1 files changed, 384 insertions, 97 deletions

diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index a8766b880c07..9da992925920 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -1,39 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2012 Red Hat, Inc.
  * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #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(sizeof(*entry), GFP_KERNEL);
+
+	if (!entry)
+		return NULL;
 
-LIST_HEAD(efivarfs_list);
+	inode_init_once(&entry->vfs_inode);
+	entry->removed = false;
 
-static void efivarfs_evict_inode(struct inode *inode)
+	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)
 {
-	clear_inode(inode);
+	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 = simple_statfs,
-	.drop_inode = generic_delete_inode,
-	.evict_inode = efivarfs_evict_inode,
-	.show_options = generic_show_options,
+	.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,
 };
 
-static struct super_block *efivarfs_sb;
-
 /*
  * Compare two efivarfs file names.
  *
@@ -45,13 +146,16 @@ static struct super_block *efivarfs_sb;
  * 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 *parent,
-			      const struct dentry *dentry,
+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;
 
@@ -65,13 +169,10 @@ static int efivarfs_d_compare(const struct dentry *parent,
 
 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
 {
-	unsigned long hash = init_name_hash();
+	unsigned long hash = init_name_hash(dentry);
 	const unsigned char *s = qstr->name;
 	unsigned int len = qstr->len;
 
-	if (!efivarfs_valid_name(s, len))
-		return -EINVAL;
-
 	while (len-- > EFI_VARIABLE_GUID_LEN)
 		hash = partial_name_hash(*s++, hash);
 
@@ -83,19 +184,9 @@ static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
 	return 0;
 }
 
-/*
- * Retaining negative dentries for an in-memory filesystem just wastes
- * memory and lookup time: arrange for them to be deleted immediately.
- */
-static int efivarfs_delete_dentry(const struct dentry *dentry)
-{
-	return 1;
-}
-
-static struct dentry_operations efivarfs_d_ops = {
+static const struct dentry_operations efivarfs_d_ops = {
 	.d_compare = efivarfs_d_compare,
 	.d_hash = efivarfs_d_hash,
-	.d_delete = efivarfs_delete_dentry,
 };
 
 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
@@ -107,7 +198,7 @@ static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
 	q.name = name;
 	q.len = strlen(name);
 
-	err = efivarfs_d_hash(NULL, &q);
+	err = efivarfs_d_hash(parent, &q);
 	if (err)
 		return ERR_PTR(err);
 
@@ -118,62 +209,77 @@ static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
 	return ERR_PTR(-ENOMEM);
 }
 
-static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
-			     unsigned long name_size, void *data)
+bool efivarfs_variable_is_present(efi_char16_t *variable_name,
+				  efi_guid_t *vendor, void *data)
 {
-	struct super_block *sb = (struct super_block *)data;
-	struct efivar_entry *entry;
-	struct inode *inode = NULL;
-	struct dentry *dentry, *root = sb->s_root;
-	unsigned long size = 0;
-	char *name;
-	int len, i;
-	int err = -ENOMEM;
+	char *name = efivar_get_utf8name(variable_name, vendor);
+	struct super_block *sb = data;
+	struct dentry *dentry;
 
-	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
-	if (!entry)
-		return err;
-
-	memcpy(entry->var.VariableName, name16, name_size);
-	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
-
-	len = ucs2_strlen(entry->var.VariableName);
-
-	/* name, plus '-', plus GUID, plus NUL*/
-	name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
 	if (!name)
-		goto fail;
+		/*
+		 * 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);
 
-	for (i = 0; i < len; i++)
-		name[i] = entry->var.VariableName[i] & 0xFF;
+	return dentry != NULL;
+}
 
-	name[len] = '-';
+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;
 
-	efi_guid_unparse(&entry->var.VendorGuid, name + len + 1);
+	/* length of the variable name itself: remove GUID and separator */
+	len = strlen(name) - EFI_VARIABLE_GUID_LEN - 1;
 
-	name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
+	if (efivar_variable_is_removable(vendor, name, len))
+		is_removable = true;
 
-	inode = efivarfs_get_inode(sb, root->d_inode, S_IFREG | 0644, 0);
+	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);
 
-	efivar_entry_size(entry, &size);
-	efivar_entry_add(entry, &efivarfs_list);
-
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	inode->i_private = entry;
-	i_size_write(inode, size + sizeof(entry->var.Attributes));
-	mutex_unlock(&inode->i_mutex);
-	d_add(dentry, inode);
+	i_size_write(inode, size + sizeof(__u32)); /* attributes + data */
+	inode_unlock(inode);
+	d_make_persistent(dentry, inode);
+	dput(dentry);
 
 	return 0;
 
@@ -181,35 +287,81 @@ fail_inode:
 	iput(inode);
 fail_name:
 	kfree(name);
-fail:
-	kfree(entry);
+
 	return err;
 }
 
-static int efivarfs_destroy(struct efivar_entry *entry, void *data)
+static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
+			     unsigned long name_size, void *data)
 {
-	efivar_entry_remove(entry);
-	kfree(entry);
+	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, void *data, int silent)
+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;
 
-	efivarfs_sb = sb;
-
 	sb->s_maxbytes          = MAX_LFS_FILESIZE;
-	sb->s_blocksize         = PAGE_CACHE_SIZE;
-	sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
+	sb->s_blocksize         = PAGE_SIZE;
+	sb->s_blocksize_bits    = PAGE_SHIFT;
 	sb->s_magic             = EFIVARFS_MAGIC;
 	sb->s_op                = &efivarfs_ops;
-	sb->s_d_op		= &efivarfs_d_ops;
+	set_default_d_op(sb, &efivarfs_d_ops);
+	sb->s_d_flags |= DCACHE_DONTCACHE;
 	sb->s_time_gran         = 1;
 
-	inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
+	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;
@@ -219,51 +371,186 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	if (!root)
 		return -ENOMEM;
 
-	INIT_LIST_HEAD(&efivarfs_list);
-
-	err = efivar_init(efivarfs_callback, (void *)sb, false,
-			  true, &efivarfs_list);
+	sfi->sb = sb;
+	sfi->nb.notifier_call = efivarfs_ops_notifier;
+	err = blocking_notifier_chain_register(&efivar_ops_nh, &sfi->nb);
 	if (err)
-		__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
+		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 dentry *efivarfs_mount(struct file_system_type *fs_type,
-				    int flags, const char *dev_name, void *data)
+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)
 {
-	return mount_single(fs_type, flags, data, efivarfs_fill_super);
+	struct efivarfs_fs_info *sfi;
+
+	if (!efivar_is_available())
+		return -EOPNOTSUPP;
+
+	sfi = kzalloc(sizeof(*sfi), GFP_KERNEL);
+	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)
 {
-	kill_litter_super(sb);
-	efivarfs_sb = NULL;
+	struct efivarfs_fs_info *sfi = sb->s_fs_info;
+
+	blocking_notifier_chain_unregister(&efivar_ops_nh, &sfi->nb);
+	kill_anon_super(sb);
 
-	/* Remove all entries and destroy */
-	__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
+	kfree(sfi);
 }
 
 static struct file_system_type efivarfs_type = {
+	.owner   = THIS_MODULE,
 	.name    = "efivarfs",
-	.mount   = efivarfs_mount,
+	.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)
 {
-	if (!efi_enabled(EFI_RUNTIME_SERVICES))
-		return 0;
-
-	if (!efivars_kobject())
-		return 0;
-
 	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);