libfstools/overlay.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/types.h>
  16 #include <sys/mount.h>
  17
  18 #include <asm/byteorder.h>
  19
  20 #include <errno.h>
  21 #include <string.h>
  22 #include <stdio.h>
  23 #include <unistd.h>
  24 #include <stdlib.h>
  25 #include <glob.h>
  26 #include <errno.h>
  27 #include <dirent.h>
  28 #include <fcntl.h>
  29
  30 #include "libfstools.h"
  31 #include "volume.h"
  32
  33 #ifndef GLOB_ONLYDIR
  34 #define GLOB_ONLYDIR 0x100
  35 #endif
  36
  37 #define SWITCH_JFFS2 "/tmp/.switch_jffs2"
  38
  39 static bool keep_sysupgrade;
  40
  41 static int
  42 handle_rmdir(const char *dir)
  43 {
  44         struct dirent *dt;
  45         struct stat st;
  46         DIR *d;
  47         int fd;
  48
  49         d = opendir(dir);
  50         if (!d)
  51                 return -1;
  52
  53         fd = dirfd(d);
  54
  55         while ((dt = readdir(d)) != NULL) {
  56                 if (fstatat(fd, dt->d_name, &st, AT_SYMLINK_NOFOLLOW) || S_ISDIR(st.st_mode))
  57                         continue;
  58
  59                 if (keep_sysupgrade && !strcmp(dt->d_name, "sysupgrade.tgz"))
  60                         continue;
  61
  62                 unlinkat(fd, dt->d_name, 0);
  63         }
  64
  65         closedir(d);
  66         rmdir(dir);
  67
  68         return 0;
  69 }
  70
  71 void
  72 foreachdir(const char *dir, int (*cb)(const char*))
  73 {
  74         static char *globdir = NULL;
  75         static size_t globdirlen = 0;
  76         struct stat s = { 0 };
  77         size_t dirlen = strlen(dir);
  78         glob_t gl;
  79         int j;
  80
  81         if (dirlen + sizeof("/*") > globdirlen) {
  82                 /* Alloc extra 256 B to avoid too many reallocs */
  83                 size_t len = dirlen + sizeof("/*") + 256;
  84                 char *tmp;
  85
  86                 tmp = realloc(globdir, len);
  87                 if (!tmp)
  88                         return;
  89                 globdir = tmp;
  90                 globdirlen = len;
  91         }
  92
  93         sprintf(globdir, "%s/*", dir);
  94
  95         /* Include GLOB_MARK as callbacks expect a trailing slash */
  96         if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
  97                 for (j = 0; j < gl.gl_pathc; j++) {
  98                         char *dir = gl.gl_pathv[j];
  99                         int len = strlen(gl.gl_pathv[j]);
 100                         int err;
 101
 102                         /* Quick way of skipping files */
 103                         if (dir[len - 1] != '/')
 104                                 continue;
 105
 106                         /* lstat needs path without a trailing slash */
 107                         if (len > 1)
 108                                 dir[len - 1] = '\0';
 109                         err = lstat(gl.gl_pathv[j], &s);
 110                         if (len > 1)
 111                                 dir[len - 1] = '/';
 112
 113                         if (!err && !S_ISLNK(s.st_mode))
 114                                 foreachdir(gl.gl_pathv[j], cb);
 115         }
 116         cb(dir);
 117 }
 118
 119 static void foreach_mount(int (*cb)(const char *, const char *))
 120 {
 121         FILE *fp = fopen("/proc/mounts", "r");
 122         static char line[256];
 123
 124         if (!fp)
 125                 return;
 126
 127         while (fgets(line, sizeof(line), fp)) {
 128                 char device[32], mount_point[32];
 129
 130                 if (sscanf(line, "%31s %31s %*s %*s %*u %*u", device, mount_point) == 2)
 131                         cb(device, mount_point);
 132         }
 133
 134         fclose(fp);
 135 }
 136
 137 void
 138 overlay_delete(const char *dir, bool _keep_sysupgrade)
 139 {
 140         keep_sysupgrade = _keep_sysupgrade;
 141         foreachdir(dir, handle_rmdir);
 142 }
 143
 144 static int
 145 overlay_mount(struct volume *v, char *fs)
 146 {
 147         if (mkdir("/tmp/overlay", 0755)) {
 148                 ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
 149                 return -1;
 150         }
 151
 152         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 153                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n", fs, v->blk);
 154                 return -1;
 155         }
 156
 157         return 0;
 158 }
 159
 160 /**
 161  * move_mount - move mount point to the new root
 162  */
 163 static int move_mount(const char *device, const char *mount_point)
 164 {
 165         static const char *prefix = "/tmp/root/";
 166
 167         if (strncmp(mount_point, prefix, strlen(prefix)))
 168                 return 0;
 169
 170         return mount_move(prefix, "/", mount_point + strlen(prefix));
 171 }
 172
 173 static int
 174 switch2jffs(struct volume *v)
 175 {
 176         struct stat s;
 177         int ret;
 178
 179         if (!stat(SWITCH_JFFS2, &s)) {
 180                 ULOG_ERR("jffs2 switch already running\n");
 181                 return -1;
 182         }
 183
 184         creat("/tmp/.switch_jffs2", 0600);
 185         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 186         unlink("/tmp/.switch_jffs2");
 187         if (ret) {
 188                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %m\n", v->blk);
 189                 return -1;
 190         }
 191
 192         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 193                 ULOG_ERR("failed - mount -o remount,ro none: %m\n");
 194                 return -1;
 195         }
 196
 197         if (system("cp -a /tmp/root/* /rom/overlay")) {
 198                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %m\n");
 199                 return -1;
 200         }
 201
 202         if (pivot("/rom", "/mnt")) {
 203                 ULOG_ERR("failed - pivot /rom /mnt: %m\n");
 204                 return -1;
 205         }
 206
 207         if (mount_move("/mnt", "/tmp/root", "")) {
 208                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %m\n");
 209                 return -1;
 210         }
 211
 212         ret = fopivot("/overlay", "/rom");
 213
 214         /*
 215          * Besides copying overlay data from "tmpfs" to "jffs2" we should also
 216          * move mount points that user could create during JFFS2 formatting.
 217          * This has to happen after fopivot call because:
 218          * 1) It's trivial to find mount points to move then (/tmp/root/...).
 219          * 2) We can't do that earlier using /rom/overlay/upper/ as overlay(fs)
 220          *    doesn't support mounts. Mounting to upper dir don't make overlay
 221          *    /propagate/ files to the target dir.
 222          */
 223         foreach_mount(move_mount);
 224
 225         return ret;
 226 }
 227
 228 int
 229 handle_whiteout(const char *dir)
 230 {
 231         struct stat s;
 232         char link[256];
 233         ssize_t sz;
 234         struct dirent **namelist;
 235         int n;
 236
 237         n = scandir(dir, &namelist, NULL, NULL);
 238
 239         if (n < 1)
 240                 return -1;
 241
 242         while (n--) {
 243                 char file[256];
 244
 245                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 246                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 247                         sz = readlink(file, link, sizeof(link) - 1);
 248                         if (sz > 0) {
 249                                 char *orig;
 250
 251                                 link[sz] = '\0';
 252                                 orig = strstr(&file[1], "/");
 253                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 254                                         unlink(orig);
 255                         }
 256                 }
 257                 free(namelist[n]);
 258         }
 259         free(namelist);
 260
 261         return 0;
 262 }
 263
 264 static char *overlay_fs_name(int type)
 265 {
 266         switch (type) {
 267                 case FS_EXT4:
 268                         return "ext4";
 269                 case FS_F2FS:
 270                         return "f2fs";
 271                 case FS_UBIFS:
 272                         return "ubifs";
 273                 case FS_JFFS2:
 274                 default:
 275                         return "jffs2";
 276         }
 277 }
 278
 279 int
 280 jffs2_switch(struct volume *v)
 281 {
 282         char *mp, *fs_name;
 283         int type;
 284
 285         if (find_overlay_mount("overlayfs:/tmp/root"))
 286                 return -1;
 287
 288         if (find_filesystem("overlay")) {
 289                 ULOG_ERR("overlayfs not supported by kernel\n");
 290                 return -1;
 291         }
 292
 293         volume_init(v);
 294         mp = find_mount_point(v->blk, 0);
 295         if (mp) {
 296                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 297                 return -1;
 298         }
 299
 300         type = volume_identify(v);
 301         fs_name = overlay_fs_name(type);
 302
 303         switch (type) {
 304         case FS_NONE:
 305                 ULOG_ERR("no jffs2 marker found\n");
 306                 /* fall through */
 307
 308         case FS_DEADCODE:
 309                 if (switch2jffs(v))
 310                         return -1;
 311
 312                 ULOG_INFO("performing overlay whiteout\n");
 313                 umount2("/tmp/root", MNT_DETACH);
 314                 foreachdir("/overlay/", handle_whiteout);
 315
 316                 /* try hard to be in sync */
 317                 ULOG_INFO("syncronizing overlay\n");
 318                 if (system("cp -a /tmp/root/upper/* / 2>/dev/null"))
 319                         ULOG_ERR("failed to sync jffs2 overlay\n");
 320                 break;
 321
 322         case FS_EXT4:
 323         case FS_F2FS:
 324         case FS_UBIFS:
 325                 if (overlay_mount(v, fs_name))
 326                         return -1;
 327                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 328                         ULOG_ERR("switching to %s failed\n", fs_name);
 329                         return -1;
 330                 }
 331                 break;
 332         }
 333
 334         sync();
 335         fs_state_set("/overlay", FS_STATE_READY);
 336         return 0;
 337 }
 338
 339 static int overlay_mount_fs(struct volume *v)
 340 {
 341         char *fstype = overlay_fs_name(volume_identify(v));
 342
 343         if (mkdir("/tmp/overlay", 0755)) {
 344                 ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
 345                 return -1;
 346         }
 347
 348         if (mount(v->blk, "/tmp/overlay", fstype,
 349 #ifdef OVL_MOUNT_FULL_ACCESS_TIME
 350                 MS_RELATIME,
 351 #else
 352                 MS_NOATIME,
 353 #endif
 354 #ifdef OVL_MOUNT_COMPRESS_ZLIB
 355                 "compr=zlib"
 356 #else
 357                 NULL
 358 #endif
 359                 )) {
 360                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n",
 361                          fstype, v->blk);
 362                 return -1;
 363         }
 364
 365         return 0;
 366 }
 367
 368 enum fs_state fs_state_get(const char *dir)
 369 {
 370         char *path;
 371         char valstr[16];
 372         uint32_t val;
 373         ssize_t len;
 374
 375         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 376         sprintf(path, "%s/.fs_state", dir);
 377         len = readlink(path, valstr, sizeof(valstr) - 1);
 378         if (len < 0)
 379                 return FS_STATE_UNKNOWN;
 380
 381         valstr[len] = 0;
 382         val = atoi(valstr);
 383
 384         if (val > __FS_STATE_LAST)
 385                 return FS_STATE_UNKNOWN;
 386
 387         return val;
 388 }
 389
 390
 391 int fs_state_set(const char *dir, enum fs_state state)
 392 {
 393         char valstr[16];
 394         char *path;
 395
 396         if (fs_state_get(dir) == state)
 397                 return 0;
 398
 399         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 400         sprintf(path, "%s/.fs_state", dir);
 401         unlink(path);
 402         snprintf(valstr, sizeof(valstr), "%d", state);
 403
 404         return symlink(valstr, path);
 405 }
 406
 407
 408 int mount_overlay(struct volume *v)
 409 {
 410         char *mp, *fs_name;
 411
 412         if (!v)
 413                 return -1;
 414
 415         mp = find_mount_point(v->blk, 0);
 416         if (mp) {
 417                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 418                 return -1;
 419         }
 420
 421         overlay_mount_fs(v);
 422
 423         extroot_prefix = "/tmp/overlay";
 424         if (!mount_extroot()) {
 425                 ULOG_INFO("switched to extroot\n");
 426                 return 0;
 427         }
 428
 429         switch(fs_state_get("/tmp/overlay")) {
 430         case FS_STATE_UNKNOWN:
 431                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 432                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 433                         ULOG_ERR("unable to set filesystem state\n");
 434                         break;
 435                 }
 436         case FS_STATE_PENDING:
 437                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 438                 overlay_delete("/tmp/overlay", true);
 439                 break;
 440         case FS_STATE_READY:
 441                 break;
 442         }
 443
 444         fs_name = overlay_fs_name(volume_identify(v));
 445         ULOG_INFO("switching to %s overlay\n", fs_name);
 446         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 447                 ULOG_ERR("switching to %s failed - fallback to ramoverlay\n", fs_name);
 448                 return ramoverlay();
 449         }
 450
 451         return -1;
 452 }