From patchwork Tue Apr 13 09:49:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 12199897 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=-16.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 B7251C433B4 for ; Tue, 13 Apr 2021 09:49:46 +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 7F766613AB for ; Tue, 13 Apr 2021 09:49:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F766613AB 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 DACD96E3D3; Tue, 13 Apr 2021 09:49:45 +0000 (UTC) Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by gabe.freedesktop.org (Postfix) with ESMTPS id EA14F6E3D3 for ; Tue, 13 Apr 2021 09:49:44 +0000 (UTC) Received: by mail-wr1-x42a.google.com with SMTP id h4so6745465wrt.12 for ; Tue, 13 Apr 2021 02:49:44 -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:mime-version :content-transfer-encoding; bh=K0Wz4wS6e0aG0cvyt2mlje2DcLt3LX0aNr+PuIP3yAo=; b=VDHCqI39fbJhMeJM40wNJA8oXtVOGPIIxoeXUvLsl5G5sOOsnZlDAAK96YK1sn02IL kTSkpEsiLF721ronw4jBAQm0gcNbtEIMElO/fuQO1rnZqp+7EUDFiggVCqlibjyNwfAk kLgOMCS2gAJC/sYwflGznj3J6jViuWafmq2pw= 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:mime-version :content-transfer-encoding; bh=K0Wz4wS6e0aG0cvyt2mlje2DcLt3LX0aNr+PuIP3yAo=; b=tE9CUYda3SOvUoljratwvo6uI0Rq+7Tmt5NFigHCT45SUwwDYlzS9+tCNfTatDvI35 kwFjyCjPS5X0TYOy9GHfymKtbTviqhXtIH9DChr1NCTaT0Yt+llWaLemq+l1V0dUtcfW Pc8xRnw6Yc8iXKXoK44V3swTowTzzeaUK2ZOIX3p/4zrpwnnKpkvdkiugga1XI8jwuyu fLw12JrnC2bei9JP8kdl0cpPXqROiZHLnGh7wszVw6EfRTVCmaqAFJIsO/gqmmTHFmnX pHE9VI1r8wmH/6qSbxcUzq950Nvh3gWxpJTeHyWzfX8QFmBTM+rgQ38NRiZXmwHEVwQ7 Yd3A== X-Gm-Message-State: AOAM531w23ULn3mqm3Pgc+4aBQr+vFQGXm8+RI5RYnNxzQOM7ZTFfa3l lm+EqbgybXCBDOj0TpfRa/qJQlQJvt9ajQ== X-Google-Smtp-Source: ABdhPJy08kynhMrxZ4xKGPt8RloTLXu41rqTu0VZP+7WUKfkm5rGSC+Gwa/9CsBzIcyoI8A04EkNkQ== X-Received: by 2002:adf:fe4f:: with SMTP id m15mr25789730wrs.67.1618307383685; Tue, 13 Apr 2021 02:49:43 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id x15sm1945964wmi.41.2021.04.13.02.49.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Apr 2021 02:49:43 -0700 (PDT) From: Daniel Vetter To: DRI Development Subject: [PATCH 1/3] dma-buf: Require VM_PFNMAP vma for mmap Date: Tue, 13 Apr 2021 11:49:35 +0200 Message-Id: <20210413094937.3736541-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.31.0 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: Daniel Vetter , Intel Graphics Development , Matthew Wilcox , linaro-mm-sig@lists.linaro.org, Jason Gunthorpe , Daniel Vetter , Suren Baghdasaryan , =?utf-8?q?Christian_K=C3=B6nig?= , linux-media@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" tldr; DMA buffers aren't normal memory, expecting that you can use them like that (like calling get_user_pages works, or that they're accounting like any other normal memory) cannot be guaranteed. Since some userspace only runs on integrated devices, where all buffers are actually all resident system memory, there's a huge temptation to assume that a struct page is always present and useable like for any more pagecache backed mmap. This has the potential to result in a uapi nightmare. To stop this gap require that DMA buffer mmaps are VM_PFNMAP, which blocks get_user_pages and all the other struct page based infrastructure for everyone. In spirit this is the uapi counterpart to the kernel-internal CONFIG_DMABUF_DEBUG. Motivated by a recent patch which wanted to swich the system dma-buf heap to vm_insert_page instead of vm_insert_pfn. v2: Jason brought up that we also want to guarantee that all ptes have the pte_special flag set, to catch fast get_user_pages (on architectures that support this). Allowing VM_MIXEDMAP (like VM_SPECIAL does) would still allow vm_insert_page, but limiting to VM_PFNMAP will catch that. From auditing the various functions to insert pfn pte entires (vm_insert_pfn_prot, remap_pfn_range and all it's callers like dma_mmap_wc) it looks like VM_PFNMAP is already required anyway, so this should be the correct flag to check for. References: https://lore.kernel.org/lkml/CAKMK7uHi+mG0z0HUmNt13QCCvutuRVjpcR0NjRL12k-WbWzkRg@mail.gmail.com/ Acked-by: Christian König Cc: Jason Gunthorpe Cc: Suren Baghdasaryan Cc: Matthew Wilcox Cc: John Stultz Signed-off-by: Daniel Vetter Cc: Sumit Semwal Cc: "Christian König" Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org --- drivers/dma-buf/dma-buf.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index f264b70c383e..06cb1d2e9fdc 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -127,6 +127,7 @@ static struct file_system_type dma_buf_fs_type = { static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) { struct dma_buf *dmabuf; + int ret; if (!is_dma_buf_file(file)) return -EINVAL; @@ -142,7 +143,11 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) dmabuf->size >> PAGE_SHIFT) return -EINVAL; - return dmabuf->ops->mmap(dmabuf, vma); + ret = dmabuf->ops->mmap(dmabuf, vma); + + WARN_ON(!(vma->vm_flags & VM_PFNMAP)); + + return ret; } static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence) @@ -1244,6 +1249,8 @@ EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access); int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, unsigned long pgoff) { + int ret; + if (WARN_ON(!dmabuf || !vma)) return -EINVAL; @@ -1264,7 +1271,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, vma_set_file(vma, dmabuf->file); vma->vm_pgoff = pgoff; - return dmabuf->ops->mmap(dmabuf, vma); + ret = dmabuf->ops->mmap(dmabuf, vma); + + WARN_ON(!(vma->vm_flags & VM_PFNMAP)); + + return ret; } EXPORT_SYMBOL_GPL(dma_buf_mmap);