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[199.106.103.254]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-142e0d38207sm25010026c88.5.2026.08.30.23.21.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 30 Aug 2026 23:21:58 -0700 (PDT) Message-ID: Date: Mon, 31 Aug 2026 14:21:50 +0800 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 00/11] FBE virtualization: inline encryption for virtio-blk guests From: Linlin Zhang To: Eric Biggers Cc: axboe@kernel.dk, mst@redhat.com, jasowangio@gmail.com, James.Bottomley@hansenpartnership.com, martin.petersen@oracle.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, linux-block@vger.kernel.org, linux-crypto@vger.kernel.org, linux-scsi@vger.kernel.org, virtualization@lists.linux.dev, devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org, neeraj.soni@oss.qualcomm.com, gaurav.kashyap@oss.qualcomm.com, mani@kernel.org, andersson@kernel.org, konradybcio@kernel.org, bvanassche@acm.org, alim.akhtar@samsung.com, avri.altman@sandisk.com, stefanha@redhat.com, pbonzini@redhat.com, eperezma@redhat.com, xuanzhuo@linux.alibaba.com, linux-kernel@vger.kernel.org References: <20260827160806.1295313-1-linlin.zhang@oss.qualcomm.com> <20260827184219.GB2137493@google.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-ORIG-GUID: gYA5XisfNqNCpwhGXLtyf5fghmGHkuvS X-Proofpoint-GUID: gYA5XisfNqNCpwhGXLtyf5fghmGHkuvS X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODMxMDA1MyBTYWx0ZWRfX7Uy7KZlAOT7s JMWhgBRy6tX0ENO2XGxj2B2Qz9eAlnyBjt5QndN7SaAgn1dWduaKlxIZ7Zb+/sCFra6zpsG+Twi mMkRIFRHfF2C8J3yb8xuqqR72V0CaVlau5xSoXQ0sL0VUOHr6WQ7mXbhuGY1hlSjDKmg/7XYCUu Mm/bkSC+zx41ZkVWf/0ccH+OsYiHCDfS49jUpHQqhqTNtN8v9zUUkKMmTE1ditxZHHLtsHRcsFq +L0anLnUNKdpaIJ3rYOsHr6G/4/QQLP7TBT+KkSvgT9xwLEMbGAU5vpnYeUdXvX2Gon3py0KVvu FdAl5RWmoUrXqBhk/GCS7lnnzktw6vmfGODEo6Yy0ksryhhHKiBu2muV4qSmogHI66Se7Aq3GKz //9Qq7Fp3EPK1JLkIQ5gfjqAEHPL7yONLbgTTbgnudxxt6uuJUxDLNxsc+yTIHxvmua0D/vZVb2 L4tFt5eWZ7izWcABGKQ== X-Authority-Analysis: v=2.4 cv=S8/pBosP c=1 sm=1 tr=0 ts=6a951d88 cx=c_pps a=vVfyC5vLCtgYJKYeQD43oA==:117 a=JYp8KDb2vCoCEuGobkYCKw==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yx91gb_oNiZeI1HMLzn7:22 a=EUspDBNiAAAA:8 a=_h6NAR8LnRz2utxSRfIA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=rl5im9kqc5Lf4LNbBjHf:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwODMxMDA1MyBTYWx0ZWRfX6CZ8/KUQwlt1 QYtmaLBboImjLV1KsqbgLGYE6kEqfYonXnd3IXLfQGhBgiqxdd20w1KRIeaYp7R/HjUVXZL6B4l z73HesbrEJLhG7cCHgqQAdbx1smpdM0= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-31_02,2026-08-27_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 bulkscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608310053 On 8/28/2026 11:37 PM, Linlin Zhang wrote: > > > On 8/28/2026 2:42 AM, Eric Biggers wrote: >> On Thu, Aug 27, 2026 at 09:07:09AM -0700, Linlin Zhang wrote: >>> From: linlzhan >>> >>> Current virtio-blk does not provide a mechanism for a guest to >>> program hardware keys or submit encrypted I/O using pre-programmed >>> keyslots. It drops the crypto context when issuing a bio request >>> to the virtio-blk queue, preventing inline-encryption-based FBE >>> on virtio block devices. >>> >>> This series enables File-Based Encryption in guest VMs on Qualcomm >>> GVM platforms where the ICE inline encryption hardware is shared >>> between the host and guests. In this environment the guest kernel >>> has no access to the ICE hardware directly; it supplies a virtual >>> keyslot index and data unit number with each encrypted I/O request >>> via VIRTIO_BLK_F_INLINE_ENCRYPTION, and the host must translate the >>> virtual slot to a physical ICE keyslot and submit the bio — without >>> transferring raw key material across the VM boundary. >> >> This seems to be designed incorrectly by not making virtio-blk itself >> support key programming and eviction. That complicates things >> significantly by then having to handle the key programming and eviction >> out-of-band using Qualcomm-specific SCM calls. It also means that >> adding other implementations of this would be very difficult. >> >> There are some claims that not transmitting keys across the VM boundary >> is desirable. But that doesn't seem meaningful, given that all the I/O >> is transmitted across that boundary in plaintext anyway, and also it >> seems that hardware-wrapped keys will be supported too. >> >> Please make virtio-blk support the key programming, eviction, and >> HW-wrapped key management operations that are needed for this to work. >> >> - Eric > > Thanks for your comments! > > Not making virtio-blk itself support key programming and eviction is > something done deliberately. Based on that HW-wrapped key management > operations are also handled in the out-of-band path. > > There are bellow 2 approaches I investigated to let virtio-blk programming > the key. > > 1. virtio_blk implements blk_crypto_ll_ops interfaces, including program > key and evict key interfaces.(Same to 'the virtio-blk interface standardized > blk_crypto_ll_ops requests' mentioned by Stefan in the virtio SPEC thread) > > The guest's block crypto profile manages the keyslot in virtual slot > format in this scenario. > > - block crypto key and virt_slot index it passed to the hypervisor's > (EL2) device emulation (QEMU, using QEMU in the following) which > runs in userspace of the host. Besides of transferring the virtual > slot to the physical slot, a programming block crypto key UAPI need > be added. Follow current blk-crypto design, it may be like > BLKCRYPTOGENERATEKEY. I thought this results in a security risk that > allows userspace process a key into a key slot. > > - For key eviction, it's similar to above key programming handling, also > need a key eviction in blk IOCTLs, but leads to the security risk > that allow userspace client to evict a key in a key slot. > > virt_slot, DUN and DUSize is appended to virtblk request during crypto > I/O. > > 2. virtio_blk implements blk_crypto_ll_ops interfaces, excluding program > key and evict key interfaces. > > The guest's block crypto profile doesn't manage keyslot for the guest, > the host's block crypto profile manages keyslot for both the guest and > the host. The trigger of key programming operation is moved from the > guest to the host. > > - The whole block crypto key (key size, key bytes, blk_crypto_config) > and DUN are appended to the virtblk request during IO, a little > high payload. > > The backend parses the crypto message in the virtio queue and > construct a block crypto key and DUN for the bio_crypto_ctx > set to the BIO. So that the IO flow in the host can program > the key. > > The question is that the blk-crypto-profile distinguishs the > block crypto key via the key's address. But the host has > different key addresses for the programming and eviction key > operations of the same block crypto key from GVM, because the > key is re-constructed in the host for the key program and > eviction operations. > > To fix it, the approach I thought is maintaining a new key > hash table in the backend, and comparing the block crypto key > content and DUN parsed from virtio queue with that in the key > hash table. > My major concern is that this need keep the keys synchronization > b/w this new hash table and the blk-crypto-profile's hash table > carefully, avoiding that key is still present in the > blk-crypto-profile's hash table, but removed in backend hash > table. Another point is that the whole block crypto key and > DUN are appended into virtio block request per crypto I/O. > > - For key eviction, adding a key eviction in blk IOCTLs allows > userspace client to evict a key in a key slot. I thought this > is a security concern. Correction. The key eviction operation is also moved from the Guest's blk_crypto_profile to the Host's blk_crypto_profile. As a result, the entire block crypto key (including the key size, key material, and blk_crypto_config) is appended to the virtblk request. The backend parses the supplied blk_crypto_key, looks it up in its key hash table, and can then invoke blk_crypto_evict_key() to evict the corresponding key from the ICE keyslot. Unlike Approach 1, Approach 2 does not allow the guest to specify the keyslot to be evicted through the block ioctl interface. I'm appreciated if you can share your insights and thoughts about these 3 approaches. > > > This option doesn't need map virt_slot to physical one. > > > Taking all the above into account, I made a compromise to implement > blk_crypto_ll_ops interfaces in a out-of-band path, which lets the virtio > blk only need focus on the data path. I agree that it is complex than > the second option mentioned in the above, but small payload (only > virt_slot, DUN, DUSize) in the virtio block request and no security > risk of key eviction from userspace. > > > I would like to hear your thoughts about the above and am appreciated > if you could share your insights about the design of inline > encryption in virtio block. > > Regards, > Linlin > > >