![Artem Savkov](/assets/img/avatar_default.png)
Commit 2a6fba6
"xfs: only return -errno or success from attr ->put_listent"
changes the returnvalue of __xfs_xattr_put_listen to 0 in case when there is
insufficient space in the buffer assuming that setting context->count to -1
would be enough, but all of the ->put_listent callers only check seen_enough.
This results in a failed assertion:
XFS: Assertion failed: context->count >= 0, file: fs/xfs/xfs_xattr.c, line: 175
in insufficient buffer size case.
This is only reproducible with at least 2 xattrs and only when the buffer
gets depleted before the last one.
Furthermore if buffersize is such that it is enough to hold the last xattr's
name, but not enough to hold the sum of preceeding xattr names listxattr won't
fail with ERANGE, but will suceed returning last xattr's name without the
first character. The first character end's up overwriting data stored at
(context->alist - 1).
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
255 lines
6.1 KiB
C
255 lines
6.1 KiB
C
/*
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* Copyright (C) 2008 Christoph Hellwig.
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* Portions Copyright (C) 2000-2008 Silicon Graphics, Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "xfs.h"
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#include "xfs_format.h"
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#include "xfs_log_format.h"
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#include "xfs_trans_resv.h"
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#include "xfs_mount.h"
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#include "xfs_da_format.h"
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#include "xfs_inode.h"
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#include "xfs_attr.h"
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#include "xfs_attr_leaf.h"
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#include "xfs_acl.h"
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#include <linux/posix_acl_xattr.h>
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#include <linux/xattr.h>
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static int
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xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused,
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struct inode *inode, const char *name, void *value, size_t size)
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{
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int xflags = handler->flags;
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struct xfs_inode *ip = XFS_I(inode);
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int error, asize = size;
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/* Convert Linux syscall to XFS internal ATTR flags */
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if (!size) {
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xflags |= ATTR_KERNOVAL;
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value = NULL;
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}
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error = xfs_attr_get(ip, (unsigned char *)name, value, &asize, xflags);
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if (error)
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return error;
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return asize;
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}
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void
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xfs_forget_acl(
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struct inode *inode,
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const char *name,
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int xflags)
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{
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/*
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* Invalidate any cached ACLs if the user has bypassed the ACL
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* interface. We don't validate the content whatsoever so it is caller
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* responsibility to provide data in valid format and ensure i_mode is
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* consistent.
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*/
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if (xflags & ATTR_ROOT) {
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#ifdef CONFIG_XFS_POSIX_ACL
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if (!strcmp(name, SGI_ACL_FILE))
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forget_cached_acl(inode, ACL_TYPE_ACCESS);
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else if (!strcmp(name, SGI_ACL_DEFAULT))
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forget_cached_acl(inode, ACL_TYPE_DEFAULT);
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#endif
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}
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}
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static int
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xfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused,
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struct inode *inode, const char *name, const void *value,
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size_t size, int flags)
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{
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int xflags = handler->flags;
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struct xfs_inode *ip = XFS_I(inode);
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int error;
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/* Convert Linux syscall to XFS internal ATTR flags */
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if (flags & XATTR_CREATE)
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xflags |= ATTR_CREATE;
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if (flags & XATTR_REPLACE)
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xflags |= ATTR_REPLACE;
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if (!value)
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return xfs_attr_remove(ip, (unsigned char *)name, xflags);
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error = xfs_attr_set(ip, (unsigned char *)name,
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(void *)value, size, xflags);
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if (!error)
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xfs_forget_acl(inode, name, xflags);
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return error;
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}
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static const struct xattr_handler xfs_xattr_user_handler = {
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.prefix = XATTR_USER_PREFIX,
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.flags = 0, /* no flags implies user namespace */
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.get = xfs_xattr_get,
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.set = xfs_xattr_set,
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};
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static const struct xattr_handler xfs_xattr_trusted_handler = {
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.prefix = XATTR_TRUSTED_PREFIX,
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.flags = ATTR_ROOT,
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.get = xfs_xattr_get,
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.set = xfs_xattr_set,
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};
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static const struct xattr_handler xfs_xattr_security_handler = {
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.prefix = XATTR_SECURITY_PREFIX,
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.flags = ATTR_SECURE,
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.get = xfs_xattr_get,
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.set = xfs_xattr_set,
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};
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const struct xattr_handler *xfs_xattr_handlers[] = {
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&xfs_xattr_user_handler,
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&xfs_xattr_trusted_handler,
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&xfs_xattr_security_handler,
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#ifdef CONFIG_XFS_POSIX_ACL
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&posix_acl_access_xattr_handler,
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&posix_acl_default_xattr_handler,
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#endif
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NULL
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};
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static int
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__xfs_xattr_put_listent(
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struct xfs_attr_list_context *context,
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char *prefix,
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int prefix_len,
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unsigned char *name,
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int namelen)
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{
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char *offset;
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int arraytop;
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if (!context->alist)
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goto compute_size;
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arraytop = context->count + prefix_len + namelen + 1;
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if (arraytop > context->firstu) {
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context->count = -1; /* insufficient space */
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context->seen_enough = 1;
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return 0;
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}
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offset = (char *)context->alist + context->count;
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strncpy(offset, prefix, prefix_len);
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offset += prefix_len;
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strncpy(offset, (char *)name, namelen); /* real name */
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offset += namelen;
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*offset = '\0';
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compute_size:
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context->count += prefix_len + namelen + 1;
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return 0;
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}
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static int
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xfs_xattr_put_listent(
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struct xfs_attr_list_context *context,
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int flags,
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unsigned char *name,
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int namelen,
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int valuelen)
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{
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char *prefix;
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int prefix_len;
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ASSERT(context->count >= 0);
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if (flags & XFS_ATTR_ROOT) {
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#ifdef CONFIG_XFS_POSIX_ACL
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if (namelen == SGI_ACL_FILE_SIZE &&
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strncmp(name, SGI_ACL_FILE,
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SGI_ACL_FILE_SIZE) == 0) {
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int ret = __xfs_xattr_put_listent(
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context, XATTR_SYSTEM_PREFIX,
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XATTR_SYSTEM_PREFIX_LEN,
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XATTR_POSIX_ACL_ACCESS,
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strlen(XATTR_POSIX_ACL_ACCESS));
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if (ret)
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return ret;
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} else if (namelen == SGI_ACL_DEFAULT_SIZE &&
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strncmp(name, SGI_ACL_DEFAULT,
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SGI_ACL_DEFAULT_SIZE) == 0) {
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int ret = __xfs_xattr_put_listent(
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context, XATTR_SYSTEM_PREFIX,
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XATTR_SYSTEM_PREFIX_LEN,
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XATTR_POSIX_ACL_DEFAULT,
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strlen(XATTR_POSIX_ACL_DEFAULT));
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if (ret)
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return ret;
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}
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#endif
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/*
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* Only show root namespace entries if we are actually allowed to
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* see them.
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*/
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if (!capable(CAP_SYS_ADMIN))
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return 0;
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prefix = XATTR_TRUSTED_PREFIX;
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prefix_len = XATTR_TRUSTED_PREFIX_LEN;
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} else if (flags & XFS_ATTR_SECURE) {
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prefix = XATTR_SECURITY_PREFIX;
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prefix_len = XATTR_SECURITY_PREFIX_LEN;
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} else {
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prefix = XATTR_USER_PREFIX;
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prefix_len = XATTR_USER_PREFIX_LEN;
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}
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return __xfs_xattr_put_listent(context, prefix, prefix_len, name,
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namelen);
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}
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ssize_t
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xfs_vn_listxattr(
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struct dentry *dentry,
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char *data,
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size_t size)
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{
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struct xfs_attr_list_context context;
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struct attrlist_cursor_kern cursor = { 0 };
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struct inode *inode = d_inode(dentry);
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int error;
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/*
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* First read the regular on-disk attributes.
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*/
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memset(&context, 0, sizeof(context));
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context.dp = XFS_I(inode);
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context.cursor = &cursor;
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context.resynch = 1;
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context.alist = size ? data : NULL;
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context.bufsize = size;
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context.firstu = context.bufsize;
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context.put_listent = xfs_xattr_put_listent;
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error = xfs_attr_list_int(&context);
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if (error)
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return error;
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if (context.count < 0)
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return -ERANGE;
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return context.count;
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}
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