linux/fs/jffs2/acl.c
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   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
  26static 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
  38static 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
  55static 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
 120static 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
 161struct 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
 202static 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
 221static 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
 264int 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
 295int 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
 314int 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
 332static 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
 342static 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
 352static 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(acl, buffer, size);
 367        posix_acl_release(acl);
 368
 369        return rc;
 370}
 371
 372static 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(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
 401const 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
 409const 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};
 416
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