Revision 706a1ea65e6faaf853427a0e931f59d604dd45e3 authored by Linus Torvalds on 23 August 2018, 21:55:01 UTC, committed by Linus Torvalds on 23 August 2018, 21:55:01 UTC
Merge fixes for missing TLB shootdowns. This fixes a couple of cases that involved us possibly freeing page table structures before the required TLB shootdown had been done. There are a few cleanup patches to make the code easier to follow, and to avoid some of the more problematic cases entirely when not necessary. To make this easier for backports, it undoes the recent lazy TLB patches, because the cleanups and fixes are more important, and Rik is ok with re-doing them later when things have calmed down. The missing TLB flush was only delayed, and the wrong ordering only happened under memory pressure (and in theory under a couple of other fairly theoretical situations), so this may have been all very unlikely to have hit people in practice. But getting the TLB shootdown wrong is _so_ hard to debug and see that I consider this a crticial fix. Many thanks to Jann Horn for having debugged this. * tlb-fixes: x86/mm: Only use tlb_remove_table() for paravirt mm: mmu_notifier fix for tlb_end_vma mm/tlb, x86/mm: Support invalidating TLB caches for RCU_TABLE_FREE mm/tlb: Remove tlb_remove_table() non-concurrent condition mm: move tlb_table_flush to tlb_flush_mmu_free x86/mm/tlb: Revert the recent lazy TLB patches
blacklist.c
/* System hash blacklist.
*
* Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define pr_fmt(fmt) "blacklist: "fmt
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/key.h>
#include <linux/key-type.h>
#include <linux/sched.h>
#include <linux/ctype.h>
#include <linux/err.h>
#include <linux/seq_file.h>
#include <keys/system_keyring.h>
#include "blacklist.h"
static struct key *blacklist_keyring;
/*
* The description must be a type prefix, a colon and then an even number of
* hex digits. The hash is kept in the description.
*/
static int blacklist_vet_description(const char *desc)
{
int n = 0;
if (*desc == ':')
return -EINVAL;
for (; *desc; desc++)
if (*desc == ':')
goto found_colon;
return -EINVAL;
found_colon:
desc++;
for (; *desc; desc++) {
if (!isxdigit(*desc))
return -EINVAL;
n++;
}
if (n == 0 || n & 1)
return -EINVAL;
return 0;
}
/*
* The hash to be blacklisted is expected to be in the description. There will
* be no payload.
*/
static int blacklist_preparse(struct key_preparsed_payload *prep)
{
if (prep->datalen > 0)
return -EINVAL;
return 0;
}
static void blacklist_free_preparse(struct key_preparsed_payload *prep)
{
}
static void blacklist_describe(const struct key *key, struct seq_file *m)
{
seq_puts(m, key->description);
}
static struct key_type key_type_blacklist = {
.name = "blacklist",
.vet_description = blacklist_vet_description,
.preparse = blacklist_preparse,
.free_preparse = blacklist_free_preparse,
.instantiate = generic_key_instantiate,
.describe = blacklist_describe,
};
/**
* mark_hash_blacklisted - Add a hash to the system blacklist
* @hash - The hash as a hex string with a type prefix (eg. "tbs:23aa429783")
*/
int mark_hash_blacklisted(const char *hash)
{
key_ref_t key;
key = key_create_or_update(make_key_ref(blacklist_keyring, true),
"blacklist",
hash,
NULL,
0,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW),
KEY_ALLOC_NOT_IN_QUOTA |
KEY_ALLOC_BUILT_IN);
if (IS_ERR(key)) {
pr_err("Problem blacklisting hash (%ld)\n", PTR_ERR(key));
return PTR_ERR(key);
}
return 0;
}
/**
* is_hash_blacklisted - Determine if a hash is blacklisted
* @hash: The hash to be checked as a binary blob
* @hash_len: The length of the binary hash
* @type: Type of hash
*/
int is_hash_blacklisted(const u8 *hash, size_t hash_len, const char *type)
{
key_ref_t kref;
size_t type_len = strlen(type);
char *buffer, *p;
int ret = 0;
buffer = kmalloc(type_len + 1 + hash_len * 2 + 1, GFP_KERNEL);
if (!buffer)
return -ENOMEM;
p = memcpy(buffer, type, type_len);
p += type_len;
*p++ = ':';
bin2hex(p, hash, hash_len);
p += hash_len * 2;
*p = 0;
kref = keyring_search(make_key_ref(blacklist_keyring, true),
&key_type_blacklist, buffer);
if (!IS_ERR(kref)) {
key_ref_put(kref);
ret = -EKEYREJECTED;
}
kfree(buffer);
return ret;
}
EXPORT_SYMBOL_GPL(is_hash_blacklisted);
/*
* Initialise the blacklist
*/
static int __init blacklist_init(void)
{
const char *const *bl;
if (register_key_type(&key_type_blacklist) < 0)
panic("Can't allocate system blacklist key type\n");
blacklist_keyring =
keyring_alloc(".blacklist",
KUIDT_INIT(0), KGIDT_INIT(0),
current_cred(),
(KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ |
KEY_USR_SEARCH,
KEY_ALLOC_NOT_IN_QUOTA |
KEY_FLAG_KEEP,
NULL, NULL);
if (IS_ERR(blacklist_keyring))
panic("Can't allocate system blacklist keyring\n");
for (bl = blacklist_hashes; *bl; bl++)
if (mark_hash_blacklisted(*bl) < 0)
pr_err("- blacklisting failed\n");
return 0;
}
/*
* Must be initialised before we try and load the keys into the keyring.
*/
device_initcall(blacklist_init);
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