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Thu, 12 Mar 2026 23:29:05 +0000 (GMT) Message-ID: <1c5f16f0913bae48bf2f24feaaaf3525ecdf4c97.camel@linux.ibm.com> Subject: Re: [PATCH] ima: remove buggy support for asynchronous hashes From: Mimi Zohar To: Eric Biggers , linux-integrity@vger.kernel.org, Roberto Sassu , Dmitry Kasatkin Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20260312053933.53012-1-ebiggers@kernel.org> References: <20260312053933.53012-1-ebiggers@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Thu, 12 Mar 2026 19:29:05 -0400 Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: tuFJD93rQt2-ourjkBQZvSV0CRkMpYfG X-Authority-Analysis: v=2.4 cv=E6/AZKdl c=1 sm=1 tr=0 ts=69b34c44 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=M1lwNKzopv0IjOVRZAQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzEyMDE4NSBTYWx0ZWRfXwv2Jxp38834c gOCp/l5g3cTuTyuWT7i8kqx3LQYILKHyFC0PEHvLBGZzJWbmtqrXVqx4gKLvgUmfwb71gO1wfhx EnJnbDchfqVPWHxG/Aesx9wZXD1S3LaiBvk6f4xPHWK+2xgJO19J6rxDH6i3FfeULnzzdr8ZzXA 88AeuM8Wc36TOfItqmmqf3QxFK9G7X8VS5zaKeMc62CS+onk4MshdYiN9IuxxMXo+jbB9YFguWW sXEJaagm/6QOao4Xhh3FugvWpHungCIsFh8wF5I0SZk2t8kt4FTUBVtaWOTgAm1qDq/QaGCCpTw +YA89n6RmS5Be+Lz7bprBSj8cq9ZWN/F8iU9OqpbJ4L6HjWKf2SujsYkGWKUzIlR25My9vvWtJO 5zX33KmbEvdrdVl6qLSL555KxSJpIihjmWQ9XXudDhVog33bBCW0+7FzS2qETJprOnTxYe6ETRa xjChO4FrZj5OXdX5tOg== X-Proofpoint-ORIG-GUID: SQaYzt5GqpusUkQQv835gltrlGmbVQDs X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-12_03,2026-03-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 clxscore=1015 malwarescore=0 phishscore=0 suspectscore=0 priorityscore=1501 spamscore=0 lowpriorityscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603120185 On Wed, 2026-03-11 at 22:39 -0700, Eric Biggers wrote: > IMA computes hashes using the crypto_shash or crypto_ahash API.=C2=A0 The > latter is used only when ima.ahash_minsize is set on the command line, > and its purpose is ostensibly to make the hash computation faster. >=20 > However, going off the CPU to a crypto engine and back again is actually > quite slow, especially compared with the acceleration that is built into > modern CPUs and the kernel now enables by default for most algorithms. > Typical performance results for SHA-256 on a modern platform can be > found at https://lore.kernel.org/linux-crypto/20250615184638.GA1480@sol/ >=20 > Partly for this reason, several other kernel subsystems have already > dropped support for the crypto_ahash API. The performance benefit was the ability of reading and filling a buffer fro= m=20 disk, which was slow, while the other buffer was sent to the crypto engine. I'm all for removing extraneous code. I'll give it a couple of days, befor= e queuing the patch in case there are any objections. thanks, Mimi