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                                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
 128static 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
 175struct 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
 216static 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
 235static 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
 278int 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
 309int 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
 328int 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
 346static 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
 356static 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
 366static 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
 386static 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
 415const 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
 423const 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};
 430
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