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 #define SWITCH_JFFS2 "/tmp/.switch_jffs2"
  34
  35 static bool keep_sysupgrade;
  36
  37 static int
  38 handle_rmdir(const char *dir)
  39 {
  40         struct dirent *dt;
  41         struct stat st;
  42         DIR *d;
  43         int fd;
  44
  45         d = opendir(dir);
  46         if (!d)
  47                 return -1;
  48
  49         fd = dirfd(d);
  50
  51         while ((dt = readdir(d)) != NULL) {
  52                 if (fstatat(fd, dt->d_name, &st, AT_SYMLINK_NOFOLLOW) || S_ISDIR(st.st_mode))
  53                         continue;
  54
  55                 if (keep_sysupgrade && !strcmp(dt->d_name, "sysupgrade.tgz"))
  56                         continue;
  57
  58                 unlinkat(fd, dt->d_name, 0);
  59         }
  60
  61         closedir(d);
  62         rmdir(dir);
  63
  64         return 0;
  65 }
  66
  67 void
  68 foreachdir(const char *dir, int (*cb)(const char*))
  69 {
  70         static char *globdir = NULL;
  71         static size_t globdirlen = 0;
  72         struct stat s = { 0 };
  73         size_t dirlen = strlen(dir);
  74         glob_t gl;
  75         int j;
  76
  77         if (dirlen + sizeof("/*") > globdirlen) {
  78                 /* Alloc extra 256 B to avoid too many reallocs */
  79                 size_t len = dirlen + sizeof("/*") + 256;
  80                 char *tmp;
  81
  82                 tmp = realloc(globdir, len);
  83                 if (!tmp)
  84                         return;
  85                 globdir = tmp;
  86                 globdirlen = len;
  87         }
  88
  89         if (dir[dirlen - 1] == '/')
  90                 sprintf(globdir, "%s*", dir);
  91         else
  92                 sprintf(globdir, "%s/*", dir);
  93
  94         /* Include GLOB_MARK as callbacks expect a trailing slash */
  95         if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
  96                 for (j = 0; j < gl.gl_pathc; j++) {
  97                         char *dir = gl.gl_pathv[j];
  98                         int len = strlen(gl.gl_pathv[j]);
  99                         int err;
 100
 101                         /* Quick way of skipping files */
 102                         if (dir[len - 1] != '/')
 103                                 continue;
 104
 105                         /* lstat needs path without a trailing slash */
 106                         if (len > 1)
 107                                 dir[len - 1] = '\0';
 108                         err = lstat(gl.gl_pathv[j], &s);
 109                         if (len > 1)
 110                                 dir[len - 1] = '/';
 111
 112                         if (!err && !S_ISLNK(s.st_mode))
 113                                 foreachdir(gl.gl_pathv[j], cb);
 114         }
 115         cb(dir);
 116 }
 117
 118 void
 119 overlay_delete(const char *dir, bool _keep_sysupgrade)
 120 {
 121         keep_sysupgrade = _keep_sysupgrade;
 122         foreachdir(dir, handle_rmdir);
 123 }
 124
 125 static int
 126 overlay_mount(struct volume *v, char *fs)
 127 {
 128         if (mkdir("/tmp/overlay", 0755)) {
 129                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 130                 return -1;
 131         }
 132
 133         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 134                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n", fs, v->blk, strerror(errno));
 135                 return -1;
 136         }
 137
 138         return 0;
 139 }
 140
 141 static int
 142 switch2jffs(struct volume *v)
 143 {
 144         struct stat s;
 145         int ret;
 146
 147         if (!stat(SWITCH_JFFS2, &s)) {
 148                 ULOG_ERR("jffs2 switch already running\n");
 149                 return -1;
 150         }
 151
 152         creat("/tmp/.switch_jffs2", 0600);
 153         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 154         unlink("/tmp/.switch_jffs2");
 155         if (ret) {
 156                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %s\n", v->blk, strerror(errno));
 157                 return -1;
 158         }
 159
 160         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 161                 ULOG_ERR("failed - mount -o remount,ro none: %s\n", strerror(errno));
 162                 return -1;
 163         }
 164
 165         if (system("cp -a /tmp/root/* /rom/overlay")) {
 166                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %s\n", strerror(errno));
 167                 return -1;
 168         }
 169
 170         if (pivot("/rom", "/mnt")) {
 171                 ULOG_ERR("failed - pivot /rom /mnt: %s\n", strerror(errno));
 172                 return -1;
 173         }
 174
 175         if (mount_move("/mnt", "/tmp/root", "")) {
 176                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
 177                 return -1;
 178         }
 179
 180         return fopivot("/overlay", "/rom");
 181 }
 182
 183 int
 184 handle_whiteout(const char *dir)
 185 {
 186         struct stat s;
 187         char link[256];
 188         ssize_t sz;
 189         struct dirent **namelist;
 190         int n;
 191
 192         n = scandir(dir, &namelist, NULL, NULL);
 193
 194         if (n < 1)
 195                 return -1;
 196
 197         while (n--) {
 198                 char file[256];
 199
 200                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 201                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 202                         sz = readlink(file, link, sizeof(link) - 1);
 203                         if (sz > 0) {
 204                                 char *orig;
 205
 206                                 link[sz] = '\0';
 207                                 orig = strstr(&file[1], "/");
 208                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 209                                         unlink(orig);
 210                         }
 211                 }
 212                 free(namelist[n]);
 213         }
 214         free(namelist);
 215
 216         return 0;
 217 }
 218
 219 static char *overlay_fs_name(int type)
 220 {
 221         switch (type) {
 222                 case FS_EXT4:
 223                         return "ext4";
 224                 case FS_F2FS:
 225                         return "f2fs";
 226                 case FS_UBIFS:
 227                         return "ubifs";
 228                 case FS_JFFS2:
 229                 default:
 230                         return "jffs2";
 231         }
 232 }
 233
 234 int
 235 jffs2_switch(struct volume *v)
 236 {
 237         char *mp, *fs_name;
 238         int type;
 239
 240         if (find_overlay_mount("overlayfs:/tmp/root"))
 241                 return -1;
 242
 243         if (find_filesystem("overlay")) {
 244                 ULOG_ERR("overlayfs not supported by kernel\n");
 245                 return -1;
 246         }
 247
 248         volume_init(v);
 249         mp = find_mount_point(v->blk, 0);
 250         if (mp) {
 251                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 252                 return -1;
 253         }
 254
 255         type = volume_identify(v);
 256         fs_name = overlay_fs_name(type);
 257
 258         switch (type) {
 259         case FS_NONE:
 260                 ULOG_ERR("no jffs2 marker found\n");
 261                 /* fall through */
 262
 263         case FS_DEADCODE:
 264                 if (switch2jffs(v))
 265                         return -1;
 266
 267                 ULOG_INFO("performing overlay whiteout\n");
 268                 umount2("/tmp/root", MNT_DETACH);
 269                 foreachdir("/overlay/", handle_whiteout);
 270                 break;
 271
 272         case FS_EXT4:
 273         case FS_F2FS:
 274         case FS_UBIFS:
 275                 if (overlay_mount(v, fs_name))
 276                         return -1;
 277                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 278                         ULOG_ERR("switching to %s failed\n", fs_name);
 279                         return -1;
 280                 }
 281                 break;
 282         }
 283
 284         sync();
 285         fs_state_set("/overlay", FS_STATE_READY);
 286         return 0;
 287 }
 288
 289 static int overlay_mount_fs(struct volume *v)
 290 {
 291         char *fstype = overlay_fs_name(volume_identify(v));
 292
 293         if (mkdir("/tmp/overlay", 0755)) {
 294                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 295                 return -1;
 296         }
 297
 298         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 299                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
 300                          fstype, v->blk, strerror(errno));
 301                 return -1;
 302         }
 303
 304         return 0;
 305 }
 306
 307 enum fs_state fs_state_get(const char *dir)
 308 {
 309         char *path;
 310         char valstr[16];
 311         uint32_t val;
 312         ssize_t len;
 313
 314         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 315         sprintf(path, "%s/.fs_state", dir);
 316         len = readlink(path, valstr, sizeof(valstr) - 1);
 317         if (len < 0)
 318                 return FS_STATE_UNKNOWN;
 319
 320         valstr[len] = 0;
 321         val = atoi(valstr);
 322
 323         if (val > __FS_STATE_LAST)
 324                 return FS_STATE_UNKNOWN;
 325
 326         return val;
 327 }
 328
 329
 330 int fs_state_set(const char *dir, enum fs_state state)
 331 {
 332         char valstr[16];
 333         char *path;
 334
 335         if (fs_state_get(dir) == state)
 336                 return 0;
 337
 338         path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
 339         sprintf(path, "%s/.fs_state", dir);
 340         unlink(path);
 341         snprintf(valstr, sizeof(valstr), "%d", state);
 342
 343         return symlink(valstr, path);
 344 }
 345
 346
 347 int mount_overlay(struct volume *v)
 348 {
 349         char *mp, *fs_name;
 350
 351         if (!v)
 352                 return -1;
 353
 354         mp = find_mount_point(v->blk, 0);
 355         if (mp) {
 356                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 357                 return -1;
 358         }
 359
 360         overlay_mount_fs(v);
 361
 362         extroot_prefix = "/tmp/overlay";
 363         if (!mount_extroot()) {
 364                 ULOG_INFO("switched to extroot\n");
 365                 return 0;
 366         }
 367
 368         switch(fs_state_get("/tmp/overlay")) {
 369         case FS_STATE_UNKNOWN:
 370                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 371                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 372                         ULOG_ERR("unable to set filesystem state\n");
 373                         break;
 374                 }
 375         case FS_STATE_PENDING:
 376                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 377                 overlay_delete("/tmp/overlay", true);
 378                 break;
 379         case FS_STATE_READY:
 380                 break;
 381         }
 382
 383         fs_name = overlay_fs_name(volume_identify(v));
 384         ULOG_INFO("switching to %s overlay\n", fs_name);
 385         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 386                 ULOG_ERR("switching to %s failed - fallback to ramoverlay\n", fs_name);
 387                 return ramoverlay();
 388         }
 389
 390         return -1;
 391 }