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-rw-r--r--fs/efivarfs/super.c571
1 files changed, 571 insertions, 0 deletions
diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
new file mode 100644
index 000000000..8d33f11db
--- /dev/null
+++ b/fs/efivarfs/super.c
@@ -0,0 +1,571 @@
+// 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)) {
+ static DEFINE_RATELIMIT_STATE(_rs, 2 * HZ, 5);
+ static u64 storage, remaining;
+ static DEFINE_SPINLOCK(lock);
+
+ if (!__ratelimit(&_rs)) {
+ ratelimit_set_flags(&_rs, RATELIMIT_MSG_ON_RELEASE);
+
+ spin_lock(&lock);
+ storage_space = storage;
+ remaining_space = remaining;
+ spin_unlock(&lock);
+ } else {
+ status = efivar_query_variable_info(attr, &storage_space,
+ &remaining_space,
+ &max_variable_size);
+ if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED)
+ pr_warn("query_variable_info() failed: 0x%lx\n",
+ status);
+
+ spin_lock(&lock);
+ storage = storage_space;
+ remaining = remaining_space;
+ spin_unlock(&lock);
+ }
+ }
+
+ /*
+ * 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);
generated by cgit v1.3.1 (git 2.54.0) at 2026-10-12 12:39:19 +0000