On Wed, Mar 29, 2023 at 9:05 AM Roberto Sassu
<roberto.sassu@xxxxxxxxxxxxxxx> wrote:
> From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
>
> Reiserfs sets a security xattr at inode creation time in two stages: first,
> it calls reiserfs_security_init() to obtain the xattr from active LSMs;
> then, it calls reiserfs_security_write() to actually write that xattr.
>
> Unfortunately, it seems there is a wrong expectation that LSMs provide the
> full xattr name in the form 'security.<suffix>'. However, LSMs always
> provided just the suffix, causing reiserfs to not write the xattr at all
> (if the suffix is shorter than the prefix), or to write an xattr with the
> wrong name.
>
> Add a temporary buffer in reiserfs_security_write(), and write to it the
> full xattr name, before passing it to reiserfs_xattr_set_handle().
>
> Since the 'security.' prefix is always prepended, remove the name length
> check.
>
> Cc: stable@xxxxxxxxxxxxxxx # v2.6.x
> Fixes: 57fe60df6241 ("reiserfs: add atomic addition of selinux attributes during inode creation")
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> ---
> fs/reiserfs/xattr_security.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/fs/reiserfs/xattr_security.c b/fs/reiserfs/xattr_security.c
> index 6bffdf9a4fd..b0c354ab113 100644
> --- a/fs/reiserfs/xattr_security.c
> +++ b/fs/reiserfs/xattr_security.c
> @@ -95,11 +95,13 @@ int reiserfs_security_write(struct reiserfs_transaction_handle *th,
> struct inode *inode,
> struct reiserfs_security_handle *sec)
> {
> + char xattr_name[XATTR_NAME_MAX + 1];
> int error;
> - if (strlen(sec->name) < sizeof(XATTR_SECURITY_PREFIX))
> - return -EINVAL;
If one really wanted to be paranoid they could verify that
'XATTR_SECURITY_PREFIX_LEN + strlen(sec->name) <= XATTR_NAME_MAX' and
return EINVAL, but that really shouldn't be an issue and if the
concatenation does result in a xattr name that is too big, the
snprintf() will safely truncate/managle it.
Regardless, this patch is fine with me, but it would be nice if at
least of the reiserfs/VFS folks could provide an ACK/Reviewed-by tag,
although I think we can still move forward on this without one of
those.
> - error = reiserfs_xattr_set_handle(th, inode, sec->name, sec->value,
> + snprintf(xattr_name, sizeof(xattr_name), "%s%s", XATTR_SECURITY_PREFIX,
> + sec->name);
> +
> + error = reiserfs_xattr_set_handle(th, inode, xattr_name, sec->value,
> sec->length, XATTR_CREATE);
> if (error == -ENODATA || error == -EOPNOTSUPP)
> error = 0;
> --
> 2.25.1
--
paul-moore.com
