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FreeBSD: disable the use of hardware crypto offload drivers for now

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First, the crypto request completion handler contains a bug in that it
fails to reset fs_done correctly after the request is completed.  This
is only a problem for asynchronous drivers.  Second, some hardware
drivers have input constraints which ZFS does not satisfy.  For
instance, ccp(4) apparently requires the AAD length for AES-GCM to be a
multiple of the cipher block size, and with qat(4) the AES-GCM AAD
length may not be longer than 240 bytes.  FreeBSD's generic crypto
framework doesn't have a mechanism to automatically fall back to a
software implementation if a hardware driver cannot process a request,
and ZFS does not tolerate such errors.

The plan is to implement such a fallback mechanism, but with FreeBSD
13.0 approaching we should simply disable the use hardware drivers for
now.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Closes #11612
This commit is contained in:
Mark Johnston 2021-02-18 18:51:20 -05:00 committed by GitHub
parent 778869fa13
commit e7adccf7f5
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1 changed files with 13 additions and 2 deletions
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15
module/os/freebsd/zfs/crypto_os.c
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@ -293,8 +293,19 @@ freebsd_crypt_newsession(freebsd_crypt_session_t *sessp,
error = ENOTSUP;
goto bad;
}
error = crypto_newsession(&sessp->fs_sid, &csp,
CRYPTOCAP_F_HARDWARE | CRYPTOCAP_F_SOFTWARE);
/*
* Disable the use of hardware drivers on FreeBSD 13 and later since
* common crypto offload drivers impose constraints on AES-GCM AAD
* lengths that make them unusable for ZFS, and we currently do not have
* a mechanism to fall back to a software driver for requests not
* handled by a hardware driver.
*
* On 12 we continue to permit the use of hardware drivers since
* CPU-accelerated drivers such as aesni(4) register themselves as
* hardware drivers.
*/
error = crypto_newsession(&sessp->fs_sid, &csp, CRYPTOCAP_F_SOFTWARE);
mtx_init(&sessp->fs_lock, "FreeBSD Cryptographic Session Lock",
NULL, MTX_DEF);
crypt_sessions++;