| 1 | /* |
| 2 | * Copyright (c) 2008, Christoph Hellwig |
| 3 | * All Rights Reserved. |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU General Public License as |
| 7 | * published by the Free Software Foundation. |
| 8 | * |
| 9 | * This program is distributed in the hope that it would be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write the Free Software Foundation, |
| 16 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 17 | */ |
| 18 | #include "xfs.h" |
| 19 | #include "xfs_acl.h" |
| 20 | #include "xfs_attr.h" |
| 21 | #include "xfs_bmap_btree.h" |
| 22 | #include "xfs_inode.h" |
| 23 | #include "xfs_vnodeops.h" |
| 24 | #include "xfs_trace.h" |
| 25 | #include <linux/slab.h> |
| 26 | #include <linux/xattr.h> |
| 27 | #include <linux/posix_acl_xattr.h> |
| 28 | |
| 29 | |
| 30 | /* |
| 31 | * Locking scheme: |
| 32 | * - all ACL updates are protected by inode->i_mutex, which is taken before |
| 33 | * calling into this file. |
| 34 | */ |
| 35 | |
| 36 | STATIC struct posix_acl * |
| 37 | xfs_acl_from_disk(struct xfs_acl *aclp) |
| 38 | { |
| 39 | struct posix_acl_entry *acl_e; |
| 40 | struct posix_acl *acl; |
| 41 | struct xfs_acl_entry *ace; |
| 42 | int count, i; |
| 43 | |
| 44 | count = be32_to_cpu(aclp->acl_cnt); |
| 45 | |
| 46 | acl = posix_acl_alloc(count, GFP_KERNEL); |
| 47 | if (!acl) |
| 48 | return ERR_PTR(-ENOMEM); |
| 49 | |
| 50 | for (i = 0; i < count; i++) { |
| 51 | acl_e = &acl->a_entries[i]; |
| 52 | ace = &aclp->acl_entry[i]; |
| 53 | |
| 54 | /* |
| 55 | * The tag is 32 bits on disk and 16 bits in core. |
| 56 | * |
| 57 | * Because every access to it goes through the core |
| 58 | * format first this is not a problem. |
| 59 | */ |
| 60 | acl_e->e_tag = be32_to_cpu(ace->ae_tag); |
| 61 | acl_e->e_perm = be16_to_cpu(ace->ae_perm); |
| 62 | |
| 63 | switch (acl_e->e_tag) { |
| 64 | case ACL_USER: |
| 65 | case ACL_GROUP: |
| 66 | acl_e->e_id = be32_to_cpu(ace->ae_id); |
| 67 | break; |
| 68 | case ACL_USER_OBJ: |
| 69 | case ACL_GROUP_OBJ: |
| 70 | case ACL_MASK: |
| 71 | case ACL_OTHER: |
| 72 | acl_e->e_id = ACL_UNDEFINED_ID; |
| 73 | break; |
| 74 | default: |
| 75 | goto fail; |
| 76 | } |
| 77 | } |
| 78 | return acl; |
| 79 | |
| 80 | fail: |
| 81 | posix_acl_release(acl); |
| 82 | return ERR_PTR(-EINVAL); |
| 83 | } |
| 84 | |
| 85 | STATIC void |
| 86 | xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl) |
| 87 | { |
| 88 | const struct posix_acl_entry *acl_e; |
| 89 | struct xfs_acl_entry *ace; |
| 90 | int i; |
| 91 | |
| 92 | aclp->acl_cnt = cpu_to_be32(acl->a_count); |
| 93 | for (i = 0; i < acl->a_count; i++) { |
| 94 | ace = &aclp->acl_entry[i]; |
| 95 | acl_e = &acl->a_entries[i]; |
| 96 | |
| 97 | ace->ae_tag = cpu_to_be32(acl_e->e_tag); |
| 98 | ace->ae_id = cpu_to_be32(acl_e->e_id); |
| 99 | ace->ae_perm = cpu_to_be16(acl_e->e_perm); |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | struct posix_acl * |
| 104 | xfs_get_acl(struct inode *inode, int type) |
| 105 | { |
| 106 | struct xfs_inode *ip = XFS_I(inode); |
| 107 | struct posix_acl *acl; |
| 108 | struct xfs_acl *xfs_acl; |
| 109 | int len = sizeof(struct xfs_acl); |
| 110 | unsigned char *ea_name; |
| 111 | int error; |
| 112 | |
| 113 | acl = get_cached_acl(inode, type); |
| 114 | if (acl != ACL_NOT_CACHED) |
| 115 | return acl; |
| 116 | |
| 117 | switch (type) { |
| 118 | case ACL_TYPE_ACCESS: |
| 119 | ea_name = SGI_ACL_FILE; |
| 120 | break; |
| 121 | case ACL_TYPE_DEFAULT: |
| 122 | ea_name = SGI_ACL_DEFAULT; |
| 123 | break; |
| 124 | default: |
| 125 | BUG(); |
| 126 | } |
| 127 | |
| 128 | /* |
| 129 | * If we have a cached ACLs value just return it, not need to |
| 130 | * go out to the disk. |
| 131 | */ |
| 132 | |
| 133 | xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL); |
| 134 | if (!xfs_acl) |
| 135 | return ERR_PTR(-ENOMEM); |
| 136 | |
| 137 | error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl, |
| 138 | &len, ATTR_ROOT); |
| 139 | if (error) { |
| 140 | /* |
| 141 | * If the attribute doesn't exist make sure we have a negative |
| 142 | * cache entry, for any other error assume it is transient and |
| 143 | * leave the cache entry as ACL_NOT_CACHED. |
| 144 | */ |
| 145 | if (error == -ENOATTR) { |
| 146 | acl = NULL; |
| 147 | goto out_update_cache; |
| 148 | } |
| 149 | goto out; |
| 150 | } |
| 151 | |
| 152 | acl = xfs_acl_from_disk(xfs_acl); |
| 153 | if (IS_ERR(acl)) |
| 154 | goto out; |
| 155 | |
| 156 | out_update_cache: |
| 157 | set_cached_acl(inode, type, acl); |
| 158 | out: |
| 159 | kfree(xfs_acl); |
| 160 | return acl; |
| 161 | } |
| 162 | |
| 163 | STATIC int |
| 164 | xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl) |
| 165 | { |
| 166 | struct xfs_inode *ip = XFS_I(inode); |
| 167 | unsigned char *ea_name; |
| 168 | int error; |
| 169 | |
| 170 | if (S_ISLNK(inode->i_mode)) |
| 171 | return -EOPNOTSUPP; |
| 172 | |
| 173 | switch (type) { |
| 174 | case ACL_TYPE_ACCESS: |
| 175 | ea_name = SGI_ACL_FILE; |
| 176 | break; |
| 177 | case ACL_TYPE_DEFAULT: |
| 178 | if (!S_ISDIR(inode->i_mode)) |
| 179 | return acl ? -EACCES : 0; |
| 180 | ea_name = SGI_ACL_DEFAULT; |
| 181 | break; |
| 182 | default: |
| 183 | return -EINVAL; |
| 184 | } |
| 185 | |
| 186 | if (acl) { |
| 187 | struct xfs_acl *xfs_acl; |
| 188 | int len; |
| 189 | |
| 190 | xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL); |
| 191 | if (!xfs_acl) |
| 192 | return -ENOMEM; |
| 193 | |
| 194 | xfs_acl_to_disk(xfs_acl, acl); |
| 195 | len = sizeof(struct xfs_acl) - |
| 196 | (sizeof(struct xfs_acl_entry) * |
| 197 | (XFS_ACL_MAX_ENTRIES - acl->a_count)); |
| 198 | |
| 199 | error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl, |
| 200 | len, ATTR_ROOT); |
| 201 | |
| 202 | kfree(xfs_acl); |
| 203 | } else { |
| 204 | /* |
| 205 | * A NULL ACL argument means we want to remove the ACL. |
| 206 | */ |
| 207 | error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT); |
| 208 | |
| 209 | /* |
| 210 | * If the attribute didn't exist to start with that's fine. |
| 211 | */ |
| 212 | if (error == -ENOATTR) |
| 213 | error = 0; |
| 214 | } |
| 215 | |
| 216 | if (!error) |
| 217 | set_cached_acl(inode, type, acl); |
| 218 | return error; |
| 219 | } |
| 220 | |
| 221 | int |
| 222 | xfs_check_acl(struct inode *inode, int mask, unsigned int flags) |
| 223 | { |
| 224 | struct xfs_inode *ip; |
| 225 | struct posix_acl *acl; |
| 226 | int error = -EAGAIN; |
| 227 | |
| 228 | if (flags & IPERM_FLAG_RCU) |
| 229 | return -ECHILD; |
| 230 | |
| 231 | ip = XFS_I(inode); |
| 232 | trace_xfs_check_acl(ip); |
| 233 | |
| 234 | /* |
| 235 | * If there is no attribute fork no ACL exists on this inode and |
| 236 | * we can skip the whole exercise. |
| 237 | */ |
| 238 | if (!XFS_IFORK_Q(ip)) |
| 239 | return -EAGAIN; |
| 240 | |
| 241 | acl = xfs_get_acl(inode, ACL_TYPE_ACCESS); |
| 242 | if (IS_ERR(acl)) |
| 243 | return PTR_ERR(acl); |
| 244 | if (acl) { |
| 245 | error = posix_acl_permission(inode, acl, mask); |
| 246 | posix_acl_release(acl); |
| 247 | } |
| 248 | |
| 249 | return error; |
| 250 | } |
| 251 | |
| 252 | static int |
| 253 | xfs_set_mode(struct inode *inode, mode_t mode) |
| 254 | { |
| 255 | int error = 0; |
| 256 | |
| 257 | if (mode != inode->i_mode) { |
| 258 | struct iattr iattr; |
| 259 | |
| 260 | iattr.ia_valid = ATTR_MODE | ATTR_CTIME; |
| 261 | iattr.ia_mode = mode; |
| 262 | iattr.ia_ctime = current_fs_time(inode->i_sb); |
| 263 | |
| 264 | error = -xfs_setattr(XFS_I(inode), &iattr, XFS_ATTR_NOACL); |
| 265 | } |
| 266 | |
| 267 | return error; |
| 268 | } |
| 269 | |
| 270 | static int |
| 271 | xfs_acl_exists(struct inode *inode, unsigned char *name) |
| 272 | { |
| 273 | int len = sizeof(struct xfs_acl); |
| 274 | |
| 275 | return (xfs_attr_get(XFS_I(inode), name, NULL, &len, |
| 276 | ATTR_ROOT|ATTR_KERNOVAL) == 0); |
| 277 | } |
| 278 | |
| 279 | int |
| 280 | posix_acl_access_exists(struct inode *inode) |
| 281 | { |
| 282 | return xfs_acl_exists(inode, SGI_ACL_FILE); |
| 283 | } |
| 284 | |
| 285 | int |
| 286 | posix_acl_default_exists(struct inode *inode) |
| 287 | { |
| 288 | if (!S_ISDIR(inode->i_mode)) |
| 289 | return 0; |
| 290 | return xfs_acl_exists(inode, SGI_ACL_DEFAULT); |
| 291 | } |
| 292 | |
| 293 | /* |
| 294 | * No need for i_mutex because the inode is not yet exposed to the VFS. |
| 295 | */ |
| 296 | int |
| 297 | xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl) |
| 298 | { |
| 299 | struct posix_acl *clone; |
| 300 | mode_t mode; |
| 301 | int error = 0, inherit = 0; |
| 302 | |
| 303 | if (S_ISDIR(inode->i_mode)) { |
| 304 | error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl); |
| 305 | if (error) |
| 306 | return error; |
| 307 | } |
| 308 | |
| 309 | clone = posix_acl_clone(default_acl, GFP_KERNEL); |
| 310 | if (!clone) |
| 311 | return -ENOMEM; |
| 312 | |
| 313 | mode = inode->i_mode; |
| 314 | error = posix_acl_create_masq(clone, &mode); |
| 315 | if (error < 0) |
| 316 | goto out_release_clone; |
| 317 | |
| 318 | /* |
| 319 | * If posix_acl_create_masq returns a positive value we need to |
| 320 | * inherit a permission that can't be represented using the Unix |
| 321 | * mode bits and we actually need to set an ACL. |
| 322 | */ |
| 323 | if (error > 0) |
| 324 | inherit = 1; |
| 325 | |
| 326 | error = xfs_set_mode(inode, mode); |
| 327 | if (error) |
| 328 | goto out_release_clone; |
| 329 | |
| 330 | if (inherit) |
| 331 | error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone); |
| 332 | |
| 333 | out_release_clone: |
| 334 | posix_acl_release(clone); |
| 335 | return error; |
| 336 | } |
| 337 | |
| 338 | int |
| 339 | xfs_acl_chmod(struct inode *inode) |
| 340 | { |
| 341 | struct posix_acl *acl, *clone; |
| 342 | int error; |
| 343 | |
| 344 | if (S_ISLNK(inode->i_mode)) |
| 345 | return -EOPNOTSUPP; |
| 346 | |
| 347 | acl = xfs_get_acl(inode, ACL_TYPE_ACCESS); |
| 348 | if (IS_ERR(acl) || !acl) |
| 349 | return PTR_ERR(acl); |
| 350 | |
| 351 | clone = posix_acl_clone(acl, GFP_KERNEL); |
| 352 | posix_acl_release(acl); |
| 353 | if (!clone) |
| 354 | return -ENOMEM; |
| 355 | |
| 356 | error = posix_acl_chmod_masq(clone, inode->i_mode); |
| 357 | if (!error) |
| 358 | error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone); |
| 359 | |
| 360 | posix_acl_release(clone); |
| 361 | return error; |
| 362 | } |
| 363 | |
| 364 | static int |
| 365 | xfs_xattr_acl_get(struct dentry *dentry, const char *name, |
| 366 | void *value, size_t size, int type) |
| 367 | { |
| 368 | struct posix_acl *acl; |
| 369 | int error; |
| 370 | |
| 371 | acl = xfs_get_acl(dentry->d_inode, type); |
| 372 | if (IS_ERR(acl)) |
| 373 | return PTR_ERR(acl); |
| 374 | if (acl == NULL) |
| 375 | return -ENODATA; |
| 376 | |
| 377 | error = posix_acl_to_xattr(acl, value, size); |
| 378 | posix_acl_release(acl); |
| 379 | |
| 380 | return error; |
| 381 | } |
| 382 | |
| 383 | static int |
| 384 | xfs_xattr_acl_set(struct dentry *dentry, const char *name, |
| 385 | const void *value, size_t size, int flags, int type) |
| 386 | { |
| 387 | struct inode *inode = dentry->d_inode; |
| 388 | struct posix_acl *acl = NULL; |
| 389 | int error = 0; |
| 390 | |
| 391 | if (flags & XATTR_CREATE) |
| 392 | return -EINVAL; |
| 393 | if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) |
| 394 | return value ? -EACCES : 0; |
| 395 | if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER)) |
| 396 | return -EPERM; |
| 397 | |
| 398 | if (!value) |
| 399 | goto set_acl; |
| 400 | |
| 401 | acl = posix_acl_from_xattr(value, size); |
| 402 | if (!acl) { |
| 403 | /* |
| 404 | * acl_set_file(3) may request that we set default ACLs with |
| 405 | * zero length -- defend (gracefully) against that here. |
| 406 | */ |
| 407 | goto out; |
| 408 | } |
| 409 | if (IS_ERR(acl)) { |
| 410 | error = PTR_ERR(acl); |
| 411 | goto out; |
| 412 | } |
| 413 | |
| 414 | error = posix_acl_valid(acl); |
| 415 | if (error) |
| 416 | goto out_release; |
| 417 | |
| 418 | error = -EINVAL; |
| 419 | if (acl->a_count > XFS_ACL_MAX_ENTRIES) |
| 420 | goto out_release; |
| 421 | |
| 422 | if (type == ACL_TYPE_ACCESS) { |
| 423 | mode_t mode = inode->i_mode; |
| 424 | error = posix_acl_equiv_mode(acl, &mode); |
| 425 | |
| 426 | if (error <= 0) { |
| 427 | posix_acl_release(acl); |
| 428 | acl = NULL; |
| 429 | |
| 430 | if (error < 0) |
| 431 | return error; |
| 432 | } |
| 433 | |
| 434 | error = xfs_set_mode(inode, mode); |
| 435 | if (error) |
| 436 | goto out_release; |
| 437 | } |
| 438 | |
| 439 | set_acl: |
| 440 | error = xfs_set_acl(inode, type, acl); |
| 441 | out_release: |
| 442 | posix_acl_release(acl); |
| 443 | out: |
| 444 | return error; |
| 445 | } |
| 446 | |
| 447 | const struct xattr_handler xfs_xattr_acl_access_handler = { |
| 448 | .prefix = POSIX_ACL_XATTR_ACCESS, |
| 449 | .flags = ACL_TYPE_ACCESS, |
| 450 | .get = xfs_xattr_acl_get, |
| 451 | .set = xfs_xattr_acl_set, |
| 452 | }; |
| 453 | |
| 454 | const struct xattr_handler xfs_xattr_acl_default_handler = { |
| 455 | .prefix = POSIX_ACL_XATTR_DEFAULT, |
| 456 | .flags = ACL_TYPE_DEFAULT, |
| 457 | .get = xfs_xattr_acl_get, |
| 458 | .set = xfs_xattr_acl_set, |
| 459 | }; |