From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80DF5EB64DC for ; Fri, 14 Jul 2023 07:09:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F09326B00AE; Fri, 14 Jul 2023 03:09:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EB9476B00AF; Fri, 14 Jul 2023 03:09:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D82118E000B; Fri, 14 Jul 2023 03:09:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id C844C6B00AE for ; Fri, 14 Jul 2023 03:09:36 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 8761F14014C for ; Fri, 14 Jul 2023 07:09:36 +0000 (UTC) X-FDA: 81009341952.27.CE706DC Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) by imf14.hostedemail.com (Postfix) with ESMTP id 27F5A100012 for ; Fri, 14 Jul 2023 07:09:31 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=none; spf=none (imf14.hostedemail.com: domain of gongruiqi@huaweicloud.com has no SPF policy when checking 45.249.212.51) smtp.mailfrom=gongruiqi@huaweicloud.com; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1689318573; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ydC02UEiRZG9EKa3p2y86VR8uRsV9ziNd2ZXZWdAS4c=; b=8Ni8SMirW8DVOjJSdc4w+sONs99ksGCo/P5tCBfSNj8bc6TU0UmzjqD4c5F9mq/3YLibFd MeQoiRU1x8esL2ERht6VtM/jKjgkd/wVc1ckw4DimhmydxC313+ZTRKN0emIt8zQqaKAjb l0OteS5WQWctZFoPUsDV/15s/Lq7uy4= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1689318573; a=rsa-sha256; cv=none; b=aEuCbrd9MfZaw4mKe7QzhlsUY3iOZn3XXbMGxOsn05emS701qBsLKZP4etGiuSccORRmC+ aUhbmysLjkK6f+RhrNw60H/No70c2gZX73x37Rpg23UfEBWcU+S+u/03eau4inIxtAzmem mbYTsgtW/NYPBZA3cgRp6bns74ZJ8ck= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=none; spf=none (imf14.hostedemail.com: domain of gongruiqi@huaweicloud.com has no SPF policy when checking 45.249.212.51) smtp.mailfrom=gongruiqi@huaweicloud.com; dmarc=none Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4R2MzT6gCdz4f3tq3 for ; Fri, 14 Jul 2023 15:09:25 +0800 (CST) Received: from [10.67.110.48] (unknown [10.67.110.48]) by APP3 (Coremail) with SMTP id _Ch0CgBnTQuj9LBk4Y+8Mw--.45485S2; Fri, 14 Jul 2023 15:09:24 +0800 (CST) Message-ID: <11e0a7af-ed31-3ac9-29ca-335dea05a730@huaweicloud.com> Date: Fri, 14 Jul 2023 15:09:23 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v4] Randomized slab caches for kmalloc() Content-Language: en-US To: Vlastimil Babka , Andrew Morton , Joonsoo Kim , David Rientjes , Pekka Enberg , Christoph Lameter , Tejun Heo , Dennis Zhou , Alexander Potapenko , Marco Elver , Kees Cook , Jann Horn Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Dmitry Vyukov , Alexander Lobakin , Pedro Falcato , Paul Moore , James Morris , "Serge E . Hallyn" , Markus Elfring , Wang Weiyang , Xiu Jianfeng , linux-mm@kvack.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, gongruiqi1@huawei.com, Julian Pidancet References: <20230626031835.2279738-1-gongruiqi@huaweicloud.com> From: "GONG, Ruiqi" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CM-TRANSID:_Ch0CgBnTQuj9LBk4Y+8Mw--.45485S2 X-Coremail-Antispam: 1UD129KBjvJXoW3AF43GF1DWF4kWF1fGF13XFb_yoW3Wr13p3 yUZr9rJ3yqgFy7Crn5uayF93WfZw4rK3yYkw13Wr4kuF4UXw10gFWDXrWrur1DXFn8Ca4x JF1q9r92qasxW37anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvab4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7Mxk0xIA0c2IE e2xFo4CEbIxvr21l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxV Aqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a 6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6x kF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWrJr0_WFyUJwCI42IY6I8E87Iv 67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyT uYvjxUFYFCUUUUU X-CM-SenderInfo: pjrqw2pxltxq5kxd4v5lfo033gof0z/ X-CFilter-Loop: Reflected X-Stat-Signature: be5mnscegw5cff5jts1srkx8nqezhmgj X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 27F5A100012 X-Rspam-User: X-HE-Tag: 1689318571-40689 X-HE-Meta: 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 tW7+I4qV b6ifxH/YuIPa9g06ohrxxGsjtk/e/hKuPLfw5jd3ckv9KDQKIBfp3rg8YK8wn4D5L7Ow7XfRiUB+PyXK3HsBvTEOG1YUa8ReT5wVnlM774c0uRj50VxwgCCuunM9y8zG90fwTI0phTJVn0KW2z9I2bBjkBGkBbj+w03o7VjmUnZ/WthIk0b6oJDYtggjimP0KGu+QPyoAOQ8KzLEBRrztqUnPZ94PBZDNRKF6gTgifwNkmLoA01Dud4SMJu6X7R8jrd3xegqzLRe1VmU9sSokqlaikyshdCxtPSJekw22XzoVLoWtsH+Id4H68LHh8vvStbzWhWmF5zJZv5Ly1/XEJYdAQA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023/07/13 20:46, Vlastimil Babka wrote: > > On 6/26/23 05:18, GONG, Ruiqi wrote: >> When exploiting memory vulnerabilities, "heap spraying" is a common >> technique targeting those related to dynamic memory allocation (i.e. the >> "heap"), and it plays an important role in a successful exploitation. >> Basically, it is to overwrite the memory area of vulnerable object by >> triggering allocation in other subsystems or modules and therefore >> getting a reference to the targeted memory location. It's usable on >> various types of vulnerablity including use after free (UAF), heap out- >> of-bound write and etc. >> >> There are (at least) two reasons why the heap can be sprayed: 1) generic >> slab caches are shared among different subsystems and modules, and >> 2) dedicated slab caches could be merged with the generic ones. >> Currently these two factors cannot be prevented at a low cost: the first >> one is a widely used memory allocation mechanism, and shutting down slab >> merging completely via `slub_nomerge` would be overkill. > > Interesting :) Here's a recent patch to make slub_nomerge a default: > https://lore.kernel.org/all/20230629221910.359711-1-julian.pidancet@oracle.com/ > > In v1, Kees said he's been running with that for ages: > https://lore.kernel.org/all/202306281358.E6E6C2759@keescook/ > > So it's not universally accepted in the kernel hardening community? > Thanks for the information! I'm not sure if the slub merging is that much unwelcomed in the hardening community, since I don't see hardening folks complaining a lot about it. I personally don't hate it as it does bring benefits for the performance, at least theoretically (e.g. keeping cache hot, reducing internal fragments etc.). > [...] > > Here's the renumbering diff. It assumes SLUB_TINY would be excluded as > suggested, otherwise more adjustment would be needed for KMALLOC_RECLAIM. > > ----8<---- > diff --git a/include/linux/slab.h b/include/linux/slab.h > index 96fdfd96b708..2f6337361515 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -347,10 +347,10 @@ static inline unsigned int arch_slab_minalign(void) > (KMALLOC_MIN_SIZE) : 16) > > #ifdef CONFIG_RANDOM_KMALLOC_CACHES > -#define RANDOM_KMALLOC_CACHES_NR 16 // # of cache copies > +#define RANDOM_KMALLOC_CACHES_NR 15 // # of extra cache copies > #define RANDOM_KMALLOC_CACHES_BITS 4 // =log2(_NR), for hashing > #else > -#define RANDOM_KMALLOC_CACHES_NR 1 > +#define RANDOM_KMALLOC_CACHES_NR 0 > #endif > > /* > @@ -362,15 +362,15 @@ static inline unsigned int arch_slab_minalign(void) > * kmem caches can have both accounted and unaccounted objects. > */ > enum kmalloc_cache_type { > - KMALLOC_RANDOM_START = 0, > - KMALLOC_RANDOM_END = KMALLOC_RANDOM_START + RANDOM_KMALLOC_CACHES_NR - 1, > - KMALLOC_NORMAL = KMALLOC_RANDOM_END, > + KMALLOC_NORMAL = 0, > #ifndef CONFIG_ZONE_DMA > KMALLOC_DMA = KMALLOC_NORMAL, > #endif > #ifndef CONFIG_MEMCG_KMEM > KMALLOC_CGROUP = KMALLOC_NORMAL, > #endif > + KMALLOC_RANDOM_START = KMALLOC_NORMAL, > + KMALLOC_RANDOM_END = KMALLOC_RANDOM_START + RANDOM_KMALLOC_CACHES_NR, > #ifdef CONFIG_SLUB_TINY > KMALLOC_RECLAIM = KMALLOC_NORMAL, > #else > diff --git a/mm/slab_common.c b/mm/slab_common.c > index a1a111ca229c..0479037b2959 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -784,22 +784,21 @@ EXPORT_SYMBOL(kmalloc_size_roundup); > #ifdef CONFIG_RANDOM_KMALLOC_CACHES > #define __KMALLOC_RANDOM_CONCAT(a, b) a ## b > #define KMALLOC_RANDOM_NAME(N, sz) __KMALLOC_RANDOM_CONCAT(KMA_RAND_, N)(sz) > -#define KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 0] = "kmalloc-rnd-01-" #sz, > -#define KMA_RAND_2(sz) KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 1] = "kmalloc-rnd-02-" #sz, > -#define KMA_RAND_3(sz) KMA_RAND_2(sz) .name[KMALLOC_RANDOM_START + 2] = "kmalloc-rnd-03-" #sz, > -#define KMA_RAND_4(sz) KMA_RAND_3(sz) .name[KMALLOC_RANDOM_START + 3] = "kmalloc-rnd-04-" #sz, > -#define KMA_RAND_5(sz) KMA_RAND_4(sz) .name[KMALLOC_RANDOM_START + 4] = "kmalloc-rnd-05-" #sz, > -#define KMA_RAND_6(sz) KMA_RAND_5(sz) .name[KMALLOC_RANDOM_START + 5] = "kmalloc-rnd-06-" #sz, > -#define KMA_RAND_7(sz) KMA_RAND_6(sz) .name[KMALLOC_RANDOM_START + 6] = "kmalloc-rnd-07-" #sz, > -#define KMA_RAND_8(sz) KMA_RAND_7(sz) .name[KMALLOC_RANDOM_START + 7] = "kmalloc-rnd-08-" #sz, > -#define KMA_RAND_9(sz) KMA_RAND_8(sz) .name[KMALLOC_RANDOM_START + 8] = "kmalloc-rnd-09-" #sz, > -#define KMA_RAND_10(sz) KMA_RAND_9(sz) .name[KMALLOC_RANDOM_START + 9] = "kmalloc-rnd-10-" #sz, > -#define KMA_RAND_11(sz) KMA_RAND_10(sz) .name[KMALLOC_RANDOM_START + 10] = "kmalloc-rnd-11-" #sz, > -#define KMA_RAND_12(sz) KMA_RAND_11(sz) .name[KMALLOC_RANDOM_START + 11] = "kmalloc-rnd-12-" #sz, > -#define KMA_RAND_13(sz) KMA_RAND_12(sz) .name[KMALLOC_RANDOM_START + 12] = "kmalloc-rnd-13-" #sz, > -#define KMA_RAND_14(sz) KMA_RAND_13(sz) .name[KMALLOC_RANDOM_START + 13] = "kmalloc-rnd-14-" #sz, > -#define KMA_RAND_15(sz) KMA_RAND_14(sz) .name[KMALLOC_RANDOM_START + 14] = "kmalloc-rnd-15-" #sz, > -#define KMA_RAND_16(sz) KMA_RAND_15(sz) .name[KMALLOC_RANDOM_START + 15] = "kmalloc-rnd-16-" #sz, > +#define KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 1] = "kmalloc-rnd-01-" #sz, > +#define KMA_RAND_2(sz) KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 2] = "kmalloc-rnd-02-" #sz, > +#define KMA_RAND_3(sz) KMA_RAND_2(sz) .name[KMALLOC_RANDOM_START + 3] = "kmalloc-rnd-03-" #sz, > +#define KMA_RAND_4(sz) KMA_RAND_3(sz) .name[KMALLOC_RANDOM_START + 4] = "kmalloc-rnd-04-" #sz, > +#define KMA_RAND_5(sz) KMA_RAND_4(sz) .name[KMALLOC_RANDOM_START + 5] = "kmalloc-rnd-05-" #sz, > +#define KMA_RAND_6(sz) KMA_RAND_5(sz) .name[KMALLOC_RANDOM_START + 6] = "kmalloc-rnd-06-" #sz, > +#define KMA_RAND_7(sz) KMA_RAND_6(sz) .name[KMALLOC_RANDOM_START + 7] = "kmalloc-rnd-07-" #sz, > +#define KMA_RAND_8(sz) KMA_RAND_7(sz) .name[KMALLOC_RANDOM_START + 8] = "kmalloc-rnd-08-" #sz, > +#define KMA_RAND_9(sz) KMA_RAND_8(sz) .name[KMALLOC_RANDOM_START + 9] = "kmalloc-rnd-09-" #sz, > +#define KMA_RAND_10(sz) KMA_RAND_9(sz) .name[KMALLOC_RANDOM_START + 10] = "kmalloc-rnd-10-" #sz, > +#define KMA_RAND_11(sz) KMA_RAND_10(sz) .name[KMALLOC_RANDOM_START + 11] = "kmalloc-rnd-11-" #sz, > +#define KMA_RAND_12(sz) KMA_RAND_11(sz) .name[KMALLOC_RANDOM_START + 12] = "kmalloc-rnd-12-" #sz, > +#define KMA_RAND_13(sz) KMA_RAND_12(sz) .name[KMALLOC_RANDOM_START + 13] = "kmalloc-rnd-13-" #sz, > +#define KMA_RAND_14(sz) KMA_RAND_13(sz) .name[KMALLOC_RANDOM_START + 14] = "kmalloc-rnd-14-" #sz, > +#define KMA_RAND_15(sz) KMA_RAND_14(sz) .name[KMALLOC_RANDOM_START + 15] = "kmalloc-rnd-15-" #sz, > #else // CONFIG_RANDOM_KMALLOC_CACHES > #define KMALLOC_RANDOM_NAME(N, sz) > #endif > @@ -957,7 +956,7 @@ void __init create_kmalloc_caches(slab_flags_t flags) > /* > * Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined > */ > - for (type = KMALLOC_RANDOM_START; type < NR_KMALLOC_TYPES; type++) { > + for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) { > for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { > if (!kmalloc_caches[type][i]) > new_kmalloc_cache(i, type, flags); > > I've adjusted the code according to all suggestions I received and sent out the v5 patch. Thanks for the comments!