Re: [PATCH v6 bpf-next 3/4] bpf: add bpf_init_inode_xattr kfunc for atomic inode labeling

On Sat Aug 1, 2026 at 1:11 AM CEST, David Windsor wrote:
> On Fri, Jul 31, 2026 at 6:23 PM Paul Moore <[email protected]> wrote:
>>
>> On Fri, Jul 31, 2026 at 6:04 PM Kumar Kartikeya Dwivedi
>> <[email protected]> wrote:
>> > On Fri Jul 31, 2026 at 11:49 PM CEST, Paul Moore wrote:
>> > > On Fri, Jul 31, 2026 at 5:29 PM Kumar Kartikeya Dwivedi
>> > > <[email protected]> wrote:
>> > >> On Fri Jul 31, 2026 at 10:48 PM CEST, Paul Moore wrote:
>> > >> > On Fri, Jul 31, 2026 at 4:16 PM Kumar Kartikeya Dwivedi
>> > >> > <[email protected]> wrote:
>> > >> >> On Fri Jul 31, 2026 at 10:01 PM CEST, Paul Moore wrote:
>> > >> >> > On Fri, Jul 31, 2026 at 3:20 PM Kumar Kartikeya Dwivedi
>> > >> >> > <[email protected]> wrote:
>> > >> >> >> On Fri Jul 31, 2026 at 9:05 PM CEST, Paul Moore wrote:
>> > >> >> >> > On Fri, Jul 31, 2026 at 2:50 PM Kumar Kartikeya Dwivedi
>> > >> >> >> > <[email protected]> wrote:
>> > >> >> >> >> On Fri Jul 31, 2026 at 8:42 PM CEST, Paul Moore wrote:
>> > >> >> >> >> > On Fri, Jul 31, 2026 at 2:18 PM Kumar Kartikeya Dwivedi
>> > >> >> >> >> > <[email protected]> wrote:
>> > >> >> >> >> >> On Fri Jul 31, 2026 at 6:59 PM CEST, Paul Moore wrote:
>> > >> >> >> >> >> > On Fri, Jul 31, 2026 at 12:32 PM Kumar Kartikeya Dwivedi
>> > >> >> >> >> >> > <[email protected]> wrote:
>> > >> >> >> >> >> >> On Fri Jul 31, 2026 at 6:02 PM CEST, Paul Moore wrote:
>> > >> >> >> >> >> >> > On Fri, Jul 31, 2026 at 11:44 AM Kumar Kartikeya Dwivedi
>> > >> >> >> >> >> >> > <[email protected]> wrote:
>> > >> >> >> >> >> >> >> On Fri Jul 31, 2026 at 5:30 PM CEST, David Windsor wrote:
>> > >> >> >> >> >> >> >> > On Fri, Jul 31, 2026 at 11:17 AM Paul Moore <[email protected]> wrote:
>>
>> ...
>>
>> > As a consequence, everyone suffers because they first need to satisfy your whims
>> > on how all code and kfuncs written thus far are wrong, and need to be moved
>> > around ASAP, including the one being proposed.
>>
>> That's not a reasonble or truthful summary of things, I've only
>> requested that David locate his proposed kfunc in
>> security/bpf_lsm_kfuncs.c, I never suggested he move any others.
>>
>
> Looking at what's left of the kfunc itself, it's basically nothing.
> Everything meaningful has been moved into security/ already.
>
> Aside from bpf dynptr ops, what's left is:
>
> if (!name__str)
>     return -EINVAL;
>

You can actually lose this one, the verifier should prevent passing NULL for
name__str. Other functions don't check it either. Feel free to check it, or add
a negative test in case you're worried about it.

> if (strncmp(name__str, XATTR_BPF_LSM_SUFFIX, sizeof(XATTR_BPF_LSM_SUFFIX) - 1))
>     return -EPERM;
>
> if (!xattrs->xattrs)
>     return -EOPNOTSUPP;
>
> ... then a call to security_lsmxattr_add. Why not move this chunk into
> security_lsmxattr_add, and leave the remaining bits, which are pure
> bpf, in fs/ for now, and litigate the total placement of all of them
> once v7 lands?
>

I wouldn't bother, everything LSM specific is already where it belongs.  That
said, your question is a good demonstration of the absurdity of the ask here.

>> --
>> paul-moore.com