From patchwork Wed Oct 7 16:44:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 11821143 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4E5E01592 for ; Wed, 7 Oct 2020 16:45:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D74F9206BE for ; Wed, 7 Oct 2020 16:45:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="B6Y78U/C" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D74F9206BE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 55487900004; Wed, 7 Oct 2020 12:44:51 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 4B1C9900003; Wed, 7 Oct 2020 12:44:51 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3C90D900004; Wed, 7 Oct 2020 12:44:51 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0241.hostedemail.com [216.40.44.241]) by kanga.kvack.org (Postfix) with ESMTP id 0F437900003 for ; Wed, 7 Oct 2020 12:44:51 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id A0680180AD807 for ; Wed, 7 Oct 2020 16:44:50 +0000 (UTC) X-FDA: 77345703540.12.bat86_611504e271d0 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id 7E24818019982 for ; Wed, 7 Oct 2020 16:44:50 +0000 (UTC) X-Spam-Summary: 1,0,0,f50048ded6be6eea,d41d8cd98f00b204,daniel.vetter@ffwll.ch,,RULES_HIT:2:41:152:355:379:541:800:960:966:973:988:989:1260:1277:1311:1313:1314:1345:1359:1431:1437:1515:1516:1518:1535:1593:1594:1605:1730:1747:1777:1792:2194:2196:2198:2199:2200:2201:2393:2553:2559:2562:2693:2894:2901:2903:3138:3139:3140:3141:3142:3743:3865:3866:3867:3868:3870:3871:3872:3873:3874:4049:4120:4250:4321:4385:4605:5007:6117:6119:6261:6653:6742:7875:7903:8784:9165:10004:11026:11473:11658:11914:12043:12050:12291:12296:12297:12438:12517:12519:12555:12683:12895:12986:13161:13229:13846:13894:14096:14097:14394:14659:21080:21324:21444:21451:21627:21740:21795:21939:21966:21990:30003:30025:30051:30054:30064:30070:30090,0,RBL:209.85.221.66:@ffwll.ch:.lbl8.mailshell.net-62.8.0.100 66.201.201.201;04y816pfqxxwahb5k7sdxge48sudmocpk9jqqrm89ubyt746xxgi8i49feodqs6.qtib8zhubx9687qjtuiyxbnir695xbe1z59d3wqzdwfgctc3ctd88gngxt1seda.e-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Net check:no X-HE-Tag: bat86_611504e271d0 X-Filterd-Recvd-Size: 9309 Received: from mail-wr1-f66.google.com (mail-wr1-f66.google.com [209.85.221.66]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Wed, 7 Oct 2020 16:44:50 +0000 (UTC) Received: by mail-wr1-f66.google.com with SMTP id j2so2980968wrx.7 for ; Wed, 07 Oct 2020 09:44:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=lTBabPHcIR29EuHLrnWP/T+AJBtGm5KhLqQZnLrmjOk=; b=B6Y78U/CizMgqSGef4CNcX/ZAbAZRMLDFtT3Y2Q78gZFvfPXiYMD2psghmGlUqhbMN TaNgc3Hhm84l0AUdn7xg+cuNmGGercHUpnIZxgoDThibeFauGRMKYmgw5TdXCBtpaqci vToCVY3fwvV6lpfhfUPwrCrAx1SI7cFeAhgWA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=lTBabPHcIR29EuHLrnWP/T+AJBtGm5KhLqQZnLrmjOk=; b=lNmMIdC/qMOLiguZHaQqCuv6YI4YrtimGFZ6uU7GVlxU4Wz8qCPoKpBV2TdRQnOQQQ 9IYd5SPzYUWqG5cmIBn1BtNBGWJs82Its2UNKcDJyZb+/0oqZL0uRVhvBA+f6wUjaPbB Q50XkB9W2UZeOduFNTWtVhn40d0VvhYJZDGkOnje1pCHcFRTSFGrj4ejjmunmTVBXsNg B36gdrTr2s+pNoYv7ZQL0QOuAb+wgLs76DF+seiy4BmWKVCYP6OU5qx+nagZ93BYSek9 gYvdPRGjfd9Ry777ZUjT3YfP3Ae2Qc55/g5bF2coaKRIW5SUUOq2jmehZgYPfgTsRloN cSiA== X-Gm-Message-State: AOAM530MZ98O2rbIuzGODJgePqA9kUYfsxspjGjCFGlzVNHZ8shf5WFS zCgxirhpBxXEisfGnswi8x9yWw== X-Google-Smtp-Source: ABdhPJzDCkm6WtDsou+bjbEDH4oOgBt0QrRTTZxw26yFUl0NTd3VcvyK2uewsnDtS4YDsx0KJws7rA== X-Received: by 2002:a5d:6551:: with SMTP id z17mr4510042wrv.200.1602089088894; Wed, 07 Oct 2020 09:44:48 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id z191sm3332280wme.40.2020.10.07.09.44.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 09:44:48 -0700 (PDT) From: Daniel Vetter To: DRI Development , LKML Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-s390@vger.kernel.org, Daniel Vetter , Daniel Vetter , Jason Gunthorpe , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara Subject: [PATCH 11/13] mm: add unsafe_follow_pfn Date: Wed, 7 Oct 2020 18:44:24 +0200 Message-Id: <20201007164426.1812530-12-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201007164426.1812530-1-daniel.vetter@ffwll.ch> References: <20201007164426.1812530-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 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: Way back it was a reasonable assumptions that iomem mappings never change the pfn range they point at. But this has changed: - gpu drivers dynamically manage their memory nowadays, invalidating ptes with unmap_mapping_range when buffers get moved - contiguous dma allocations have moved from dedicated carvetouts to cma regions. This means if we miss the unmap the pfn might contain pagecache or anon memory (well anything allocated with GFP_MOVEABLE) - even /dev/mem now invalidates mappings when the kernel requests that iomem region when CONFIG_IO_STRICT_DEVMEM is set, see 3234ac664a87 ("/dev/mem: Revoke mappings when a driver claims the region") Accessing pfns obtained from ptes without holding all the locks is therefore no longer a good idea. Unfortunately there's some users where this is not fixable (like v4l userptr of iomem mappings) or involves a pile of work (vfio type1 iommu). For now annotate these as unsafe and splat appropriately. This patch adds an unsafe_follow_pfn, which later patches will then roll out to all appropriate places. Signed-off-by: Daniel Vetter Cc: Jason Gunthorpe Cc: Kees Cook Cc: Dan Williams Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: kvm@vger.kernel.org --- include/linux/mm.h | 2 ++ mm/memory.c | 32 +++++++++++++++++++++++++++++++- mm/nommu.c | 17 +++++++++++++++++ security/Kconfig | 13 +++++++++++++ 4 files changed, 63 insertions(+), 1 deletion(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 2a16631c1fda..ec8c90928fc9 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1653,6 +1653,8 @@ int follow_pte_pmd(struct mm_struct *mm, unsigned long address, pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp); int follow_pfn(struct vm_area_struct *vma, unsigned long address, unsigned long *pfn); +int unsafe_follow_pfn(struct vm_area_struct *vma, unsigned long address, + unsigned long *pfn); int follow_phys(struct vm_area_struct *vma, unsigned long address, unsigned int flags, unsigned long *prot, resource_size_t *phys); int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, diff --git a/mm/memory.c b/mm/memory.c index 8d467e23b44e..8db7ad1c261c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4821,7 +4821,12 @@ EXPORT_SYMBOL(follow_pte_pmd); * @address: user virtual address * @pfn: location to store found PFN * - * Only IO mappings and raw PFN mappings are allowed. + * Only IO mappings and raw PFN mappings are allowed. Note that callers must + * ensure coherency with pte updates by using a &mmu_notifier to follow updates. + * If this is not feasible, or the access to the @pfn is only very short term, + * use follow_pte_pmd() instead and hold the pagetable lock for the duration of + * the access instead. Any caller not following these requirements must use + * unsafe_follow_pfn() instead. * * Return: zero and the pfn at @pfn on success, -ve otherwise. */ @@ -4844,6 +4849,31 @@ int follow_pfn(struct vm_area_struct *vma, unsigned long address, } EXPORT_SYMBOL(follow_pfn); +/** + * unsafe_follow_pfn - look up PFN at a user virtual address + * @vma: memory mapping + * @address: user virtual address + * @pfn: location to store found PFN + * + * Only IO mappings and raw PFN mappings are allowed. + * + * Returns zero and the pfn at @pfn on success, -ve otherwise. + */ +int unsafe_follow_pfn(struct vm_area_struct *vma, unsigned long address, + unsigned long *pfn) +{ +#ifdef CONFIG_STRICT_FOLLOW_PFN + pr_info("unsafe follow_pfn usage rejected, see CONFIG_STRICT_FOLLOW_PFN\n"); + return -EINVAL; +#else + WARN_ONCE(1, "unsafe follow_pfn usage\n"); + add_taint(TAINT_USER, LOCKDEP_STILL_OK); + + return follow_pfn(vma, address, pfn); +#endif +} +EXPORT_SYMBOL(unsafe_follow_pfn); + #ifdef CONFIG_HAVE_IOREMAP_PROT int follow_phys(struct vm_area_struct *vma, unsigned long address, unsigned int flags, diff --git a/mm/nommu.c b/mm/nommu.c index 75a327149af1..3db2910f0d64 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -132,6 +132,23 @@ int follow_pfn(struct vm_area_struct *vma, unsigned long address, } EXPORT_SYMBOL(follow_pfn); +/** + * unsafe_follow_pfn - look up PFN at a user virtual address + * @vma: memory mapping + * @address: user virtual address + * @pfn: location to store found PFN + * + * Only IO mappings and raw PFN mappings are allowed. + * + * Returns zero and the pfn at @pfn on success, -ve otherwise. + */ +int unsafe_follow_pfn(struct vm_area_struct *vma, unsigned long address, + unsigned long *pfn) +{ + return follow_pfn(vma, address, pfn); +} +EXPORT_SYMBOL(unsafe_follow_pfn); + LIST_HEAD(vmap_area_list); void vfree(const void *addr) diff --git a/security/Kconfig b/security/Kconfig index 7561f6f99f1d..48945402e103 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -230,6 +230,19 @@ config STATIC_USERMODEHELPER_PATH If you wish for all usermode helper programs to be disabled, specify an empty string here (i.e. ""). +config STRICT_FOLLOW_PFN + bool "Disable unsafe use of follow_pfn" + depends on MMU + help + Some functionality in the kernel follows userspace mappings to iomem + ranges in an unsafe matter. Examples include v4l userptr for zero-copy + buffers sharing. + + If this option is switched on, such access is rejected. Only enable + this option when you must run userspace which requires this. + + If in doubt, say Y. + source "security/selinux/Kconfig" source "security/smack/Kconfig" source "security/tomoyo/Kconfig"