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         system("cp -a /tmp/root/* /rom/overlay"); /**/
 147
 148         if (pivot("/rom", "/mnt")) {
 149                 ULOG_ERR("failed - pivot /rom /mnt: %s\n", strerror(errno));
 150                 return -1;
 151         }
 152
 153         if (mount_move("/mnt", "/tmp/root", "")) {
 154                 ULOG_ERR("failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
 155                 return -1;
 156         }
 157
 158         return fopivot("/overlay", "/rom");
 159 }
 160
 161 int
 162 handle_whiteout(const char *dir)
 163 {
 164         struct stat s;
 165         char link[256];
 166         ssize_t sz;
 167         struct dirent **namelist;
 168         int n;
 169
 170         n = scandir(dir, &namelist, NULL, NULL);
 171
 172         if (n < 1)
 173                 return -1;
 174
 175         while (n--) {
 176                 char file[256];
 177
 178                 snprintf(file, sizeof(file), "%s%s", dir, namelist[n]->d_name);
 179                 if (!lstat(file, &s) && S_ISLNK(s.st_mode)) {
 180                         sz = readlink(file, link, sizeof(link) - 1);
 181                         if (sz > 0) {
 182                                 char *orig;
 183
 184                                 link[sz] = '\0';
 185                                 orig = strstr(&file[1], "/");
 186                                 if (orig && !strcmp(link, "(overlay-whiteout)"))
 187                                         unlink(orig);
 188                         }
 189                 }
 190                 free(namelist[n]);
 191         }
 192         free(namelist);
 193
 194         return 0;
 195 }
 196
 197 int
 198 jffs2_switch(struct volume *v)
 199 {
 200         char *mp;
 201         int ret = -1;
 202
 203         if (find_overlay_mount("overlayfs:/tmp/root"))
 204                 return -1;
 205
 206         if (find_filesystem("overlay")) {
 207                 ULOG_ERR("overlayfs not supported by kernel\n");
 208                 return ret;
 209         }
 210
 211         mp = find_mount_point(v->blk, 0);
 212         if (mp) {
 213                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 214                 return -1;
 215         }
 216
 217         switch (volume_identify(v)) {
 218         case FS_NONE:
 219                 ULOG_ERR("no jffs2 marker found\n");
 220                 /* fall through */
 221
 222         case FS_DEADCODE:
 223                 ret = switch2jffs(v);
 224                 if (!ret) {
 225                         ULOG_INFO("performing overlay whiteout\n");
 226                         umount2("/tmp/root", MNT_DETACH);
 227                         foreachdir("/overlay/", handle_whiteout);
 228                 }
 229                 break;
 230
 231         case FS_JFFS2:
 232                 ret = overlay_mount(v, "jffs2");
 233                 if (ret)
 234                         break;
 235                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 236                         ULOG_ERR("switching to jffs2 failed\n");
 237                         ret = -1;
 238                 }
 239                 break;
 240
 241         case FS_UBIFS:
 242                 ret = overlay_mount(v, "ubifs");
 243                 if (ret)
 244                         break;
 245                 if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 246                         ULOG_ERR("switching to ubifs failed\n");
 247                         ret = -1;
 248                 }
 249                 break;
 250         }
 251
 252         if (ret)
 253                 return ret;
 254
 255         sync();
 256         fs_state_set("/overlay", FS_STATE_READY);
 257         return 0;
 258 }
 259
 260 static int overlay_mount_fs(struct volume *v)
 261 {
 262         char *fstype;
 263
 264         if (mkdir("/tmp/overlay", 0755)) {
 265                 ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
 266                 return -1;
 267         }
 268
 269         fstype = "jffs2";
 270
 271         switch (volume_identify(v)) {
 272         case FS_UBIFS:
 273                 fstype = "ubifs";
 274                 break;
 275         }
 276
 277         volume_init(v);
 278
 279         if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
 280                 ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
 281                          fstype, v->blk, strerror(errno));
 282                 return -1;
 283         }
 284
 285         return -1;
 286 }
 287
 288 enum fs_state fs_state_get(const char *dir)
 289 {
 290         uint32_t val;
 291
 292         if (fs_getxattr(dir, "user.fs_state", &val, sizeof(val)) != sizeof(val))
 293                 return FS_STATE_UNKNOWN;
 294
 295         if (val > __FS_STATE_LAST)
 296                 return FS_STATE_UNKNOWN;
 297
 298         return val;
 299 }
 300
 301
 302 int fs_state_set(const char *dir, enum fs_state state)
 303 {
 304         uint32_t val = state;
 305
 306         return fs_setxattr(dir, "user.fs_state", &val, sizeof(val), 0);
 307 }
 308
 309
 310 int mount_overlay(struct volume *v)
 311 {
 312         char *mp;
 313
 314         if (!v)
 315                 return -1;
 316
 317         mp = find_mount_point(v->blk, 0);
 318         if (mp) {
 319                 ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
 320                 return -1;
 321         }
 322
 323         overlay_mount_fs(v);
 324
 325         extroot_prefix = "/tmp/overlay";
 326         if (!mount_extroot()) {
 327                 ULOG_INFO("switched to extroot\n");
 328                 return 0;
 329         }
 330
 331         switch(fs_state_get("/tmp/overlay")) {
 332         case FS_STATE_UNKNOWN:
 333                 fs_state_set("/tmp/overlay", FS_STATE_PENDING);
 334                 if (fs_state_get("/tmp/overlay") != FS_STATE_PENDING) {
 335                         ULOG_ERR("unable to set filesystem state\n");
 336                         break;
 337                 }
 338         case FS_STATE_PENDING:
 339                 ULOG_INFO("overlay filesystem has not been fully initialized yet\n");
 340                 overlay_delete("/tmp/overlay", true);
 341                 break;
 342         case FS_STATE_READY:
 343                 break;
 344         }
 345
 346         ULOG_INFO("switching to jffs2 overlay\n");
 347         if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
 348                 ULOG_ERR("switching to jffs2 failed - fallback to ramoverlay\n");
 349                 return ramoverlay();
 350         }
 351
 352         return -1;
 353 }