Commit d9a73859 authored by Jim Garlick's avatar Jim Garlick Committed by Eric Van Hensbergen
Browse files

fs/9p: xattr: add trusted and security namespaces 

Allow requests for security.* and trusted.* xattr name spaces
to pass through to server.

The new files are 99% cut and paste from fs/9p/xattr_user.c with the
namespaces changed.  It has the intended effect in superficial testing.
I do not know much detail about how these namespaces are used, but passing
them through to the server, which can decide whether to handle them or not,
seems reasonable.

I want to support a use case where an ext4 file system is mounted via 9P,
then re-exported via samba to windows clients in a cluster.  Windows wants
to store xattrs such as security.NTACL.  This works when ext4 directly
backs samba, but not when 9P is inserted.  This use case is documented here:
   http://code.google.com/p/diod/issues/detail?id=95



Signed-off-by: default avatarJim Garlick <garlick@llnl.gov>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent 2f28c8b3

fs/9p/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -31,3 +31,16 @@ config 9P_FS_POSIX_ACL 
	  If you don't know what Access Control Lists are, say N



endif





config 9P_FS_SECURITY

        bool "9P Security Labels"

        depends on 9P_FS

        help

          Security labels support alternative access control models

          implemented by security modules like SELinux.  This option

          enables an extended attribute handler for file security

          labels in the 9P filesystem.



          If you are not using a security module that requires using

          extended attributes for file security labels, say N.

fs/9p/Makefile

+3 −1
Original line number Diff line number Diff line
@@ -11,7 +11,9 @@ obj-$(CONFIG_9P_FS) := 9p.o 
	v9fs.o \

	fid.o  \

	xattr.o \

	xattr_user.o

	xattr_user.o \

	xattr_trusted.o



9p-$(CONFIG_9P_FSCACHE) += cache.o

9p-$(CONFIG_9P_FS_POSIX_ACL) += acl.o

9p-$(CONFIG_9P_FS_SECURITY) += xattr_security.o

fs/9p/xattr.c

+4 −0
Original line number Diff line number Diff line
@@ -167,9 +167,13 @@ ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) 


const struct xattr_handler *v9fs_xattr_handlers[] = {

	&v9fs_xattr_user_handler,

	&v9fs_xattr_trusted_handler,

#ifdef CONFIG_9P_FS_POSIX_ACL

	&v9fs_xattr_acl_access_handler,

	&v9fs_xattr_acl_default_handler,

#endif

#ifdef CONFIG_9P_FS_SECURITY

	&v9fs_xattr_security_handler,

#endif

	NULL

};

fs/9p/xattr.h

+2 −0
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ 


extern const struct xattr_handler *v9fs_xattr_handlers[];

extern struct xattr_handler v9fs_xattr_user_handler;

extern struct xattr_handler v9fs_xattr_trusted_handler;

extern struct xattr_handler v9fs_xattr_security_handler;

extern const struct xattr_handler v9fs_xattr_acl_access_handler;

extern const struct xattr_handler v9fs_xattr_acl_default_handler;

fs/9p/xattr_security.c

0 → 100644
+80 −0
Original line number Diff line number Diff line 
/*

 * 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/string.h>

#include <linux/fs.h>

#include <linux/slab.h>

#include "xattr.h"



static int v9fs_xattr_security_get(struct dentry *dentry, const char *name,

			void *buffer, size_t size, int type)

{

	int retval;

	char *full_name;

	size_t name_len;

	size_t prefix_len = XATTR_SECURITY_PREFIX_LEN;



	if (name == NULL)

		return -EINVAL;



	if (strcmp(name, "") == 0)

		return -EINVAL;



	name_len = strlen(name);

	full_name = kmalloc(prefix_len + name_len + 1 , GFP_KERNEL);

	if (!full_name)

		return -ENOMEM;

	memcpy(full_name, XATTR_SECURITY_PREFIX, prefix_len);

	memcpy(full_name+prefix_len, name, name_len);

	full_name[prefix_len + name_len] = '\0';



	retval = v9fs_xattr_get(dentry, full_name, buffer, size);

	kfree(full_name);

	return retval;

}



static int v9fs_xattr_security_set(struct dentry *dentry, const char *name,

			const void *value, size_t size, int flags, int type)

{

	int retval;

	char *full_name;

	size_t name_len;

	size_t prefix_len = XATTR_SECURITY_PREFIX_LEN;



	if (name == NULL)

		return -EINVAL;



	if (strcmp(name, "") == 0)

		return -EINVAL;



	name_len = strlen(name);

	full_name = kmalloc(prefix_len + name_len + 1 , GFP_KERNEL);

	if (!full_name)

		return -ENOMEM;

	memcpy(full_name, XATTR_SECURITY_PREFIX, prefix_len);

	memcpy(full_name + prefix_len, name, name_len);

	full_name[prefix_len + name_len] = '\0';



	retval = v9fs_xattr_set(dentry, full_name, value, size, flags);

	kfree(full_name);

	return retval;

}



struct xattr_handler v9fs_xattr_security_handler = {

	.prefix	= XATTR_SECURITY_PREFIX,

	.get	= v9fs_xattr_security_get,

	.set	= v9fs_xattr_security_set,

};

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