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/bpfloader.te b/private/bpfloader.te
index d7b27b5..54cc916 100644
--- a/private/bpfloader.te
+++ b/private/bpfloader.te
@@ -6,9 +6,9 @@
allow bpfloader kmsg_device:chr_file w_file_perms;
# These permissions are required to pin ebpf maps & programs.
-allow bpfloader { fs_bpf fs_bpf_tethering fs_bpf_vendor }:dir { add_name create search write };
-allow bpfloader { fs_bpf fs_bpf_tethering fs_bpf_vendor }:file { create read setattr };
-allow { fs_bpf_tethering fs_bpf_vendor } fs_bpf:filesystem associate;
+allow bpfloader bpffs_type:dir { add_name create remove_name search write };
+allow bpfloader bpffs_type:file { create read rename setattr };
+allow { bpffs_type -fs_bpf } fs_bpf:filesystem associate;
# Allow bpfloader to create bpf maps and programs.
allow bpfloader self:bpf { map_create map_read map_write prog_load prog_run };
@@ -26,17 +26,21 @@
###
# TODO: get rid of init & vendor_init; Note: we don't care about getattr/mounton/search
-neverallow { domain -init -vendor_init } { fs_bpf fs_bpf_tethering fs_bpf_vendor }:dir { open read setattr };
-neverallow { domain -bpfloader } { fs_bpf fs_bpf_tethering fs_bpf_vendor }:dir { add_name create write };
-neverallow domain { fs_bpf fs_bpf_tethering fs_bpf_vendor }:dir ~{ add_name create getattr mounton open read search setattr write };
+neverallow { domain -init -vendor_init } bpffs_type:dir { open read setattr };
+neverallow { domain -bpfloader } bpffs_type:dir { add_name create remove_name write };
+neverallow domain bpffs_type:dir ~{ add_name create getattr mounton open read remove_name search setattr write };
# TODO: get rid of init & vendor_init
-neverallow { domain -bpfloader -init -vendor_init } { fs_bpf fs_bpf_tethering fs_bpf_vendor }:file { map open setattr };
-neverallow { domain -bpfloader } { fs_bpf fs_bpf_tethering fs_bpf_vendor }:file create;
-neverallow { domain -bpfloader -gpuservice -init -lmkd -mediaprovider_app -netd -netutils_wrapper -network_stack -system_server -vendor_init } { fs_bpf }:file read;
-neverallow { domain -bpfloader -gpuservice -init -lmkd -netd -netutils_wrapper -network_stack -system_server -vendor_init } { fs_bpf_tethering }:file read;
-neverallow { domain -bpfloader -gpuservice -netd -netutils_wrapper -network_stack -system_server } { fs_bpf fs_bpf_tethering }:file write;
-neverallow domain { fs_bpf fs_bpf_tethering }:file ~{ create map open read setattr write };
+neverallow { domain -bpfloader -init -vendor_init } bpffs_type:file { map open setattr };
+neverallow { domain -bpfloader } bpffs_type:file { create rename };
+neverallow { domain -bpfloader -gpuservice -init -lmkd -mediaprovider_app -netd -netutils_wrapper -system_server -vendor_init } fs_bpf:file read;
+neverallow { domain -bpfloader -init -network_stack -vendor_init } fs_bpf_net_private:file read;
+neverallow { domain -bpfloader -init -network_stack -system_server -vendor_init } fs_bpf_net_shared:file read;
+neverallow { domain -bpfloader -init -netd -network_stack -system_server -vendor_init } fs_bpf_netd_readonly:file read;
+neverallow { domain -bpfloader -init -netd -netutils_wrapper -network_stack -system_server -vendor_init } fs_bpf_netd_shared:file read;
+neverallow { domain -bpfloader -init -network_stack -vendor_init } fs_bpf_tethering:file read;
+neverallow { domain -bpfloader -gpuservice -netd -netutils_wrapper -network_stack -system_server } { bpffs_type -fs_bpf_vendor }:file write;
+neverallow domain bpffs_type:file ~{ create map open read rename setattr write };
neverallow { domain -bpfloader } *:bpf { map_create prog_load };