# How to integrate KernelSU for non GKI kernel?

KernelSU can be integrate to non GKI kernel, and it is backported to 4.14 now, it is also possible to run on kernel below 4.14.

Since the fragmentization of non GKI kernels, we don't have a uniform way to build it, so we can not provide non GKI boot images. But you can build the kernel yourself with KernelSU integrated.

First, you should be able to build a bootable kernel from kernel source code, if the kernel is not open sourced, then it is difficult to run KernelSU for your device.

If you can build a bootable kernel, there are two ways to integrate KernelSU to the kernel source code:

1. Automatically with `kprobe`
2. Manully

## Integrate with kprobe

KernelSU use kprobe to do kernel hooks, if the *kprobe* runs well in your kernel, it is recommended to use this way.

First, add KernelSU to your kernel source tree:

```sh
curl -LSs "https://raw.githubusercontent.com/tiann/KernelSU/main/kernel/setup.sh" | bash -
```

Then, you should check if *kprobe* is enabled in your kernel config, if it is not, please add these configs to it:

```
CONFIG_KPROBES=y
CONFIG_HAVE_KPROBES=y
CONFIG_KPROBE_EVENTS=y
```

And build your kernel again, KernelSU should works well.

If you find that KPROBES is still not activated, you can try enabling `CONFIG_MODULES`. (If it still doesn't take effect, use `make menuconfig` to search for other dependencies of KPROBES)

But if you encounter a boot loop when integrated KernelSU, it is maybe *kprobe is broken in your kernel*, you should fix the kprobe bug or use the second way.

:::tip How to check if kprobe is broken？

comment out `ksu_enable_sucompat()` and `ksu_enable_ksud()` in `KernelSU/kernel/ksu.c`, if the device boots normally, then kprobe may be broken.
:::

## Manully modify the kernel source

If kprobe can not work in your kernel (maybe a upstream bug or kernel below 4.8), then you can try this way:

First, add KernelSU to your kernel source tree:

- Latest tag(stable)

```sh
curl -LSs "https://raw.githubusercontent.com/tiann/KernelSU/main/kernel/setup.sh" | bash -
```

- main branch(dev)

```sh
curl -LSs "https://raw.githubusercontent.com/tiann/KernelSU/main/kernel/setup.sh" | bash -s main
```

- Select tag(Such as v0.5.2)

```sh
curl -LSs "https://raw.githubusercontent.com/tiann/KernelSU/main/kernel/setup.sh" | bash -s v0.5.2
```

Then, add KernelSU calls to the kernel source, here is a patch to refer:

```diff
diff --git a/fs/exec.c b/fs/exec.c
index ac59664eaecf..bdd585e1d2cc 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1890,11 +1890,14 @@ static int __do_execve_file(int fd, struct filename *filename,
 	return retval;
 }
 
+extern int ksu_handle_execveat(int *fd, struct filename **filename_ptr, void *argv,
+			void *envp, int *flags);
 static int do_execveat_common(int fd, struct filename *filename,
 			      struct user_arg_ptr argv,
 			      struct user_arg_ptr envp,
 			      int flags)
 {
+	ksu_handle_execveat(&fd, &filename, &argv, &envp, &flags);
 	return __do_execve_file(fd, filename, argv, envp, flags, NULL);
 }
 
diff --git a/fs/open.c b/fs/open.c
index 05036d819197..965b84d486b8 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -348,6 +348,8 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 	return ksys_fallocate(fd, mode, offset, len);
 }
 
+extern int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
+			 int *flags);
 /*
  * access() needs to use the real uid/gid, not the effective uid/gid.
  * We do this by temporarily clearing all FS-related capabilities and
@@ -355,6 +357,7 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
  */
 long do_faccessat(int dfd, const char __user *filename, int mode)
 {
+	ksu_handle_faccessat(&dfd, &filename, &mode, NULL);
 	const struct cred *old_cred;
 	struct cred *override_cred;
 	struct path path;
diff --git a/fs/read_write.c b/fs/read_write.c
index 650fc7e0f3a6..55be193913b6 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -434,10 +434,14 @@ ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
 }
 EXPORT_SYMBOL(kernel_read);
 
+extern int ksu_handle_vfs_read(struct file **file_ptr, char __user **buf_ptr,
+			size_t *count_ptr, loff_t **pos);
 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 {
 	ssize_t ret;
 
+	ksu_handle_vfs_read(&file, &buf, &count, &pos);
+	
 	if (!(file->f_mode & FMODE_READ))
 		return -EBADF;
 	if (!(file->f_mode & FMODE_CAN_READ))
diff --git a/fs/stat.c b/fs/stat.c
index 376543199b5a..82adcef03ecc 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -148,6 +148,8 @@ int vfs_statx_fd(unsigned int fd, struct kstat *stat,
 }
 EXPORT_SYMBOL(vfs_statx_fd);
 
+extern int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags);
+
 /**
  * vfs_statx - Get basic and extra attributes by filename
  * @dfd: A file descriptor representing the base dir for a relative filename
@@ -170,6 +172,7 @@ int vfs_statx(int dfd, const char __user *filename, int flags,
 	int error = -EINVAL;
 	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
 
+	ksu_handle_stat(&dfd, &filename, &flags);
 	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
 		       AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
 		return -EINVAL;
```

You should found the four functions in kernel source:

1. do_faccessat, usually in `fs/open.c`
2. do_execveat_common, usually in `fs/exec.c`
3. vfs_read, usually in `fs/read_write.c`
4. vfs_statx, usually in `fs/stat.c`

If your kernel does not have the `vfs_statx`, use `vfs_fstatat` instead:

```diff
diff --git a/fs/stat.c b/fs/stat.c
index 068fdbcc9e26..5348b7bb9db2 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -87,6 +87,8 @@ int vfs_fstat(unsigned int fd, struct kstat *stat)
 }
 EXPORT_SYMBOL(vfs_fstat);
 
+extern int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags);
+
 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 		int flag)
 {
@@ -94,6 +96,8 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 	int error = -EINVAL;
 	unsigned int lookup_flags = 0;
 
+	ksu_handle_stat(&dfd, &filename, &flag);
+
 	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
 		      AT_EMPTY_PATH)) != 0)
 		goto out;
```

For kernels eariler than 4.17, if you cannot find `do_faccessat`, just go to the definition of the `faccessat` syscall and place the call there:

```diff
diff --git a/fs/open.c b/fs/open.c
index 2ff887661237..e758d7db7663 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -355,6 +355,9 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 	return error;
 }
 
+extern int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
+			        int *flags);
+
 /*
  * access() needs to use the real uid/gid, not the effective uid/gid.
  * We do this by temporarily clearing all FS-related capabilities and
@@ -370,6 +373,8 @@ SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 	int res;
 	unsigned int lookup_flags = LOOKUP_FOLLOW;
 
+	ksu_handle_faccessat(&dfd, &filename, &mode, NULL);
+
 	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
 		return -EINVAL;
```

To enable KernelSU's builtin SafeMode, You should also modify `input_handle_event` in `drivers/input/input.c`:

:::tip
It is strongly recommended to enable this feature, it is very helpful for recusing from bootloop!
:::

```diff
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 45306f9ef247..815091ebfca4 100755
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -367,10 +367,13 @@ static int input_get_disposition(struct input_dev *dev,
        return disposition;
 }

+extern int ksu_handle_input_handle_event(unsigned int *type, unsigned int *code, int *value);
+
 static void input_handle_event(struct input_dev *dev,
                               unsigned int type, unsigned int code, int value)
 {
        int disposition = input_get_disposition(dev, type, code, &value);
+       ksu_handle_input_handle_event(&type, &code, &value);

        if (disposition != INPUT_IGNORE_EVENT && type != EV_SYN)
                add_input_randomness(type, code, value);
```

Finally, build your kernel again, KernelSU should works well.
