Re: [PATCH net-next] flow_dissector: Add IPSEC dissectors
From: Leon Romanovsky
Date: Tue Jul 25 2023 - 01:12:10 EST
On Tue, Jul 25, 2023 at 08:54:51AM +0530, Ratheesh Kannoth wrote:
> Support for dissecting IPSEC field SPI (which is
> 32bits in size) for ESP and AH packets.
Please don't add extra space in the beginning of lines.
>
> This implementation does not support NAT-T
> (encapsulation of ESP packets over UDP).
And how will user distinguish kernel which supports flow_dissector with
NAT-T vs. without NAT-T?
>
> Signed-off-by: Ratheesh Kannoth <rkannoth@xxxxxxxxxxx>
> ---
> include/net/flow_dissector.h | 9 ++++++
> include/net/flow_offload.h | 6 ++++
> include/uapi/linux/pkt_cls.h | 3 ++
> net/core/flow_dissector.c | 53 +++++++++++++++++++++++++++++++++++-
> net/core/flow_offload.c | 7 +++++
> net/sched/cls_flower.c | 18 ++++++++++++
> 6 files changed, 95 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
> index 8664ed4fbbdf..ffec739f049a 100644
> --- a/include/net/flow_dissector.h
> +++ b/include/net/flow_dissector.h
> @@ -301,6 +301,14 @@ struct flow_dissector_key_l2tpv3 {
> __be32 session_id;
> };
>
> +/**
> + * struct flow_dissector_key_ipsec:
> + * @spi: identifier for a ipsec connection
> + */
> +struct flow_dissector_key_ipsec {
> + __be32 spi;
> +};
> +
> /**
> * struct flow_dissector_key_cfm
> * @mdl_ver: maintenance domain level (mdl) and cfm protocol version
> @@ -353,6 +361,7 @@ enum flow_dissector_key_id {
> FLOW_DISSECTOR_KEY_NUM_OF_VLANS, /* struct flow_dissector_key_num_of_vlans */
> FLOW_DISSECTOR_KEY_PPPOE, /* struct flow_dissector_key_pppoe */
> FLOW_DISSECTOR_KEY_L2TPV3, /* struct flow_dissector_key_l2tpv3 */
> + FLOW_DISSECTOR_KEY_IPSEC, /* struct flow_dissector_key_ipsec */
> FLOW_DISSECTOR_KEY_CFM, /* struct flow_dissector_key_cfm */
>
> FLOW_DISSECTOR_KEY_MAX,
> diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h
> index 118082eae48c..9efa9a59e81f 100644
> --- a/include/net/flow_offload.h
> +++ b/include/net/flow_offload.h
> @@ -64,6 +64,10 @@ struct flow_match_tcp {
> struct flow_dissector_key_tcp *key, *mask;
> };
>
> +struct flow_match_ipsec {
> + struct flow_dissector_key_ipsec *key, *mask;
> +};
> +
> struct flow_match_mpls {
> struct flow_dissector_key_mpls *key, *mask;
> };
> @@ -116,6 +120,8 @@ void flow_rule_match_ports_range(const struct flow_rule *rule,
> struct flow_match_ports_range *out);
> void flow_rule_match_tcp(const struct flow_rule *rule,
> struct flow_match_tcp *out);
> +void flow_rule_match_ipsec(const struct flow_rule *rule,
> + struct flow_match_ipsec *out);
> void flow_rule_match_icmp(const struct flow_rule *rule,
> struct flow_match_icmp *out);
> void flow_rule_match_mpls(const struct flow_rule *rule,
> diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
> index 7865f5a9885b..a90b0e3d351f 100644
> --- a/include/uapi/linux/pkt_cls.h
> +++ b/include/uapi/linux/pkt_cls.h
> @@ -594,6 +594,9 @@ enum {
>
> TCA_FLOWER_KEY_L2TPV3_SID, /* be32 */
>
> + TCA_FLOWER_KEY_SPI, /* be32 */
> + TCA_FLOWER_KEY_SPI_MASK, /* be32 */
> +
> TCA_FLOWER_L2_MISS, /* u8 */
>
> TCA_FLOWER_KEY_CFM, /* nested */
> diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> index 85a2d0d9bd39..7162594d7940 100644
> --- a/net/core/flow_dissector.c
> +++ b/net/core/flow_dissector.c
> @@ -205,6 +205,50 @@ static void __skb_flow_dissect_icmp(const struct sk_buff *skb,
> skb_flow_get_icmp_tci(skb, key_icmp, data, thoff, hlen);
> }
>
> +static void __skb_flow_dissect_ah(const struct sk_buff *skb,
> + struct flow_dissector *flow_dissector,
> + void *target_container, const void *data,
> + int nhoff, int hlen)
> +{
> + struct flow_dissector_key_ipsec *key_ah;
> + struct ip_auth_hdr _hdr, *hdr;
In tunnel mode, this struct is ip_esp_hdr and not ip_auth_hdr.
Thanks
> +
> + if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IPSEC))
> + return;
> +
> + hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
> + if (!hdr)
> + return;
> +
> + key_ah = skb_flow_dissector_target(flow_dissector,
> + FLOW_DISSECTOR_KEY_IPSEC,
> + target_container);
> +
> + key_ah->spi = hdr->spi;
> +}
> +
> +static void __skb_flow_dissect_esp(const struct sk_buff *skb,
> + struct flow_dissector *flow_dissector,
> + void *target_container, const void *data,
> + int nhoff, int hlen)
> +{
> + struct flow_dissector_key_ipsec *key_esp;
> + struct ip_esp_hdr _hdr, *hdr;
> +
> + if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IPSEC))
> + return;
> +
> + hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
> + if (!hdr)
> + return;
> +
> + key_esp = skb_flow_dissector_target(flow_dissector,
> + FLOW_DISSECTOR_KEY_IPSEC,
> + target_container);
> +
> + key_esp->spi = hdr->spi;
> +}
> +
> static void __skb_flow_dissect_l2tpv3(const struct sk_buff *skb,
> struct flow_dissector *flow_dissector,
> void *target_container, const void *data,
> @@ -1571,7 +1615,14 @@ bool __skb_flow_dissect(const struct net *net,
> __skb_flow_dissect_l2tpv3(skb, flow_dissector, target_container,
> data, nhoff, hlen);
> break;
> -
> + case IPPROTO_ESP:
> + __skb_flow_dissect_esp(skb, flow_dissector, target_container,
> + data, nhoff, hlen);
> + break;
> + case IPPROTO_AH:
> + __skb_flow_dissect_ah(skb, flow_dissector, target_container,
> + data, nhoff, hlen);
> + break;
> default:
> break;
> }
> diff --git a/net/core/flow_offload.c b/net/core/flow_offload.c
> index acfc1f88ea79..bc5169482710 100644
> --- a/net/core/flow_offload.c
> +++ b/net/core/flow_offload.c
> @@ -146,6 +146,13 @@ void flow_rule_match_tcp(const struct flow_rule *rule,
> }
> EXPORT_SYMBOL(flow_rule_match_tcp);
>
> +void flow_rule_match_ipsec(const struct flow_rule *rule,
> + struct flow_match_ipsec *out)
> +{
> + FLOW_DISSECTOR_MATCH(rule, FLOW_DISSECTOR_KEY_IPSEC, out);
> +}
> +EXPORT_SYMBOL(flow_rule_match_ipsec);
> +
> void flow_rule_match_icmp(const struct flow_rule *rule,
> struct flow_match_icmp *out)
> {
> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
> index 8da9d039d964..7ba839057d3c 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 },
> };
> @@ -1894,6 +1897,13 @@ static int fl_set_key(struct net *net, struct nlattr **tb,
> return ret;
> }
>
> + if (tb[TCA_FLOWER_KEY_SPI]) {
> + fl_set_key_val(tb, &key->ipsec.spi,
> + TCA_FLOWER_KEY_SPI,
> + &mask->ipsec.spi, TCA_FLOWER_KEY_SPI_MASK,
> + sizeof(key->ipsec.spi));
> + }
> +
> 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 +2076,8 @@ 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 +3376,12 @@ 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
>
>