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From: David Howells <dhowells@redhat.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: dhowells@redhat.com, Chuck Lever <chuck.lever@oracle.com>,
	Bruce Fields <bfields@fieldses.org>,
	CIFS <linux-cifs@vger.kernel.org>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"open list:BPF JIT for MIPS (32-BIT AND 64-BIT)" 
	<netdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Trond Myklebust <trond.myklebust@hammerspace.com>,
	Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org
Subject: Re: Why the auxiliary cipher in gss_krb5_crypto.c?
Date: Tue, 08 Dec 2020 14:13:48 +0000	[thread overview]
Message-ID: <960649.1607436828@warthog.procyon.org.uk> (raw)
In-Reply-To: <CAMj1kXE+oi2Q7OE8o0xP4XabZt-y61NMG3Q3eyRzSG6cG9i4Kg@mail.gmail.com>

Ard Biesheuvel <ardb@kernel.org> wrote:

> 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.

I never said it wasn't possible.  But doing a pair of order-1 allocations from
there might have a significant detrimental effect on performance - in which
case Trond and co. will say "no".

Remember: to crypt 1MiB of data on a 64-bit machine requires 2 x minimum 8KiB
scatterlist arrays.  That's assuming the pages in the middle are contiguous,
which might not be the case for a direct I/O read/write.  So for the DIO case,
it could be involve an order-2 allocation (or chaining of single pages).

David


  parent reply	other threads:[~2020-12-08 14:15 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12 12:57 [RFC][PATCH 00/18] crypto: Add generic Kerberos library David Howells
2020-11-12 12:57 ` [PATCH 01/18] crypto/krb5: Implement Kerberos crypto core David Howells
2020-11-12 12:58 ` [PATCH 02/18] crypto/krb5: Add some constants out of sunrpc headers David Howells
2020-11-12 12:58 ` [PATCH 03/18] crypto/krb5: Provide infrastructure and key derivation David Howells
2020-11-12 12:58 ` [PATCH 04/18] crypto/krb5: Implement the Kerberos5 rfc3961 " David Howells
2020-11-12 12:58 ` [PATCH 05/18] crypto/krb5: Implement the Kerberos5 rfc3961 encrypt and decrypt functions David Howells
2020-11-12 12:58 ` [PATCH 06/18] crypto/krb5: Implement the Kerberos5 rfc3961 get_mic and verify_mic David Howells
2020-11-12 12:58 ` [PATCH 07/18] crypto/krb5: Implement the AES enctypes from rfc3962 David Howells
2020-11-12 12:58 ` [PATCH 08/18] crypto/krb5: Implement crypto self-testing David Howells
2020-11-12 12:58 ` [PATCH 09/18] crypto/krb5: Implement the AES enctypes from rfc8009 David Howells
2020-11-12 12:59 ` [PATCH 10/18] crypto/krb5: Implement the AES encrypt/decrypt " David Howells
2020-11-12 12:59 ` [PATCH 11/18] crypto/krb5: Add the AES self-testing data " David Howells
2020-11-12 12:59 ` [PATCH 12/18] crypto/krb5: Implement the Camellia enctypes from rfc6803 David Howells
2020-11-12 12:59 ` [PATCH 13/18] rxrpc: Add the security index for yfs-rxgk David Howells
2020-11-12 12:59 ` [PATCH 14/18] rxrpc: Add YFS RxGK (GSSAPI) security class David Howells
2020-11-12 12:59 ` [PATCH 15/18] rxrpc: rxgk: Provide infrastructure and key derivation David Howells
2020-11-12 12:59 ` [PATCH 16/18] rxrpc: rxgk: Implement the yfs-rxgk security class (GSSAPI) David Howells
2020-11-12 13:00 ` [PATCH 17/18] rxrpc: rxgk: Implement connection rekeying David Howells
2020-11-12 13:00 ` [PATCH 18/18] rxgk: Support OpenAFS's rxgk implementation David Howells
2020-11-12 13:44 ` [RFC][PATCH 00/18] crypto: Add generic Kerberos library David Howells
2020-11-12 14:36 ` Chuck Lever
2020-11-12 15:42 ` David Howells
2020-11-12 15:49   ` Chuck Lever
2020-11-12 16:54   ` David Howells
2020-11-12 21:07     ` Bruce Fields
2020-11-12 21:09       ` Chuck Lever
2020-11-12 18:37 ` J. Bruce Fields
2020-11-12 18:39   ` Chuck Lever
2020-11-26  6:33 ` Herbert Xu
2020-11-26  8:19 ` David Howells
2020-11-27  5:07   ` Herbert Xu
2020-12-01  8:44   ` David Howells
2020-12-01  8:46     ` Herbert Xu
2020-12-01  9:12     ` David Howells
2020-12-01 10:36       ` Herbert Xu
2020-12-04 14:59 ` Why the auxiliary cipher in gss_krb5_crypto.c? David Howells
2020-12-04 15:46   ` Bruce Fields
2020-12-04 16:05     ` Chuck Lever
2020-12-04 16:14     ` Bruce Fields
2020-12-04 16:01   ` David Howells
2020-12-04 16:03     ` Bruce Fields
2020-12-04 16:50     ` David Howells
2020-12-04 17:06       ` Ard Biesheuvel
2020-12-04 17:19       ` David Howells
2020-12-04 17:35         ` Ard Biesheuvel
2020-12-04 21:08           ` Herbert Xu
2020-12-07  8:24           ` David Howells
2020-12-07 12:01         ` David Howells
2020-12-07 13:08           ` Ard Biesheuvel
2020-12-07 14:15           ` David Howells
2020-12-08  8:27             ` Ard Biesheuvel
2020-12-08  9:18             ` David Howells
2020-12-04 18:13   ` Theodore Y. Ts'o
2020-12-08 13:25 ` David Howells
2020-12-08 14:04   ` Ard Biesheuvel
2020-12-08 14:13   ` David Howells [this message]
2020-12-08 14:02 ` David Howells

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