linux-kernel - Re: [PATCH ipsec v6] xfrm: replay: Fix ESN wrap around for GSO

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Message-ID: <Y0aI2bGb24M5vA7B@gondor.apana.org.au>
Date:   Wed, 12 Oct 2022 17:28:57 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Christian Langrock <christian.langrock@...unet.com>
Cc:     Steffen Klassert <steffen.klassert@...unet.com>,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH ipsec v6] xfrm: replay: Fix ESN wrap around for GSO

On Fri, Oct 07, 2022 at 04:50:15PM +0200, Christian Langrock wrote:
> When using GSO it can happen that the wrong seq_hi is used for the last
> packets before the wrap around. This can lead to double usage of a
> sequence number. To avoid this, we should serialize this last GSO
> packet.
> 
> Fixes: d7dbefc45cf5 ("xfrm: Add xfrm_replay_overflow functions for offloading")
> Co-developed-by: Steffen Klassert <steffen.klassert@...unet.com>
> Signed-off-by: Christian Langrock <christian.langrock@...unet.com>
> ---
> Changes in v6:
>  - move overflow check to offloading path to avoid locking issues
> 
> Changes in v5:
>  - Fix build
> 
> Changes in v4:
>  - move changelog within comment
>  - add reviewer
> 
> Changes in v3:
> - fix build
> - remove wrapper function
> 
> Changes in v2:
> - switch to bool as return value
> - remove switch case in wrapper function
> ---
>  net/ipv4/esp4_offload.c |  3 +++
>  net/ipv6/esp6_offload.c |  3 +++
>  net/xfrm/xfrm_device.c  | 15 ++++++++++++++-
>  net/xfrm/xfrm_replay.c  |  2 +-
>  4 files changed, 21 insertions(+), 2 deletions(-)

Could you please explain how this code restructure makes it safe
with respect to multiple users of the same xfrm_state?

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt