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 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                         umode_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_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
 263 {
 264         struct posix_acl *acl;
 265         int rc;
 266
 267         cache_no_acl(inode);
 268
 269         if (S_ISLNK(*i_mode))
 270                 return 0;       /* Symlink always has no-ACL */
 271
 272         acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
 273         if (IS_ERR(acl))
 274                 return PTR_ERR(acl);
 275
 276         if (!acl) {
 277                 *i_mode &= ~current_umask();
 278         } else {
 279                 if (S_ISDIR(*i_mode))
 280                         set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
 281
 282                 rc = posix_acl_create(&acl, GFP_KERNEL, i_mode);
 283                 if (rc < 0)
 284                         return rc;
 285                 if (rc > 0)
 286                         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 287
 288                 posix_acl_release(acl);
 289         }
 290         return 0;
 291 }
 292
 293 int jffs2_init_acl_post(struct inode *inode)
 294 {
 295         int rc;
 296
 297         if (inode->i_default_acl) {
 298                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
 299                 if (rc)
 300                         return rc;
 301         }
 302
 303         if (inode->i_acl) {
 304                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
 305                 if (rc)
 306                         return rc;
 307         }
 308
 309         return 0;
 310 }
 311
 312 int jffs2_acl_chmod(struct inode *inode)
 313 {
 314         struct posix_acl *acl;
 315         int rc;
 316
 317         if (S_ISLNK(inode->i_mode))
 318                 return -EOPNOTSUPP;
 319         acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
 320         if (IS_ERR(acl) || !acl)
 321                 return PTR_ERR(acl);
 322         rc = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 323         if (rc)
 324                 return rc;
 325         rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, acl);
 326         posix_acl_release(acl);
 327         return rc;
 328 }
 329
 330 static size_t jffs2_acl_access_listxattr(struct dentry *dentry, char *list,
 331                 size_t list_size, const char *name, size_t name_len, int type)
 332 {
 333         const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
 334
 335         if (list && retlen <= list_size)
 336                 strcpy(list, POSIX_ACL_XATTR_ACCESS);
 337         return retlen;
 338 }
 339
 340 static size_t jffs2_acl_default_listxattr(struct dentry *dentry, char *list,
 341                 size_t list_size, const char *name, size_t name_len, int type)
 342 {
 343         const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
 344
 345         if (list && retlen <= list_size)
 346                 strcpy(list, POSIX_ACL_XATTR_DEFAULT);
 347         return retlen;
 348 }
 349
 350 static int jffs2_acl_getxattr(struct dentry *dentry, const char *name,
 351                 void *buffer, size_t size, int type)
 352 {
 353         struct posix_acl *acl;
 354         int rc;
 355
 356         if (name[0] != '\0')
 357                 return -EINVAL;
 358
 359         acl = jffs2_get_acl(dentry->d_inode, type);
 360         if (IS_ERR(acl))
 361                 return PTR_ERR(acl);
 362         if (!acl)
 363                 return -ENODATA;
 364         rc = posix_acl_to_xattr(acl, buffer, size);
 365         posix_acl_release(acl);
 366
 367         return rc;
 368 }
 369
 370 static int jffs2_acl_setxattr(struct dentry *dentry, const char *name,
 371                 const void *value, size_t size, int flags, int type)
 372 {
 373         struct posix_acl *acl;
 374         int rc;
 375
 376         if (name[0] != '\0')
 377                 return -EINVAL;
 378         if (!inode_owner_or_capable(dentry->d_inode))
 379                 return -EPERM;
 380
 381         if (value) {
 382                 acl = posix_acl_from_xattr(value, size);
 383                 if (IS_ERR(acl))
 384                         return PTR_ERR(acl);
 385                 if (acl) {
 386                         rc = posix_acl_valid(acl);
 387                         if (rc)
 388                                 goto out;
 389                 }
 390         } else {
 391                 acl = NULL;
 392         }
 393         rc = jffs2_set_acl(dentry->d_inode, type, acl);
 394  out:
 395         posix_acl_release(acl);
 396         return rc;
 397 }
 398
 399 const struct xattr_handler jffs2_acl_access_xattr_handler = {
 400         .prefix = POSIX_ACL_XATTR_ACCESS,
 401         .flags  = ACL_TYPE_DEFAULT,
 402         .list   = jffs2_acl_access_listxattr,
 403         .get    = jffs2_acl_getxattr,
 404         .set    = jffs2_acl_setxattr,
 405 };
 406
 407 const struct xattr_handler jffs2_acl_default_xattr_handler = {
 408         .prefix = POSIX_ACL_XATTR_DEFAULT,
 409         .flags  = ACL_TYPE_DEFAULT,
 410         .list   = jffs2_acl_default_listxattr,
 411         .get    = jffs2_acl_getxattr,
 412         .set    = jffs2_acl_setxattr,
 413 };