SukiSU-Ultra/website/docs/guide/how-to-integrate-for-non-gki.md

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:

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.

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.

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:

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

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

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

Finally, edit KernelSU/kernel/ksu.c and comment out enable_sucompat() then build your kernel again, KernelSU should works well.