Allow tracing service to access kallsyms on userdebug
This CL allows the traced_probes service to temporarily
lower kptr_restrict and read /proc/kallsyms.
This is allowed only on userdebug/eng builds.
The lowering of kptr_restrict is done via an init
property because the kernel checks that the kptr_restrict
writer is CAP_SYS_ADMIN, regardless of the /proc file ACLs [1].
[1] https://github.com/torvalds/linux/blob/4cbffc461ec91287c4cb1d0e27b01b988d0b8fba/kernel/sysctl.c#L2254
Bug: 136133013
Design doc: go/perfetto-kallsyms
Test: perfetto_integrationtests --gtest_filter=PerfettoTest.KernelAddressSymbolization in r.android.com/1454882
Change-Id: Ic06e7a9a74c0f3e42fa63f7f41decc385c9fea2c
diff --git a/private/genfs_contexts b/private/genfs_contexts
index 136da2b..1b22725 100644
--- a/private/genfs_contexts
+++ b/private/genfs_contexts
@@ -10,6 +10,7 @@
genfscon proc /filesystems u:object_r:proc_filesystems:s0
genfscon proc /interrupts u:object_r:proc_interrupts:s0
genfscon proc /iomem u:object_r:proc_iomem:s0
+genfscon proc /kallsyms u:object_r:proc_kallsyms:s0
genfscon proc /keys u:object_r:proc_keys:s0
genfscon proc /kmsg u:object_r:proc_kmsg:s0
genfscon proc /loadavg u:object_r:proc_loadavg:s0