commit ccce4a3382baa020df17c03d650e54cbfb31fc7f
author Maciej Żenczykowski <maze@google.com> Sun Jul 17 01:28:38 2022 -0700
committer Maciej Żenczykowski <maze@google.com> Mon Jul 18 09:05:32 2022 -0700
tree 99c4e79d58ce3bb96856f61d40f4c14ba6b3f74c
parent e9e7741872fff9209f99b30668cabeaf648e6bee

offload/test bpf: support InProcessTethering

InProcessTethering runs as system_server (uid/gid AID_SYSTEM)
instead of as the network_stack (uid/gid AID_NETWORK_STACK).

Additionally only the network_stack has access to the default
selinux context of /sys/fs/bpf/tethering, which is fs_bpf_tethering,
so we need to use 'fs_bpf_net_shared' instead.

Bug: 190523685
Bug: 236925089
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ibb6ae255dcd8a8e8049be112055f60c3b2cf7df0

bpf_progs/test.c

diff --git a/bpf_progs/test.c b/bpf_progs/test.c
index e22fe2a..d42205f 100644
--- a/bpf_progs/test.c
+++ b/bpf_progs/test.c
@@ -29,18 +29,28 @@
 #define BPFLOADER_MAX_VER BPFLOADER_OBJ_AT_VER_VERSION
 #endif /* BTF */
 
+// Warning: values other than AID_ROOT don't work for map uid on BpfLoader < v0.21
+#define TETHERING_UID AID_ROOT
+
+#ifdef INPROCESS
+#define DEFAULT_BPF_MAP_SELINUX_CONTEXT "fs_bpf_net_shared"
+#define DEFAULT_BPF_PROG_SELINUX_CONTEXT "fs_bpf_net_shared"
+#define TETHERING_GID AID_SYSTEM
+#else
+#define TETHERING_GID AID_NETWORK_STACK
+#endif
+
 #include "bpf_helpers.h"
 #include "bpf_net_helpers.h"
 #include "bpf_tethering.h"
 
 // Used only by TetheringPrivilegedTests, not by production code.
 DEFINE_BPF_MAP_GRW(tether_downstream6_map, HASH, TetherDownstream6Key, Tether6Value, 16,
-                   AID_NETWORK_STACK)
+                   TETHERING_GID)
 // Used only by BpfBitmapTest, not by production code.
-DEFINE_BPF_MAP_GRW(bitmap, ARRAY, int, uint64_t, 2,
-                   AID_NETWORK_STACK)
+DEFINE_BPF_MAP_GRW(bitmap, ARRAY, int, uint64_t, 2, TETHERING_GID)
 
-DEFINE_BPF_PROG_KVER("xdp/drop_ipv4_udp_ether", AID_ROOT, AID_NETWORK_STACK,
+DEFINE_BPF_PROG_KVER("xdp/drop_ipv4_udp_ether", TETHERING_UID, TETHERING_GID,
                       xdp_test, KVER(5, 9, 0))
 (struct xdp_md *ctx) {
     void *data = (void *)(long)ctx->data;