On Thu, Dec 8, 2022 at 4:29 AM Roberto Sassu
[off-list ref] wrote:

On Wed, 2022-12-07 at 14:34 -0500, Paul Moore wrote:

quoted

On Wed, Dec 7, 2022 at 4:18 AM Roberto Sassu
[off-list ref] wrote:

quoted

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