move clatd.c bpf program to mainline
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I555cbbc4c6ae8bb8016b95dff49a4c9b353750e2
diff --git a/bpf_progs/Android.bp b/bpf_progs/Android.bp
index dec0385..bdb987b 100644
--- a/bpf_progs/Android.bp
+++ b/bpf_progs/Android.bp
@@ -27,20 +27,3 @@
name: "netd_bpf_progs_headers",
export_include_dirs: ["."],
}
-
-//
-// bpf kernel programs
-//
-bpf {
- name: "clatd.o",
- srcs: ["clatd.c"],
- cflags: [
- "-Wall",
- "-Werror",
- ],
- include_dirs: [
- "frameworks/libs/net/common/netd/libnetdutils/include",
- // TODO: remove when this module is moved to Tethering module
- "packages/modules/Connectivity/bpf_progs",
- ],
-}
diff --git a/bpf_progs/clatd.c b/bpf_progs/clatd.c
deleted file mode 100644
index dc646c3..0000000
--- a/bpf_progs/clatd.c
+++ /dev/null
@@ -1,322 +0,0 @@
-/*
- * Copyright (C) 2019 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <linux/bpf.h>
-#include <linux/if.h>
-#include <linux/if_ether.h>
-#include <linux/in.h>
-#include <linux/in6.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <linux/pkt_cls.h>
-#include <linux/swab.h>
-#include <stdbool.h>
-#include <stdint.h>
-
-// bionic kernel uapi linux/udp.h header is munged...
-#define __kernel_udphdr udphdr
-#include <linux/udp.h>
-
-#include "bpf_helpers.h"
-#include "bpf_net_helpers.h"
-#include "bpf_shared.h"
-
-// From kernel:include/net/ip.h
-#define IP_DF 0x4000 // Flag: "Don't Fragment"
-
-DEFINE_BPF_MAP_GRW(clat_ingress6_map, HASH, ClatIngress6Key, ClatIngress6Value, 16, AID_SYSTEM)
-
-static inline __always_inline int nat64(struct __sk_buff* skb, bool is_ethernet) {
- const int l2_header_size = is_ethernet ? sizeof(struct ethhdr) : 0;
- void* data = (void*)(long)skb->data;
- const void* data_end = (void*)(long)skb->data_end;
- const struct ethhdr* const eth = is_ethernet ? data : NULL; // used iff is_ethernet
- const struct ipv6hdr* const ip6 = is_ethernet ? (void*)(eth + 1) : data;
-
- // Require ethernet dst mac address to be our unicast address.
- if (is_ethernet && (skb->pkt_type != PACKET_HOST)) return TC_ACT_PIPE;
-
- // Must be meta-ethernet IPv6 frame
- if (skb->protocol != htons(ETH_P_IPV6)) return TC_ACT_PIPE;
-
- // Must have (ethernet and) ipv6 header
- if (data + l2_header_size + sizeof(*ip6) > data_end) return TC_ACT_PIPE;
-
- // Ethertype - if present - must be IPv6
- if (is_ethernet && (eth->h_proto != htons(ETH_P_IPV6))) return TC_ACT_PIPE;
-
- // IP version must be 6
- if (ip6->version != 6) return TC_ACT_PIPE;
-
- // Maximum IPv6 payload length that can be translated to IPv4
- if (ntohs(ip6->payload_len) > 0xFFFF - sizeof(struct iphdr)) return TC_ACT_PIPE;
-
- switch (ip6->nexthdr) {
- case IPPROTO_TCP: // For TCP & UDP the checksum neutrality of the chosen IPv6
- case IPPROTO_UDP: // address means there is no need to update their checksums.
- case IPPROTO_GRE: // We do not need to bother looking at GRE/ESP headers,
- case IPPROTO_ESP: // since there is never a checksum to update.
- break;
-
- default: // do not know how to handle anything else
- return TC_ACT_PIPE;
- }
-
- ClatIngress6Key k = {
- .iif = skb->ifindex,
- .pfx96.in6_u.u6_addr32 =
- {
- ip6->saddr.in6_u.u6_addr32[0],
- ip6->saddr.in6_u.u6_addr32[1],
- ip6->saddr.in6_u.u6_addr32[2],
- },
- .local6 = ip6->daddr,
- };
-
- ClatIngress6Value* v = bpf_clat_ingress6_map_lookup_elem(&k);
-
- if (!v) return TC_ACT_PIPE;
-
- struct ethhdr eth2; // used iff is_ethernet
- if (is_ethernet) {
- eth2 = *eth; // Copy over the ethernet header (src/dst mac)
- eth2.h_proto = htons(ETH_P_IP); // But replace the ethertype
- }
-
- struct iphdr ip = {
- .version = 4, // u4
- .ihl = sizeof(struct iphdr) / sizeof(__u32), // u4
- .tos = (ip6->priority << 4) + (ip6->flow_lbl[0] >> 4), // u8
- .tot_len = htons(ntohs(ip6->payload_len) + sizeof(struct iphdr)), // u16
- .id = 0, // u16
- .frag_off = htons(IP_DF), // u16
- .ttl = ip6->hop_limit, // u8
- .protocol = ip6->nexthdr, // u8
- .check = 0, // u16
- .saddr = ip6->saddr.in6_u.u6_addr32[3], // u32
- .daddr = v->local4.s_addr, // u32
- };
-
- // Calculate the IPv4 one's complement checksum of the IPv4 header.
- __wsum sum4 = 0;
- for (int i = 0; i < sizeof(ip) / sizeof(__u16); ++i) {
- sum4 += ((__u16*)&ip)[i];
- }
- // Note that sum4 is guaranteed to be non-zero by virtue of ip.version == 4
- sum4 = (sum4 & 0xFFFF) + (sum4 >> 16); // collapse u32 into range 1 .. 0x1FFFE
- sum4 = (sum4 & 0xFFFF) + (sum4 >> 16); // collapse any potential carry into u16
- ip.check = (__u16)~sum4; // sum4 cannot be zero, so this is never 0xFFFF
-
- // Calculate the *negative* IPv6 16-bit one's complement checksum of the IPv6 header.
- __wsum sum6 = 0;
- // We'll end up with a non-zero sum due to ip6->version == 6 (which has '0' bits)
- for (int i = 0; i < sizeof(*ip6) / sizeof(__u16); ++i) {
- sum6 += ~((__u16*)ip6)[i]; // note the bitwise negation
- }
-
- // Note that there is no L4 checksum update: we are relying on the checksum neutrality
- // of the ipv6 address chosen by netd's ClatdController.
-
- // Packet mutations begin - point of no return, but if this first modification fails
- // the packet is probably still pristine, so let clatd handle it.
- if (bpf_skb_change_proto(skb, htons(ETH_P_IP), 0)) return TC_ACT_PIPE;
-
- // This takes care of updating the skb->csum field for a CHECKSUM_COMPLETE packet.
- //
- // In such a case, skb->csum is a 16-bit one's complement sum of the entire payload,
- // thus we need to subtract out the ipv6 header's sum, and add in the ipv4 header's sum.
- // However, by construction of ip.check above the checksum of an ipv4 header is zero.
- // Thus we only need to subtract the ipv6 header's sum, which is the same as adding
- // in the sum of the bitwise negation of the ipv6 header.
- //
- // bpf_csum_update() always succeeds if the skb is CHECKSUM_COMPLETE and returns an error
- // (-ENOTSUPP) if it isn't. So we just ignore the return code.
- //
- // if (skb->ip_summed == CHECKSUM_COMPLETE)
- // return (skb->csum = csum_add(skb->csum, csum));
- // else
- // return -ENOTSUPP;
- bpf_csum_update(skb, sum6);
-
- // bpf_skb_change_proto() invalidates all pointers - reload them.
- data = (void*)(long)skb->data;
- data_end = (void*)(long)skb->data_end;
-
- // I cannot think of any valid way for this error condition to trigger, however I do
- // believe the explicit check is required to keep the in kernel ebpf verifier happy.
- if (data + l2_header_size + sizeof(struct iphdr) > data_end) return TC_ACT_SHOT;
-
- if (is_ethernet) {
- struct ethhdr* new_eth = data;
-
- // Copy over the updated ethernet header
- *new_eth = eth2;
-
- // Copy over the new ipv4 header.
- *(struct iphdr*)(new_eth + 1) = ip;
- } else {
- // Copy over the new ipv4 header without an ethernet header.
- *(struct iphdr*)data = ip;
- }
-
- // Redirect, possibly back to same interface, so tcpdump sees packet twice.
- if (v->oif) return bpf_redirect(v->oif, BPF_F_INGRESS);
-
- // Just let it through, tcpdump will not see IPv4 packet.
- return TC_ACT_PIPE;
-}
-
-DEFINE_BPF_PROG("schedcls/ingress6/clat_ether", AID_ROOT, AID_SYSTEM, sched_cls_ingress6_clat_ether)
-(struct __sk_buff* skb) {
- return nat64(skb, true);
-}
-
-DEFINE_BPF_PROG("schedcls/ingress6/clat_rawip", AID_ROOT, AID_SYSTEM, sched_cls_ingress6_clat_rawip)
-(struct __sk_buff* skb) {
- return nat64(skb, false);
-}
-
-DEFINE_BPF_MAP_GRW(clat_egress4_map, HASH, ClatEgress4Key, ClatEgress4Value, 16, AID_SYSTEM)
-
-DEFINE_BPF_PROG("schedcls/egress4/clat_ether", AID_ROOT, AID_SYSTEM, sched_cls_egress4_clat_ether)
-(struct __sk_buff* skb) {
- return TC_ACT_PIPE;
-}
-
-DEFINE_BPF_PROG("schedcls/egress4/clat_rawip", AID_ROOT, AID_SYSTEM, sched_cls_egress4_clat_rawip)
-(struct __sk_buff* skb) {
- void* data = (void*)(long)skb->data;
- const void* data_end = (void*)(long)skb->data_end;
- const struct iphdr* const ip4 = data;
-
- // Must be meta-ethernet IPv4 frame
- if (skb->protocol != htons(ETH_P_IP)) return TC_ACT_PIPE;
-
- // Must have ipv4 header
- if (data + sizeof(*ip4) > data_end) return TC_ACT_PIPE;
-
- // IP version must be 4
- if (ip4->version != 4) return TC_ACT_PIPE;
-
- // We cannot handle IP options, just standard 20 byte == 5 dword minimal IPv4 header
- if (ip4->ihl != 5) return TC_ACT_PIPE;
-
- // Calculate the IPv4 one's complement checksum of the IPv4 header.
- __wsum sum4 = 0;
- for (int i = 0; i < sizeof(*ip4) / sizeof(__u16); ++i) {
- sum4 += ((__u16*)ip4)[i];
- }
- // Note that sum4 is guaranteed to be non-zero by virtue of ip4->version == 4
- sum4 = (sum4 & 0xFFFF) + (sum4 >> 16); // collapse u32 into range 1 .. 0x1FFFE
- sum4 = (sum4 & 0xFFFF) + (sum4 >> 16); // collapse any potential carry into u16
- // for a correct checksum we should get *a* zero, but sum4 must be positive, ie 0xFFFF
- if (sum4 != 0xFFFF) return TC_ACT_PIPE;
-
- // Minimum IPv4 total length is the size of the header
- if (ntohs(ip4->tot_len) < sizeof(*ip4)) return TC_ACT_PIPE;
-
- // We are incapable of dealing with IPv4 fragments
- if (ip4->frag_off & ~htons(IP_DF)) return TC_ACT_PIPE;
-
- switch (ip4->protocol) {
- case IPPROTO_TCP: // For TCP & UDP the checksum neutrality of the chosen IPv6
- case IPPROTO_GRE: // address means there is no need to update their checksums.
- case IPPROTO_ESP: // We do not need to bother looking at GRE/ESP headers,
- break; // since there is never a checksum to update.
-
- case IPPROTO_UDP: // See above comment, but must also have UDP header...
- if (data + sizeof(*ip4) + sizeof(struct udphdr) > data_end) return TC_ACT_PIPE;
- const struct udphdr* uh = (const struct udphdr*)(ip4 + 1);
- // If IPv4/UDP checksum is 0 then fallback to clatd so it can calculate the
- // checksum. Otherwise the network or more likely the NAT64 gateway might
- // drop the packet because in most cases IPv6/UDP packets with a zero checksum
- // are invalid. See RFC 6935. TODO: calculate checksum via bpf_csum_diff()
- if (!uh->check) return TC_ACT_PIPE;
- break;
-
- default: // do not know how to handle anything else
- return TC_ACT_PIPE;
- }
-
- ClatEgress4Key k = {
- .iif = skb->ifindex,
- .local4.s_addr = ip4->saddr,
- };
-
- ClatEgress4Value* v = bpf_clat_egress4_map_lookup_elem(&k);
-
- if (!v) return TC_ACT_PIPE;
-
- // Translating without redirecting doesn't make sense.
- if (!v->oif) return TC_ACT_PIPE;
-
- // This implementation is currently limited to rawip.
- if (v->oifIsEthernet) return TC_ACT_PIPE;
-
- struct ipv6hdr ip6 = {
- .version = 6, // __u8:4
- .priority = ip4->tos >> 4, // __u8:4
- .flow_lbl = {(ip4->tos & 0xF) << 4, 0, 0}, // __u8[3]
- .payload_len = htons(ntohs(ip4->tot_len) - 20), // __be16
- .nexthdr = ip4->protocol, // __u8
- .hop_limit = ip4->ttl, // __u8
- .saddr = v->local6, // struct in6_addr
- .daddr = v->pfx96, // struct in6_addr
- };
- ip6.daddr.in6_u.u6_addr32[3] = ip4->daddr;
-
- // Calculate the IPv6 16-bit one's complement checksum of the IPv6 header.
- __wsum sum6 = 0;
- // We'll end up with a non-zero sum due to ip6.version == 6
- for (int i = 0; i < sizeof(ip6) / sizeof(__u16); ++i) {
- sum6 += ((__u16*)&ip6)[i];
- }
-
- // Note that there is no L4 checksum update: we are relying on the checksum neutrality
- // of the ipv6 address chosen by netd's ClatdController.
-
- // Packet mutations begin - point of no return, but if this first modification fails
- // the packet is probably still pristine, so let clatd handle it.
- if (bpf_skb_change_proto(skb, htons(ETH_P_IPV6), 0)) return TC_ACT_PIPE;
-
- // This takes care of updating the skb->csum field for a CHECKSUM_COMPLETE packet.
- //
- // In such a case, skb->csum is a 16-bit one's complement sum of the entire payload,
- // thus we need to subtract out the ipv4 header's sum, and add in the ipv6 header's sum.
- // However, we've already verified the ipv4 checksum is correct and thus 0.
- // Thus we only need to add the ipv6 header's sum.
- //
- // bpf_csum_update() always succeeds if the skb is CHECKSUM_COMPLETE and returns an error
- // (-ENOTSUPP) if it isn't. So we just ignore the return code (see above for more details).
- bpf_csum_update(skb, sum6);
-
- // bpf_skb_change_proto() invalidates all pointers - reload them.
- data = (void*)(long)skb->data;
- data_end = (void*)(long)skb->data_end;
-
- // I cannot think of any valid way for this error condition to trigger, however I do
- // believe the explicit check is required to keep the in kernel ebpf verifier happy.
- if (data + sizeof(ip6) > data_end) return TC_ACT_SHOT;
-
- // Copy over the new ipv6 header without an ethernet header.
- *(struct ipv6hdr*)data = ip6;
-
- // Redirect to non v4-* interface. Tcpdump only sees packet after this redirect.
- return bpf_redirect(v->oif, 0 /* this is effectively BPF_F_EGRESS */);
-}
-
-LICENSE("Apache 2.0");
-CRITICAL("netd");
diff --git a/server/Android.bp b/server/Android.bp
index 00423a2..a5a8d80 100644
--- a/server/Android.bp
+++ b/server/Android.bp
@@ -100,7 +100,6 @@
init_rc: ["netd.rc"],
required: [
"bpfloader",
- "clatd.o",
],
header_libs: ["bpf_connectivity_headers"],
shared_libs: [
