From 3f0f34e5b1c78833ebfa8a4ebc965cdc65c31438 Mon Sep 17 00:00:00 2001
From: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>
Date: Sat, 27 Sep 2025 23:59:21 +0800
Subject: [PATCH] kernel: core_hook: add support for KernelNoSU
 ([#270](https://github.com/SukiSU-Ultra/SukiSU-Ultra/issues/270))

reorder ksu_handle_prctl checks a bit to allow non-manager to use CMD 15
this allows us to piggyback a small su to KernelSU's permission system after
disabling kernel sucompat

from:
Relax prctl perm check
- https://github.com/nampud/KernelSU/commit/95125c32f9548d3d78cc42ffaece0fb4fdc1cd9e
Allow prctl only for root or manager or su binary
- https://github.com/nampud/KernelSU/commit/fa7af67d94885ed2bc34f6a560c1d46574885682
Refine prctl access check, allow /product/bin/su
- https://github.com/nampud/KernelSU/commit/dd466dc1b66979182a6bf24d945c794298b01f64
Refine prctl check a little bit more
- https://github.com/nampud/KernelSU/commit/e7c5b24efa30e5caef2c024b8ce523e7ecfb04a9

Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
Co-authored-by: nampud <nampud@users.noreply.github.com>
---
 kernel/core_hook.c | 73 ++++++++++++++++++++++++++--------------------
 1 file changed, 42 insertions(+), 31 deletions(-)

diff --git a/kernel/core_hook.c b/kernel/core_hook.c
index 87fedf13..45b85144 100644
--- a/kernel/core_hook.c
+++ b/kernel/core_hook.c
@@ -353,6 +353,16 @@ static inline void nuke_ext4_sysfs(void)
 }
 #endif
 
+static bool is_system_bin_su()
+{
+	// YES in_execve becomes 0 when it succeeds.
+	if (!current->mm || current->in_execve) 
+		return false;
+
+	// quick af check
+	return (current->mm->exe_file && !strcmp(current->mm->exe_file->f_path.dentry->d_name.name, "su"));
+}
+
 static void init_uid_scanner(void)
 {
 	ksu_uid_init();
@@ -388,7 +398,8 @@ int ksu_handle_prctl(int option, unsigned long arg2, unsigned long arg3,
 	bool from_root = 0 == current_uid().val;
 	bool from_manager = is_manager();
 
-	if (!from_root && !from_manager) {
+	if (!from_root && !from_manager 
+		&& !(is_allow_su() && is_system_bin_su())) {
 		// only root or manager can access this interface
 		return 0;
 	}
@@ -621,6 +632,36 @@ int ksu_handle_prctl(int option, unsigned long arg2, unsigned long arg3,
 	}
 #endif
 
+	if (arg2 == CMD_ENABLE_SU) {
+		bool enabled = (arg3 != 0);
+		if (enabled == ksu_su_compat_enabled) {
+			pr_info("cmd enable su but no need to change.\n");
+			if (copy_to_user(result, &reply_ok, sizeof(reply_ok))) {// return the reply_ok directly
+				pr_err("prctl reply error, cmd: %lu\n", arg2);
+			}
+			return 0;
+		}
+
+		if (enabled) {
+#ifdef CONFIG_KSU_SUSFS_SUS_SU
+			// We disable all sus_su hook whenever user toggle on su_kps
+			susfs_is_sus_su_hooks_enabled = false;
+			ksu_devpts_hook = false;
+			susfs_sus_su_working_mode = SUS_SU_DISABLED;
+#endif
+			ksu_sucompat_init();
+		} else {
+			ksu_sucompat_exit();
+		}
+		ksu_su_compat_enabled = enabled;
+
+		if (copy_to_user(result, &reply_ok, sizeof(reply_ok))) {
+			pr_err("prctl reply error, cmd: %lu\n", arg2);
+		}
+
+		return 0;
+	}
+
 	// Check if kpm is enabled
 	if (arg2 == CMD_ENABLE_KPM) {
     	bool KPM_Enabled = IS_ENABLED(CONFIG_KPM);
@@ -1089,36 +1130,6 @@ int ksu_handle_prctl(int option, unsigned long arg2, unsigned long arg3,
 		return 0;
 	}
 
-	if (arg2 == CMD_ENABLE_SU) {
-		bool enabled = (arg3 != 0);
-		if (enabled == ksu_su_compat_enabled) {
-			pr_info("cmd enable su but no need to change.\n");
-			if (copy_to_user(result, &reply_ok, sizeof(reply_ok))) {// return the reply_ok directly
-				pr_err("prctl reply error, cmd: %lu\n", arg2);
-			}
-			return 0;
-		}
-
-		if (enabled) {
-#ifdef CONFIG_KSU_SUSFS_SUS_SU
-			// We disable all sus_su hook whenever user toggle on su_kps
-			susfs_is_sus_su_hooks_enabled = false;
-			ksu_devpts_hook = false;
-			susfs_sus_su_working_mode = SUS_SU_DISABLED;
-#endif
-			ksu_sucompat_init();
-		} else {
-			ksu_sucompat_exit();
-		}
-		ksu_su_compat_enabled = enabled;
-
-		if (copy_to_user(result, &reply_ok, sizeof(reply_ok))) {
-			pr_err("prctl reply error, cmd: %lu\n", arg2);
-		}
-
-		return 0;
-	}
-
 	// UID Scanner control command
 	if (arg2 == CMD_ENABLE_UID_SCANNER) {
 		if (arg3 == 0) {