Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA

From: Andy Lutomirski
Date: Wed Sep 30 2015 - 14:47:36 EST

On Wed, Sep 30, 2015 at 11:41 AM, Tycho Andersen
<tycho.andersen@xxxxxxxxxxxxx> wrote:
> On Wed, Sep 30, 2015 at 11:25:41AM -0700, Andy Lutomirski wrote:
>> On Wed, Sep 30, 2015 at 11:13 AM, Tycho Andersen
>> <tycho.andersen@xxxxxxxxxxxxx> wrote:
>> > This command allows comparing the underling private data of two fds. This
>> > is useful e.g. to find out if a seccomp filter is inherited, since struct
>> > seccomp_filter are unique across tasks and are the private_data seccomp
>> > fds.
>> This is very implementation-specific and may have nasty ABI
>> consequences far outside seccomp. Let's do something specific to
>> seccomp and/or eBPF.
> We could change the name to a less generic KCMP_SECCOMP_FD or
> something, but without some sort of GUID on each struct
> seccomp_filter, the implementation would be effectively the same as it
> is today. Is that enough, or do we need a GUID?

I don't care about the GUID. I think we should name it
KCMP_SECCOMP_FD and make it only work on seccomp fds.

Alternatively, we could figure out why KCMP_FILE doesn't do the trick
and consider fixing it. IMO it's really too bad that struct file is
so heavyweight that we can't really just embed one in all kinds of

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