linux/fs/efivarfs/super.c

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// 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/module.h>
#include <linux/pagemap.h>
#include <linux/ucs2_string.h>
#include <linux/slab.h>
#include <linux/magic.h>
#include "internal.h"
LIST_HEAD(efivarfs_list);
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,
};
/*
* 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;
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;
if (!efivarfs_valid_name(s, len))
return -EINVAL;
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,
.d_delete = always_delete_dentry,
};
static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
{
struct dentry *d;
struct qstr q;
int err;
q.name = name;
q.len = strlen(name);
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);
}
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;
struct efivar_entry *entry;
struct inode *inode = NULL;
struct dentry *dentry, *root = sb->s_root;
unsigned long size = 0;
char *name;
int len;
int err = -ENOMEM;
bool is_removable = false;
entry = kzalloc(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_utf8size(entry->var.VariableName);
/* name, plus '-', plus GUID, plus NUL*/
name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
if (!name)
goto fail;
ucs2_as_utf8(name, entry->var.VariableName, len);
if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
is_removable = true;
name[len] = '-';
efi_guid_to_str(&entry->var.VendorGuid, 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, '/', '!');
inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
is_removable);
if (!inode)
goto fail_name;
dentry = efivarfs_alloc_dentry(root, name);
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
goto fail_inode;
}
efivar_entry_size(entry, &size);
err = efivar_entry_add(entry, &efivarfs_list);
if (err)
goto fail_inode;
/* 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(entry->var.Attributes));
inode_unlock(inode);
d_add(dentry, inode);
return 0;
fail_inode:
iput(inode);
fail_name:
kfree(name);
fail:
kfree(entry);
return err;
}
static int efivarfs_destroy(struct efivar_entry *entry, void *data)
{
int err = efivar_entry_remove(entry);
if (err)
return err;
kfree(entry);
return 0;
}
static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct inode *inode = NULL;
struct dentry *root;
int err;
sb->s_maxbytes = MAX_LFS_FILESIZE;
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 12:29:47 +00:00
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;
sb->s_time_gran = 1;
efi/efivars: Expose RT service availability via efivars abstraction Commit bf67fad19e493b ("efi: Use more granular check for availability for variable services") introduced a check into the efivarfs, efi-pstore and other drivers that aborts loading of the module if not all three variable runtime services (GetVariable, SetVariable and GetNextVariable) are supported. However, this results in efivarfs being unavailable entirely if only SetVariable support is missing, which is only needed if you want to make any modifications. Also, efi-pstore and the sysfs EFI variable interface could be backed by another implementation of the 'efivars' abstraction, in which case it is completely irrelevant which services are supported by the EFI firmware. So make the generic 'efivars' abstraction dependent on the availibility of the GetVariable and GetNextVariable EFI runtime services, and add a helper 'efivar_supports_writes()' to find out whether the currently active efivars abstraction supports writes (and wire it up to the availability of SetVariable for the generic one). Then, use the efivar_supports_writes() helper to decide whether to permit efivarfs to be mounted read-write, and whether to enable efi-pstore or the sysfs EFI variable interface altogether. Fixes: bf67fad19e493b ("efi: Use more granular check for availability for variable services") Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de> Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Tested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-07-08 10:01:57 +00:00
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;
INIT_LIST_HEAD(&efivarfs_list);
err = efivar_init(efivarfs_callback, (void *)sb, true, &efivarfs_list);
if (err)
__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
return err;
}
static int efivarfs_get_tree(struct fs_context *fc)
{
return get_tree_single(fc, efivarfs_fill_super);
}
static const struct fs_context_operations efivarfs_context_ops = {
.get_tree = efivarfs_get_tree,
};
static int efivarfs_init_fs_context(struct fs_context *fc)
{
fc->ops = &efivarfs_context_ops;
return 0;
}
static void efivarfs_kill_sb(struct super_block *sb)
{
kill_litter_super(sb);
/* Remove all entries and destroy */
__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
}
static struct file_system_type efivarfs_type = {
.owner = THIS_MODULE,
.name = "efivarfs",
.init_fs_context = efivarfs_init_fs_context,
.kill_sb = efivarfs_kill_sb,
};
static __init int efivarfs_init(void)
{
if (!efivars_kobject())
return -ENODEV;
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);