fs/jffs2/acl.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright © 2006  NEC Corporation
   5  *
   6  * Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
   7  *
   8  * For licensing information, see the file 'LICENCE' in this directory.
   9  *
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/fs.h>
  15 #include <linux/sched.h>
  16 #include <linux/time.h>
  17 #include <linux/crc32.h>
  18 #include <linux/jffs2.h>
  19 #include <linux/xattr.h>
  20 #include <linux/posix_acl_xattr.h>
  21 #include <linux/mtd/mtd.h>
  22 #include "nodelist.h"
  23
  24 static size_t jffs2_acl_size(int count)
  25 {
  26         if (count <= 4) {
  27                 return sizeof(struct jffs2_acl_header)
  28                        + count * sizeof(struct jffs2_acl_entry_short);
  29         } else {
  30                 return sizeof(struct jffs2_acl_header)
  31                        + 4 * sizeof(struct jffs2_acl_entry_short)
  32                        + (count - 4) * sizeof(struct jffs2_acl_entry);
  33         }
  34 }
  35
  36 static int jffs2_acl_count(size_t size)
  37 {
  38         size_t s;
  39
  40         size -= sizeof(struct jffs2_acl_header);
  41         if (size < 4 * sizeof(struct jffs2_acl_entry_short)) {
  42                 if (size % sizeof(struct jffs2_acl_entry_short))
  43                         return -1;
  44                 return size / sizeof(struct jffs2_acl_entry_short);
  45         } else {
  46                 s = size - 4 * sizeof(struct jffs2_acl_entry_short);
  47                 if (s % sizeof(struct jffs2_acl_entry))
  48                         return -1;
  49                 return s / sizeof(struct jffs2_acl_entry) + 4;
  50         }
  51 }
  52
  53 static struct posix_acl *jffs2_acl_from_medium(void *value, size_t size)
  54 {
  55         void *end = value + size;
  56         struct jffs2_acl_header *header = value;
  57         struct jffs2_acl_entry *entry;
  58         struct posix_acl *acl;
  59         uint32_t ver;
  60         int i, count;
  61
  62         if (!value)
  63                 return NULL;
  64         if (size < sizeof(struct jffs2_acl_header))
  65                 return ERR_PTR(-EINVAL);
  66         ver = je32_to_cpu(header->a_version);
  67         if (ver != JFFS2_ACL_VERSION) {
  68                 JFFS2_WARNING("Invalid ACL version. (=%u)\n", ver);
  69                 return ERR_PTR(-EINVAL);
  70         }
  71
  72         value += sizeof(struct jffs2_acl_header);
  73         count = jffs2_acl_count(size);
  74         if (count < 0)
  75                 return ERR_PTR(-EINVAL);
  76         if (count == 0)
  77                 return NULL;
  78
  79         acl = posix_acl_alloc(count, GFP_KERNEL);
  80         if (!acl)
  81                 return ERR_PTR(-ENOMEM);
  82
  83         for (i=0; i < count; i++) {
  84                 entry = value;
  85                 if (value + sizeof(struct jffs2_acl_entry_short) > end)
  86                         goto fail;
  87                 acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
  88                 acl->a_entries[i].e_perm = je16_to_cpu(entry->e_perm);
  89                 switch (acl->a_entries[i].e_tag) {
  90                         case ACL_USER_OBJ:
  91                         case ACL_GROUP_OBJ:
  92                         case ACL_MASK:
  93                         case ACL_OTHER:
  94                                 value += sizeof(struct jffs2_acl_entry_short);
  95                                 acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
  96                                 break;
  97
  98                         case ACL_USER:
  99                         case ACL_GROUP:
 100                                 value += sizeof(struct jffs2_acl_entry);
 101                                 if (value > end)
 102                                         goto fail;
 103                                 acl->a_entries[i].e_id = je32_to_cpu(entry->e_id);
 104                                 break;
 105
 106                         default:
 107                                 goto fail;
 108                 }
 109         }
 110         if (value != end)
 111                 goto fail;
 112         return acl;
 113  fail:
 114         posix_acl_release(acl);
 115         return ERR_PTR(-EINVAL);
 116 }
 117
 118 static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
 119 {
 120         struct jffs2_acl_header *header;
 121         struct jffs2_acl_entry *entry;
 122         void *e;
 123         size_t i;
 124
 125         *size = jffs2_acl_size(acl->a_count);
 126         header = kmalloc(sizeof(*header) + acl->a_count * sizeof(*entry), GFP_KERNEL);
 127         if (!header)
 128                 return ERR_PTR(-ENOMEM);
 129         header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
 130         e = header + 1;
 131         for (i=0; i < acl->a_count; i++) {
 132                 entry = e;
 133                 entry->e_tag = cpu_to_je16(acl->a_entries[i].e_tag);
 134                 entry->e_perm = cpu_to_je16(acl->a_entries[i].e_perm);
 135                 switch(acl->a_entries[i].e_tag) {
 136                         case ACL_USER:
 137                         case ACL_GROUP:
 138                                 entry->e_id = cpu_to_je32(acl->a_entries[i].e_id);
 139                                 e += sizeof(struct jffs2_acl_entry);
 140                                 break;
 141
 142                         case ACL_USER_OBJ:
 143                         case ACL_GROUP_OBJ:
 144                         case ACL_MASK:
 145                         case ACL_OTHER:
 146                                 e += sizeof(struct jffs2_acl_entry_short);
 147                                 break;
 148
 149                         default:
 150                                 goto fail;
 151                 }
 152         }
 153         return header;
 154  fail:
 155         kfree(header);
 156         return ERR_PTR(-EINVAL);
 157 }
 158
 159 static struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
 160 {
 161         struct posix_acl *acl;
 162         char *value = NULL;
 163         int rc, xprefix;
 164
 165         acl = get_cached_acl(inode, type);
 166         if (acl != ACL_NOT_CACHED)
 167                 return acl;
 168
 169         switch (type) {
 170         case ACL_TYPE_ACCESS:
 171                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
 172                 break;
 173         case ACL_TYPE_DEFAULT:
 174                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
 175                 break;
 176         default:
 177                 BUG();
 178         }
 179         rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
 180         if (rc > 0) {
 181                 value = kmalloc(rc, GFP_KERNEL);
 182                 if (!value)
 183                         return ERR_PTR(-ENOMEM);
 184                 rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
 185         }
 186         if (rc > 0) {
 187                 acl = jffs2_acl_from_medium(value, rc);
 188         } else if (rc == -ENODATA || rc == -ENOSYS) {
 189                 acl = NULL;
 190         } else {
 191                 acl = ERR_PTR(rc);
 192         }
 193         if (value)
 194                 kfree(value);
 195         if (!IS_ERR(acl))
 196                 set_cached_acl(inode, type, acl);
 197         return acl;
 198 }
 199
 200 static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
 201 {
 202         char *value = NULL;
 203         size_t size = 0;
 204         int rc;
 205
 206         if (acl) {
 207                 value = jffs2_acl_to_medium(acl, &size);
 208                 if (IS_ERR(value))
 209                         return PTR_ERR(value);
 210         }
 211         rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
 212         if (!value && rc == -ENODATA)
 213                 rc = 0;
 214         kfree(value);
 215
 216         return rc;
 217 }
 218
 219 static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 220 {
 221         int rc, xprefix;
 222
 223         if (S_ISLNK(inode->i_mode))
 224                 return -EOPNOTSUPP;
 225
 226         switch (type) {
 227         case ACL_TYPE_ACCESS:
 228                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
 229                 if (acl) {
 230                         mode_t mode = inode->i_mode;
 231                         rc = posix_acl_equiv_mode(acl, &mode);
 232                         if (rc < 0)
 233                                 return rc;
 234                         if (inode->i_mode != mode) {
 235                                 struct iattr attr;
 236
 237                                 attr.ia_valid = ATTR_MODE | ATTR_CTIME;
 238                                 attr.ia_mode = mode;
 239                                 attr.ia_ctime = CURRENT_TIME_SEC;
 240                                 rc = jffs2_do_setattr(inode, &attr);
 241                                 if (rc < 0)
 242                                         return rc;
 243                         }
 244                         if (rc == 0)
 245                                 acl = NULL;
 246                 }
 247                 break;
 248         case ACL_TYPE_DEFAULT:
 249                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
 250                 if (!S_ISDIR(inode->i_mode))
 251                         return acl ? -EACCES : 0;
 252                 break;
 253         default:
 254                 return -EINVAL;
 255         }
 256         rc = __jffs2_set_acl(inode, xprefix, acl);
 257         if (!rc)
 258                 set_cached_acl(inode, type, acl);
 259         return rc;
 260 }
 261
 262 int jffs2_check_acl(struct inode *inode, int mask, unsigned int flags)
 263 {
 264         struct posix_acl *acl;
 265         int rc;
 266
 267         if (flags & IPERM_FLAG_RCU)
 268                 return -ECHILD;
 269
 270         acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
 271         if (IS_ERR(acl))
 272                 return PTR_ERR(acl);
 273         if (acl) {
 274                 rc = posix_acl_permission(inode, acl, mask);
 275                 posix_acl_release(acl);
 276                 return rc;
 277         }
 278         return -EAGAIN;
 279 }
 280
 281 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, int *i_mode)
 282 {
 283         struct posix_acl *acl, *clone;
 284         int rc;
 285
 286         cache_no_acl(inode);
 287
 288         if (S_ISLNK(*i_mode))
 289                 return 0;       /* Symlink always has no-ACL */
 290
 291         acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
 292         if (IS_ERR(acl))
 293                 return PTR_ERR(acl);
 294
 295         if (!acl) {
 296                 *i_mode &= ~current_umask();
 297         } else {
 298                 if (S_ISDIR(*i_mode))
 299                         set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
 300
 301                 clone = posix_acl_clone(acl, GFP_KERNEL);
 302                 if (!clone)
 303                         return -ENOMEM;
 304                 rc = posix_acl_create_masq(clone, (mode_t *)i_mode);
 305                 if (rc < 0) {
 306                         posix_acl_release(clone);
 307                         return rc;
 308                 }
 309                 if (rc > 0)
 310                         set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
 311
 312                 posix_acl_release(clone);
 313         }
 314         return 0;
 315 }
 316
 317 int jffs2_init_acl_post(struct inode *inode)
 318 {
 319         int rc;
 320
 321         if (inode->i_default_acl) {
 322                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
 323                 if (rc)
 324                         return rc;
 325         }
 326
 327         if (inode->i_acl) {
 328                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
 329                 if (rc)
 330                         return rc;
 331         }
 332
 333         return 0;
 334 }
 335
 336 int jffs2_acl_chmod(struct inode *inode)
 337 {
 338         struct posix_acl *acl, *clone;
 339         int rc;
 340
 341         if (S_ISLNK(inode->i_mode))
 342                 return -EOPNOTSUPP;
 343         acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
 344         if (IS_ERR(acl) || !acl)
 345                 return PTR_ERR(acl);
 346         clone = posix_acl_clone(acl, GFP_KERNEL);
 347         posix_acl_release(acl);
 348         if (!clone)
 349                 return -ENOMEM;
 350         rc = posix_acl_chmod_masq(clone, inode->i_mode);
 351         if (!rc)
 352                 rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
 353         posix_acl_release(clone);
 354         return rc;
 355 }
 356
 357 static size_t jffs2_acl_access_listxattr(struct dentry *dentry, char *list,
 358                 size_t list_size, const char *name, size_t name_len, int type)
 359 {
 360         const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
 361
 362         if (list && retlen <= list_size)
 363                 strcpy(list, POSIX_ACL_XATTR_ACCESS);
 364         return retlen;
 365 }
 366
 367 static size_t jffs2_acl_default_listxattr(struct dentry *dentry, char *list,
 368                 size_t list_size, const char *name, size_t name_len, int type)
 369 {
 370         const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
 371
 372         if (list && retlen <= list_size)
 373                 strcpy(list, POSIX_ACL_XATTR_DEFAULT);
 374         return retlen;
 375 }
 376
 377 static int jffs2_acl_getxattr(struct dentry *dentry, const char *name,
 378                 void *buffer, size_t size, int type)
 379 {
 380         struct posix_acl *acl;
 381         int rc;
 382
 383         if (name[0] != '\0')
 384                 return -EINVAL;
 385
 386         acl = jffs2_get_acl(dentry->d_inode, type);
 387         if (IS_ERR(acl))
 388                 return PTR_ERR(acl);
 389         if (!acl)
 390                 return -ENODATA;
 391         rc = posix_acl_to_xattr(acl, buffer, size);
 392         posix_acl_release(acl);
 393
 394         return rc;
 395 }
 396
 397 static int jffs2_acl_setxattr(struct dentry *dentry, const char *name,
 398                 const void *value, size_t size, int flags, int type)
 399 {
 400         struct posix_acl *acl;
 401         int rc;
 402
 403         if (name[0] != '\0')
 404                 return -EINVAL;
 405         if (!is_owner_or_cap(dentry->d_inode))
 406                 return -EPERM;
 407
 408         if (value) {
 409                 acl = posix_acl_from_xattr(value, size);
 410                 if (IS_ERR(acl))
 411                         return PTR_ERR(acl);
 412                 if (acl) {
 413                         rc = posix_acl_valid(acl);
 414                         if (rc)
 415                                 goto out;
 416                 }
 417         } else {
 418                 acl = NULL;
 419         }
 420         rc = jffs2_set_acl(dentry->d_inode, type, acl);
 421  out:
 422         posix_acl_release(acl);
 423         return rc;
 424 }
 425
 426 const struct xattr_handler jffs2_acl_access_xattr_handler = {
 427         .prefix = POSIX_ACL_XATTR_ACCESS,
 428         .flags  = ACL_TYPE_DEFAULT,
 429         .list   = jffs2_acl_access_listxattr,
 430         .get    = jffs2_acl_getxattr,
 431         .set    = jffs2_acl_setxattr,
 432 };
 433
 434 const struct xattr_handler jffs2_acl_default_xattr_handler = {
 435         .prefix = POSIX_ACL_XATTR_DEFAULT,
 436         .flags  = ACL_TYPE_DEFAULT,
 437         .list   = jffs2_acl_default_listxattr,
 438         .get    = jffs2_acl_getxattr,
 439         .set    = jffs2_acl_setxattr,
 440 };