1 /* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <errno.h> 18 #include <sys/stat.h> 19 #include <fcntl.h> 20 #include <stdio.h> 21 #include <unistd.h> 22 #include <string.h> 23 #include <strings.h> 24 #include "Retouch.h" 25 #include "applypatch/applypatch.h" 26 27 typedef struct { 28 int32_t mmap_addr; 29 char tag[4]; /* 'P', 'R', 'E', ' ' */ 30 } prelink_info_t __attribute__((packed)); 31 32 #define false 0 33 #define true 1 34 35 static int32_t offs_prev; 36 static uint32_t cont_prev; 37 38 static void init_compression_state(void) { 39 offs_prev = 0; 40 cont_prev = 0; 41 } 42 43 // For details on the encoding used for relocation lists, please 44 // refer to build/tools/retouch/retouch-prepare.c. The intent is to 45 // save space by removing most of the inherent redundancy. 46 47 static void decode_bytes(uint8_t *encoded_bytes, int encoded_size, 48 int32_t *dst_offset, uint32_t *dst_contents) { 49 if (encoded_size == 2) { 50 *dst_offset = offs_prev + (((encoded_bytes[0]&0x60)>>5)+1)*4; 51 52 // if the original was negative, we need to 1-pad before applying delta 53 int32_t tmp = (((encoded_bytes[0] & 0x0000001f) << 8) | 54 encoded_bytes[1]); 55 if (tmp & 0x1000) tmp = 0xffffe000 | tmp; 56 *dst_contents = cont_prev + tmp; 57 } else if (encoded_size == 3) { 58 *dst_offset = offs_prev + (((encoded_bytes[0]&0x30)>>4)+1)*4; 59 60 // if the original was negative, we need to 1-pad before applying delta 61 int32_t tmp = (((encoded_bytes[0] & 0x0000000f) << 16) | 62 (encoded_bytes[1] << 8) | 63 encoded_bytes[2]); 64 if (tmp & 0x80000) tmp = 0xfff00000 | tmp; 65 *dst_contents = cont_prev + tmp; 66 } else { 67 *dst_offset = 68 (encoded_bytes[0]<<24) | 69 (encoded_bytes[1]<<16) | 70 (encoded_bytes[2]<<8) | 71 encoded_bytes[3]; 72 if (*dst_offset == 0x3fffffff) *dst_offset = -1; 73 *dst_contents = 74 (encoded_bytes[4]<<24) | 75 (encoded_bytes[5]<<16) | 76 (encoded_bytes[6]<<8) | 77 encoded_bytes[7]; 78 } 79 } 80 81 static uint8_t *decode_in_memory(uint8_t *encoded_bytes, 82 int32_t *offset, uint32_t *contents) { 83 int input_size, charIx; 84 uint8_t input[8]; 85 86 input[0] = *(encoded_bytes++); 87 if (input[0] & 0x80) 88 input_size = 2; 89 else if (input[0] & 0x40) 90 input_size = 3; 91 else 92 input_size = 8; 93 94 // we already read one byte.. 95 charIx = 1; 96 while (charIx < input_size) { 97 input[charIx++] = *(encoded_bytes++); 98 } 99 100 // depends on the decoder state! 101 decode_bytes(input, input_size, offset, contents); 102 103 offs_prev = *offset; 104 cont_prev = *contents; 105 106 return encoded_bytes; 107 } 108 109 int retouch_mask_data(uint8_t *binary_object, 110 int32_t binary_size, 111 int32_t *desired_offset, 112 int32_t *retouch_offset) { 113 retouch_info_t *r_info; 114 prelink_info_t *p_info; 115 116 int32_t target_offset = 0; 117 if (desired_offset) target_offset = *desired_offset; 118 119 int32_t p_offs = binary_size-sizeof(prelink_info_t); // prelink_info_t 120 int32_t r_offs = p_offs-sizeof(retouch_info_t); // retouch_info_t 121 int32_t b_offs; // retouch data blob 122 123 // If not retouched, we say it was a match. This might get invoked on 124 // non-retouched binaries, so that's why we need to do this. 125 if (retouch_offset != NULL) *retouch_offset = target_offset; 126 if (r_offs < 0) return (desired_offset == NULL) ? 127 RETOUCH_DATA_NOTAPPLICABLE : RETOUCH_DATA_MATCHED; 128 p_info = (prelink_info_t *)(binary_object+p_offs); 129 r_info = (retouch_info_t *)(binary_object+r_offs); 130 if (strncmp(p_info->tag, "PRE ", 4) || 131 strncmp(r_info->tag, "RETOUCH ", 8)) 132 return (desired_offset == NULL) ? 133 RETOUCH_DATA_NOTAPPLICABLE : RETOUCH_DATA_MATCHED; 134 135 b_offs = r_offs-r_info->blob_size; 136 if (b_offs < 0) { 137 printf("negative binary offset: %d = %d - %d\n", 138 b_offs, r_offs, r_info->blob_size); 139 return RETOUCH_DATA_ERROR; 140 } 141 uint8_t *b_ptr = binary_object+b_offs; 142 143 // Retouched: let's go through the work then. 144 int32_t offset_candidate = target_offset; 145 bool offset_set = false, offset_mismatch = false; 146 init_compression_state(); 147 while (b_ptr < (uint8_t *)r_info) { 148 int32_t retouch_entry_offset; 149 uint32_t *retouch_entry; 150 uint32_t retouch_original_value; 151 152 b_ptr = decode_in_memory(b_ptr, 153 &retouch_entry_offset, 154 &retouch_original_value); 155 if (retouch_entry_offset < (-1) || 156 retouch_entry_offset >= b_offs) { 157 printf("bad retouch_entry_offset: %d", retouch_entry_offset); 158 return RETOUCH_DATA_ERROR; 159 } 160 161 // "-1" means this is the value in prelink_info_t, which also gets 162 // randomized. 163 if (retouch_entry_offset == -1) 164 retouch_entry = (uint32_t *)&(p_info->mmap_addr); 165 else 166 retouch_entry = (uint32_t *)(binary_object+retouch_entry_offset); 167 168 if (desired_offset) 169 *retouch_entry = retouch_original_value + target_offset; 170 171 // Infer the randomization shift, compare to previously inferred. 172 int32_t offset_of_this_entry = (int32_t)(*retouch_entry- 173 retouch_original_value); 174 if (!offset_set) { 175 offset_candidate = offset_of_this_entry; 176 offset_set = true; 177 } else { 178 if (offset_candidate != offset_of_this_entry) { 179 offset_mismatch = true; 180 printf("offset is mismatched: %d, this entry is %d," 181 " original 0x%x @ 0x%x", 182 offset_candidate, offset_of_this_entry, 183 retouch_original_value, retouch_entry_offset); 184 } 185 } 186 } 187 if (b_ptr > (uint8_t *)r_info) { 188 printf("b_ptr went too far: %p, while r_info is %p", 189 b_ptr, r_info); 190 return RETOUCH_DATA_ERROR; 191 } 192 193 if (offset_mismatch) return RETOUCH_DATA_MISMATCHED; 194 if (retouch_offset != NULL) *retouch_offset = offset_candidate; 195 return RETOUCH_DATA_MATCHED; 196 } 197
