kernel: Allow to re-enable sucompat

Author: tiann

kernel/sucompat.c

@@ -191,7 +191,7 @@ int ksu_handle_devpts(struct inode *inode)
 
 #ifdef CONFIG_KPROBES
 
-static int sys_faccessat_handler_pre(struct kprobe *p, struct pt_regs *regs)
+static int faccessat_handler_pre(struct kprobe *p, struct pt_regs *regs)
 {
 	struct pt_regs *real_regs = PT_REAL_REGS(regs);
 	int *dfd = (int *)&PT_REGS_PARM1(real_regs);
@@ -202,17 +202,18 @@ static int sys_faccessat_handler_pre(struct kprobe *p, struct pt_regs *regs)
 	return ksu_handle_faccessat(dfd, filename_user, mode, NULL);
 }
 
-static int sys_newfstatat_handler_pre(struct kprobe *p, struct pt_regs *regs)
+static int newfstatat_handler_pre(struct kprobe *p, struct pt_regs *regs)
 {
 	struct pt_regs *real_regs = PT_REAL_REGS(regs);
 	int *dfd = (int *)&PT_REGS_PARM1(real_regs);
-	const char __user **filename_user = (const char **)&PT_REGS_PARM2(real_regs);
+	const char __user **filename_user =
+		(const char **)&PT_REGS_PARM2(real_regs);
 	int *flags = (int *)&PT_REGS_SYSCALL_PARM4(real_regs);
 
 	return ksu_handle_stat(dfd, filename_user, flags);
 }
 
-static int sys_execve_handler_pre(struct kprobe *p, struct pt_regs *regs)
+static int execve_handler_pre(struct kprobe *p, struct pt_regs *regs)
 {
 	struct pt_regs *real_regs = PT_REAL_REGS(regs);
 	const char __user **filename_user =
@@ -222,21 +223,6 @@ static int sys_execve_handler_pre(struct kprobe *p, struct pt_regs *regs)
 					  NULL);
 }
 
-static struct kprobe faccessat_kp = {
-	.symbol_name = SYS_FACCESSAT_SYMBOL,
-	.pre_handler = sys_faccessat_handler_pre,
-};
-
-static struct kprobe newfstatat_kp = {
-	.symbol_name = SYS_NEWFSTATAT_SYMBOL,
-	.pre_handler = sys_newfstatat_handler_pre,
-};
-
-static struct kprobe execve_kp = {
-	.symbol_name = SYS_EXECVE_SYMBOL,
-	.pre_handler = sys_execve_handler_pre,
-};
-
 static int pts_unix98_lookup_pre(struct kprobe *p, struct pt_regs *regs)
 {
 	struct inode *inode;
@@ -246,35 +232,56 @@ static int pts_unix98_lookup_pre(struct kprobe *p, struct pt_regs *regs)
 	return ksu_handle_devpts(inode);
 }
 
-static struct kprobe pts_unix98_lookup_kp = { .symbol_name =
-						      "pts_unix98_lookup",
-					      .pre_handler =
-						      pts_unix98_lookup_pre };
-
 #endif
 
+static struct kprobe *init_kprobe(const char *name,
+				  kprobe_pre_handler_t handler)
+{
+	struct kprobe *kp = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
+	if (!kp)
+		return NULL;
+	kp->symbol_name = name;
+	kp->pre_handler = handler;
+
+	int ret = register_kprobe(kp);
+	pr_info("sucompat: register_%s kprobe: %d\n", name, ret);
+	if (ret) {
+		kfree(kp);
+		return NULL;
+	}
+
+	return kp;
+}
+
+static void destroy_kprobe(struct kprobe **kp_ptr)
+{
+	struct kprobe *kp = *kp_ptr;
+	if (!kp)
+		return;
+	unregister_kprobe(kp);
+	synchronize_rcu();
+	kfree(kp);
+	*kp_ptr = NULL;
+}
+
+static struct kprobe *su_kps[4];
+
 // sucompat: permited process can execute 'su' to gain root access.
 void ksu_sucompat_init()
 {
 #ifdef CONFIG_KPROBES
-	int ret;
-	ret = register_kprobe(&execve_kp);
-	pr_info("sucompat: execve_kp: %d\n", ret);
-	ret = register_kprobe(&newfstatat_kp);
-	pr_info("sucompat: newfstatat_kp: %d\n", ret);
-	ret = register_kprobe(&faccessat_kp);
-	pr_info("sucompat: faccessat_kp: %d\n", ret);
-	ret = register_kprobe(&pts_unix98_lookup_kp);
-	pr_info("sucompat: devpts_kp: %d\n", ret);
+	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);
+	su_kps[3] = init_kprobe("pts_unix98_lookup", pts_unix98_lookup_pre);
 #endif
 }
 
 void ksu_sucompat_exit()
 {
 #ifdef CONFIG_KPROBES
-	unregister_kprobe(&execve_kp);
-	unregister_kprobe(&newfstatat_kp);
-	unregister_kprobe(&faccessat_kp);
-	unregister_kprobe(&pts_unix98_lookup_kp);
+	for (int i = 0; i < ARRAY_SIZE(su_kps); i++) {
+		destroy_kprobe(&su_kps[i]);
+	}
 #endif
 }

manager/app/src/main/java/me/weishu/kernelsu/ui/screen/Settings.kt

@@ -181,7 +181,6 @@ fun SettingScreen(navigator: DestinationsNavigator) {
                     title = stringResource(id = R.string.settings_disable_su),
                     summary = stringResource(id = R.string.settings_disable_su_summary),
                     checked = isSuDisabled,
-                    enabled = !isSuDisabled // we can't re-enable su if it's disabled.
                 ) { checked ->
                     val shouldEnable = !checked
                     if (Natives.setSuEnabled(shouldEnable)) {
@@ -502,4 +501,4 @@ private fun TopBar(
 @Composable
 private fun SettingsPreview() {
     SettingScreen(EmptyDestinationsNavigator)
-}
+}