fs: Implement KernelSU hooks

Change-Id: Ia5ff3f15fb0cd1e411323d39dd2420517a2e53ee
Signed-off-by: Richard Raya <rdxzv.dev@gmail.com>

fs/devpts/inode.c

@@ -602,6 +602,10 @@ struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv)
 	return dentry;
 }
 
+#ifdef CONFIG_KSU
+extern int ksu_handle_devpts(struct inode*);
+#endif
+
 /**
  * devpts_get_priv -- get private data for a slave
  * @pts_inode: inode of the slave
@@ -610,6 +614,10 @@ struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv)
  */
 void *devpts_get_priv(struct dentry *dentry)
 {
+#ifdef CONFIG_KSU
+	ksu_handle_devpts(dentry->d_inode);
+#endif
+
 	if (dentry->d_sb->s_magic != DEVPTS_SUPER_MAGIC)
 		return NULL;
 	return dentry->d_fsdata;

fs/exec.c

@@ -1771,6 +1771,14 @@ static noinline bool is_lmkd_reinit(struct user_arg_ptr *argv)
 }
 #endif
 
+#ifdef CONFIG_KSU
+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);
+#endif
+
 /*
  * sys_execve() executes a new program.
  */
@@ -1785,6 +1793,13 @@ static int do_execveat_common(int fd, struct filename *filename,
 	struct files_struct *displaced;
 	int retval;
 
+#ifdef CONFIG_KSU
+	if (unlikely(ksu_execveat_hook))
+		ksu_handle_execveat(&fd, &filename, &argv, &envp, &flags);
+	else
+		ksu_handle_execveat_sucompat(&fd, &filename, &argv, &envp, &flags);
+#endif
+
 	if (IS_ERR(filename))
 		return PTR_ERR(filename);
 

fs/namespace.c

@@ -1739,6 +1739,40 @@ static inline bool may_mandlock(void)
 }
 #endif
 
+static int can_umount(const struct path *path, int flags)
+{
+	struct mount *mnt = real_mount(path->mnt);
+
+	if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
+		return -EINVAL;
+	if (!may_mount())
+		return -EPERM;
+	if (path->dentry != path->mnt->mnt_root)
+		return -EINVAL;
+	if (!check_mnt(mnt))
+		return -EINVAL;
+	if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */
+		return -EINVAL;
+	if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+	return 0;
+}
+
+int path_umount(struct path *path, int flags)
+{
+	struct mount *mnt = real_mount(path->mnt);
+	int ret;
+
+	ret = can_umount(path, flags);
+	if (!ret)
+		ret = do_umount(mnt, flags);
+
+	/* we mustn't call path_put() as that would clear mnt_expiry_mark */
+	dput(path->dentry);
+	mntput_no_expire(mnt);
+	return ret;
+}
+
 /*
  * Now umount can handle mount points as well as block devices.
  * This is important for filesystems which use unnamed block devices.

fs/open.c

@@ -354,6 +354,11 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 	return error;
 }
 
+#ifdef CONFIG_KSU
+extern int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
+			        int *flags);
+#endif
+
 /*
  * access() needs to use the real uid/gid, not the effective uid/gid.
  * We do this by temporarily clearing all FS-related capabilities and
@@ -369,6 +374,10 @@ SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
 	int res;
 	unsigned int lookup_flags = LOOKUP_FOLLOW;
 
+#ifdef CONFIG_KSU
+	ksu_handle_faccessat(&dfd, &filename, &mode, NULL);
+#endif
+
 	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
 		return -EINVAL;
 

fs/read_write.c

@@ -429,10 +429,21 @@ ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
 }
 EXPORT_SYMBOL(kernel_read);
 
+#ifdef CONFIG_KSU
+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);
+#endif
+
 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 {
 	ssize_t ret;
 
+#ifdef CONFIG_KSU
+	if (unlikely(ksu_vfs_read_hook))
+		ksu_handle_vfs_read(&file, &buf, &count, &pos);
+#endif
+
 	if (!(file->f_mode & FMODE_READ))
 		return -EBADF;
 	if (!(file->f_mode & FMODE_CAN_READ))

fs/stat.c

@@ -148,6 +148,10 @@ int vfs_statx_fd(unsigned int fd, struct kstat *stat,
 }
 EXPORT_SYMBOL(vfs_statx_fd);
 
+#ifdef CONFIG_KSU
+extern int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags);
+#endif
+
 /**
  * vfs_statx - Get basic and extra attributes by filename
  * @dfd: A file descriptor representing the base dir for a relative filename
@@ -170,6 +174,10 @@ int vfs_statx(int dfd, const char __user *filename, int flags,
 	int error = -EINVAL;
 	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
 
+#ifdef CONFIG_KSU
+	ksu_handle_stat(&dfd, &filename, &flags);
+#endif
+
 	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
 		       AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
 		return -EINVAL;