fs/ext4/acl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/ext4/acl.c
   4  *
   5  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   6  */
   7
   8 #include <linux/quotaops.h>
   9 #include "ext4_jbd2.h"
  10 #include "ext4.h"
  11 #include "xattr.h"
  12 #include "acl.h"
  13
  14 /*
  15  * Convert from filesystem to in-memory representation.
  16  */
  17 static struct posix_acl *
  18 ext4_acl_from_disk(const void *value, size_t size)
  19 {
  20         const char *end = (char *)value + size;
  21         int n, count;
  22         struct posix_acl *acl;
  23
  24         if (!value)
  25                 return NULL;
  26         if (size < sizeof(ext4_acl_header))
  27                  return ERR_PTR(-EINVAL);
  28         if (((ext4_acl_header *)value)->a_version !=
  29             cpu_to_le32(EXT4_ACL_VERSION))
  30                 return ERR_PTR(-EINVAL);
  31         value = (char *)value + sizeof(ext4_acl_header);
  32         count = ext4_acl_count(size);
  33         if (count < 0)
  34                 return ERR_PTR(-EINVAL);
  35         if (count == 0)
  36                 return NULL;
  37         acl = posix_acl_alloc(count, GFP_NOFS);
  38         if (!acl)
  39                 return ERR_PTR(-ENOMEM);
  40         for (n = 0; n < count; n++) {
  41                 ext4_acl_entry *entry =
  42                         (ext4_acl_entry *)value;
  43                 if ((char *)value + sizeof(ext4_acl_entry_short) > end)
  44                         goto fail;
  45                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  46                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  47
  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(ext4_acl_entry_short);
  55                         break;
  56
  57                 case ACL_USER:
  58                         value = (char *)value + sizeof(ext4_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(ext4_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 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
  92 {
  93         ext4_acl_header *ext_acl;
  94         char *e;
  95         size_t n;
  96
  97         *size = ext4_acl_size(acl->a_count);
  98         ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
  99                         sizeof(ext4_acl_entry), GFP_NOFS);
 100         if (!ext_acl)
 101                 return ERR_PTR(-ENOMEM);
 102         ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
 103         e = (char *)ext_acl + sizeof(ext4_acl_header);
 104         for (n = 0; n < acl->a_count; n++) {
 105                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 106                 ext4_acl_entry *entry = (ext4_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(ext4_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(ext4_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(ext4_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 operation get_posix_acl().
 141  *
 142  * inode->i_mutex: don't care
 143  */
 144 struct posix_acl *
 145 ext4_get_acl(struct inode *inode, int type)
 146 {
 147         int name_index;
 148         char *value = NULL;
 149         struct posix_acl *acl;
 150         int retval;
 151
 152         switch (type) {
 153         case ACL_TYPE_ACCESS:
 154                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 155                 break;
 156         case ACL_TYPE_DEFAULT:
 157                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 158                 break;
 159         default:
 160                 BUG();
 161         }
 162         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
 163         if (retval > 0) {
 164                 value = kmalloc(retval, GFP_NOFS);
 165                 if (!value)
 166                         return ERR_PTR(-ENOMEM);
 167                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
 168         }
 169         if (retval > 0)
 170                 acl = ext4_acl_from_disk(value, retval);
 171         else if (retval == -ENODATA || retval == -ENOSYS)
 172                 acl = NULL;
 173         else
 174                 acl = ERR_PTR(retval);
 175         kfree(value);
 176
 177         return acl;
 178 }
 179
 180 /*
 181  * Set the access or default ACL of an inode.
 182  *
 183  * inode->i_mutex: down unless called from ext4_new_inode
 184  */
 185 static int
 186 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 187              struct posix_acl *acl, int xattr_flags)
 188 {
 189         int name_index;
 190         void *value = NULL;
 191         size_t size = 0;
 192         int error;
 193
 194         switch (type) {
 195         case ACL_TYPE_ACCESS:
 196                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 197                 break;
 198
 199         case ACL_TYPE_DEFAULT:
 200                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 201                 if (!S_ISDIR(inode->i_mode))
 202                         return acl ? -EACCES : 0;
 203                 break;
 204
 205         default:
 206                 return -EINVAL;
 207         }
 208         if (acl) {
 209                 value = ext4_acl_to_disk(acl, &size);
 210                 if (IS_ERR(value))
 211                         return (int)PTR_ERR(value);
 212         }
 213
 214         error = ext4_xattr_set_handle(handle, inode, name_index, "",
 215                                       value, size, xattr_flags);
 216
 217         kfree(value);
 218         if (!error)
 219                 set_cached_acl(inode, type, acl);
 220
 221         return error;
 222 }
 223
 224 int
 225 ext4_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 226              struct posix_acl *acl, int type)
 227 {
 228         handle_t *handle;
 229         int error, credits, retries = 0;
 230         size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0;
 231         umode_t mode = inode->i_mode;
 232         int update_mode = 0;
 233
 234         error = dquot_initialize(inode);
 235         if (error)
 236                 return error;
 237 retry:
 238         error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */,
 239                                        &credits);
 240         if (error)
 241                 return error;
 242
 243         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
 244         if (IS_ERR(handle))
 245                 return PTR_ERR(handle);
 246         ext4_fc_start_update(inode);
 247
 248         if ((type == ACL_TYPE_ACCESS) && acl) {
 249                 error = posix_acl_update_mode(mnt_userns, inode, &mode, &acl);
 250                 if (error)
 251                         goto out_stop;
 252                 if (mode != inode->i_mode)
 253                         update_mode = 1;
 254         }
 255
 256         error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */);
 257         if (!error && update_mode) {
 258                 inode->i_mode = mode;
 259                 inode->i_ctime = current_time(inode);
 260                 error = ext4_mark_inode_dirty(handle, inode);
 261         }
 262 out_stop:
 263         ext4_journal_stop(handle);
 264         ext4_fc_stop_update(inode);
 265         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 266                 goto retry;
 267         return error;
 268 }
 269
 270 /*
 271  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 272  *
 273  * dir->i_mutex: down
 274  * inode->i_mutex: up (access to inode is still exclusive)
 275  */
 276 int
 277 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 278 {
 279         struct posix_acl *default_acl, *acl;
 280         int error;
 281
 282         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 283         if (error)
 284                 return error;
 285
 286         if (default_acl) {
 287                 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
 288                                        default_acl, XATTR_CREATE);
 289                 posix_acl_release(default_acl);
 290         } else {
 291                 inode->i_default_acl = NULL;
 292         }
 293         if (acl) {
 294                 if (!error)
 295                         error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
 296                                                acl, XATTR_CREATE);
 297                 posix_acl_release(acl);
 298         } else {
 299                 inode->i_acl = NULL;
 300         }
 301         return error;
 302 }