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From bc390c0e405a4fe896dfc54c8e6e737e41661e28 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg@redhat.com>
Date: Fri, 5 Oct 2012 13:54:56 +0800
Subject: [PATCH 01/17] efi: Add support for a UEFI variable filesystem

The existing EFI variables code only supports variables of up to 1024
bytes. This limitation existed in version 0.99 of the EFI specification,
but was removed before any full releases. Since variables can now be
larger than a single page, sysfs isn't the best interface for this. So,
instead, let's add a filesystem. Variables can be read, written and
created, with the first 4 bytes of each variable representing its UEFI
attributes. The create() method doesn't actually commit to flash since
zero-length variables can't exist per-spec.

Updates from Jeremy Kerr <jeremy.kerr@canonical.com>.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 384 ++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/efi.h        |   5 +
 2 files changed, 383 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index d10c987..b605c48 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -80,6 +80,10 @@
 #include <linux/slab.h>
 #include <linux/pstore.h>
 
+#include <linux/fs.h>
+#include <linux/ramfs.h>
+#include <linux/pagemap.h>
+
 #include <asm/uaccess.h>
 
 #define EFIVARS_VERSION "0.08"
@@ -91,6 +95,7 @@ MODULE_LICENSE("GPL");
 MODULE_VERSION(EFIVARS_VERSION);
 
 #define DUMP_NAME_LEN 52
+#define GUID_LEN 37
 
 /*
  * The maximum size of VariableName + Data = 1024
@@ -108,7 +113,6 @@ struct efi_variable {
 	__u32         Attributes;
 } __attribute__((packed));
 
-
 struct efivar_entry {
 	struct efivars *efivars;
 	struct efi_variable var;
@@ -122,6 +126,9 @@ struct efivar_attribute {
 	ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
 };
 
+static struct efivars __efivars;
+static struct efivar_operations ops;
+
 #define PSTORE_EFI_ATTRIBUTES \
 	(EFI_VARIABLE_NON_VOLATILE | \
 	 EFI_VARIABLE_BOOTSERVICE_ACCESS | \
@@ -629,14 +636,380 @@ static struct kobj_type efivar_ktype = {
 	.default_attrs = def_attrs,
 };
 
-static struct pstore_info efi_pstore_info;
-
 static inline void
 efivar_unregister(struct efivar_entry *var)
 {
 	kobject_put(&var->kobj);
 }
 
+static int efivarfs_file_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	return 0;
+}
+
+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;
+	struct efivars *efivars;
+	efi_status_t status;
+	void *data;
+	u32 attributes;
+	struct inode *inode = file->f_mapping->host;
+	int datasize = count - sizeof(attributes);
+
+	if (count < sizeof(attributes))
+		return -EINVAL;
+
+	data = kmalloc(datasize, GFP_KERNEL);
+
+	if (!data)
+		return -ENOMEM;
+
+	efivars = var->efivars;
+
+	if (copy_from_user(&attributes, userbuf, sizeof(attributes))) {
+		count = -EFAULT;
+		goto out;
+	}
+
+	if (attributes & ~(EFI_VARIABLE_MASK)) {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (copy_from_user(data, userbuf + sizeof(attributes), datasize)) {
+		count = -EFAULT;
+		goto out;
+	}
+
+	if (validate_var(&var->var, data, datasize) == false) {
+		count = -EINVAL;
+		goto out;
+	}
+
+	status = efivars->ops->set_variable(var->var.VariableName,
+					    &var->var.VendorGuid,
+					    attributes, datasize,
+					    data);
+
+	switch (status) {
+	case EFI_SUCCESS:
+		mutex_lock(&inode->i_mutex);
+		i_size_write(inode, count);
+		mutex_unlock(&inode->i_mutex);
+		break;
+	case EFI_INVALID_PARAMETER:
+		count = -EINVAL;
+		break;
+	case EFI_OUT_OF_RESOURCES:
+		count = -ENOSPC;
+		break;
+	case EFI_DEVICE_ERROR:
+		count = -EIO;
+		break;
+	case EFI_WRITE_PROTECTED:
+		count = -EROFS;
+		break;
+	case EFI_SECURITY_VIOLATION:
+		count = -EACCES;
+		break;
+	case EFI_NOT_FOUND:
+		count = -ENOENT;
+		break;
+	default:
+		count = -EINVAL;
+		break;
+	}
+out:
+	kfree(data);
+
+	return count;
+}
+
+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;
+	struct efivars *efivars = var->efivars;
+	efi_status_t status;
+	unsigned long datasize = 0;
+	u32 attributes;
+	void *data;
+	ssize_t size;
+
+	status = efivars->ops->get_variable(var->var.VariableName,
+					    &var->var.VendorGuid,
+					    &attributes, &datasize, NULL);
+
+	if (status != EFI_BUFFER_TOO_SMALL)
+		return 0;
+
+	data = kmalloc(datasize + 4, GFP_KERNEL);
+
+	if (!data)
+		return 0;
+
+	status = efivars->ops->get_variable(var->var.VariableName,
+					    &var->var.VendorGuid,
+					    &attributes, &datasize,
+					    (data + 4));
+
+	if (status != EFI_SUCCESS)
+		return 0;
+
+	memcpy(data, &attributes, 4);
+	size = simple_read_from_buffer(userbuf, count, ppos,
+					data, datasize + 4);
+	kfree(data);
+
+	return size;
+}
+
+static void efivarfs_evict_inode(struct inode *inode)
+{
+	clear_inode(inode);
+}
+
+static const struct super_operations efivarfs_ops = {
+	.statfs = simple_statfs,
+	.drop_inode = generic_delete_inode,
+	.evict_inode = efivarfs_evict_inode,
+	.show_options = generic_show_options,
+};
+
+static struct super_block *efivarfs_sb;
+
+static const struct inode_operations efivarfs_dir_inode_operations;
+
+static const struct file_operations efivarfs_file_operations = {
+	.open	= efivarfs_file_open,
+	.read	= efivarfs_file_read,
+	.write	= efivarfs_file_write,
+	.llseek	= no_llseek,
+};
+
+static struct inode *efivarfs_get_inode(struct super_block *sb,
+				const struct inode *dir, int mode, dev_t dev)
+{
+	struct inode *inode = new_inode(sb);
+
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		inode->i_uid = inode->i_gid = 0;
+		inode->i_mode = mode;
+		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+		switch (mode & S_IFMT) {
+		case S_IFREG:
+			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;
+}
+
+static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
+{
+	guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]);
+	guid->b[1] = hex_to_bin(str[4]) << 4 | hex_to_bin(str[5]);
+	guid->b[2] = hex_to_bin(str[2]) << 4 | hex_to_bin(str[3]);
+	guid->b[3] = hex_to_bin(str[0]) << 4 | hex_to_bin(str[1]);
+	guid->b[4] = hex_to_bin(str[11]) << 4 | hex_to_bin(str[12]);
+	guid->b[5] = hex_to_bin(str[9]) << 4 | hex_to_bin(str[10]);
+	guid->b[6] = hex_to_bin(str[16]) << 4 | hex_to_bin(str[17]);
+	guid->b[7] = hex_to_bin(str[14]) << 4 | hex_to_bin(str[15]);
+	guid->b[8] = hex_to_bin(str[19]) << 4 | hex_to_bin(str[20]);
+	guid->b[9] = hex_to_bin(str[21]) << 4 | hex_to_bin(str[22]);
+	guid->b[10] = hex_to_bin(str[24]) << 4 | hex_to_bin(str[25]);
+	guid->b[11] = hex_to_bin(str[26]) << 4 | hex_to_bin(str[27]);
+	guid->b[12] = hex_to_bin(str[28]) << 4 | hex_to_bin(str[29]);
+	guid->b[13] = hex_to_bin(str[30]) << 4 | hex_to_bin(str[31]);
+	guid->b[14] = hex_to_bin(str[32]) << 4 | hex_to_bin(str[33]);
+	guid->b[15] = hex_to_bin(str[34]) << 4 | hex_to_bin(str[35]);
+}
+
+static int efivarfs_create(struct inode *dir, struct dentry *dentry,
+			  umode_t mode, bool excl)
+{
+	struct inode *inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
+	struct efivars *efivars = &__efivars;
+	struct efivar_entry *var;
+	int namelen, i = 0, err = 0;
+
+	if (dentry->d_name.len < 38)
+		return -EINVAL;
+
+	if (!inode)
+		return -ENOSPC;
+
+	var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
+
+	if (!var)
+		return -ENOMEM;
+
+	namelen = dentry->d_name.len - GUID_LEN;
+
+	efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1,
+			&var->var.VendorGuid);
+
+	for (i = 0; i < namelen; i++)
+		var->var.VariableName[i] = dentry->d_name.name[i];
+
+	var->var.VariableName[i] = '\0';
+
+	inode->i_private = var;
+	var->efivars = efivars;
+	var->kobj.kset = efivars->kset;
+
+	err = kobject_init_and_add(&var->kobj, &efivar_ktype, NULL, "%s",
+			     dentry->d_name.name);
+	if (err)
+		goto out;
+
+	kobject_uevent(&var->kobj, KOBJ_ADD);
+	spin_lock(&efivars->lock);
+	list_add(&var->list, &efivars->list);
+	spin_unlock(&efivars->lock);
+	d_instantiate(dentry, inode);
+	dget(dentry);
+out:
+	if (err)
+		kfree(var);
+	return err;
+}
+
+static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct efivar_entry *var = dentry->d_inode->i_private;
+	struct efivars *efivars = var->efivars;
+	efi_status_t status;
+
+	spin_lock(&efivars->lock);
+
+	status = efivars->ops->set_variable(var->var.VariableName,
+					    &var->var.VendorGuid,
+					    0, 0, NULL);
+
+	if (status == EFI_SUCCESS || status == EFI_NOT_FOUND) {
+		list_del(&var->list);
+		spin_unlock(&efivars->lock);
+		efivar_unregister(var);
+		drop_nlink(dir);
+		dput(dentry);
+		return 0;
+	}
+
+	spin_unlock(&efivars->lock);
+	return -EINVAL;
+};
+
+int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode = NULL;
+	struct dentry *root;
+	struct efivar_entry *entry, *n;
+	struct efivars *efivars = &__efivars;
+	int err;
+
+	efivarfs_sb = sb;
+
+	sb->s_maxbytes          = MAX_LFS_FILESIZE;
+	sb->s_blocksize         = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
+	sb->s_magic             = PSTOREFS_MAGIC;
+	sb->s_op                = &efivarfs_ops;
+	sb->s_time_gran         = 1;
+
+	inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
+	if (!inode) {
+		err = -ENOMEM;
+		goto fail;
+	}
+	inode->i_op = &efivarfs_dir_inode_operations;
+
+	root = d_make_root(inode);
+	sb->s_root = root;
+	if (!root) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
+	list_for_each_entry_safe(entry, n, &efivars->list, list) {
+		struct inode *inode;
+		struct dentry *dentry, *root = efivarfs_sb->s_root;
+		char *name;
+		unsigned long size = 0;
+		int len, i;
+
+		len = utf16_strlen(entry->var.VariableName);
+
+		/* GUID plus trailing NULL */
+		name = kmalloc(len + 38, GFP_ATOMIC);
+
+		for (i = 0; i < len; i++)
+			name[i] = entry->var.VariableName[i] & 0xFF;
+
+		name[len] = '-';
+
+		efi_guid_unparse(&entry->var.VendorGuid, name + len + 1);
+
+		name[len+GUID_LEN] = '\0';
+
+		inode = efivarfs_get_inode(efivarfs_sb, root->d_inode,
+					  S_IFREG | 0644, 0);
+		dentry = d_alloc_name(root, name);
+
+		efivars->ops->get_variable(entry->var.VariableName,
+					   &entry->var.VendorGuid,
+					   &entry->var.Attributes,
+					   &size,
+					   NULL);
+
+		mutex_lock(&inode->i_mutex);
+		inode->i_private = entry;
+		i_size_write(inode, size+4);
+		mutex_unlock(&inode->i_mutex);
+		d_add(dentry, inode);
+	}
+
+	return 0;
+fail:
+	iput(inode);
+	return err;
+}
+
+static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
+				    int flags, const char *dev_name, void *data)
+{
+	return mount_single(fs_type, flags, data, efivarfs_fill_super);
+}
+
+static void efivarfs_kill_sb(struct super_block *sb)
+{
+	kill_litter_super(sb);
+	efivarfs_sb = NULL;
+}
+
+static struct file_system_type efivarfs_type = {
+	.name    = "efivarfs",
+	.mount   = efivarfs_mount,
+	.kill_sb = efivarfs_kill_sb,
+};
+
+static const struct inode_operations efivarfs_dir_inode_operations = {
+	.lookup = simple_lookup,
+	.unlink = efivarfs_unlink,
+	.create = efivarfs_create,
+};
+
+static struct pstore_info efi_pstore_info;
+
 #ifdef CONFIG_PSTORE
 
 static int efi_pstore_open(struct pstore_info *psi)
@@ -1198,6 +1571,8 @@ int register_efivars(struct efivars *efivars,
 		pstore_register(&efivars->efi_pstore_info);
 	}
 
+	register_filesystem(&efivarfs_type);
+
 out:
 	kfree(variable_name);
 
@@ -1205,9 +1580,6 @@ out:
 }
 EXPORT_SYMBOL_GPL(register_efivars);
 
-static struct efivars __efivars;
-static struct efivar_operations ops;
-
 /*
  * For now we register the efi subsystem with the firmware subsystem
  * and the vars subsystem with the efi subsystem.  In the future, it
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 5782114..2f1db28 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -29,7 +29,12 @@
 #define EFI_UNSUPPORTED		( 3 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_BAD_BUFFER_SIZE     ( 4 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_BUFFER_TOO_SMALL	( 5 | (1UL << (BITS_PER_LONG-1)))
+#define EFI_NOT_READY		( 6 | (1UL << (BITS_PER_LONG-1)))
+#define EFI_DEVICE_ERROR	( 7 | (1UL << (BITS_PER_LONG-1)))
+#define EFI_WRITE_PROTECTED	( 8 | (1UL << (BITS_PER_LONG-1)))
+#define EFI_OUT_OF_RESOURCES	( 9 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_NOT_FOUND		(14 | (1UL << (BITS_PER_LONG-1)))
+#define EFI_SECURITY_VIOLATION	(26 | (1UL << (BITS_PER_LONG-1)))
 
 typedef unsigned long efi_status_t;
 typedef u8 efi_bool_t;
-- 
1.7.12.1


From 47c7d712bac1ba86ae9d3f8bb5594d8d9ab57537 Mon Sep 17 00:00:00 2001
From: Jeremy Kerr <jeremy.kerr@canonical.com>
Date: Fri, 5 Oct 2012 13:54:56 +0800
Subject: [PATCH 02/17] efi: Handle deletions and size changes in
 efivarfs_write_file

A write to an efivarfs file will not always result in a variable of
'count' size after the EFI SetVariable() call. We may have appended to
the existing data (ie, with the EFI_VARIABLE_APPEND_WRITE attribute), or
even have deleted the variable (with an authenticated variable update,
with a zero datasize).

This change re-reads the updated variable from firmware, to check for
size changes and deletions. In the latter case, we need to drop the
dentry.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 49 ++++++++++++++++++++++++++++++++++++----------
 1 file changed, 39 insertions(+), 10 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index b605c48..d7658b4 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -658,6 +658,7 @@ static ssize_t efivarfs_file_write(struct file *file,
 	u32 attributes;
 	struct inode *inode = file->f_mapping->host;
 	int datasize = count - sizeof(attributes);
+	unsigned long newdatasize;
 
 	if (count < sizeof(attributes))
 		return -EINVAL;
@@ -696,32 +697,60 @@ static ssize_t efivarfs_file_write(struct file *file,
 
 	switch (status) {
 	case EFI_SUCCESS:
-		mutex_lock(&inode->i_mutex);
-		i_size_write(inode, count);
-		mutex_unlock(&inode->i_mutex);
 		break;
 	case EFI_INVALID_PARAMETER:
 		count = -EINVAL;
-		break;
+		goto out;
 	case EFI_OUT_OF_RESOURCES:
 		count = -ENOSPC;
-		break;
+		goto out;
 	case EFI_DEVICE_ERROR:
 		count = -EIO;
-		break;
+		goto out;
 	case EFI_WRITE_PROTECTED:
 		count = -EROFS;
-		break;
+		goto out;
 	case EFI_SECURITY_VIOLATION:
 		count = -EACCES;
-		break;
+		goto out;
 	case EFI_NOT_FOUND:
 		count = -ENOENT;
-		break;
+		goto out;
 	default:
 		count = -EINVAL;
-		break;
+		goto out;
 	}
+
+	/*
+	 * 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.
+	 */
+	newdatasize = 0;
+	status = efivars->ops->get_variable(var->var.VariableName,
+					    &var->var.VendorGuid,
+					    NULL, &newdatasize,
+					    NULL);
+
+	if (status == EFI_BUFFER_TOO_SMALL) {
+		mutex_lock(&inode->i_mutex);
+		i_size_write(inode, newdatasize + sizeof(attributes));
+		mutex_unlock(&inode->i_mutex);
+
+	} else if (status == EFI_NOT_FOUND) {
+		spin_lock(&efivars->lock);
+		list_del(&var->list);
+		spin_unlock(&efivars->lock);
+		efivar_unregister(var);
+		drop_nlink(inode);
+		dput(file->f_dentry);
+
+	} else {
+		pr_warn("efivarfs: inconsistent EFI variable implementation? "
+				"status = %lx\n", status);
+	}
+
 out:
 	kfree(data);
 
-- 
1.7.12.1


From 48173c3d1e7014574d5b2517a471587775e4cb91 Mon Sep 17 00:00:00 2001
From: "Lee, Chun-Yi" <joeyli.kernel@gmail.com>
Date: Fri, 5 Oct 2012 13:54:56 +0800
Subject: [PATCH 03/17] efi: add efivars kobject to efi sysfs folder

UEFI variable filesystem need a new mount point, so this patch add
efivars kobject to efi_kobj for create a /sys/firmware/efi/efivars
folder.

Cc: Matthew Garrett <mjg@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 9 +++++++++
 include/linux/efi.h        | 1 +
 2 files changed, 10 insertions(+)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index d7658b4..6793965 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -1527,6 +1527,7 @@ void unregister_efivars(struct efivars *efivars)
 		sysfs_remove_bin_file(&efivars->kset->kobj, efivars->del_var);
 	kfree(efivars->new_var);
 	kfree(efivars->del_var);
+	kobject_put(efivars->kobject);
 	kset_unregister(efivars->kset);
 }
 EXPORT_SYMBOL_GPL(unregister_efivars);
@@ -1558,6 +1559,14 @@ int register_efivars(struct efivars *efivars,
 		goto out;
 	}
 
+	efivars->kobject = kobject_create_and_add("efivars", parent_kobj);
+	if (!efivars->kobject) {
+		pr_err("efivars: Subsystem registration failed.\n");
+		error = -ENOMEM;
+		kset_unregister(efivars->kset);
+		goto out;
+	}
+
 	/*
 	 * Per EFI spec, the maximum storage allocated for both
 	 * the variable name and variable data is 1024 bytes.
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 2f1db28..bff4b5e 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -659,6 +659,7 @@ struct efivars {
 	spinlock_t lock;
 	struct list_head list;
 	struct kset *kset;
+	struct kobject *kobject;
 	struct bin_attribute *new_var, *del_var;
 	const struct efivar_operations *ops;
 	struct efivar_entry *walk_entry;
-- 
1.7.12.1


From 8c209f22c606ba8c4fa939245efae9921fb1988a Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Thu, 4 Oct 2012 09:57:31 +0100
Subject: [PATCH 04/17] efivarfs: Add documentation for the EFI variable
 filesystem

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 Documentation/filesystems/00-INDEX     |  2 ++
 Documentation/filesystems/efivarfs.txt | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)
 create mode 100644 Documentation/filesystems/efivarfs.txt

diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX
index 8c624a1..7b52ba7 100644
--- a/Documentation/filesystems/00-INDEX
+++ b/Documentation/filesystems/00-INDEX
@@ -38,6 +38,8 @@ dnotify_test.c
 	- example program for dnotify
 ecryptfs.txt
 	- docs on eCryptfs: stacked cryptographic filesystem for Linux.
+efivarfs.txt
+	- info for the efivarfs filesystem.
 exofs.txt
 	- info, usage, mount options, design about EXOFS.
 ext2.txt
diff --git a/Documentation/filesystems/efivarfs.txt b/Documentation/filesystems/efivarfs.txt
new file mode 100644
index 0000000..c477af0
--- /dev/null
+++ b/Documentation/filesystems/efivarfs.txt
@@ -0,0 +1,16 @@
+
+efivarfs - a (U)EFI variable filesystem
+
+The efivarfs filesystem was created to address the shortcomings of
+using entries in sysfs to maintain EFI variables. The old sysfs EFI
+variables code only supported variables of up to 1024 bytes. This
+limitation existed in version 0.99 of the EFI specification, but was
+removed before any full releases. Since variables can now be larger
+than a single page, sysfs isn't the best interface for this.
+
+Variables can be created, deleted and modified with the efivarfs
+filesystem.
+
+efivarfs is typically mounted like this,
+
+	mount -t efivarfs none /sys/firmware/efi/efivars
-- 
1.7.12.1


From 5897a97e56e999e3fe1d5b9d018496f2656f33fb Mon Sep 17 00:00:00 2001
From: Andy Whitcroft <apw@canonical.com>
Date: Thu, 11 Oct 2012 11:32:17 +0100
Subject: [PATCH 05/17] efivarfs: efivarfs_file_read ensure we free data in
 error paths

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 6793965..b7c9a32 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -766,7 +766,7 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	unsigned long datasize = 0;
 	u32 attributes;
 	void *data;
-	ssize_t size;
+	ssize_t size = 0;
 
 	status = efivars->ops->get_variable(var->var.VariableName,
 					    &var->var.VendorGuid,
@@ -784,13 +784,13 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 					    &var->var.VendorGuid,
 					    &attributes, &datasize,
 					    (data + 4));
-
 	if (status != EFI_SUCCESS)
-		return 0;
+		goto out_free;
 
 	memcpy(data, &attributes, 4);
 	size = simple_read_from_buffer(userbuf, count, ppos,
 					data, datasize + 4);
+out_free:
 	kfree(data);
 
 	return size;
-- 
1.7.12.1


From e1f15611b82a3137949ec11b09a7c1230eec1b8e Mon Sep 17 00:00:00 2001
From: Andy Whitcroft <apw@canonical.com>
Date: Thu, 11 Oct 2012 11:32:18 +0100
Subject: [PATCH 06/17] efivarfs: efivarfs_create() ensure we drop our
 reference on inode on error

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index b7c9a32..6e5f367 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -866,7 +866,7 @@ static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
 static int efivarfs_create(struct inode *dir, struct dentry *dentry,
 			  umode_t mode, bool excl)
 {
-	struct inode *inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
+	struct inode *inode;
 	struct efivars *efivars = &__efivars;
 	struct efivar_entry *var;
 	int namelen, i = 0, err = 0;
@@ -874,13 +874,15 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
 	if (dentry->d_name.len < 38)
 		return -EINVAL;
 
+	inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
 	if (!inode)
 		return -ENOSPC;
 
 	var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
-
-	if (!var)
-		return -ENOMEM;
+	if (!var) {
+		err = -ENOMEM;
+		goto out;
+	}
 
 	namelen = dentry->d_name.len - GUID_LEN;
 
@@ -908,8 +910,10 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
 	d_instantiate(dentry, inode);
 	dget(dentry);
 out:
-	if (err)
+	if (err) {
 		kfree(var);
+		iput(inode);
+	}
 	return err;
 }
 
-- 
1.7.12.1


From da03533239fd31112b355b2e1c1b8aa168a27440 Mon Sep 17 00:00:00 2001
From: Andy Whitcroft <apw@canonical.com>
Date: Thu, 11 Oct 2012 11:32:19 +0100
Subject: [PATCH 07/17] efivarfs: efivarfs_fill_super() fix inode reference
 counts

When d_make_root() fails it will automatically drop the reference
on the root inode.  We should not be doing so as well.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 6e5f367..adfc486 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -948,7 +948,6 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	struct dentry *root;
 	struct efivar_entry *entry, *n;
 	struct efivars *efivars = &__efivars;
-	int err;
 
 	efivarfs_sb = sb;
 
@@ -960,18 +959,14 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_time_gran         = 1;
 
 	inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
-	if (!inode) {
-		err = -ENOMEM;
-		goto fail;
-	}
+	if (!inode)
+		return -ENOMEM;
 	inode->i_op = &efivarfs_dir_inode_operations;
 
 	root = d_make_root(inode);
 	sb->s_root = root;
-	if (!root) {
-		err = -ENOMEM;
-		goto fail;
-	}
+	if (!root)
+		return -ENOMEM;
 
 	list_for_each_entry_safe(entry, n, &efivars->list, list) {
 		struct inode *inode;
@@ -1012,9 +1007,6 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	}
 
 	return 0;
-fail:
-	iput(inode);
-	return err;
 }
 
 static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
-- 
1.7.12.1


From 2e2b7d34a6b3b4534165d5cc22705b3c60e48f0a Mon Sep 17 00:00:00 2001
From: Andy Whitcroft <apw@canonical.com>
Date: Thu, 11 Oct 2012 11:32:20 +0100
Subject: [PATCH 08/17] efivarfs: efivarfs_fill_super() ensure we free our
 temporary name

d_alloc_name() copies the passed name to new storage, once complete we
no longer need our name.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index adfc486..36b3dd6 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -992,6 +992,8 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 		inode = efivarfs_get_inode(efivarfs_sb, root->d_inode,
 					  S_IFREG | 0644, 0);
 		dentry = d_alloc_name(root, name);
+		/* copied by the above to local storage in the dentry. */
+		kfree(name);
 
 		efivars->ops->get_variable(entry->var.VariableName,
 					   &entry->var.VendorGuid,
-- 
1.7.12.1


From 247fd819a9fa1920ed7149bdbe13a16beb0ad44f Mon Sep 17 00:00:00 2001
From: Andy Whitcroft <apw@canonical.com>
Date: Thu, 11 Oct 2012 11:32:21 +0100
Subject: [PATCH 09/17] efivarfs: efivarfs_fill_super() ensure we clean up
 correctly on error

Ensure we free both the name and inode on error when building the
individual variables.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 36b3dd6..216086d 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -948,6 +948,7 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	struct dentry *root;
 	struct efivar_entry *entry, *n;
 	struct efivars *efivars = &__efivars;
+	char *name;
 
 	efivarfs_sb = sb;
 
@@ -969,16 +970,18 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 		return -ENOMEM;
 
 	list_for_each_entry_safe(entry, n, &efivars->list, list) {
-		struct inode *inode;
 		struct dentry *dentry, *root = efivarfs_sb->s_root;
-		char *name;
 		unsigned long size = 0;
 		int len, i;
 
+		inode = NULL;
+
 		len = utf16_strlen(entry->var.VariableName);
 
 		/* GUID plus trailing NULL */
 		name = kmalloc(len + 38, GFP_ATOMIC);
+		if (!name)
+			goto fail;
 
 		for (i = 0; i < len; i++)
 			name[i] = entry->var.VariableName[i] & 0xFF;
@@ -991,7 +994,13 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 
 		inode = efivarfs_get_inode(efivarfs_sb, root->d_inode,
 					  S_IFREG | 0644, 0);
+		if (!inode)
+			goto fail_name;
+
 		dentry = d_alloc_name(root, name);
+		if (!dentry)
+			goto fail_inode;
+
 		/* copied by the above to local storage in the dentry. */
 		kfree(name);
 
@@ -1009,6 +1018,13 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	}
 
 	return 0;
+
+fail_inode:
+	iput(inode);
+fail_name:
+	kfree(name);
+fail:
+	return -ENOMEM;
 }
 
 static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
-- 
1.7.12.1


From 01eb8510eb659fd1471d92166bfd7a4d939b2b21 Mon Sep 17 00:00:00 2001
From: Jeremy Kerr <jeremy.kerr@canonical.com>
Date: Thu, 11 Oct 2012 21:19:11 +0800
Subject: [PATCH 10/17] efivarfs: Implement exclusive access for
 {get,set}_variable

Currently, efivarfs does not enforce exclusion over the get_variable and
set_variable operations. Section 7.1 of UEFI requires us to only allow a
single processor to enter {get,set}_variable services at once.

This change acquires the efivars->lock over calls to these operations
from the efivarfs paths.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 68 +++++++++++++++++++++++++++++-----------------
 1 file changed, 43 insertions(+), 25 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 216086d..d478c56 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -690,35 +690,45 @@ static ssize_t efivarfs_file_write(struct file *file,
 		goto out;
 	}
 
+	/*
+	 * The lock here protects the get_variable call, the conditional
+	 * set_variable call, and removal of the variable from the efivars
+	 * list (in the case of an authenticated delete).
+	 */
+	spin_lock(&efivars->lock);
+
 	status = efivars->ops->set_variable(var->var.VariableName,
 					    &var->var.VendorGuid,
 					    attributes, datasize,
 					    data);
 
-	switch (status) {
-	case EFI_SUCCESS:
-		break;
-	case EFI_INVALID_PARAMETER:
-		count = -EINVAL;
-		goto out;
-	case EFI_OUT_OF_RESOURCES:
-		count = -ENOSPC;
-		goto out;
-	case EFI_DEVICE_ERROR:
-		count = -EIO;
-		goto out;
-	case EFI_WRITE_PROTECTED:
-		count = -EROFS;
-		goto out;
-	case EFI_SECURITY_VIOLATION:
-		count = -EACCES;
-		goto out;
-	case EFI_NOT_FOUND:
-		count = -ENOENT;
-		goto out;
-	default:
-		count = -EINVAL;
-		goto out;
+	if (status != EFI_SUCCESS) {
+		spin_unlock(&efivars->lock);
+		kfree(data);
+
+		switch (status) {
+		case EFI_INVALID_PARAMETER:
+			count = -EINVAL;
+			break;
+		case EFI_OUT_OF_RESOURCES:
+			count = -ENOSPC;
+			break;
+		case EFI_DEVICE_ERROR:
+			count = -EIO;
+			break;
+		case EFI_WRITE_PROTECTED:
+			count = -EROFS;
+			break;
+		case EFI_SECURITY_VIOLATION:
+			count = -EACCES;
+			break;
+		case EFI_NOT_FOUND:
+			count = -ENOENT;
+			break;
+		default:
+			count = -EINVAL;
+		}
+		return count;
 	}
 
 	/*
@@ -734,12 +744,12 @@ static ssize_t efivarfs_file_write(struct file *file,
 					    NULL);
 
 	if (status == EFI_BUFFER_TOO_SMALL) {
+		spin_unlock(&efivars->lock);
 		mutex_lock(&inode->i_mutex);
 		i_size_write(inode, newdatasize + sizeof(attributes));
 		mutex_unlock(&inode->i_mutex);
 
 	} else if (status == EFI_NOT_FOUND) {
-		spin_lock(&efivars->lock);
 		list_del(&var->list);
 		spin_unlock(&efivars->lock);
 		efivar_unregister(var);
@@ -747,6 +757,7 @@ static ssize_t efivarfs_file_write(struct file *file,
 		dput(file->f_dentry);
 
 	} else {
+		spin_unlock(&efivars->lock);
 		pr_warn("efivarfs: inconsistent EFI variable implementation? "
 				"status = %lx\n", status);
 	}
@@ -768,9 +779,11 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	void *data;
 	ssize_t size = 0;
 
+	spin_lock(&efivars->lock);
 	status = efivars->ops->get_variable(var->var.VariableName,
 					    &var->var.VendorGuid,
 					    &attributes, &datasize, NULL);
+	spin_unlock(&efivars->lock);
 
 	if (status != EFI_BUFFER_TOO_SMALL)
 		return 0;
@@ -780,10 +793,13 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	if (!data)
 		return 0;
 
+	spin_lock(&efivars->lock);
 	status = efivars->ops->get_variable(var->var.VariableName,
 					    &var->var.VendorGuid,
 					    &attributes, &datasize,
 					    (data + 4));
+	spin_unlock(&efivars->lock);
+
 	if (status != EFI_SUCCESS)
 		goto out_free;
 
@@ -1004,11 +1020,13 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 		/* copied by the above to local storage in the dentry. */
 		kfree(name);
 
+		spin_lock(&efivars->lock);
 		efivars->ops->get_variable(entry->var.VariableName,
 					   &entry->var.VendorGuid,
 					   &entry->var.Attributes,
 					   &size,
 					   NULL);
+		spin_unlock(&efivars->lock);
 
 		mutex_lock(&inode->i_mutex);
 		inode->i_private = entry;
-- 
1.7.12.1


From 871a36dd8509c2833d02930d6f166a65f85c4f92 Mon Sep 17 00:00:00 2001
From: Jeremy Kerr <jeremy.kerr@canonical.com>
Date: Fri, 19 Oct 2012 15:16:45 +0800
Subject: [PATCH 11/17] efi: Clarify GUID length calculations

At present, the handling of GUIDs in efivar file names isn't consistent.
We use GUID_LEN in some places, and 38 in others (GUID_LEN plus
separator), and implicitly use the presence of the trailing NUL.

This change removes the trailing NUL from GUID_LEN, so that we're
explicitly adding it when required. We also replace magic numbers
with GUID_LEN, and clarify the comments where appropriate.

We also fix the allocation size in efivar_create_sysfs_entry, where
we're allocating one byte too much, due to counting the trailing NUL
twice - once when calculating short_name_size, and once in the kzalloc.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 33 +++++++++++++++++++++++++--------
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index d478c56..a93e401 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -95,7 +95,12 @@ MODULE_LICENSE("GPL");
 MODULE_VERSION(EFIVARS_VERSION);
 
 #define DUMP_NAME_LEN 52
-#define GUID_LEN 37
+
+/*
+ * Length of a GUID string (strlen("aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee"))
+ * not including trailing NUL
+ */
+#define GUID_LEN 36
 
 /*
  * The maximum size of VariableName + Data = 1024
@@ -887,7 +892,11 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
 	struct efivar_entry *var;
 	int namelen, i = 0, err = 0;
 
-	if (dentry->d_name.len < 38)
+	/*
+	 * We need a GUID, plus at least one letter for the variable name,
+	 * plus the '-' separator
+	 */
+	if (dentry->d_name.len < GUID_LEN + 2)
 		return -EINVAL;
 
 	inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
@@ -900,7 +909,8 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
 		goto out;
 	}
 
-	namelen = dentry->d_name.len - GUID_LEN;
+	/* length of the variable name itself: remove GUID and separator */
+	namelen = dentry->d_name.len - GUID_LEN - 1;
 
 	efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1,
 			&var->var.VendorGuid);
@@ -994,8 +1004,8 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 
 		len = utf16_strlen(entry->var.VariableName);
 
-		/* GUID plus trailing NULL */
-		name = kmalloc(len + 38, GFP_ATOMIC);
+		/* name, plus '-', plus GUID, plus NUL*/
+		name = kmalloc(len + 1 + GUID_LEN + 1, GFP_ATOMIC);
 		if (!name)
 			goto fail;
 
@@ -1006,7 +1016,7 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 
 		efi_guid_unparse(&entry->var.VendorGuid, name + len + 1);
 
-		name[len+GUID_LEN] = '\0';
+		name[len+GUID_LEN+1] = '\0';
 
 		inode = efivarfs_get_inode(efivarfs_sb, root->d_inode,
 					  S_IFREG | 0644, 0);
@@ -1435,11 +1445,18 @@ efivar_create_sysfs_entry(struct efivars *efivars,
 			  efi_char16_t *variable_name,
 			  efi_guid_t *vendor_guid)
 {
-	int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
+	int i, short_name_size;
 	char *short_name;
 	struct efivar_entry *new_efivar;
 
-	short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
+	/*
+	 * Length of the variable bytes in ASCII, plus the '-' separator,
+	 * plus the GUID, plus trailing NUL
+	 */
+	short_name_size = variable_name_size / sizeof(efi_char16_t)
+				+ 1 + GUID_LEN + 1;
+
+	short_name = kzalloc(short_name_size, GFP_KERNEL);
 	new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
 
 	if (!short_name || !new_efivar)  {
-- 
1.7.12.1


From 5d2cf34731c10e035387ae65f6cf461fd7a53304 Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Tue, 16 Oct 2012 15:58:07 +0100
Subject: [PATCH 12/17] efivarfs: Return an error if we fail to read a
 variable

Instead of always returning 0 in efivarfs_file_read(), even when we
fail to successfully read the variable, convert the EFI status to
something meaningful and return that to the caller. This way the user
will have some hint as to why the read failed.

Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 62 +++++++++++++++++++++++++++-------------------
 1 file changed, 36 insertions(+), 26 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index a93e401..277e426 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -653,6 +653,36 @@ static int efivarfs_file_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static int efi_status_to_err(efi_status_t status)
+{
+	int err;
+
+	switch (status) {
+	case EFI_INVALID_PARAMETER:
+		err = -EINVAL;
+		break;
+	case EFI_OUT_OF_RESOURCES:
+		err = -ENOSPC;
+		break;
+	case EFI_DEVICE_ERROR:
+		err = -EIO;
+		break;
+	case EFI_WRITE_PROTECTED:
+		err = -EROFS;
+		break;
+	case EFI_SECURITY_VIOLATION:
+		err = -EACCES;
+		break;
+	case EFI_NOT_FOUND:
+		err = -ENOENT;
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
 static ssize_t efivarfs_file_write(struct file *file,
 		const char __user *userbuf, size_t count, loff_t *ppos)
 {
@@ -711,29 +741,7 @@ static ssize_t efivarfs_file_write(struct file *file,
 		spin_unlock(&efivars->lock);
 		kfree(data);
 
-		switch (status) {
-		case EFI_INVALID_PARAMETER:
-			count = -EINVAL;
-			break;
-		case EFI_OUT_OF_RESOURCES:
-			count = -ENOSPC;
-			break;
-		case EFI_DEVICE_ERROR:
-			count = -EIO;
-			break;
-		case EFI_WRITE_PROTECTED:
-			count = -EROFS;
-			break;
-		case EFI_SECURITY_VIOLATION:
-			count = -EACCES;
-			break;
-		case EFI_NOT_FOUND:
-			count = -ENOENT;
-			break;
-		default:
-			count = -EINVAL;
-		}
-		return count;
+		return efi_status_to_err(status);
 	}
 
 	/*
@@ -791,12 +799,12 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	spin_unlock(&efivars->lock);
 
 	if (status != EFI_BUFFER_TOO_SMALL)
-		return 0;
+		return efi_status_to_err(status);
 
 	data = kmalloc(datasize + 4, GFP_KERNEL);
 
 	if (!data)
-		return 0;
+		return -ENOMEM;
 
 	spin_lock(&efivars->lock);
 	status = efivars->ops->get_variable(var->var.VariableName,
@@ -805,8 +813,10 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 					    (data + 4));
 	spin_unlock(&efivars->lock);
 
-	if (status != EFI_SUCCESS)
+	if (status != EFI_SUCCESS) {
+		size = efi_status_to_err(status);
 		goto out_free;
+	}
 
 	memcpy(data, &attributes, 4);
 	size = simple_read_from_buffer(userbuf, count, ppos,
-- 
1.7.12.1


From 0bdf9e5f271f74b7079d8bd06aea7973ffa43562 Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Mon, 22 Oct 2012 15:23:29 +0100
Subject: [PATCH 13/17] efivarfs: Replace magic number with sizeof(attributes)

Seeing "+ 4" littered throughout the functions gets a bit
confusing. Use "sizeof(attributes)" which clearly explains what
quantity we're adding.

Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 277e426..2c04434 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -801,7 +801,7 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	if (status != EFI_BUFFER_TOO_SMALL)
 		return efi_status_to_err(status);
 
-	data = kmalloc(datasize + 4, GFP_KERNEL);
+	data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
 
 	if (!data)
 		return -ENOMEM;
@@ -810,7 +810,7 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	status = efivars->ops->get_variable(var->var.VariableName,
 					    &var->var.VendorGuid,
 					    &attributes, &datasize,
-					    (data + 4));
+					    (data + sizeof(attributes)));
 	spin_unlock(&efivars->lock);
 
 	if (status != EFI_SUCCESS) {
@@ -818,9 +818,9 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 		goto out_free;
 	}
 
-	memcpy(data, &attributes, 4);
+	memcpy(data, &attributes, sizeof(attributes));
 	size = simple_read_from_buffer(userbuf, count, ppos,
-					data, datasize + 4);
+				       data, datasize + sizeof(attributes));
 out_free:
 	kfree(data);
 
-- 
1.7.12.1


From 2835e3a8a7774d72c3e82b6f5350b4c6750c07db Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Mon, 22 Oct 2012 15:51:45 +0100
Subject: [PATCH 14/17] efivarfs: Add unique magic number

Using pstore's superblock magic number is no doubt going to cause
problems in the future. Give efivarfs its own magic number.

Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 2 +-
 include/linux/magic.h      | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 2c04434..3b0cf9a 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -991,7 +991,7 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_maxbytes          = MAX_LFS_FILESIZE;
 	sb->s_blocksize         = PAGE_CACHE_SIZE;
 	sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
-	sb->s_magic             = PSTOREFS_MAGIC;
+	sb->s_magic             = EFIVARFS_MAGIC;
 	sb->s_op                = &efivarfs_ops;
 	sb->s_time_gran         = 1;
 
diff --git a/include/linux/magic.h b/include/linux/magic.h
index e15192c..12f68c7 100644
--- a/include/linux/magic.h
+++ b/include/linux/magic.h
@@ -27,6 +27,7 @@
 #define ISOFS_SUPER_MAGIC	0x9660
 #define JFFS2_SUPER_MAGIC	0x72b6
 #define PSTOREFS_MAGIC		0x6165676C
+#define EFIVARFS_MAGIC		0xde5e81e4
 
 #define MINIX_SUPER_MAGIC	0x137F		/* minix v1 fs, 14 char names */
 #define MINIX_SUPER_MAGIC2	0x138F		/* minix v1 fs, 30 char names */
-- 
1.7.12.1


From 6cd03d922cfcdf802a0b7cb28a2d12b85064e1cf Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Tue, 23 Oct 2012 12:35:43 +0100
Subject: [PATCH 15/17] efivarfs: Make 'datasize' unsigned long

There's no reason to declare 'datasize' as an int, since the majority
of the functions it's passed to expect an unsigned long anyway. Plus,
this way we avoid any sign problems during arithmetic.

Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 3b0cf9a..6a858d1 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -692,7 +692,7 @@ static ssize_t efivarfs_file_write(struct file *file,
 	void *data;
 	u32 attributes;
 	struct inode *inode = file->f_mapping->host;
-	int datasize = count - sizeof(attributes);
+	unsigned long datasize = count - sizeof(attributes);
 	unsigned long newdatasize;
 
 	if (count < sizeof(attributes))
-- 
1.7.12.1


From b96ed46670ff62693e169066da6c44014b487da6 Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Tue, 23 Oct 2012 12:41:03 +0100
Subject: [PATCH 16/17] efivarfs: Return a consistent error when
 efivarfs_get_inode() fails

Instead of returning -ENOSPC if efivarfs_get_inode() fails we should
be returning -ENOMEM, since running out of memory is the only reason
it can fail.  Furthermore, that's the error value used everywhere else
in this file. It's also less likely to confuse users that hit this
error case.

Acked-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 6a858d1..58cec62 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -911,7 +911,7 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
 
 	inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
 	if (!inode)
-		return -ENOSPC;
+		return -ENOMEM;
 
 	var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
 	if (!var) {
-- 
1.7.12.1


From d537167e87d99d6fffa04f7f36de80a9bc7ffd4f Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Fri, 26 Oct 2012 12:18:53 +0100
Subject: [PATCH 17/17] efivarfs: Fix return value of efivarfs_file_write()

We're stuffing a variable of type size_t (unsigned) into a ssize_t
(signed) which, even though both types should be the same number of
bits, it's just asking for sign issues to be introduced.

Cc: Jeremy Kerr <jeremy.kerr@canonical.com>
Reported-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efivars.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 58cec62..9ac9340 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -694,6 +694,7 @@ static ssize_t efivarfs_file_write(struct file *file,
 	struct inode *inode = file->f_mapping->host;
 	unsigned long datasize = count - sizeof(attributes);
 	unsigned long newdatasize;
+	ssize_t bytes = 0;
 
 	if (count < sizeof(attributes))
 		return -EINVAL;
@@ -706,22 +707,22 @@ static ssize_t efivarfs_file_write(struct file *file,
 	efivars = var->efivars;
 
 	if (copy_from_user(&attributes, userbuf, sizeof(attributes))) {
-		count = -EFAULT;
+		bytes = -EFAULT;
 		goto out;
 	}
 
 	if (attributes & ~(EFI_VARIABLE_MASK)) {
-		count = -EINVAL;
+		bytes = -EINVAL;
 		goto out;
 	}
 
 	if (copy_from_user(data, userbuf + sizeof(attributes), datasize)) {
-		count = -EFAULT;
+		bytes = -EFAULT;
 		goto out;
 	}
 
 	if (validate_var(&var->var, data, datasize) == false) {
-		count = -EINVAL;
+		bytes = -EINVAL;
 		goto out;
 	}
 
@@ -744,6 +745,8 @@ static ssize_t efivarfs_file_write(struct file *file,
 		return efi_status_to_err(status);
 	}
 
+	bytes = count;
+
 	/*
 	 * 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
@@ -778,7 +781,7 @@ static ssize_t efivarfs_file_write(struct file *file,
 out:
 	kfree(data);
 
-	return count;
+	return bytes;
 }
 
 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
-- 
1.7.12.1