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NTLM auth and sign - Allocate session key/client response dynamically
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Start calculating auth response within a session.  Move/Add pertinet
data structures like session key, server challenge and ntlmv2_hash in
a session structure.  We should do the calculations within a session
before copying session key and response over to server data
structures because a session setup can fail.

Only after a very first smb session succeeds, it copy/make its
session key, session key of smb connection.  This key stays with
the smb connection throughout its life.
sequence_number within server is set to 0x2.

The authentication Message Authentication Key (mak) which consists
of session key followed by client response within structure session_key
is now dynamic.  Every authentication type allocates the key + response
sized memory within its session structure and later either assigns or
frees it once the client response is sent and if session's session key
becomes connetion's session key.

ntlm/ntlmi authentication functions are rearranged.  A function
named setup_ntlm_resp(), similar to setup_ntlmv2_resp(), replaces
function cifs_calculate_session_key().

size of CIFS_SESS_KEY_SIZE is changed to 16, to reflect the byte size
of the key it holds.

Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
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Shirish Pargaonkar authored and Steve French committed Oct 26, 2010
1 parent 6573e9b commit 21e7339
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Showing 7 changed files with 134 additions and 137 deletions.
113 changes: 65 additions & 48 deletions fs/cifs/cifsencrypt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,15 +43,16 @@ extern void SMBencrypt(unsigned char *passwd, const unsigned char *c8,
unsigned char *p24);

static int cifs_calculate_signature(const struct smb_hdr *cifs_pdu,
const struct session_key *key, char *signature)
struct TCP_Server_Info *server, char *signature)
{
struct MD5Context context;

if ((cifs_pdu == NULL) || (signature == NULL) || (key == NULL))
if (cifs_pdu == NULL || signature == NULL || server == NULL)
return -EINVAL;

cifs_MD5_init(&context);
cifs_MD5_update(&context, (char *)&key->data, key->len);
cifs_MD5_update(&context, server->session_key.response,
server->session_key.len);
cifs_MD5_update(&context, cifs_pdu->Protocol, cifs_pdu->smb_buf_length);

cifs_MD5_final(signature, &context);
Expand Down Expand Up @@ -79,8 +80,7 @@ int cifs_sign_smb(struct smb_hdr *cifs_pdu, struct TCP_Server_Info *server,
server->sequence_number++;
spin_unlock(&GlobalMid_Lock);

rc = cifs_calculate_signature(cifs_pdu, &server->session_key,
smb_signature);
rc = cifs_calculate_signature(cifs_pdu, server, smb_signature);
if (rc)
memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
else
Expand All @@ -90,16 +90,17 @@ int cifs_sign_smb(struct smb_hdr *cifs_pdu, struct TCP_Server_Info *server,
}

static int cifs_calc_signature2(const struct kvec *iov, int n_vec,
const struct session_key *key, char *signature)
struct TCP_Server_Info *server, char *signature)
{
struct MD5Context context;
int i;

if ((iov == NULL) || (signature == NULL) || (key == NULL))
if (iov == NULL || signature == NULL || server == NULL)
return -EINVAL;

cifs_MD5_init(&context);
cifs_MD5_update(&context, (char *)&key->data, key->len);
cifs_MD5_update(&context, server->session_key.response,
server->session_key.len);
for (i = 0; i < n_vec; i++) {
if (iov[i].iov_len == 0)
continue;
Expand Down Expand Up @@ -146,8 +147,7 @@ int cifs_sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
server->sequence_number++;
spin_unlock(&GlobalMid_Lock);

rc = cifs_calc_signature2(iov, n_vec, &server->session_key,
smb_signature);
rc = cifs_calc_signature2(iov, n_vec, server, smb_signature);
if (rc)
memset(cifs_pdu->Signature.SecuritySignature, 0, 8);
else
Expand All @@ -157,14 +157,14 @@ int cifs_sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *server,
}

int cifs_verify_signature(struct smb_hdr *cifs_pdu,
const struct session_key *session_key,
struct TCP_Server_Info *server,
__u32 expected_sequence_number)
{
unsigned int rc;
char server_response_sig[8];
char what_we_think_sig_should_be[20];

if (cifs_pdu == NULL || session_key == NULL)
if (cifs_pdu == NULL || server == NULL)
return -EINVAL;

if (cifs_pdu->Command == SMB_COM_NEGOTIATE)
Expand Down Expand Up @@ -193,7 +193,7 @@ int cifs_verify_signature(struct smb_hdr *cifs_pdu,
cpu_to_le32(expected_sequence_number);
cifs_pdu->Signature.Sequence.Reserved = 0;

rc = cifs_calculate_signature(cifs_pdu, session_key,
rc = cifs_calculate_signature(cifs_pdu, server,
what_we_think_sig_should_be);

if (rc)
Expand All @@ -209,18 +209,28 @@ int cifs_verify_signature(struct smb_hdr *cifs_pdu,

}

/* We fill in key by putting in 40 byte array which was allocated by caller */
int cifs_calculate_session_key(struct session_key *key, const char *rn,
const char *password)
/* first calculate 24 bytes ntlm response and then 16 byte session key */
int setup_ntlm_response(struct cifsSesInfo *ses)
{
char temp_key[16];
if ((key == NULL) || (rn == NULL))
unsigned int temp_len = CIFS_SESS_KEY_SIZE + CIFS_AUTH_RESP_SIZE;
char temp_key[CIFS_SESS_KEY_SIZE];

if (!ses)
return -EINVAL;

E_md4hash(password, temp_key);
mdfour(key->data.ntlm, temp_key, 16);
memcpy(key->data.ntlm+16, rn, CIFS_SESS_KEY_SIZE);
key->len = 40;
ses->auth_key.response = kmalloc(temp_len, GFP_KERNEL);
if (!ses->auth_key.response) {
cERROR(1, "NTLM can't allocate (%u bytes) memory", temp_len);
return -ENOMEM;
}
ses->auth_key.len = temp_len;

SMBNTencrypt(ses->password, ses->cryptKey,
ses->auth_key.response + CIFS_SESS_KEY_SIZE);

E_md4hash(ses->password, temp_key);
mdfour(ses->auth_key.response, temp_key, CIFS_SESS_KEY_SIZE);

return 0;
}

Expand Down Expand Up @@ -465,19 +475,13 @@ static int calc_ntlmv2_hash(struct cifsSesInfo *ses,
}

int
setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
const struct nls_table *nls_cp)
setup_ntlmv2_rsp(struct cifsSesInfo *ses, const struct nls_table *nls_cp)
{
int rc;
struct ntlmv2_resp *buf = (struct ntlmv2_resp *)resp_buf;
int baselen;
struct ntlmv2_resp *buf;
struct HMACMD5Context context;

buf->blob_signature = cpu_to_le32(0x00000101);
buf->reserved = 0;
buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
buf->reserved2 = 0;

if (ses->server->secType == RawNTLMSSP) {
if (!ses->domainName) {
rc = find_domain_name(ses);
Expand All @@ -494,22 +498,38 @@ setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
}
}

baselen = CIFS_SESS_KEY_SIZE + sizeof(struct ntlmv2_resp);
ses->auth_key.len = baselen + ses->tilen;
ses->auth_key.response = kmalloc(ses->auth_key.len, GFP_KERNEL);
if (!ses->auth_key.response) {
rc = ENOMEM;
cERROR(1, "%s: Can't allocate auth blob", __func__);
goto setup_ntlmv2_rsp_ret;
}

buf = (struct ntlmv2_resp *)
(ses->auth_key.response + CIFS_SESS_KEY_SIZE);
buf->blob_signature = cpu_to_le32(0x00000101);
buf->reserved = 0;
buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
buf->reserved2 = 0;

memcpy(ses->auth_key.response + baselen, ses->tiblob, ses->tilen);

/* calculate buf->ntlmv2_hash */
rc = calc_ntlmv2_hash(ses, nls_cp);
if (rc) {
cERROR(1, "could not get v2 hash rc %d", rc);
goto setup_ntlmv2_rsp_ret;
}
CalcNTLMv2_response(ses, resp_buf);
CalcNTLMv2_response(ses);

/* now calculate the session key for NTLMv2 */
hmac_md5_init_limK_to_64(ses->ntlmv2_hash, 16, &context);
hmac_md5_update(resp_buf, 16, &context);
hmac_md5_final(ses->auth_key.data.ntlmv2.key, &context);

memcpy(&ses->auth_key.data.ntlmv2.resp, resp_buf,
sizeof(struct ntlmv2_resp));
ses->auth_key.len = 16 + sizeof(struct ntlmv2_resp);
hmac_md5_update(ses->auth_key.response + CIFS_SESS_KEY_SIZE,
16, &context);
hmac_md5_final(ses->auth_key.response, &context);

return 0;

Expand All @@ -521,20 +541,17 @@ setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
return rc;
}

void CalcNTLMv2_response(const struct cifsSesInfo *ses,
char *v2_session_response)
void CalcNTLMv2_response(const struct cifsSesInfo *ses)
{
unsigned int offset = CIFS_SESS_KEY_SIZE + 8;
struct HMACMD5Context context;

/* rest of v2 struct already generated */
memcpy(v2_session_response + 8, ses->cryptKey, 8);
memcpy(ses->auth_key.response + offset, ses->cryptKey, 8);
hmac_md5_init_limK_to_64(ses->ntlmv2_hash, 16, &context);

hmac_md5_update(v2_session_response+8,
sizeof(struct ntlmv2_resp) - 8, &context);

if (ses->tilen)
hmac_md5_update(ses->tiblob, ses->tilen, &context);
hmac_md5_update(ses->auth_key.response + offset,
ses->auth_key.len - offset, &context);

hmac_md5_final(v2_session_response, &context);
/* cifs_dump_mem("v2_sess_rsp: ", v2_session_response, 32); */
hmac_md5_final(ses->auth_key.response + CIFS_SESS_KEY_SIZE, &context);
}
9 changes: 1 addition & 8 deletions fs/cifs/cifsglob.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -99,14 +99,7 @@ enum protocolEnum {

struct session_key {
unsigned int len;
union {
char ntlm[CIFS_SESS_KEY_SIZE + 16];
char krb5[CIFS_SESS_KEY_SIZE + 16]; /* BB: length correct? */
struct {
char key[16];
struct ntlmv2_resp resp;
} ntlmv2;
} data;
char *response;
};

struct cifs_cred {
Expand Down
7 changes: 6 additions & 1 deletion fs/cifs/cifspdu.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -130,10 +130,15 @@
*/
#define CIFS_CRYPTO_KEY_SIZE (8)

/*
* Size of the ntlm client response
*/
#define CIFS_AUTH_RESP_SIZE (24)

/*
* Size of the session key (crypto key encrypted with the password
*/
#define CIFS_SESS_KEY_SIZE (24)
#define CIFS_SESS_KEY_SIZE (16)

/*
* Maximum user name length
Expand Down
11 changes: 5 additions & 6 deletions fs/cifs/cifsproto.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -362,13 +362,12 @@ extern int cifs_sign_smb(struct smb_hdr *, struct TCP_Server_Info *, __u32 *);
extern int cifs_sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *,
__u32 *);
extern int cifs_verify_signature(struct smb_hdr *,
const struct session_key *session_key,
struct TCP_Server_Info *server,
__u32 expected_sequence_number);
extern int cifs_calculate_session_key(struct session_key *key, const char *rn,
const char *pass);
extern void CalcNTLMv2_response(const struct cifsSesInfo *, char *);
extern int setup_ntlmv2_rsp(struct cifsSesInfo *, char *,
const struct nls_table *);
extern void SMBNTencrypt(unsigned char *, unsigned char *, unsigned char *);
extern int setup_ntlm_response(struct cifsSesInfo *);
extern void CalcNTLMv2_response(const struct cifsSesInfo *);
extern int setup_ntlmv2_rsp(struct cifsSesInfo *, const struct nls_table *);
#ifdef CONFIG_CIFS_WEAK_PW_HASH
extern void calc_lanman_hash(const char *password, const char *cryptkey,
bool encrypt, char *lnm_session_key);
Expand Down
18 changes: 15 additions & 3 deletions fs/cifs/connect.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -175,6 +175,9 @@ cifs_reconnect(struct TCP_Server_Info *server)
}
server->sequence_number = 0;
server->session_estab = false;
kfree(server->session_key.response);
server->session_key.response = NULL;
server->session_key.len = 0;

spin_lock(&GlobalMid_Lock);
list_for_each(tmp, &server->pending_mid_q) {
Expand Down Expand Up @@ -1562,6 +1565,10 @@ cifs_put_tcp_session(struct TCP_Server_Info *server)

cifs_fscache_release_client_cookie(server);

kfree(server->session_key.response);
server->session_key.response = NULL;
server->session_key.len = 0;

task = xchg(&server->tsk, NULL);
if (task)
force_sig(SIGKILL, task);
Expand Down Expand Up @@ -3178,10 +3185,11 @@ int cifs_setup_session(unsigned int xid, struct cifsSesInfo *ses,
} else {
mutex_lock(&ses->server->srv_mutex);
if (!server->session_estab) {
memcpy(&server->session_key.data,
&ses->auth_key.data, ses->auth_key.len);
server->session_key.response = ses->auth_key.response;
server->session_key.len = ses->auth_key.len;
ses->server->session_estab = true;
server->sequence_number = 0x2;
server->session_estab = true;
ses->auth_key.response = NULL;
}
mutex_unlock(&server->srv_mutex);

Expand All @@ -3192,6 +3200,10 @@ int cifs_setup_session(unsigned int xid, struct cifsSesInfo *ses,
spin_unlock(&GlobalMid_Lock);
}

kfree(ses->auth_key.response);
ses->auth_key.response = NULL;
ses->auth_key.len = 0;

return rc;
}

Expand Down
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