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AJvYcCXCNa+Izyvnp6uTlxb2Z5EyK+2FQSZDRF7Jd2dTg2mO8ZDnpdGEn+3qpSbbL6KgAnmIVEO0Jqg=@vger.kernel.org X-Gm-Message-State: AOJu0Yxnp10eCYtc9IYtjVtf5skfvq3953+Qqh6O1y9XFgNRH/np0atI y1ASEfLgMgfn8GDVE6NYEXrb7w4x6UMlHCibo6pjyJ569Tf9AuYaRdrXwGW+xA== X-Google-Smtp-Source: AGHT+IHOoibAEa0IvBwdYWnlq6KnZD6zWRJfAlagjFiipdD1/ynzgnielHQrvxFCf9vMfEG6mZHhNA== X-Received: by 2002:a05:6a21:e89:b0:1ca:cccd:4a1c with SMTP id adf61e73a8af0-1cc8b5d898amr3002156637.43.1724444174052; Fri, 23 Aug 2024 13:16:14 -0700 (PDT) Received: from TomsPC.home ([2601:646:8300:55f0:9169:3766:b678:8be3]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7143422ec1csm3428525b3a.39.2024.08.23.13.16.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Aug 2024 13:16:13 -0700 (PDT) From: Tom Herbert To: davem@davemloft.net, kuba@kernel.org, edumazet@google.com, netdev@vger.kernel.org, felipe@sipanda.io, willemdebruijn.kernel@gmail.com, pablo@netfilter.org, laforge@gnumonks.org, xeb@mail.ru Cc: Tom Herbert Subject: [PATCH net-next v4 05/13] flow_dissector: UDP encap infrastructure Date: Fri, 23 Aug 2024 13:15:49 -0700 Message-Id: <20240823201557.1794985-6-tom@herbertland.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240823201557.1794985-1-tom@herbertland.com> References: <20240823201557.1794985-1-tom@herbertland.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Add infrastructure for parsing into UDP encapsulations Add function __skb_flow_dissect_udp that is called for IPPROTO_UDP. The flag FLOW_DISSECTOR_F_PARSE_UDP_ENCAPS enables parsing of UDP encapsulations. If the flag is set when parsing a UDP packet then a socket lookup is performed. The offset of the base network header, either an IPv4 or IPv6 header, is tracked and passed to __skb_flow_dissect_udp so that it can perform the socket lookup If a socket is found and it's for a UDP encapsulation (encap_type is set in the UDP socket) then a switch is performed on the encap_type value (cases are UDP_ENCAP_* values) An encapsulated packet in UDP can either be indicated by an EtherType or IP protocol. The processing for dissecting a UDP encap protocol returns a flow dissector return code. If FLOW_DISSECT_RET_PROTO_AGAIN or FLOW_DISSECT_RET_IPPROTO_AGAIN is returned then the corresponding encapsulated protocol is dissected. The nhoff is set to point to the header to process. In the case FLOW_DISSECT_RET_PROTO_AGAIN the EtherType protocol is returned and the IP protocol is set to zero. In the case of FLOW_DISSECT_RET_IPPROTO_AGAIN, the IP protocol is returned and the EtherType protocol is returned unchanged Signed-off-by: Tom Herbert --- include/net/flow_dissector.h | 1 + net/core/flow_dissector.c | 138 +++++++++++++++++++++++++++++++++++ 2 files changed, 139 insertions(+) diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h index ced79dc8e856..8a868a88a6f1 100644 --- a/include/net/flow_dissector.h +++ b/include/net/flow_dissector.h @@ -384,6 +384,7 @@ enum flow_dissector_key_id { #define FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL BIT(1) #define FLOW_DISSECTOR_F_STOP_AT_ENCAP BIT(2) #define FLOW_DISSECTOR_F_STOP_BEFORE_ENCAP BIT(3) +#define FLOW_DISSECTOR_F_PARSE_UDP_ENCAPS BIT(4) struct flow_dissector_key { enum flow_dissector_key_id key_id; diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 5170676a224c..f3134804a1db 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -806,6 +807,134 @@ __skb_flow_dissect_batadv(const struct sk_buff *skb, return FLOW_DISSECT_RET_PROTO_AGAIN; } +static enum flow_dissect_ret +__skb_flow_dissect_udp(const struct sk_buff *skb, const struct net *net, + struct flow_dissector *flow_dissector, + void *target_container, const void *data, + int *p_nhoff, int hlen, __be16 *p_proto, + u8 *p_ip_proto, int base_nhoff, unsigned int flags, + unsigned int num_hdrs) +{ + enum flow_dissect_ret ret; + struct udphdr _udph; + int nhoff; + + if (!(flags & FLOW_DISSECTOR_F_PARSE_UDP_ENCAPS)) + return FLOW_DISSECT_RET_OUT_GOOD; + + /* Check that the netns for the skb device is the same as the caller's, + * and only dissect UDP if we haven't yet encountered any encapsulation. + * The goal is to ensure that the socket lookup is being done in the + * right netns. Encapsulations may push packets into different name + * spaces, so this scheme is restricting UDP dissection to cases where + * they are in the same name spaces or at least the original name space. + * This should capture the majority of use cases for UDP encaps, and + * if we do encounter a UDP encapsulation within a different namespace + * then the only effect is we don't attempt UDP dissection + */ + if (dev_net(skb->dev) != net || num_hdrs > 0) + return FLOW_DISSECT_RET_OUT_GOOD; + + switch (*p_proto) { +#ifdef CONFIG_INET + case htons(ETH_P_IP): { + const struct udphdr *udph; + const struct iphdr *iph; + struct iphdr _iph; + struct sock *sk; + + iph = __skb_header_pointer(skb, base_nhoff, sizeof(_iph), data, + hlen, &_iph); + if (!iph) + return FLOW_DISSECT_RET_OUT_BAD; + + udph = __skb_header_pointer(skb, *p_nhoff, sizeof(_udph), data, + hlen, &_udph); + if (!udph) + return FLOW_DISSECT_RET_OUT_BAD; + + rcu_read_lock(); + /* Look up the UDPv4 socket and get the encap_type */ + sk = __udp4_lib_lookup(net, iph->saddr, udph->source, + iph->daddr, udph->dest, + inet_iif(skb), inet_sdif(skb), + net->ipv4.udp_table, NULL); + if (!sk || !udp_sk(sk)->encap_type) { + rcu_read_unlock(); + return FLOW_DISSECT_RET_OUT_GOOD; + } + + encap_type = udp_sk(sk)->encap_type; + rcu_read_unlock(); + + break; + } +#if IS_ENABLED(CONFIG_IPV6) + case htons(ETH_P_IPV6): { + const struct ipv6hdr *iph; + const struct udphdr *udph; + struct ipv6hdr _iph; + struct sock *sk; + + if (!likely(ipv6_stub)) + return FLOW_DISSECT_RET_OUT_GOOD; + + iph = __skb_header_pointer(skb, base_nhoff, sizeof(_iph), data, + hlen, &_iph); + if (!iph) + return FLOW_DISSECT_RET_OUT_BAD; + + udph = __skb_header_pointer(skb, *p_nhoff, sizeof(_udph), data, + hlen, &_udph); + if (!udph) + return FLOW_DISSECT_RET_OUT_BAD; + + rcu_read_lock(); + /* Look up the UDPv6 socket and get the encap_type */ + sk = ipv6_stub->udp6_lib_lookup(net, + &iph->saddr, udph->source, + &iph->daddr, udph->dest, + inet_iif(skb), inet_sdif(skb), + net->ipv4.udp_table, NULL); + + if (!sk || !udp_sk(sk)->encap_type) { + rcu_read_unlock(); + return FLOW_DISSECT_RET_OUT_GOOD; + } + + encap_type = udp_sk(sk)->encap_type; + rcu_read_unlock(); + + break; + } +#endif /* CONFIG_IPV6 */ +#endif /* CONFIG_INET */ + default: + return FLOW_DISSECT_RET_OUT_GOOD; + } + + nhoff = *p_nhoff + sizeof(_udph); + ret = FLOW_DISSECT_RET_OUT_GOOD; + + switch (encap_type) { + default: + break; + } + + switch (ret) { + case FLOW_DISSECT_RET_PROTO_AGAIN: + *p_ip_proto = 0; + fallthrough; + case FLOW_DISSECT_RET_IPPROTO_AGAIN: + *p_nhoff = nhoff; + break; + default: + break; + } + + return ret; +} + static void __skb_flow_dissect_tcp(const struct sk_buff *skb, struct flow_dissector *flow_dissector, @@ -1046,6 +1175,7 @@ bool __skb_flow_dissect(const struct net *net, int mpls_lse = 0; int num_hdrs = 0; u8 ip_proto = 0; + int base_nhoff; bool ret; if (!data) { @@ -1168,6 +1298,7 @@ bool __skb_flow_dissect(const struct net *net, proto_again: fdret = FLOW_DISSECT_RET_CONTINUE; + base_nhoff = nhoff; switch (proto) { case htons(ETH_P_IP): { @@ -1649,6 +1780,13 @@ bool __skb_flow_dissect(const struct net *net, data, nhoff, hlen); break; + case IPPROTO_UDP: + fdret = __skb_flow_dissect_udp(skb, net, flow_dissector, + target_container, data, &nhoff, + hlen, &proto, &ip_proto, + base_nhoff, flags, num_hdrs); + break; + case IPPROTO_ICMP: case IPPROTO_ICMPV6: __skb_flow_dissect_icmp(skb, flow_dissector, target_container,