kernel: Add CONFIG_KSU_MANUAL_SU configuration

- Use random passphrase protection for manual su functionality

kernel/Makefile

@@ -8,7 +8,9 @@ kernelsu-objs += ksud.o
 kernelsu-objs += embed_ksud.o
 kernelsu-objs += kernel_compat.o
 kernelsu-objs += throne_comm.o
+ifeq ($(CONFIG_KSU_MANUAL_SU), y)
 kernelsu-objs += manual_su.o
+endif
 
 ifeq ($(CONFIG_KSU_TRACEPOINT_HOOK), y)
 kernelsu-objs += ksu_trace.o
@@ -114,6 +116,17 @@ else
 $(info -- KPM is disabled)
 endif
 
+ifeq ($(CONFIG_KSU_MANUAL_SU), y)
+KSU_PW_POOL := abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789
+KSU_PW_LEN  := $(shell awk 'BEGIN{srand(); print int(rand()*9)+8}')
+KSU_SU_PASSWORD := $(shell \
+    tr -dc '$(KSU_PW_POOL)' </dev/urandom | head -c $(KSU_PW_LEN))
+
+ccflags-y += -DKSU_SU_PASSWORD=\"$(KSU_SU_PASSWORD)\"
+
+$(info -- KSU manual-su password : $(KSU_SU_PASSWORD))
+endif
+
 # SELinux drivers check
 ifeq ($(shell grep -q "current_sid(void)" $(srctree)/security/selinux/include/objsec.h; echo $$?),0)
 ccflags-y += -DKSU_COMPAT_HAS_CURRENT_SID