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 #include <sys/syscall.h>
  18
  19 #include <asm/byteorder.h>
  20
  21 #include <errno.h>
  22 #include <string.h>
  23 #include <stdio.h>
  24 #include <unistd.h>
  25 #include <stdlib.h>
  26 #include <glob.h>
  27 #include <errno.h>
  28 #include <dirent.h>
  29 #include <fcntl.h>
  30
  31 #include "libfstools.h"
  32 #include "volume.h"
  33
  34 #define SWITCH_JFFS2 "/tmp/.switch_jffs2"
  35
  36 static bool keep_sysupgrade;
  37
  38 static ssize_t
  39 fs_getxattr(const char *path, const char *name, void *value, size_t size)
  40 {
  41         return syscall(__NR_getxattr, path, name, value, size);
  42 }
  43
  44 static ssize_t
  45 fs_setxattr(const char *path, const char *name, const void *value, size_t size, int flags)
  46 {
  47         return syscall(__NR_setxattr, path, name, value, size, flags);
  48 }
  49
  50 static int
  51 handle_rmdir(const char *dir)
  52 {
  53         struct dirent *dt;
  54         struct stat st;
  55         DIR *d;
  56         int fd;
  57
  58         d = opendir(dir);
  59         if (!d)
  60                 return -1;
  61
  62         fd = dirfd(d);
  63
  64         while ((dt = readdir(d)) != NULL) {
  65                 if (fstatat(fd, dt->d_name, &st, AT_SYMLINK_NOFOLLOW) || S_ISDIR(st.st_mode))
  66                         continue;
  67
  68                 if (keep_sysupgrade && !strcmp(dt->d_name, "sysupgrade.tgz"))
  69                         continue;
  70
  71                 unlinkat(fd, dt->d_name, 0);
  72         }
  73
  74         closedir(d);
  75         rmdir(dir);
  76
  77         return 0;
  78 }
  79
  80 void
  81 foreachdir(const char *dir, int (*cb)(const char*))
  82 {
  83         char globdir[256];
  84         glob_t gl;
  85         int j;
  86
  87         if (dir[strlen(dir) - 1] == '/')
  88                 snprintf(globdir, 256, "%s*", dir);
  89         else
  90                 snprintf(globdir, 256, "%s/*", dir); /**/
  91
  92         if (!glob(globdir, GLOB_NOESCAPE | GLOB_MARK | GLOB_ONLYDIR, NULL, &gl))
  93                 for (j = 0; j < gl.gl_pathc; j++)
  94                         foreachdir(gl.gl_pathv[j], cb);
  95
  96         cb(dir);
  97 }
  98
  99 void
 100 overlay_delete(const char *dir, bool _keep_sysupgrade)
 101 {
 102         keep_sysupgrade = _keep_sysupgrade;
 103         foreachdir(dir, handle_rmdir);
 104 }
 105
 106 static int
 107 overlay_mount(struct volume *v, char *fs)
 108 {
 109         if (mkdir("/tmp/overlay", 0755)) {
 110                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 111                 return -1;
 112         }
 113
 114         if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
 115                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n", fs, v->blk, strerror(errno));
 116                 return -1;
 117         }
 118
 119         return volume_init(v);
 120 }
 121
 122 static int
 123 switch2jffs(struct volume *v)
 124 {
 125         struct stat s;
 126         int ret;
 127
 128         if (!stat(SWITCH_JFFS2, &s)) {
 129                 ULOG_ERR("jffs2 switch already running\n");
 130                 return -1;
 131         }
 132
 133         creat("/tmp/.switch_jffs2", 0600);
 134         ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
 135         unlink("/tmp/.switch_jffs2");
 136         if (ret) {
 137                 ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %s\n", v->blk, strerror(errno));
 138                 return -1;
 139         }
 140
 141         if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
 142                 ULOG_ERR("failed - mount -o remount,ro none: %s\n", strerror(errno));
 143                 return -1;
 144         }
 145
 146         if (system("cp -a /tmp/root/* /rom/overlay")) {
 147                 ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %s\n", strerror(errno));
 148                 return -1;
 149         }
 150
 151         if (pivot("/rom", "/mnt")) {
 152                 ULOG_ERR("failed - pivot /rom /mnt: %s\n", strerror(errno));
 153                 return -1;
 154         }
 155
 156         if (mount_move("/mnt", "/tmp/root", "")) {
 157                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
 158                 return -1;
 159         }
 160
 161         return fopivot("/overlay", "/rom");
 162 }
 163
 164 int
 165 handle_whiteout(const char *dir)
 166 {
 167         struct stat s;
 168         char link[256];
 169         ssize_t sz;
 170         struct dirent **namelist;
 171         int n;
 172
 173         n = scandir(dir, &namelist, NULL, NULL);
 174
 175         if (n < 1)
 176                 return -1;
 177
 178         while (n--) {
 179                 char file[256];
 180
 181                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 182                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 183                         sz = readlink(file, link, sizeof(link) - 1);
 184                         if (sz > 0) {
 185                                 char *orig;
 186
 187                                 link[sz] = '\0';
 188                                 orig = strstr(&file[1], "/");
 189                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 190                                         unlink(orig);
 191                         }
 192                 }
 193                 free(namelist[n]);
 194         }
 195         free(namelist);
 196
 197         return 0;
 198 }
 199
 200 int
 201 jffs2_switch(struct volume *v)
 202 {
 203         char *mp;
 204         int ret = -1;
 205
 206         if (find_overlay_mount("overlayfs:/tmp/root"))
 207                 return -1;
 208
 209         if (find_filesystem("overlay")) {
 210                 ULOG_ERR("overlayfs not supported by kernel\n");
 211                 return ret;
 212         }
 213
 214         mp = find_mount_point(v->blk, 0);
 215         if (mp) {
 216                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 217                 return -1;
 218         }
 219
 220         switch (volume_identify(v)) {
 221         case FS_NONE:
 222                 ULOG_ERR("no jffs2 marker found\n");
 223                 /* fall through */
 224
 225         case FS_DEADCODE:
 226                 ret = switch2jffs(v);
 227                 if (!ret) {
 228                         ULOG_INFO("performing overlay whiteout\n");
 229                         umount2("/tmp/root", MNT_DETACH);
 230                         foreachdir("/overlay/", handle_whiteout);
 231                 }
 232                 break;
 233
 234         case FS_JFFS2:
 235                 ret = overlay_mount(v, "jffs2");
 236                 if (ret)
 237                         break;
 238                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 239                         ULOG_ERR("switching to jffs2 failed\n");
 240                         ret = -1;
 241                 }
 242                 break;
 243
 244         case FS_UBIFS:
 245                 ret = overlay_mount(v, "ubifs");
 246                 if (ret)
 247                         break;
 248                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 249                         ULOG_ERR("switching to ubifs failed\n");
 250                         ret = -1;
 251                 }
 252                 break;
 253         }
 254
 255         if (ret)
 256                 return ret;
 257
 258         sync();
 259         fs_state_set("/overlay", FS_STATE_READY);
 260         return 0;
 261 }
 262
 263 static int overlay_mount_fs(struct volume *v)
 264 {
 265         char *fstype;
 266
 267         if (mkdir("/tmp/overlay", 0755)) {
 268                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 269                 return -1;
 270         }
 271
 272         fstype = "jffs2";
 273
 274         switch (volume_identify(v)) {
 275         case FS_UBIFS:
 276                 fstype = "ubifs";
 277                 break;
 278         }
 279
 280         volume_init(v);
 281
 282         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 283                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
 284                          fstype, v->blk, strerror(errno));
 285                 return -1;
 286         }
 287
 288         return -1;
 289 }
 290
 291 enum fs_state fs_state_get(const char *dir)
 292 {
 293         uint32_t val;
 294
 295         if (fs_getxattr(dir, "user.fs_state", &val, sizeof(val)) != sizeof(val))
 296                 return FS_STATE_UNKNOWN;
 297
 298         if (val > __FS_STATE_LAST)
 299                 return FS_STATE_UNKNOWN;
 300
 301         return val;
 302 }
 303
 304
 305 int fs_state_set(const char *dir, enum fs_state state)
 306 {
 307         uint32_t val = state;
 308
 309         return fs_setxattr(dir, "user.fs_state", &val, sizeof(val), 0);
 310 }
 311
 312
 313 int mount_overlay(struct volume *v)
 314 {
 315         char *mp;
 316
 317         if (!v)
 318                 return -1;
 319
 320         mp = find_mount_point(v->blk, 0);
 321         if (mp) {
 322                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 323                 return -1;
 324         }
 325
 326         overlay_mount_fs(v);
 327
 328         extroot_prefix = "/tmp/overlay";
 329         if (!mount_extroot()) {
 330                 ULOG_INFO("switched to extroot\n");
 331                 return 0;
 332         }
 333
 334         switch(fs_state_get("/tmp/overlay")) {
 335         case FS_STATE_UNKNOWN:
 336                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 337                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 338                         ULOG_ERR("unable to set filesystem state\n");
 339                         break;
 340                 }
 341         case FS_STATE_PENDING:
 342                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 343                 overlay_delete("/tmp/overlay", true);
 344                 break;
 345         case FS_STATE_READY:
 346                 break;
 347         }
 348
 349         ULOG_INFO("switching to jffs2 overlay\n");
 350         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 351                 ULOG_ERR("switching to jffs2 failed - fallback to ramoverlay\n");
 352                 return ramoverlay();
 353         }
 354
 355         return -1;
 356 }