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  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]
Date:   Tue, 8 Dec 2020 15:04:05 +0100
From:   Ard Biesheuvel <>
To:     David Howells <>
Cc:     Chuck Lever <>,
        Bruce Fields <>,
        CIFS <>,
        Linux NFS Mailing List <>,
        Herbert Xu <>,
        "open list:BPF JIT for MIPS (32-BIT AND 64-BIT)" 
        Linux Kernel Mailing List <>,
        Trond Myklebust <>,
        Linux Crypto Mailing List <>,,
Subject: Re: Why the auxiliary cipher in gss_krb5_crypto.c?

On Tue, 8 Dec 2020 at 14:25, David Howells <> wrote:
> I wonder - would it make sense to reserve two arrays of scatterlist structs
> and a mutex per CPU sufficient to map up to 1MiB of pages with each array
> while the krb5 service is in use?
> That way sunrpc could, say, grab the mutex, map the input and output buffers,
> do the entire crypto op in one go and then release the mutex - at least for
> big ops, small ops needn't use this service.
> For rxrpc/afs's use case this would probably be overkill - it's doing crypto
> on each packet, not on whole operations - but I could still make use of it
> there.
> However, that then limits the maximum size of an op to 1MiB, plus dangly bits
> on either side (which can be managed with chained scatterlist structs) and
> also limits the number of large simultaneous krb5 crypto ops we can do.

Apparently, it is permitted for gss_krb5_cts_crypt() to do a
kmalloc(GFP_NOFS) in the context from where gss_krb5_aes_encrypt() is
being invoked, and so I don't see why it wouldn't be possible to
simply kmalloc() a scatterlist[] of the appropriate size, populate it
with all the pages, bufs and whatever else gets passed into the
skcipher, and pass it into the skcipher in one go.

Powered by blists - more mailing lists