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 unsigned int count, i; 43 44 count = be32_to_cpu(aclp->acl_cnt); 45 if (count > XFS_ACL_MAX_ENTRIES) 46 return ERR_PTR(-EFSCORRUPTED); 47 48 acl = posix_acl_alloc(count, GFP_KERNEL); 49 if (!acl) 50 return ERR_PTR(-ENOMEM); 51 52 for (i = 0; i < count; i++) { 53 acl_e = &acl->a_entries[i]; 54 ace = &aclp->acl_entry[i]; 55 56 /* 57 * The tag is 32 bits on disk and 16 bits in core. 58 * 59 * Because every access to it goes through the core 60 * format first this is not a problem. 61 */ 62 acl_e->e_tag = be32_to_cpu(ace->ae_tag); 63 acl_e->e_perm = be16_to_cpu(ace->ae_perm); 64 65 switch (acl_e->e_tag) { 66 case ACL_USER: 67 case ACL_GROUP: 68 acl_e->e_id = be32_to_cpu(ace->ae_id); 69 break; 70 case ACL_USER_OBJ: 71 case ACL_GROUP_OBJ: 72 case ACL_MASK: 73 case ACL_OTHER: 74 acl_e->e_id = ACL_UNDEFINED_ID; 75 break; 76 default: 77 goto fail; 78 } 79 } 80 return acl; 81 82 fail: 83 posix_acl_release(acl); 84 return ERR_PTR(-EINVAL); 85 } 86 87 STATIC void 88 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl) 89 { 90 const struct posix_acl_entry *acl_e; 91 struct xfs_acl_entry *ace; 92 int i; 93 94 aclp->acl_cnt = cpu_to_be32(acl->a_count); 95 for (i = 0; i < acl->a_count; i++) { 96 ace = &aclp->acl_entry[i]; 97 acl_e = &acl->a_entries[i]; 98 99 ace->ae_tag = cpu_to_be32(acl_e->e_tag); 100 ace->ae_id = cpu_to_be32(acl_e->e_id); 101 ace->ae_perm = cpu_to_be16(acl_e->e_perm); 102 } 103 } 104 105 struct posix_acl * 106 xfs_get_acl(struct inode *inode, int type) 107 { 108 struct xfs_inode *ip = XFS_I(inode); 109 struct posix_acl *acl; 110 struct xfs_acl *xfs_acl; 111 int len = sizeof(struct xfs_acl); 112 unsigned char *ea_name; 113 int error; 114 115 acl = get_cached_acl(inode, type); 116 if (acl != ACL_NOT_CACHED) 117 return acl; 118 119 trace_xfs_get_acl(ip); 120 121 switch (type) { 122 case ACL_TYPE_ACCESS: 123 ea_name = SGI_ACL_FILE; 124 break; 125 case ACL_TYPE_DEFAULT: 126 ea_name = SGI_ACL_DEFAULT; 127 break; 128 default: 129 BUG(); 130 } 131 132 /* 133 * If we have a cached ACLs value just return it, not need to 134 * go out to the disk. 135 */ 136 137 xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL); 138 if (!xfs_acl) 139 return ERR_PTR(-ENOMEM); 140 141 error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl, 142 &len, ATTR_ROOT); 143 if (error) { 144 /* 145 * If the attribute doesn't exist make sure we have a negative 146 * cache entry, for any other error assume it is transient and 147 * leave the cache entry as ACL_NOT_CACHED. 148 */ 149 if (error == -ENOATTR) { 150 acl = NULL; 151 goto out_update_cache; 152 } 153 goto out; 154 } 155 156 acl = xfs_acl_from_disk(xfs_acl); 157 if (IS_ERR(acl)) 158 goto out; 159 160 out_update_cache: 161 set_cached_acl(inode, type, acl); 162 out: 163 kfree(xfs_acl); 164 return acl; 165 } 166 167 STATIC int 168 xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl) 169 { 170 struct xfs_inode *ip = XFS_I(inode); 171 unsigned char *ea_name; 172 int error; 173 174 if (S_ISLNK(inode->i_mode)) 175 return -EOPNOTSUPP; 176 177 switch (type) { 178 case ACL_TYPE_ACCESS: 179 ea_name = SGI_ACL_FILE; 180 break; 181 case ACL_TYPE_DEFAULT: 182 if (!S_ISDIR(inode->i_mode)) 183 return acl ? -EACCES : 0; 184 ea_name = SGI_ACL_DEFAULT; 185 break; 186 default: 187 return -EINVAL; 188 } 189 190 if (acl) { 191 struct xfs_acl *xfs_acl; 192 int len; 193 194 xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL); 195 if (!xfs_acl) 196 return -ENOMEM; 197 198 xfs_acl_to_disk(xfs_acl, acl); 199 len = sizeof(struct xfs_acl) - 200 (sizeof(struct xfs_acl_entry) * 201 (XFS_ACL_MAX_ENTRIES - acl->a_count)); 202 203 error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl, 204 len, ATTR_ROOT); 205 206 kfree(xfs_acl); 207 } else { 208 /* 209 * A NULL ACL argument means we want to remove the ACL. 210 */ 211 error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT); 212 213 /* 214 * If the attribute didn't exist to start with that's fine. 215 */ 216 if (error == -ENOATTR) 217 error = 0; 218 } 219 220 if (!error) 221 set_cached_acl(inode, type, acl); 222 return error; 223 } 224 225 static int 226 xfs_set_mode(struct inode *inode, umode_t mode) 227 { 228 int error = 0; 229 230 if (mode != inode->i_mode) { 231 struct iattr iattr; 232 233 iattr.ia_valid = ATTR_MODE | ATTR_CTIME; 234 iattr.ia_mode = mode; 235 iattr.ia_ctime = current_fs_time(inode->i_sb); 236 237 error = -xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL); 238 } 239 240 return error; 241 } 242 243 static int 244 xfs_acl_exists(struct inode *inode, unsigned char *name) 245 { 246 int len = sizeof(struct xfs_acl); 247 248 return (xfs_attr_get(XFS_I(inode), name, NULL, &len, 249 ATTR_ROOT|ATTR_KERNOVAL) == 0); 250 } 251 252 int 253 posix_acl_access_exists(struct inode *inode) 254 { 255 return xfs_acl_exists(inode, SGI_ACL_FILE); 256 } 257 258 int 259 posix_acl_default_exists(struct inode *inode) 260 { 261 if (!S_ISDIR(inode->i_mode)) 262 return 0; 263 return xfs_acl_exists(inode, SGI_ACL_DEFAULT); 264 } 265 266 /* 267 * No need for i_mutex because the inode is not yet exposed to the VFS. 268 */ 269 int 270 xfs_inherit_acl(struct inode *inode, struct posix_acl *acl) 271 { 272 umode_t mode = inode->i_mode; 273 int error = 0, inherit = 0; 274 275 if (S_ISDIR(inode->i_mode)) { 276 error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, acl); 277 if (error) 278 goto out; 279 } 280 281 error = posix_acl_create(&acl, GFP_KERNEL, &mode); 282 if (error < 0) 283 return error; 284 285 /* 286 * If posix_acl_create returns a positive value we need to 287 * inherit a permission that can't be represented using the Unix 288 * mode bits and we actually need to set an ACL. 289 */ 290 if (error > 0) 291 inherit = 1; 292 293 error = xfs_set_mode(inode, mode); 294 if (error) 295 goto out; 296 297 if (inherit) 298 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl); 299 300 out: 301 posix_acl_release(acl); 302 return error; 303 } 304 305 int 306 xfs_acl_chmod(struct inode *inode) 307 { 308 struct posix_acl *acl; 309 int error; 310 311 if (S_ISLNK(inode->i_mode)) 312 return -EOPNOTSUPP; 313 314 acl = xfs_get_acl(inode, ACL_TYPE_ACCESS); 315 if (IS_ERR(acl) || !acl) 316 return PTR_ERR(acl); 317 318 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode); 319 if (error) 320 return error; 321 322 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl); 323 posix_acl_release(acl); 324 return error; 325 } 326 327 static int 328 xfs_xattr_acl_get(struct dentry *dentry, const char *name, 329 void *value, size_t size, int type) 330 { 331 struct posix_acl *acl; 332 int error; 333 334 acl = xfs_get_acl(dentry->d_inode, type); 335 if (IS_ERR(acl)) 336 return PTR_ERR(acl); 337 if (acl == NULL) 338 return -ENODATA; 339 340 error = posix_acl_to_xattr(acl, value, size); 341 posix_acl_release(acl); 342 343 return error; 344 } 345 346 static int 347 xfs_xattr_acl_set(struct dentry *dentry, const char *name, 348 const void *value, size_t size, int flags, int type) 349 { 350 struct inode *inode = dentry->d_inode; 351 struct posix_acl *acl = NULL; 352 int error = 0; 353 354 if (flags & XATTR_CREATE) 355 return -EINVAL; 356 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) 357 return value ? -EACCES : 0; 358 if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER)) 359 return -EPERM; 360 361 if (!value) 362 goto set_acl; 363 364 acl = posix_acl_from_xattr(value, size); 365 if (!acl) { 366 /* 367 * acl_set_file(3) may request that we set default ACLs with 368 * zero length -- defend (gracefully) against that here. 369 */ 370 goto out; 371 } 372 if (IS_ERR(acl)) { 373 error = PTR_ERR(acl); 374 goto out; 375 } 376 377 error = posix_acl_valid(acl); 378 if (error) 379 goto out_release; 380 381 error = -EINVAL; 382 if (acl->a_count > XFS_ACL_MAX_ENTRIES) 383 goto out_release; 384 385 if (type == ACL_TYPE_ACCESS) { 386 umode_t mode = inode->i_mode; 387 error = posix_acl_equiv_mode(acl, &mode); 388 389 if (error <= 0) { 390 posix_acl_release(acl); 391 acl = NULL; 392 393 if (error < 0) 394 return error; 395 } 396 397 error = xfs_set_mode(inode, mode); 398 if (error) 399 goto out_release; 400 } 401 402 set_acl: 403 error = xfs_set_acl(inode, type, acl); 404 out_release: 405 posix_acl_release(acl); 406 out: 407 return error; 408 } 409 410 const struct xattr_handler xfs_xattr_acl_access_handler = { 411 .prefix = POSIX_ACL_XATTR_ACCESS, 412 .flags = ACL_TYPE_ACCESS, 413 .get = xfs_xattr_acl_get, 414 .set = xfs_xattr_acl_set, 415 }; 416 417 const struct xattr_handler xfs_xattr_acl_default_handler = { 418 .prefix = POSIX_ACL_XATTR_DEFAULT, 419 .flags = ACL_TYPE_DEFAULT, 420 .get = xfs_xattr_acl_get, 421 .set = xfs_xattr_acl_set, 422 }; 423