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(struct_size(header, a_entries, acl->a_count),
 137                        GFP_KERNEL);
 138        if (!header)
 139                return ERR_PTR(-ENOMEM);
 140        header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
 141        e = header + 1;
 142        for (i=0; i < acl->a_count; i++) {
 143                const struct posix_acl_entry *acl_e = &acl->a_entries[i];
 144                entry = e;
 145                entry->e_tag = cpu_to_je16(acl_e->e_tag);
 146                entry->e_perm = cpu_to_je16(acl_e->e_perm);
 147                switch(acl_e->e_tag) {
 148                        case ACL_USER:
 149                                entry->e_id = cpu_to_je32(
 150                                        from_kuid(&init_user_ns, acl_e->e_uid));
 151                                e += sizeof(struct jffs2_acl_entry);
 152                                break;
 153                        case ACL_GROUP:
 154                                entry->e_id = cpu_to_je32(
 155                                        from_kgid(&init_user_ns, acl_e->e_gid));
 156                                e += sizeof(struct jffs2_acl_entry);
 157                                break;
 158
 159                        case ACL_USER_OBJ:
 160                        case ACL_GROUP_OBJ:
 161                        case ACL_MASK:
 162                        case ACL_OTHER:
 163                                e += sizeof(struct jffs2_acl_entry_short);
 164                                break;
 165
 166                        default:
 167                                goto fail;
 168                }
 169        }
 170        return header;
 171 fail:
 172        kfree(header);
 173        return ERR_PTR(-EINVAL);
 174}
 175
 176struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
 177{
 178        struct posix_acl *acl;
 179        char *value = NULL;
 180        int rc, xprefix;
 181
 182        switch (type) {
 183        case ACL_TYPE_ACCESS:
 184                xprefix = JFFS2_XPREFIX_ACL_ACCESS;
 185                break;
 186        case ACL_TYPE_DEFAULT:
 187                xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
 188                break;
 189        default:
 190                BUG();
 191        }
 192        rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
 193        if (rc > 0) {
 194                value = kmalloc(rc, GFP_KERNEL);
 195                if (!value)
 196                        return ERR_PTR(-ENOMEM);
 197                rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
 198        }
 199        if (rc > 0) {
 200                acl = jffs2_acl_from_medium(value, rc);
 201        } else if (rc == -ENODATA || rc == -ENOSYS) {
 202                acl = NULL;
 203        } else {
 204                acl = ERR_PTR(rc);
 205        }
 206        kfree(value);
 207        return acl;
 208}
 209
 210static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
 211{
 212        char *value = NULL;
 213        size_t size = 0;
 214        int rc;
 215
 216        if (acl) {
 217                value = jffs2_acl_to_medium(acl, &size);
 218                if (IS_ERR(value))
 219                        return PTR_ERR(value);
 220        }
 221        rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
 222        if (!value && rc == -ENODATA)
 223                rc = 0;
 224        kfree(value);
 225
 226        return rc;
 227}
 228
 229int jffs2_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 230                  struct posix_acl *acl, int type)
 231{
 232        int rc, xprefix;
 233
 234        switch (type) {
 235        case ACL_TYPE_ACCESS:
 236                xprefix = JFFS2_XPREFIX_ACL_ACCESS;
 237                if (acl) {
 238                        umode_t mode;
 239
 240                        rc = posix_acl_update_mode(&init_user_ns, inode, &mode,
 241                                                   &acl);
 242                        if (rc)
 243                                return rc;
 244                        if (inode->i_mode != mode) {
 245                                struct iattr attr;
 246
 247                                attr.ia_valid = ATTR_MODE | ATTR_CTIME;
 248                                attr.ia_mode = mode;
 249                                attr.ia_ctime = current_time(inode);
 250                                rc = jffs2_do_setattr(inode, &attr);
 251                                if (rc < 0)
 252                                        return rc;
 253                        }
 254                }
 255                break;
 256        case ACL_TYPE_DEFAULT:
 257                xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
 258                if (!S_ISDIR(inode->i_mode))
 259                        return acl ? -EACCES : 0;
 260                break;
 261        default:
 262                return -EINVAL;
 263        }
 264        rc = __jffs2_set_acl(inode, xprefix, acl);
 265        if (!rc)
 266                set_cached_acl(inode, type, acl);
 267        return rc;
 268}
 269
 270int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
 271{
 272        struct posix_acl *default_acl, *acl;
 273        int rc;
 274
 275        cache_no_acl(inode);
 276
 277        rc = posix_acl_create(dir_i, i_mode, &default_acl, &acl);
 278        if (rc)
 279                return rc;
 280
 281        if (default_acl) {
 282                set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 283                posix_acl_release(default_acl);
 284        }
 285        if (acl) {
 286                set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 287                posix_acl_release(acl);
 288        }
 289        return 0;
 290}
 291
 292int jffs2_init_acl_post(struct inode *inode)
 293{
 294        int rc;
 295
 296        if (inode->i_default_acl) {
 297                rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
 298                if (rc)
 299                        return rc;
 300        }
 301
 302        if (inode->i_acl) {
 303                rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
 304                if (rc)
 305                        return rc;
 306        }
 307
 308        return 0;
 309}
 310
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