384 lines
12 KiB
Markdown
384 lines
12 KiB
Markdown
# How to integrate KernelSU for non GKI kernels?
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KernelSU can be integrated into non GKI kernels, and was backported to 4.14 and below.
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Due to the fragmentization of non GKI kernels, we do not 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.
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First, you should be able to build a bootable kernel from kernel source code. If the kernel is not open source, then it is difficult to run KernelSU for your device.
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If you can build a bootable kernel, there are two ways to integrate KernelSU to the kernel source code:
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1. Automatically with `kprobe`
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2. Manually
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## Integrate with kprobe
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KernelSU uses kprobe to do kernel hooks, if the *kprobe* runs well in your kernel, it is recommended to use this way.
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First, add KernelSU to your kernel source tree:
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```sh
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curl -LSs "https://raw.githubusercontent.com/tiann/KernelSU/main/kernel/setup.sh" | bash -
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```
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Then, you should check if *kprobe* is enabled in your kernel config, if it is not, please add these configs to it:
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```
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CONFIG_KPROBES=y
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CONFIG_HAVE_KPROBES=y
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CONFIG_KPROBE_EVENTS=y
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```
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And build your kernel again, KernelSU should works well.
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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)
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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.
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:::tip How to check if kprobe is broken？
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comment out `ksu_enable_sucompat()` and `ksu_enable_ksud()` in `KernelSU/kernel/ksu.c`, if the device boots normally, then kprobe may be broken.
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:::
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:::info How to get module umount feature working on pre-GKI?
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If your kernel is older than 5.9, you should backport `path_umount` to `fs/namespace.c`. This is required to get module umount feature working. If you don't backport `path_umount`, module umount feature won't work. You can get more info on how to achieve this at the end of this page.
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:::
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## Manually modify the kernel source
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If kprobe does not work in your kernel (may be an upstream or kernel bug below 4.8), then you can try this way:
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First, add KernelSU to your kernel source tree:
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::: code-group
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```sh[Latest tag(stable)]
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curl -LSs "https://raw.githubusercontent.com/tiann/KernelSU/main/kernel/setup.sh" | bash -
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```
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```sh[ main branch(dev)]
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curl -LSs "https://raw.githubusercontent.com/tiann/KernelSU/main/kernel/setup.sh" | bash -s main
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```
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```sh[Select tag(Such as v0.5.2)]
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curl -LSs "https://raw.githubusercontent.com/tiann/KernelSU/main/kernel/setup.sh" | bash -s v0.5.2
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```
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:::
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Keep in mind that on some devices, your defconfig may be in `arch/arm64/configs` or in other cases `arch/arm64/configs/vendor/your_defconfig`. For example in your defconfig, Enable `CONFIG_KSU` with y to enable, or n to disable. Your path will be something like:
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`arch/arm64/configs/...`
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```
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# KernelSU
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CONFIG_KSU=y
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```
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Then, add KernelSU calls to the kernel source, here are some patches to refer:
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::: code-group
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```diff[exec.c]
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diff --git a/fs/exec.c b/fs/exec.c
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index ac59664eaecf..bdd585e1d2cc 100644
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--- a/fs/exec.c
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+++ b/fs/exec.c
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@@ -1890,11 +1890,14 @@ static int __do_execve_file(int fd, struct filename *filename,
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return retval;
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}
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+#ifdef CONFIG_KSU
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+extern bool ksu_execveat_hook __read_mostly;
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+extern int ksu_handle_execveat(int *fd, struct filename **filename_ptr, void *argv,
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+ void *envp, int *flags);
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+extern int ksu_handle_execveat_sucompat(int *fd, struct filename **filename_ptr,
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+ void *argv, void *envp, int *flags);
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+#endif
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static int do_execveat_common(int fd, struct filename *filename,
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struct user_arg_ptr argv,
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struct user_arg_ptr envp,
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int flags)
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{
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+ #ifdef CONFIG_KSU
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+ if (unlikely(ksu_execveat_hook))
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+ ksu_handle_execveat(&fd, &filename, &argv, &envp, &flags);
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+ else
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+ ksu_handle_execveat_sucompat(&fd, &filename, &argv, &envp, &flags);
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+ #endif
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return __do_execve_file(fd, filename, argv, envp, flags, NULL);
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}
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```
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```diff[open.c]
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diff --git a/fs/open.c b/fs/open.c
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index 05036d819197..965b84d486b8 100644
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--- a/fs/open.c
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+++ b/fs/open.c
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@@ -348,6 +348,8 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
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return ksys_fallocate(fd, mode, offset, len);
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}
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+#ifdef CONFIG_KSU
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+extern int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
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+ int *flags);
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+#endif
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/*
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* access() needs to use the real uid/gid, not the effective uid/gid.
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* We do this by temporarily clearing all FS-related capabilities and
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@@ -355,6 +357,7 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
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*/
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long do_faccessat(int dfd, const char __user *filename, int mode)
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{
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const struct cred *old_cred;
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struct cred *override_cred;
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struct path path;
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struct inode *inode;
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struct vfsmount *mnt;
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int res;
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unsigned int lookup_flags = LOOKUP_FOLLOW;
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+ #ifdef CONFIG_KSU
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+ ksu_handle_faccessat(&dfd, &filename, &mode, NULL);
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+ #endif
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if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
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return -EINVAL;
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```
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```diff[read_write.c]
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diff --git a/fs/read_write.c b/fs/read_write.c
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index 650fc7e0f3a6..55be193913b6 100644
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--- a/fs/read_write.c
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+++ b/fs/read_write.c
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@@ -434,10 +434,14 @@ ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
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}
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EXPORT_SYMBOL(kernel_read);
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+#ifdef CONFIG_KSU
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+extern bool ksu_vfs_read_hook __read_mostly;
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+extern int ksu_handle_vfs_read(struct file **file_ptr, char __user **buf_ptr,
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+ size_t *count_ptr, loff_t **pos);
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+#endif
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ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
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{
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ssize_t ret;
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+ #ifdef CONFIG_KSU
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+ if (unlikely(ksu_vfs_read_hook))
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+ ksu_handle_vfs_read(&file, &buf, &count, &pos);
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+ #endif
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+
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if (!(file->f_mode & FMODE_READ))
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return -EBADF;
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if (!(file->f_mode & FMODE_CAN_READ))
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```
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```diff[stat.c]
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diff --git a/fs/stat.c b/fs/stat.c
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index 376543199b5a..82adcef03ecc 100644
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--- a/fs/stat.c
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+++ b/fs/stat.c
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@@ -148,6 +148,8 @@ int vfs_statx_fd(unsigned int fd, struct kstat *stat,
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}
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EXPORT_SYMBOL(vfs_statx_fd);
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+#ifdef CONFIG_KSU
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+extern int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags);
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+#endif
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+
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/**
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* vfs_statx - Get basic and extra attributes by filename
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* @dfd: A file descriptor representing the base dir for a relative filename
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@@ -170,6 +172,7 @@ int vfs_statx(int dfd, const char __user *filename, int flags,
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int error = -EINVAL;
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unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
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+ #ifdef CONFIG_KSU
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+ ksu_handle_stat(&dfd, &filename, &flags);
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+ #endif
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if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
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AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
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return -EINVAL;
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```
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:::
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You should find the four functions in kernel source:
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1. do_faccessat, usually in `fs/open.c`
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2. do_execveat_common, usually in `fs/exec.c`
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3. vfs_read, usually in `fs/read_write.c`
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4. vfs_statx, usually in `fs/stat.c`
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If your kernel does not have the `vfs_statx`, use `vfs_fstatat` instead:
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```diff
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diff --git a/fs/stat.c b/fs/stat.c
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index 068fdbcc9e26..5348b7bb9db2 100644
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--- a/fs/stat.c
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+++ b/fs/stat.c
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@@ -87,6 +87,8 @@ int vfs_fstat(unsigned int fd, struct kstat *stat)
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}
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EXPORT_SYMBOL(vfs_fstat);
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+#ifdef CONFIG_KSU
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+extern int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags);
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+#endif
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int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
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int flag)
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{
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@@ -94,6 +96,8 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
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int error = -EINVAL;
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unsigned int lookup_flags = 0;
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+ #ifdef CONFIG_KSU
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+ ksu_handle_stat(&dfd, &filename, &flag);
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+ #endif
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+
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if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
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AT_EMPTY_PATH)) != 0)
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goto out;
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```
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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:
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```diff
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diff --git a/fs/open.c b/fs/open.c
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index 2ff887661237..e758d7db7663 100644
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--- a/fs/open.c
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+++ b/fs/open.c
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@@ -355,6 +355,9 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
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return error;
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}
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+#ifdef CONFIG_KSU
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+extern int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
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+ int *flags);
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+#endif
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+
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/*
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* access() needs to use the real uid/gid, not the effective uid/gid.
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* We do this by temporarily clearing all FS-related capabilities and
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@@ -370,6 +373,8 @@ SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
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int res;
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unsigned int lookup_flags = LOOKUP_FOLLOW;
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+ #ifdef CONFIG_KSU
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+ ksu_handle_faccessat(&dfd, &filename, &mode, NULL);
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+ #endif
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+
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if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
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return -EINVAL;
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```
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### Safe Mode
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To enable KernelSU's builtin SafeMode, You should also modify `input_handle_event` in `drivers/input/input.c`:
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:::tip
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It is strongly recommended to enable this feature, it is very helpful to prevent bootloops!
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:::
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```diff
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diff --git a/drivers/input/input.c b/drivers/input/input.c
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index 45306f9ef247..815091ebfca4 100755
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--- a/drivers/input/input.c
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+++ b/drivers/input/input.c
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@@ -367,10 +367,13 @@ static int input_get_disposition(struct input_dev *dev,
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return disposition;
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}
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+#ifdef CONFIG_KSU
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+extern bool ksu_input_hook __read_mostly;
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+extern int ksu_handle_input_handle_event(unsigned int *type, unsigned int *code, int *value);
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+#endif
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+
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static void input_handle_event(struct input_dev *dev,
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unsigned int type, unsigned int code, int value)
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{
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int disposition = input_get_disposition(dev, type, code, &value);
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+ #ifdef CONFIG_KSU
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+ if (unlikely(ksu_input_hook))
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+ ksu_handle_input_handle_event(&type, &code, &value);
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+ #endif
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if (disposition != INPUT_IGNORE_EVENT && type != EV_SYN)
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add_input_randomness(type, code, value);
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```
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:::info Entering safe mode accidiently?
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If you use manual integration and do not disable `CONFIG_KPROBES`, then the user may trigger safe mode by pressing the volume down button after booting! Therefore if using manual integration you need to disable `CONFIG_KPROBES`!
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:::
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### Failed to execute `pm` in terminal?
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You should modify `fs/devpts/inode.c`, reference:
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```diff
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diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
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index 32f6f1c68..d69d8eca2 100644
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--- a/fs/devpts/inode.c
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+++ b/fs/devpts/inode.c
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@@ -602,6 +602,8 @@ struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv)
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return dentry;
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}
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+extern int ksu_handle_devpts(struct inode*);
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+
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/**
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* devpts_get_priv -- get private data for a slave
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* @pts_inode: inode of the slave
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@@ -610,6 +612,7 @@ struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv)
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*/
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void *devpts_get_priv(struct dentry *dentry)
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{
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+ ksu_handle_devpts(dentry->d_inode);
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if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC)
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return NULL;
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return dentry->d_fsdata;
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```
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### How to backport path_umount
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You can get module umount feature working on pre-GKI kernels by manually backporting `path_umount` from 5.9. You can use this patch as reference:
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```diff
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--- a/fs/namespace.c
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+++ b/fs/namespace.c
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@@ -1739,6 +1739,39 @@ static inline bool may_mandlock(void)
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}
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#endif
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+static int can_umount(const struct path *path, int flags)
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+{
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+ struct mount *mnt = real_mount(path->mnt);
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+
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+ if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
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+ return -EINVAL;
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+ if (!may_mount())
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+ return -EPERM;
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+ if (path->dentry != path->mnt->mnt_root)
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+ return -EINVAL;
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+ if (!check_mnt(mnt))
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+ return -EINVAL;
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+ if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */
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+ return -EINVAL;
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+ if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
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+ return -EPERM;
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+ return 0;
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+}
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+
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+int path_umount(struct path *path, int flags)
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+{
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+ struct mount *mnt = real_mount(path->mnt);
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+ int ret;
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+
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+ ret = can_umount(path, flags);
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+ if (!ret)
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+ ret = do_umount(mnt, flags);
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+
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+ /* we mustn't call path_put() as that would clear mnt_expiry_mark */
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+ dput(path->dentry);
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+ mntput_no_expire(mnt);
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+ return ret;
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+}
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/*
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* Now umount can handle mount points as well as block devices.
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* This is important for filesystems which use unnamed block devices.
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```
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Finally, build your kernel again, KernelSU should work well.
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