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alistair23-linux/fs/9p/acl.c
Eric W. Biederman 5f3a4a28ec userns: Pass a userns parameter into posix_acl_to_xattr and posix_acl_from_xattr 
- Pass the user namespace the uid and gid values in the xattr are stored
   in into posix_acl_from_xattr.

 - Pass the user namespace kuid and kgid values should be converted into
   when storing uid and gid values in an xattr in posix_acl_to_xattr.

- Modify all callers of posix_acl_from_xattr and posix_acl_to_xattr to
  pass in &init_user_ns.

In the short term this change is not strictly needed but it makes the
code clearer.  In the longer term this change is necessary to be able to
mount filesystems outside of the initial user namespace that natively
store posix acls in the linux xattr format.

Cc: Theodore Tso <tytso@mit.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-09-18 01:01:35 -07:00

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/*
* Copyright IBM Corporation, 2010
* Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2.1 of the GNU Lesser General Public License
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/posix_acl_xattr.h>
#include "xattr.h"
#include "acl.h"
#include "v9fs.h"
#include "v9fs_vfs.h"
static struct posix_acl *__v9fs_get_acl(struct p9_fid *fid, char *name)
{
ssize_t size;
void *value = NULL;
struct posix_acl *acl = NULL;
size = v9fs_fid_xattr_get(fid, name, NULL, 0);
if (size > 0) {
value = kzalloc(size, GFP_NOFS);
if (!value)
return ERR_PTR(-ENOMEM);
size = v9fs_fid_xattr_get(fid, name, value, size);
if (size > 0) {
acl = posix_acl_from_xattr(&init_user_ns, value, size);
if (IS_ERR(acl))
goto err_out;
}
} else if (size == -ENODATA || size == 0 ||
size == -ENOSYS || size == -EOPNOTSUPP) {
acl = NULL;
} else
acl = ERR_PTR(-EIO);
err_out:
kfree(value);
return acl;
}
int v9fs_get_acl(struct inode *inode, struct p9_fid *fid)
{
int retval = 0;
struct posix_acl *pacl, *dacl;
struct v9fs_session_info *v9ses;
v9ses = v9fs_inode2v9ses(inode);
if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
set_cached_acl(inode, ACL_TYPE_DEFAULT, NULL);
set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
return 0;
}
/* get the default/access acl values and cache them */
dacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_DEFAULT);
pacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_ACCESS);
if (!IS_ERR(dacl) && !IS_ERR(pacl)) {
set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
set_cached_acl(inode, ACL_TYPE_ACCESS, pacl);
} else
retval = -EIO;
if (!IS_ERR(dacl))
posix_acl_release(dacl);
if (!IS_ERR(pacl))
posix_acl_release(pacl);
return retval;
}
static struct posix_acl *v9fs_get_cached_acl(struct inode *inode, int type)
{
struct posix_acl *acl;
/*
* 9p Always cache the acl value when
* instantiating the inode (v9fs_inode_from_fid)
*/
acl = get_cached_acl(inode, type);
BUG_ON(acl == ACL_NOT_CACHED);
return acl;
}
struct posix_acl *v9fs_iop_get_acl(struct inode *inode, int type)
{
struct v9fs_session_info *v9ses;
v9ses = v9fs_inode2v9ses(inode);
if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
/*
* On access = client and acl = on mode get the acl
* values from the server
*/
return NULL;
}
return v9fs_get_cached_acl(inode, type);
}
static int v9fs_set_acl(struct dentry *dentry, int type, struct posix_acl *acl)
{
int retval;
char *name;
size_t size;
void *buffer;
struct inode *inode = dentry->d_inode;
set_cached_acl(inode, type, acl);
if (!acl)
return 0;
/* Set a setxattr request to server */
size = posix_acl_xattr_size(acl->a_count);
buffer = kmalloc(size, GFP_KERNEL);
if (!buffer)
return -ENOMEM;
retval = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
if (retval < 0)
goto err_free_out;
switch (type) {
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
break;
case ACL_TYPE_DEFAULT:
name = POSIX_ACL_XATTR_DEFAULT;
break;
default:
BUG();
}
retval = v9fs_xattr_set(dentry, name, buffer, size, 0);
err_free_out:
kfree(buffer);
return retval;
}
int v9fs_acl_chmod(struct dentry *dentry)
{
int retval = 0;
struct posix_acl *acl;
struct inode *inode = dentry->d_inode;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
if (acl) {
retval = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
if (retval)
return retval;
retval = v9fs_set_acl(dentry, ACL_TYPE_ACCESS, acl);
posix_acl_release(acl);
}
return retval;
}
int v9fs_set_create_acl(struct dentry *dentry,
struct posix_acl **dpacl, struct posix_acl **pacl)
{
if (dentry) {
v9fs_set_acl(dentry, ACL_TYPE_DEFAULT, *dpacl);
v9fs_set_acl(dentry, ACL_TYPE_ACCESS, *pacl);
}
posix_acl_release(*dpacl);
posix_acl_release(*pacl);
*dpacl = *pacl = NULL;
return 0;
}
int v9fs_acl_mode(struct inode *dir, umode_t *modep,
struct posix_acl **dpacl, struct posix_acl **pacl)
{
int retval = 0;
umode_t mode = *modep;
struct posix_acl *acl = NULL;
if (!S_ISLNK(mode)) {
acl = v9fs_get_cached_acl(dir, ACL_TYPE_DEFAULT);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (!acl)
mode &= ~current_umask();
}
if (acl) {
if (S_ISDIR(mode))
*dpacl = posix_acl_dup(acl);
retval = posix_acl_create(&acl, GFP_NOFS, &mode);
if (retval < 0)
return retval;
if (retval > 0)
*pacl = acl;
else
posix_acl_release(acl);
}
*modep = mode;
return 0;
}
static int v9fs_remote_get_acl(struct dentry *dentry, const char *name,
void *buffer, size_t size, int type)
{
char *full_name;
switch (type) {
case ACL_TYPE_ACCESS:
full_name = POSIX_ACL_XATTR_ACCESS;
break;
case ACL_TYPE_DEFAULT:
full_name = POSIX_ACL_XATTR_DEFAULT;
break;
default:
BUG();
}
return v9fs_xattr_get(dentry, full_name, buffer, size);
}
static int v9fs_xattr_get_acl(struct dentry *dentry, const char *name,
void *buffer, size_t size, int type)
{
struct v9fs_session_info *v9ses;
struct posix_acl *acl;
int error;
if (strcmp(name, "") != 0)
return -EINVAL;
v9ses = v9fs_dentry2v9ses(dentry);
/*
* We allow set/get/list of acl when access=client is not specified
*/
if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
return v9fs_remote_get_acl(dentry, name, buffer, size, type);
acl = v9fs_get_cached_acl(dentry->d_inode, type);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl == NULL)
return -ENODATA;
error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
posix_acl_release(acl);
return error;
}
static int v9fs_remote_set_acl(struct dentry *dentry, const char *name,
const void *value, size_t size,
int flags, int type)
{
char *full_name;
switch (type) {
case ACL_TYPE_ACCESS:
full_name = POSIX_ACL_XATTR_ACCESS;
break;
case ACL_TYPE_DEFAULT:
full_name = POSIX_ACL_XATTR_DEFAULT;
break;
default:
BUG();
}
return v9fs_xattr_set(dentry, full_name, value, size, flags);
}
static int v9fs_xattr_set_acl(struct dentry *dentry, const char *name,
const void *value, size_t size,
int flags, int type)
{
int retval;
struct posix_acl *acl;
struct v9fs_session_info *v9ses;
struct inode *inode = dentry->d_inode;
if (strcmp(name, "") != 0)
return -EINVAL;
v9ses = v9fs_dentry2v9ses(dentry);
/*
* set the attribute on the remote. Without even looking at the
* xattr value. We leave it to the server to validate
*/
if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
return v9fs_remote_set_acl(dentry, name,
value, size, flags, type);
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
if (!inode_owner_or_capable(inode))
return -EPERM;
if (value) {
/* update the cached acl value */
acl = posix_acl_from_xattr(&init_user_ns, value, size);
if (IS_ERR(acl))
return PTR_ERR(acl);
else if (acl) {
retval = posix_acl_valid(acl);
if (retval)
goto err_out;
}
} else
acl = NULL;
switch (type) {
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
if (acl) {
umode_t mode = inode->i_mode;
retval = posix_acl_equiv_mode(acl, &mode);
if (retval < 0)
goto err_out;
else {
struct iattr iattr;
if (retval == 0) {
/*
* ACL can be represented
* by the mode bits. So don't
* update ACL.
*/
acl = NULL;
value = NULL;
size = 0;
}
/* Updte the mode bits */
iattr.ia_mode = ((mode & S_IALLUGO) |
(inode->i_mode & ~S_IALLUGO));
iattr.ia_valid = ATTR_MODE;
/* FIXME should we update ctime ?
* What is the following setxattr update the
* mode ?
*/
v9fs_vfs_setattr_dotl(dentry, &iattr);
}
}
break;
case ACL_TYPE_DEFAULT:
name = POSIX_ACL_XATTR_DEFAULT;
if (!S_ISDIR(inode->i_mode)) {
retval = acl ? -EINVAL : 0;
goto err_out;
}
break;
default:
BUG();
}
retval = v9fs_xattr_set(dentry, name, value, size, flags);
if (!retval)
set_cached_acl(inode, type, acl);
err_out:
posix_acl_release(acl);
return retval;
}
const struct xattr_handler v9fs_xattr_acl_access_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.flags = ACL_TYPE_ACCESS,
.get = v9fs_xattr_get_acl,
.set = v9fs_xattr_set_acl,
};
const struct xattr_handler v9fs_xattr_acl_default_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.flags = ACL_TYPE_DEFAULT,
.get = v9fs_xattr_get_acl,
.set = v9fs_xattr_set_acl,
};
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