linux-kernel - [PATCH v3 2/2] dma-mapping: Fix dma_pgprot() for unencrypted coherent pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190917130115.51748-3-thomas_os@shipmail.org>
Date:   Tue, 17 Sep 2019 15:01:15 +0200
From:   Thomas Hellström (VMware) 
        <thomas_os@...pmail.org>
To:     linux-kernel@...r.kernel.org
Cc:     pv-drivers@...are.com, linux-graphics-maintainer@...are.com,
        x86@...nel.org, Thomas Hellstrom <thellstrom@...are.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Christoph Hellwig <hch@...radead.org>,
        Christian König <christian.koenig@....com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: [PATCH v3 2/2] dma-mapping: Fix dma_pgprot() for unencrypted coherent pages

From: Thomas Hellstrom <thellstrom@...are.com>

When dma_mmap_coherent() sets up a mapping to unencrypted coherent memory
under SEV encryption and sometimes under SME encryption, it will actually
set up an encrypted mapping rather than an unencrypted, causing devices
that DMAs from that memory to read encrypted contents. Fix this.

When force_dma_unencrypted() returns true, the linear kernel map of the
coherent pages have had the encryption bit explicitly cleared and the
page content is unencrypted. Make sure that any additional PTEs we set
up to these pages also have the encryption bit cleared by having
dma_pgprot() return a protection with the encryption bit cleared in this
case.

Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Christoph Hellwig <hch@...radead.org>
Cc: Christian König <christian.koenig@....com>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Thomas Hellstrom <thellstrom@...are.com>
---
 kernel/dma/mapping.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index b0038ca3aa92..2b499dcae74f 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -157,6 +157,8 @@ EXPORT_SYMBOL(dma_get_sgtable_attrs);
  */
 pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs)
 {
+	if (force_dma_unencrypted(dev))
+		prot = pgprot_decrypted(prot);
 	if (dev_is_dma_coherent(dev) ||
 	    (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) &&
              (attrs & DMA_ATTR_NON_CONSISTENT)))
-- 
2.20.1