linux-kernel - Re: [PATCH v11 7/8] pkcs7, x509: Add RSASSA-PSS support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2719442.1767873207@warthog.procyon.org.uk>
Date: Thu, 08 Jan 2026 11:53:27 +0000
From: David Howells <dhowells@...hat.com>
To: Ignat Korchagin <ignat@...udflare.com>
Cc: dhowells@...hat.com, Lukas Wunner <lukas@...ner.de>,
    Jarkko Sakkinen <jarkko@...nel.org>,
    Herbert Xu <herbert@...dor.apana.org.au>,
    Eric Biggers <ebiggers@...nel.org>,
    Luis Chamberlain <mcgrof@...nel.org>,
    Petr Pavlu <petr.pavlu@...e.com>, Daniel Gomez <da.gomez@...nel.org>,
    Sami Tolvanen <samitolvanen@...gle.com>,
    "Jason A . Donenfeld" <Jason@...c4.com>,
    Ard Biesheuvel <ardb@...nel.org>,
    Stephan Mueller <smueller@...onox.de>, linux-crypto@...r.kernel.org,
    keyrings@...r.kernel.org, linux-modules@...r.kernel.org,
    linux-kernel@...r.kernel.org
Subject: Re: [PATCH v11 7/8] pkcs7, x509: Add RSASSA-PSS support

Ignat Korchagin <ignat@...udflare.com> wrote:

> > +       case OID_id_rsassa_pss:
> > +               goto rsassa_pss;
> ...
> > +rsassa_pss:
> > +       if (!ctx->algo_params || !ctx->algo_params_size) {
> > +               pr_debug("RSASSA-PSS sig algo without parameters\n");
> > +               return -EBADMSG;
> > +       }
> > +
> > +       err = rsassa_parse_sig_params(sig, ctx->algo_params, ctx->algo_params_size);
> > +       if (err < 0)
> > +               return err;
> > +
> > +       sig->pkey_algo = "rsa";
> > +       sig->encoding = "emsa-pss";
> > +       goto out;
> >  }
> 
> I really don't like this. Is it possible to factor this out to a
> separate function and just call here? Should the factored function
> even be part of the implementation somehow?

I'll move the check into rsassa_parse_sig_params() and then move the remaining
code back into the switch case.  That also means that x509_note_sig_algo()
doesn't need the check either.  It does change the pr_fmt value seen by the
pr_debug(), but that's probably fine.

> >         ctx->last_oid = look_up_OID(value, vlen);
> >         if (ctx->last_oid == OID__NR) {
> > -               char buffer[50];
> > +               char buffer[56];
> >                 sprint_oid(value, vlen, buffer, sizeof(buffer));
> 
> I've seen this elsewhere in the crypto code (namely in ECC) but is it
> generally a good idea to declare long buffers on the stack?

It's not all that long (7 words on a 64-bit machine - similarish to a function
call), and the output of sprint_oid() is limited to it.

David