Messages in this thread | | | From | Aleksandr Mikhalitsyn <> | Date | Thu, 16 Mar 2023 16:32:03 +0100 | Subject | Re: [PATCH net-next 1/3] scm: add SO_PASSPIDFD and SCM_PIDFD |
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On Thu, Mar 16, 2023 at 3:34 PM Eric Dumazet <edumazet@google.com> wrote: > > On Thu, Mar 16, 2023 at 6:16 AM Alexander Mikhalitsyn > <aleksandr.mikhalitsyn@canonical.com> wrote: > > > > Implement SCM_PIDFD, a new type of CMSG type analogical to SCM_CREDENTIALS, > > but it contains pidfd instead of plain pid, which allows programmers not > > to care about PID reuse problem. > > Hi Alexander
Hi Eric
Thanks for the fast reply! ;-)
> > This would add yet another conditional in af_unix fast path. > > It seems that we already can use pidfd_open() (since linux-5.3), and > pass the resulting fd in af_unix SCM_RIGHTS message ?
Yes, it's possible, but it means that from the receiver side we need to trust the sent pidfd (in SCM_RIGHTS), or always use combination of SCM_RIGHTS+SCM_CREDENTIALS, then we can extract pidfd from SCM_RIGHTS, then acquire plain pid from pidfd and after compare it with the pid from SCM_CREDENTIALS.
> > If you think this is not suitable, it should at least be mentioned in > the changelog.
Kind regards, Alex
> > Thanks.
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