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                                 acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
  98                                 break;
  99
 100                         case ACL_USER:
 101                         case ACL_GROUP:
 102                                 value += sizeof(struct jffs2_acl_entry);
 103                                 if (value > end)
 104                                         goto fail;
 105                                 acl->a_entries[i].e_id = je32_to_cpu(entry->e_id);
 106                                 break;
 107
 108                         default:
 109                                 goto fail;
 110                 }
 111         }
 112         if (value != end)
 113                 goto fail;
 114         return acl;
 115  fail:
 116         posix_acl_release(acl);
 117         return ERR_PTR(-EINVAL);
 118 }
 119
 120 static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
 121 {
 122         struct jffs2_acl_header *header;
 123         struct jffs2_acl_entry *entry;
 124         void *e;
 125         size_t i;
 126
 127         *size = jffs2_acl_size(acl->a_count);
 128         header = kmalloc(sizeof(*header) + acl->a_count * sizeof(*entry), GFP_KERNEL);
 129         if (!header)
 130                 return ERR_PTR(-ENOMEM);
 131         header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
 132         e = header + 1;
 133         for (i=0; i < acl->a_count; i++) {
 134                 entry = e;
 135                 entry->e_tag = cpu_to_je16(acl->a_entries[i].e_tag);
 136                 entry->e_perm = cpu_to_je16(acl->a_entries[i].e_perm);
 137                 switch(acl->a_entries[i].e_tag) {
 138                         case ACL_USER:
 139                         case ACL_GROUP:
 140                                 entry->e_id = cpu_to_je32(acl->a_entries[i].e_id);
 141                                 e += sizeof(struct jffs2_acl_entry);
 142                                 break;
 143
 144                         case ACL_USER_OBJ:
 145                         case ACL_GROUP_OBJ:
 146                         case ACL_MASK:
 147                         case ACL_OTHER:
 148                                 e += sizeof(struct jffs2_acl_entry_short);
 149                                 break;
 150
 151                         default:
 152                                 goto fail;
 153                 }
 154         }
 155         return header;
 156  fail:
 157         kfree(header);
 158         return ERR_PTR(-EINVAL);
 159 }
 160
 161 struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
 162 {
 163         struct posix_acl *acl;
 164         char *value = NULL;
 165         int rc, xprefix;
 166
 167         acl = get_cached_acl(inode, type);
 168         if (acl != ACL_NOT_CACHED)
 169                 return acl;
 170
 171         switch (type) {
 172         case ACL_TYPE_ACCESS:
 173                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
 174                 break;
 175         case ACL_TYPE_DEFAULT:
 176                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
 177                 break;
 178         default:
 179                 BUG();
 180         }
 181         rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
 182         if (rc > 0) {
 183                 value = kmalloc(rc, GFP_KERNEL);
 184                 if (!value)
 185                         return ERR_PTR(-ENOMEM);
 186                 rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
 187         }
 188         if (rc > 0) {
 189                 acl = jffs2_acl_from_medium(value, rc);
 190         } else if (rc == -ENODATA || rc == -ENOSYS) {
 191                 acl = NULL;
 192         } else {
 193                 acl = ERR_PTR(rc);
 194         }
 195         if (value)
 196                 kfree(value);
 197         if (!IS_ERR(acl))
 198                 set_cached_acl(inode, type, acl);
 199         return acl;
 200 }
 201
 202 static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
 203 {
 204         char *value = NULL;
 205         size_t size = 0;
 206         int rc;
 207
 208         if (acl) {
 209                 value = jffs2_acl_to_medium(acl, &size);
 210                 if (IS_ERR(value))
 211                         return PTR_ERR(value);
 212         }
 213         rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
 214         if (!value && rc == -ENODATA)
 215                 rc = 0;
 216         kfree(value);
 217
 218         return rc;
 219 }
 220
 221 static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 222 {
 223         int rc, xprefix;
 224
 225         if (S_ISLNK(inode->i_mode))
 226                 return -EOPNOTSUPP;
 227
 228         switch (type) {
 229         case ACL_TYPE_ACCESS:
 230                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
 231                 if (acl) {
 232                         umode_t mode = inode->i_mode;
 233                         rc = posix_acl_equiv_mode(acl, &mode);
 234                         if (rc < 0)
 235                                 return rc;
 236                         if (inode->i_mode != mode) {
 237                                 struct iattr attr;
 238
 239                                 attr.ia_valid = ATTR_MODE | ATTR_CTIME;
 240                                 attr.ia_mode = mode;
 241                                 attr.ia_ctime = CURRENT_TIME_SEC;
 242                                 rc = jffs2_do_setattr(inode, &attr);
 243                                 if (rc < 0)
 244                                         return rc;
 245                         }
 246                         if (rc == 0)
 247                                 acl = NULL;
 248                 }
 249                 break;
 250         case ACL_TYPE_DEFAULT:
 251                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
 252                 if (!S_ISDIR(inode->i_mode))
 253                         return acl ? -EACCES : 0;
 254                 break;
 255         default:
 256                 return -EINVAL;
 257         }
 258         rc = __jffs2_set_acl(inode, xprefix, acl);
 259         if (!rc)
 260                 set_cached_acl(inode, type, acl);
 261         return rc;
 262 }
 263
 264 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
 265 {
 266         struct posix_acl *acl;
 267         int rc;
 268
 269         cache_no_acl(inode);
 270
 271         if (S_ISLNK(*i_mode))
 272                 return 0;       /* Symlink always has no-ACL */
 273
 274         acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
 275         if (IS_ERR(acl))
 276                 return PTR_ERR(acl);
 277
 278         if (!acl) {
 279                 *i_mode &= ~current_umask();
 280         } else {
 281                 if (S_ISDIR(*i_mode))
 282                         set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
 283
 284                 rc = posix_acl_create(&acl, GFP_KERNEL, i_mode);
 285                 if (rc < 0)
 286                         return rc;
 287                 if (rc > 0)
 288                         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 289
 290                 posix_acl_release(acl);
 291         }
 292         return 0;
 293 }
 294
 295 int jffs2_init_acl_post(struct inode *inode)
 296 {
 297         int rc;
 298
 299         if (inode->i_default_acl) {
 300                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
 301                 if (rc)
 302                         return rc;
 303         }
 304
 305         if (inode->i_acl) {
 306                 rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
 307                 if (rc)
 308                         return rc;
 309         }
 310
 311         return 0;
 312 }
 313
 314 int jffs2_acl_chmod(struct inode *inode)
 315 {
 316         struct posix_acl *acl;
 317         int rc;
 318
 319         if (S_ISLNK(inode->i_mode))
 320                 return -EOPNOTSUPP;
 321         acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
 322         if (IS_ERR(acl) || !acl)
 323                 return PTR_ERR(acl);
 324         rc = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 325         if (rc)
 326                 return rc;
 327         rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, acl);
 328         posix_acl_release(acl);
 329         return rc;
 330 }
 331
 332 static size_t jffs2_acl_access_listxattr(struct dentry *dentry, char *list,
 333                 size_t list_size, const char *name, size_t name_len, int type)
 334 {
 335         const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
 336
 337         if (list && retlen <= list_size)
 338                 strcpy(list, POSIX_ACL_XATTR_ACCESS);
 339         return retlen;
 340 }
 341
 342 static size_t jffs2_acl_default_listxattr(struct dentry *dentry, char *list,
 343                 size_t list_size, const char *name, size_t name_len, int type)
 344 {
 345         const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
 346
 347         if (list && retlen <= list_size)
 348                 strcpy(list, POSIX_ACL_XATTR_DEFAULT);
 349         return retlen;
 350 }
 351
 352 static int jffs2_acl_getxattr(struct dentry *dentry, const char *name,
 353                 void *buffer, size_t size, int type)
 354 {
 355         struct posix_acl *acl;
 356         int rc;
 357
 358         if (name[0] != '\0')
 359                 return -EINVAL;
 360
 361         acl = jffs2_get_acl(dentry->d_inode, type);
 362         if (IS_ERR(acl))
 363                 return PTR_ERR(acl);
 364         if (!acl)
 365                 return -ENODATA;
 366         rc = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 367         posix_acl_release(acl);
 368
 369         return rc;
 370 }
 371
 372 static int jffs2_acl_setxattr(struct dentry *dentry, const char *name,
 373                 const void *value, size_t size, int flags, int type)
 374 {
 375         struct posix_acl *acl;
 376         int rc;
 377
 378         if (name[0] != '\0')
 379                 return -EINVAL;
 380         if (!inode_owner_or_capable(dentry->d_inode))
 381                 return -EPERM;
 382
 383         if (value) {
 384                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 385                 if (IS_ERR(acl))
 386                         return PTR_ERR(acl);
 387                 if (acl) {
 388                         rc = posix_acl_valid(acl);
 389                         if (rc)
 390                                 goto out;
 391                 }
 392         } else {
 393                 acl = NULL;
 394         }
 395         rc = jffs2_set_acl(dentry->d_inode, type, acl);
 396  out:
 397         posix_acl_release(acl);
 398         return rc;
 399 }
 400
 401 const struct xattr_handler jffs2_acl_access_xattr_handler = {
 402         .prefix = POSIX_ACL_XATTR_ACCESS,
 403         .flags  = ACL_TYPE_DEFAULT,
 404         .list   = jffs2_acl_access_listxattr,
 405         .get    = jffs2_acl_getxattr,
 406         .set    = jffs2_acl_setxattr,
 407 };
 408
 409 const struct xattr_handler jffs2_acl_default_xattr_handler = {
 410         .prefix = POSIX_ACL_XATTR_DEFAULT,
 411         .flags  = ACL_TYPE_DEFAULT,
 412         .list   = jffs2_acl_default_listxattr,
 413         .get    = jffs2_acl_getxattr,
 414         .set    = jffs2_acl_setxattr,
 415 };