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SMB2: Separate Kerberos authentication from SMB2_sess_setup
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Add helper functions and split Kerberos authentication off
SMB2_sess_setup.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
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@spuiuk @smfrench
spuiuk authored and smfrench committed Oct 14, 2016
1 parent cb978ac commit 3baf1a7
Showing 1 changed file with 230 additions and 46 deletions.
276 changes: 230 additions & 46 deletions fs/cifs/smb2pdu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -593,6 +593,216 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon)
return -EIO;
}

struct SMB2_sess_data {
unsigned int xid;
struct cifs_ses *ses;
struct nls_table *nls_cp;
void (*func)(struct SMB2_sess_data *);
int result;
u64 previous_session;

/* we will send the SMB in three pieces:
* a fixed length beginning part, an optional
* SPNEGO blob (which can be zero length), and a
* last part which will include the strings
* and rest of bcc area. This allows us to avoid
* a large buffer 17K allocation
*/
int buf0_type;
struct kvec iov[2];
};

static int
SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
{
int rc;
struct cifs_ses *ses = sess_data->ses;
struct smb2_sess_setup_req *req;
struct TCP_Server_Info *server = ses->server;

rc = small_smb2_init(SMB2_SESSION_SETUP, NULL, (void **) &req);
if (rc)
return rc;

req->hdr.SessionId = 0; /* First session, not a reauthenticate */

/* if reconnect, we need to send previous sess id, otherwise it is 0 */
req->PreviousSessionId = sess_data->previous_session;

req->Flags = 0; /* MBZ */
/* to enable echos and oplocks */
req->hdr.CreditRequest = cpu_to_le16(3);

/* only one of SMB2 signing flags may be set in SMB2 request */
if (server->sign)
req->SecurityMode = SMB2_NEGOTIATE_SIGNING_REQUIRED;
else if (global_secflags & CIFSSEC_MAY_SIGN) /* one flag unlike MUST_ */
req->SecurityMode = SMB2_NEGOTIATE_SIGNING_ENABLED;
else
req->SecurityMode = 0;

req->Capabilities = 0;
req->Channel = 0; /* MBZ */

sess_data->iov[0].iov_base = (char *)req;
/* 4 for rfc1002 length field and 1 for pad */
sess_data->iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;
/*
* This variable will be used to clear the buffer
* allocated above in case of any error in the calling function.
*/
sess_data->buf0_type = CIFS_SMALL_BUFFER;

return 0;
}

static void
SMB2_sess_free_buffer(struct SMB2_sess_data *sess_data)
{
free_rsp_buf(sess_data->buf0_type, sess_data->iov[0].iov_base);
sess_data->buf0_type = CIFS_NO_BUFFER;
}

static int
SMB2_sess_sendreceive(struct SMB2_sess_data *sess_data)
{
int rc;
struct smb2_sess_setup_req *req = sess_data->iov[0].iov_base;

/* Testing shows that buffer offset must be at location of Buffer[0] */
req->SecurityBufferOffset =
cpu_to_le16(sizeof(struct smb2_sess_setup_req) -
1 /* pad */ - 4 /* rfc1001 len */);
req->SecurityBufferLength = cpu_to_le16(sess_data->iov[1].iov_len);

inc_rfc1001_len(req, sess_data->iov[1].iov_len - 1 /* pad */);

/* BB add code to build os and lm fields */

rc = SendReceive2(sess_data->xid, sess_data->ses,
sess_data->iov, 2,
&sess_data->buf0_type,
CIFS_LOG_ERROR | CIFS_NEG_OP);

return rc;
}

static int
SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
{
int rc = 0;
struct cifs_ses *ses = sess_data->ses;

mutex_lock(&ses->server->srv_mutex);
if (ses->server->sign && ses->server->ops->generate_signingkey) {
rc = ses->server->ops->generate_signingkey(ses);
kfree(ses->auth_key.response);
ses->auth_key.response = NULL;
if (rc) {
cifs_dbg(FYI,
"SMB3 session key generation failed\n");
mutex_unlock(&ses->server->srv_mutex);
goto keygen_exit;
}
}
if (!ses->server->session_estab) {
ses->server->sequence_number = 0x2;
ses->server->session_estab = true;
}
mutex_unlock(&ses->server->srv_mutex);

cifs_dbg(FYI, "SMB2/3 session established successfully\n");
spin_lock(&GlobalMid_Lock);
ses->status = CifsGood;
ses->need_reconnect = false;
spin_unlock(&GlobalMid_Lock);

keygen_exit:
if (!ses->server->sign) {
kfree(ses->auth_key.response);
ses->auth_key.response = NULL;
}
return rc;
}

#ifdef CONFIG_CIFS_UPCALL
static void
SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
{
int rc;
struct cifs_ses *ses = sess_data->ses;
struct cifs_spnego_msg *msg;
struct key *spnego_key = NULL;
struct smb2_sess_setup_rsp *rsp = NULL;

rc = SMB2_sess_alloc_buffer(sess_data);
if (rc)
goto out;

spnego_key = cifs_get_spnego_key(ses);
if (IS_ERR(spnego_key)) {
rc = PTR_ERR(spnego_key);
spnego_key = NULL;
goto out;
}

msg = spnego_key->payload.data[0];
/*
* check version field to make sure that cifs.upcall is
* sending us a response in an expected form
*/
if (msg->version != CIFS_SPNEGO_UPCALL_VERSION) {
cifs_dbg(VFS,
"bad cifs.upcall version. Expected %d got %d",
CIFS_SPNEGO_UPCALL_VERSION, msg->version);
rc = -EKEYREJECTED;
goto out_put_spnego_key;
}

ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
GFP_KERNEL);
if (!ses->auth_key.response) {
cifs_dbg(VFS,
"Kerberos can't allocate (%u bytes) memory",
msg->sesskey_len);
rc = -ENOMEM;
goto out_put_spnego_key;
}
ses->auth_key.len = msg->sesskey_len;

sess_data->iov[1].iov_base = msg->data + msg->sesskey_len;
sess_data->iov[1].iov_len = msg->secblob_len;

rc = SMB2_sess_sendreceive(sess_data);
if (rc)
goto out_put_spnego_key;

rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
ses->Suid = rsp->hdr.SessionId;

ses->session_flags = le16_to_cpu(rsp->SessionFlags);
if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
cifs_dbg(VFS, "SMB3 encryption not supported yet\n");

rc = SMB2_sess_establish_session(sess_data);
out_put_spnego_key:
key_invalidate(spnego_key);
key_put(spnego_key);
out:
sess_data->result = rc;
sess_data->func = NULL;
SMB2_sess_free_buffer(sess_data);
}
#else
static void
SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
{
cifs_dbg(VFS, "Kerberos negotiated but upcall support disabled!\n");
sess_data->result = -EOPNOTSUPP;
sess_data->func = NULL;
}
#endif

int
SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
const struct nls_table *nls_cp)
Expand All @@ -605,11 +815,11 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
__le32 phase = NtLmNegotiate; /* NTLMSSP, if needed, is multistage */
struct TCP_Server_Info *server = ses->server;
u16 blob_length = 0;
struct key *spnego_key = NULL;
char *security_blob = NULL;
unsigned char *ntlmssp_blob = NULL;
bool use_spnego = false; /* else use raw ntlmssp */
u64 previous_session = ses->Suid;
struct SMB2_sess_data *sess_data;

cifs_dbg(FYI, "Session Setup\n");

Expand All @@ -618,6 +828,20 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
return -EIO;
}

sess_data = kzalloc(sizeof(struct SMB2_sess_data), GFP_KERNEL);
if (!sess_data)
return -ENOMEM;
sess_data->xid = xid;
sess_data->ses = ses;
sess_data->buf0_type = CIFS_NO_BUFFER;
sess_data->nls_cp = (struct nls_table *) nls_cp;
sess_data->previous_session = ses->Suid;

if (ses->sectype == Kerberos) {
SMB2_auth_kerberos(sess_data);
goto out;
}

/*
* If we are here due to reconnect, free per-smb session key
* in case signing was required.
Expand Down Expand Up @@ -670,47 +894,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
/* 4 for rfc1002 length field and 1 for pad */
iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;

if (ses->sectype == Kerberos) {
#ifdef CONFIG_CIFS_UPCALL
struct cifs_spnego_msg *msg;

spnego_key = cifs_get_spnego_key(ses);
if (IS_ERR(spnego_key)) {
rc = PTR_ERR(spnego_key);
spnego_key = NULL;
goto ssetup_exit;
}

msg = spnego_key->payload.data[0];
/*
* check version field to make sure that cifs.upcall is
* sending us a response in an expected form
*/
if (msg->version != CIFS_SPNEGO_UPCALL_VERSION) {
cifs_dbg(VFS,
"bad cifs.upcall version. Expected %d got %d",
CIFS_SPNEGO_UPCALL_VERSION, msg->version);
rc = -EKEYREJECTED;
goto ssetup_exit;
}
ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
GFP_KERNEL);
if (!ses->auth_key.response) {
cifs_dbg(VFS,
"Kerberos can't allocate (%u bytes) memory",
msg->sesskey_len);
rc = -ENOMEM;
goto ssetup_exit;
}
ses->auth_key.len = msg->sesskey_len;
blob_length = msg->secblob_len;
iov[1].iov_base = msg->data + msg->sesskey_len;
iov[1].iov_len = blob_length;
#else
rc = -EOPNOTSUPP;
goto ssetup_exit;
#endif /* CONFIG_CIFS_UPCALL */
} else if (phase == NtLmNegotiate) { /* if not krb5 must be ntlmssp */
if (phase == NtLmNegotiate) {
ntlmssp_blob = kmalloc(sizeof(struct _NEGOTIATE_MESSAGE),
GFP_KERNEL);
if (ntlmssp_blob == NULL) {
Expand Down Expand Up @@ -853,12 +1037,12 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
kfree(ses->auth_key.response);
ses->auth_key.response = NULL;
}
if (spnego_key) {
key_invalidate(spnego_key);
key_put(spnego_key);
}
kfree(ses->ntlmssp);

return rc;
out:
rc = sess_data->result;
kfree(sess_data);
return rc;
}

Expand Down

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