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         switch (type) {
 182         case ACL_TYPE_ACCESS:
 183                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
 184                 break;
 185         case ACL_TYPE_DEFAULT:
 186                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
 187                 break;
 188         default:
 189                 BUG();
 190         }
 191         rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
 192         if (rc > 0) {
 193                 value = kmalloc(rc, GFP_KERNEL);
 194                 if (!value)
 195                         return ERR_PTR(-ENOMEM);
 196                 rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
 197         }
 198         if (rc > 0) {
 199                 acl = jffs2_acl_from_medium(value, rc);
 200         } else if (rc == -ENODATA || rc == -ENOSYS) {
 201                 acl = NULL;
 202         } else {
 203                 acl = ERR_PTR(rc);
 204         }
 205         kfree(value);
 206         if (!IS_ERR(acl))
 207                 set_cached_acl(inode, type, acl);
 208         return acl;
 209 }
 210
 211 static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
 212 {
 213         char *value = NULL;
 214         size_t size = 0;
 215         int rc;
 216
 217         if (acl) {
 218                 value = jffs2_acl_to_medium(acl, &size);
 219                 if (IS_ERR(value))
 220                         return PTR_ERR(value);
 221         }
 222         rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
 223         if (!value && rc == -ENODATA)
 224                 rc = 0;
 225         kfree(value);
 226
 227         return rc;
 228 }
 229
 230 int jffs2_set_acl(struct inode *inode, 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 = inode->i_mode;
 239                         rc = posix_acl_equiv_mode(acl, &mode);
 240                         if (rc < 0)
 241                                 return rc;
 242                         if (inode->i_mode != mode) {
 243                                 struct iattr attr;
 244
 245                                 attr.ia_valid = ATTR_MODE | ATTR_CTIME;
 246                                 attr.ia_mode = mode;
 247                                 attr.ia_ctime = CURRENT_TIME_SEC;
 248                                 rc = jffs2_do_setattr(inode, &attr);
 249                                 if (rc < 0)
 250                                         return rc;
 251                         }
 252                         if (rc == 0)
 253                                 acl = NULL;
 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
 270 int 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
 292 int 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 }