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    SubjectRe: [PATCH 5/6] Pmalloc: self-test
    On Mon, Feb 12, 2018 at 8:53 AM, Igor Stoppa <igor.stoppa@huawei.com> wrote:
    > Add basic self-test functionality for pmalloc.
    >
    > Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com>
    > ---
    > mm/Kconfig | 9 ++++++++
    > mm/Makefile | 1 +
    > mm/pmalloc-selftest.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++
    > mm/pmalloc-selftest.h | 24 +++++++++++++++++++
    > mm/pmalloc.c | 2 ++
    > 5 files changed, 100 insertions(+)
    > create mode 100644 mm/pmalloc-selftest.c
    > create mode 100644 mm/pmalloc-selftest.h
    >
    > diff --git a/mm/Kconfig b/mm/Kconfig
    > index be578fbdce6d..098aefef78b1 100644
    > --- a/mm/Kconfig
    > +++ b/mm/Kconfig
    > @@ -766,3 +766,12 @@ config PROTECTABLE_MEMORY
    > depends on ARCH_HAS_SET_MEMORY
    > select GENERIC_ALLOCATOR
    > default y
    > +
    > +config PROTECTABLE_MEMORY_SELFTEST
    > + bool "Run self test for pmalloc memory allocator"
    > + 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..f7bbbfde6967 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_PROTECTABLE_MEMORY_SELFTEST) += pmalloc-selftest.o

    Nit: self-test modules are traditionally named "test_$thing.o"
    (outside of the tools/ directory).

    > obj-$(CONFIG_KSM) += ksm.o
    > obj-$(CONFIG_PAGE_POISONING) += page_poison.o
    > obj-$(CONFIG_SLAB) += slab.o
    > diff --git a/mm/pmalloc-selftest.c b/mm/pmalloc-selftest.c
    > new file mode 100644
    > index 000000000000..97ba52d17f69
    > --- /dev/null
    > +++ b/mm/pmalloc-selftest.c
    > @@ -0,0 +1,64 @@
    > +// SPDX-License-Identifier: GPL-2.0
    > +/*
    > + * pmalloc-selftest.c
    > + *
    > + * (C) Copyright 2018 Huawei Technologies Co. Ltd.
    > + * Author: Igor Stoppa <igor.stoppa@huawei.com>
    > + */
    > +
    > +#include <linux/pmalloc.h>
    > +#include <linux/mm.h>
    > +
    > +#include "pmalloc-selftest.h"
    > +
    > +#define SIZE_1 (PAGE_SIZE * 3)
    > +#define SIZE_2 1000
    > +
    > +#define validate_alloc(expected, variable, size) \
    > + pr_notice("must be " expected ": %s", \
    > + is_pmalloc_object(variable, size) > 0 ? "ok" : "no")
    > +
    > +#define is_alloc_ok(variable, size) \
    > + validate_alloc("ok", variable, size)
    > +
    > +#define is_alloc_no(variable, size) \
    > + validate_alloc("no", variable, size)
    > +
    > +void pmalloc_selftest(void)
    > +{
    > + struct gen_pool *pool_unprot;
    > + struct gen_pool *pool_prot;
    > + void *var_prot, *var_unprot, *var_vmall;
    > +
    > + pr_notice("pmalloc self-test");
    > + pool_unprot = pmalloc_create_pool("unprotected", 0);
    > + pool_prot = pmalloc_create_pool("protected", 0);
    > + BUG_ON(!(pool_unprot && pool_prot));
    > +
    > + 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);
    > + is_alloc_ok(var_unprot, 10);
    > + is_alloc_ok(var_unprot, SIZE_1);
    > + is_alloc_ok(var_unprot, PAGE_SIZE);
    > + is_alloc_no(var_unprot, SIZE_1 + 1);
    > + 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
    > + * destroyed is not protected, which is unusual and should happen
    > + * on error paths only, where probably other warnings are already
    > + * displayed.
    > + */
    > + pmalloc_destroy_pool(pool_unprot);
    > +
    > + /* This must not cause WARNings */
    > + pmalloc_destroy_pool(pool_prot);
    > +}

    I wonder if lkdtm should grow a test too, to validate the RO-ness of
    the allocations at the right time in API usage?

    Otherwise, yay! Selftests!

    -Kees

    > diff --git a/mm/pmalloc-selftest.h b/mm/pmalloc-selftest.h
    > new file mode 100644
    > index 000000000000..58a5a0cbec14
    > --- /dev/null
    > +++ b/mm/pmalloc-selftest.h
    > @@ -0,0 +1,24 @@
    > +/* SPDX-License-Identifier: GPL-2.0 */
    > +/*
    > + * pmalloc-selftest.h
    > + *
    > + * (C) Copyright 2018 Huawei Technologies Co. Ltd.
    > + * Author: Igor Stoppa <igor.stoppa@huawei.com>
    > + */
    > +
    > +
    > +#ifndef __MM_PMALLOC_SELFTEST_H
    > +#define __MM_PMALLOC_SELFTEST_H
    > +
    > +
    > +#ifdef CONFIG_PROTECTABLE_MEMORY_SELFTEST
    > +
    > +void pmalloc_selftest(void);
    > +
    > +#else
    > +
    > +static inline void pmalloc_selftest(void){};
    > +
    > +#endif
    > +
    > +#endif
    > diff --git a/mm/pmalloc.c b/mm/pmalloc.c
    > index abddba90a9f6..eb445c574b19 100644
    > --- a/mm/pmalloc.c
    > +++ b/mm/pmalloc.c
    > @@ -22,6 +22,7 @@
    > #include <asm/page.h>
    >
    > #include <linux/pmalloc.h>
    > +#include "pmalloc-selftest.h"
    > /*
    > * pmalloc_data contains the data specific to a pmalloc pool,
    > * in a format compatible with the design of gen_alloc.
    > @@ -494,6 +495,7 @@ static int __init pmalloc_late_init(void)
    > }
    > }
    > mutex_unlock(&pmalloc_mutex);
    > + pmalloc_selftest();
    > return 0;
    > }
    > late_initcall(pmalloc_late_init);
    > --
    > 2.14.1
    >



    --
    Kees Cook
    Pixel Security

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