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      1 #include <openssl/bn.h>
      2 #include <openssl/evp.h>
      3 #include <sparse/sparse.h>
      4 
      5 #undef NDEBUG
      6 
      7 #include <assert.h>
      8 #include <errno.h>
      9 #include <getopt.h>
     10 #include <fcntl.h>
     11 #include <inttypes.h>
     12 #include <limits.h>
     13 #include <stdio.h>
     14 #include <stdlib.h>
     15 #include <string.h>
     16 #include <unistd.h>
     17 #include <vector>
     18 
     19 #include <android-base/file.h>
     20 
     21 struct sparse_hash_ctx {
     22     unsigned char *hashes;
     23     const unsigned char *salt;
     24     uint64_t salt_size;
     25     uint64_t hash_size;
     26     uint64_t block_size;
     27     const unsigned char *zero_block_hash;
     28     const EVP_MD *md;
     29 };
     30 
     31 #define div_round_up(x,y) (((x) + (y) - 1)/(y))
     32 
     33 #define round_up(x,y) (div_round_up(x,y)*(y))
     34 
     35 #define FATAL(x...) { \
     36     fprintf(stderr, x); \
     37     exit(1); \
     38 }
     39 
     40 size_t verity_tree_blocks(uint64_t data_size, size_t block_size, size_t hash_size,
     41                           int level)
     42 {
     43     size_t level_blocks = div_round_up(data_size, block_size);
     44     int hashes_per_block = div_round_up(block_size, hash_size);
     45 
     46     do {
     47         level_blocks = div_round_up(level_blocks, hashes_per_block);
     48     } while (level--);
     49 
     50     return level_blocks;
     51 }
     52 
     53 int hash_block(const EVP_MD *md,
     54                const unsigned char *block, size_t len,
     55                const unsigned char *salt, size_t salt_len,
     56                unsigned char *out, size_t *out_size)
     57 {
     58     EVP_MD_CTX *mdctx;
     59     unsigned int s;
     60     int ret = 1;
     61 
     62     mdctx = EVP_MD_CTX_create();
     63     assert(mdctx);
     64     ret &= EVP_DigestInit_ex(mdctx, md, NULL);
     65     ret &= EVP_DigestUpdate(mdctx, salt, salt_len);
     66     ret &= EVP_DigestUpdate(mdctx, block, len);
     67     ret &= EVP_DigestFinal_ex(mdctx, out, &s);
     68     EVP_MD_CTX_destroy(mdctx);
     69     assert(ret == 1);
     70     if (out_size) {
     71         *out_size = s;
     72     }
     73     return 0;
     74 }
     75 
     76 int hash_blocks(const EVP_MD *md,
     77                 const unsigned char *in, size_t in_size,
     78                 unsigned char *out, size_t *out_size,
     79                 const unsigned char *salt, size_t salt_size,
     80                 size_t block_size)
     81 {
     82     size_t s;
     83     *out_size = 0;
     84     for (size_t i = 0; i < in_size; i += block_size) {
     85         hash_block(md, in + i, block_size, salt, salt_size, out, &s);
     86         out += s;
     87         *out_size += s;
     88     }
     89 
     90     return 0;
     91 }
     92 
     93 int hash_chunk(void *priv, const void *data, int len)
     94 {
     95     struct sparse_hash_ctx *ctx = (struct sparse_hash_ctx *)priv;
     96     assert(len % ctx->block_size == 0);
     97     if (data) {
     98         size_t s;
     99         hash_blocks(ctx->md, (const unsigned char *)data, len,
    100                     ctx->hashes, &s,
    101                     ctx->salt, ctx->salt_size, ctx->block_size);
    102         ctx->hashes += s;
    103     } else {
    104         for (size_t i = 0; i < (size_t)len; i += ctx->block_size) {
    105             memcpy(ctx->hashes, ctx->zero_block_hash, ctx->hash_size);
    106             ctx->hashes += ctx->hash_size;
    107         }
    108     }
    109     return 0;
    110 }
    111 
    112 void usage(void)
    113 {
    114     printf("usage: build_verity_tree [ <options> ] -s <size> | <data> <verity>\n"
    115            "options:\n"
    116            "  -a,--salt-str=<string>       set salt to <string>\n"
    117            "  -A,--salt-hex=<hex digits>   set salt to <hex digits>\n"
    118            "  -h                           show this help\n"
    119            "  -s,--verity-size=<data size> print the size of the verity tree\n"
    120            "  -v,                          enable verbose logging\n"
    121            "  -S                           treat <data image> as a sparse file\n"
    122         );
    123 }
    124 
    125 int main(int argc, char **argv)
    126 {
    127     char *data_filename;
    128     char *verity_filename;
    129     std::vector<unsigned char> salt;
    130     bool sparse = false;
    131     size_t block_size = 4096;
    132     uint64_t calculate_size = 0;
    133     bool verbose = false;
    134 
    135     while (1) {
    136         const static struct option long_options[] = {
    137             {"salt-str", required_argument, 0, 'a'},
    138             {"salt-hex", required_argument, 0, 'A'},
    139             {"help", no_argument, 0, 'h'},
    140             {"sparse", no_argument, 0, 'S'},
    141             {"verity-size", required_argument, 0, 's'},
    142             {"verbose", no_argument, 0, 'v'},
    143             {NULL, 0, 0, 0}
    144         };
    145         int c = getopt_long(argc, argv, "a:A:hSs:v", long_options, NULL);
    146         if (c < 0) {
    147             break;
    148         }
    149 
    150         switch (c) {
    151         case 'a':
    152             salt.clear();
    153             salt.insert(salt.end(), optarg, &optarg[strlen(optarg)]);
    154             break;
    155         case 'A': {
    156                 BIGNUM *bn = NULL;
    157                 if(!BN_hex2bn(&bn, optarg)) {
    158                     FATAL("failed to convert salt from hex\n");
    159                 }
    160                 size_t salt_size = BN_num_bytes(bn);
    161                 salt.resize(salt_size);
    162                 if (BN_bn2bin(bn, salt.data()) != salt_size) {
    163                     FATAL("failed to convert salt to bytes\n");
    164                 }
    165             }
    166             break;
    167         case 'h':
    168             usage();
    169             return 1;
    170         case 'S':
    171             sparse = true;
    172             break;
    173         case 's': {
    174                 char* endptr;
    175                 errno = 0;
    176                 unsigned long long int inSize = strtoull(optarg, &endptr, 0);
    177                 if (optarg[0] == '\0' || *endptr != '\0' ||
    178                         (errno == ERANGE && inSize == ULLONG_MAX)) {
    179                     FATAL("invalid value of verity-size\n");
    180                 }
    181                 if (inSize > UINT64_MAX) {
    182                     FATAL("invalid value of verity-size\n");
    183                 }
    184                 calculate_size = (uint64_t)inSize;
    185             }
    186             break;
    187         case 'v':
    188             verbose = true;
    189             break;
    190         case '?':
    191             usage();
    192             return 1;
    193         default:
    194             abort();
    195         }
    196     }
    197 
    198     argc -= optind;
    199     argv += optind;
    200 
    201     const EVP_MD *md = EVP_sha256();
    202     if (!md) {
    203         FATAL("failed to get digest\n");
    204     }
    205 
    206     size_t hash_size = EVP_MD_size(md);
    207     assert(hash_size * 2 < block_size);
    208 
    209     if (salt.empty()) {
    210         salt.resize(hash_size);
    211 
    212         int random_fd = open("/dev/urandom", O_RDONLY);
    213         if (random_fd < 0) {
    214             FATAL("failed to open /dev/urandom\n");
    215         }
    216 
    217         ssize_t ret = read(random_fd, salt.data(), salt.size());
    218         if (ret != static_cast<ssize_t>(salt.size())) {
    219             FATAL("failed to read %zu bytes from /dev/urandom: %zd %d\n", salt.size(), ret, errno);
    220         }
    221         close(random_fd);
    222     }
    223 
    224     if (calculate_size) {
    225         if (argc != 0) {
    226             usage();
    227             return 1;
    228         }
    229         size_t verity_blocks = 0;
    230         size_t level_blocks;
    231         int levels = 0;
    232         do {
    233             level_blocks = verity_tree_blocks(calculate_size, block_size, hash_size, levels);
    234             levels++;
    235             verity_blocks += level_blocks;
    236         } while (level_blocks > 1);
    237 
    238         printf("%" PRIu64 "\n", (uint64_t)verity_blocks * block_size);
    239         return 0;
    240     }
    241 
    242     if (argc != 2) {
    243         usage();
    244         return 1;
    245     }
    246 
    247     data_filename = argv[0];
    248     verity_filename = argv[1];
    249 
    250     int fd = open(data_filename, O_RDONLY);
    251     if (fd < 0) {
    252         FATAL("failed to open %s\n", data_filename);
    253     }
    254 
    255     struct sparse_file *file;
    256     if (sparse) {
    257         file = sparse_file_import(fd, false, false);
    258     } else {
    259         file = sparse_file_import_auto(fd, false, verbose);
    260     }
    261 
    262     if (!file) {
    263         FATAL("failed to read file %s\n", data_filename);
    264     }
    265 
    266     int64_t len = sparse_file_len(file, false, false);
    267     if (len % block_size != 0) {
    268         FATAL("file size %" PRIu64 " is not a multiple of %zu bytes\n",
    269                 len, block_size);
    270     }
    271 
    272     int levels = 0;
    273     size_t verity_blocks = 0;
    274     size_t level_blocks;
    275 
    276     do {
    277         level_blocks = verity_tree_blocks(len, block_size, hash_size, levels);
    278         levels++;
    279         verity_blocks += level_blocks;
    280     } while (level_blocks > 1);
    281 
    282     unsigned char *verity_tree = new unsigned char[verity_blocks * block_size]();
    283     unsigned char **verity_tree_levels = new unsigned char *[levels + 1]();
    284     size_t *verity_tree_level_blocks = new size_t[levels]();
    285     if (verity_tree == NULL || verity_tree_levels == NULL || verity_tree_level_blocks == NULL) {
    286         FATAL("failed to allocate memory for verity tree\n");
    287     }
    288 
    289     unsigned char *ptr = verity_tree;
    290     for (int i = levels - 1; i >= 0; i--) {
    291         verity_tree_levels[i] = ptr;
    292         verity_tree_level_blocks[i] = verity_tree_blocks(len, block_size, hash_size, i);
    293         ptr += verity_tree_level_blocks[i] * block_size;
    294     }
    295     assert(ptr == verity_tree + verity_blocks * block_size);
    296     assert(verity_tree_level_blocks[levels - 1] == 1);
    297 
    298     unsigned char zero_block_hash[hash_size];
    299     unsigned char zero_block[block_size];
    300     memset(zero_block, 0, block_size);
    301     hash_block(md, zero_block, block_size, salt.data(), salt.size(), zero_block_hash, NULL);
    302 
    303     unsigned char root_hash[hash_size];
    304     verity_tree_levels[levels] = root_hash;
    305 
    306     struct sparse_hash_ctx ctx;
    307     ctx.hashes = verity_tree_levels[0];
    308     ctx.salt = salt.data();
    309     ctx.salt_size = salt.size();
    310     ctx.hash_size = hash_size;
    311     ctx.block_size = block_size;
    312     ctx.zero_block_hash = zero_block_hash;
    313     ctx.md = md;
    314 
    315     sparse_file_callback(file, false, false, hash_chunk, &ctx);
    316 
    317     sparse_file_destroy(file);
    318     close(fd);
    319 
    320     for (int i = 0; i < levels; i++) {
    321         size_t out_size;
    322         hash_blocks(md,
    323                 verity_tree_levels[i], verity_tree_level_blocks[i] * block_size,
    324                 verity_tree_levels[i + 1], &out_size,
    325                 salt.data(), salt.size(), block_size);
    326           if (i < levels - 1) {
    327               assert(div_round_up(out_size, block_size) == verity_tree_level_blocks[i + 1]);
    328           } else {
    329               assert(out_size == hash_size);
    330           }
    331     }
    332 
    333     for (size_t i = 0; i < hash_size; i++) {
    334         printf("%02x", root_hash[i]);
    335     }
    336     printf(" ");
    337     for (size_t i = 0; i < salt.size(); i++) {
    338         printf("%02x", salt[i]);
    339     }
    340     printf("\n");
    341 
    342     fd = open(verity_filename, O_WRONLY|O_CREAT, 0666);
    343     if (fd < 0) {
    344         FATAL("failed to open output file '%s'\n", verity_filename);
    345     }
    346     if (!android::base::WriteFully(fd, verity_tree, verity_blocks * block_size)) {
    347         FATAL("failed to write '%s'\n", verity_filename);
    348     }
    349     close(fd);
    350 
    351     delete[] verity_tree_levels;
    352     delete[] verity_tree_level_blocks;
    353     delete[] verity_tree;
    354 }
    355