kernel: guard functionality that requires kprobes

Since upstream is now making kprobes a requirement, we adapt this tree to still allow
building with manual hooks in an easier way. Furthermore, this also allows a user to
build with manual hooks even with kprobes enabled.

Offending commit:
	kernel: remove unused CONFIG guard becuase GKI kernel enable kprobe by default
	upstream: https://github.com/tiann/KernelSU/commit/500ff9b

Other changes:
	ksud.c, stop_input_hook(), short-circuit redundant logic left by this change.
	cherry pick from: https://github.com/backslashxx/KernelSU/commit/a3d3e93

Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>

kernel/Kconfig

@@ -9,6 +9,14 @@ config KSU
 	  To compile as a module, choose M here: the
 	  module will be called kernelsu.
 
+config KSU_WITH_KPROBES
+	bool "Use kprobes for kernelsu"
+	depends on KSU
+	depends on KPROBES
+	default y
+	help
+	  Disable if you use manual hooks.
+
 config KSU_DEBUG
 	bool "KernelSU debug mode"
 	depends on KSU

kernel/core_hook.c

@@ -968,7 +968,7 @@ void __init ksu_core_init(void)
 
 void ksu_core_exit(void)
 {
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	pr_info("ksu_core_kprobe_exit\n");
 	// we dont use this now
 	// ksu_kprobe_exit();

kernel/ksu.c

@@ -11,6 +11,10 @@
 #include "ksu.h"
 #include "throne_tracker.h"
 
+#ifdef MODULE
+#define CONFIG_KSU_WITH_KPROBES
+#endif
+
 static struct workqueue_struct *ksu_workqueue;
 
 bool ksu_queue_work(struct work_struct *work)
@@ -57,7 +61,7 @@ int __init kernelsu_init(void)
 
 	ksu_throne_tracker_init();
 
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	ksu_sucompat_init();
 	ksu_ksud_init();
 #else
@@ -80,7 +84,7 @@ void kernelsu_exit(void)
 
 	destroy_workqueue(ksu_workqueue);
 
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	ksu_ksud_exit();
 	ksu_sucompat_exit();
 #endif

kernel/ksud.c

@@ -54,7 +54,7 @@ static void stop_vfs_read_hook();
 static void stop_execve_hook();
 static void stop_input_hook();
 
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 static struct work_struct stop_vfs_read_work;
 static struct work_struct stop_execve_hook_work;
 static struct work_struct stop_input_hook_work;
@@ -157,7 +157,7 @@ int ksu_handle_execveat_ksud(int *fd, struct filename **filename_ptr,
 			     struct user_arg_ptr *argv,
 			     struct user_arg_ptr *envp, int *flags)
 {
-#ifndef CONFIG_KPROBES
+#ifndef CONFIG_KSU_WITH_KPROBES
 	if (!ksu_execveat_hook) {
 		return 0;
 	}
@@ -313,7 +313,7 @@ static ssize_t read_iter_proxy(struct kiocb *iocb, struct iov_iter *to)
 int ksu_handle_vfs_read(struct file **file_ptr, char __user **buf_ptr,
 			size_t *count_ptr, loff_t **pos)
 {
-#ifndef CONFIG_KPROBES
+#ifndef CONFIG_KSU_WITH_KPROBES
 	if (!ksu_vfs_read_hook) {
 		return 0;
 	}
@@ -426,7 +426,7 @@ static bool is_volumedown_enough(unsigned int count)
 int ksu_handle_input_handle_event(unsigned int *type, unsigned int *code,
 				  int *value)
 {
-#ifndef CONFIG_KPROBES
+#ifndef CONFIG_KSU_WITH_KPROBES
 	if (!ksu_input_hook) {
 		return 0;
 	}
@@ -468,7 +468,7 @@ bool ksu_is_safe_mode()
 	return false;
 }
 
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 
 // https://elixir.bootlin.com/linux/v5.10.158/source/fs/exec.c#L1864
 static int execve_handler_pre(struct kprobe *p, struct pt_regs *regs)
@@ -598,7 +598,7 @@ static void do_stop_input_hook(struct work_struct *work)
 
 static void stop_vfs_read_hook()
 {
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	bool ret = schedule_work(&stop_vfs_read_work);
 	pr_info("unregister vfs_read kprobe: %d!\n", ret);
 #else
@@ -609,7 +609,7 @@ static void stop_vfs_read_hook()
 
 static void stop_execve_hook()
 {
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	bool ret = schedule_work(&stop_execve_hook_work);
 	pr_info("unregister execve kprobe: %d!\n", ret);
 #else
@@ -620,15 +620,16 @@ static void stop_execve_hook()
 
 static void stop_input_hook()
 {
+#ifdef CONFIG_KSU_WITH_KPROBES
 	static bool input_hook_stopped = false;
 	if (input_hook_stopped) {
 		return;
 	}
 	input_hook_stopped = true;
-#ifdef CONFIG_KPROBES
 	bool ret = schedule_work(&stop_input_hook_work);
 	pr_info("unregister input kprobe: %d!\n", ret);
 #else
+	if (!ksu_input_hook) { return; }
 	ksu_input_hook = false;
 	pr_info("stop input_hook\n");
 #endif
@@ -637,7 +638,7 @@ static void stop_input_hook()
 // ksud: module support
 void ksu_ksud_init()
 {
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	int ret;
 
 	ret = register_kprobe(&execve_kp);
@@ -657,10 +658,10 @@ void ksu_ksud_init()
 
 void ksu_ksud_exit()
 {
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	unregister_kprobe(&execve_kp);
 	// this should be done before unregister vfs_read_kp
 	// unregister_kprobe(&vfs_read_kp);
 	unregister_kprobe(&input_event_kp);
 #endif
-}
+}

kernel/sucompat.c

@@ -198,7 +198,7 @@ int ksu_handle_devpts(struct inode *inode)
 	return 0;
 }
 
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 
 static int faccessat_handler_pre(struct kprobe *p, struct pt_regs *regs)
 {
@@ -277,7 +277,7 @@ static struct kprobe *su_kps[4];
 // sucompat: permited process can execute 'su' to gain root access.
 void ksu_sucompat_init()
 {
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	su_kps[0] = init_kprobe(SYS_EXECVE_SYMBOL, execve_handler_pre);
 	su_kps[1] = init_kprobe(SYS_FACCESSAT_SYMBOL, faccessat_handler_pre);
 	su_kps[2] = init_kprobe(SYS_NEWFSTATAT_SYMBOL, newfstatat_handler_pre);
@@ -287,7 +287,7 @@ void ksu_sucompat_init()
 
 void ksu_sucompat_exit()
 {
-#ifdef CONFIG_KPROBES
+#ifdef CONFIG_KSU_WITH_KPROBES
 	for (int i = 0; i < ARRAY_SIZE(su_kps); i++) {
 		destroy_kprobe(&su_kps[i]);
 	}