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linux-next/fs/ext4/xattr_security.c
Eryu Guan 3f706c8c92 ext4: use XATTR_CREATE in ext4_initxattrs()
I hit ENOSPC error when creating new file in a newly created ext4
with ea_inode feature enabled, if selinux is enabled and ext4 is
mounted without any selinux context. e.g.

  mkfs -t ext4 -O ea_inode -F /dev/sda5
  mount /dev/sda5 /mnt/ext4
  touch /mnt/ext4/testfile  # got ENOSPC here

It turns out that we run out of journal credits in
ext4_xattr_set_handle() when creating new selinux label for the
newly created inode.

This is because that in __ext4_new_inode() we use
__ext4_xattr_set_credits() to calculate the reserved credits for new
xattr, with the 'is_create' argument being true, which implies less
credits in the ea_inode case. But we calculate the required credits
in ext4_xattr_set_handle() with 'is_create' being false, which means
we need more credits if ea_inode feature is enabled. So we don't
have enough credits and error out with ENOSPC.

Fix it by simply calling ext4_xattr_set_handle() with XATTR_CREATE
flag in ext4_initxattrs(), so we end up with requiring less credits
than reserved. The semantic of XATTR_CREATE is "Perform a pure
create, which fails if the named attribute exists already." (from
setxattr(2)), which is fine in this case, because we only call
ext4_initxattrs() on newly created inode.

Fixes: af65207c76 ("ext4: fix __ext4_new_inode() journal credits calculation")
Cc: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-05-10 11:52:14 -04:00

66 lines
1.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/ext4/xattr_security.c
* Handler for storing security labels as extended attributes.
*/
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/slab.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "xattr.h"
static int
ext4_xattr_security_get(const struct xattr_handler *handler,
struct dentry *unused, struct inode *inode,
const char *name, void *buffer, size_t size)
{
return ext4_xattr_get(inode, EXT4_XATTR_INDEX_SECURITY,
name, buffer, size);
}
static int
ext4_xattr_security_set(const struct xattr_handler *handler,
struct dentry *unused, struct inode *inode,
const char *name, const void *value,
size_t size, int flags)
{
return ext4_xattr_set(inode, EXT4_XATTR_INDEX_SECURITY,
name, value, size, flags);
}
static int
ext4_initxattrs(struct inode *inode, const struct xattr *xattr_array,
void *fs_info)
{
const struct xattr *xattr;
handle_t *handle = fs_info;
int err = 0;
for (xattr = xattr_array; xattr->name != NULL; xattr++) {
err = ext4_xattr_set_handle(handle, inode,
EXT4_XATTR_INDEX_SECURITY,
xattr->name, xattr->value,
xattr->value_len, XATTR_CREATE);
if (err < 0)
break;
}
return err;
}
int
ext4_init_security(handle_t *handle, struct inode *inode, struct inode *dir,
const struct qstr *qstr)
{
return security_inode_init_security(inode, dir, qstr,
&ext4_initxattrs, handle);
}
const struct xattr_handler ext4_xattr_security_handler = {
.prefix = XATTR_SECURITY_PREFIX,
.get = ext4_xattr_security_get,
.set = ext4_xattr_security_set,
};