fs/fuse/acl.c

   1 /*
   2  * FUSE: Filesystem in Userspace
   3  * Copyright (C) 2016 Canonical Ltd. <seth.forshee@canonical.com>
   4  *
   5  * This program can be distributed under the terms of the GNU GPL.
   6  * See the file COPYING.
   7  */
   8
   9 #include "fuse_i.h"
  10
  11 #include <linux/posix_acl.h>
  12 #include <linux/posix_acl_xattr.h>
  13
  14 struct posix_acl *fuse_get_acl(struct inode *inode, int type)
  15 {
  16         struct fuse_conn *fc = get_fuse_conn(inode);
  17         int size;
  18         const char *name;
  19         void *value = NULL;
  20         struct posix_acl *acl;
  21
  22         if (fuse_is_bad(inode))
  23                 return ERR_PTR(-EIO);
  24
  25         if (!fc->posix_acl || fc->no_getxattr)
  26                 return NULL;
  27
  28         if (type == ACL_TYPE_ACCESS)
  29                 name = XATTR_NAME_POSIX_ACL_ACCESS;
  30         else if (type == ACL_TYPE_DEFAULT)
  31                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  32         else
  33                 return ERR_PTR(-EOPNOTSUPP);
  34
  35         value = kmalloc(PAGE_SIZE, GFP_KERNEL);
  36         if (!value)
  37                 return ERR_PTR(-ENOMEM);
  38         size = fuse_getxattr(inode, name, value, PAGE_SIZE);
  39         if (size > 0)
  40                 acl = posix_acl_from_xattr(fc->user_ns, value, size);
  41         else if ((size == 0) || (size == -ENODATA) ||
  42                  (size == -EOPNOTSUPP && fc->no_getxattr))
  43                 acl = NULL;
  44         else if (size == -ERANGE)
  45                 acl = ERR_PTR(-E2BIG);
  46         else
  47                 acl = ERR_PTR(size);
  48
  49         kfree(value);
  50         return acl;
  51 }
  52
  53 int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type)
  54 {
  55         struct fuse_conn *fc = get_fuse_conn(inode);
  56         const char *name;
  57         int ret;
  58
  59         if (fuse_is_bad(inode))
  60                 return -EIO;
  61
  62         if (!fc->posix_acl || fc->no_setxattr)
  63                 return -EOPNOTSUPP;
  64
  65         if (type == ACL_TYPE_ACCESS)
  66                 name = XATTR_NAME_POSIX_ACL_ACCESS;
  67         else if (type == ACL_TYPE_DEFAULT)
  68                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
  69         else
  70                 return -EINVAL;
  71
  72         if (acl) {
  73                 /*
  74                  * Fuse userspace is responsible for updating access
  75                  * permissions in the inode, if needed. fuse_setxattr
  76                  * invalidates the inode attributes, which will force
  77                  * them to be refreshed the next time they are used,
  78                  * and it also updates i_ctime.
  79                  */
  80                 size_t size = posix_acl_xattr_size(acl->a_count);
  81                 void *value;
  82
  83                 if (size > PAGE_SIZE)
  84                         return -E2BIG;
  85
  86                 value = kmalloc(size, GFP_KERNEL);
  87                 if (!value)
  88                         return -ENOMEM;
  89
  90                 ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);
  91                 if (ret < 0) {
  92                         kfree(value);
  93                         return ret;
  94                 }
  95
  96                 ret = fuse_setxattr(inode, name, value, size, 0);
  97                 kfree(value);
  98         } else {
  99                 ret = fuse_removexattr(inode, name);
 100         }
 101         forget_all_cached_acls(inode);
 102         fuse_invalidate_attr(inode);
 103
 104         return ret;
 105 }