[openib-general] multicast code/merge status

[Michael S. Tsirkin]

> Quoting Sean Hefty <mshefty at ichips.intel.com>:
> Subject: Re: multicast code/merge status
> 
> > sure, it can use the rdmacm qkey (0x1234567 etc) when it creates the QP 
> > and later --if-- the user joins a multicast group modify the qp state 
> > with the group qkey and report it in the cma event such that the 
> > consumer of the rdmacm would set this into his IB UD TX WR
> 
> Changing the qkey would break its existing UD communication.
> 
> > Bottom line, Looking in the IB SPEC and IPoIB RFC i did not see 
> > mentioning of privileged QKEY.
> 
>  From RFC 4391 (ipoib RFC), 4.1:
> 
>   2. Q_Key
> 
>            It is RECOMMENDED that a controlled Q_Key be used with the
>            high-order bit set.  This is to prevent non-privileged
>            software from fabricating and sending out bogus IP datagrams.

BTW, should we be worried that proposed extension (passing qkey in rdma cm param
list) seems to expose this qkey to non-privileged software?
Maybe a machanism should be in place to control access to this separately
from regular rdma cm for RC QPs?


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MST