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dabao1955 edited this page Dec 12, 2023 · 8 revisions

集成KernelSU

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KernelSU 可以被集成到非 GKI 内核中，现在它最低支持到内核 4.14 版本；理论上也可以支持更低的版本。

通过kprobes集成

KernelSU 使用 kprobe 机制来做内核的相关 hook，如果 kprobe 可以在你编译的内核中正常运行，那么推荐用这个方法来集成。

首先，把 KernelSU 添加到你的内核源码树，在内核的根目录执行以下命令：

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

然后，你需要检查你的内核是否开启了 kprobe 相关的配置，如果没有开启，需要编辑配置文件查找并添加以下内容

CONFIG_KPROBES=y
CONFIG_HAVE_KPROBES=y
CONFIG_KPROBE_EVENTS=y
CONFIG_MODULES=y
CONFIG_OVERLAY_FS=y #模块运行依赖于overlayfs，不开也行

如果你在集成 KernelSU 之后手机无法启动，那么很可能你的内核中 kprobe 工作不正常，你需要修复这个 bug 或者用第二种方法。

如何验证是否是 kprobe 的问题？

注释掉 KernelSU/kernel/ksu.c 中 ksu_enable_sucompat() 和 ksu_enable_ksud()，如果正常开机，那么就是 kprobe 的问题；或者你可以手动尝试使用 kprobe 功能，如果不正常，手机会直接重启。

手动添加kernelSU

主要是要改四个地方：

  • do_faccessat，通常位于 fs/open.c

参考

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)
 {
 	const struct cred *old_cred;
 	struct cred *override_cred;
 	struct path path;
 	struct inode *inode;
 	struct vfsmount *mnt;
 	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;
  • do_execveat_common，通常位于 fs/exec.c

参考

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 bool ksu_execveat_hook __read_mostly;
+extern int ksu_handle_execveat(int *fd, struct filename **filename_ptr, void *argv,
+			void *envp, int *flags);
+extern int ksu_handle_execveat_sucompat(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)
 {
+	if (unlikely(ksu_execveat_hook))
+		ksu_handle_execveat(&fd, &filename, &argv, &envp, &flags);
+	else
+		ksu_handle_execveat_sucompat(&fd, &filename, &argv, &envp, &flags);
 	return __do_execve_file(fd, filename, argv, envp, flags, NULL);
 }
  • vfs_read，通常位于 fs/read_write.c

参考

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 bool ksu_vfs_read_hook __read_mostly;
+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;
 
+	if (unlikely(ksu_vfs_read_hook))
+		ksu_handle_vfs_read(&file, &buf, &count, &pos);
+
 	if (!(file->f_mode & FMODE_READ))
 		return -EBADF;
 	if (!(file->f_mode & FMODE_CAN_READ))
  • vfs_statx，通常位于 fs/stat.c

参考

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;

如果你的内核没有 vfs_statx, 使用 vfs_fstatat 来代替它：

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;

对于早于 4.17 的内核，如果没有 do_faccessat，可以直接找到 faccessat 系统调用的定义然后修改：

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;

要使用 KernelSU 内置的安全模式，你还需要修改 drivers/input/input.c 中的 input_handle_event 方法：

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 bool ksu_input_hook __read_mostly;
+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);
+
+	if (unlikely(ksu_input_hook))
+		ksu_handle_input_handle_event(&type, &code, &value);
 
 	if (disposition != INPUT_IGNORE_EVENT && type != EV_SYN)
 		add_input_randomness(type, code, value);

然后重新编译即可。

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