From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9398727F747 for ; Wed, 14 May 2025 17:39:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747244371; cv=none; b=b+rbVcYmkkmH2UUV/IqcdB5BipJFa9QMO47IJxZboKlVgmvP1PCJ3ge2ovBhZNivR3dZwiBvcqA7jRf0ReYxoo449ODZ/QKbBIpVqw/fOVh/FRTu+1MBlaDsRLUuS6khxXvKcrQZYUIGPUAv7beKrSggOjb+x+E939pvb0gO+g0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747244371; c=relaxed/simple; bh=DybxN6tHW3pRqRDzexg5O/mxkhdrtfiw60WByyFkILo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=p7sLGKcp7wY+RFP8ckLb1/NFB+mFd7a2lsldeaLPucGSIfzZ79LBbK03qtPJ/5dD1kqNoG0d8lA6Nx7o+PT9uPno+UFT1wK2slLQVBH+HHgMGWymm8MD9Z/R6Gc4XjQnYSaOhYO6c/8dPhgIyns6wVZ3W+CBJBrU1W9kfuHnSv4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=U8+ok9Xj; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="U8+ok9Xj" 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-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-473-98Ge370hMXCP61zFZ0QKpw-1; Wed, 14 May 2025 13:39:27 -0400 X-MC-Unique: 98Ge370hMXCP61zFZ0QKpw-1 X-Mimecast-MFC-AGG-ID: 98Ge370hMXCP61zFZ0QKpw_1747244366 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-43cf44b66f7so434385e9.1 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=KaR+GImSe4BG+JzfP9+D1XMZq1MKBzRyGxAvQoIr4Shna2nYspnngQz46AUz0Ic5Qm 1BuGlGL5vMtPOGKK/r9Qi9AXZYu5PIMtsNx5O5H3tXU7QmnCsUm2L2QNrEAyKbRXG2s9 GmAUqhKORtuHh/dDtN8E+Avru7BrO2n64eStCPcaYiIV2mJl/dj0adAQ8MsuomNANPdC jLy/18Xr+Uk9xWVjQ4BKdPCFfUMqow/iWq/h/IUYPfah2qDhSx7fKrywFiEnFXRm84dv Tc9p2Pe+ZbvtxwZwlPcoHrH8q3+2n6o6Sk1EggLY+1HIlIF2NNPUpFuKXXszt9Ghz96U wCIg== X-Forwarded-Encrypted: i=1; AJvYcCVLEyAmtTK0ifQXUolCVWBw0LOZZsWXj7xnWvedFbZQAItvlpsVOfOMK736GShlgJKyQoM=@vger.kernel.org X-Gm-Message-State: AOJu0YzgHo4zJA6panZCVgIPUsH1ztpXdQZtcjfO9LejZSZBS3vTFa1p n5HTBTv0CUcLZXRelR1etvgxuPXGagpY61mcVigo49Sm29LD7wom0AKL94CrQa4UdNeqIsyADYa gAPtiSocNwXo0/Ab8yYkT/BW3eF93/0xz6pXmE7MhTjejF1ho2A== X-Gm-Gg: ASbGncvDm1B7iFiaN9YS6joxL1UuV/H/b+scWULwdLAzP8n0pZR51HbSPtts3ETYIGf wbG0OVziKokBgP4t0/nE8HUAxE/xUeUez8AoiC0vra/UgBE4eWi7H+bP0L/JsE9jcyXeSH16hiG RRkSfCegN69qvgr+OnpXB1+oGPxj5YbYc33ApPFWB3It81b3gNTYxeUcv6U3uOCQJlBJAM1jr9x PeV4F95GnRGodJFMBDgqBJR0YOp7lhtrO2C3Il0YSR4IxIxTHcL2gPBiK1GnX/+YrHZseNS3J1r SONKbOsDLvI0U32eMzHXrH6vobiX6rz7YybjlzDdOERQbKgtir/O88UnT4N4p5f7CYkL49+Ptqo QbEbNdW5OgcFjIroKcYwXuTqs6dKKBlXkxlRFS6g= X-Received: by 2002:a05:600c:358b:b0:43d:42b:e186 with SMTP id 5b1f17b1804b1-442f20e8141mr39825305e9.8.1747244365836; 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 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 Content-Language: en-US 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> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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