Messages in this thread | | | From | Aleksandr Mikhalitsyn <> | Date | Mon, 27 Feb 2023 11:21:13 +0100 | Subject | Re: [PATCH net-next] scm: fix MSG_CTRUNC setting condition for SO_PASSSEC |
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On Mon, Feb 27, 2023 at 11:01 AM Eric Dumazet <edumazet@google.com> wrote: > > On Sun, Feb 26, 2023 at 9:17 PM Alexander Mikhalitsyn > <aleksandr.mikhalitsyn@canonical.com> wrote: > > > > Currently, we set MSG_CTRUNC flag is we have no > > msg_control buffer provided and SO_PASSCRED is set > > or if we have pending SCM_RIGHTS. > > > > For some reason we have no corresponding check for > > SO_PASSSEC. >
Hi Eric,
> Can you describe what side effects this patch has ? > > I think it could break some applications, who might not be able to > recover from MSG_CTRUNC in this case. > This should be documented, in order to avoid a future revert.
Yes, it can break applications but only those who use SO_PASSSEC and not properly check MSG_CTRUNC. According to the recv(2) man:
MSG_CTRUNC indicates that some control data was discarded due to lack of space in the buffer for ancillary data.
So, there is no specification about a particular SCM type. It seems more correct to handle SCM_SECURITY the same way as SCM_RIGHTS / SCM_CREDENTIALS.
> > In any case, net-next is currently closed.
Oh, I'm sorry.
Kind regards, Alex
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