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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id o4sm2006223qko.120.2020.10.07.10.36.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 10:36:47 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kQDMt-00110d-DV; Wed, 07 Oct 2020 14:36:47 -0300 Date: Wed, 7 Oct 2020 14:36:47 -0300 From: Jason Gunthorpe To: Daniel Vetter Cc: DRI Development , LKML , 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 , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Jan Kara Subject: Re: [PATCH 11/13] mm: add unsafe_follow_pfn Message-ID: <20201007173647.GW5177@ziepe.ca> References: <20201007164426.1812530-1-daniel.vetter@ffwll.ch> <20201007164426.1812530-12-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201007164426.1812530-12-daniel.vetter@ffwll.ch> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 07, 2020 at 06:44:24PM +0200, Daniel Vetter wrote: > 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(-) Makes sense to me. I wonder if we could change the original follow_pfn to require the ptep and then lockdep_assert_held() it against the page table lock? > +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"); Wonder if we can print something useful here, like the current PID/process name? > 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 I would probably invert this CONFIG_ALLOW_UNSAFE_FOLLOW_PFN default n Jason From mboxrd@z Thu Jan 1 00:00:00 1970 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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6FC78C41604 for ; 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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id o4sm2006223qko.120.2020.10.07.10.36.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 10:36:47 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kQDMt-00110d-DV; Wed, 07 Oct 2020 14:36:47 -0300 Date: Wed, 7 Oct 2020 14:36:47 -0300 From: Jason Gunthorpe To: Daniel Vetter Subject: Re: [PATCH 11/13] mm: add unsafe_follow_pfn Message-ID: <20201007173647.GW5177@ziepe.ca> References: <20201007164426.1812530-1-daniel.vetter@ffwll.ch> <20201007164426.1812530-12-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201007164426.1812530-12-daniel.vetter@ffwll.ch> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201007_133650_405233_450EFE5A X-CRM114-Status: GOOD ( 25.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, John Hubbard , LKML , DRI Development , linux-mm@kvack.org, =?utf-8?B?SsOpcsO0bWU=?= Glisse , Daniel Vetter , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gV2VkLCBPY3QgMDcsIDIwMjAgYXQgMDY6NDQ6MjRQTSArMDIwMCwgRGFuaWVsIFZldHRlciB3 cm90ZToKPiBXYXkgYmFjayBpdCB3YXMgYSByZWFzb25hYmxlIGFzc3VtcHRpb25zIHRoYXQgaW9t ZW0gbWFwcGluZ3MgbmV2ZXIKPiBjaGFuZ2UgdGhlIHBmbiByYW5nZSB0aGV5IHBvaW50IGF0LiBC dXQgdGhpcyBoYXMgY2hhbmdlZDoKPiAKPiAtIGdwdSBkcml2ZXJzIGR5bmFtaWNhbGx5IG1hbmFn ZSB0aGVpciBtZW1vcnkgbm93YWRheXMsIGludmFsaWRhdGluZwo+IHB0ZXMgd2l0aCB1bm1hcF9t YXBwaW5nX3JhbmdlIHdoZW4gYnVmZmVycyBnZXQgbW92ZWQKPiAKPiAtIGNvbnRpZ3VvdXMgZG1h IGFsbG9jYXRpb25zIGhhdmUgbW92ZWQgZnJvbSBkZWRpY2F0ZWQgY2FydmV0b3V0cyB0bwo+IGNt YSByZWdpb25zLiBUaGlzIG1lYW5zIGlmIHdlIG1pc3MgdGhlIHVubWFwIHRoZSBwZm4gbWlnaHQg Y29udGFpbgo+IHBhZ2VjYWNoZSBvciBhbm9uIG1lbW9yeSAod2VsbCBhbnl0aGluZyBhbGxvY2F0 ZWQgd2l0aCBHRlBfTU9WRUFCTEUpCj4gCj4gLSBldmVuIC9kZXYvbWVtIG5vdyBpbnZhbGlkYXRl cyBtYXBwaW5ncyB3aGVuIHRoZSBrZXJuZWwgcmVxdWVzdHMgdGhhdAo+IGlvbWVtIHJlZ2lvbiB3 aGVuIENPTkZJR19JT19TVFJJQ1RfREVWTUVNIGlzIHNldCwgc2VlIDMyMzRhYzY2NGE4Nwo+ICgi L2Rldi9tZW06IFJldm9rZSBtYXBwaW5ncyB3aGVuIGEgZHJpdmVyIGNsYWltcyB0aGUgcmVnaW9u IikKPiAKPiBBY2Nlc3NpbmcgcGZucyBvYnRhaW5lZCBmcm9tIHB0ZXMgd2l0aG91dCBob2xkaW5n IGFsbCB0aGUgbG9ja3MgaXMKPiB0aGVyZWZvcmUgbm8gbG9uZ2VyIGEgZ29vZCBpZGVhLgo+IAo+ IFVuZm9ydHVuYXRlbHkgdGhlcmUncyBzb21lIHVzZXJzIHdoZXJlIHRoaXMgaXMgbm90IGZpeGFi bGUgKGxpa2UgdjRsCj4gdXNlcnB0ciBvZiBpb21lbSBtYXBwaW5ncykgb3IgaW52b2x2ZXMgYSBw aWxlIG9mIHdvcmsgKHZmaW8gdHlwZTEKPiBpb21tdSkuIEZvciBub3cgYW5ub3RhdGUgdGhlc2Ug YXMgdW5zYWZlIGFuZCBzcGxhdCBhcHByb3ByaWF0ZWx5Lgo+IAo+IFRoaXMgcGF0Y2ggYWRkcyBh biB1bnNhZmVfZm9sbG93X3Bmbiwgd2hpY2ggbGF0ZXIgcGF0Y2hlcyB3aWxsIHRoZW4KPiByb2xs IG91dCB0byBhbGwgYXBwcm9wcmlhdGUgcGxhY2VzLgo+IAo+IFNpZ25lZC1vZmYtYnk6IERhbmll bCBWZXR0ZXIgPGRhbmllbC52ZXR0ZXJAaW50ZWwuY29tPgo+IENjOiBKYXNvbiBHdW50aG9ycGUg PGpnZ0B6aWVwZS5jYT4KPiBDYzogS2VlcyBDb29rIDxrZWVzY29va0BjaHJvbWl1bS5vcmc+Cj4g Q2M6IERhbiBXaWxsaWFtcyA8ZGFuLmoud2lsbGlhbXNAaW50ZWwuY29tPgo+IENjOiBBbmRyZXcg TW9ydG9uIDxha3BtQGxpbnV4LWZvdW5kYXRpb24ub3JnPgo+IENjOiBKb2huIEh1YmJhcmQgPGpo dWJiYXJkQG52aWRpYS5jb20+Cj4gQ2M6IErDqXLDtG1lIEdsaXNzZSA8amdsaXNzZUByZWRoYXQu Y29tPgo+IENjOiBKYW4gS2FyYSA8amFja0BzdXNlLmN6Pgo+IENjOiBEYW4gV2lsbGlhbXMgPGRh bi5qLndpbGxpYW1zQGludGVsLmNvbT4KPiBDYzogbGludXgtbW1Aa3ZhY2sub3JnCj4gQ2M6IGxp bnV4LWFybS1rZXJuZWxAbGlzdHMuaW5mcmFkZWFkLm9yZwo+IENjOiBsaW51eC1zYW1zdW5nLXNv Y0B2Z2VyLmtlcm5lbC5vcmcKPiBDYzogbGludXgtbWVkaWFAdmdlci5rZXJuZWwub3JnCj4gQ2M6 IGt2bUB2Z2VyLmtlcm5lbC5vcmcKPiAtLS0KPiAgaW5jbHVkZS9saW51eC9tbS5oIHwgIDIgKysK PiAgbW0vbWVtb3J5LmMgICAgICAgIHwgMzIgKysrKysrKysrKysrKysrKysrKysrKysrKysrKysr Ky0KPiAgbW0vbm9tbXUuYyAgICAgICAgIHwgMTcgKysrKysrKysrKysrKysrKysKPiAgc2VjdXJp dHkvS2NvbmZpZyAgIHwgMTMgKysrKysrKysrKysrKwo+ICA0IGZpbGVzIGNoYW5nZWQsIDYzIGlu c2VydGlvbnMoKyksIDEgZGVsZXRpb24oLSkKCk1ha2VzIHNlbnNlIHRvIG1lLgoKSSB3b25kZXIg aWYgd2UgY291bGQgY2hhbmdlIHRoZSBvcmlnaW5hbCBmb2xsb3dfcGZuIHRvIHJlcXVpcmUgdGhl CnB0ZXAgYW5kIHRoZW4gbG9ja2RlcF9hc3NlcnRfaGVsZCgpIGl0IGFnYWluc3QgdGhlIHBhZ2Ug dGFibGUgbG9jaz8KCj4gK2ludCB1bnNhZmVfZm9sbG93X3BmbihzdHJ1Y3Qgdm1fYXJlYV9zdHJ1 Y3QgKnZtYSwgdW5zaWduZWQgbG9uZyBhZGRyZXNzLAo+ICsJdW5zaWduZWQgbG9uZyAqcGZuKQo+ ICt7Cj4gKyNpZmRlZiBDT05GSUdfU1RSSUNUX0ZPTExPV19QRk4KPiArCXByX2luZm8oInVuc2Fm ZSBmb2xsb3dfcGZuIHVzYWdlIHJlamVjdGVkLCBzZWUKPiBDT05GSUdfU1RSSUNUX0ZPTExPV19Q Rk5cbiIpOwoKV29uZGVyIGlmIHdlIGNhbiBwcmludCBzb21ldGhpbmcgdXNlZnVsIGhlcmUsIGxp a2UgdGhlIGN1cnJlbnQKUElEL3Byb2Nlc3MgbmFtZT8KCj4gZGlmZiAtLWdpdCBhL3NlY3VyaXR5 L0tjb25maWcgYi9zZWN1cml0eS9LY29uZmlnCj4gaW5kZXggNzU2MWY2Zjk5ZjFkLi40ODk0NTQw MmUxMDMgMTAwNjQ0Cj4gLS0tIGEvc2VjdXJpdHkvS2NvbmZpZwo+ICsrKyBiL3NlY3VyaXR5L0tj b25maWcKPiBAQCAtMjMwLDYgKzIzMCwxOSBAQCBjb25maWcgU1RBVElDX1VTRVJNT0RFSEVMUEVS X1BBVEgKPiAgCSAgSWYgeW91IHdpc2ggZm9yIGFsbCB1c2VybW9kZSBoZWxwZXIgcHJvZ3JhbXMg dG8gYmUgZGlzYWJsZWQsCj4gIAkgIHNwZWNpZnkgYW4gZW1wdHkgc3RyaW5nIGhlcmUgKGkuZS4g IiIpLgo+ICAKPiArY29uZmlnIFNUUklDVF9GT0xMT1dfUEZOCj4gKwlib29sICJEaXNhYmxlIHVu c2FmZSB1c2Ugb2YgZm9sbG93X3BmbiIKPiArCWRlcGVuZHMgb24gTU1VCgpJIHdvdWxkIHByb2Jh Ymx5IGludmVydCB0aGlzIENPTkZJR19BTExPV19VTlNBRkVfRk9MTE9XX1BGTgpkZWZhdWx0IG4K Ckphc29uCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwps aW51eC1hcm0ta2VybmVsIG1haWxpbmcgbGlzdApsaW51eC1hcm0ta2VybmVsQGxpc3RzLmluZnJh ZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9saW51 eC1hcm0ta2VybmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.5 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 autolearn=unavailable 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 900FEC433E7 for ; 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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id o4sm2006223qko.120.2020.10.07.10.36.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 10:36:47 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kQDMt-00110d-DV; Wed, 07 Oct 2020 14:36:47 -0300 Date: Wed, 7 Oct 2020 14:36:47 -0300 From: Jason Gunthorpe To: Daniel Vetter Subject: Re: [PATCH 11/13] mm: add unsafe_follow_pfn Message-ID: <20201007173647.GW5177@ziepe.ca> References: <20201007164426.1812530-1-daniel.vetter@ffwll.ch> <20201007164426.1812530-12-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201007164426.1812530-12-daniel.vetter@ffwll.ch> X-Mailman-Approved-At: Thu, 08 Oct 2020 07:20:54 +0000 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-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, John Hubbard , LKML , DRI Development , linux-mm@kvack.org, =?utf-8?B?SsOpcsO0bWU=?= Glisse , Daniel Vetter , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Content-Type: text/plain; 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