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Message-ID: <b2c4f714-7276-7f1d-436c-7a31c6019345@gmail.com>
Date: Tue, 6 Mar 2018 09:13:06 -0800
From: J Freyensee <why2jjj.linux@...il.com>
To: Igor Stoppa <igor.stoppa@...wei.com>, david@...morbit.com,
willy@...radead.org, keescook@...omium.org, mhocko@...nel.org
Cc: labbott@...hat.com, linux-security-module@...r.kernel.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH 5/7] Pmalloc selftest
Looks good, and a bit more thorough test than last iteration.
Reviewed-by: Jay Freyensee <why2jjj.linux@...il.com>
On 2/28/18 12:06 PM, Igor Stoppa wrote:
> Add basic self-test functionality for pmalloc.
>
> The testing is introduced as early as possible, right after the main
> dependency, genalloc, has passed successfully, so that it can help
> diagnosing failures in pmalloc users.
>
> Signed-off-by: Igor Stoppa <igor.stoppa@...wei.com>
> ---
> include/linux/test_pmalloc.h | 24 +++++++++++
> init/main.c | 2 +
> mm/Kconfig | 10 +++++
> mm/Makefile | 1 +
> mm/test_pmalloc.c | 100 +++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 137 insertions(+)
> create mode 100644 include/linux/test_pmalloc.h
> create mode 100644 mm/test_pmalloc.c
>
> diff --git a/include/linux/test_pmalloc.h b/include/linux/test_pmalloc.h
> new file mode 100644
> index 000000000000..c7e2e451c17c
> --- /dev/null
> +++ b/include/linux/test_pmalloc.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * test_pmalloc.h
> + *
> + * (C) Copyright 2018 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <igor.stoppa@...wei.com>
> + */
> +
> +
> +#ifndef __LINUX_TEST_PMALLOC_H
> +#define __LINUX_TEST_PMALLOC_H
> +
> +
> +#ifdef CONFIG_TEST_PROTECTABLE_MEMORY
> +
> +void test_pmalloc(void);
> +
> +#else
> +
> +static inline void test_pmalloc(void){};
> +
> +#endif
> +
> +#endif
> diff --git a/init/main.c b/init/main.c
> index 2bf1312fd2fe..ea44c940070a 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -91,6 +91,7 @@
> #include <linux/rodata_test.h>
> #include <linux/jump_label.h>
> #include <linux/test_genalloc.h>
> +#include <linux/test_pmalloc.h>
>
> #include <asm/io.h>
> #include <asm/bugs.h>
> @@ -663,6 +664,7 @@ asmlinkage __visible void __init start_kernel(void)
> mem_encrypt_init();
>
> test_genalloc();
> + test_pmalloc();
> #ifdef CONFIG_BLK_DEV_INITRD
> if (initrd_start && !initrd_below_start_ok &&
> page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 016d29b9400b..47b0843b02d2 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -767,3 +767,13 @@ config PROTECTABLE_MEMORY
> depends on ARCH_HAS_SET_MEMORY
> select GENERIC_ALLOCATOR
> default y
> +
> +config TEST_PROTECTABLE_MEMORY
> + bool "Run self test for pmalloc memory allocator"
> + depends on MMU
> + depends on ARCH_HAS_SET_MEMORY
> + select PROTECTABLE_MEMORY
> + default n
> + help
> + Tries to verify that pmalloc works correctly and that the memory
> + is effectively protected.
> diff --git a/mm/Makefile b/mm/Makefile
> index 959fdbdac118..1de4be5fd0bc 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -66,6 +66,7 @@ obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
> obj-$(CONFIG_SLOB) += slob.o
> obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
> obj-$(CONFIG_PROTECTABLE_MEMORY) += pmalloc.o
> +obj-$(CONFIG_TEST_PROTECTABLE_MEMORY) += test_pmalloc.o
> obj-$(CONFIG_KSM) += ksm.o
> obj-$(CONFIG_PAGE_POISONING) += page_poison.o
> obj-$(CONFIG_SLAB) += slab.o
> diff --git a/mm/test_pmalloc.c b/mm/test_pmalloc.c
> new file mode 100644
> index 000000000000..df7ecc91c6a4
> --- /dev/null
> +++ b/mm/test_pmalloc.c
> @@ -0,0 +1,100 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * test_pmalloc.c
> + *
> + * (C) Copyright 2018 Huawei Technologies Co. Ltd.
> + * Author: Igor Stoppa <igor.stoppa@...wei.com>
> + */
> +
> +#include <linux/pmalloc.h>
> +#include <linux/mm.h>
> +#include <linux/test_pmalloc.h>
> +#include <linux/bug.h>
> +
> +#define SIZE_1 (PAGE_SIZE * 3)
> +#define SIZE_2 1000
> +
> +static inline bool validate_alloc(bool expected, void *addr,
> + unsigned long size)
> +{
> + bool test;
> +
> + test = is_pmalloc_object(addr, size) > 0;
> + pr_notice("must be %s: %s",
> + expected ? "ok" : "no", test ? "ok" : "no");
> + return test == expected;
> +}
> +
> +#define is_alloc_ok(variable, size) \
> + validate_alloc(true, variable, size)
> +
> +#define is_alloc_no(variable, size) \
> + validate_alloc(false, variable, size)
> +
> +void test_pmalloc(void)
> +{
> + struct gen_pool *pool_unprot;
> + struct gen_pool *pool_prot;
> + void *var_prot, *var_unprot, *var_vmall;
> +
> + pr_notice("pmalloc-selftest");
> + pool_unprot = pmalloc_create_pool("unprotected", 0);
> + if (unlikely(!pool_unprot))
> + goto error;
> + pool_prot = pmalloc_create_pool("protected", 0);
> + if (unlikely(!(pool_prot)))
> + goto error_release;
> +
> + pr_notice("Testing allocation capability");
> + var_unprot = pmalloc(pool_unprot, SIZE_1 - 1, GFP_KERNEL);
> + var_prot = pmalloc(pool_prot, SIZE_1, GFP_KERNEL);
> + *(int *)var_prot = 0;
> + var_vmall = vmalloc(SIZE_2);
> +
> +
> + pr_notice("Test correctness of is_pmalloc_object()");
> + WARN_ON(unlikely(!is_alloc_ok(var_unprot, 10)));
> + WARN_ON(unlikely(!is_alloc_ok(var_unprot, SIZE_1)));
> + WARN_ON(unlikely(!is_alloc_ok(var_unprot, PAGE_SIZE)));
> + WARN_ON(unlikely(!is_alloc_no(var_unprot, SIZE_1 + 1)));
> + WARN_ON(unlikely(!is_alloc_no(var_vmall, 10)));
> +
> +
> + pfree(pool_unprot, var_unprot);
> + vfree(var_vmall);
> +
> + pmalloc_protect_pool(pool_prot);
> +
> + /*
> + * This will intentionally trigger a WARN, because the pool being
> + * allocated from is already protected.
> + */
> + pr_notice("Test allocation from a protected pool."
> + "Expect WARN in pmalloc");
> + if (unlikely(pmalloc(pool_prot, 10, GFP_KERNEL)))
> + WARN(true, "no memory from a protected pool");
> +
> + /*
> + * This will intentionally trigger a WARN because the pool being
> + * destroyed is not protected, which is unusual and should happen
> + * on error paths only, where probably other warnings are already
> + * displayed.
> + */
> + pr_notice("pmalloc-selftest:"
> + " Expect WARN in pmalloc_pool_set_protection below.");
> + pmalloc_destroy_pool(pool_unprot);
> + pr_notice("pmalloc-selftest:"
> + "Critical point for expected WARN passed.");
> +
> + /* This must not cause WARNings */
> + pr_notice("pmalloc-selftest:"
> + "Expect no WARN below.");
> + pmalloc_destroy_pool(pool_prot);
> + pr_notice("pmalloc-selftest:"
> + "Critical point for unexpected WARN passed.");
> + return;
> +error_release:
> + pmalloc_destroy_pool(pool_unprot);
> +error:
> + WARN(true, "Unable to allocate memory for pmalloc selftest.");
> +}
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