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: 12199903 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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 ED18CC433ED for ; Tue, 13 Apr 2021 09:49:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D5F5E613B7 for ; Tue, 13 Apr 2021 09:49:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240464AbhDMJuF (ORCPT ); Tue, 13 Apr 2021 05:50:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240518AbhDMJuE (ORCPT ); Tue, 13 Apr 2021 05:50:04 -0400 Received: from mail-wr1-x432.google.com (mail-wr1-x432.google.com [IPv6:2a00:1450:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3DB2C061574 for ; Tue, 13 Apr 2021 02:49:44 -0700 (PDT) Received: by mail-wr1-x432.google.com with SMTP id c15so6820956wro.13 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=pLaAEeCpFL/z7h75750G98W873UL9hc4FxJ01OAbFjWv9EVkWrzEpFl6vXgQRbE+hc VS9iG41ENFMR4xg+JdZkZ5MXJJ0+gSY0jtzfYBxmUST2IUNerknDqIXsC/BG11Hba0to OGf/R/0gS/0d+TrqvkZHhrhNqlyivMc0GF6EvcNbvakpRl9j/Ikrre2seesGDjVDxRTS K4ng5YOWrLOLH+YNfdrBKxgiSGngvHu9tMHH6iaj/hJjszO1QBfp1bV20z3PK6vE0+P7 +3sILHy62igsD40eQIXOvGfS8kZ4QW7qxw+Ez9X3LZCOdt8ltLAS34NqRhfX/RN0Fh8/ yu3g== X-Gm-Message-State: AOAM531kRfMpP9lCVeQK5IvTij8dnGi/dbicLF/fVpt/O8JpUPIZCxn1 kO9ObehcHPX5TQqVNfk/1lv0vQ== 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 Cc: Intel Graphics Development , Daniel Vetter , =?utf-8?q?Christian_K=C3=B6nig?= , Jason Gunthorpe , Suren Baghdasaryan , Matthew Wilcox , John Stultz , Daniel Vetter , Sumit Semwal , linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org 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 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org 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);