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From:   Matteo Croce <mcroce@redhat.com>
To:     netdev@vger.kernel.org
Cc:     Jay Vosburgh <j.vosburgh@gmail.com>,
        Veaceslav Falico <vfalico@gmail.com>,
        Andy Gospodarek <andy@greyhouse.net>,
        "David S . Miller " <davem@davemloft.net>,
        Stanislav Fomichev <sdf@google.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Song Liu <songliubraving@fb.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Paul Blakey <paulb@mellanox.com>, linux-kernel@vger.kernel.org
Subject: [PATCH net-next 3/4] flow_dissector: extract more ICMP information
Date:   Mon, 21 Oct 2019 22:09:47 +0200
Message-Id: <20191021200948.23775-4-mcroce@redhat.com>
In-Reply-To: <20191021200948.23775-1-mcroce@redhat.com>
References: <20191021200948.23775-1-mcroce@redhat.com>
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Sender: linux-kernel-owner@vger.kernel.org
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The ICMP flow dissector currently parses only the Type and Code fields.
Some ICMP packets (echo, timestamp) have a 16 bit Identifier field which
is used to correlate packets.
Add such field in flow_dissector_key_icmp and replace skb_flow_get_be16()
with a more complex function which populate this field.

Signed-off-by: Matteo Croce <mcroce@redhat.com>
---
 include/net/flow_dissector.h | 10 +++++-
 net/core/flow_dissector.c    | 64 ++++++++++++++++++++++--------------
 2 files changed, 49 insertions(+), 25 deletions(-)

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 7747af3cc500..86c6bf5eab31 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -6,6 +6,8 @@
 #include <linux/in6.h>
 #include <uapi/linux/if_ether.h>
=20
+struct sk_buff;
+
 /**
  * struct flow_dissector_key_control:
  * @thoff: Transport header offset
@@ -160,6 +162,7 @@ struct flow_dissector_key_ports {
  *=09=09icmp: ICMP type (high) and code (low)
  *=09=09type: ICMP type
  *=09=09code: ICMP code
+ *=09=09id:   session identifier
  */
 struct flow_dissector_key_icmp {
 =09union {
@@ -169,6 +172,7 @@ struct flow_dissector_key_icmp {
 =09=09=09u8 code;
 =09=09};
 =09};
+=09u16 id;
 };
=20
 /**
@@ -282,6 +286,7 @@ struct flow_keys {
 =09struct flow_dissector_key_vlan cvlan;
 =09struct flow_dissector_key_keyid keyid;
 =09struct flow_dissector_key_ports ports;
+=09struct flow_dissector_key_icmp icmp;
 =09/* 'addrs' must be the last member */
 =09struct flow_dissector_key_addrs addrs;
 };
@@ -312,10 +317,13 @@ void make_flow_keys_digest(struct flow_keys_digest *d=
igest,
=20
 static inline bool flow_keys_have_l4(const struct flow_keys *keys)
 {
-=09return (keys->ports.ports || keys->tags.flow_label);
+=09return keys->ports.ports || keys->tags.flow_label || keys->icmp.id;
 }
=20
 u32 flow_hash_from_keys(struct flow_keys *keys);
+void skb_flow_get_icmp_tci(const struct sk_buff *skb,
+=09=09=09   struct flow_dissector_key_icmp *key_icmp,
+=09=09=09   void *data, int thoff, int hlen);
=20
 static inline bool dissector_uses_key(const struct flow_dissector *flow_di=
ssector,
 =09=09=09=09      enum flow_dissector_key_id key_id)
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 6443fac65ce8..90dcf6f2ef19 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -147,27 +147,6 @@ int skb_flow_dissector_bpf_prog_detach(const union bpf=
_attr *attr)
 =09mutex_unlock(&flow_dissector_mutex);
 =09return 0;
 }
-/**
- * skb_flow_get_be16 - extract be16 entity
- * @skb: sk_buff to extract from
- * @poff: offset to extract at
- * @data: raw buffer pointer to the packet
- * @hlen: packet header length
- *
- * The function will try to retrieve a be32 entity at
- * offset poff
- */
-static __be16 skb_flow_get_be16(const struct sk_buff *skb, int poff,
-=09=09=09=09void *data, int hlen)
-{
-=09__be16 *u, _u;
-
-=09u =3D __skb_header_pointer(skb, poff, sizeof(_u), data, hlen, &_u);
-=09if (u)
-=09=09return *u;
-
-=09return 0;
-}
=20
 /**
  * __skb_flow_get_ports - extract the upper layer ports and return them
@@ -203,8 +182,44 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb,=
 int thoff, u8 ip_proto,
 }
 EXPORT_SYMBOL(__skb_flow_get_ports);
=20
-/* If FLOW_DISSECTOR_KEY_ICMP is set, get the Type and Code from an ICMP p=
acket
- * using skb_flow_get_be16().
+/**
+ * skb_flow_get_icmp_tci - extract ICMP(6) Type, Code and Identifier field=
s
+ * @skb: sk_buff to extract from
+ * @key_icmp: struct flow_dissector_key_icmp to fill
+ * @data: raw buffer pointer to the packet
+ * @toff: offset to extract at
+ * @hlen: packet header length
+ */
+void skb_flow_get_icmp_tci(const struct sk_buff *skb,
+=09=09=09   struct flow_dissector_key_icmp *key_icmp,
+=09=09=09   void *data, int thoff, int hlen)
+{
+=09struct icmphdr *ih, _ih;
+
+=09ih =3D __skb_header_pointer(skb, thoff, sizeof(_ih), data, hlen, &_ih);
+=09if (!ih)
+=09=09return;
+
+=09key_icmp->type =3D ih->type;
+=09key_icmp->code =3D ih->code;
+=09key_icmp->id =3D 0;
+=09switch (ih->type) {
+=09case ICMP_ECHO:
+=09case ICMP_ECHOREPLY:
+=09case ICMP_TIMESTAMP:
+=09case ICMP_TIMESTAMPREPLY:
+=09case ICMPV6_ECHO_REQUEST:
+=09case ICMPV6_ECHO_REPLY:
+=09=09/* As we use 0 to signal that the Id field is not present,
+=09=09 * avoid confusion with packets without such field
+=09=09 */
+=09=09key_icmp->id =3D ih->un.echo.id ? : 1;
+=09}
+}
+EXPORT_SYMBOL(skb_flow_get_icmp_tci);
+
+/* If FLOW_DISSECTOR_KEY_ICMP is set, dissect an ICMP packet
+ * using skb_flow_get_icmp_tci().
  */
 static void __skb_flow_dissect_icmp(const struct sk_buff *skb,
 =09=09=09=09    struct flow_dissector *flow_dissector,
@@ -219,7 +234,8 @@ static void __skb_flow_dissect_icmp(const struct sk_buf=
f *skb,
 =09key_icmp =3D skb_flow_dissector_target(flow_dissector,
 =09=09=09=09=09     FLOW_DISSECTOR_KEY_ICMP,
 =09=09=09=09=09     target_container);
-=09key_icmp->icmp =3D skb_flow_get_be16(skb, thoff, data, hlen);
+
+=09skb_flow_get_icmp_tci(skb, key_icmp, data, thoff, hlen);
 }
=20
 void skb_flow_dissect_meta(const struct sk_buff *skb,
--=20
2.21.0