From: Kees Cook <keescook@chromium.org>
To: Alexander Popov <alex.popov@linux.com>
Cc: Jann Horn <jannh@google.com>, Will Deacon <will@kernel.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Krzysztof Kozlowski <krzk@kernel.org>,
Patrick Bellasi <patrick.bellasi@arm.com>,
David Howells <dhowells@redhat.com>,
Eric Biederman <ebiederm@xmission.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Laura Abbott <labbott@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
kernel-hardening@lists.openwall.com,
linux-kernel@vger.kernel.org, notify@kernel.org
Subject: Re: [PATCH RFC 2/2] lkdtm: Add heap spraying test
Date: Sat, 15 Aug 2020 09:59:56 -0700 [thread overview]
Message-ID: <202008150952.E81C4A52F@keescook> (raw)
In-Reply-To: <20200813151922.1093791-3-alex.popov@linux.com>
On Thu, Aug 13, 2020 at 06:19:22PM +0300, Alexander Popov wrote:
> Add a simple test for CONFIG_SLAB_QUARANTINE.
>
> It performs heap spraying that aims to reallocate the recently freed heap
> object. This technique is used for exploiting use-after-free
> vulnerabilities in the kernel code.
>
> This test shows that CONFIG_SLAB_QUARANTINE breaks heap spraying
> exploitation technique.
Yay tests!
>
> Signed-off-by: Alexander Popov <alex.popov@linux.com>
> ---
> drivers/misc/lkdtm/core.c | 1 +
> drivers/misc/lkdtm/heap.c | 40 ++++++++++++++++++++++++++++++++++++++
> drivers/misc/lkdtm/lkdtm.h | 1 +
> 3 files changed, 42 insertions(+)
>
> diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
> index a5e344df9166..78b7669c35eb 100644
> --- a/drivers/misc/lkdtm/core.c
> +++ b/drivers/misc/lkdtm/core.c
> @@ -126,6 +126,7 @@ static const struct crashtype crashtypes[] = {
> CRASHTYPE(SLAB_FREE_DOUBLE),
> CRASHTYPE(SLAB_FREE_CROSS),
> CRASHTYPE(SLAB_FREE_PAGE),
> + CRASHTYPE(HEAP_SPRAY),
> CRASHTYPE(SOFTLOCKUP),
> CRASHTYPE(HARDLOCKUP),
> CRASHTYPE(SPINLOCKUP),
> diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c
> index 1323bc16f113..a72a241e314a 100644
> --- a/drivers/misc/lkdtm/heap.c
> +++ b/drivers/misc/lkdtm/heap.c
> @@ -205,6 +205,46 @@ static void ctor_a(void *region)
> static void ctor_b(void *region)
> { }
>
> +#define HEAP_SPRAY_SIZE 128
> +
> +void lkdtm_HEAP_SPRAY(void)
> +{
> + int *addr;
> + int *spray_addrs[HEAP_SPRAY_SIZE] = { 0 };
(the 0 isn't needed -- and it was left there, it should be NULL)
> + unsigned long i = 0;
> +
> + addr = kmem_cache_alloc(a_cache, GFP_KERNEL);
I would prefer this test add its own cache (e.g. spray_cache), to avoid
misbehaviors between tests. (e.g. the a and b caches already run the
risk of getting corrupted weirdly.)
> + if (!addr) {
> + pr_info("Unable to allocate memory in lkdtm-heap-a cache\n");
> + return;
> + }
> +
> + *addr = 0x31337;
> + kmem_cache_free(a_cache, addr);
> +
> + pr_info("Performing heap spraying...\n");
> + for (i = 0; i < HEAP_SPRAY_SIZE; i++) {
> + spray_addrs[i] = kmem_cache_alloc(a_cache, GFP_KERNEL);
> + *spray_addrs[i] = 0x31337;
> + pr_info("attempt %lu: spray alloc addr %p vs freed addr %p\n",
> + i, spray_addrs[i], addr);
That's 128 lines spewed into dmesg... I would leave this out.
> + if (spray_addrs[i] == addr) {
> + pr_info("freed addr is reallocated!\n");
> + break;
> + }
> + }
> +
> + if (i < HEAP_SPRAY_SIZE)
> + pr_info("FAIL! Heap spraying succeed :(\n");
I'd move this into the "if (spray_addrs[i] == addr)" test instead of the
pr_info() that is there.
> + else
> + pr_info("OK! Heap spraying hasn't succeed :)\n");
And then make this an "if (i == HEAP_SPRAY_SIZE)" test
> +
> + for (i = 0; i < HEAP_SPRAY_SIZE; i++) {
> + if (spray_addrs[i])
> + kmem_cache_free(a_cache, spray_addrs[i]);
> + }
> +}
> +
> void __init lkdtm_heap_init(void)
> {
> double_free_cache = kmem_cache_create("lkdtm-heap-double_free",
> diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
> index 8878538b2c13..dfafb4ae6f3a 100644
> --- a/drivers/misc/lkdtm/lkdtm.h
> +++ b/drivers/misc/lkdtm/lkdtm.h
> @@ -45,6 +45,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void);
> void lkdtm_SLAB_FREE_DOUBLE(void);
> void lkdtm_SLAB_FREE_CROSS(void);
> void lkdtm_SLAB_FREE_PAGE(void);
> +void lkdtm_HEAP_SPRAY(void);
>
> /* lkdtm_perms.c */
> void __init lkdtm_perms_init(void);
> --
> 2.26.2
>
I assume enabling the quarantine defense also ends up being seen in the
SLAB_FREE_DOUBLE LKDTM test too, yes?
--
Kees Cook
next prev parent reply other threads:[~2020-08-15 17:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 15:19 [PATCH RFC 0/2] Break heap spraying needed for exploiting use-after-free Alexander Popov
2020-08-13 15:19 ` [PATCH RFC 1/2] mm: Extract SLAB_QUARANTINE from KASAN Alexander Popov
2020-08-15 16:52 ` Kees Cook
2020-08-17 11:53 ` Andrey Konovalov
2020-08-17 17:32 ` Alexander Popov
2020-08-18 15:45 ` Andrey Konovalov
2020-08-18 20:50 ` Alexander Popov
2020-08-15 18:54 ` Matthew Wilcox
2020-08-16 19:59 ` Pavel Machek
2020-08-17 21:03 ` Alexander Popov
2020-08-17 20:34 ` Alexander Popov
2020-08-13 15:19 ` [PATCH RFC 2/2] lkdtm: Add heap spraying test Alexander Popov
2020-08-15 16:59 ` Kees Cook [this message]
2020-08-17 17:54 ` Alexander Popov
2020-08-17 18:24 ` Eric W. Biederman
2020-08-17 19:24 ` Kees Cook
2020-08-14 21:01 ` [PATCH RFC 0/2] Break heap spraying needed for exploiting use-after-free Alexander Popov
2020-08-15 16:39 ` Kees Cook
2020-08-18 9:08 ` Alexander Popov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=202008150952.E81C4A52F@keescook \
--to=keescook@chromium.org \
--cc=akpm@linux-foundation.org \
--cc=alex.popov@linux.com \
--cc=arnd@arndb.de \
--cc=aryabinin@virtuozzo.com \
--cc=cl@linux.com \
--cc=dhowells@redhat.com \
--cc=dvyukov@google.com \
--cc=ebiederm@xmission.com \
--cc=glider@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=hannes@cmpxchg.org \
--cc=iamjoonsoo.kim@lge.com \
--cc=jannh@google.com \
--cc=kasan-dev@googlegroups.com \
--cc=kernel-hardening@lists.openwall.com \
--cc=krzk@kernel.org \
--cc=labbott@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=masahiroy@kernel.org \
--cc=mhiramat@kernel.org \
--cc=notify@kernel.org \
--cc=patrick.bellasi@arm.com \
--cc=penberg@kernel.org \
--cc=peterz@infradead.org \
--cc=rientjes@google.com \
--cc=rostedt@goodmis.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).