Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 1 | /* |
| 2 | * |
| 3 | * Copyright (C) 2011 Novell Inc. |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 as published by |
| 7 | * the Free Software Foundation. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/fs.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <linux/file.h> |
| 13 | #include <linux/splice.h> |
| 14 | #include <linux/xattr.h> |
| 15 | #include <linux/security.h> |
| 16 | #include <linux/uaccess.h> |
| 17 | #include <linux/sched.h> |
| 18 | #include <linux/namei.h> |
| 19 | #include "overlayfs.h" |
| 20 | |
| 21 | #define OVL_COPY_UP_CHUNK_SIZE (1 << 20) |
| 22 | |
| 23 | int ovl_copy_xattr(struct dentry *old, struct dentry *new) |
| 24 | { |
Vito Caputo | e4ad29f | 2015-10-24 07:19:46 -0500 | [diff] [blame] | 25 | ssize_t list_size, size, value_size = 0; |
| 26 | char *buf, *name, *value = NULL; |
| 27 | int uninitialized_var(error); |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 28 | |
| 29 | if (!old->d_inode->i_op->getxattr || |
| 30 | !new->d_inode->i_op->getxattr) |
| 31 | return 0; |
| 32 | |
| 33 | list_size = vfs_listxattr(old, NULL, 0); |
| 34 | if (list_size <= 0) { |
| 35 | if (list_size == -EOPNOTSUPP) |
| 36 | return 0; |
| 37 | return list_size; |
| 38 | } |
| 39 | |
| 40 | buf = kzalloc(list_size, GFP_KERNEL); |
| 41 | if (!buf) |
| 42 | return -ENOMEM; |
| 43 | |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 44 | list_size = vfs_listxattr(old, buf, list_size); |
| 45 | if (list_size <= 0) { |
| 46 | error = list_size; |
Vito Caputo | e4ad29f | 2015-10-24 07:19:46 -0500 | [diff] [blame] | 47 | goto out; |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 48 | } |
| 49 | |
| 50 | for (name = buf; name < (buf + list_size); name += strlen(name) + 1) { |
Vito Caputo | e4ad29f | 2015-10-24 07:19:46 -0500 | [diff] [blame] | 51 | retry: |
| 52 | size = vfs_getxattr(old, name, value, value_size); |
| 53 | if (size == -ERANGE) |
| 54 | size = vfs_getxattr(old, name, NULL, 0); |
| 55 | |
Miklos Szeredi | 97daf8b | 2015-11-10 17:08:41 +0100 | [diff] [blame] | 56 | if (size < 0) { |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 57 | error = size; |
Vito Caputo | e4ad29f | 2015-10-24 07:19:46 -0500 | [diff] [blame] | 58 | break; |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 59 | } |
Vito Caputo | e4ad29f | 2015-10-24 07:19:46 -0500 | [diff] [blame] | 60 | |
| 61 | if (size > value_size) { |
| 62 | void *new; |
| 63 | |
| 64 | new = krealloc(value, size, GFP_KERNEL); |
| 65 | if (!new) { |
| 66 | error = -ENOMEM; |
| 67 | break; |
| 68 | } |
| 69 | value = new; |
| 70 | value_size = size; |
| 71 | goto retry; |
| 72 | } |
| 73 | |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 74 | error = vfs_setxattr(new, name, value, size, 0); |
| 75 | if (error) |
Vito Caputo | e4ad29f | 2015-10-24 07:19:46 -0500 | [diff] [blame] | 76 | break; |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 77 | } |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 78 | kfree(value); |
| 79 | out: |
| 80 | kfree(buf); |
| 81 | return error; |
| 82 | } |
| 83 | |
| 84 | static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len) |
| 85 | { |
| 86 | struct file *old_file; |
| 87 | struct file *new_file; |
| 88 | loff_t old_pos = 0; |
| 89 | loff_t new_pos = 0; |
| 90 | int error = 0; |
| 91 | |
| 92 | if (len == 0) |
| 93 | return 0; |
| 94 | |
David Howells | 0480334 | 2015-09-18 11:45:12 +0100 | [diff] [blame] | 95 | old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY); |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 96 | if (IS_ERR(old_file)) |
| 97 | return PTR_ERR(old_file); |
| 98 | |
David Howells | 0480334 | 2015-09-18 11:45:12 +0100 | [diff] [blame] | 99 | new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY); |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 100 | if (IS_ERR(new_file)) { |
| 101 | error = PTR_ERR(new_file); |
| 102 | goto out_fput; |
| 103 | } |
| 104 | |
| 105 | /* FIXME: copy up sparse files efficiently */ |
| 106 | while (len) { |
| 107 | size_t this_len = OVL_COPY_UP_CHUNK_SIZE; |
| 108 | long bytes; |
| 109 | |
| 110 | if (len < this_len) |
| 111 | this_len = len; |
| 112 | |
| 113 | if (signal_pending_state(TASK_KILLABLE, current)) { |
| 114 | error = -EINTR; |
| 115 | break; |
| 116 | } |
| 117 | |
| 118 | bytes = do_splice_direct(old_file, &old_pos, |
| 119 | new_file, &new_pos, |
| 120 | this_len, SPLICE_F_MOVE); |
| 121 | if (bytes <= 0) { |
| 122 | error = bytes; |
| 123 | break; |
| 124 | } |
| 125 | WARN_ON(old_pos != new_pos); |
| 126 | |
| 127 | len -= bytes; |
| 128 | } |
| 129 | |
| 130 | fput(new_file); |
| 131 | out_fput: |
| 132 | fput(old_file); |
| 133 | return error; |
| 134 | } |
| 135 | |
| 136 | static char *ovl_read_symlink(struct dentry *realdentry) |
| 137 | { |
| 138 | int res; |
| 139 | char *buf; |
| 140 | struct inode *inode = realdentry->d_inode; |
| 141 | mm_segment_t old_fs; |
| 142 | |
| 143 | res = -EINVAL; |
| 144 | if (!inode->i_op->readlink) |
| 145 | goto err; |
| 146 | |
| 147 | res = -ENOMEM; |
| 148 | buf = (char *) __get_free_page(GFP_KERNEL); |
| 149 | if (!buf) |
| 150 | goto err; |
| 151 | |
| 152 | old_fs = get_fs(); |
| 153 | set_fs(get_ds()); |
| 154 | /* The cast to a user pointer is valid due to the set_fs() */ |
| 155 | res = inode->i_op->readlink(realdentry, |
| 156 | (char __user *)buf, PAGE_SIZE - 1); |
| 157 | set_fs(old_fs); |
| 158 | if (res < 0) { |
| 159 | free_page((unsigned long) buf); |
| 160 | goto err; |
| 161 | } |
| 162 | buf[res] = '\0'; |
| 163 | |
| 164 | return buf; |
| 165 | |
| 166 | err: |
| 167 | return ERR_PTR(res); |
| 168 | } |
| 169 | |
| 170 | static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat) |
| 171 | { |
| 172 | struct iattr attr = { |
| 173 | .ia_valid = |
| 174 | ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET, |
| 175 | .ia_atime = stat->atime, |
| 176 | .ia_mtime = stat->mtime, |
| 177 | }; |
| 178 | |
| 179 | return notify_change(upperdentry, &attr, NULL); |
| 180 | } |
| 181 | |
| 182 | int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat) |
| 183 | { |
| 184 | int err = 0; |
| 185 | |
| 186 | if (!S_ISLNK(stat->mode)) { |
| 187 | struct iattr attr = { |
| 188 | .ia_valid = ATTR_MODE, |
| 189 | .ia_mode = stat->mode, |
| 190 | }; |
| 191 | err = notify_change(upperdentry, &attr, NULL); |
| 192 | } |
| 193 | if (!err) { |
| 194 | struct iattr attr = { |
| 195 | .ia_valid = ATTR_UID | ATTR_GID, |
| 196 | .ia_uid = stat->uid, |
| 197 | .ia_gid = stat->gid, |
| 198 | }; |
| 199 | err = notify_change(upperdentry, &attr, NULL); |
| 200 | } |
| 201 | if (!err) |
| 202 | ovl_set_timestamps(upperdentry, stat); |
| 203 | |
| 204 | return err; |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 205 | } |
| 206 | |
| 207 | static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir, |
| 208 | struct dentry *dentry, struct path *lowerpath, |
Al Viro | 0f7ff2d | 2015-12-06 12:31:07 -0500 | [diff] [blame] | 209 | struct kstat *stat, const char *link) |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 210 | { |
| 211 | struct inode *wdir = workdir->d_inode; |
| 212 | struct inode *udir = upperdir->d_inode; |
| 213 | struct dentry *newdentry = NULL; |
| 214 | struct dentry *upper = NULL; |
| 215 | umode_t mode = stat->mode; |
| 216 | int err; |
| 217 | |
| 218 | newdentry = ovl_lookup_temp(workdir, dentry); |
| 219 | err = PTR_ERR(newdentry); |
| 220 | if (IS_ERR(newdentry)) |
| 221 | goto out; |
| 222 | |
| 223 | upper = lookup_one_len(dentry->d_name.name, upperdir, |
| 224 | dentry->d_name.len); |
| 225 | err = PTR_ERR(upper); |
| 226 | if (IS_ERR(upper)) |
| 227 | goto out1; |
| 228 | |
| 229 | /* Can't properly set mode on creation because of the umask */ |
| 230 | stat->mode &= S_IFMT; |
| 231 | err = ovl_create_real(wdir, newdentry, stat, link, NULL, true); |
| 232 | stat->mode = mode; |
| 233 | if (err) |
| 234 | goto out2; |
| 235 | |
| 236 | if (S_ISREG(stat->mode)) { |
| 237 | struct path upperpath; |
| 238 | ovl_path_upper(dentry, &upperpath); |
| 239 | BUG_ON(upperpath.dentry != NULL); |
| 240 | upperpath.dentry = newdentry; |
| 241 | |
| 242 | err = ovl_copy_up_data(lowerpath, &upperpath, stat->size); |
| 243 | if (err) |
| 244 | goto out_cleanup; |
| 245 | } |
| 246 | |
| 247 | err = ovl_copy_xattr(lowerpath->dentry, newdentry); |
| 248 | if (err) |
| 249 | goto out_cleanup; |
| 250 | |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame^] | 251 | inode_lock(newdentry->d_inode); |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 252 | err = ovl_set_attr(newdentry, stat); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame^] | 253 | inode_unlock(newdentry->d_inode); |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 254 | if (err) |
| 255 | goto out_cleanup; |
| 256 | |
| 257 | err = ovl_do_rename(wdir, newdentry, udir, upper, 0); |
| 258 | if (err) |
| 259 | goto out_cleanup; |
| 260 | |
| 261 | ovl_dentry_update(dentry, newdentry); |
| 262 | newdentry = NULL; |
| 263 | |
| 264 | /* |
| 265 | * Non-directores become opaque when copied up. |
| 266 | */ |
| 267 | if (!S_ISDIR(stat->mode)) |
| 268 | ovl_dentry_set_opaque(dentry, true); |
| 269 | out2: |
| 270 | dput(upper); |
| 271 | out1: |
| 272 | dput(newdentry); |
| 273 | out: |
| 274 | return err; |
| 275 | |
| 276 | out_cleanup: |
| 277 | ovl_cleanup(wdir, newdentry); |
David Howells | ab79efa | 2015-09-18 11:45:22 +0100 | [diff] [blame] | 278 | goto out2; |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 279 | } |
| 280 | |
| 281 | /* |
| 282 | * Copy up a single dentry |
| 283 | * |
| 284 | * Directory renames only allowed on "pure upper" (already created on |
| 285 | * upper filesystem, never copied up). Directories which are on lower or |
| 286 | * are merged may not be renamed. For these -EXDEV is returned and |
| 287 | * userspace has to deal with it. This means, when copying up a |
| 288 | * directory we can rely on it and ancestors being stable. |
| 289 | * |
| 290 | * Non-directory renames start with copy up of source if necessary. The |
| 291 | * actual rename will only proceed once the copy up was successful. Copy |
| 292 | * up uses upper parent i_mutex for exclusion. Since rename can change |
| 293 | * d_parent it is possible that the copy up will lock the old parent. At |
| 294 | * that point the file will have already been copied up anyway. |
| 295 | */ |
| 296 | int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, |
Al Viro | 0f7ff2d | 2015-12-06 12:31:07 -0500 | [diff] [blame] | 297 | struct path *lowerpath, struct kstat *stat) |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 298 | { |
| 299 | struct dentry *workdir = ovl_workdir(dentry); |
| 300 | int err; |
| 301 | struct kstat pstat; |
| 302 | struct path parentpath; |
| 303 | struct dentry *upperdir; |
| 304 | struct dentry *upperdentry; |
| 305 | const struct cred *old_cred; |
| 306 | struct cred *override_cred; |
| 307 | char *link = NULL; |
| 308 | |
Miklos Szeredi | cc6f67b | 2015-05-19 14:30:12 +0200 | [diff] [blame] | 309 | if (WARN_ON(!workdir)) |
| 310 | return -EROFS; |
| 311 | |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 312 | ovl_path_upper(parent, &parentpath); |
| 313 | upperdir = parentpath.dentry; |
| 314 | |
| 315 | err = vfs_getattr(&parentpath, &pstat); |
| 316 | if (err) |
| 317 | return err; |
| 318 | |
| 319 | if (S_ISLNK(stat->mode)) { |
| 320 | link = ovl_read_symlink(lowerpath->dentry); |
| 321 | if (IS_ERR(link)) |
| 322 | return PTR_ERR(link); |
| 323 | } |
| 324 | |
| 325 | err = -ENOMEM; |
| 326 | override_cred = prepare_creds(); |
| 327 | if (!override_cred) |
| 328 | goto out_free_link; |
| 329 | |
| 330 | override_cred->fsuid = stat->uid; |
| 331 | override_cred->fsgid = stat->gid; |
| 332 | /* |
| 333 | * CAP_SYS_ADMIN for copying up extended attributes |
| 334 | * CAP_DAC_OVERRIDE for create |
| 335 | * CAP_FOWNER for chmod, timestamp update |
| 336 | * CAP_FSETID for chmod |
| 337 | * CAP_CHOWN for chown |
| 338 | * CAP_MKNOD for mknod |
| 339 | */ |
| 340 | cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); |
| 341 | cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); |
| 342 | cap_raise(override_cred->cap_effective, CAP_FOWNER); |
| 343 | cap_raise(override_cred->cap_effective, CAP_FSETID); |
| 344 | cap_raise(override_cred->cap_effective, CAP_CHOWN); |
| 345 | cap_raise(override_cred->cap_effective, CAP_MKNOD); |
| 346 | old_cred = override_creds(override_cred); |
| 347 | |
| 348 | err = -EIO; |
| 349 | if (lock_rename(workdir, upperdir) != NULL) { |
| 350 | pr_err("overlayfs: failed to lock workdir+upperdir\n"); |
| 351 | goto out_unlock; |
| 352 | } |
| 353 | upperdentry = ovl_dentry_upper(dentry); |
| 354 | if (upperdentry) { |
Al Viro | 0f7ff2d | 2015-12-06 12:31:07 -0500 | [diff] [blame] | 355 | /* Raced with another copy-up? Nothing to do, then... */ |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 356 | err = 0; |
Al Viro | 0f7ff2d | 2015-12-06 12:31:07 -0500 | [diff] [blame] | 357 | goto out_unlock; |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 358 | } |
| 359 | |
| 360 | err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath, |
Al Viro | 0f7ff2d | 2015-12-06 12:31:07 -0500 | [diff] [blame] | 361 | stat, link); |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 362 | if (!err) { |
| 363 | /* Restore timestamps on parent (best effort) */ |
| 364 | ovl_set_timestamps(upperdir, &pstat); |
| 365 | } |
| 366 | out_unlock: |
| 367 | unlock_rename(workdir, upperdir); |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 368 | revert_creds(old_cred); |
| 369 | put_cred(override_cred); |
| 370 | |
| 371 | out_free_link: |
| 372 | if (link) |
| 373 | free_page((unsigned long) link); |
| 374 | |
| 375 | return err; |
| 376 | } |
| 377 | |
| 378 | int ovl_copy_up(struct dentry *dentry) |
| 379 | { |
| 380 | int err; |
| 381 | |
| 382 | err = 0; |
| 383 | while (!err) { |
| 384 | struct dentry *next; |
| 385 | struct dentry *parent; |
| 386 | struct path lowerpath; |
| 387 | struct kstat stat; |
| 388 | enum ovl_path_type type = ovl_path_type(dentry); |
| 389 | |
Miklos Szeredi | 1afaba1 | 2014-12-13 00:59:42 +0100 | [diff] [blame] | 390 | if (OVL_TYPE_UPPER(type)) |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 391 | break; |
| 392 | |
| 393 | next = dget(dentry); |
| 394 | /* find the topmost dentry not yet copied up */ |
| 395 | for (;;) { |
| 396 | parent = dget_parent(next); |
| 397 | |
| 398 | type = ovl_path_type(parent); |
Miklos Szeredi | 1afaba1 | 2014-12-13 00:59:42 +0100 | [diff] [blame] | 399 | if (OVL_TYPE_UPPER(type)) |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 400 | break; |
| 401 | |
| 402 | dput(next); |
| 403 | next = parent; |
| 404 | } |
| 405 | |
| 406 | ovl_path_lower(next, &lowerpath); |
| 407 | err = vfs_getattr(&lowerpath, &stat); |
| 408 | if (!err) |
Al Viro | 0f7ff2d | 2015-12-06 12:31:07 -0500 | [diff] [blame] | 409 | err = ovl_copy_up_one(parent, next, &lowerpath, &stat); |
Miklos Szeredi | e9be9d5 | 2014-10-24 00:14:38 +0200 | [diff] [blame] | 410 | |
| 411 | dput(parent); |
| 412 | dput(next); |
| 413 | } |
| 414 | |
| 415 | return err; |
| 416 | } |