fs/ext2/acl.c

   1 /*
   2  * linux/fs/ext2/acl.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5  */
   6
   7 #include <linux/init.h>
   8 #include <linux/sched.h>
   9 #include <linux/slab.h>
  10 #include <linux/fs.h>
  11 #include "ext2.h"
  12 #include "xattr.h"
  13 #include "acl.h"
  14
  15 /*
  16  * Convert from filesystem to in-memory representation.
  17  */
  18 static struct posix_acl *
  19 ext2_acl_from_disk(const void *value, size_t size)
  20 {
  21         const char *end = (char *)value + size;
  22         int n, count;
  23         struct posix_acl *acl;
  24
  25         if (!value)
  26                 return NULL;
  27         if (size < sizeof(ext2_acl_header))
  28                  return ERR_PTR(-EINVAL);
  29         if (((ext2_acl_header *)value)->a_version !=
  30             cpu_to_le32(EXT2_ACL_VERSION))
  31                 return ERR_PTR(-EINVAL);
  32         value = (char *)value + sizeof(ext2_acl_header);
  33         count = ext2_acl_count(size);
  34         if (count < 0)
  35                 return ERR_PTR(-EINVAL);
  36         if (count == 0)
  37                 return NULL;
  38         acl = posix_acl_alloc(count, GFP_KERNEL);
  39         if (!acl)
  40                 return ERR_PTR(-ENOMEM);
  41         for (n=0; n < count; n++) {
  42                 ext2_acl_entry *entry =
  43                         (ext2_acl_entry *)value;
  44                 if ((char *)value + sizeof(ext2_acl_entry_short) > end)
  45                         goto fail;
  46                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  47                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  48                 switch(acl->a_entries[n].e_tag) {
  49                         case ACL_USER_OBJ:
  50                         case ACL_GROUP_OBJ:
  51                         case ACL_MASK:
  52                         case ACL_OTHER:
  53                                 value = (char *)value +
  54                                         sizeof(ext2_acl_entry_short);
  55                                 break;
  56
  57                         case ACL_USER:
  58                                 value = (char *)value + sizeof(ext2_acl_entry);
  59                                 if ((char *)value > end)
  60                                         goto fail;
  61                                 acl->a_entries[n].e_uid =
  62                                         make_kuid(&init_user_ns,
  63                                                   le32_to_cpu(entry->e_id));
  64                                 break;
  65                         case ACL_GROUP:
  66                                 value = (char *)value + sizeof(ext2_acl_entry);
  67                                 if ((char *)value > end)
  68                                         goto fail;
  69                                 acl->a_entries[n].e_gid =
  70                                         make_kgid(&init_user_ns,
  71                                                   le32_to_cpu(entry->e_id));
  72                                 break;
  73
  74                         default:
  75                                 goto fail;
  76                 }
  77         }
  78         if (value != end)
  79                 goto fail;
  80         return acl;
  81
  82 fail:
  83         posix_acl_release(acl);
  84         return ERR_PTR(-EINVAL);
  85 }
  86
  87 /*
  88  * Convert from in-memory to filesystem representation.
  89  */
  90 static void *
  91 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
  92 {
  93         ext2_acl_header *ext_acl;
  94         char *e;
  95         size_t n;
  96
  97         *size = ext2_acl_size(acl->a_count);
  98         ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
  99                         sizeof(ext2_acl_entry), GFP_KERNEL);
 100         if (!ext_acl)
 101                 return ERR_PTR(-ENOMEM);
 102         ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
 103         e = (char *)ext_acl + sizeof(ext2_acl_header);
 104         for (n=0; n < acl->a_count; n++) {
 105                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 106                 ext2_acl_entry *entry = (ext2_acl_entry *)e;
 107                 entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 108                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
 109                 switch(acl_e->e_tag) {
 110                         case ACL_USER:
 111                                 entry->e_id = cpu_to_le32(
 112                                         from_kuid(&init_user_ns, acl_e->e_uid));
 113                                 e += sizeof(ext2_acl_entry);
 114                                 break;
 115                         case ACL_GROUP:
 116                                 entry->e_id = cpu_to_le32(
 117                                         from_kgid(&init_user_ns, acl_e->e_gid));
 118                                 e += sizeof(ext2_acl_entry);
 119                                 break;
 120
 121                         case ACL_USER_OBJ:
 122                         case ACL_GROUP_OBJ:
 123                         case ACL_MASK:
 124                         case ACL_OTHER:
 125                                 e += sizeof(ext2_acl_entry_short);
 126                                 break;
 127
 128                         default:
 129                                 goto fail;
 130                 }
 131         }
 132         return (char *)ext_acl;
 133
 134 fail:
 135         kfree(ext_acl);
 136         return ERR_PTR(-EINVAL);
 137 }
 138
 139 /*
 140  * inode->i_mutex: don't care
 141  */
 142 struct posix_acl *
 143 ext2_get_acl(struct inode *inode, int type)
 144 {
 145         int name_index;
 146         char *value = NULL;
 147         struct posix_acl *acl;
 148         int retval;
 149
 150         switch (type) {
 151         case ACL_TYPE_ACCESS:
 152                 name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 153                 break;
 154         case ACL_TYPE_DEFAULT:
 155                 name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 156                 break;
 157         default:
 158                 BUG();
 159         }
 160         retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
 161         if (retval > 0) {
 162                 value = kmalloc(retval, GFP_KERNEL);
 163                 if (!value)
 164                         return ERR_PTR(-ENOMEM);
 165                 retval = ext2_xattr_get(inode, name_index, "", value, retval);
 166         }
 167         if (retval > 0)
 168                 acl = ext2_acl_from_disk(value, retval);
 169         else if (retval == -ENODATA || retval == -ENOSYS)
 170                 acl = NULL;
 171         else
 172                 acl = ERR_PTR(retval);
 173         kfree(value);
 174
 175         if (!IS_ERR(acl))
 176                 set_cached_acl(inode, type, acl);
 177
 178         return acl;
 179 }
 180
 181 /*
 182  * inode->i_mutex: down
 183  */
 184 int
 185 ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 186 {
 187         int name_index;
 188         void *value = NULL;
 189         size_t size = 0;
 190         int error;
 191
 192         switch(type) {
 193                 case ACL_TYPE_ACCESS:
 194                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 195                         if (acl) {
 196                                 error = posix_acl_equiv_mode(acl, &inode->i_mode);
 197                                 if (error < 0)
 198                                         return error;
 199                                 else {
 200                                         inode->i_ctime = CURRENT_TIME_SEC;
 201                                         mark_inode_dirty(inode);
 202                                         if (error == 0)
 203                                                 acl = NULL;
 204                                 }
 205                         }
 206                         break;
 207
 208                 case ACL_TYPE_DEFAULT:
 209                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 210                         if (!S_ISDIR(inode->i_mode))
 211                                 return acl ? -EACCES : 0;
 212                         break;
 213
 214                 default:
 215                         return -EINVAL;
 216         }
 217         if (acl) {
 218                 value = ext2_acl_to_disk(acl, &size);
 219                 if (IS_ERR(value))
 220                         return (int)PTR_ERR(value);
 221         }
 222
 223         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
 224
 225         kfree(value);
 226         if (!error)
 227                 set_cached_acl(inode, type, acl);
 228         return error;
 229 }
 230
 231 /*
 232  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 233  *
 234  * dir->i_mutex: down
 235  * inode->i_mutex: up (access to inode is still exclusive)
 236  */
 237 int
 238 ext2_init_acl(struct inode *inode, struct inode *dir)
 239 {
 240         struct posix_acl *default_acl, *acl;
 241         int error;
 242
 243         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 244         if (error)
 245                 return error;
 246
 247         if (default_acl) {
 248                 error = ext2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
 249                 posix_acl_release(default_acl);
 250         }
 251         if (acl) {
 252                 if (!error)
 253                         error = ext2_set_acl(inode, acl, ACL_TYPE_ACCESS);
 254                 posix_acl_release(acl);
 255         }
 256         return error;
 257 }