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Message-Id: <20191029135053.10055-4-mcroce@redhat.com>
Date: Tue, 29 Oct 2019 14:50:52 +0100
From: Matteo Croce <mcroce@...hat.com>
To: netdev@...r.kernel.org
Cc: Jay Vosburgh <j.vosburgh@...il.com>,
Veaceslav Falico <vfalico@...il.com>,
Andy Gospodarek <andy@...yhouse.net>,
"David S . Miller " <davem@...emloft.net>,
Stanislav Fomichev <sdf@...gle.com>,
Daniel Borkmann <daniel@...earbox.net>,
Song Liu <songliubraving@...com>,
Alexei Starovoitov <ast@...nel.org>,
Paul Blakey <paulb@...lanox.com>, linux-kernel@...r.kernel.org
Subject: [PATCH net-next v2 3/4] flow_dissector: extract more ICMP information
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@...hat.com>
---
include/net/flow_dissector.h | 19 +++++----
net/core/flow_dissector.c | 74 ++++++++++++++++++++++++------------
2 files changed, 61 insertions(+), 32 deletions(-)
diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 7747af3cc500..f8541d018848 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>
+struct sk_buff;
+
/**
* struct flow_dissector_key_control:
* @thoff: Transport header offset
@@ -156,19 +158,16 @@ struct flow_dissector_key_ports {
/**
* flow_dissector_key_icmp:
- * @ports: type and code of ICMP header
- * icmp: ICMP type (high) and code (low)
* type: ICMP type
* code: ICMP code
+ * id: session identifier
*/
struct flow_dissector_key_icmp {
- union {
- __be16 icmp;
- struct {
- u8 type;
- u8 code;
- };
+ struct {
+ u8 type;
+ u8 code;
};
+ u16 id;
};
/**
@@ -282,6 +281,7 @@ struct flow_keys {
struct flow_dissector_key_vlan cvlan;
struct flow_dissector_key_keyid keyid;
struct flow_dissector_key_ports ports;
+ struct flow_dissector_key_icmp icmp;
/* 'addrs' must be the last member */
struct flow_dissector_key_addrs addrs;
};
@@ -316,6 +316,9 @@ static inline bool flow_keys_have_l4(const struct flow_keys *keys)
}
u32 flow_hash_from_keys(struct flow_keys *keys);
+void skb_flow_get_icmp_tci(const struct sk_buff *skb,
+ struct flow_dissector_key_icmp *key_icmp,
+ void *data, int thoff, int hlen);
static inline bool dissector_uses_key(const struct flow_dissector *flow_dissector,
enum flow_dissector_key_id key_id)
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 6443fac65ce8..0d014b81b269 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)
mutex_unlock(&flow_dissector_mutex);
return 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,
- void *data, int hlen)
-{
- __be16 *u, _u;
-
- u = __skb_header_pointer(skb, poff, sizeof(_u), data, hlen, &_u);
- if (u)
- return *u;
-
- return 0;
-}
/**
* __skb_flow_get_ports - extract the upper layer ports and return them
@@ -203,8 +182,54 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
}
EXPORT_SYMBOL(__skb_flow_get_ports);
-/* If FLOW_DISSECTOR_KEY_ICMP is set, get the Type and Code from an ICMP packet
- * using skb_flow_get_be16().
+static bool icmp_has_id(u8 type)
+{
+ switch (type) {
+ case ICMP_ECHO:
+ case ICMP_ECHOREPLY:
+ case ICMP_TIMESTAMP:
+ case ICMP_TIMESTAMPREPLY:
+ case ICMPV6_ECHO_REQUEST:
+ case ICMPV6_ECHO_REPLY:
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * skb_flow_get_icmp_tci - extract ICMP(6) Type, Code and Identifier fields
+ * @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,
+ struct flow_dissector_key_icmp *key_icmp,
+ void *data, int thoff, int hlen)
+{
+ struct icmphdr *ih, _ih;
+
+ ih = __skb_header_pointer(skb, thoff, sizeof(_ih), data, hlen, &_ih);
+ if (!ih)
+ return;
+
+ key_icmp->type = ih->type;
+ key_icmp->code = ih->code;
+
+ /* As we use 0 to signal that the Id field is not present,
+ * avoid confusion with packets without such field
+ */
+ if (icmp_has_id(ih->type))
+ key_icmp->id = ih->un.echo.id ? : 1;
+ else
+ key_icmp->id = 0;
+}
+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,
struct flow_dissector *flow_dissector,
@@ -219,7 +244,8 @@ static void __skb_flow_dissect_icmp(const struct sk_buff *skb,
key_icmp = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ICMP,
target_container);
- key_icmp->icmp = skb_flow_get_be16(skb, thoff, data, hlen);
+
+ skb_flow_get_icmp_tci(skb, key_icmp, data, thoff, hlen);
}
void skb_flow_dissect_meta(const struct sk_buff *skb,
--
2.21.0
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