Revision ec3937107ab43f3e8b2bc9dad95710043c462ff7 authored by Baoquan He on 04 April 2019, 02:03:13 UTC, committed by Borislav Petkov on 18 April 2019, 08:42:58 UTC
kernel_randomize_memory() uses __PHYSICAL_MASK_SHIFT to calculate the maximum amount of system RAM supported. The size of the direct mapping section is obtained from the smaller one of the below two values: (actual system RAM size + padding size) vs (max system RAM size supported) This calculation is wrong since commit b83ce5ee9147 ("x86/mm/64: Make __PHYSICAL_MASK_SHIFT always 52"). In it, __PHYSICAL_MASK_SHIFT was changed to be 52, regardless of whether the kernel is using 4-level or 5-level page tables. Thus, it will always use 4 PB as the maximum amount of system RAM, even in 4-level paging mode where it should actually be 64 TB. Thus, the size of the direct mapping section will always be the sum of the actual system RAM size plus the padding size. Even when the amount of system RAM is 64 TB, the following layout will still be used. Obviously KALSR will be weakened significantly. |____|_______actual RAM_______|_padding_|______the rest_______| 0 64TB ~120TB Instead, it should be like this: |____|_______actual RAM_______|_________the rest______________| 0 64TB ~120TB The size of padding region is controlled by CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING, which is 10 TB by default. The above issue only exists when CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING is set to a non-zero value, which is the case when CONFIG_MEMORY_HOTPLUG is enabled. Otherwise, using __PHYSICAL_MASK_SHIFT doesn't affect KASLR. Fix it by replacing __PHYSICAL_MASK_SHIFT with MAX_PHYSMEM_BITS. [ bp: Massage commit message. ] Fixes: b83ce5ee9147 ("x86/mm/64: Make __PHYSICAL_MASK_SHIFT always 52") Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Thomas Garnier <thgarnie@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: frank.ramsay@hpe.com Cc: herbert@gondor.apana.org.au Cc: kirill@shutemov.name Cc: mike.travis@hpe.com Cc: thgarnie@google.com Cc: x86-ml <x86@kernel.org> Cc: yamada.masahiro@socionext.com Link: https://lkml.kernel.org/r/20190417083536.GE7065@MiWiFi-R3L-srv
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kpp.c
/*
* Key-agreement Protocol Primitives (KPP)
*
* Copyright (c) 2016, Intel Corporation
* Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <crypto/algapi.h>
#include <linux/cryptouser.h>
#include <linux/compiler.h>
#include <net/netlink.h>
#include <crypto/kpp.h>
#include <crypto/internal/kpp.h>
#include "internal.h"
#ifdef CONFIG_NET
static int crypto_kpp_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_kpp rkpp;
memset(&rkpp, 0, sizeof(rkpp));
strscpy(rkpp.type, "kpp", sizeof(rkpp.type));
return nla_put(skb, CRYPTOCFGA_REPORT_KPP, sizeof(rkpp), &rkpp);
}
#else
static int crypto_kpp_report(struct sk_buff *skb, struct crypto_alg *alg)
{
return -ENOSYS;
}
#endif
static void crypto_kpp_show(struct seq_file *m, struct crypto_alg *alg)
__maybe_unused;
static void crypto_kpp_show(struct seq_file *m, struct crypto_alg *alg)
{
seq_puts(m, "type : kpp\n");
}
static void crypto_kpp_exit_tfm(struct crypto_tfm *tfm)
{
struct crypto_kpp *kpp = __crypto_kpp_tfm(tfm);
struct kpp_alg *alg = crypto_kpp_alg(kpp);
alg->exit(kpp);
}
static int crypto_kpp_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_kpp *kpp = __crypto_kpp_tfm(tfm);
struct kpp_alg *alg = crypto_kpp_alg(kpp);
if (alg->exit)
kpp->base.exit = crypto_kpp_exit_tfm;
if (alg->init)
return alg->init(kpp);
return 0;
}
static const struct crypto_type crypto_kpp_type = {
.extsize = crypto_alg_extsize,
.init_tfm = crypto_kpp_init_tfm,
#ifdef CONFIG_PROC_FS
.show = crypto_kpp_show,
#endif
.report = crypto_kpp_report,
.maskclear = ~CRYPTO_ALG_TYPE_MASK,
.maskset = CRYPTO_ALG_TYPE_MASK,
.type = CRYPTO_ALG_TYPE_KPP,
.tfmsize = offsetof(struct crypto_kpp, base),
};
struct crypto_kpp *crypto_alloc_kpp(const char *alg_name, u32 type, u32 mask)
{
return crypto_alloc_tfm(alg_name, &crypto_kpp_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_kpp);
static void kpp_prepare_alg(struct kpp_alg *alg)
{
struct crypto_alg *base = &alg->base;
base->cra_type = &crypto_kpp_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_KPP;
}
int crypto_register_kpp(struct kpp_alg *alg)
{
struct crypto_alg *base = &alg->base;
kpp_prepare_alg(alg);
return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_kpp);
void crypto_unregister_kpp(struct kpp_alg *alg)
{
crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_kpp);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Key-agreement Protocol Primitives");
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