zfs: disable use of hardware crypto offload drivers

From openzfs-master e7adccf7f commit message:
  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.

Patch Author:	Mark Johnston <markj@freebsd.org>

Obtained from:	openzfs/zfs@e7adccf7f537a4d07281a2b74b360154bae367bc
PR:		252981, 253595
MFS after:	3 days

(direct commit)

1 files changed, 13 insertions, 2 deletions

diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/crypto_os.c b/sys/contrib/openzfs/module/os/freebsd/zfs/crypto_os.c
index b86ffc59a21d..0a7241699842 100644
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/crypto_os.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/crypto_os.c
@@ -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++;