On Thu, Dec 8, 2022 at 4:29 AM Roberto Sassu
<roberto.sassu@xxxxxxxxxxxxxxx> wrote:
> On Wed, 2022-12-07 at 14:34 -0500, Paul Moore wrote:
> > On Wed, Dec 7, 2022 at 4:18 AM Roberto Sassu
> > <roberto.sassu@xxxxxxxxxxxxxxx> wrote:
> > > For this patch, I saw it is already in lsm/next. Paul, should I do an
> > > incremental patch or change the one in the repo and you force push it?
> > > I would just remove the three lines after the parameters description.
> >
> > Just send a patch against the current lsm/next branch to remove those
> > lines, and please do it ASAP as the merge window opens this
> > weekend/Monday.
>
> Ok, was about to send but I would need a clarification first.
>
> In mount_api.rst, there is for security_fs_context_parse_param():
>
> The value pointed to by param may be modified (if a string) or stolen
> (provided the value pointer is NULL'd out). If it is stolen, 0 must be
> returned to prevent it being passed to the filesystem.
>
> Looking at security.c:
>
> hlist_for_each_entry(hp, &security_hook_heads.fs_context_parse_param,
> list) {
> trc = hp->hook.fs_context_parse_param(fc, param);
> if (trc == 0)
> rc = 0;
> else if (trc != -ENOPARAM)
> return trc;
> }
>
> If, as mount_api.rst says, the value is modified by an LSM or stolen,
> should it be passed to other LSMs too?
All of the LSMs should be using fs_parse() in their
fs_context_parse_param() hook to identify the mount options that they
own, skipping those they do not (fs_parse() would return -ENOPARAM in
those cases). I don't believe we currently have any mount options
that are shared across the different LSMs, so I believe this is a
non-issue.
In the future if we ever find the need to share mount options across
different LSMs we will need some additional work to ensure it is
handled properly, but I don't think we need to worry too much about
that now.
--
paul-moore.com
