On Thu, 2023-03-30 at 17:15 -0400, Paul Moore wrote:
> 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.
Ok, I could do it.
Thanks
Roberto
> 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
