Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c
new file mode 100644
index 0000000..bb7bb3b
--- /dev/null
+++ b/kernel/usermode_driver.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * umd - User mode driver support
+ */
+#include <linux/shmem_fs.h>
+#include <linux/pipe_fs_i.h>
+#include <linux/mount.h>
+#include <linux/fs_struct.h>
+#include <linux/task_work.h>
+#include <linux/usermode_driver.h>
+
+static struct vfsmount *blob_to_mnt(const void *data, size_t len, const char *name)
+{
+ struct file_system_type *type;
+ struct vfsmount *mnt;
+ struct file *file;
+ ssize_t written;
+ loff_t pos = 0;
+
+ type = get_fs_type("tmpfs");
+ if (!type)
+ return ERR_PTR(-ENODEV);
+
+ mnt = kern_mount(type);
+ put_filesystem(type);
+ if (IS_ERR(mnt))
+ return mnt;
+
+ file = file_open_root(mnt->mnt_root, mnt, name, O_CREAT | O_WRONLY, 0700);
+ if (IS_ERR(file)) {
+ mntput(mnt);
+ return ERR_CAST(file);
+ }
+
+ written = kernel_write(file, data, len, &pos);
+ if (written != len) {
+ int err = written;
+ if (err >= 0)
+ err = -ENOMEM;
+ filp_close(file, NULL);
+ mntput(mnt);
+ return ERR_PTR(err);
+ }
+
+ fput(file);
+
+ /* Flush delayed fput so exec can open the file read-only */
+ flush_delayed_fput();
+ task_work_run();
+ return mnt;
+}
+
+/**
+ * umd_load_blob - Remember a blob of bytes for fork_usermode_driver
+ * @info: information about usermode driver
+ * @data: a blob of bytes that can be executed as a file
+ * @len: The lentgh of the blob
+ *
+ */
+int umd_load_blob(struct umd_info *info, const void *data, size_t len)
+{
+ struct vfsmount *mnt;
+
+ if (WARN_ON_ONCE(info->wd.dentry || info->wd.mnt))
+ return -EBUSY;
+
+ mnt = blob_to_mnt(data, len, info->driver_name);
+ if (IS_ERR(mnt))
+ return PTR_ERR(mnt);
+
+ info->wd.mnt = mnt;
+ info->wd.dentry = mnt->mnt_root;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(umd_load_blob);
+
+/**
+ * umd_unload_blob - Disassociate @info from a previously loaded blob
+ * @info: information about usermode driver
+ *
+ */
+int umd_unload_blob(struct umd_info *info)
+{
+ if (WARN_ON_ONCE(!info->wd.mnt ||
+ !info->wd.dentry ||
+ info->wd.mnt->mnt_root != info->wd.dentry))
+ return -EINVAL;
+
+ kern_unmount(info->wd.mnt);
+ info->wd.mnt = NULL;
+ info->wd.dentry = NULL;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(umd_unload_blob);
+
+static int umd_setup(struct subprocess_info *info, struct cred *new)
+{
+ struct umd_info *umd_info = info->data;
+ struct file *from_umh[2];
+ struct file *to_umh[2];
+ int err;
+
+ /* create pipe to send data to umh */
+ err = create_pipe_files(to_umh, 0);
+ if (err)
+ return err;
+ err = replace_fd(0, to_umh[0], 0);
+ fput(to_umh[0]);
+ if (err < 0) {
+ fput(to_umh[1]);
+ return err;
+ }
+
+ /* create pipe to receive data from umh */
+ err = create_pipe_files(from_umh, 0);
+ if (err) {
+ fput(to_umh[1]);
+ replace_fd(0, NULL, 0);
+ return err;
+ }
+ err = replace_fd(1, from_umh[1], 0);
+ fput(from_umh[1]);
+ if (err < 0) {
+ fput(to_umh[1]);
+ replace_fd(0, NULL, 0);
+ fput(from_umh[0]);
+ return err;
+ }
+
+ set_fs_pwd(current->fs, &umd_info->wd);
+ umd_info->pipe_to_umh = to_umh[1];
+ umd_info->pipe_from_umh = from_umh[0];
+ umd_info->tgid = get_pid(task_tgid(current));
+ return 0;
+}
+
+static void umd_cleanup(struct subprocess_info *info)
+{
+ struct umd_info *umd_info = info->data;
+
+ /* cleanup if umh_setup() was successful but exec failed */
+ if (info->retval)
+ umd_cleanup_helper(umd_info);
+}
+
+/**
+ * umd_cleanup_helper - release the resources which were allocated in umd_setup
+ * @info: information about usermode driver
+ */
+void umd_cleanup_helper(struct umd_info *info)
+{
+ fput(info->pipe_to_umh);
+ fput(info->pipe_from_umh);
+ put_pid(info->tgid);
+ info->tgid = NULL;
+}
+EXPORT_SYMBOL_GPL(umd_cleanup_helper);
+
+/**
+ * fork_usermode_driver - fork a usermode driver
+ * @info: information about usermode driver (shouldn't be NULL)
+ *
+ * Returns either negative error or zero which indicates success in
+ * executing a usermode driver. In such case 'struct umd_info *info'
+ * is populated with two pipes and a tgid of the process. The caller is
+ * responsible for health check of the user process, killing it via
+ * tgid, and closing the pipes when user process is no longer needed.
+ */
+int fork_usermode_driver(struct umd_info *info)
+{
+ struct subprocess_info *sub_info;
+ const char *argv[] = { info->driver_name, NULL };
+ int err;
+
+ if (WARN_ON_ONCE(info->tgid))
+ return -EBUSY;
+
+ err = -ENOMEM;
+ sub_info = call_usermodehelper_setup(info->driver_name,
+ (char **)argv, NULL, GFP_KERNEL,
+ umd_setup, umd_cleanup, info);
+ if (!sub_info)
+ goto out;
+
+ err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
+out:
+ return err;
+}
+EXPORT_SYMBOL_GPL(fork_usermode_driver);
+
+