libfstools/snapshot.c

   1 /*
   2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License version 2.1
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <sys/stat.h>
  15 #include <sys/stat.h>
  16 #include <sys/types.h>
  17 #include <sys/ioctl.h>
  18 #include <sys/mount.h>
  19 #include <mtd/mtd-user.h>
  20
  21 #include <glob.h>
  22 #include <fcntl.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <libgen.h>
  26 #include <unistd.h>
  27 #include <string.h>
  28
  29 #include <libubox/list.h>
  30 #include <libubox/blob.h>
  31 #include <libubox/md5.h>
  32
  33 #include "libfstools.h"
  34 #include "volume.h"
  35 #include "snapshot.h"
  36
  37 int
  38 verify_file_hash(char *file, uint32_t *hash)
  39 {
  40         uint32_t md5[4];
  41
  42         if (md5sum(file, md5)) {
  43                 fprintf(stderr, "failed to generate md5 sum\n");
  44                 return -1;
  45         }
  46
  47         if (memcmp(md5, hash, sizeof(md5))) {
  48                 fprintf(stderr, "failed to verify hash of %s.\n", file);
  49                 return -1;
  50         }
  51
  52         return 0;
  53 }
  54
  55 int
  56 snapshot_next_free(struct volume *v, uint32_t *seq)
  57 {
  58         struct file_header hdr = { 0 };
  59         int block = 0;
  60
  61         *seq = rand();
  62
  63         do {
  64                 if (volume_read(v, &hdr, block * v->block_size, sizeof(struct file_header))) {
  65                         fprintf(stderr, "scanning for next free block failed\n");
  66                         return 0;
  67                 }
  68
  69                 be32_to_hdr(&hdr);
  70
  71                 if (hdr.magic != OWRT)
  72                         break;
  73
  74                 if (hdr.type == DATA && !valid_file_size(hdr.length)) {
  75                         if (*seq + 1 != hdr.seq && block)
  76                                 return block;
  77                         *seq = hdr.seq;
  78                         block += pad_file_size(v, hdr.length) / v->block_size;
  79                 }
  80         } while (hdr.type == DATA);
  81
  82         return block;
  83 }
  84
  85 int
  86 config_find(struct volume *v, struct file_header *conf, struct file_header *sentinel)
  87 {
  88         uint32_t seq;
  89         int i, next = snapshot_next_free(v, &seq);
  90
  91         conf->magic = sentinel->magic = 0;
  92
  93         if (!volume_read(v, conf, next, sizeof(*conf)))
  94                 be32_to_hdr(conf);
  95
  96         for (i = (v->size / v->block_size) - 1; i > 0; i--) {
  97                 if (volume_read(v, sentinel,  i * v->block_size, sizeof(*sentinel))) {
  98                         fprintf(stderr, "failed to read header\n");
  99                         return -1;
 100                 }
 101                 be32_to_hdr(sentinel);
 102
 103                 if (sentinel->magic == OWRT && sentinel->type == CONF && !valid_file_size(sentinel->length)) {
 104                         if (next == i)
 105                                 return -1;
 106                         return i;
 107                 }
 108         }
 109
 110         return -1;
 111 }
 112
 113 int
 114 snapshot_write_file(struct volume *v, int block, char *file, uint32_t seq, uint32_t type)
 115 {
 116         uint32_t md5[4] = { 0 };
 117         struct file_header hdr;
 118         struct stat s;
 119         char buffer[256];
 120         int in = 0, len, offset;
 121         int ret = -1;
 122
 123         if (stat(file, &s) || md5sum(file, md5)) {
 124                 fprintf(stderr, "stat failed on %s\n", file);
 125                 goto out;
 126         }
 127
 128         if ((block * v->block_size) + pad_file_size(v, s.st_size) > v->size) {
 129                 fprintf(stderr, "upgrade is too big for the flash\n");
 130                 goto out;
 131         }
 132         volume_erase(v, block * v->block_size, pad_file_size(v, s.st_size));
 133         volume_erase(v, block * v->block_size + pad_file_size(v, s.st_size), v->block_size);
 134
 135         hdr.length = s.st_size;
 136         hdr.magic = OWRT;
 137         hdr.type = type;
 138         hdr.seq = seq;
 139         memcpy(hdr.md5, md5, sizeof(md5));
 140         hdr_to_be32(&hdr);
 141
 142         if (volume_write(v, &hdr, block * v->block_size, sizeof(struct file_header))) {
 143                 fprintf(stderr, "failed to write header\n");
 144                 goto out;
 145         }
 146
 147         in = open(file, O_RDONLY);
 148         if (in < 1) {
 149                 fprintf(stderr, "failed to open %s\n", file);
 150                 goto out;
 151         }
 152
 153         offset = (block * v->block_size) + sizeof(struct file_header);
 154
 155         while ((len = read(in, buffer, sizeof(buffer))) > 0) {
 156                 if (volume_write(v, buffer, offset, len) < 0)
 157                         goto out;
 158                 offset += len;
 159         }
 160
 161         ret = 0;
 162
 163 out:
 164         if (in > 0)
 165                 close(in);
 166
 167         return ret;
 168 }
 169
 170 int
 171 snapshot_read_file(struct volume *v, int block, char *file, uint32_t type)
 172 {
 173         struct file_header hdr;
 174         char buffer[256];
 175         int out, offset = 0;
 176
 177         if (volume_read(v, &hdr, block * v->block_size, sizeof(struct file_header))) {
 178                 fprintf(stderr, "failed to read header\n");
 179                 return -1;
 180         }
 181         be32_to_hdr(&hdr);
 182
 183         if (hdr.magic != OWRT)
 184                 return -1;
 185
 186         if (hdr.type != type)
 187                 return -1;
 188
 189         if (valid_file_size(hdr.length))
 190                 return -1;
 191
 192         out = open(file, O_WRONLY | O_CREAT, 0700);
 193         if (!out) {
 194                 fprintf(stderr, "failed to open %s\n", file);
 195                 return -1;
 196         }
 197
 198         offset = block * v->block_size + sizeof(hdr);
 199
 200         while (hdr.length > 0) {
 201                 int len = sizeof(buffer);
 202
 203                 if (hdr.length < len)
 204                         len = hdr.length;
 205
 206                 if (volume_read(v, buffer, offset, len))
 207                         return -1;
 208                 if (write(out, buffer, len) != len)
 209                         return -1;
 210                 offset += len;
 211                 hdr.length -= len;
 212         }
 213
 214         close(out);
 215
 216         if (verify_file_hash(file, hdr.md5)) {
 217                 fprintf(stderr, "md5 verification failed\n");
 218                 unlink(file);
 219                 return 0;
 220         }
 221
 222         block += pad_file_size(v, hdr.length) / v->block_size;
 223
 224         return block;
 225 }
 226
 227 int
 228 sentinel_write(struct volume *v, uint32_t _seq)
 229 {
 230         int ret, block;
 231         struct stat s;
 232         uint32_t seq;
 233
 234         if (stat("/tmp/config.tar.gz", &s)) {
 235                 fprintf(stderr, "failed to stat /tmp/config.tar.gz\n");
 236                 return -1;
 237         }
 238
 239         snapshot_next_free(v, &seq);
 240         if (_seq)
 241                 seq = _seq;
 242         block = v->size / v->block_size;
 243         block -= pad_file_size(v, s.st_size) / v->block_size;
 244         if (block < 0)
 245                 block = 0;
 246
 247         ret = snapshot_write_file(v, block, "/tmp/config.tar.gz", seq, CONF);
 248         if (ret)
 249                 fprintf(stderr, "failed to write sentinel\n");
 250         else
 251                 fprintf(stderr, "wrote /tmp/config.tar.gz sentinel\n");
 252         return ret;
 253 }
 254
 255 int
 256 volatile_write(struct volume *v, uint32_t _seq)
 257 {
 258         int block, ret;
 259         uint32_t seq;
 260
 261         block = snapshot_next_free(v, &seq);
 262         if (_seq)
 263                 seq = _seq;
 264         if (block < 0)
 265                 block = 0;
 266
 267         ret = snapshot_write_file(v, block, "/tmp/config.tar.gz", seq, CONF);
 268         if (ret)
 269                 fprintf(stderr, "failed to write /tmp/config.tar.gz\n");
 270         else
 271                 fprintf(stderr, "wrote /tmp/config.tar.gz\n");
 272         return ret;
 273 }
 274
 275 static int
 276 snapshot_sync(void)
 277 {
 278         struct volume *v = volume_find("rootfs_data");
 279         struct file_header sentinel, conf;
 280         int next, block = 0;
 281         uint32_t seq;
 282
 283         if (!v)
 284                 return -1;
 285
 286         next = snapshot_next_free(v, &seq);
 287         block = config_find(v, &conf, &sentinel);
 288         if (is_config(&conf) && conf.seq != seq) {
 289                 conf.magic = 0;
 290                 volume_erase(v, next * v->block_size, 2 * v->block_size);
 291         }
 292
 293         if (is_config(&sentinel) && (sentinel.seq != seq)) {
 294                 sentinel.magic = 0;
 295                 volume_erase(v, block * v->block_size, v->block_size);
 296         }
 297
 298         if (!is_config(&conf) && !is_config(&sentinel)) {
 299         //      fprintf(stderr, "no config found\n");
 300         } else if (((is_config(&conf) && is_config(&sentinel)) &&
 301                                 (memcmp(conf.md5, sentinel.md5, sizeof(conf.md5)) || (conf.seq != sentinel.seq))) ||
 302                         (is_config(&conf) && !is_config(&sentinel))) {
 303                 uint32_t seq;
 304                 int next = snapshot_next_free(v, &seq);
 305                 int ret = snapshot_read_file(v, next, "/tmp/config.tar.gz", CONF);
 306                 if (ret > 0) {
 307                         if (sentinel_write(v, conf.seq))
 308                                 fprintf(stderr, "failed to write sentinel data");
 309                 }
 310         } else if (!is_config(&conf) && is_config(&sentinel) && next) {
 311                 int ret = snapshot_read_file(v, block, "/tmp/config.tar.gz", CONF);
 312                 if (ret > 0)
 313                         if (volatile_write(v, sentinel.seq))
 314                                 fprintf(stderr, "failed to write sentinel data");
 315         } else
 316                 fprintf(stderr, "config in sync\n");
 317
 318         unlink("/tmp/config.tar.gz");
 319
 320         return 0;
 321 }
 322
 323 static int
 324 _ramoverlay(char *rom, char *overlay)
 325 {
 326         mount("tmpfs", overlay, "tmpfs", MS_NOATIME, "mode=0755");
 327         return fopivot(overlay, rom);
 328 }
 329
 330 int
 331 mount_snapshot(void)
 332 {
 333         snapshot_sync();
 334         setenv("SNAPSHOT", "magic", 1);
 335         _ramoverlay("/rom", "/overlay");
 336         system("/sbin/snapshot unpack");
 337         foreachdir("/overlay/", handle_whiteout);
 338         mkdir("/volatile", 0700);
 339         _ramoverlay("/rom", "/volatile");
 340         mount_move("/rom/volatile", "/volatile", "");
 341         mount_move("/rom/rom", "/rom", "");
 342         system("/sbin/snapshot config_unpack");
 343         foreachdir("/volatile/", handle_whiteout);
 344         unsetenv("SNAPSHOT");
 345         return -1;
 346 }