On Wed, Sep 8, 2010 at 12:25 PM, Jeff Layton <jlayton@xxxxxxxxxxxxxxx> wrote:
> On Wed, 8 Sep 2010 12:04:38 -0500
> shirishpargaonkar@xxxxxxxxx wrote:
>
>> From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
>>
>>
>> A key is exchanged with the server if client indicates so in flags in
>> type 1 messsage and server agrees in flag in type 2 message of ntlmssp
>> negotiation. If both client and agree, a key sent by client in
>> type 3 message of ntlmssp negotiation in the session key field.
>> The key is a ciphertext generated off of secondary key, a nonce, using
>> ntlmv2 hash via rc4/arc4. ciphertext is calculated within a mutex lock.
>>
>> If authentication is successful, the secondary key is the that client
>> uses to calculate cifs/smb signature in the messages that client sends
>> and to verify the messages sent by server.
>> This key stays with the smb connection for its life and is the key used
>> to generate (and verify) signatures for all the subsequent smb sessions
>> for this smb connection.
>>
>> So only for the first smb session on any smb connection, type 1 message
>> of ntlmssp negotiation selects the flag NTLMSSP_NEGOTIATE_KEY_XCH.
>> It is not used for subsequent smb sessions on this smb connection i.e.
>> no need to generate secondary key, create ciphertext and send it etc.
>>
>> After the very first successful smb session, sequence number gets set
>> to 0 and variable cphready is used to mark that the key calculations
>> are done, this is done within a mutex lock.
>>
>>
>> Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
>> ---
>> fs/cifs/cifsencrypt.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++
>> fs/cifs/cifsproto.h | 1 +
>> fs/cifs/connect.c | 1 +
>> fs/cifs/sess.c | 24 +++++++++++++++++-----
>> 4 files changed, 72 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
>> index f9c140a..197fc85 100644
>> --- a/fs/cifs/cifsencrypt.c
>> +++ b/fs/cifs/cifsencrypt.c
>> @@ -470,6 +470,58 @@ void CalcNTLMv2_response(const struct cifsSesInfo *ses,
>> /* cifs_dump_mem("v2_sess_rsp: ", v2_session_response, 32); */
>> }
>>
>> +int
>> +calc_seckey(struct TCP_Server_Info *server)
>> +{
>> + int rc;
>> + struct crypto_blkcipher *tfm_arc4;
>> + struct scatterlist sgin, sgout;
>> + struct blkcipher_desc desc;
>> +
>> + if (!server) {
>> + cERROR(1, "%s: Can't determine ciphertext key\n", __func__);
>> + return 1;
>> + }
>> +
>> + mutex_lock(&server->srv_mutex);
>> + if (server->cphready) {
>> + mutex_unlock(&server->srv_mutex);
>> + return 0;
>> + }
>> +
>> + get_random_bytes(server->ntlmssp.sec_key, CIFS_NTLMV2_SESSKEY_SIZE);
>> +
>> + tfm_arc4 = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
>> + if (!tfm_arc4 || IS_ERR(tfm_arc4)) {
>> + cERROR(1, "could not allocate arc4 crypto function\n");
>> + mutex_unlock(&server->srv_mutex);
>> + return 1;
>> + }
>> +
>> + desc.tfm = tfm_arc4;
>> +
>> + crypto_blkcipher_setkey(tfm_arc4, server->session_key.data.ntlmv2.key,
>> + CIFS_CPHTXT_SIZE);
>> +
>> + sg_init_one(&sgin, server->ntlmssp.sec_key, CIFS_CPHTXT_SIZE);
>> + sg_init_one(&sgout, server->ntlmssp.ciphertext, CIFS_CPHTXT_SIZE);
>> +
>> + rc = crypto_blkcipher_encrypt(&desc, &sgout, &sgin, CIFS_CPHTXT_SIZE);
>> + if (rc) {
>> + cERROR(1, "could not encrypt session key rc: %d\n", rc);
>> + mutex_unlock(&server->srv_mutex);
>> + return rc;
>> + }
>> +
>> + crypto_free_blkcipher(tfm_arc4);
>> +
>> + server->sequence_number = 0;
>> + server->cphready = true;
>> + mutex_unlock(&server->srv_mutex);
>> +
>> + return 0;
>> +}
>> +
>> void
>> cifs_crypto_shash_release(struct TCP_Server_Info *server)
>> {
>> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
>> index fbfdd8e..b78bb77 100644
>> --- a/fs/cifs/cifsproto.h
>> +++ b/fs/cifs/cifsproto.h
>> @@ -370,6 +370,7 @@ extern int setup_ntlmv2_rsp(struct cifsSesInfo *, char *,
>> const struct nls_table *);
>> extern int cifs_crypto_shash_allocate(struct TCP_Server_Info *);
>> extern void cifs_crypto_shash_release(struct TCP_Server_Info *);
>> +extern int calc_seckey(struct TCP_Server_Info *);
>> #ifdef CONFIG_CIFS_WEAK_PW_HASH
>> extern void calc_lanman_hash(const char *password, const char *cryptkey,
>> bool encrypt, char *lnm_session_key);
>> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
>> index 0621a72..e3883f3 100644
>> --- a/fs/cifs/connect.c
>> +++ b/fs/cifs/connect.c
>> @@ -1587,6 +1587,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
>> goto out_err2;
>> }
>>
>> + tcp_ses->cphready = false;
>
> I see that you're setting this when you spawn a new tcp session. What
> about reconnects though? Don't you also need to set this to false when
> the socket needs to be reconnected?
>
>> tcp_ses->noblocksnd = volume_info->noblocksnd;
>> tcp_ses->noautotune = volume_info->noautotune;
>> tcp_ses->tcp_nodelay = volume_info->sockopt_tcp_nodelay;
>> diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
>> index 68ea153..7c94d7b 100644
>> --- a/fs/cifs/sess.c
>> +++ b/fs/cifs/sess.c
>> @@ -444,10 +444,12 @@ static void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
>> NTLMSSP_NEGOTIATE_128 | NTLMSSP_NEGOTIATE_UNICODE |
>> NTLMSSP_NEGOTIATE_NTLM;
>> if (ses->server->secMode &
>> - (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED))
>> + (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
>> flags |= NTLMSSP_NEGOTIATE_SIGN;
>> - if (ses->server->secMode & SECMODE_SIGN_REQUIRED)
>> - flags |= NTLMSSP_NEGOTIATE_ALWAYS_SIGN;
>> + if (!ses->server->cphready)
>> + flags |= NTLMSSP_NEGOTIATE_KEY_XCH |
>> + NTLMSSP_NEGOTIATE_EXTENDED_SEC;
>> + }
>>
>> sec_blob->NegotiateFlags |= cpu_to_le32(flags);
>>
>> @@ -554,9 +556,19 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer,
>> sec_blob->WorkstationName.MaximumLength = 0;
>> tmp += 2;
>>
>> - sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer);
>> - sec_blob->SessionKey.Length = 0;
>> - sec_blob->SessionKey.MaximumLength = 0;
>> + if ((ses->server->ntlmssp.server_flags & NTLMSSP_NEGOTIATE_KEY_XCH) &&
>> + !calc_seckey(ses->server)) {
>> + memcpy(tmp, ses->server->ntlmssp.ciphertext, CIFS_CPHTXT_SIZE);
>> + sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer);
>> + sec_blob->SessionKey.Length = cpu_to_le16(CIFS_CPHTXT_SIZE);
>> + sec_blob->SessionKey.MaximumLength =
>> + cpu_to_le16(CIFS_CPHTXT_SIZE);
>> + tmp += CIFS_CPHTXT_SIZE;
>> + } else {
>> + sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer);
>> + sec_blob->SessionKey.Length = 0;
>> + sec_blob->SessionKey.MaximumLength = 0;
>> + }
>>
>> setup_ntlmv2_ret:
>> return tmp - pbuffer;
>
>
> --
> Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
> --
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>
Jeff, yes. I think this patch should take care of that
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index e3883f3..aa40f1a 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -199,6 +199,7 @@ cifs_reconnect(struct TCP_Server_Info *server)
if (server->tcpStatus != CifsExiting)
server->tcpStatus = CifsGood;
server->sequence_number = 0;
+ server->cphready = false;
spin_unlock(&GlobalMid_Lock);
/* atomic_set(&server->inFlight,0);*/
wake_up(&server->response_q);
I will respin this patch (7/8) again with that change in.
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