netdev - Re: IPSec ESN: Packets decryption fail with ESN enabled connection

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Date:   Wed, 26 Dec 2018 15:16:29 +0530
From:   Harsh Jain <harsh@...lsio.com>
To:     steffen.klassert@...unet.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, netdev@...r.kernel.org,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Cc:     atul.gupta@...lsio.com, harshjain.prof@...il.com
Subject: Re: IPSec ESN: Packets decryption fail with ESN enabled connection

+linux-crypto

On 26-12-2018 14:54, Harsh Jain wrote:
> Hi All,
>
> Kernel version on both machines: 4.19.7.
>
> Packet drops with EBADMSG is observed on receive end of connection. It seems that sometimes crypto driver receives packet with wrong "seq_hi" value in AAD. See below the dump of assoc data for 1 such instance.
>
> [  380.823454] assoclen 8th byte 1 clen 1464 op 1  ==> High byte of ESN
> [  380.828398] authsize 12 cryptlen 1464
> [  380.832637] dt00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 06 ==> Decrypted data seems correct,last byte is proto(06 TCP)
> [  380.840215] dt00000010: bf ee 4f 80 a4 7f 2a 50 6a 5a 0b 10
> [  380.846636] ass00000000: 0a bc d3 31 <00 00 00 01> 00 1c e5 ec 0e af 04 69 ==> ESN-Hi = 1
> [  380.854316] ass00000010: a4 fc 08 ad
>
> Note: If I decrypt the same packet with ESN - Hi = 0. It Decrypt successfully means peer machine has used ESN-HI = 0 while encrypting.
>
> To debug further we added trace in "xfrm_replay_seqhi". Following was the output:
>
>  <idle>-0     [003] ..s.   380.967766: xfrm_replay_seqhi: seq_hi 0x 1 seq 0x 1ce5ec bottom 0x 1ce5ee replay seq 0x 1ce62d replay window 0x 40
>
> 1) Is this an expected variable with ESN enables connection?.
>
> 2) If packets are supposed to be dropped can't we avoid decryption overhead.
>
> Following logs are attached
>
> 1) dmesg log
>
> 2) debug patch used to reproduce the issue.
>
> 3) ftace log file
>
> 4) ip xfrm state list
>
>
> Regards
>
> Harsh Jain
>
>