alistair23-linux/fs/9p/acl.c

/*
 * 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"
#include "fid.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, XATTR_NAME_POSIX_ACL_DEFAULT);
	pacl = __v9fs_get_acl(fid, XATTR_NAME_POSIX_ACL_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(is_uncached_acl(acl));
	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 p9_fid *fid, int type, struct posix_acl *acl)
{
	int retval;
	char *name;
	size_t size;
	void *buffer;
	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 = XATTR_NAME_POSIX_ACL_ACCESS;
		break;
	case ACL_TYPE_DEFAULT:
		name = XATTR_NAME_POSIX_ACL_DEFAULT;
		break;
	default:
		BUG();
	}
	retval = v9fs_fid_xattr_set(fid, name, buffer, size, 0);
err_free_out:
	kfree(buffer);
	return retval;
}

int v9fs_acl_chmod(struct inode *inode, struct p9_fid *fid)
{
	int retval = 0;
	struct posix_acl *acl;

	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;
		set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
		retval = v9fs_set_acl(fid, ACL_TYPE_ACCESS, acl);
		posix_acl_release(acl);
	}
	return retval;
}

int v9fs_set_create_acl(struct inode *inode, struct p9_fid *fid,
			struct posix_acl *dacl, struct posix_acl *acl)
{
	set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
	set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
	v9fs_set_acl(fid, ACL_TYPE_DEFAULT, dacl);
	v9fs_set_acl(fid, ACL_TYPE_ACCESS, acl);
	return 0;
}

void v9fs_put_acl(struct posix_acl *dacl,
		  struct posix_acl *acl)
{
	posix_acl_release(dacl);
	posix_acl_release(acl);
}

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_xattr_get_acl(const struct xattr_handler *handler,
			      struct dentry *dentry, struct inode *inode,
			      const char *name, void *buffer, size_t size)
{
	struct v9fs_session_info *v9ses;
	struct posix_acl *acl;
	int error;

	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_xattr_get(dentry, handler->name, buffer, size);

	acl = v9fs_get_cached_acl(inode, handler->flags);
	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_xattr_set_acl(const struct xattr_handler *handler,
			      struct dentry *dentry, struct inode *inode,
			      const char *name, const void *value,
			      size_t size, int flags)
{
	int retval;
	struct posix_acl *acl;
	struct v9fs_session_info *v9ses;

	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_xattr_set(dentry, handler->name, value, size,
				      flags);

	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(inode->i_sb->s_user_ns, acl);
			if (retval)
				goto err_out;
		}
	} else
		acl = NULL;

	switch (handler->flags) {
	case ACL_TYPE_ACCESS:
		if (acl) {
			struct iattr iattr = { 0 };
			struct posix_acl *old_acl = acl;

			retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);
			if (retval)
				goto err_out;
			if (!acl) {
				/*
				 * ACL can be represented
				 * by the mode bits. So don't
				 * update ACL.
				 */
				posix_acl_release(old_acl);
				value = NULL;
				size = 0;
			}
			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:
		if (!S_ISDIR(inode->i_mode)) {
			retval = acl ? -EINVAL : 0;
			goto err_out;
		}
		break;
	default:
		BUG();
	}
	retval = v9fs_xattr_set(dentry, handler->name, value, size, flags);
	if (!retval)
		set_cached_acl(inode, handler->flags, acl);
err_out:
	posix_acl_release(acl);
	return retval;
}

const struct xattr_handler v9fs_xattr_acl_access_handler = {
	.name	= XATTR_NAME_POSIX_ACL_ACCESS,
	.flags	= ACL_TYPE_ACCESS,
	.get	= v9fs_xattr_get_acl,
	.set	= v9fs_xattr_set_acl,
};

const struct xattr_handler v9fs_xattr_acl_default_handler = {
	.name	= XATTR_NAME_POSIX_ACL_DEFAULT,
	.flags	= ACL_TYPE_DEFAULT,
	.get	= v9fs_xattr_get_acl,
	.set	= v9fs_xattr_set_acl,
};