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      1 //
      2 // Copyright (C) 2015 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 "update_engine/payload_generator/ext2_filesystem.h"
     18 
     19 #include <et/com_err.h>
     20 // TODO: Remove these pragmas when b/35721782 is fixed.
     21 #pragma clang diagnostic push
     22 #pragma clang diagnostic ignored "-Wmacro-redefined"
     23 #include <ext2fs/ext2_io.h>
     24 #include <ext2fs/ext2fs.h>
     25 #pragma clang diagnostic pop
     26 
     27 #include <map>
     28 #include <set>
     29 
     30 #include <base/logging.h>
     31 #include <base/strings/stringprintf.h>
     32 
     33 #include "update_engine/common/utils.h"
     34 #include "update_engine/payload_generator/extent_ranges.h"
     35 #include "update_engine/payload_generator/extent_utils.h"
     36 #include "update_engine/update_metadata.pb.h"
     37 
     38 using std::set;
     39 using std::string;
     40 using std::unique_ptr;
     41 using std::vector;
     42 
     43 namespace chromeos_update_engine {
     44 
     45 namespace {
     46 // Processes all blocks belonging to an inode and adds them to the extent list.
     47 // This function should match the prototype expected by ext2fs_block_iterate2().
     48 int ProcessInodeAllBlocks(ext2_filsys fs,
     49                           blk_t* blocknr,
     50                           e2_blkcnt_t blockcnt,
     51                           blk_t ref_blk,
     52                           int ref_offset,
     53                           void* priv) {
     54   vector<Extent>* extents = static_cast<vector<Extent>*>(priv);
     55   AppendBlockToExtents(extents, *blocknr);
     56   return 0;
     57 }
     58 
     59 // Processes only indirect, double indirect or triple indirect metadata
     60 // blocks belonging to an inode. This function should match the prototype of
     61 // ext2fs_block_iterate2().
     62 int AddMetadataBlocks(ext2_filsys fs,
     63                       blk_t* blocknr,
     64                       e2_blkcnt_t blockcnt,
     65                       blk_t ref_blk,
     66                       int ref_offset,
     67                       void* priv) {
     68   set<uint64_t>* blocks = static_cast<set<uint64_t>*>(priv);
     69   // If |blockcnt| is non-negative, |blocknr| points to the physical block
     70   // number.
     71   // If |blockcnt| is negative, it is one of the values: BLOCK_COUNT_IND,
     72   // BLOCK_COUNT_DIND, BLOCK_COUNT_TIND or BLOCK_COUNT_TRANSLATOR and
     73   // |blocknr| points to a block in the first three cases. The last case is
     74   // only used by GNU Hurd, so we shouldn't see those cases here.
     75   if (blockcnt == BLOCK_COUNT_IND || blockcnt == BLOCK_COUNT_DIND ||
     76       blockcnt == BLOCK_COUNT_TIND) {
     77     blocks->insert(*blocknr);
     78   }
     79   return 0;
     80 }
     81 
     82 struct UpdateFileAndAppendState {
     83   std::map<ext2_ino_t, FilesystemInterface::File>* inodes = nullptr;
     84   set<ext2_ino_t>* used_inodes = nullptr;
     85   vector<FilesystemInterface::File>* files = nullptr;
     86   ext2_filsys filsys;
     87 };
     88 
     89 int UpdateFileAndAppend(ext2_ino_t dir,
     90                         int entry,
     91                         struct ext2_dir_entry *dirent,
     92                         int offset,
     93                         int blocksize,
     94                         char *buf,
     95                         void *priv_data) {
     96   UpdateFileAndAppendState* state =
     97       static_cast<UpdateFileAndAppendState*>(priv_data);
     98   uint32_t file_type = dirent->name_len >> 8;
     99   // Directories can't have hard links, and they are added from the outer loop.
    100   if (file_type == EXT2_FT_DIR)
    101     return 0;
    102 
    103   auto ino_file = state->inodes->find(dirent->inode);
    104   if (ino_file == state->inodes->end())
    105     return 0;
    106   auto dir_file = state->inodes->find(dir);
    107   if (dir_file == state->inodes->end())
    108     return 0;
    109   string basename(dirent->name, dirent->name_len & 0xff);
    110   ino_file->second.name = dir_file->second.name;
    111   if (dir_file->second.name != "/")
    112     ino_file->second.name += "/";
    113   ino_file->second.name += basename;
    114 
    115   // Append this file to the output. If the file has a hard link, it will be
    116   // added twice to the output, but with different names, which is ok. That will
    117   // help identify all the versions of the same file.
    118   state->files->push_back(ino_file->second);
    119   state->used_inodes->insert(dirent->inode);
    120   return 0;
    121 }
    122 
    123 }  // namespace
    124 
    125 unique_ptr<Ext2Filesystem> Ext2Filesystem::CreateFromFile(
    126     const string& filename) {
    127   if (filename.empty())
    128     return nullptr;
    129   unique_ptr<Ext2Filesystem> result(new Ext2Filesystem());
    130   result->filename_ = filename;
    131 
    132   errcode_t err = ext2fs_open(filename.c_str(),
    133                               0,  // flags (read only)
    134                               0,  // superblock block number
    135                               0,  // block_size (autodetect)
    136                               unix_io_manager,
    137                               &result->filsys_);
    138   if (err) {
    139     LOG(ERROR) << "Opening ext2fs " << filename;
    140     return nullptr;
    141   }
    142   return result;
    143 }
    144 
    145 Ext2Filesystem::~Ext2Filesystem() {
    146   ext2fs_free(filsys_);
    147 }
    148 
    149 size_t Ext2Filesystem::GetBlockSize() const {
    150   return filsys_->blocksize;
    151 }
    152 
    153 size_t Ext2Filesystem::GetBlockCount() const {
    154   return ext2fs_blocks_count(filsys_->super);
    155 }
    156 
    157 bool Ext2Filesystem::GetFiles(vector<File>* files) const {
    158   TEST_AND_RETURN_FALSE_ERRCODE(ext2fs_read_inode_bitmap(filsys_));
    159 
    160   ext2_inode_scan iscan;
    161   TEST_AND_RETURN_FALSE_ERRCODE(
    162       ext2fs_open_inode_scan(filsys_, 0 /* buffer_blocks */, &iscan));
    163 
    164   std::map<ext2_ino_t, File> inodes;
    165 
    166   // List of directories. We need to first parse all the files in a directory
    167   // to later fix the absolute paths.
    168   vector<ext2_ino_t> directories;
    169 
    170   set<uint64_t> inode_blocks;
    171 
    172   // Iterator
    173   ext2_ino_t it_ino;
    174   ext2_inode it_inode;
    175 
    176   bool ok = true;
    177   while (true) {
    178     errcode_t error = ext2fs_get_next_inode(iscan, &it_ino, &it_inode);
    179     if (error) {
    180       LOG(ERROR) << "Failed to retrieve next inode (" << error << ")";
    181       ok = false;
    182       break;
    183     }
    184     if (it_ino == 0)
    185       break;
    186 
    187     // Skip inodes that are not in use.
    188     if (!ext2fs_test_inode_bitmap(filsys_->inode_map, it_ino))
    189       continue;
    190 
    191     File& file = inodes[it_ino];
    192     if (it_ino == EXT2_RESIZE_INO) {
    193       file.name = "<group-descriptors>";
    194     } else {
    195       file.name = base::StringPrintf("<inode-%u>", it_ino);
    196     }
    197 
    198     memset(&file.file_stat, 0, sizeof(file.file_stat));
    199     file.file_stat.st_ino = it_ino;
    200     file.file_stat.st_mode = it_inode.i_mode;
    201     file.file_stat.st_nlink = it_inode.i_links_count;
    202     file.file_stat.st_uid = it_inode.i_uid;
    203     file.file_stat.st_gid = it_inode.i_gid;
    204     file.file_stat.st_size = it_inode.i_size;
    205     file.file_stat.st_blksize = filsys_->blocksize;
    206     file.file_stat.st_blocks = it_inode.i_blocks;
    207     file.file_stat.st_atime = it_inode.i_atime;
    208     file.file_stat.st_mtime = it_inode.i_mtime;
    209     file.file_stat.st_ctime = it_inode.i_ctime;
    210 
    211     bool is_dir = (ext2fs_check_directory(filsys_, it_ino) == 0);
    212     if (is_dir)
    213       directories.push_back(it_ino);
    214 
    215     if (!ext2fs_inode_has_valid_blocks(&it_inode))
    216       continue;
    217 
    218     // Process the inode data and metadata blocks.
    219     // For normal files, inode blocks are indirect, double indirect
    220     // and triple indirect blocks (no data blocks). For directories and
    221     // the journal, all blocks are considered metadata blocks.
    222     int flags = it_ino < EXT2_GOOD_OLD_FIRST_INO ? 0 : BLOCK_FLAG_DATA_ONLY;
    223     error = ext2fs_block_iterate2(filsys_, it_ino, flags,
    224                                   nullptr,  // block_buf
    225                                   ProcessInodeAllBlocks,
    226                                   &file.extents);
    227 
    228     if (error) {
    229       LOG(ERROR) << "Failed to enumerate inode " << it_ino
    230                 << " blocks (" << error << ")";
    231       continue;
    232     }
    233     if (it_ino >= EXT2_GOOD_OLD_FIRST_INO) {
    234       ext2fs_block_iterate2(filsys_, it_ino, 0, nullptr,
    235                             AddMetadataBlocks,
    236                             &inode_blocks);
    237     }
    238   }
    239   ext2fs_close_inode_scan(iscan);
    240   if (!ok)
    241     return false;
    242 
    243   // The set of inodes already added to the output. There can be less elements
    244   // here than in files since the later can contain repeated inodes due to
    245   // hardlink files.
    246   set<ext2_ino_t> used_inodes;
    247 
    248   UpdateFileAndAppendState priv_data;
    249   priv_data.inodes = &inodes;
    250   priv_data.used_inodes = &used_inodes;
    251   priv_data.files = files;
    252   priv_data.filsys = filsys_;
    253 
    254   files->clear();
    255   // Iterate over all the files of each directory to update the name and add it.
    256   for (ext2_ino_t dir_ino : directories) {
    257     char* dir_name = nullptr;
    258     errcode_t error = ext2fs_get_pathname(filsys_, dir_ino, 0, &dir_name);
    259     if (error) {
    260       // Not being able to read a directory name is not a fatal error, it is
    261       // just skiped.
    262       LOG(WARNING) << "Reading directory name on inode " << dir_ino
    263                    << " (error " << error << ")";
    264       inodes[dir_ino].name = base::StringPrintf("<dir-%u>", dir_ino);
    265     } else {
    266       inodes[dir_ino].name = dir_name;
    267       files->push_back(inodes[dir_ino]);
    268       used_inodes.insert(dir_ino);
    269     }
    270     ext2fs_free_mem(&dir_name);
    271 
    272     error = ext2fs_dir_iterate2(
    273         filsys_, dir_ino, 0, nullptr /* block_buf */,
    274         UpdateFileAndAppend, &priv_data);
    275     if (error) {
    276       LOG(WARNING) << "Failed to enumerate files in directory "
    277                    << inodes[dir_ino].name << " (error " << error << ")";
    278     }
    279   }
    280 
    281   // Add <inode-blocks> file with the blocks that hold inodes.
    282   File inode_file;
    283   inode_file.name = "<inode-blocks>";
    284   for (uint64_t block : inode_blocks) {
    285     AppendBlockToExtents(&inode_file.extents, block);
    286   }
    287   files->push_back(inode_file);
    288 
    289   // Add <free-spacce> blocs.
    290   errcode_t error = ext2fs_read_block_bitmap(filsys_);
    291   if (error) {
    292     LOG(ERROR) << "Reading the blocks bitmap (error " << error << ")";
    293   } else {
    294     File free_space;
    295     free_space.name = "<free-space>";
    296     blk64_t blk_start = ext2fs_get_block_bitmap_start2(filsys_->block_map);
    297     blk64_t blk_end = ext2fs_get_block_bitmap_end2(filsys_->block_map);
    298     for (blk64_t block = blk_start; block < blk_end; block++) {
    299       if (!ext2fs_test_block_bitmap2(filsys_->block_map, block))
    300         AppendBlockToExtents(&free_space.extents, block);
    301     }
    302     files->push_back(free_space);
    303   }
    304 
    305   // Add all the unreachable files plus the pseudo-files with an inode. Since
    306   // these inodes aren't files in the filesystem, ignore the empty ones.
    307   for (const auto& ino_file : inodes) {
    308     if (used_inodes.find(ino_file.first) != used_inodes.end())
    309       continue;
    310     if (ino_file.second.extents.empty())
    311       continue;
    312 
    313     File file = ino_file.second;
    314     ExtentRanges ranges;
    315     ranges.AddExtents(file.extents);
    316     file.extents = ranges.GetExtentsForBlockCount(ranges.blocks());
    317 
    318     files->push_back(file);
    319   }
    320 
    321   return true;
    322 }
    323 
    324 bool Ext2Filesystem::LoadSettings(brillo::KeyValueStore* store) const {
    325   // First search for the settings inode following symlinks if we find some.
    326   ext2_ino_t ino_num = 0;
    327   errcode_t err = ext2fs_namei_follow(
    328       filsys_, EXT2_ROOT_INO /* root */, EXT2_ROOT_INO /* cwd */,
    329       "/etc/update_engine.conf", &ino_num);
    330   if (err != 0)
    331     return false;
    332 
    333   ext2_inode ino_data;
    334   if (ext2fs_read_inode(filsys_, ino_num, &ino_data) != 0)
    335     return false;
    336 
    337   // Load the list of blocks and then the contents of the inodes.
    338   vector<Extent> extents;
    339   err = ext2fs_block_iterate2(filsys_, ino_num, BLOCK_FLAG_DATA_ONLY,
    340                               nullptr,  // block_buf
    341                               ProcessInodeAllBlocks,
    342                               &extents);
    343   if (err != 0)
    344     return false;
    345 
    346   brillo::Blob blob;
    347   uint64_t physical_size = BlocksInExtents(extents) * filsys_->blocksize;
    348   // Sparse holes in the settings file are not supported.
    349   if (EXT2_I_SIZE(&ino_data) > physical_size)
    350     return false;
    351   if (!utils::ReadExtents(filename_, extents, &blob, physical_size,
    352                           filsys_->blocksize))
    353     return false;
    354 
    355   string text(blob.begin(), blob.begin() + EXT2_I_SIZE(&ino_data));
    356   return store->LoadFromString(text);
    357 }
    358 
    359 }  // namespace chromeos_update_engine
    360