kernel: sucompat: sucompat toggle support for non-kp (tiann#2506)

kernel/selinux: fix pointer mismatch with 32-bit ksud on 64-bit kernels
Since KernelSU Manager can now be built for 32-bit, theres this problematic
setup where userspace is 32-bit (armeabi-v7a) and kernel is 64bit (aarch64).

On 64-bit kernels with CONFIG_COMPAT=y, 32-bit userspace passes 32-bit pointers.
These values are interpreted as 64-bit pointers without proper casting and that
results in invalid or near-null memory access.

This patch adds proper compat-mode handling with the ff changes:
- introduce a dedicated struct (`sepol_compat_data`) using u32 fields
- use `compat_ptr()` to safely convert 32-bit user pointers to kernel pointers
- adding a runtime `ksu_is_compat` flag to dynamically select between struct layouts

This prevents a near-null pointer dereference when handling SELinux
policy updates from 32-bit ksud in a 64-bit kernel.

Truth table:

kernel 32 + ksud 32, struct is u32, no compat_ptr
kernel 64 + ksud 32, struct is u32, yes compat_ptr
kernel 64 + ksud 64, struct is u64, no compat_ptr

Preprocessor check

64BIT=y COMPAT=y: define both structs, select dynamically
64BIT=y COMPAT=n: struct u64
64BIT=n: struct u32

kernel/throne_tracker: we just uninstalled the manager, stop looking for it
When the manager UID disappears from packages.list, we correctly
invalidate it — good. But, in the very next breath, we start scanning
/data/app hoping to find it again?

This event is just unnecessary I/O, exactly when we should be doing less.
Apparently this causes hangups and stuckups which is REALLY noticeable
on Ultra-Legacy devices.

Skip the scan — we’ll catch the reinstall next time packages.list updates.

This is done like how vfs_read_hook, input_hook and execve_hook is disabled.
While this is not exactly the same thing, this CAN achieve the same results.
The complete disabling of all KernelSU hooks.

While this is likely unneeded, It keeps feature parity to non-kprobe builds.

adapted from upstream:
	kernel: Allow to re-enable sucompat - 4593ae81c7

Rejected: https://github.com/tiann/KernelSU/pull/2506

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

kernel/ksud.c

@@ -68,6 +68,10 @@ u32 ksu_devpts_sid;
 // Detect whether it is on or not
 static bool is_boot_phase = true;
 
+#ifdef CONFIG_COMPAT
+bool ksu_is_compat __read_mostly = false;
+#endif
+
 void ksu_on_post_fs_data(void)
 {
     static bool done = false;
@@ -111,6 +115,7 @@ static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
         if (get_user(compat, argv.ptr.compat + nr))
             return ERR_PTR(-EFAULT);
 
+        ksu_is_compat = true;
         return compat_ptr(compat);
     }
 #endif

kernel/selinux/rules.c

@@ -157,17 +157,45 @@ void ksu_apply_kernelsu_rules()
 #define CMD_TYPE_CHANGE 8
 #define CMD_GENFSCON 9
 
+#ifdef CONFIG_64BIT
 struct sepol_data {
 	u32 cmd;
 	u32 subcmd;
-	char __user *sepol1;
+	u64 field_sepol1;
-	char __user *sepol2;
+	u64 field_sepol2;
-	char __user *sepol3;
+	u64 field_sepol3;
-	char __user *sepol4;
+	u64 field_sepol4;
-	char __user *sepol5;
+	u64 field_sepol5;
-	char __user *sepol6;
+	u64 field_sepol6;
-	char __user *sepol7;
+	u64 field_sepol7;
 };
+#ifdef CONFIG_COMPAT
+extern bool ksu_is_compat __read_mostly;
+struct sepol_compat_data {
+	u32 cmd;
+	u32 subcmd;
+	u32 field_sepol1;
+	u32 field_sepol2;
+	u32 field_sepol3;
+	u32 field_sepol4;
+	u32 field_sepol5;
+	u32 field_sepol6;
+	u32 field_sepol7;
+};
+#endif // CONFIG_COMPAT
+#else
+struct sepol_data {
+	u32 cmd;
+	u32 subcmd;
+	u32 field_sepol1;
+	u32 field_sepol2;
+	u32 field_sepol3;
+	u32 field_sepol4;
+	u32 field_sepol5;
+	u32 field_sepol6;
+	u32 field_sepol7;
+};
+#endif // CONFIG_64BIT
 
 static int get_object(char *buf, char __user *user_object, size_t buf_sz,
 		      char **object)
@@ -212,14 +240,61 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 		pr_info("SELinux permissive or disabled when handle policy!\n");
 	}
 
+	u32 cmd, subcmd;
+	char __user *sepol1, *sepol2, *sepol3, *sepol4, *sepol5, *sepol6, *sepol7;
+
+#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
+	if (unlikely(ksu_is_compat)) {
+		struct sepol_compat_data compat_data;
+		if (copy_from_user(&compat_data, arg4, sizeof(struct sepol_compat_data))) {
+			pr_err("sepol: copy sepol_data failed.\n");
+			return -1;
+		}
+		sepol1 = compat_ptr(compat_data.field_sepol1);
+		sepol2 = compat_ptr(compat_data.field_sepol2);
+		sepol3 = compat_ptr(compat_data.field_sepol3);
+		sepol4 = compat_ptr(compat_data.field_sepol4);
+		sepol5 = compat_ptr(compat_data.field_sepol5);
+		sepol6 = compat_ptr(compat_data.field_sepol6);
+		sepol7 = compat_ptr(compat_data.field_sepol7);
+		cmd = compat_data.cmd;
+		subcmd = compat_data.subcmd;
+	} else {
+		struct sepol_data data;
+		if (copy_from_user(&data, arg4, sizeof(struct sepol_data))) {
+			pr_err("sepol: copy sepol_data failed.\n");
+			return -1;
+		}
+		sepol1 = data.field_sepol1;
+		sepol2 = data.field_sepol2;
+		sepol3 = data.field_sepol3;
+		sepol4 = data.field_sepol4;
+		sepol5 = data.field_sepol5;
+		sepol6 = data.field_sepol6;
+		sepol7 = data.field_sepol7;
+		cmd = data.cmd;
+		subcmd = data.subcmd;
+	}
+#else 
+	// basically for full native, say (64BIT=y COMPAT=n) || (64BIT=n)
+
 	struct sepol_data data;
 	if (copy_from_user(&data, arg4, sizeof(struct sepol_data))) {
 		pr_err("sepol: copy sepol_data failed.\n");
 		return -1;
 	}
 
-	u32 cmd = data.cmd;
+
-	u32 subcmd = data.subcmd;
+	sepol1 = data.field_sepol1;
+	sepol2 = data.field_sepol2;
+	sepol3 = data.field_sepol3;
+	sepol4 = data.field_sepol4;
+	sepol5 = data.field_sepol5;
+	sepol6 = data.field_sepol6;
+	sepol7 = data.field_sepol7;
+	cmd = data.cmd;
+	subcmd = data.subcmd;
+#endif
 
 	rcu_read_lock();
 
@@ -233,22 +308,22 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 		char perm_buf[MAX_SEPOL_LEN];
 
 		char *s, *t, *c, *p;
-		if (get_object(src_buf, data.sepol1, sizeof(src_buf), &s) < 0) {
+		if (get_object(src_buf, sepol1, sizeof(src_buf), &s) < 0) {
 			pr_err("sepol: copy src failed.\n");
 			goto exit;
 		}
 
-		if (get_object(tgt_buf, data.sepol2, sizeof(tgt_buf), &t) < 0) {
+		if (get_object(tgt_buf, sepol2, sizeof(tgt_buf), &t) < 0) {
 			pr_err("sepol: copy tgt failed.\n");
 			goto exit;
 		}
 
-		if (get_object(cls_buf, data.sepol3, sizeof(cls_buf), &c) < 0) {
+		if (get_object(cls_buf, sepol3, sizeof(cls_buf), &c) < 0) {
 			pr_err("sepol: copy cls failed.\n");
 			goto exit;
 		}
 
-		if (get_object(perm_buf, data.sepol4, sizeof(perm_buf), &p) <
+		if (get_object(perm_buf, sepol4, sizeof(perm_buf), &p) <
 		    0) {
 			pr_err("sepol: copy perm failed.\n");
 			goto exit;
@@ -278,24 +353,24 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 		char perm_set[MAX_SEPOL_LEN];
 
 		char *s, *t, *c;
-		if (get_object(src_buf, data.sepol1, sizeof(src_buf), &s) < 0) {
+		if (get_object(src_buf, sepol1, sizeof(src_buf), &s) < 0) {
 			pr_err("sepol: copy src failed.\n");
 			goto exit;
 		}
-		if (get_object(tgt_buf, data.sepol2, sizeof(tgt_buf), &t) < 0) {
+		if (get_object(tgt_buf, sepol2, sizeof(tgt_buf), &t) < 0) {
 			pr_err("sepol: copy tgt failed.\n");
 			goto exit;
 		}
-		if (get_object(cls_buf, data.sepol3, sizeof(cls_buf), &c) < 0) {
+		if (get_object(cls_buf, sepol3, sizeof(cls_buf), &c) < 0) {
 			pr_err("sepol: copy cls failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(operation, data.sepol4,
+		if (strncpy_from_user(operation, sepol4,
 				      sizeof(operation)) < 0) {
 			pr_err("sepol: copy operation failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(perm_set, data.sepol5, sizeof(perm_set)) <
+		if (strncpy_from_user(perm_set, sepol5, sizeof(perm_set)) <
 		    0) {
 			pr_err("sepol: copy perm_set failed.\n");
 			goto exit;
@@ -315,7 +390,7 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 	} else if (cmd == CMD_TYPE_STATE) {
 		char src[MAX_SEPOL_LEN];
 
-		if (strncpy_from_user(src, data.sepol1, sizeof(src)) < 0) {
+		if (strncpy_from_user(src, sepol1, sizeof(src)) < 0) {
 			pr_err("sepol: copy src failed.\n");
 			goto exit;
 		}
@@ -335,11 +410,11 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 		char type[MAX_SEPOL_LEN];
 		char attr[MAX_SEPOL_LEN];
 
-		if (strncpy_from_user(type, data.sepol1, sizeof(type)) < 0) {
+		if (strncpy_from_user(type, sepol1, sizeof(type)) < 0) {
 			pr_err("sepol: copy type failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(attr, data.sepol2, sizeof(attr)) < 0) {
+		if (strncpy_from_user(attr, sepol2, sizeof(attr)) < 0) {
 			pr_err("sepol: copy attr failed.\n");
 			goto exit;
 		}
@@ -359,7 +434,7 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 	} else if (cmd == CMD_ATTR) {
 		char attr[MAX_SEPOL_LEN];
 
-		if (strncpy_from_user(attr, data.sepol1, sizeof(attr)) < 0) {
+		if (strncpy_from_user(attr, sepol1, sizeof(attr)) < 0) {
 			pr_err("sepol: copy attr failed.\n");
 			goto exit;
 		}
@@ -376,28 +451,28 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 		char default_type[MAX_SEPOL_LEN];
 		char object[MAX_SEPOL_LEN];
 
-		if (strncpy_from_user(src, data.sepol1, sizeof(src)) < 0) {
+		if (strncpy_from_user(src, sepol1, sizeof(src)) < 0) {
 			pr_err("sepol: copy src failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(tgt, data.sepol2, sizeof(tgt)) < 0) {
+		if (strncpy_from_user(tgt, sepol2, sizeof(tgt)) < 0) {
 			pr_err("sepol: copy tgt failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(cls, data.sepol3, sizeof(cls)) < 0) {
+		if (strncpy_from_user(cls, sepol3, sizeof(cls)) < 0) {
 			pr_err("sepol: copy cls failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(default_type, data.sepol4,
+		if (strncpy_from_user(default_type, sepol4,
 				      sizeof(default_type)) < 0) {
 			pr_err("sepol: copy default_type failed.\n");
 			goto exit;
 		}
 		char *real_object;
-		if (data.sepol5 == NULL) {
+		if (sepol5 == NULL) {
 			real_object = NULL;
 		} else {
-			if (strncpy_from_user(object, data.sepol5,
+			if (strncpy_from_user(object, sepol5,
 					      sizeof(object)) < 0) {
 				pr_err("sepol: copy object failed.\n");
 				goto exit;
@@ -416,19 +491,19 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 		char cls[MAX_SEPOL_LEN];
 		char default_type[MAX_SEPOL_LEN];
 
-		if (strncpy_from_user(src, data.sepol1, sizeof(src)) < 0) {
+		if (strncpy_from_user(src, sepol1, sizeof(src)) < 0) {
 			pr_err("sepol: copy src failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(tgt, data.sepol2, sizeof(tgt)) < 0) {
+		if (strncpy_from_user(tgt, sepol2, sizeof(tgt)) < 0) {
 			pr_err("sepol: copy tgt failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(cls, data.sepol3, sizeof(cls)) < 0) {
+		if (strncpy_from_user(cls, sepol3, sizeof(cls)) < 0) {
 			pr_err("sepol: copy cls failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(default_type, data.sepol4,
+		if (strncpy_from_user(default_type, sepol4,
 				      sizeof(default_type)) < 0) {
 			pr_err("sepol: copy default_type failed.\n");
 			goto exit;
@@ -449,15 +524,15 @@ int ksu_handle_sepolicy(unsigned long arg3, void __user *arg4)
 		char name[MAX_SEPOL_LEN];
 		char path[MAX_SEPOL_LEN];
 		char context[MAX_SEPOL_LEN];
-		if (strncpy_from_user(name, data.sepol1, sizeof(name)) < 0) {
+		if (strncpy_from_user(name, sepol1, sizeof(name)) < 0) {
 			pr_err("sepol: copy name failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(path, data.sepol2, sizeof(path)) < 0) {
+		if (strncpy_from_user(path, sepol2, sizeof(path)) < 0) {
 			pr_err("sepol: copy path failed.\n");
 			goto exit;
 		}
-		if (strncpy_from_user(context, data.sepol3, sizeof(context)) <
+		if (strncpy_from_user(context, sepol3, sizeof(context)) <
 		    0) {
 			pr_err("sepol: copy context failed.\n");
 			goto exit;

kernel/sucompat.c

@@ -37,6 +37,10 @@ bool ksu_devpts_hook __read_mostly = true;
 
 extern void ksu_escape_to_root();
 
+#ifndef CONFIG_KSU_HOOK_KPROBES
+static bool ksu_sucompat_non_kp __read_mostly = true;
+#endif
+
 static void __user *userspace_stack_buffer(const void *d, size_t len)
 {
 	/* To avoid having to mmap a page in userspace, just write below the stack
@@ -63,6 +67,12 @@ int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
 {
 	const char su[] = SU_PATH;
 
+#ifndef CONFIG_KSU_HOOK_KPROBES
+	if (!ksu_sucompat_non_kp) {
+ 		return 0;
+ 	}
+#endif
+
 #ifndef CONFIG_KSU_HOOK_KPROBES
 	if (!ksu_faccessat_hook) {
 		return 0;
@@ -114,6 +124,12 @@ int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags)
 	// const char sh[] = SH_PATH;
 	const char su[] = SU_PATH;
 
+#ifndef CONFIG_KSU_HOOK_KPROBES
+	if (!ksu_sucompat_non_kp) {
+ 		return 0;
+ 	}
+#endif
+
 #ifndef CONFIG_KSU_HOOK_KPROBES
 	if (!ksu_stat_hook){
 		return 0;
@@ -160,6 +176,13 @@ int ksu_handle_execveat_sucompat(int *fd, struct filename **filename_ptr, void *
 	struct filename *filename;
     const char su[] = SU_PATH;
     const char ksud[] = KSUD_PATH;
+
+#ifndef CONFIG_KSU_HOOK_KPROBES
+	if (!ksu_sucompat_non_kp) {
+ 		return 0;
+ 	}
+#endif
+
 #ifndef CONFIG_KSU_HOOK_KPROBES
 	if (!ksu_execveat_sucompat_hook) {
 		return 0;
@@ -195,6 +218,13 @@ int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user, void
 	const char su[] = SU_PATH;
 	char path[sizeof(su) + 1];
 
+
+#ifndef CONFIG_KSU_HOOK_KPROBES
+	if (!ksu_sucompat_non_kp){
+ 		return 0;
+ 	}
+#endif
+
 #ifndef CONFIG_KSU_HOOK_KPROBES
 	if (!ksu_execve_sucompat_hook) {
 		return 0;
@@ -350,6 +380,7 @@ void ksu_sucompat_init()
 	ksu_execve_sucompat_hook = true;
 	ksu_execveat_sucompat_hook = true;
 	ksu_devpts_hook = true;
+	ksu_sucompat_non_kp = true;
 	pr_info("ksu_sucompat_init: hooks enabled: execve/execveat_su, faccessat, stat, devpts\n");
 #endif
 }
@@ -367,6 +398,7 @@ void ksu_sucompat_exit()
 	ksu_execve_sucompat_hook = false;
 	ksu_execveat_sucompat_hook = false;
 	ksu_devpts_hook = false;
+	ksu_sucompat_non_kp = false;
 	pr_info("ksu_sucompat_exit: hooks disabled: execve/execveat_su, faccessat, stat, devpts\n");
 #endif
 }

kernel/throne_tracker.c

@@ -361,12 +361,14 @@ void ksu_track_throne()
 		if (ksu_is_manager_uid_valid()) {
 			pr_info("manager is uninstalled, invalidate it!\n");
 			ksu_invalidate_manager_uid();
+			goto prune;
 		}
 		pr_info("Searching manager...\n");
 		search_manager("/data/app", 2, &uid_list);
 		pr_info("Search manager finished\n");
 	}
 	
+prune:
 	// then prune the allowlist
 	ksu_prune_allowlist(is_uid_exist, &uid_list);
 out: