Merge cherrypicks of [12212499, 12213565, 12213741, 12213742, 12213743, 12213702, 12213319, 12213491, 12213118, 12213065, 12213602, 12213603] into rvc-releaseandroid-vts-11.0_r1android-security-11.0.0_r73android-security-11.0.0_r72android-security-11.0.0_r71android-security-11.0.0_r70android-security-11.0.0_r69android-security-11.0.0_r68android-security-11.0.0_r67android-security-11.0.0_r66android-security-11.0.0_r65android-security-11.0.0_r64android-security-11.0.0_r63android-security-11.0.0_r62android-security-11.0.0_r61android-security-11.0.0_r60android-security-11.0.0_r59android-security-11.0.0_r58android-security-11.0.0_r57android-security-11.0.0_r56android-security-11.0.0_r55android-security-11.0.0_r54android-security-11.0.0_r53android-security-11.0.0_r52android-security-11.0.0_r51android-security-11.0.0_r50android-security-11.0.0_r49android-security-11.0.0_r1android-cts-11.0_r1android-11.0.0_r5android-11.0.0_r4android-11.0.0_r3android-11.0.0_r25android-11.0.0_r2android-11.0.0_r17android-11.0.0_r1android11-s1-releaseandroid11-release

Change-Id: I844f2e7744fc71755d0d995236270b57cec58c81

1 files changed, 16 insertions, 3 deletions

diff --git a/bpf_progs/clatd.c b/bpf_progs/clatd.c
index 102ecd96..e7586928 100644
--- a/bpf_progs/clatd.c
+++ b/bpf_progs/clatd.c
@@ -26,6 +26,10 @@
 #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 "netdbpf/bpf_shared.h"
@@ -226,9 +230,18 @@ int sched_cls_egress_clat_rawip(struct __sk_buff* skb) {
 
     switch (ip4->protocol) {
         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.
+        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_OK;
+            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_OK;
             break;
 
         default:  // do not know how to handle anything else