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, bool rcu)
 146 {
 147         int name_index;
 148         char *value = NULL;
 149         struct posix_acl *acl;
 150         int retval;
 151
 152         if (rcu)
 153                 return ERR_PTR(-ECHILD);
 154
 155         switch (type) {
 156         case ACL_TYPE_ACCESS:
 157                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 158                 break;
 159         case ACL_TYPE_DEFAULT:
 160                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 161                 break;
 162         default:
 163                 BUG();
 164         }
 165         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
 166         if (retval > 0) {
 167                 value = kmalloc(retval, GFP_NOFS);
 168                 if (!value)
 169                         return ERR_PTR(-ENOMEM);
 170                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
 171         }
 172         if (retval > 0)
 173                 acl = ext4_acl_from_disk(value, retval);
 174         else if (retval == -ENODATA || retval == -ENOSYS)
 175                 acl = NULL;
 176         else
 177                 acl = ERR_PTR(retval);
 178         kfree(value);
 179
 180         return acl;
 181 }
 182
 183 /*
 184  * Set the access or default ACL of an inode.
 185  *
 186  * inode->i_mutex: down unless called from ext4_new_inode
 187  */
 188 static int
 189 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 190              struct posix_acl *acl, int xattr_flags)
 191 {
 192         int name_index;
 193         void *value = NULL;
 194         size_t size = 0;
 195         int error;
 196
 197         switch (type) {
 198         case ACL_TYPE_ACCESS:
 199                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 200                 break;
 201
 202         case ACL_TYPE_DEFAULT:
 203                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 204                 if (!S_ISDIR(inode->i_mode))
 205                         return acl ? -EACCES : 0;
 206                 break;
 207
 208         default:
 209                 return -EINVAL;
 210         }
 211         if (acl) {
 212                 value = ext4_acl_to_disk(acl, &size);
 213                 if (IS_ERR(value))
 214                         return (int)PTR_ERR(value);
 215         }
 216
 217         error = ext4_xattr_set_handle(handle, inode, name_index, "",
 218                                       value, size, xattr_flags);
 219
 220         kfree(value);
 221         if (!error)
 222                 set_cached_acl(inode, type, acl);
 223
 224         return error;
 225 }
 226
 227 int
 228 ext4_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
 229              struct posix_acl *acl, int type)
 230 {
 231         handle_t *handle;
 232         int error, credits, retries = 0;
 233         size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0;
 234         umode_t mode = inode->i_mode;
 235         int update_mode = 0;
 236
 237         error = dquot_initialize(inode);
 238         if (error)
 239                 return error;
 240 retry:
 241         error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */,
 242                                        &credits);
 243         if (error)
 244                 return error;
 245
 246         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
 247         if (IS_ERR(handle))
 248                 return PTR_ERR(handle);
 249         ext4_fc_start_update(inode);
 250
 251         if ((type == ACL_TYPE_ACCESS) && acl) {
 252                 error = posix_acl_update_mode(mnt_userns, inode, &mode, &acl);
 253                 if (error)
 254                         goto out_stop;
 255                 if (mode != inode->i_mode)
 256                         update_mode = 1;
 257         }
 258
 259         error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */);
 260         if (!error && update_mode) {
 261                 inode->i_mode = mode;
 262                 inode->i_ctime = current_time(inode);
 263                 error = ext4_mark_inode_dirty(handle, inode);
 264         }
 265 out_stop:
 266         ext4_journal_stop(handle);
 267         ext4_fc_stop_update(inode);
 268         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 269                 goto retry;
 270         return error;
 271 }
 272
 273 /*
 274  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 275  *
 276  * dir->i_mutex: down
 277  * inode->i_mutex: up (access to inode is still exclusive)
 278  */
 279 int
 280 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 281 {
 282         struct posix_acl *default_acl, *acl;
 283         int error;
 284
 285         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 286         if (error)
 287                 return error;
 288
 289         if (default_acl) {
 290                 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
 291                                        default_acl, XATTR_CREATE);
 292                 posix_acl_release(default_acl);
 293         } else {
 294                 inode->i_default_acl = NULL;
 295         }
 296         if (acl) {
 297                 if (!error)
 298                         error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
 299                                                acl, XATTR_CREATE);
 300                 posix_acl_release(acl);
 301         } else {
 302                 inode->i_acl = NULL;
 303         }
 304         return error;
 305 }