribute__((always_inline)) |
| michael@0 | 26 | void do_relocations(void) |
| michael@0 | 27 | { |
| michael@0 | 28 | Elf32_Rel *rel; |
| michael@0 | 29 | Elf_Addr *ptr, *start; |
| michael@0 | 30 | for (rel = relhack; rel->r_offset; rel++) { |
| michael@0 | 31 | start = (Elf_Addr *)((intptr_t)&elf_header + rel->r_offset); |
| michael@0 | 32 | for (ptr = start; ptr < &start[rel->r_info]; ptr++) |
| michael@0 | 33 | *ptr += (intptr_t)&elf_header; |
| michael@0 | 34 | } |
| michael@0 | 35 | } |
| michael@0 | 36 | |
| michael@0 | 37 | __attribute__((section(".text._init_noinit"))) |
| michael@0 | 38 | int init_noinit(int argc, char **argv, char **env) |
| michael@0 | 39 | { |
| michael@0 | 40 | do_relocations(); |
| michael@0 | 41 | return 0; |
| michael@0 | 42 | } |
| michael@0 | 43 | |
| michael@0 | 44 | __attribute__((section(".text._init"))) |
| michael@0 | 45 | int init(int argc, char **argv, char **env) |
| michael@0 | 46 | { |
| michael@0 | 47 | do_relocations(); |
| michael@0 | 48 | original_init(argc, argv, env); |
| michael@0 | 49 | // Ensure there is no tail-call optimization, avoiding the use of the |
| michael@0 | 50 | // B.W instruction in Thumb for the call above. |
| michael@0 | 51 | return 0; |
| michael@0 | 52 | } |
