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s3:smb2_negprot: prefer AES128_CCM if the client supports it

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Callgrind showed that we use 28,165,720,719 cpu cycles to send
a 100MB file to a client using aes-ccm.

With aes-gcm this is raises up to 723,094,413,831 cpu cycles.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11451

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
(cherry picked from commit bd0ec51cfca2b3baed60d304125079c74815073a)
This commit is contained in:
Stefan Metzmacher 2015-08-17 08:56:43 +02:00
parent ef11f8d267
commit 2aff77c172
1 changed files with 14 additions and 4 deletions

18
source3/smbd/smb2_negprot.c

@ -421,6 +421,8 @@ NTSTATUS smbd_smb2_request_process_negprot(struct smbd_smb2_request *req)
uint8_t buf[4];
DATA_BLOB b;
size_t i;
bool aes_128_ccm_supported = false;
bool aes_128_gcm_supported = false;
capabilities &= ~SMB2_CAP_ENCRYPTION;
@ -451,15 +453,23 @@ NTSTATUS smbd_smb2_request_process_negprot(struct smbd_smb2_request *req)
p += 2;
if (v == SMB2_ENCRYPTION_AES128_GCM) {
xconn->smb2.server.cipher = v;
break;
aes_128_gcm_supported = true;
}
if (v == SMB2_ENCRYPTION_AES128_CCM) {
xconn->smb2.server.cipher = v;
break;
aes_128_ccm_supported = true;
}
}
/*
* For now we preferr CCM because our implementation
* is faster than GCM, see bug #11451.
*/
if (aes_128_ccm_supported) {
xconn->smb2.server.cipher = SMB2_ENCRYPTION_AES128_CCM;
} else if (aes_128_gcm_supported) {
xconn->smb2.server.cipher = SMB2_ENCRYPTION_AES128_GCM;
}
SSVAL(buf, 0, 1); /* ChiperCount */
SSVAL(buf, 2, xconn->smb2.server.cipher);