mirror_zfs/include/linux/xattr_compat.h
Brian Behlendorf 4967a3eb9d Linux 4.5 compat: xattr list handler
The registered xattr .list handler was simplified in the 4.5 kernel
to only perform a permission check.  Given a dentry for the file it
must return a boolean indicating if the name is visible.  This
differs slightly from the previous APIs which also required the
function to copy the name in to the provided list and return its
size.  That is now all the responsibility of the caller.

This should be straight forward change to make to ZoL since we've
always required the caller to make the copy.  However, this was
slightly complicated by the need to support 3 older APIs.  Yes,
between 2.6.32 and 4.5 there are 4 versions of this interface!

Therefore, while the functional change in this patch is small it
includes significant cleanup to make the code understandable and
maintainable.  These changes include:

- Improved configure checks for .list, .get, and .set interfaces.
  - Interfaces checked from newest to oldest.
  - Strict checking for each possible known interface.
  - Configure fails when no known interface is available.
  - HAVE_*_XATTR_LIST renamed HAVE_XATTR_LIST_* for consistency
    with similar iops and fops configure checks.

- POSIX_ACL_XATTR_{DEFAULT|ACCESS} were removed forcing callers to
  move to their replacements, XATTR_NAME_POSIX_ACL_{DEFAULT|ACCESS}.
  Compatibility wrapper were added for old kernels.

- ZPL_XATTR_LIST_WRAPPER added which behaves the same as the existing
  ZPL_XATTR_{GET|SET} WRAPPERs.  Only the inode is guaranteed to be
  a valid pointer, passing NULL for the 'list' and 'name' variables
  is allowed and must be checked for.  All .list functions were
  updated to use the wrapper to aid readability.

- zpl_xattr_filldir() updated to use the .list function for its
  permission check which is consistent with the updated Linux 4.5
  interface.  If a .list function is registered it should return 0
  to indicate a name should be skipped, if there is no registered
  function the name will be added.

- Additional documentation from xattr(7) describing the correct
  behavior for each namespace was added before the relevant handlers.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Issue #4228
2016-01-20 11:36:56 -08:00

225 lines
6.5 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
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*
* When distributing Covered Code, include this CDDL HEADER in each
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* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (C) 2011 Lawrence Livermore National Security, LLC.
*/
#ifndef _ZFS_XATTR_H
#define _ZFS_XATTR_H
#include <linux/posix_acl_xattr.h>
/*
* 2.6.35 API change,
* The const keyword was added to the 'struct xattr_handler' in the
* generic Linux super_block structure. To handle this we define an
* appropriate xattr_handler_t typedef which can be used. This was
* the preferred solution because it keeps the code clean and readable.
*/
#ifdef HAVE_CONST_XATTR_HANDLER
typedef const struct xattr_handler xattr_handler_t;
#else
typedef struct xattr_handler xattr_handler_t;
#endif
/*
* 3.7 API change,
* Preferred XATTR_NAME_* definitions introduced, these are mapped to
* the previous definitions for older kernels.
*/
#ifndef XATTR_NAME_POSIX_ACL_DEFAULT
#define XATTR_NAME_POSIX_ACL_DEFAULT POSIX_ACL_XATTR_DEFAULT
#endif
#ifndef XATTR_NAME_POSIX_ACL_ACCESS
#define XATTR_NAME_POSIX_ACL_ACCESS POSIX_ACL_XATTR_ACCESS
#endif
/*
* 4.5 API change,
*/
#if defined(HAVE_XATTR_LIST_SIMPLE)
#define ZPL_XATTR_LIST_WRAPPER(fn) \
static bool \
fn(struct dentry *dentry) \
{ \
return (!!__ ## fn(dentry->d_inode, NULL, 0, NULL, 0)); \
}
/*
* 4.4 API change,
*/
#elif defined(HAVE_XATTR_LIST_DENTRY)
#define ZPL_XATTR_LIST_WRAPPER(fn) \
static size_t \
fn(struct dentry *dentry, char *list, size_t list_size, \
const char *name, size_t name_len, int type) \
{ \
return (__ ## fn(dentry->d_inode, \
list, list_size, name, name_len)); \
}
/*
* 2.6.33 API change,
*/
#elif defined(HAVE_XATTR_LIST_HANDLER)
#define ZPL_XATTR_LIST_WRAPPER(fn) \
static size_t \
fn(const struct xattr_handler *handler, struct dentry *dentry, \
char *list, size_t list_size, const char *name, size_t name_len) \
{ \
return (__ ## fn(dentry->d_inode, \
list, list_size, name, name_len)); \
}
/*
* 2.6.32 API
*/
#elif defined(HAVE_XATTR_LIST_INODE)
#define ZPL_XATTR_LIST_WRAPPER(fn) \
static size_t \
fn(struct inode *ip, char *list, size_t list_size, \
const char *name, size_t name_len) \
{ \
return (__ ## fn(ip, list, list_size, name, name_len)); \
}
#endif
/*
* 4.4 API change,
* The xattr_handler->get() callback was changed to take a xattr_handler,
* and handler_flags argument was removed and should be accessed by
* handler->flags.
*/
#if defined(HAVE_XATTR_GET_HANDLER)
#define ZPL_XATTR_GET_WRAPPER(fn) \
static int \
fn(const struct xattr_handler *handler, struct dentry *dentry, \
const char *name, void *buffer, size_t size) \
{ \
return (__ ## fn(dentry->d_inode, name, buffer, size)); \
}
/*
* 2.6.33 API change,
* The xattr_handler->get() callback was changed to take a dentry
* instead of an inode, and a handler_flags argument was added.
*/
#elif defined(HAVE_XATTR_GET_DENTRY)
#define ZPL_XATTR_GET_WRAPPER(fn) \
static int \
fn(struct dentry *dentry, const char *name, void *buffer, size_t size, \
int unused_handler_flags) \
{ \
return (__ ## fn(dentry->d_inode, name, buffer, size)); \
}
/*
* 2.6.32 API
*/
#elif defined(HAVE_XATTR_GET_INODE)
#define ZPL_XATTR_GET_WRAPPER(fn) \
static int \
fn(struct inode *ip, const char *name, void *buffer, size_t size) \
{ \
return (__ ## fn(ip, name, buffer, size)); \
}
#endif
/*
* 4.4 API change,
* The xattr_handler->set() callback was changed to take a xattr_handler,
* and handler_flags argument was removed and should be accessed by
* handler->flags.
*/
#if defined(HAVE_XATTR_SET_HANDLER)
#define ZPL_XATTR_SET_WRAPPER(fn) \
static int \
fn(const struct xattr_handler *handler, struct dentry *dentry, \
const char *name, const void *buffer, size_t size, int flags) \
{ \
return (__ ## fn(dentry->d_inode, name, buffer, size, flags)); \
}
/*
* 2.6.33 API change,
* The xattr_handler->set() callback was changed to take a dentry
* instead of an inode, and a handler_flags argument was added.
*/
#elif defined(HAVE_XATTR_SET_DENTRY)
#define ZPL_XATTR_SET_WRAPPER(fn) \
static int \
fn(struct dentry *dentry, const char *name, const void *buffer, \
size_t size, int flags, int unused_handler_flags) \
{ \
return (__ ## fn(dentry->d_inode, name, buffer, size, flags)); \
}
/*
* 2.6.32 API
*/
#elif defined(HAVE_XATTR_SET_INODE)
#define ZPL_XATTR_SET_WRAPPER(fn) \
static int \
fn(struct inode *ip, const char *name, const void *buffer, \
size_t size, int flags) \
{ \
return (__ ## fn(ip, name, buffer, size, flags)); \
}
#endif
#ifdef HAVE_6ARGS_SECURITY_INODE_INIT_SECURITY
#define zpl_security_inode_init_security(ip, dip, qstr, nm, val, len) \
security_inode_init_security(ip, dip, qstr, nm, val, len)
#else
#define zpl_security_inode_init_security(ip, dip, qstr, nm, val, len) \
security_inode_init_security(ip, dip, nm, val, len)
#endif /* HAVE_6ARGS_SECURITY_INODE_INIT_SECURITY */
/*
* Linux 3.7 API change. posix_acl_{from,to}_xattr gained the user_ns
* parameter. For the HAVE_POSIX_ACL_FROM_XATTR_USERNS version the
* userns _may_ not be correct because it's used outside the RCU.
*/
#ifdef HAVE_POSIX_ACL_FROM_XATTR_USERNS
static inline struct posix_acl *
zpl_acl_from_xattr(const void *value, int size)
{
return (posix_acl_from_xattr(CRED()->user_ns, value, size));
}
static inline int
zpl_acl_to_xattr(struct posix_acl *acl, void *value, int size)
{
return (posix_acl_to_xattr(CRED()->user_ns, acl, value, size));
}
#else
static inline struct posix_acl *
zpl_acl_from_xattr(const void *value, int size)
{
return (posix_acl_from_xattr(value, size));
}
static inline int
zpl_acl_to_xattr(struct posix_acl *acl, void *value, int size)
{
return (posix_acl_to_xattr(acl, value, size));
}
#endif /* HAVE_POSIX_ACL_FROM_XATTR_USERNS */
#endif /* _ZFS_XATTR_H */