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Thu, 20 Jun 2024 13:56:27 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id WxnyJQs1dGaKVAAAD6G6ig (envelope-from ); Thu, 20 Jun 2024 13:56:27 +0000 Message-ID: Date: Thu, 20 Jun 2024 15:56:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 4/6] mm/slab: Introduce kmem_buckets_create() and family Content-Language: en-US To: Kees Cook Cc: "GONG, Ruiqi" , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , jvoisin , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Xiu Jianfeng , Suren Baghdasaryan , Kent Overstreet , Jann Horn , Matteo Rizzo , Thomas Graf , Herbert Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org, netdev@vger.kernel.org References: <20240619192131.do.115-kees@kernel.org> <20240619193357.1333772-4-kees@kernel.org> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: <20240619193357.1333772-4-kees@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 4D1A74000A X-Stat-Signature: e4snubtc43nari93e46o5fajmqbknm5i X-HE-Tag: 1718891790-496032 X-HE-Meta: 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 SB5CdQrC 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 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: List-Subscribe: List-Unsubscribe: On 6/19/24 9:33 PM, Kees Cook wrote: > Dedicated caches are available for fixed size allocations via > kmem_cache_alloc(), but for dynamically sized allocations there is only > the global kmalloc API's set of buckets available. This means it isn't > possible to separate specific sets of dynamically sized allocations into > a separate collection of caches. > > This leads to a use-after-free exploitation weakness in the Linux > kernel since many heap memory spraying/grooming attacks depend on using > userspace-controllable dynamically sized allocations to collide with > fixed size allocations that end up in same cache. > > While CONFIG_RANDOM_KMALLOC_CACHES provides a probabilistic defense > against these kinds of "type confusion" attacks, including for fixed > same-size heap objects, we can create a complementary deterministic > defense for dynamically sized allocations that are directly user > controlled. Addressing these cases is limited in scope, so isolating these > kinds of interfaces will not become an unbounded game of whack-a-mole. For > example, many pass through memdup_user(), making isolation there very > effective. > > In order to isolate user-controllable dynamically-sized > allocations from the common system kmalloc allocations, introduce > kmem_buckets_create(), which behaves like kmem_cache_create(). Introduce > kmem_buckets_alloc(), which behaves like kmem_cache_alloc(). Introduce > kmem_buckets_alloc_track_caller() for where caller tracking is > needed. Introduce kmem_buckets_valloc() for cases where vmalloc fallback > is needed. > > This can also be used in the future to extend allocation profiling's use > of code tagging to implement per-caller allocation cache isolation[1] > even for dynamic allocations. > > Memory allocation pinning[2] is still needed to plug the Use-After-Free > cross-allocator weakness, but that is an existing and separate issue > which is complementary to this improvement. Development continues for > that feature via the SLAB_VIRTUAL[3] series (which could also provide > guard pages -- another complementary improvement). > > Link: https://lore.kernel.org/lkml/202402211449.401382D2AF@keescook [1] > Link: https://googleprojectzero.blogspot.com/2021/10/how-simple-linux-kernel-memory.html [2] > Link: https://lore.kernel.org/lkml/20230915105933.495735-1-matteorizzo@google.com/ [3] > Signed-off-by: Kees Cook > --- > include/linux/slab.h | 13 ++++++++ > mm/slab_common.c | 78 ++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 91 insertions(+) > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index 8d0800c7579a..3698b15b6138 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -549,6 +549,11 @@ void *kmem_cache_alloc_lru_noprof(struct kmem_cache *s, struct list_lru *lru, > > void kmem_cache_free(struct kmem_cache *s, void *objp); > > +kmem_buckets *kmem_buckets_create(const char *name, unsigned int align, > + slab_flags_t flags, > + unsigned int useroffset, unsigned int usersize, > + void (*ctor)(void *)); I'd drop the ctor, I can't imagine how it would be used with variable-sized allocations. Probably also "align" doesn't make much sense since we're just copying the kmalloc cache sizes and its implicit alignment of any power-of-two allocations. I don't think any current kmalloc user would suddenly need either of those as you convert it to buckets, and definitely not any user converted automatically by the code tagging.