freebsd-dev/module/zfs/zpl_xattr.c

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/*
* 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
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* 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.
*
* Extended attributes (xattr) on Solaris are implemented as files
* which exist in a hidden xattr directory. These extended attributes
* can be accessed using the attropen() system call which opens
* the extended attribute. It can then be manipulated just like
* a standard file descriptor. This has a couple advantages such
* as practically no size limit on the file, and the extended
* attributes permissions may differ from those of the parent file.
* This interface is really quite clever, but it's also completely
* different than what is supported on Linux.
*
* Under Linux extended attributes are manipulated by the system
* calls getxattr(2), setxattr(2), and listxattr(2). They consider
* extended attributes to be name/value pairs where the name is a
* NULL terminated string. The name must also include one of the
* following name space prefixes:
*
* user - No restrictions and is available to user applications.
* trusted - Restricted to kernel and root (CAP_SYS_ADMIN) use.
* system - Used for access control lists (system.nfs4_acl, etc).
* security - Used by SELinux to store a files security context.
*
* This Linux interface is implemented internally using the more
* flexible Solaris style extended attributes. Every extended
* attribute is store as a file in a hidden directory associated
* with the parent file. This ensures on disk compatibility with
* zfs implementations on other platforms (Solaris, FreeBSD, MacOS).
*
* One consequence of this implementation is that when an extended
* attribute is manipulated an inode is created. This inode will
* exist in the Linux inode cache but there will be no associated
* entry in the dentry cache which references it. This is safe
* but it may result in some confusion.
*
* Longer term I would like to see the 'security.selinux' extended
* attribute moved to a SA. This should significantly improve
* performance on a SELinux enabled system by minimizing the
* number of seeks required to access a file. However, for now
* this xattr is still stored in a file because I'm pretty sure
* adding a new SA will break on-disk compatibility.
*/
#include <sys/zfs_vfsops.h>
#include <sys/zfs_vnops.h>
#include <sys/zfs_znode.h>
#include <sys/vfs.h>
#include <sys/zpl.h>
typedef struct xattr_filldir {
size_t size;
size_t offset;
char *buf;
struct inode *inode;
} xattr_filldir_t;
static int
zpl_xattr_filldir(void *arg, const char *name, int name_len,
loff_t offset, uint64_t objnum, unsigned int d_type)
{
xattr_filldir_t *xf = arg;
if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
if (!(ITOZSB(xf->inode)->z_flags & ZSB_XATTR_USER))
return (0);
if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
if (!capable(CAP_SYS_ADMIN))
return (0);
/* When xf->buf is NULL only calculate the required size. */
if (xf->buf) {
if (xf->offset + name_len + 1 > xf->size)
return (-ERANGE);
memcpy(xf->buf + xf->offset, name, name_len);
xf->buf[xf->offset + name_len] = '\0';
}
xf->offset += (name_len + 1);
return (0);
}
ssize_t
zpl_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
{
struct inode *ip = dentry->d_inode;
struct inode *dxip = NULL;
loff_t pos = 3; /* skip '.', '..', and '.zfs' entries. */
cred_t *cr;
int error;
xattr_filldir_t xf = { buffer_size, 0, buffer, ip };
cr = (cred_t *)get_current_cred();
/* Lookup the xattr directory */
error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR, cr, NULL, NULL);
if (error) {
if (error == -ENOENT)
error = 0;
goto out;
}
/* Fill provided buffer via zpl_zattr_filldir helper */
error = -zfs_readdir(dxip, (void *)&xf, zpl_xattr_filldir, &pos, cr);
if (error)
goto out;
error = xf.offset;
out:
if (dxip)
iput(dxip);
put_cred(cr);
return (error);
}
static int
zpl_xattr_get(struct inode *ip, const char *name, void *buf, size_t size)
{
struct inode *dxip = NULL;
struct inode *xip = NULL;
cred_t *cr;
int error;
cr = (cred_t *)get_current_cred();
/* Lookup the xattr directory */
error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR, cr, NULL, NULL);
if (error)
goto out;
/* Lookup a specific xattr name in the directory */
error = -zfs_lookup(dxip, (char *)name, &xip, 0, cr, NULL, NULL);
if (error)
goto out;
if (!size) {
error = i_size_read(xip);
goto out;
}
error = zpl_read_common(xip, buf, size, 0, UIO_SYSSPACE, 0, cr);
out:
if (xip)
iput(xip);
if (dxip)
iput(dxip);
put_cred(cr);
if (error == -ENOENT)
error = -ENODATA;
return (error);
}
static int
zpl_xattr_set(struct inode *ip, const char *name, const void *value,
size_t size, int flags)
{
struct inode *dxip = NULL;
struct inode *xip = NULL;
vattr_t *vap = NULL;
cred_t *cr;
ssize_t wrote;
int error;
cr = (cred_t *)get_current_cred();
/* Lookup the xattr directory and create it if required. */
error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR | CREATE_XATTR_DIR,
cr, NULL, NULL);
if (error)
goto out;
/*
* Lookup a specific xattr name in the directory, two failure modes:
* XATTR_CREATE: fail if xattr already exists
* XATTR_REMOVE: fail if xattr does not exist
*/
error = -zfs_lookup(dxip, (char *)name, &xip, 0, cr, NULL, NULL);
if (error) {
if (error != -ENOENT)
goto out;
if ((error == -ENOENT) && (flags & XATTR_REPLACE))
goto out;
} else {
error = -EEXIST;
if (flags & XATTR_CREATE)
goto out;
}
error = 0;
/* Remove a specific name xattr when value is set to NULL. */
if (value == NULL) {
if (xip)
error = -zfs_remove(dxip, (char *)name, cr);
goto out;
}
/* Lookup failed create a new xattr. */
if (xip == NULL) {
vap = kmem_zalloc(sizeof(vattr_t), KM_SLEEP);
vap->va_mode = S_IFREG | 0644;
vap->va_mask = ATTR_MODE;
vap->va_uid = current_fsuid();
vap->va_gid = current_fsgid();
error = -zfs_create(dxip, (char *)name, vap, 0, 0644, &xip,
cr, 0, NULL);
if (error)
goto out;
}
ASSERT(xip != NULL);
wrote = zpl_write_common(xip, value, size, 0, UIO_SYSSPACE, 0, cr);
if (wrote < 0)
error = wrote;
out:
if (vap)
kmem_free(vap, sizeof(vattr_t));
if (xip)
iput(xip);
if (dxip)
iput(dxip);
put_cred(cr);
if (error == -ENOENT)
error = -ENODATA;
ASSERT3S(error, <=, 0);
return (error);
}
static int
__zpl_xattr_user_get(struct inode *ip, const char *name,
void *buffer, size_t size)
{
char *xattr_name;
int error;
if (strcmp(name, "") == 0)
return -EINVAL;
if (!(ITOZSB(ip)->z_flags & ZSB_XATTR_USER))
return -EOPNOTSUPP;
xattr_name = kmem_asprintf("%s%s", XATTR_USER_PREFIX, name);
error = zpl_xattr_get(ip, xattr_name, buffer, size);
strfree(xattr_name);
return (error);
}
ZPL_XATTR_GET_WRAPPER(zpl_xattr_user_get);
static int
__zpl_xattr_user_set(struct inode *ip, const char *name,
const void *value, size_t size, int flags)
{
char *xattr_name;
int error;
if (strcmp(name, "") == 0)
return -EINVAL;
if (!(ITOZSB(ip)->z_flags & ZSB_XATTR_USER))
return -EOPNOTSUPP;
xattr_name = kmem_asprintf("%s%s", XATTR_USER_PREFIX, name);
error = zpl_xattr_set(ip, xattr_name, value, size, flags);
strfree(xattr_name);
return (error);
}
ZPL_XATTR_SET_WRAPPER(zpl_xattr_user_set);
xattr_handler_t zpl_xattr_user_handler = {
.prefix = XATTR_USER_PREFIX,
.get = zpl_xattr_user_get,
.set = zpl_xattr_user_set,
};
static int
__zpl_xattr_trusted_get(struct inode *ip, const char *name,
void *buffer, size_t size)
{
char *xattr_name;
int error;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
if (strcmp(name, "") == 0)
return -EINVAL;
xattr_name = kmem_asprintf("%s%s", XATTR_TRUSTED_PREFIX, name);
error = zpl_xattr_get(ip, xattr_name, buffer, size);
strfree(xattr_name);
return (error);
}
ZPL_XATTR_GET_WRAPPER(zpl_xattr_trusted_get);
static int
__zpl_xattr_trusted_set(struct inode *ip, const char *name,
const void *value, size_t size, int flags)
{
char *xattr_name;
int error;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
if (strcmp(name, "") == 0)
return -EINVAL;
xattr_name = kmem_asprintf("%s%s", XATTR_TRUSTED_PREFIX, name);
error = zpl_xattr_set(ip, xattr_name, value, size, flags);
strfree(xattr_name);
return (error);
}
ZPL_XATTR_SET_WRAPPER(zpl_xattr_trusted_set);
xattr_handler_t zpl_xattr_trusted_handler = {
.prefix = XATTR_TRUSTED_PREFIX,
.get = zpl_xattr_trusted_get,
.set = zpl_xattr_trusted_set,
};
static int
__zpl_xattr_security_get(struct inode *ip, const char *name,
void *buffer, size_t size)
{
char *xattr_name;
int error;
if (strcmp(name, "") == 0)
return -EINVAL;
xattr_name = kmem_asprintf("%s%s", XATTR_SECURITY_PREFIX, name);
error = zpl_xattr_get(ip, xattr_name, buffer, size);
strfree(xattr_name);
return (error);
}
ZPL_XATTR_GET_WRAPPER(zpl_xattr_security_get);
static int
__zpl_xattr_security_set(struct inode *ip, const char *name,
const void *value, size_t size, int flags)
{
char *xattr_name;
int error;
if (strcmp(name, "") == 0)
return -EINVAL;
xattr_name = kmem_asprintf("%s%s", XATTR_SECURITY_PREFIX, name);
error = zpl_xattr_set(ip, xattr_name, value, size, flags);
strfree(xattr_name);
return (error);
}
ZPL_XATTR_SET_WRAPPER(zpl_xattr_security_set);
int
zpl_xattr_security_init(struct inode *ip, struct inode *dip)
{
int error;
size_t len;
void *value;
char *name;
error = security_inode_init_security(ip, dip, &name, &value, &len);
if (error) {
if (error == -EOPNOTSUPP)
return 0;
return (error);
}
error = __zpl_xattr_security_set(ip, name, value, len, 0);
kfree(name);
kfree(value);
return (error);
}
xattr_handler_t zpl_xattr_security_handler = {
.prefix = XATTR_SECURITY_PREFIX,
.get = zpl_xattr_security_get,
.set = zpl_xattr_security_set,
};
xattr_handler_t *zpl_xattr_handlers[] = {
&zpl_xattr_security_handler,
&zpl_xattr_trusted_handler,
&zpl_xattr_user_handler,
#ifdef HAVE_POSIX_ACLS
&zpl_xattr_acl_access_handler,
&zpl_xattr_acl_default_handler,
#endif /* HAVE_POSIX_ACLS */
};