Re: [PATCH] net/xfrm: Fix lookups for states with spi == 0

[Herbert Xu]

On Wed, May 02, 2018 at 03:02:20AM +0100, Dmitry Safonov wrote:
> It seems to be a valid use case to add xfrm state without
> Security Parameter Indexes (SPI) value associated:
> ip xfrm state add src $src dst $dst proto $proto mode $mode sel src $src dst $dst $algo
> 
> The bad thing is that it's currently impossible to get/delete the state
> without SPI: __xfrm_state_insert() obviously doesn't add hash for zero
> SPI in xfrm.state_byspi, and xfrm_user_state_lookup() will fail as
> xfrm_state_lookup() does lookups by hash.
> 
> It also isn't possible to workaround from userspace as
> xfrm_id_proto_match() will be always true for ah/esp/comp protos.
> 
> So, don't try looking up by hash if SPI == 0.
> 
> Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx
> Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>

A zero SPI is illegal for many IPsec protocols because that value
is used for other purposes, e.g., IKE encapsulation.

Cheers,
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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