fs/btrfs/acl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Red Hat.  All rights reserved.
   4  */
   5
   6 #include <linux/fs.h>
   7 #include <linux/string.h>
   8 #include <linux/xattr.h>
   9 #include <linux/posix_acl_xattr.h>
  10 #include <linux/posix_acl.h>
  11 #include <linux/sched.h>
  12 #include <linux/sched/mm.h>
  13 #include <linux/slab.h>
  14 #include "ctree.h"
  15 #include "xattr.h"
  16 #include "acl.h"
  17
  18 struct posix_acl *btrfs_get_acl(struct inode *inode, int type, bool rcu)
  19 {
  20         int size;
  21         const char *name;
  22         char *value = NULL;
  23         struct posix_acl *acl;
  24
  25         if (rcu)
  26                 return ERR_PTR(-ECHILD);
  27
  28         switch (type) {
  29         case ACL_TYPE_ACCESS:
  30                 name = XATTR_NAME_POSIX_ACL_ACCESS;
  31                 break;
  32         case ACL_TYPE_DEFAULT:
  33                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  34                 break;
  35         default:
  36                 return ERR_PTR(-EINVAL);
  37         }
  38
  39         size = btrfs_getxattr(inode, name, NULL, 0);
  40         if (size > 0) {
  41                 value = kzalloc(size, GFP_KERNEL);
  42                 if (!value)
  43                         return ERR_PTR(-ENOMEM);
  44                 size = btrfs_getxattr(inode, name, value, size);
  45         }
  46         if (size > 0)
  47                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
  48         else if (size == -ENODATA || size == 0)
  49                 acl = NULL;
  50         else
  51                 acl = ERR_PTR(size);
  52         kfree(value);
  53
  54         return acl;
  55 }
  56
  57 int __btrfs_set_acl(struct btrfs_trans_handle *trans, struct inode *inode,
  58                     struct posix_acl *acl, int type)
  59 {
  60         int ret, size = 0;
  61         const char *name;
  62         char *value = NULL;
  63
  64         switch (type) {
  65         case ACL_TYPE_ACCESS:
  66                 name = XATTR_NAME_POSIX_ACL_ACCESS;
  67                 break;
  68         case ACL_TYPE_DEFAULT:
  69                 if (!S_ISDIR(inode->i_mode))
  70                         return acl ? -EINVAL : 0;
  71                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  72                 break;
  73         default:
  74                 return -EINVAL;
  75         }
  76
  77         if (acl) {
  78                 unsigned int nofs_flag;
  79
  80                 size = posix_acl_xattr_size(acl->a_count);
  81                 /*
  82                  * We're holding a transaction handle, so use a NOFS memory
  83                  * allocation context to avoid deadlock if reclaim happens.
  84                  */
  85                 nofs_flag = memalloc_nofs_save();
  86                 value = kmalloc(size, GFP_KERNEL);
  87                 memalloc_nofs_restore(nofs_flag);
  88                 if (!value) {
  89                         ret = -ENOMEM;
  90                         goto out;
  91                 }
  92
  93                 ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
  94                 if (ret < 0)
  95                         goto out;
  96         }
  97
  98         if (trans)
  99                 ret = btrfs_setxattr(trans, inode, name, value, size, 0);
 100         else
 101                 ret = btrfs_setxattr_trans(inode, name, value, size, 0);
 102
 103 out:
 104         kfree(value);
 105
 106         if (!ret)
 107                 set_cached_acl(inode, type, acl);
 108
 109         return ret;
 110 }
 111
 112 int btrfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 113                   struct posix_acl *acl, int type)
 114 {
 115         int ret;
 116         struct inode *inode = d_inode(dentry);
 117         umode_t old_mode = inode->i_mode;
 118
 119         if (type == ACL_TYPE_ACCESS && acl) {
 120                 ret = posix_acl_update_mode(idmap, inode,
 121                                             &inode->i_mode, &acl);
 122                 if (ret)
 123                         return ret;
 124         }
 125         ret = __btrfs_set_acl(NULL, inode, acl, type);
 126         if (ret)
 127                 inode->i_mode = old_mode;
 128         return ret;
 129 }