From patchwork Fri Oct 23 12:21:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 11853147 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC665C64E7A for ; Fri, 23 Oct 2020 12:24:21 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8BB9521527 for ; Fri, 23 Oct 2020 12:24:21 +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="K0cS0ybR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8BB9521527 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 363386E5D5; Fri, 23 Oct 2020 12:23:09 +0000 (UTC) Received: from mail-wr1-x441.google.com (mail-wr1-x441.google.com [IPv6:2a00:1450:4864:20::441]) by gabe.freedesktop.org (Postfix) with ESMTPS id 87A976E5D5 for ; Fri, 23 Oct 2020 12:23:07 +0000 (UTC) Received: by mail-wr1-x441.google.com with SMTP id n18so1579235wrs.5 for ; Fri, 23 Oct 2020 05:23:07 -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=Jw8O4zHShCAt4bi/mdSwE8pqaQ/Ci7nnAmM3jj6tKas=; b=K0cS0ybRn+oowL57X6Nq5A66q23biV6d8Mh7nGNYpraDsikoql8NXlqFHPQVPGQZEq ZhmiEFHW8LcIIsLLB04p9O5em1Gy5Y5hrhfhfjs2YroaC/WrwZiQyslSzwbv6NtWleY1 RjNBNdVMAomvkHW50DBDpEmjI0t0ipkA/M7JE= 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=Jw8O4zHShCAt4bi/mdSwE8pqaQ/Ci7nnAmM3jj6tKas=; b=uGSZM+SsyYM5K4YT+yFY/bCwnp1XztA+g848xX28Yv0PtLv4U2X3VWhU6avi/JaUhw jA+EHumIQSL4R6JIcX8X5ZAUDdM0kyHbniXnqtNRUEOy3OE4BF8Ch4I/rJSftY746X9/ z6TxbPGelEKMjH+vWBRIFoLj8/4XpYKxFQfysLjFhi4LanvJKttuFMY7gVJBqC6C7KgT ulXBje4plIfGpqsHubDfQGNmrhuY7fqzHgxR2KsmySuaubOV6fCTrDqi33rkuJrs/llA WCxvauq8Fg7Ts4JWEVBkQuN726jr+R255nliywUuG3KK10X2WxbN11tLZe10kZYj9Vwt VQkA== X-Gm-Message-State: AOAM532JRSYN6bem6pLoxoo7ITSWmV8xablpYkbZfahox5NZkwhZgeKD hqHf9Z7aZ0ZnK/ufeqcfDTPy/nbmCJfHu92T X-Google-Smtp-Source: ABdhPJyHNrzVnBA/1XZbDotdv4KJ/xMo2zJVR986ilnB2l49QrGJnJFipT6hqx9IUcARiSC9qfVVjQ== X-Received: by 2002:a5d:6551:: with SMTP id z17mr2352471wrv.266.1603455785885; Fri, 23 Oct 2020 05:23:05 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id y4sm3056484wrp.74.2020.10.23.05.23.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Oct 2020 05:23:05 -0700 (PDT) From: Daniel Vetter To: DRI Development Subject: [PATCH 37/65] mm: Add unsafe_follow_pfn Date: Fri, 23 Oct 2020 14:21:48 +0200 Message-Id: <20201023122216.2373294-37-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201023122216.2373294-1-daniel.vetter@ffwll.ch> References: <20201021163242.1458885-1-daniel.vetter@ffwll.ch> <20201023122216.2373294-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, linux-mm@kvack.org, Daniel Vetter , Intel Graphics Development , Jason Gunthorpe , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , John Hubbard , Daniel Vetter , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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 Signed-off-by: Daniel Vetter --- 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 1b46eae3b703..9a2ec07ff20b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4788,7 +4788,12 @@ 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. */ @@ -4811,6 +4816,31 @@ 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"