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