fs/overlayfs/overlayfs.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  *
   4  * Copyright (C) 2011 Novell Inc.
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/uuid.h>
   9 #include <linux/fs.h>
  10 #include "ovl_entry.h"
  11
  12 #undef pr_fmt
  13 #define pr_fmt(fmt) "overlayfs: " fmt
  14
  15 enum ovl_path_type {
  16         __OVL_PATH_UPPER        = (1 << 0),
  17         __OVL_PATH_MERGE        = (1 << 1),
  18         __OVL_PATH_ORIGIN       = (1 << 2),
  19 };
  20
  21 #define OVL_TYPE_UPPER(type)    ((type) & __OVL_PATH_UPPER)
  22 #define OVL_TYPE_MERGE(type)    ((type) & __OVL_PATH_MERGE)
  23 #define OVL_TYPE_ORIGIN(type)   ((type) & __OVL_PATH_ORIGIN)
  24
  25 #define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
  26 #define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
  27 #define OVL_XATTR_REDIRECT OVL_XATTR_PREFIX "redirect"
  28 #define OVL_XATTR_ORIGIN OVL_XATTR_PREFIX "origin"
  29 #define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
  30 #define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
  31 #define OVL_XATTR_UPPER OVL_XATTR_PREFIX "upper"
  32 #define OVL_XATTR_METACOPY OVL_XATTR_PREFIX "metacopy"
  33
  34 enum ovl_inode_flag {
  35         /* Pure upper dir that may contain non pure upper entries */
  36         OVL_IMPURE,
  37         /* Non-merge dir that may contain whiteout entries */
  38         OVL_WHITEOUTS,
  39         OVL_INDEX,
  40         OVL_UPPERDATA,
  41         /* Inode number will remain constant over copy up. */
  42         OVL_CONST_INO,
  43 };
  44
  45 enum ovl_entry_flag {
  46         OVL_E_UPPER_ALIAS,
  47         OVL_E_OPAQUE,
  48         OVL_E_CONNECTED,
  49 };
  50
  51 enum {
  52         OVL_XINO_OFF,
  53         OVL_XINO_AUTO,
  54         OVL_XINO_ON,
  55 };
  56
  57 /*
  58  * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
  59  * where:
  60  * origin.fh    - exported file handle of the lower file
  61  * origin.uuid  - uuid of the lower filesystem
  62  */
  63 #define OVL_FH_VERSION  0
  64 #define OVL_FH_MAGIC    0xfb
  65
  66 /* CPU byte order required for fid decoding:  */
  67 #define OVL_FH_FLAG_BIG_ENDIAN  (1 << 0)
  68 #define OVL_FH_FLAG_ANY_ENDIAN  (1 << 1)
  69 /* Is the real inode encoded in fid an upper inode? */
  70 #define OVL_FH_FLAG_PATH_UPPER  (1 << 2)
  71
  72 #define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN | \
  73                          OVL_FH_FLAG_PATH_UPPER)
  74
  75 #if defined(__LITTLE_ENDIAN)
  76 #define OVL_FH_FLAG_CPU_ENDIAN 0
  77 #elif defined(__BIG_ENDIAN)
  78 #define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
  79 #else
  80 #error Endianness not defined
  81 #endif
  82
  83 /* The type used to be returned by overlay exportfs for misaligned fid */
  84 #define OVL_FILEID_V0   0xfb
  85 /* The type returned by overlay exportfs for 32bit aligned fid */
  86 #define OVL_FILEID_V1   0xf8
  87
  88 /* On-disk format for "origin" file handle */
  89 struct ovl_fb {
  90         u8 version;     /* 0 */
  91         u8 magic;       /* 0xfb */
  92         u8 len;         /* size of this header + size of fid */
  93         u8 flags;       /* OVL_FH_FLAG_* */
  94         u8 type;        /* fid_type of fid */
  95         uuid_t uuid;    /* uuid of filesystem */
  96         u32 fid[];      /* file identifier should be 32bit aligned in-memory */
  97 } __packed;
  98
  99 /* In-memory and on-wire format for overlay file handle */
 100 struct ovl_fh {
 101         u8 padding[3];  /* make sure fb.fid is 32bit aligned */
 102         union {
 103                 struct ovl_fb fb;
 104                 u8 buf[0];
 105         };
 106 } __packed;
 107
 108 #define OVL_FH_WIRE_OFFSET      offsetof(struct ovl_fh, fb)
 109 #define OVL_FH_LEN(fh)          (OVL_FH_WIRE_OFFSET + (fh)->fb.len)
 110 #define OVL_FH_FID_OFFSET       (OVL_FH_WIRE_OFFSET + \
 111                                  offsetof(struct ovl_fb, fid))
 112
 113 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
 114 {
 115         int err = vfs_rmdir(dir, dentry);
 116
 117         pr_debug("rmdir(%pd2) = %i\n", dentry, err);
 118         return err;
 119 }
 120
 121 static inline int ovl_do_unlink(struct inode *dir, struct dentry *dentry)
 122 {
 123         int err = vfs_unlink(dir, dentry, NULL);
 124
 125         pr_debug("unlink(%pd2) = %i\n", dentry, err);
 126         return err;
 127 }
 128
 129 static inline int ovl_do_link(struct dentry *old_dentry, struct inode *dir,
 130                               struct dentry *new_dentry)
 131 {
 132         int err = vfs_link(old_dentry, dir, new_dentry, NULL);
 133
 134         pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
 135         return err;
 136 }
 137
 138 static inline int ovl_do_create(struct inode *dir, struct dentry *dentry,
 139                                 umode_t mode)
 140 {
 141         int err = vfs_create(dir, dentry, mode, true);
 142
 143         pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
 144         return err;
 145 }
 146
 147 static inline int ovl_do_mkdir(struct inode *dir, struct dentry *dentry,
 148                                umode_t mode)
 149 {
 150         int err = vfs_mkdir(dir, dentry, mode);
 151         pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
 152         return err;
 153 }
 154
 155 static inline int ovl_do_mknod(struct inode *dir, struct dentry *dentry,
 156                                umode_t mode, dev_t dev)
 157 {
 158         int err = vfs_mknod(dir, dentry, mode, dev);
 159
 160         pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
 161         return err;
 162 }
 163
 164 static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
 165                                  const char *oldname)
 166 {
 167         int err = vfs_symlink(dir, dentry, oldname);
 168
 169         pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
 170         return err;
 171 }
 172
 173 static inline int ovl_do_setxattr(struct dentry *dentry, const char *name,
 174                                   const void *value, size_t size, int flags)
 175 {
 176         int err = vfs_setxattr(dentry, name, value, size, flags);
 177         pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, 0x%x) = %i\n",
 178                  dentry, name, min((int)size, 48), value, size, flags, err);
 179         return err;
 180 }
 181
 182 static inline int ovl_do_removexattr(struct dentry *dentry, const char *name)
 183 {
 184         int err = vfs_removexattr(dentry, name);
 185         pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
 186         return err;
 187 }
 188
 189 static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
 190                                 struct inode *newdir, struct dentry *newdentry,
 191                                 unsigned int flags)
 192 {
 193         int err;
 194
 195         pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
 196         err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
 197         if (err) {
 198                 pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
 199                          olddentry, newdentry, err);
 200         }
 201         return err;
 202 }
 203
 204 static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
 205 {
 206         int err = vfs_whiteout(dir, dentry);
 207         pr_debug("whiteout(%pd2) = %i\n", dentry, err);
 208         return err;
 209 }
 210
 211 static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
 212 {
 213         struct dentry *ret = vfs_tmpfile(dentry, mode, 0);
 214         int err = PTR_ERR_OR_ZERO(ret);
 215
 216         pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
 217         return ret;
 218 }
 219
 220 static inline bool ovl_open_flags_need_copy_up(int flags)
 221 {
 222         if (!flags)
 223                 return false;
 224
 225         return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
 226 }
 227
 228 /* util.c */
 229 int ovl_want_write(struct dentry *dentry);
 230 void ovl_drop_write(struct dentry *dentry);
 231 struct dentry *ovl_workdir(struct dentry *dentry);
 232 const struct cred *ovl_override_creds(struct super_block *sb);
 233 int ovl_can_decode_fh(struct super_block *sb);
 234 struct dentry *ovl_indexdir(struct super_block *sb);
 235 bool ovl_index_all(struct super_block *sb);
 236 bool ovl_verify_lower(struct super_block *sb);
 237 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
 238 bool ovl_dentry_remote(struct dentry *dentry);
 239 void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
 240                              unsigned int mask);
 241 bool ovl_dentry_weird(struct dentry *dentry);
 242 enum ovl_path_type ovl_path_type(struct dentry *dentry);
 243 void ovl_path_upper(struct dentry *dentry, struct path *path);
 244 void ovl_path_lower(struct dentry *dentry, struct path *path);
 245 void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
 246 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
 247 struct dentry *ovl_dentry_upper(struct dentry *dentry);
 248 struct dentry *ovl_dentry_lower(struct dentry *dentry);
 249 struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
 250 const struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
 251 struct dentry *ovl_dentry_real(struct dentry *dentry);
 252 struct dentry *ovl_i_dentry_upper(struct inode *inode);
 253 struct inode *ovl_inode_upper(struct inode *inode);
 254 struct inode *ovl_inode_lower(struct inode *inode);
 255 struct inode *ovl_inode_lowerdata(struct inode *inode);
 256 struct inode *ovl_inode_real(struct inode *inode);
 257 struct inode *ovl_inode_realdata(struct inode *inode);
 258 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
 259 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
 260 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
 261 void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry);
 262 bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry);
 263 bool ovl_dentry_is_opaque(struct dentry *dentry);
 264 bool ovl_dentry_is_whiteout(struct dentry *dentry);
 265 void ovl_dentry_set_opaque(struct dentry *dentry);
 266 bool ovl_dentry_has_upper_alias(struct dentry *dentry);
 267 void ovl_dentry_set_upper_alias(struct dentry *dentry);
 268 bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags);
 269 bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags);
 270 bool ovl_has_upperdata(struct inode *inode);
 271 void ovl_set_upperdata(struct inode *inode);
 272 bool ovl_redirect_dir(struct super_block *sb);
 273 const char *ovl_dentry_get_redirect(struct dentry *dentry);
 274 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
 275 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
 276 void ovl_dir_modified(struct dentry *dentry, bool impurity);
 277 u64 ovl_dentry_version_get(struct dentry *dentry);
 278 bool ovl_is_whiteout(struct dentry *dentry);
 279 struct file *ovl_path_open(struct path *path, int flags);
 280 int ovl_copy_up_start(struct dentry *dentry, int flags);
 281 void ovl_copy_up_end(struct dentry *dentry);
 282 bool ovl_already_copied_up(struct dentry *dentry, int flags);
 283 bool ovl_check_origin_xattr(struct dentry *dentry);
 284 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
 285 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
 286                        const char *name, const void *value, size_t size,
 287                        int xerr);
 288 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
 289 void ovl_set_flag(unsigned long flag, struct inode *inode);
 290 void ovl_clear_flag(unsigned long flag, struct inode *inode);
 291 bool ovl_test_flag(unsigned long flag, struct inode *inode);
 292 bool ovl_inuse_trylock(struct dentry *dentry);
 293 void ovl_inuse_unlock(struct dentry *dentry);
 294 bool ovl_is_inuse(struct dentry *dentry);
 295 bool ovl_need_index(struct dentry *dentry);
 296 int ovl_nlink_start(struct dentry *dentry);
 297 void ovl_nlink_end(struct dentry *dentry);
 298 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
 299 int ovl_check_metacopy_xattr(struct dentry *dentry);
 300 bool ovl_is_metacopy_dentry(struct dentry *dentry);
 301 char *ovl_get_redirect_xattr(struct dentry *dentry, int padding);
 302 ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value,
 303                      size_t padding);
 304
 305 static inline bool ovl_is_impuredir(struct dentry *dentry)
 306 {
 307         return ovl_check_dir_xattr(dentry, OVL_XATTR_IMPURE);
 308 }
 309
 310 /*
 311  * With xino=auto, we do best effort to keep all inodes on same st_dev and
 312  * d_ino consistent with st_ino.
 313  * With xino=on, we do the same effort but we warn if we failed.
 314  */
 315 static inline bool ovl_xino_warn(struct super_block *sb)
 316 {
 317         return OVL_FS(sb)->config.xino == OVL_XINO_ON;
 318 }
 319
 320 /* All layers on same fs? */
 321 static inline bool ovl_same_fs(struct super_block *sb)
 322 {
 323         return OVL_FS(sb)->xino_mode == 0;
 324 }
 325
 326 /* All overlay inodes have same st_dev? */
 327 static inline bool ovl_same_dev(struct super_block *sb)
 328 {
 329         return OVL_FS(sb)->xino_mode >= 0;
 330 }
 331
 332 static inline unsigned int ovl_xino_bits(struct super_block *sb)
 333 {
 334         return ovl_same_dev(sb) ? OVL_FS(sb)->xino_mode : 0;
 335 }
 336
 337 static inline void ovl_inode_lock(struct inode *inode)
 338 {
 339         mutex_lock(&OVL_I(inode)->lock);
 340 }
 341
 342 static inline int ovl_inode_lock_interruptible(struct inode *inode)
 343 {
 344         return mutex_lock_interruptible(&OVL_I(inode)->lock);
 345 }
 346
 347 static inline void ovl_inode_unlock(struct inode *inode)
 348 {
 349         mutex_unlock(&OVL_I(inode)->lock);
 350 }
 351
 352
 353 /* namei.c */
 354 int ovl_check_fb_len(struct ovl_fb *fb, int fb_len);
 355
 356 static inline int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
 357 {
 358         if (fh_len < sizeof(struct ovl_fh))
 359                 return -EINVAL;
 360
 361         return ovl_check_fb_len(&fh->fb, fh_len - OVL_FH_WIRE_OFFSET);
 362 }
 363
 364 struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
 365                                   bool connected);
 366 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
 367                         struct dentry *upperdentry, struct ovl_path **stackp);
 368 int ovl_verify_set_fh(struct dentry *dentry, const char *name,
 369                       struct dentry *real, bool is_upper, bool set);
 370 struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index);
 371 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
 372 int ovl_get_index_name(struct dentry *origin, struct qstr *name);
 373 struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
 374 struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
 375                                 struct dentry *origin, bool verify);
 376 int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
 377 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 378                           unsigned int flags);
 379 bool ovl_lower_positive(struct dentry *dentry);
 380
 381 static inline int ovl_verify_origin(struct dentry *upper,
 382                                     struct dentry *origin, bool set)
 383 {
 384         return ovl_verify_set_fh(upper, OVL_XATTR_ORIGIN, origin, false, set);
 385 }
 386
 387 static inline int ovl_verify_upper(struct dentry *index,
 388                                     struct dentry *upper, bool set)
 389 {
 390         return ovl_verify_set_fh(index, OVL_XATTR_UPPER, upper, true, set);
 391 }
 392
 393 /* readdir.c */
 394 extern const struct file_operations ovl_dir_operations;
 395 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
 396 void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list);
 397 void ovl_cache_free(struct list_head *list);
 398 void ovl_dir_cache_free(struct inode *inode);
 399 int ovl_check_d_type_supported(struct path *realpath);
 400 int ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
 401                         struct dentry *dentry, int level);
 402 int ovl_indexdir_cleanup(struct ovl_fs *ofs);
 403
 404 /* inode.c */
 405 int ovl_set_nlink_upper(struct dentry *dentry);
 406 int ovl_set_nlink_lower(struct dentry *dentry);
 407 unsigned int ovl_get_nlink(struct dentry *lowerdentry,
 408                            struct dentry *upperdentry,
 409                            unsigned int fallback);
 410 int ovl_setattr(struct dentry *dentry, struct iattr *attr);
 411 int ovl_getattr(const struct path *path, struct kstat *stat,
 412                 u32 request_mask, unsigned int flags);
 413 int ovl_permission(struct inode *inode, int mask);
 414 int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
 415                   const void *value, size_t size, int flags);
 416 int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
 417                   void *value, size_t size);
 418 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
 419 struct posix_acl *ovl_get_acl(struct inode *inode, int type);
 420 int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags);
 421 bool ovl_is_private_xattr(const char *name);
 422
 423 struct ovl_inode_params {
 424         struct inode *newinode;
 425         struct dentry *upperdentry;
 426         struct ovl_path *lowerpath;
 427         bool index;
 428         unsigned int numlower;
 429         char *redirect;
 430         struct dentry *lowerdata;
 431 };
 432 void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
 433                     unsigned long ino, int fsid);
 434 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
 435 struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
 436                                bool is_upper);
 437 bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir);
 438 struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir);
 439 struct inode *ovl_get_inode(struct super_block *sb,
 440                             struct ovl_inode_params *oip);
 441 static inline void ovl_copyattr(struct inode *from, struct inode *to)
 442 {
 443         to->i_uid = from->i_uid;
 444         to->i_gid = from->i_gid;
 445         to->i_mode = from->i_mode;
 446         to->i_atime = from->i_atime;
 447         to->i_mtime = from->i_mtime;
 448         to->i_ctime = from->i_ctime;
 449         i_size_write(to, i_size_read(from));
 450 }
 451
 452 static inline void ovl_copyflags(struct inode *from, struct inode *to)
 453 {
 454         unsigned int mask = S_SYNC | S_IMMUTABLE | S_APPEND | S_NOATIME;
 455
 456         inode_set_flags(to, from->i_flags & mask, mask);
 457 }
 458
 459 /* dir.c */
 460 extern const struct inode_operations ovl_dir_inode_operations;
 461 int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir,
 462                              struct dentry *dentry);
 463 struct ovl_cattr {
 464         dev_t rdev;
 465         umode_t mode;
 466         const char *link;
 467         struct dentry *hardlink;
 468 };
 469
 470 #define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) })
 471
 472 struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
 473                                struct ovl_cattr *attr);
 474 int ovl_cleanup(struct inode *dir, struct dentry *dentry);
 475 struct dentry *ovl_lookup_temp(struct dentry *workdir);
 476 struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr);
 477
 478 /* file.c */
 479 extern const struct file_operations ovl_file_operations;
 480 int __init ovl_aio_request_cache_init(void);
 481 void ovl_aio_request_cache_destroy(void);
 482
 483 /* copy_up.c */
 484 int ovl_copy_up(struct dentry *dentry);
 485 int ovl_copy_up_with_data(struct dentry *dentry);
 486 int ovl_maybe_copy_up(struct dentry *dentry, int flags);
 487 int ovl_copy_xattr(struct dentry *old, struct dentry *new);
 488 int ovl_set_attr(struct dentry *upper, struct kstat *stat);
 489 struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper);
 490 int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
 491                    struct dentry *upper);
 492
 493 /* export.c */
 494 extern const struct export_operations ovl_export_operations;