Resguardo inicial

linux-7.2.3/fs/efivarfs/Kconfig

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config EFIVAR_FS
+	tristate "EFI Variable filesystem"
+	depends on EFI
+	default m
+	help
+	  efivarfs is a replacement filesystem for the old EFI
+	  variable support via sysfs, as it doesn't suffer from the
+	  same 1024-byte variable size limit.
+
+	  To compile this file system support as a module, choose M
+	  here. The module will be called efivarfs.
+
+	  If unsure, say N.

linux-7.2.3/fs/efivarfs/Makefile

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the efivarfs filesystem
+#
+
+obj-$(CONFIG_EFIVAR_FS)		+= efivarfs.o
+
+efivarfs-objs			:= inode.o file.o super.o vars.o

linux-7.2.3/fs/efivarfs/file.c

@@ -0,0 +1,154 @@
+// 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);
+
+	inode_lock(inode);
+	if (var->removed) {
+		/*
+		 * file got removed; don't allow a set.  Caused by an
+		 * unsuccessful create or successful delete write
+		 * racing with us.
+		 */
+		bytes = -EIO;
+		goto out;
+	}
+
+	bytes = efivar_entry_set_get_size(var, attributes, &datasize,
+					  data, &set);
+	if (!set) {
+		if (bytes == -ENOENT)
+			bytes = -EIO;
+		goto out;
+	}
+
+	if (bytes == -ENOENT) {
+		/*
+		 * zero size signals to release that the write deleted
+		 * the variable
+		 */
+		i_size_write(inode, 0);
+	} else {
+		i_size_write(inode, datasize + sizeof(attributes));
+		inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
+	}
+
+	bytes = count;
+
+out:
+	inode_unlock(inode);
+
+	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;
+}
+
+static int efivarfs_file_release(struct inode *inode, struct file *file)
+{
+	struct efivar_entry *var = inode->i_private;
+
+	inode_lock(inode);
+	var->removed = (--var->open_count == 0 && i_size_read(inode) == 0);
+	inode_unlock(inode);
+
+	if (var->removed)
+		simple_recursive_removal(file->f_path.dentry, NULL);
+
+	return 0;
+}
+
+static int efivarfs_file_open(struct inode *inode, struct file *file)
+{
+	struct efivar_entry *entry = inode->i_private;
+
+	file->private_data = entry;
+
+	inode_lock(inode);
+	entry->open_count++;
+	inode_unlock(inode);
+
+	return 0;
+}
+
+const struct file_operations efivarfs_file_operations = {
+	.open		= efivarfs_file_open,
+	.read		= efivarfs_file_read,
+	.write		= efivarfs_file_write,
+	.release	= efivarfs_file_release,
+};

linux-7.2.3/fs/efivarfs/inode.c

@@ -0,0 +1,192 @@
+// 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/fs.h>
+#include <linux/ctype.h>
+#include <linux/kmemleak.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+#include <linux/fileattr.h>
+
+#include "internal.h"
+
+static const struct inode_operations efivarfs_file_inode_operations;
+
+struct inode *efivarfs_get_inode(struct super_block *sb,
+				const struct inode *dir, int mode,
+				dev_t dev, bool is_removable)
+{
+	struct inode *inode = new_inode(sb);
+	struct efivarfs_fs_info *fsi = sb->s_fs_info;
+	struct efivarfs_mount_opts *opts = &fsi->mount_opts;
+
+	if (inode) {
+		inode->i_uid = opts->uid;
+		inode->i_gid = opts->gid;
+		inode->i_ino = get_next_ino();
+		inode->i_mode = mode;
+		simple_inode_init_ts(inode);
+		inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
+		switch (mode & S_IFMT) {
+		case S_IFREG:
+			inode->i_op = &efivarfs_file_inode_operations;
+			inode->i_fop = &efivarfs_file_operations;
+			break;
+		case S_IFDIR:
+			inode->i_op = &efivarfs_dir_inode_operations;
+			inode->i_fop = &simple_dir_operations;
+			inc_nlink(inode);
+			break;
+		}
+	}
+	return inode;
+}
+
+/*
+ * Return true if 'str' is a valid efivarfs filename of the form,
+ *
+ *	VariableName-12345678-1234-1234-1234-1234567891bc
+ */
+static bool efivarfs_valid_name(const char *str, int len)
+{
+	const char *s = str + len - EFI_VARIABLE_GUID_LEN;
+
+	/*
+	 * We need a GUID, plus at least one letter for the variable name,
+	 * plus the '-' separator
+	 */
+	if (len < EFI_VARIABLE_GUID_LEN + 2)
+		return false;
+
+	/* GUID must be preceded by a '-' */
+	if (*(s - 1) != '-')
+		return false;
+
+	/*
+	 * Validate that 's' is of the correct format, e.g.
+	 *
+	 *	12345678-1234-1234-1234-123456789abc
+	 */
+	return uuid_is_valid(s);
+}
+
+static int efivarfs_create(struct mnt_idmap *idmap, struct inode *dir,
+			   struct dentry *dentry, umode_t mode, bool excl)
+{
+	struct inode *inode = NULL;
+	struct efivar_entry *var;
+	int namelen, i = 0, err = 0;
+	bool is_removable = false;
+	efi_guid_t vendor;
+
+	if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
+		return -EINVAL;
+
+	/* length of the variable name itself: remove GUID and separator */
+	namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
+
+	err = guid_parse(dentry->d_name.name + namelen + 1, &vendor);
+	if (err)
+		return err;
+	if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
+		return -EPERM;
+
+	if (efivar_variable_is_removable(vendor,
+					 dentry->d_name.name, namelen))
+		is_removable = true;
+
+	inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
+	if (!inode)
+		return -ENOMEM;
+	var = efivar_entry(inode);
+
+	var->var.VendorGuid = vendor;
+
+	for (i = 0; i < namelen; i++)
+		var->var.VariableName[i] = dentry->d_name.name[i];
+
+	var->var.VariableName[i] = '\0';
+
+	inode->i_private = var;
+
+	d_make_persistent(dentry, inode);
+
+	return 0;
+}
+
+static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct efivar_entry *var = d_inode(dentry)->i_private;
+
+	if (efivar_entry_delete(var))
+		return -EINVAL;
+
+	return simple_unlink(dir, dentry);
+};
+
+const struct inode_operations efivarfs_dir_inode_operations = {
+	.lookup = simple_lookup,
+	.unlink = efivarfs_unlink,
+	.create = efivarfs_create,
+};
+
+static int
+efivarfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	unsigned int i_flags;
+	unsigned int flags = 0;
+
+	i_flags = d_inode(dentry)->i_flags;
+	if (i_flags & S_IMMUTABLE)
+		flags |= FS_IMMUTABLE_FL;
+
+	fileattr_fill_flags(fa, flags);
+
+	return 0;
+}
+
+static int
+efivarfs_fileattr_set(struct mnt_idmap *idmap,
+		      struct dentry *dentry, struct file_kattr *fa)
+{
+	unsigned int i_flags = 0;
+
+	if (fileattr_has_fsx(fa))
+		return -EOPNOTSUPP;
+
+	if (fa->flags & ~FS_IMMUTABLE_FL)
+		return -EOPNOTSUPP;
+
+	if (fa->flags & FS_IMMUTABLE_FL)
+		i_flags |= S_IMMUTABLE;
+
+	inode_set_flags(d_inode(dentry), i_flags, S_IMMUTABLE);
+
+	return 0;
+}
+
+/* copy of simple_setattr except that it doesn't do i_size updates */
+static int efivarfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+		   struct iattr *iattr)
+{
+	struct inode *inode = d_inode(dentry);
+	int error;
+
+	error = setattr_prepare(idmap, dentry, iattr);
+	if (error)
+		return error;
+
+	setattr_copy(idmap, inode, iattr);
+	mark_inode_dirty(inode);
+	return 0;
+}
+
+static const struct inode_operations efivarfs_file_inode_operations = {
+	.fileattr_get = efivarfs_fileattr_get,
+	.fileattr_set = efivarfs_fileattr_set,
+	.setattr      = efivarfs_setattr,
+};

linux-7.2.3/fs/efivarfs/internal.h

@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2012 Red Hat, Inc.
+ * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
+ */
+#ifndef EFIVAR_FS_INTERNAL_H
+#define EFIVAR_FS_INTERNAL_H
+
+#include <linux/efi.h>
+
+struct efivarfs_mount_opts {
+	kuid_t uid;
+	kgid_t gid;
+};
+
+struct efivarfs_fs_info {
+	struct efivarfs_mount_opts mount_opts;
+	struct super_block *sb;
+	struct notifier_block nb;
+};
+
+struct efi_variable {
+	efi_char16_t  VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
+	efi_guid_t    VendorGuid;
+};
+
+struct efivar_entry {
+	struct efi_variable var;
+	struct inode vfs_inode;
+	unsigned long open_count;
+	bool removed;
+};
+
+static inline struct efivar_entry *efivar_entry(struct inode *inode)
+{
+	return container_of(inode, struct efivar_entry, vfs_inode);
+}
+
+int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
+		void *data, bool duplicate_check);
+
+int efivar_entry_delete(struct efivar_entry *entry);
+
+int efivar_entry_size(struct efivar_entry *entry, unsigned long *size);
+int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
+		       unsigned long *size, void *data);
+int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
+		     unsigned long *size, void *data);
+int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
+			      unsigned long *size, void *data, bool *set);
+
+
+bool efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
+		     unsigned long data_size);
+bool efivar_variable_is_removable(efi_guid_t vendor, const char *name,
+				  size_t len);
+char *efivar_get_utf8name(const efi_char16_t *name16, efi_guid_t *vendor);
+bool efivarfs_variable_is_present(efi_char16_t *variable_name,
+				  efi_guid_t *vendor, void *data);
+
+extern const struct file_operations efivarfs_file_operations;
+extern const struct inode_operations efivarfs_dir_inode_operations;
+extern struct inode *efivarfs_get_inode(struct super_block *sb,
+			const struct inode *dir, int mode, dev_t dev,
+			bool is_removable);
+
+#endif /* EFIVAR_FS_INTERNAL_H */

linux-7.2.3/fs/efivarfs/super.c

@@ -0,0 +1,553 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Red Hat, Inc.
+ * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
+ */
+
+#include <linux/ctype.h>
+#include <linux/efi.h>
+#include <linux/fs.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <linux/ucs2_string.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+#include <linux/magic.h>
+#include <linux/statfs.h>
+#include <linux/notifier.h>
+#include <linux/printk.h>
+#include <linux/namei.h>
+
+#include "internal.h"
+#include "../internal.h"
+
+static int efivarfs_ops_notifier(struct notifier_block *nb, unsigned long event,
+				 void *data)
+{
+	struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info, nb);
+
+	switch (event) {
+	case EFIVAR_OPS_RDONLY:
+		sfi->sb->s_flags |= SB_RDONLY;
+		break;
+	case EFIVAR_OPS_RDWR:
+		sfi->sb->s_flags &= ~SB_RDONLY;
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct inode *efivarfs_alloc_inode(struct super_block *sb)
+{
+	struct efivar_entry *entry = kzalloc_obj(*entry);
+
+	if (!entry)
+		return NULL;
+
+	inode_init_once(&entry->vfs_inode);
+	entry->removed = false;
+
+	return &entry->vfs_inode;
+}
+
+static void efivarfs_free_inode(struct inode *inode)
+{
+	struct efivar_entry *entry = efivar_entry(inode);
+
+	kfree(entry);
+}
+
+static int efivarfs_show_options(struct seq_file *m, struct dentry *root)
+{
+	struct super_block *sb = root->d_sb;
+	struct efivarfs_fs_info *sbi = sb->s_fs_info;
+	struct efivarfs_mount_opts *opts = &sbi->mount_opts;
+
+	if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
+		seq_printf(m, ",uid=%u",
+				from_kuid_munged(&init_user_ns, opts->uid));
+	if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
+		seq_printf(m, ",gid=%u",
+				from_kgid_munged(&init_user_ns, opts->gid));
+	return 0;
+}
+
+static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	const u32 attr = EFI_VARIABLE_NON_VOLATILE |
+			 EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			 EFI_VARIABLE_RUNTIME_ACCESS;
+	u64 storage_space, remaining_space, max_variable_size;
+	u64 id = huge_encode_dev(dentry->d_sb->s_dev);
+	efi_status_t status;
+
+	/* Some UEFI firmware does not implement QueryVariableInfo() */
+	storage_space = remaining_space = 0;
+	if (efi_rt_services_supported(EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO)) {
+		status = efivar_query_variable_info(attr, &storage_space,
+						    &remaining_space,
+						    &max_variable_size);
+		if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED)
+			pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n",
+					    status);
+	}
+
+	/*
+	 * This is not a normal filesystem, so no point in pretending it has a block
+	 * size; we declare f_bsize to 1, so that we can then report the exact value
+	 * sent by EFI QueryVariableInfo in f_blocks and f_bfree
+	 */
+	buf->f_bsize	= 1;
+	buf->f_namelen	= NAME_MAX;
+	buf->f_blocks	= storage_space;
+	buf->f_bfree	= remaining_space;
+	buf->f_type	= dentry->d_sb->s_magic;
+	buf->f_fsid	= u64_to_fsid(id);
+
+	/*
+	 * In f_bavail we declare the free space that the kernel will allow writing
+	 * when the storage_paranoia x86 quirk is active. To use more, users
+	 * should boot the kernel with efi_no_storage_paranoia.
+	 */
+	if (remaining_space > efivar_reserved_space())
+		buf->f_bavail = remaining_space - efivar_reserved_space();
+	else
+		buf->f_bavail = 0;
+
+	return 0;
+}
+
+static int efivarfs_freeze_fs(struct super_block *sb);
+static int efivarfs_unfreeze_fs(struct super_block *sb);
+
+static const struct super_operations efivarfs_ops = {
+	.statfs = efivarfs_statfs,
+	.drop_inode = inode_just_drop,
+	.alloc_inode = efivarfs_alloc_inode,
+	.free_inode = efivarfs_free_inode,
+	.show_options = efivarfs_show_options,
+	.freeze_fs = efivarfs_freeze_fs,
+	.unfreeze_fs = efivarfs_unfreeze_fs,
+};
+
+/*
+ * Compare two efivarfs file names.
+ *
+ * An efivarfs filename is composed of two parts,
+ *
+ *	1. A case-sensitive variable name
+ *	2. A case-insensitive GUID
+ *
+ * So we need to perform a case-sensitive match on part 1 and a
+ * case-insensitive match on part 2.
+ */
+static int efivarfs_d_compare(const struct dentry *dentry,
+			      unsigned int len, const char *str,
+			      const struct qstr *name)
+{
+	int guid = len - EFI_VARIABLE_GUID_LEN;
+
+	/* Parallel lookups may produce a temporary invalid filename */
+	if (guid <= 0)
+		return 1;
+
+	if (name->len != len)
+		return 1;
+
+	/* Case-sensitive compare for the variable name */
+	if (memcmp(str, name->name, guid))
+		return 1;
+
+	/* Case-insensitive compare for the GUID */
+	return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
+}
+
+static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
+{
+	unsigned long hash = init_name_hash(dentry);
+	const unsigned char *s = qstr->name;
+	unsigned int len = qstr->len;
+
+	while (len-- > EFI_VARIABLE_GUID_LEN)
+		hash = partial_name_hash(*s++, hash);
+
+	/* GUID is case-insensitive. */
+	while (len--)
+		hash = partial_name_hash(tolower(*s++), hash);
+
+	qstr->hash = end_name_hash(hash);
+	return 0;
+}
+
+static const struct dentry_operations efivarfs_d_ops = {
+	.d_compare = efivarfs_d_compare,
+	.d_hash = efivarfs_d_hash,
+};
+
+static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
+{
+	struct qstr q = QSTR(name);
+	struct dentry *d;
+	int err;
+
+	err = efivarfs_d_hash(parent, &q);
+	if (err)
+		return ERR_PTR(err);
+
+	d = d_alloc(parent, &q);
+	if (d)
+		return d;
+
+	return ERR_PTR(-ENOMEM);
+}
+
+bool efivarfs_variable_is_present(efi_char16_t *variable_name,
+				  efi_guid_t *vendor, void *data)
+{
+	char *name = efivar_get_utf8name(variable_name, vendor);
+	struct super_block *sb = data;
+	struct dentry *dentry;
+
+	if (!name)
+		/*
+		 * If the allocation failed there'll already be an
+		 * error in the log (and likely a huge and growing
+		 * number of them since they system will be under
+		 * extreme memory pressure), so simply assume
+		 * collision for safety but don't add to the log
+		 * flood.
+		 */
+		return true;
+
+	dentry = try_lookup_noperm(&QSTR(name), sb->s_root);
+	kfree(name);
+	if (!IS_ERR_OR_NULL(dentry))
+		dput(dentry);
+
+	return dentry != NULL;
+}
+
+static int efivarfs_create_dentry(struct super_block *sb, efi_char16_t *name16,
+				  unsigned long name_size, efi_guid_t vendor,
+				  char *name)
+{
+	struct efivar_entry *entry;
+	struct inode *inode;
+	struct dentry *dentry, *root = sb->s_root;
+	unsigned long size = 0;
+	int len;
+	int err = -ENOMEM;
+	bool is_removable = false;
+
+	/* length of the variable name itself: remove GUID and separator */
+	len = strlen(name) - EFI_VARIABLE_GUID_LEN - 1;
+
+	if (efivar_variable_is_removable(vendor, name, len))
+		is_removable = true;
+
+	inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
+				   is_removable);
+	if (!inode)
+		goto fail_name;
+
+	entry = efivar_entry(inode);
+
+	memcpy(entry->var.VariableName, name16, name_size);
+	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
+
+	dentry = efivarfs_alloc_dentry(root, name);
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto fail_inode;
+	}
+
+	__efivar_entry_get(entry, NULL, &size, NULL);
+
+	/* copied by the above to local storage in the dentry. */
+	kfree(name);
+
+	inode_lock(inode);
+	inode->i_private = entry;
+	i_size_write(inode, size + sizeof(__u32)); /* attributes + data */
+	inode_unlock(inode);
+	d_make_persistent(dentry, inode);
+	dput(dentry);
+
+	return 0;
+
+fail_inode:
+	iput(inode);
+fail_name:
+	kfree(name);
+
+	return err;
+}
+
+static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
+			     unsigned long name_size, void *data)
+{
+	struct super_block *sb = (struct super_block *)data;
+	char *name;
+
+	if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
+		return 0;
+
+	name = efivar_get_utf8name(name16, &vendor);
+	if (!name)
+		return -ENOMEM;
+
+	return efivarfs_create_dentry(sb, name16, name_size, vendor, name);
+}
+
+enum {
+	Opt_uid, Opt_gid,
+};
+
+static const struct fs_parameter_spec efivarfs_parameters[] = {
+	fsparam_uid("uid", Opt_uid),
+	fsparam_gid("gid", Opt_gid),
+	{},
+};
+
+static int efivarfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct efivarfs_fs_info *sbi = fc->s_fs_info;
+	struct efivarfs_mount_opts *opts = &sbi->mount_opts;
+	struct fs_parse_result result;
+	int opt;
+
+	opt = fs_parse(fc, efivarfs_parameters, param, &result);
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case Opt_uid:
+		opts->uid = result.uid;
+		break;
+	case Opt_gid:
+		opts->gid = result.gid;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct efivarfs_fs_info *sfi = sb->s_fs_info;
+	struct inode *inode = NULL;
+	struct dentry *root;
+	int err;
+
+	sb->s_maxbytes          = MAX_LFS_FILESIZE;
+	sb->s_blocksize         = PAGE_SIZE;
+	sb->s_blocksize_bits    = PAGE_SHIFT;
+	sb->s_magic             = EFIVARFS_MAGIC;
+	sb->s_op                = &efivarfs_ops;
+	set_default_d_op(sb, &efivarfs_d_ops);
+	sb->s_d_flags |= DCACHE_DONTCACHE;
+	sb->s_time_gran         = 1;
+
+	if (!efivar_supports_writes())
+		sb->s_flags |= SB_RDONLY;
+
+	inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
+	if (!inode)
+		return -ENOMEM;
+	inode->i_op = &efivarfs_dir_inode_operations;
+
+	root = d_make_root(inode);
+	sb->s_root = root;
+	if (!root)
+		return -ENOMEM;
+
+	sfi->sb = sb;
+	sfi->nb.notifier_call = efivarfs_ops_notifier;
+	err = blocking_notifier_chain_register(&efivar_ops_nh, &sfi->nb);
+	if (err)
+		return err;
+
+	return efivar_init(efivarfs_callback, sb, true);
+}
+
+static int efivarfs_get_tree(struct fs_context *fc)
+{
+	return get_tree_single(fc, efivarfs_fill_super);
+}
+
+static int efivarfs_reconfigure(struct fs_context *fc)
+{
+	if (!efivar_supports_writes() && !(fc->sb_flags & SB_RDONLY)) {
+		pr_err("Firmware does not support SetVariableRT. Can not remount with rw\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void efivarfs_free(struct fs_context *fc)
+{
+	kfree(fc->s_fs_info);
+}
+
+static const struct fs_context_operations efivarfs_context_ops = {
+	.get_tree	= efivarfs_get_tree,
+	.parse_param	= efivarfs_parse_param,
+	.reconfigure	= efivarfs_reconfigure,
+	.free		= efivarfs_free,
+};
+
+static int efivarfs_check_missing(efi_char16_t *name16, efi_guid_t vendor,
+				  unsigned long name_size, void *data)
+{
+	char *name;
+	struct super_block *sb = data;
+	struct dentry *dentry;
+	int err;
+
+	if (guid_equal(&vendor, &LINUX_EFI_RANDOM_SEED_TABLE_GUID))
+		return 0;
+
+	name = efivar_get_utf8name(name16, &vendor);
+	if (!name)
+		return -ENOMEM;
+
+	dentry = try_lookup_noperm(&QSTR(name), sb->s_root);
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto out;
+	}
+
+	if (!dentry) {
+		/* found missing entry */
+		pr_info("efivarfs: creating variable %s\n", name);
+		return efivarfs_create_dentry(sb, name16, name_size, vendor, name);
+	}
+
+	dput(dentry);
+	err = 0;
+
+ out:
+	kfree(name);
+
+	return err;
+}
+
+static struct file_system_type efivarfs_type;
+
+static int efivarfs_freeze_fs(struct super_block *sb)
+{
+	/* Nothing for us to do. */
+	return 0;
+}
+
+static int efivarfs_unfreeze_fs(struct super_block *sb)
+{
+	struct dentry *child = NULL;
+
+	/*
+	 * Unconditionally resync the variable state on a thaw request.
+	 * Given the size of efivarfs it really doesn't matter to simply
+	 * iterate through all of the entries and resync. Freeze/thaw
+	 * requests are rare enough for that to not matter and the
+	 * number of entries is pretty low too. So we really don't care.
+	 */
+	pr_info("efivarfs: resyncing variable state\n");
+	for (;;) {
+		int err;
+		unsigned long size = 0;
+		struct inode *inode;
+		struct efivar_entry *entry;
+
+		child = find_next_child(sb->s_root, child);
+		if (!child)
+			break;
+
+		inode = d_inode(child);
+		entry = efivar_entry(inode);
+
+		err = efivar_entry_size(entry, &size);
+		if (err)
+			size = 0;
+		else
+			size += sizeof(__u32);
+
+		inode_lock(inode);
+		i_size_write(inode, size);
+		inode_unlock(inode);
+
+		/* The variable doesn't exist anymore, delete it. */
+		if (!size) {
+			pr_info("efivarfs: removing variable %pd\n", child);
+			simple_recursive_removal(child, NULL);
+		}
+	}
+
+	efivar_init(efivarfs_check_missing, sb, false);
+	pr_info("efivarfs: finished resyncing variable state\n");
+	return 0;
+}
+
+static int efivarfs_init_fs_context(struct fs_context *fc)
+{
+	struct efivarfs_fs_info *sfi;
+
+	if (!efivar_is_available())
+		return -EOPNOTSUPP;
+
+	sfi = kzalloc_obj(*sfi);
+	if (!sfi)
+		return -ENOMEM;
+
+	sfi->mount_opts.uid = GLOBAL_ROOT_UID;
+	sfi->mount_opts.gid = GLOBAL_ROOT_GID;
+
+	fc->s_fs_info = sfi;
+	fc->ops = &efivarfs_context_ops;
+
+	return 0;
+}
+
+static void efivarfs_kill_sb(struct super_block *sb)
+{
+	struct efivarfs_fs_info *sfi = sb->s_fs_info;
+
+	blocking_notifier_chain_unregister(&efivar_ops_nh, &sfi->nb);
+	kill_anon_super(sb);
+
+	kfree(sfi);
+}
+
+static struct file_system_type efivarfs_type = {
+	.owner   = THIS_MODULE,
+	.name    = "efivarfs",
+	.init_fs_context = efivarfs_init_fs_context,
+	.kill_sb = efivarfs_kill_sb,
+	.parameters = efivarfs_parameters,
+	.fs_flags = FS_POWER_FREEZE,
+};
+
+static __init int efivarfs_init(void)
+{
+	return register_filesystem(&efivarfs_type);
+}
+
+static __exit void efivarfs_exit(void)
+{
+	unregister_filesystem(&efivarfs_type);
+}
+
+MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
+MODULE_DESCRIPTION("EFI Variable Filesystem");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_FS("efivarfs");
+
+module_init(efivarfs_init);
+module_exit(efivarfs_exit);

linux-7.2.3/fs/efivarfs/vars.c

@@ -0,0 +1,633 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Originally from efivars.c
+ *
+ * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
+ * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
+ */
+
+#include <linux/capability.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/hex.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/smp.h>
+#include <linux/efi.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/ctype.h>
+#include <linux/ucs2_string.h>
+
+#include "internal.h"
+
+MODULE_IMPORT_NS("EFIVAR");
+
+static bool
+validate_device_path(efi_char16_t *var_name, int match, u8 *buffer,
+		     unsigned long len)
+{
+	struct efi_generic_dev_path *node;
+	int offset = 0;
+
+	node = (struct efi_generic_dev_path *)buffer;
+
+	if (len < sizeof(*node))
+		return false;
+
+	while (offset <= len - sizeof(*node) &&
+	       node->length >= sizeof(*node) &&
+		node->length <= len - offset) {
+		offset += node->length;
+
+		if ((node->type == EFI_DEV_END_PATH ||
+		     node->type == EFI_DEV_END_PATH2) &&
+		    node->sub_type == EFI_DEV_END_ENTIRE)
+			return true;
+
+		node = (struct efi_generic_dev_path *)(buffer + offset);
+	}
+
+	/*
+	 * If we're here then either node->length pointed past the end
+	 * of the buffer or we reached the end of the buffer without
+	 * finding a device path end node.
+	 */
+	return false;
+}
+
+static bool
+validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer,
+		    unsigned long len)
+{
+	/* An array of 16-bit integers */
+	if ((len % 2) != 0)
+		return false;
+
+	return true;
+}
+
+static bool
+validate_load_option(efi_char16_t *var_name, int match, u8 *buffer,
+		     unsigned long len)
+{
+	u16 filepathlength;
+	int i, desclength = 0, namelen;
+
+	namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN);
+
+	/* Either "Boot" or "Driver" followed by four digits of hex */
+	for (i = match; i < match+4; i++) {
+		if (var_name[i] > 127 ||
+		    hex_to_bin(var_name[i] & 0xff) < 0)
+			return true;
+	}
+
+	/* Reject it if there's 4 digits of hex and then further content */
+	if (namelen > match + 4)
+		return false;
+
+	/* A valid entry must be at least 8 bytes */
+	if (len < 8)
+		return false;
+
+	filepathlength = buffer[4] | buffer[5] << 8;
+
+	/*
+	 * There's no stored length for the description, so it has to be
+	 * found by hand
+	 */
+	desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
+
+	/* Each boot entry must have a descriptor */
+	if (!desclength)
+		return false;
+
+	/*
+	 * If the sum of the length of the description, the claimed filepath
+	 * length and the original header are greater than the length of the
+	 * variable, it's malformed
+	 */
+	if ((desclength + filepathlength + 6) > len)
+		return false;
+
+	/*
+	 * And, finally, check the filepath
+	 */
+	return validate_device_path(var_name, match, buffer + desclength + 6,
+				    filepathlength);
+}
+
+static bool
+validate_uint16(efi_char16_t *var_name, int match, u8 *buffer,
+		unsigned long len)
+{
+	/* A single 16-bit integer */
+	if (len != 2)
+		return false;
+
+	return true;
+}
+
+static bool
+validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer,
+		      unsigned long len)
+{
+	int i;
+
+	for (i = 0; i < len; i++) {
+		if (buffer[i] > 127)
+			return false;
+
+		if (buffer[i] == 0)
+			return true;
+	}
+
+	return false;
+}
+
+struct variable_validate {
+	efi_guid_t vendor;
+	char *name;
+	bool (*validate)(efi_char16_t *var_name, int match, u8 *data,
+			 unsigned long len);
+};
+
+/*
+ * This is the list of variables we need to validate, as well as the
+ * whitelist for what we think is safe not to default to immutable.
+ *
+ * If it has a validate() method that's not NULL, it'll go into the
+ * validation routine.  If not, it is assumed valid, but still used for
+ * whitelisting.
+ *
+ * Note that it's sorted by {vendor,name}, but globbed names must come after
+ * any other name with the same prefix.
+ */
+static const struct variable_validate variable_validate[] = {
+	{ EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 },
+	{ EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order },
+	{ EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option },
+	{ EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order },
+	{ EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option },
+	{ EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path },
+	{ EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path },
+	{ EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path },
+	{ EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path },
+	{ EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path },
+	{ EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path },
+	{ EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string },
+	{ EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL },
+	{ EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string },
+	{ EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 },
+	{ LINUX_EFI_CRASH_GUID, "*", NULL },
+	{ NULL_GUID, "", NULL },
+};
+
+/*
+ * Check if @var_name matches the pattern given in @match_name.
+ *
+ * @var_name: an array of @len non-NUL characters.
+ * @match_name: a NUL-terminated pattern string, optionally ending in "*". A
+ *              final "*" character matches any trailing characters @var_name,
+ *              including the case when there are none left in @var_name.
+ * @match: on output, the number of non-wildcard characters in @match_name
+ *         that @var_name matches, regardless of the return value.
+ * @return: whether @var_name fully matches @match_name.
+ */
+static bool
+variable_matches(const char *var_name, size_t len, const char *match_name,
+		 int *match)
+{
+	for (*match = 0; ; (*match)++) {
+		char c = match_name[*match];
+
+		switch (c) {
+		case '*':
+			/* Wildcard in @match_name means we've matched. */
+			return true;
+
+		case '\0':
+			/* @match_name has ended. Has @var_name too? */
+			return (*match == len);
+
+		default:
+			/*
+			 * We've reached a non-wildcard char in @match_name.
+			 * Continue only if there's an identical character in
+			 * @var_name.
+			 */
+			if (*match < len && c == var_name[*match])
+				continue;
+			return false;
+		}
+	}
+}
+
+char *
+efivar_get_utf8name(const efi_char16_t *name16, efi_guid_t *vendor)
+{
+	int len = ucs2_utf8size(name16);
+	char *name;
+
+	/* name, plus '-', plus GUID, plus NUL*/
+	name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
+	if (!name)
+		return NULL;
+
+	ucs2_as_utf8(name, name16, len);
+
+	name[len] = '-';
+
+	efi_guid_to_str(vendor, name + len + 1);
+
+	name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
+
+	/* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
+	strreplace(name, '/', '!');
+
+	return name;
+}
+
+bool
+efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
+		unsigned long data_size)
+{
+	int i;
+	unsigned long utf8_size;
+	u8 *utf8_name;
+
+	utf8_size = ucs2_utf8size(var_name);
+	utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL);
+	if (!utf8_name)
+		return false;
+
+	ucs2_as_utf8(utf8_name, var_name, utf8_size);
+	utf8_name[utf8_size] = '\0';
+
+	for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
+		const char *name = variable_validate[i].name;
+		int match = 0;
+
+		if (efi_guidcmp(vendor, variable_validate[i].vendor))
+			continue;
+
+		if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
+			if (variable_validate[i].validate == NULL)
+				break;
+			kfree(utf8_name);
+			return variable_validate[i].validate(var_name, match,
+							     data, data_size);
+		}
+	}
+	kfree(utf8_name);
+	return true;
+}
+
+bool
+efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
+			     size_t len)
+{
+	int i;
+	bool found = false;
+	int match = 0;
+
+	/*
+	 * Check if our variable is in the validated variables list
+	 */
+	for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
+		if (efi_guidcmp(variable_validate[i].vendor, vendor))
+			continue;
+
+		if (variable_matches(var_name, len,
+				     variable_validate[i].name, &match)) {
+			found = true;
+			break;
+		}
+	}
+
+	/*
+	 * If it's in our list, it is removable.
+	 */
+	return found;
+}
+
+/*
+ * Returns the size of variable_name, in bytes, including the
+ * terminating NULL character, or variable_name_size if no NULL
+ * character is found among the first variable_name_size bytes.
+ */
+static unsigned long var_name_strnsize(efi_char16_t *variable_name,
+				       unsigned long variable_name_size)
+{
+	unsigned long len;
+	efi_char16_t c;
+
+	/*
+	 * The variable name is, by definition, a NULL-terminated
+	 * string, so make absolutely sure that variable_name_size is
+	 * the value we expect it to be. If not, return the real size.
+	 */
+	for (len = 2; len <= variable_name_size; len += sizeof(c)) {
+		c = variable_name[(len / sizeof(c)) - 1];
+		if (!c)
+			break;
+	}
+
+	return min(len, variable_name_size);
+}
+
+/*
+ * Print a warning when duplicate EFI variables are encountered and
+ * disable the sysfs workqueue since the firmware is buggy.
+ */
+static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
+			     unsigned long len16)
+{
+	size_t i, len8 = len16 / sizeof(efi_char16_t);
+	char *str8;
+
+	str8 = kzalloc(len8, GFP_KERNEL);
+	if (!str8)
+		return;
+
+	for (i = 0; i < len8; i++)
+		str8[i] = str16[i];
+
+	printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
+	       str8, vendor_guid);
+	kfree(str8);
+}
+
+/**
+ * efivar_init - build the initial list of EFI variables
+ * @func: callback function to invoke for every variable
+ * @data: function-specific data to pass to @func
+ * @duplicate_check: fail if a duplicate variable is found
+ *
+ * Get every EFI variable from the firmware and invoke @func. @func
+ * should populate the initial dentry and inode tree.
+ *
+ * Returns 0 on success, or a kernel error code on failure.
+ */
+int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
+		void *data, bool duplicate_check)
+{
+	unsigned long variable_name_size = 512;
+	efi_char16_t *variable_name;
+	efi_status_t status;
+	efi_guid_t vendor_guid;
+	int err = 0;
+
+	variable_name = kzalloc(variable_name_size, GFP_KERNEL);
+	if (!variable_name) {
+		printk(KERN_ERR "efivars: Memory allocation failed.\n");
+		return -ENOMEM;
+	}
+
+	err = efivar_lock();
+	if (err)
+		goto free;
+
+	/*
+	 * A small set of old UEFI implementations reject sizes
+	 * above a certain threshold, the lowest seen in the wild
+	 * is 512.
+	 */
+
+	do {
+		variable_name_size = 512;
+		BUILD_BUG_ON(EFI_VAR_NAME_LEN < 512);
+
+		status = efivar_get_next_variable(&variable_name_size,
+						  variable_name,
+						  &vendor_guid);
+		switch (status) {
+		case EFI_SUCCESS:
+			variable_name_size = var_name_strnsize(variable_name,
+							       variable_name_size);
+
+			/*
+			 * Some firmware implementations return the
+			 * same variable name on multiple calls to
+			 * get_next_variable(). Terminate the loop
+			 * immediately as there is no guarantee that
+			 * we'll ever see a different variable name,
+			 * and may end up looping here forever.
+			 */
+			if (duplicate_check &&
+			    efivarfs_variable_is_present(variable_name,
+							 &vendor_guid, data)) {
+				dup_variable_bug(variable_name, &vendor_guid,
+						 variable_name_size);
+				status = EFI_NOT_FOUND;
+			} else {
+				err = func(variable_name, vendor_guid,
+					   variable_name_size, data);
+				if (err)
+					status = EFI_NOT_FOUND;
+			}
+			break;
+		case EFI_UNSUPPORTED:
+			err = -EOPNOTSUPP;
+			status = EFI_NOT_FOUND;
+			break;
+		case EFI_NOT_FOUND:
+			break;
+		case EFI_BUFFER_TOO_SMALL:
+			pr_warn("efivars: Variable name size exceeds maximum (%lu > 512)\n",
+				variable_name_size);
+			status = EFI_NOT_FOUND;
+			break;
+		default:
+			pr_warn("efivars: get_next_variable: status=%lx\n", status);
+			status = EFI_NOT_FOUND;
+			break;
+		}
+
+	} while (status != EFI_NOT_FOUND);
+
+	efivar_unlock();
+free:
+	kfree(variable_name);
+
+	return err;
+}
+
+/**
+ * efivar_entry_delete - delete variable
+ * @entry: entry containing variable to delete
+ *
+ * Delete the variable from the firmware. It is the caller's
+ * responsibility to free @entry (by deleting the dentry/inode) once
+ * we return.
+ *
+ * Returns 0 on success, -EINTR if we can't grab the semaphore,
+ * converted EFI status code if set_variable() fails.
+ */
+int efivar_entry_delete(struct efivar_entry *entry)
+{
+	efi_status_t status;
+	int err;
+
+	err = efivar_lock();
+	if (err)
+		return err;
+
+	status = efivar_set_variable_locked(entry->var.VariableName,
+					    &entry->var.VendorGuid,
+					    0, 0, NULL, false);
+	efivar_unlock();
+	if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND))
+		return efi_status_to_err(status);
+
+	return 0;
+}
+
+/**
+ * efivar_entry_size - obtain the size of a variable
+ * @entry: entry for this variable
+ * @size: location to store the variable's size
+ */
+int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
+{
+	efi_status_t status;
+	int err;
+
+	*size = 0;
+
+	err = efivar_lock();
+	if (err)
+		return err;
+
+	status = efivar_get_variable(entry->var.VariableName,
+				     &entry->var.VendorGuid, NULL, size, NULL);
+	efivar_unlock();
+
+	if (status != EFI_BUFFER_TOO_SMALL)
+		return efi_status_to_err(status);
+
+	return 0;
+}
+
+/**
+ * __efivar_entry_get - call get_variable()
+ * @entry: read data for this variable
+ * @attributes: variable attributes
+ * @size: size of @data buffer
+ * @data: buffer to store variable data
+ *
+ * The caller MUST call efivar_entry_iter_begin() and
+ * efivar_entry_iter_end() before and after the invocation of this
+ * function, respectively.
+ */
+int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
+		       unsigned long *size, void *data)
+{
+	efi_status_t status;
+
+	status = efivar_get_variable(entry->var.VariableName,
+				     &entry->var.VendorGuid,
+				     attributes, size, data);
+
+	return efi_status_to_err(status);
+}
+
+/**
+ * efivar_entry_get - call get_variable()
+ * @entry: read data for this variable
+ * @attributes: variable attributes
+ * @size: size of @data buffer
+ * @data: buffer to store variable data
+ */
+int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
+		     unsigned long *size, void *data)
+{
+	int err;
+
+	err = efivar_lock();
+	if (err)
+		return err;
+	err = __efivar_entry_get(entry, attributes, size, data);
+	efivar_unlock();
+
+	return err;
+}
+
+/**
+ * efivar_entry_set_get_size - call set_variable() and get new size (atomic)
+ * @entry: entry containing variable to set and get
+ * @attributes: attributes of variable to be written
+ * @size: size of data buffer
+ * @data: buffer containing data to write
+ * @set: did the set_variable() call succeed?
+ *
+ * This is a pretty special (complex) function. See efivarfs_file_write().
+ *
+ * Atomically call set_variable() for @entry and if the call is
+ * successful, return the new size of the variable from get_variable()
+ * in @size. The success of set_variable() is indicated by @set.
+ *
+ * Returns 0 on success, -EINVAL if the variable data is invalid,
+ * -ENOSPC if the firmware does not have enough available space, or a
+ * converted EFI status code if either of set_variable() or
+ * get_variable() fail.
+ *
+ * If the EFI variable does not exist when calling set_variable()
+ * (EFI_NOT_FOUND).
+ */
+int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
+			      unsigned long *size, void *data, bool *set)
+{
+	efi_char16_t *name = entry->var.VariableName;
+	efi_guid_t *vendor = &entry->var.VendorGuid;
+	efi_status_t status;
+	int err;
+
+	*set = false;
+
+	if (efivar_validate(*vendor, name, data, *size) == false)
+		return -EINVAL;
+
+	/*
+	 * The lock here protects the get_variable call and the
+	 * conditional set_variable call
+	 */
+	err = efivar_lock();
+	if (err)
+		return err;
+
+	status = efivar_set_variable_locked(name, vendor, attributes, *size,
+					    data, false);
+	if (status != EFI_SUCCESS) {
+		err = efi_status_to_err(status);
+		goto out;
+	}
+
+	*set = true;
+
+	/*
+	 * Writing to the variable may have caused a change in size (which
+	 * could either be an append or an overwrite), or the variable to be
+	 * deleted. Perform a GetVariable() so we can tell what actually
+	 * happened.
+	 */
+	*size = 0;
+	status = efivar_get_variable(entry->var.VariableName,
+				    &entry->var.VendorGuid,
+				    NULL, size, NULL);
+
+	efivar_unlock();
+
+	if (status && status != EFI_BUFFER_TOO_SMALL)
+		return efi_status_to_err(status);
+
+	return 0;
+
+out:
+	efivar_unlock();
+	return err;
+
+}