From bb02b12a692e022af13c7ff4daa67484159642c9 Mon Sep 17 00:00:00 2001
From: rsuntk <rsuntk@yukiprjkt.my.id>
Date: Wed, 25 Jun 2025 14:53:34 +0700
Subject: [PATCH] kernel: phase out devpts_hook

* Since it's interceptable from LSM Hook,
then we just need to remove ksu_handle_devpts and
make a decoy for it.

Signed-off-by: rsuntk <rsuntk@yukiprjkt.my.id>
---
 kernel/Makefile    | 14 --------------
 kernel/core_hook.c |  8 ++------
 kernel/sucompat.c  | 26 ++++++++++++++++++--------
 3 files changed, 20 insertions(+), 28 deletions(-)

diff --git a/kernel/Makefile b/kernel/Makefile
index a00a133d..ec2aee25 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -137,20 +137,6 @@ $(info -- KernelSU: SusFS: Adding 'int path_umount(struct path *path, int flags)
 endif
 endif
 
-# we have pts_unix98/devpts_get_priv hook compat !!
-KSU_HAS_DEVPTS_INODE := $(shell grep -q "ksu_handle_devpts" $(srctree)/fs/devpts/inode.c; echo $$?)
-KSU_HAS_PTS_UNIX98 := $(shell grep -q "ksu_handle_devpts" $(srctree)/drivers/tty/pty.c; echo $$?)
-
-# Codes:
-# - 0: Both of them exist (impossible)
-# - 1: Neither fs/devpts/inode.c or drivers/tty/pty.c have ksu_handle_devpts
-# - 2: Both of them did not exist
-$(eval KSU_DEVPTS_HANDLER_EXIST=$(shell expr $(KSU_HAS_DEVPTS_INODE) + $(KSU_HAS_PTS_UNIX98)))
-ifeq ($(KSU_DEVPTS_HANDLER_EXIST),1)
-$(info -- KernelSU: Kernel have devpts handler)
-ccflags-y += -DKSU_HAS_DEVPTS_HANDLER
-endif
-
 # Checks Samsung UH drivers
 ifeq ($(shell grep -q "CONFIG_KDP_CRED" $(srctree)/kernel/cred.c; echo $$?),0)
 ccflags-y += -DSAMSUNG_UH_DRIVER_EXIST
diff --git a/kernel/core_hook.c b/kernel/core_hook.c
index 6e57a140..2f824919 100644
--- a/kernel/core_hook.c
+++ b/kernel/core_hook.c
@@ -1400,27 +1400,23 @@ static int ksu_task_fix_setuid(struct cred *new, const struct cred *old,
 }
 
 #ifndef MODULE
-#ifndef KSU_HAS_DEVPTS_HANDLER
-extern int ksu_handle_devpts(struct inode *inode);
+extern int __ksu_handle_devpts(struct inode *inode);
 static int ksu_inode_permission(struct inode *inode, int mask)
 {
 	if (unlikely(inode->i_sb && inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)) {
 #ifdef CONFIG_KSU_DEBUG
 		pr_info("%s: devpts inode accessed with mask: %x\n", __func__, mask);
 #endif
-		ksu_handle_devpts(inode);
+		__ksu_handle_devpts(inode);
 	}
 	return 0;
 }
-#endif
 
 static struct security_hook_list ksu_hooks[] = {
 	LSM_HOOK_INIT(task_prctl, ksu_task_prctl),
 	LSM_HOOK_INIT(inode_rename, ksu_inode_rename),
 	LSM_HOOK_INIT(task_fix_setuid, ksu_task_fix_setuid),
-#ifndef KSU_HAS_DEVPTS_HANDLER
 	LSM_HOOK_INIT(inode_permission, ksu_inode_permission),
-#endif
 #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) ||	\
 	defined(CONFIG_IS_HW_HISI) ||	\
 	defined(CONFIG_KSU_ALLOWLIST_WORKAROUND)
diff --git a/kernel/sucompat.c b/kernel/sucompat.c
index f81ccce5..b9b8fa12 100644
--- a/kernel/sucompat.c
+++ b/kernel/sucompat.c
@@ -233,14 +233,8 @@ int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user,
 	return 0;
 }
 
-int ksu_handle_devpts(struct inode *inode)
+static int ksu_inline_handle_devpts(struct inode *inode)
 {
-#ifndef CONFIG_KSU_KPROBES_HOOK
-	if (!ksu_sucompat_hook_state) {
-		return 0;
-	}
-#endif
-
 	if (!current->mm) {
 		return 0;
 	}
@@ -269,6 +263,22 @@ int ksu_handle_devpts(struct inode *inode)
 	return 0;
 }
 
+int __ksu_handle_devpts(struct inode *inode)
+{
+#ifndef CONFIG_KSU_KPROBES_HOOK
+	if (!ksu_sucompat_hook_state) {
+		return 0;
+	}
+#endif
+	return ksu_inline_handle_devpts(inode);
+}
+
+// dead code, we are phasing out ksu_handle_devpts for LSM hooks.
+int __maybe_unused ksu_handle_devpts(struct inode *inode)
+{
+	return 0;
+}
+
 #ifdef CONFIG_KSU_KPROBES_HOOK
 
 static int faccessat_handler_pre(struct kprobe *p, struct pt_regs *regs)
@@ -315,7 +325,7 @@ static int pts_unix98_lookup_pre(struct kprobe *p, struct pt_regs *regs)
 	inode = (struct inode *)PT_REGS_PARM2(regs);
 #endif
 
-	return ksu_handle_devpts(inode);
+	return ksu_inline_handle_devpts(inode);
 }
 #else
 static struct kprobe *su_kps[5];