From 5dec597e5cd0f4c3000d120508efa64157d5bd7a Mon Sep 17 00:00:00 2001 From: Matteo Croce Date: Tue, 29 Oct 2019 14:50:52 +0100 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- 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 #include +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 0fb721976f3d..0807df0bde02 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -178,27 +178,6 @@ 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 @@ -234,8 +213,54 @@ __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, @@ -250,7 +275,8 @@ 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,