[PATCH net-next v2 0/2] net: allow dissecting/matching tunnel control flags

[PATCH net-next v2 0/2] net: allow dissecting/matching tunnel control flags

[Davide Caratti]

Ilya says: "for correct matching on decapsulated packets, we should match
on not only tunnel id and headers, but also on tunnel configuration flags
like TUNNEL_NO_CSUM and TUNNEL_DONT_FRAGMENT. This is done to distinguish
similar tunnels with slightly different configs. And it is important since
tunnel configuration is flow based, i.e. can be different for every packet,
even though the main tunnel port is the same."

 - patch 1 extends the kernel's flow dissector to extract these flags
   from the packet's tunnel metadata.
 - patch 2 extends TC flower to match on any combination of TUNNEL_NO_CSUM,
   TUNNEL_OAM and TUNNEL_DONT_FRAGMENT.

v2:
 - use NL_REQ_ATTR_CHECK() where possible (thanks Jamal)
 - don't overwrite 'ret' in the error path of fl_set_key_flags()

Davide Caratti (2):
  flow_dissector: add support for tunnel control flags
  net/sched: cls_flower: add support for matching tunnel control flags

 include/net/flow_dissector.h | 11 ++++++++
 include/uapi/linux/pkt_cls.h |  3 +++
 net/core/flow_dissector.c    | 13 +++++++++-
 net/sched/cls_flower.c       | 50 +++++++++++++++++++++++++++++++++++-
 4 files changed, 75 insertions(+), 2 deletions(-)

-- 
2.43.0

[PATCH net-next v2 1/2] flow_dissector: add support for tunnel control flags

[Davide Caratti]

dissect [no]csum, [no]dontfrag, [no]oam flags on 'external' tunnels. This
is a prerequisite for matching these control flags using TC flower.

Suggested-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
 include/net/flow_dissector.h | 11 +++++++++++
 net/core/flow_dissector.c    | 13 ++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 1a7131d6cb0e..98a0050d5cc3 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -329,6 +329,16 @@ struct flow_dissector_key_cfm {
 #define FLOW_DIS_CFM_MDL_MASK GENMASK(7, 5)
 #define FLOW_DIS_CFM_MDL_MAX 7
 
+/**
+ * struct flow_dissector_key_enc_flags
+ * @flags: tunnel control flags
+ */
+struct flow_dissector_key_enc_flags {
+	__be16 flags;
+};
+
+#define TUNNEL_FLAGS_PRESENT (TUNNEL_CSUM | TUNNEL_DONT_FRAGMENT | TUNNEL_OAM)
+
 enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_CONTROL, /* struct flow_dissector_key_control */
 	FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
@@ -363,6 +373,7 @@ enum flow_dissector_key_id {
 	FLOW_DISSECTOR_KEY_L2TPV3, /* struct flow_dissector_key_l2tpv3 */
 	FLOW_DISSECTOR_KEY_CFM, /* struct flow_dissector_key_cfm */
 	FLOW_DISSECTOR_KEY_IPSEC, /* struct flow_dissector_key_ipsec */
+	FLOW_DISSECTOR_KEY_ENC_FLAGS, /* struct flow_dissector_key_enc_flags */
 
 	FLOW_DISSECTOR_KEY_MAX,
 };
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 272f09251343..9099a5524d7c 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -382,7 +382,9 @@ skb_flow_dissect_tunnel_info(const struct sk_buff *skb,
 	    !dissector_uses_key(flow_dissector,
 				FLOW_DISSECTOR_KEY_ENC_IP) &&
 	    !dissector_uses_key(flow_dissector,
-				FLOW_DISSECTOR_KEY_ENC_OPTS))
+				FLOW_DISSECTOR_KEY_ENC_OPTS) &&
+	    !dissector_uses_key(flow_dissector,
+				FLOW_DISSECTOR_KEY_ENC_FLAGS))
 		return;
 
 	info = skb_tunnel_info(skb);
@@ -467,6 +469,15 @@ skb_flow_dissect_tunnel_info(const struct sk_buff *skb,
 						TUNNEL_OPTIONS_PRESENT;
 		}
 	}
+
+	if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_FLAGS)) {
+		struct flow_dissector_key_enc_flags *enc_flags;
+
+		enc_flags = skb_flow_dissector_target(flow_dissector,
+						      FLOW_DISSECTOR_KEY_ENC_FLAGS,
+						      target_container);
+		enc_flags->flags = info->key.tun_flags & TUNNEL_FLAGS_PRESENT;
+	}
 }
 EXPORT_SYMBOL(skb_flow_dissect_tunnel_info);
 
-- 
2.43.0

[PATCH net-next v2 2/2] net/sched: cls_flower: add support for matching tunnel control flags

[Davide Caratti]

extend cls_flower to match flags belonging to 'TUNNEL_FLAGS_PRESENT' mask
inside skb tunnel metadata.

Suggested-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
 include/uapi/linux/pkt_cls.h |  3 +++
 net/sched/cls_flower.c       | 50 +++++++++++++++++++++++++++++++++++-
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/pkt_cls.h b/include/uapi/linux/pkt_cls.h
index ea277039f89d..e3394f9d06b7 100644
--- a/include/uapi/linux/pkt_cls.h
+++ b/include/uapi/linux/pkt_cls.h
@@ -554,6 +554,9 @@ enum {
 	TCA_FLOWER_KEY_SPI,		/* be32 */
 	TCA_FLOWER_KEY_SPI_MASK,	/* be32 */
 
+	TCA_FLOWER_KEY_ENC_FLAGS,	/* be16 */
+	TCA_FLOWER_KEY_ENC_FLAGS_MASK,	/* be16 */
+
 	__TCA_FLOWER_MAX,
 };
 
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index efb9d2811b73..8da12256568f 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -74,6 +74,7 @@ struct fl_flow_key {
 	struct flow_dissector_key_l2tpv3 l2tpv3;
 	struct flow_dissector_key_ipsec ipsec;
 	struct flow_dissector_key_cfm cfm;
+	struct flow_dissector_key_enc_flags enc_flags;
 } __aligned(BITS_PER_LONG / 8); /* Ensure that we can do comparisons as longs. */
 
 struct fl_flow_mask_range {
@@ -731,6 +732,10 @@ static const struct nla_policy fl_policy[TCA_FLOWER_MAX + 1] = {
 	[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 },
+	[TCA_FLOWER_KEY_ENC_FLAGS]	= NLA_POLICY_MASK(NLA_BE16,
+							  TUNNEL_FLAGS_PRESENT),
+	[TCA_FLOWER_KEY_ENC_FLAGS_MASK]	= NLA_POLICY_MASK(NLA_BE16,
+							  TUNNEL_FLAGS_PRESENT),
 };
 
 static const struct nla_policy
@@ -1748,6 +1753,21 @@ static int fl_set_key_cfm(struct nlattr **tb,
 	return 0;
 }
 
+static int fl_set_key_enc_flags(struct nlattr **tb, __be16 *flags_key,
+				__be16 *flags_mask, struct netlink_ext_ack *extack)
+{
+	/* mask is mandatory for flags */
+	if (NL_REQ_ATTR_CHECK(extack, NULL, tb, TCA_FLOWER_KEY_ENC_FLAGS_MASK)) {
+		NL_SET_ERR_MSG(extack, "missing enc_flags mask");
+		return -EINVAL;
+	}
+
+	*flags_key = nla_get_be16(tb[TCA_FLOWER_KEY_ENC_FLAGS]);
+	*flags_mask = nla_get_be16(tb[TCA_FLOWER_KEY_ENC_FLAGS_MASK]);
+
+	return 0;
+}
+
 static int fl_set_key(struct net *net, struct nlattr **tb,
 		      struct fl_flow_key *key, struct fl_flow_key *mask,
 		      struct netlink_ext_ack *extack)
@@ -1982,9 +2002,16 @@ static int fl_set_key(struct net *net, struct nlattr **tb,
 	if (ret)
 		return ret;
 
-	if (tb[TCA_FLOWER_KEY_FLAGS])
+	if (tb[TCA_FLOWER_KEY_FLAGS]) {
 		ret = fl_set_key_flags(tb, &key->control.flags,
 				       &mask->control.flags, extack);
+		if (ret)
+			return ret;
+	}
+
+	if (tb[TCA_FLOWER_KEY_ENC_FLAGS])
+		ret = fl_set_key_enc_flags(tb, &key->enc_flags.flags,
+					   &mask->enc_flags.flags, extack);
 
 	return ret;
 }
@@ -2098,6 +2125,8 @@ static void fl_init_dissector(struct flow_dissector *dissector,
 			     FLOW_DISSECTOR_KEY_IPSEC, ipsec);
 	FL_KEY_SET_IF_MASKED(mask, keys, cnt,
 			     FLOW_DISSECTOR_KEY_CFM, cfm);
+	FL_KEY_SET_IF_MASKED(mask, keys, cnt,
+			     FLOW_DISSECTOR_KEY_ENC_FLAGS, enc_flags);
 
 	skb_flow_dissector_init(dissector, keys, cnt);
 }
@@ -3185,6 +3214,22 @@ static int fl_dump_key_cfm(struct sk_buff *skb,
 	return err;
 }
 
+static int fl_dump_key_enc_flags(struct sk_buff *skb,
+				 struct flow_dissector_key_enc_flags *key,
+				 struct flow_dissector_key_enc_flags *mask)
+{
+	if (!memchr_inv(mask, 0, sizeof(*mask)))
+		return 0;
+
+	if (nla_put_be16(skb, TCA_FLOWER_KEY_ENC_FLAGS, key->flags))
+		return -EMSGSIZE;
+
+	if (nla_put_be16(skb, TCA_FLOWER_KEY_ENC_FLAGS_MASK, mask->flags))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
 static int fl_dump_key_options(struct sk_buff *skb, int enc_opt_type,
 			       struct flow_dissector_key_enc_opts *enc_opts)
 {
@@ -3481,6 +3526,9 @@ static int fl_dump_key(struct sk_buff *skb, struct net *net,
 	if (fl_dump_key_cfm(skb, &key->cfm, &mask->cfm))
 		goto nla_put_failure;
 
+	if (fl_dump_key_enc_flags(skb, &key->enc_flags, &mask->enc_flags))
+		goto nla_put_failure;
+
 	return 0;
 
 nla_put_failure:
-- 
2.43.0

Re: [PATCH net-next v2 0/2] net: allow dissecting/matching tunnel control flags

[Jamal Hadi Salim]

On Thu, Feb 1, 2024 at 11:53 AM Davide Caratti <dcaratti@redhat.com> wrote:
>
> Ilya says: "for correct matching on decapsulated packets, we should match
> on not only tunnel id and headers, but also on tunnel configuration flags
> like TUNNEL_NO_CSUM and TUNNEL_DONT_FRAGMENT. This is done to distinguish
> similar tunnels with slightly different configs. And it is important since
> tunnel configuration is flow based, i.e. can be different for every packet,
> even though the main tunnel port is the same."
>
>  - patch 1 extends the kernel's flow dissector to extract these flags
>    from the packet's tunnel metadata.
>  - patch 2 extends TC flower to match on any combination of TUNNEL_NO_CSUM,
>    TUNNEL_OAM and TUNNEL_DONT_FRAGMENT.
>


For the patchset:
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>

cheers,
jamal

> v2:
>  - use NL_REQ_ATTR_CHECK() where possible (thanks Jamal)
>  - don't overwrite 'ret' in the error path of fl_set_key_flags()
>
> Davide Caratti (2):
>   flow_dissector: add support for tunnel control flags
>   net/sched: cls_flower: add support for matching tunnel control flags
>
>  include/net/flow_dissector.h | 11 ++++++++
>  include/uapi/linux/pkt_cls.h |  3 +++
>  net/core/flow_dissector.c    | 13 +++++++++-
>  net/sched/cls_flower.c       | 50 +++++++++++++++++++++++++++++++++++-
>  4 files changed, 75 insertions(+), 2 deletions(-)
>
> --
> 2.43.0
>

Re: [PATCH net-next v2 2/2] net/sched: cls_flower: add support for matching tunnel control flags

[Jakub Kicinski]

On Thu,  1 Feb 2024 17:51:44 +0100 Davide Caratti wrote:
> extend cls_flower to match flags belonging to 'TUNNEL_FLAGS_PRESENT' mask
> inside skb tunnel metadata.

sparse complains about bad endian somewhere in this..
-- 
pw-bot: cr