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-rw-r--r--fs/efivarfs/file.c114
1 files changed, 114 insertions, 0 deletions
diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c
new file mode 100644
index 0000000000..59b52718a3
--- /dev/null
+++ b/fs/efivarfs/file.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Red Hat, Inc.
+ * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
+ */
+
+#include <linux/efi.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/mount.h>
+
+#include "internal.h"
+
+static ssize_t efivarfs_file_write(struct file *file,
+ const char __user *userbuf, size_t count, loff_t *ppos)
+{
+ struct efivar_entry *var = file->private_data;
+ void *data;
+ u32 attributes;
+ struct inode *inode = file->f_mapping->host;
+ unsigned long datasize = count - sizeof(attributes);
+ ssize_t bytes;
+ bool set = false;
+
+ if (count < sizeof(attributes))
+ return -EINVAL;
+
+ if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
+ return -EFAULT;
+
+ if (attributes & ~(EFI_VARIABLE_MASK))
+ return -EINVAL;
+
+ data = memdup_user(userbuf + sizeof(attributes), datasize);
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ bytes = efivar_entry_set_get_size(var, attributes, &datasize,
+ data, &set);
+ if (!set && bytes) {
+ if (bytes == -ENOENT)
+ bytes = -EIO;
+ goto out;
+ }
+
+ if (bytes == -ENOENT) {
+ drop_nlink(inode);
+ d_delete(file->f_path.dentry);
+ dput(file->f_path.dentry);
+ } else {
+ inode_lock(inode);
+ i_size_write(inode, datasize + sizeof(attributes));
+ inode->i_mtime = inode_set_ctime_current(inode);
+ inode_unlock(inode);
+ }
+
+ bytes = count;
+
+out:
+ kfree(data);
+
+ return bytes;
+}
+
+static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ struct efivar_entry *var = file->private_data;
+ unsigned long datasize = 0;
+ u32 attributes;
+ void *data;
+ ssize_t size = 0;
+ int err;
+
+ while (!__ratelimit(&file->f_cred->user->ratelimit))
+ msleep(50);
+
+ err = efivar_entry_size(var, &datasize);
+
+ /*
+ * efivarfs represents uncommitted variables with
+ * zero-length files. Reading them should return EOF.
+ */
+ if (err == -ENOENT)
+ return 0;
+ else if (err)
+ return err;
+
+ data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
+
+ if (!data)
+ return -ENOMEM;
+
+ size = efivar_entry_get(var, &attributes, &datasize,
+ data + sizeof(attributes));
+ if (size)
+ goto out_free;
+
+ memcpy(data, &attributes, sizeof(attributes));
+ size = simple_read_from_buffer(userbuf, count, ppos,
+ data, datasize + sizeof(attributes));
+out_free:
+ kfree(data);
+
+ return size;
+}
+
+const struct file_operations efivarfs_file_operations = {
+ .open = simple_open,
+ .read = efivarfs_file_read,
+ .write = efivarfs_file_write,
+ .llseek = no_llseek,
+};