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(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
 176 struct posix_acl *jffs2_get_acl(struct inode *inode, int type, bool rcu)
 177 {
 178         struct posix_acl *acl;
 179         char *value = NULL;
 180         int rc, xprefix;
 181
 182         if (rcu)
 183                 return ERR_PTR(-ECHILD);
 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         kfree(value);
 210         return acl;
 211 }
 212
 213 static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
 214 {
 215         char *value = NULL;
 216         size_t size = 0;
 217         int rc;
 218
 219         if (acl) {
 220                 value = jffs2_acl_to_medium(acl, &size);
 221                 if (IS_ERR(value))
 222                         return PTR_ERR(value);
 223         }
 224         rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
 225         if (!value && rc == -ENODATA)
 226                 rc = 0;
 227         kfree(value);
 228
 229         return rc;
 230 }
 231
 232 int jffs2_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 233                   struct posix_acl *acl, int type)
 234 {
 235         int rc, xprefix;
 236
 237         switch (type) {
 238         case ACL_TYPE_ACCESS:
 239                 xprefix = JFFS2_XPREFIX_ACL_ACCESS;
 240                 if (acl) {
 241                         umode_t mode;
 242
 243                         rc = posix_acl_update_mode(&init_user_ns, inode, &mode,
 244                                                    &acl);
 245                         if (rc)
 246                                 return rc;
 247                         if (inode->i_mode != mode) {
 248                                 struct iattr attr;
 249
 250                                 attr.ia_valid = ATTR_MODE | ATTR_CTIME;
 251                                 attr.ia_mode = mode;
 252                                 attr.ia_ctime = current_time(inode);
 253                                 rc = jffs2_do_setattr(inode, &attr);
 254                                 if (rc < 0)
 255                                         return rc;
 256                         }
 257                 }
 258                 break;
 259         case ACL_TYPE_DEFAULT:
 260                 xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
 261                 if (!S_ISDIR(inode->i_mode))
 262                         return acl ? -EACCES : 0;
 263                 break;
 264         default:
 265                 return -EINVAL;
 266         }
 267         rc = __jffs2_set_acl(inode, xprefix, acl);
 268         if (!rc)
 269                 set_cached_acl(inode, type, acl);
 270         return rc;
 271 }
 272
 273 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
 274 {
 275         struct posix_acl *default_acl, *acl;
 276         int rc;
 277
 278         cache_no_acl(inode);
 279
 280         rc = posix_acl_create(dir_i, i_mode, &default_acl, &acl);
 281         if (rc)
 282                 return rc;
 283
 284         if (default_acl) {
 285                 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 286                 posix_acl_release(default_acl);
 287         }
 288         if (acl) {
 289                 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 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 }