Messages in this thread | | | From | (Eric W. Biederman) | Date | Thu, 04 Apr 2013 03:22:07 -0700 | Subject | Re: [PATCH 1/2] Revert "af_unix: dont send SCM_CREDENTIAL when dest socket is NULL" |
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dingtianhong <dingtianhong@huawei.com> writes:
> On 2013/4/4 10:13, Eric W. Biederman wrote: >> >> This reverts commit 14134f6584212d585b310ce95428014b653dfaf6. >> >> The problem that the above patch was meant to address is that af_unix >> messages are not being coallesced because we are sending unnecesarry >> credentials. Not sending credentials in maybe_add_creds totally >> breaks unconnected unix domain sockets that wish to send credentails >> to other sockets. >> > > thanks for check the question and make a fix solution, but I still doubt that if unconnected unix > domain socket wish to send credentails to oher sockets, why dont set > SOCK_PASSCRED on sock->flags, I think the user need to decide the param > and shouldnt send creds by default way.
The big issue is the semantics are the receiver sets SOCK_PASSCRED when they want to receive credentials. When transmitting packets from unconnected or unaccepted sockets we don't know if the receiver has set SOCK_PASSCRED so when in doubt transmit. Historically we always tranmitted credentials.
Furthermore we have a real regression in udev that breaks systems, so this patch must be reverted.
Eric
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