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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA428C3ABDD for ; Wed, 14 May 2025 17:39:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 62FC16B01A2; Wed, 14 May 2025 13:39:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5DDF36B01F6; Wed, 14 May 2025 13:39:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 42F1B6B01F7; Wed, 14 May 2025 13:39:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 1A5AF6B01A2 for ; Wed, 14 May 2025 13:39:30 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 8CD861D0365 for ; Wed, 14 May 2025 17:39:31 +0000 (UTC) X-FDA: 83442225342.15.3F8C674 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf26.hostedemail.com (Postfix) with ESMTP id E9092140002 for ; Wed, 14 May 2025 17:39:28 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=U8+ok9Xj; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf26.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1747244369; a=rsa-sha256; cv=none; b=vF7VlSjmWAvUsK4MjRAzsR+ZI8y5vJlL+qi3ocKjRVWSbyT+Z6egGbSGmYhsT6U9Az4cUG IcHe0IBTbp7XzpSGnaZ5TyKiMpiCjPMgumXmLmDkJE+da9LCwsfloEf4VdonNJskfI5/AU tAGmUICcOd5it3m9PPAQIubD1M3HXMY= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=U8+ok9Xj; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf26.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1747244369; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Vk9Xh8XvArJD+LRx2+377usNjpdXE43bkUgaFQ0lI2A=; b=iliHSztud3PXGNCoarr5iY4yszwDiZW8kIIlVygBs8s3mTRcgv14zbfDWvPDZljHAPJ/Xq qrY74TVGm1SPI1DJ4i5pbixeiTg8aiFCVaISKp7tl/UGce90LctD7OVZ+u7MN91P8S/Y7Y 3Pifz/pUCzMKy6d7DiK0twC+FNDgaOk= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1747244368; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=Vk9Xh8XvArJD+LRx2+377usNjpdXE43bkUgaFQ0lI2A=; b=U8+ok9XjkioIqI3DdL40Qk2yrLW7AxXk+VBQqXF25RaUzxrrb/EBzTYpYJCkhkotExB5HQ oI60ymPmIK4EvQpf+PYAeA/2kPA49v5xwPtGDwBWQSIQinZoWTtHuLjkUfwLeJ5eiqL4JE RyjRbABvoCvEhCs6CSOxyyF+vlmdgtE= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-682-7vhBW1TkNTGN7yzQA3FcJA-1; Wed, 14 May 2025 13:39:27 -0400 X-MC-Unique: 7vhBW1TkNTGN7yzQA3FcJA-1 X-Mimecast-MFC-AGG-ID: 7vhBW1TkNTGN7yzQA3FcJA_1747244366 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-43cf44b66f7so434425e9.1 for ; Wed, 14 May 2025 10:39:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1747244366; x=1747849166; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=Vk9Xh8XvArJD+LRx2+377usNjpdXE43bkUgaFQ0lI2A=; b=R6aCalvLzX6tVAKz9K4T2LQpZXD7kTSqKt4+LgQBhBx+47L0MnOPibh+9auUYd1TeJ XNSSwHK0xW3awji4mlQpVzIQbv9R+je6MemXkvD5wv1tJJJnZ5slwRYBxHsYx2F+N+Or f+/uO4Nh5Zn9EKqDfLakM2TJiWP0hc82klBzzHiB596x989C+UvrvsikLSyQoqWMg/TF eeyyJFVuj7duD9vcqinolDNTcLVsvdMH+anA4znaoywAzy/92ijjcyLvRHLnJYnckfzJ WZXojekAjoOfkwsOxWVEQxWcAIykH9tCF6IhWyLQrXIZ54faXDpykKO4dfxkP3ceGG/0 pWuQ== X-Forwarded-Encrypted: i=1; AJvYcCUqtWw/jcN1Nx/0OZeYTvoqRQr5cyAqwugbZqWkQ4ppCtpYG2IB+TflPz0+UAyt6fh0tS1iFzvWjg==@kvack.org X-Gm-Message-State: AOJu0Yxq8RpJP+1FtR37ByJ31vBdssp4EqGcOWWL09bb1RZFIiSWma/V 9VF0DRcIqZIm1mR280QDvSL5VjgPYKG62KYi290uMY22SGdafCvsecKEbwVoun7uHF9lsQe8Dwa PvKUzjyarQgY3S4TyxXyf08BV26USsoPo8ecW8ftcCw8d+uNO X-Gm-Gg: ASbGncsjL6jd/t1484eooVMTSc32iVKqJAuYHUxFbZEGS0rC+1EbKdAIA0yRNlk+1U7 dHNdW9NGEI5A8A+hTRDoDTTRI65SlAKOxaGj1ytu/C0PqNrfksww00UjwFAqEiGfHN6140whz32 l5f39gYO01pyQeJ3SeVO8f3S4kzOxORtMXavwDmj5bcPeEG0j5wXI8WvTfMQhGjL8OeO/aukq/Y ZucFgFBLhLd5AMSaWVlQ+M405qU9r/T9H/oZyx42pI4/QpumyggdoCC0Z2i2ZHje0i/J307zyb1 Y0SMQ07J8xIp4cVUNPaPLfINaFws4ke256emTgn7b6fgmfU689qmanwiL4UqetzcB8F9lZvVS6I B4TUq30UYMsmtezJmgqpE1XDrl0xOSdFap5/q6z4= X-Received: by 2002:a05:600c:358b:b0:43d:42b:e186 with SMTP id 5b1f17b1804b1-442f20e8141mr39825295e9.8.1747244365835; Wed, 14 May 2025 10:39:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHQHpSZjD5VZhXH8bp5bUHN2OiSM/BgOW5x2KH7T+UY5v92NfRDDAwGcMz7DinxHmUBaaQbew== X-Received: by 2002:a05:600c:358b:b0:43d:42b:e186 with SMTP id 5b1f17b1804b1-442f20e8141mr39825125e9.8.1747244365413; Wed, 14 May 2025 10:39:25 -0700 (PDT) Received: from ?IPV6:2003:d8:2f15:6200:d485:1bcd:d708:f5df? (p200300d82f156200d4851bcdd708f5df.dip0.t-ipconnect.de. [2003:d8:2f15:6200:d485:1bcd:d708:f5df]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a1f5a2d96csm20462242f8f.69.2025.05.14.10.39.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 May 2025 10:39:24 -0700 (PDT) Message-ID: Date: Wed, 14 May 2025 19:39:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 08/17] KVM: guest_memfd: Check that userspace_addr and fd+offset refer to same range To: Fuad Tabba , kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com References: <20250513163438.3942405-1-tabba@google.com> <20250513163438.3942405-9-tabba@google.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250513163438.3942405-9-tabba@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: ycO_0kKH6rRWlFOjKLhGq5f0um6Jlj165cyk7ydkmZk_1747244366 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: E9092140002 X-Rspam-User: X-Stat-Signature: tfbxbdsuznhqyfiixcawx6jp1xyghgcq X-HE-Tag: 1747244368-160633 X-HE-Meta: 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 LVlgk5kU 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 13.05.25 18:34, Fuad Tabba wrote: > From: Ackerley Tng > > On binding of a guest_memfd with a memslot, check that the slot's > userspace_addr and the requested fd and offset refer to the same memory > range. > > This check is best-effort: nothing prevents userspace from later mapping > other memory to the same provided in slot->userspace_addr and breaking > guest operation. > > Suggested-by: David Hildenbrand > Suggested-by: Sean Christopherson > Suggested-by: Yan Zhao > Signed-off-by: Ackerley Tng > Signed-off-by: Fuad Tabba > --- > virt/kvm/guest_memfd.c | 37 ++++++++++++++++++++++++++++++++++--- > 1 file changed, 34 insertions(+), 3 deletions(-) > > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > index 8e6d1866b55e..2f499021df66 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -556,6 +556,32 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args) > return __kvm_gmem_create(kvm, size, flags); > } > > +static bool kvm_gmem_is_same_range(struct kvm *kvm, > + struct kvm_memory_slot *slot, > + struct file *file, loff_t offset) > +{ > + struct mm_struct *mm = kvm->mm; > + loff_t userspace_addr_offset; > + struct vm_area_struct *vma; > + bool ret = false; > + > + mmap_read_lock(mm); > + > + vma = vma_lookup(mm, slot->userspace_addr); > + if (!vma) > + goto out; > + > + if (vma->vm_file != file) > + goto out; > + > + userspace_addr_offset = slot->userspace_addr - vma->vm_start; > + ret = userspace_addr_offset + (vma->vm_pgoff << PAGE_SHIFT) == offset; You'd probably have to iterate over the whole range (which might span multiple VMAs), but reading the discussion, I'm fine with dropping this patch for now. I think it's more important to document that thoroughly: what does it mean when we use GUEST_MEMFD_FLAG_SUPPORT_SHARED and then pass that fd in a memslot. Skimming over patch #15, I assume this is properly documented in there. -- Cheers, David / dhildenb