netdev - Re: [PATCH ipsec 2/2] xfrm: Log input direction mismatch error in one place

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Date: Fri, 14 Jun 2024 13:10:17 +0100
From: Simon Horman <horms@...nel.org>
To: Antony Antony <antony.antony@...unet.com>
Cc: netdev@...r.kernel.org, Steffen Klassert <steffen.klassert@...unet.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Sabrina Dubroca <sd@...asysnail.net>
Subject: Re: [PATCH ipsec 2/2] xfrm: Log input direction mismatch error in
 one place

On Tue, Jun 11, 2024 at 08:32:15AM +0200, Antony Antony wrote:
> Previously, the offload data path decrypted the packet before checking
> the direction, leading to error logging and packet dropping. However,
> dropped packets wouldn't be visible in tcpdump or audit log.
> 
> With this fix, the offload path, upon noticing SA direction mismatch,
> will pass the packet to the stack without decrypting it. The L3 layer
> will then log the error, audit, and drop ESP without decrypting or
> decapsulating it.
> 
> This also ensures that the slow path records the error and audit log,
> making dropped packets visible in tcpdump.
> 
> Fixes: 304b44f0d5a4 ("xfrm: Add dir validation to "in" data path lookup")
> Signed-off-by: Antony Antony <antony.antony@...unet.com>

Thanks Antony,

The comment below notwithstanding, this looks good to me.
Reviewed-by: Simon Horman <horms@...nel.org>

> ---
>  net/ipv4/esp4_offload.c | 7 +++++++
>  net/ipv6/esp6_offload.c | 7 +++++++
>  net/xfrm/xfrm_input.c   | 5 -----
>  3 files changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
> index b3271957ad9a..3f28ecbdcaef 100644
> --- a/net/ipv4/esp4_offload.c
> +++ b/net/ipv4/esp4_offload.c
> @@ -56,6 +56,13 @@ static struct sk_buff *esp4_gro_receive(struct list_head *head,
>  		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
>  				      (xfrm_address_t *)&ip_hdr(skb)->daddr,
>  				      spi, IPPROTO_ESP, AF_INET);
> +
> +		if (unlikely(x && x->dir && x->dir != XFRM_SA_DIR_IN)) {
> +			/* non-offload path will record the error and audit log */
> +			xfrm_state_put(x);
> +			x = NULL;
> +		}
> +
>  		if (!x)
>  			goto out_reset;
>  
> diff --git a/net/ipv6/esp6_offload.c b/net/ipv6/esp6_offload.c
> index 527b7caddbc6..919ebfabbe4e 100644
> --- a/net/ipv6/esp6_offload.c
> +++ b/net/ipv6/esp6_offload.c
> @@ -83,6 +83,13 @@ static struct sk_buff *esp6_gro_receive(struct list_head *head,
>  		x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
>  				      (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
>  				      spi, IPPROTO_ESP, AF_INET6);
> +
> +		if (unlikely(x && x->dir && x->dir != XFRM_SA_DIR_IN)) {
> +			/* non-offload path will record the error and audit log */
> +			xfrm_state_put(x);
> +			x = NULL;
> +		}
> +
>  		if (!x)
>  			goto out_reset;
>  

The logic in the two hunks above seems to be duplicated.
FWIIW, I think it would be nice to consolidate it.

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