commit 95d85068a3ac59f1fedbe7cb600b11984e5c294f
author Maciej Żenczykowski <maze@google.com> Thu Feb 08 00:37:17 2024 +0000
committer Maciej Żenczykowski <maze@google.com> Wed Apr 24 18:03:30 2024 +0000
tree efb9c1ae6e93ea8f1e700928680778d77dc6d77e
parent bd50241d0383839b858d56aa917b7d394403ba8d

netd.c: BACKGROUND_MATCH bypass for 'lo' traffic

Bug: 324323427
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I376559423053cbec0940b98c86efacfff27c12a8

bpf_progs/netd.c

diff --git a/bpf_progs/netd.c b/bpf_progs/netd.c
index dfc7699..25837a9 100644
--- a/bpf_progs/netd.c
+++ b/bpf_progs/netd.c
@@ -407,6 +407,9 @@
 
     BpfConfig enabledRules = getConfig(UID_RULES_CONFIGURATION_KEY);
 
+    // BACKGROUND match does not apply to loopback traffic
+    if (skb->ifindex == 1) enabledRules &= ~BACKGROUND_MATCH;
+
     UidOwnerValue* uidEntry = bpf_uid_owner_map_lookup_elem(&uid);
     uint32_t uidRules = uidEntry ? uidEntry->rule : 0;
     uint32_t allowed_iif = uidEntry ? uidEntry->iif : 0;