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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 In-Reply-To: References: <20260121223609.1650735-1-dhowells@redhat.com> <20260121223609.1650735-4-dhowells@redhat.com> To: Jarkko Sakkinen Cc: dhowells@redhat.com, Lukas Wunner , Ignat Korchagin , Herbert Xu , Eric Biggers , Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , "Jason A . Donenfeld" , Ard Biesheuvel , Stephan Mueller , linux-crypto@vger.kernel.org, keyrings@vger.kernel.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v14 3/5] pkcs7: Allow the signing algo to do whatever digestion it wants itself Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1902787.1769425830.1@warthog.procyon.org.uk> From: David Howells Date: Mon, 26 Jan 2026 11:11:08 +0000 Message-ID: <1902869.1769425868@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Jarkko Sakkinen wrote: > > (1) Rename ->digest and ->digest_len to ->m and ->m_size to represent the > > input to the signature verification algorithm, reflecting that > > ->digest may no longer actually *be* a digest. > ... > These renames emit enough noise to be split into a separate patch. Yeah, I had considered that, so I've now done that. > > + if (sig->algo_takes_data) { > > + sig->m_size = sinfo->authattrs_len; > > + memcpy(sig->m, sinfo->authattrs, sinfo->authattrs_len); > > + sig->m[0] = ASN1_CONS_BIT | ASN1_SET; > > + ret = 0; > > + } else { > > + u8 tag = ASN1_CONS_BIT | ASN1_SET; > > + > > + ret = crypto_shash_init(desc); > > + if (ret < 0) > > + goto error; > > + ret = crypto_shash_update(desc, &tag, 1); > > + if (ret < 0) > > + goto error; > > + ret = crypto_shash_finup(desc, sinfo->authattrs + 1, > > + sinfo->authattrs_len - 1, > > + sig->m); > > + if (ret < 0) > > + goto error; > > + } Thinking further on this, I think it's better just to do the copy and modify unconditionally and then in the second case here just call crypto_hash_digest(). That means we end up doing a single crypto call on an aligned buffer. It's not like expect the authattrs to be particularly big for an RSA signature. David