Subject: Re: [PATCH v1 net-next 2/4] tc: flower: support for SPI

From: Simon Horman <[email-masked]>
Date: Wed, 2 Aug 2023 21:07:35 +0200

+ Dan Carpenter

On Tue, Aug 01, 2023 at 07:10:59AM +0530, Ratheesh Kannoth wrote:
> tc flower rules support to classify ESP/AH
> packets matching SPI field.
> 
> Signed-off-by: Ratheesh Kannoth <[email-masked]>
> ---
>  include/uapi/linux/pkt_cls.h |  3 +++
>  net/sched/cls_flower.c       | 35 +++++++++++++++++++++++++++++++++++
>  2 files changed, 38 insertions(+)
> 
> diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
> index 7865f5a9885b..75506f157340 100644
> --- a/include/uapi/linux/pkt_cls.h
> +++ b/include/uapi/linux/pkt_cls.h
> @@ -598,6 +598,9 @@ enum {
>  
>  	TCA_FLOWER_KEY_CFM,		/* nested */
>  
> +	TCA_FLOWER_KEY_SPI,		/* be32 */
> +	TCA_FLOWER_KEY_SPI_MASK,	/* be32 */
> +
>  	__TCA_FLOWER_MAX,
>  };
>  
> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
> index 8da9d039d964..eca260272845 100644
> --- a/net/sched/cls_flower.c
> +++ b/net/sched/cls_flower.c
> @@ -72,6 +72,7 @@ struct fl_flow_key {
>  	struct flow_dissector_key_num_of_vlans num_of_vlans;
>  	struct flow_dissector_key_pppoe pppoe;
>  	struct flow_dissector_key_l2tpv3 l2tpv3;
> +	struct flow_dissector_key_ipsec ipsec;
>  	struct flow_dissector_key_cfm cfm;
>  } __aligned(BITS_PER_LONG / 8); /* Ensure that we can do comparisons as longs. */
>  
> @@ -726,6 +727,8 @@ static const struct nla_policy fl_policy[TCA_FLOWER_MAX + 1] = {
>  	[TCA_FLOWER_KEY_PPPOE_SID]	= { .type = NLA_U16 },
>  	[TCA_FLOWER_KEY_PPP_PROTO]	= { .type = NLA_U16 },
>  	[TCA_FLOWER_KEY_L2TPV3_SID]	= { .type = NLA_U32 },
> +	[TCA_FLOWER_KEY_SPI]		= { .type = NLA_U32 },
> +	[TCA_FLOWER_KEY_SPI_MASK]	= { .type = NLA_U32 },
>  	[TCA_FLOWER_L2_MISS]		= NLA_POLICY_MAX(NLA_U8, 1),
>  	[TCA_FLOWER_KEY_CFM]		= { .type = NLA_NESTED },
>  };
> @@ -795,6 +798,24 @@ static void fl_set_key_val(struct nlattr **tb,
>  		nla_memcpy(mask, tb[mask_type], len);
>  }
>  
> +static int fl_set_key_spi(struct nlattr **tb, struct fl_flow_key *key,
> +			  struct fl_flow_key *mask,
> +			  struct netlink_ext_ack *extack)
> +{
> +	if (key->basic.ip_proto != IPPROTO_ESP &&
> +	    key->basic.ip_proto != IPPROTO_AH) {
> +		NL_SET_ERR_MSG(extack,
> +			       "Protocol must be either ESP or AH");
> +		return -EINVAL;
> +	}
> +
> +	fl_set_key_val(tb, &key->ipsec.spi,
> +		       TCA_FLOWER_KEY_SPI,
> +		       &mask->ipsec.spi, TCA_FLOWER_KEY_SPI_MASK,
> +		       sizeof(key->ipsec.spi));
> +	return 0;
> +}
> +
>  static int fl_set_key_port_range(struct nlattr **tb, struct fl_flow_key *key,
>  				 struct fl_flow_key *mask,
>  				 struct netlink_ext_ack *extack)
> @@ -1894,6 +1915,12 @@ static int fl_set_key(struct net *net, struct nlattr **tb,
>  			return ret;
>  	}
>  
> +	if (tb[TCA_FLOWER_KEY_SPI]) {
> +		ret = fl_set_key_spi(tb, key, mask, extack);
> +		if (ret)
> +			return ret;
> +	}
> +

Hi Dan,

I'm seeing a warning from Smatch, which I think is a false positive,
but I feel that I should raise. Perhaps you could take a look at it?

net/sched/cls_flower.c:1918 fl_set_key() error: buffer overflow 'tb' 106 <= 108

>  	if (tb[TCA_FLOWER_KEY_ENC_IPV4_SRC] ||
>  	    tb[TCA_FLOWER_KEY_ENC_IPV4_DST]) {
>  		key->enc_control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
> @@ -2066,6 +2093,8 @@ static void fl_init_dissector(struct flow_dissector *dissector,
>  			     FLOW_DISSECTOR_KEY_PPPOE, pppoe);
>  	FL_KEY_SET_IF_MASKED(mask, keys, cnt,
>  			     FLOW_DISSECTOR_KEY_L2TPV3, l2tpv3);
> +	FL_KEY_SET_IF_MASKED(mask, keys, cnt,
> +			     FLOW_DISSECTOR_KEY_IPSEC, ipsec);
>  	FL_KEY_SET_IF_MASKED(mask, keys, cnt,
>  			     FLOW_DISSECTOR_KEY_CFM, cfm);
>  
> @@ -3364,6 +3393,12 @@ static int fl_dump_key(struct sk_buff *skb, struct net *net,
>  				 sizeof(key->l2tpv3.session_id)))
>  		goto nla_put_failure;
>  
> +	if (key->ipsec.spi &&
> +	    fl_dump_key_val(skb, &key->ipsec.spi, TCA_FLOWER_KEY_SPI,
> +			    &mask->ipsec.spi, TCA_FLOWER_KEY_SPI_MASK,
> +			    sizeof(key->ipsec.spi)))
> +		goto nla_put_failure;
> +
>  	if ((key->basic.ip_proto == IPPROTO_TCP ||
>  	     key->basic.ip_proto == IPPROTO_UDP ||
>  	     key->basic.ip_proto == IPPROTO_SCTP) &&
> -- 
> 2.25.1
> 
>