much more finegrained bpf selinux privs for networking mainline
Goal is to gain a better handle on who has access to which maps
and to allow (with bpfloader changes to create in one directory
and move into the target directory) per-map selection of
selinux context, while still having reasonable defaults for stuff
pinned directly into the target location.
BPFFS (ie. /sys/fs/bpf) labelling is as follows:
subdirectory selinux context mainline usecase / usable by
/ fs_bpf no (*) core operating system (ie. platform)
/net_private fs_bpf_net_private yes, T+ network_stack
/net_shared fs_bpf_net_shared yes, T+ network_stack & system_server
/netd_readonly fs_bpf_netd_readonly yes, T+ network_stack & system_server & r/o to netd
/netd_shared fs_bpf_netd_shared yes, T+ network_stack & system_server & netd [**]
/tethering fs_bpf_tethering yes, S+ network_stack
/vendor fs_bpf_vendor no, T+ vendor
* initial support for bpf was added back in P,
but things worked differently back then with no bpfloader,
and instead netd doing stuff by hand,
bpfloader with pinning into /sys/fs/bpf was (I believe) added in Q
(and was definitely there in R)
** additionally bpf programs are accesible to netutils_wrapper
for use by iptables xt_bpf extensions
'mainline yes' currently means shipped by the com.android.tethering apex,
but this is really another case of bad naming, as it's really
the 'networking/connectivity/tethering' apex / mainline module.
Long term the plan is to merge a few other networking mainline modules
into it (and maybe give it a saner name...).
The reason for splitting net_private vs tethering is that:
S+ must support 4.9+ kernels and S era bpfloader v0.2+
T+ must support 4.14+ kernels and T beta3 era bpfloader v0.13+
The kernel affects the intelligence of the in-kernel bpf verifier
and the available bpf helper functions. Older kernels have
a tendency to reject programs that newer kernels allow.
/ && /vendor are not shipped via mainline, so only need to work
with the bpfloader that's part of the core os.
Bug: 218408035
Test: TreeHugger, manually on cuttlefish
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I674866ebe32aca4fc851818c1ffcbec12ac4f7d4
(cherry picked from commit 15715aea32b85c933778b97a46de6ccab42ca7fb)
diff --git a/private/system_server.te b/private/system_server.te
index c3be29c..4c3103c 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -1165,7 +1165,8 @@
# allow system_server to read the eBPF maps that stores the traffic stats information and update
# the map after snapshot is recorded, and to read, update and run the maps and programs used for
# time in state accounting
-allow system_server fs_bpf:file { read write };
+allow system_server { fs_bpf fs_bpf_net_shared fs_bpf_netd_readonly fs_bpf_netd_shared }:dir search;
+allow system_server { fs_bpf fs_bpf_net_shared fs_bpf_netd_readonly fs_bpf_netd_shared }:file { read write };
allow system_server bpfloader:bpf { map_read map_write prog_run };
# in order to invoke side effect of close() on such a socket calling synchronize_rcu()
allow system_server self:key_socket create;