| /* |
| * Copyright (C) 2009 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include <errno.h> |
| #include <sys/stat.h> |
| #include <fcntl.h> |
| #include <stdio.h> |
| #include <unistd.h> |
| #include <string.h> |
| #include <strings.h> |
| #include "Retouch.h" |
| #include "applypatch/applypatch.h" |
| |
| typedef struct { |
| int32_t mmap_addr; |
| char tag[4]; /* 'P', 'R', 'E', ' ' */ |
| } prelink_info_t __attribute__((packed)); |
| |
| #define false 0 |
| #define true 1 |
| |
| static int32_t offs_prev; |
| static uint32_t cont_prev; |
| |
| static void init_compression_state(void) { |
| offs_prev = 0; |
| cont_prev = 0; |
| } |
| |
| // For details on the encoding used for relocation lists, please |
| // refer to build/tools/retouch/retouch-prepare.c. The intent is to |
| // save space by removing most of the inherent redundancy. |
| |
| static void decode_bytes(uint8_t *encoded_bytes, int encoded_size, |
| int32_t *dst_offset, uint32_t *dst_contents) { |
| if (encoded_size == 2) { |
| *dst_offset = offs_prev + (((encoded_bytes[0]&0x60)>>5)+1)*4; |
| |
| // if the original was negative, we need to 1-pad before applying delta |
| int32_t tmp = (((encoded_bytes[0] & 0x0000001f) << 8) | |
| encoded_bytes[1]); |
| if (tmp & 0x1000) tmp = 0xffffe000 | tmp; |
| *dst_contents = cont_prev + tmp; |
| } else if (encoded_size == 3) { |
| *dst_offset = offs_prev + (((encoded_bytes[0]&0x30)>>4)+1)*4; |
| |
| // if the original was negative, we need to 1-pad before applying delta |
| int32_t tmp = (((encoded_bytes[0] & 0x0000000f) << 16) | |
| (encoded_bytes[1] << 8) | |
| encoded_bytes[2]); |
| if (tmp & 0x80000) tmp = 0xfff00000 | tmp; |
| *dst_contents = cont_prev + tmp; |
| } else { |
| *dst_offset = |
| (encoded_bytes[0]<<24) | |
| (encoded_bytes[1]<<16) | |
| (encoded_bytes[2]<<8) | |
| encoded_bytes[3]; |
| if (*dst_offset == 0x3fffffff) *dst_offset = -1; |
| *dst_contents = |
| (encoded_bytes[4]<<24) | |
| (encoded_bytes[5]<<16) | |
| (encoded_bytes[6]<<8) | |
| encoded_bytes[7]; |
| } |
| } |
| |
| static uint8_t *decode_in_memory(uint8_t *encoded_bytes, |
| int32_t *offset, uint32_t *contents) { |
| int input_size, charIx; |
| uint8_t input[8]; |
| |
| input[0] = *(encoded_bytes++); |
| if (input[0] & 0x80) |
| input_size = 2; |
| else if (input[0] & 0x40) |
| input_size = 3; |
| else |
| input_size = 8; |
| |
| // we already read one byte.. |
| charIx = 1; |
| while (charIx < input_size) { |
| input[charIx++] = *(encoded_bytes++); |
| } |
| |
| // depends on the decoder state! |
| decode_bytes(input, input_size, offset, contents); |
| |
| offs_prev = *offset; |
| cont_prev = *contents; |
| |
| return encoded_bytes; |
| } |
| |
| int retouch_mask_data(uint8_t *binary_object, |
| int32_t binary_size, |
| int32_t *desired_offset, |
| int32_t *retouch_offset) { |
| retouch_info_t *r_info; |
| prelink_info_t *p_info; |
| |
| int32_t target_offset = 0; |
| if (desired_offset) target_offset = *desired_offset; |
| |
| int32_t p_offs = binary_size-sizeof(prelink_info_t); // prelink_info_t |
| int32_t r_offs = p_offs-sizeof(retouch_info_t); // retouch_info_t |
| int32_t b_offs; // retouch data blob |
| |
| // If not retouched, we say it was a match. This might get invoked on |
| // non-retouched binaries, so that's why we need to do this. |
| if (retouch_offset != NULL) *retouch_offset = target_offset; |
| if (r_offs < 0) return (desired_offset == NULL) ? |
| RETOUCH_DATA_NOTAPPLICABLE : RETOUCH_DATA_MATCHED; |
| p_info = (prelink_info_t *)(binary_object+p_offs); |
| r_info = (retouch_info_t *)(binary_object+r_offs); |
| if (strncmp(p_info->tag, "PRE ", 4) || |
| strncmp(r_info->tag, "RETOUCH ", 8)) |
| return (desired_offset == NULL) ? |
| RETOUCH_DATA_NOTAPPLICABLE : RETOUCH_DATA_MATCHED; |
| |
| b_offs = r_offs-r_info->blob_size; |
| if (b_offs < 0) { |
| printf("negative binary offset: %d = %d - %d\n", |
| b_offs, r_offs, r_info->blob_size); |
| return RETOUCH_DATA_ERROR; |
| } |
| uint8_t *b_ptr = binary_object+b_offs; |
| |
| // Retouched: let's go through the work then. |
| int32_t offset_candidate = target_offset; |
| bool offset_set = false, offset_mismatch = false; |
| init_compression_state(); |
| while (b_ptr < (uint8_t *)r_info) { |
| int32_t retouch_entry_offset; |
| uint32_t *retouch_entry; |
| uint32_t retouch_original_value; |
| |
| b_ptr = decode_in_memory(b_ptr, |
| &retouch_entry_offset, |
| &retouch_original_value); |
| if (retouch_entry_offset < (-1) || |
| retouch_entry_offset >= b_offs) { |
| printf("bad retouch_entry_offset: %d", retouch_entry_offset); |
| return RETOUCH_DATA_ERROR; |
| } |
| |
| // "-1" means this is the value in prelink_info_t, which also gets |
| // randomized. |
| if (retouch_entry_offset == -1) |
| retouch_entry = (uint32_t *)&(p_info->mmap_addr); |
| else |
| retouch_entry = (uint32_t *)(binary_object+retouch_entry_offset); |
| |
| if (desired_offset) |
| *retouch_entry = retouch_original_value + target_offset; |
| |
| // Infer the randomization shift, compare to previously inferred. |
| int32_t offset_of_this_entry = (int32_t)(*retouch_entry- |
| retouch_original_value); |
| if (!offset_set) { |
| offset_candidate = offset_of_this_entry; |
| offset_set = true; |
| } else { |
| if (offset_candidate != offset_of_this_entry) { |
| offset_mismatch = true; |
| printf("offset is mismatched: %d, this entry is %d," |
| " original 0x%x @ 0x%x", |
| offset_candidate, offset_of_this_entry, |
| retouch_original_value, retouch_entry_offset); |
| } |
| } |
| } |
| if (b_ptr > (uint8_t *)r_info) { |
| printf("b_ptr went too far: %p, while r_info is %p", |
| b_ptr, r_info); |
| return RETOUCH_DATA_ERROR; |
| } |
| |
| if (offset_mismatch) return RETOUCH_DATA_MISMATCHED; |
| if (retouch_offset != NULL) *retouch_offset = offset_candidate; |
| return RETOUCH_DATA_MATCHED; |
| } |
