[PATCH] firmware_loader: load files from the mount namespace of init

[Topi Miettinen]

Instead of using the mount namespace of the current process to load
firmware files, use the mount namespace of init process.

Signed-off-by: Topi Miettinen <toiwoton@xxxxxxxxx>
---
 drivers/base/firmware_loader/main.c |  6 ++++--
 fs/exec.c                           | 25 +++++++++++++++++++++++++
 include/linux/fs.h                  |  2 ++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index 249add8c5e05..01f5315fae53 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -493,8 +493,10 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
 		}
 
 		fw_priv->size = 0;
-		rc = kernel_read_file_from_path(path, &buffer, &size,
-						msize, id);
+
+		/* load firmware files from the mount namespace of init */
+		rc = kernel_read_file_from_path_initns(path, &buffer,
+						       &size, msize, id);
 		if (rc) {
 			if (rc != -ENOENT)
 				dev_warn(device, "loading %s failed with error %d\n",
diff --git a/fs/exec.c b/fs/exec.c
index 74d88dab98dd..fda1364dc142 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -981,6 +981,31 @@ int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
 }
 EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
 
+int kernel_read_file_from_path_initns(const char *path, void **buf,
+				      loff_t *size, loff_t max_size,
+				      enum kernel_read_file_id id)
+{
+	struct file *file;
+	struct path root;
+	int ret;
+
+	if (!path || !*path)
+		return -EINVAL;
+
+	task_lock(&init_task);
+	get_fs_root(init_task.fs, &root);
+	task_unlock(&init_task);
+
+	file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
+	path_put(&root);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+
+	ret = kernel_read_file(file, buf, size, max_size, id);
+	fput(file);
+	return ret;
+}
+
 int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
 			     enum kernel_read_file_id id)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 98e0349adb52..616a64871b2e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2994,6 +2994,8 @@ extern int kernel_read_file(struct file *, void **, loff_t *, loff_t,
 			    enum kernel_read_file_id);
 extern int kernel_read_file_from_path(const char *, void **, loff_t *, loff_t,
 				      enum kernel_read_file_id);
+extern int kernel_read_file_from_path_initns(const char *, void **, loff_t *, loff_t,
+					     enum kernel_read_file_id);
 extern int kernel_read_file_from_fd(int, void **, loff_t *, loff_t,
 				    enum kernel_read_file_id);
 extern ssize_t kernel_read(struct file *, void *, size_t, loff_t *);
-- 
2.24.1


--------------299D982EB9ACEFC63BDD3988--