From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
Enable signing in smb2. For smb2, hmac-sha256 is used instead
of hmac-md5 used for cifs/smb.
Signature field in smb2 header is 16 bytes instead of 8 bytes.
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
Signed-off-by: Pavel Shilovsky <piastryyy@xxxxxxxxx>
---
fs/cifs/Kconfig | 1 +
fs/cifs/cifsencrypt.c | 30 +++++++-
fs/cifs/cifsglob.h | 2 +
fs/cifs/smb2pdu.c | 39 +++++++++-
fs/cifs/smb2pdu.h | 3 +
fs/cifs/smb2proto.h | 4 +-
fs/cifs/smb2transport.c | 186 ++++++++++++++++++++++++++++++++++++++++++++--
7 files changed, 247 insertions(+), 18 deletions(-)
diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
index f66cc16..ed5452e 100644
--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -9,6 +9,7 @@ config CIFS
select CRYPTO_ARC4
select CRYPTO_ECB
select CRYPTO_DES
+ select CRYPTO_SHA256
help
This is the client VFS module for the Common Internet File System
(CIFS) protocol which is the successor to the Server Message Block
diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index 2cfb695..82e9d58 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -681,12 +681,17 @@ calc_seckey(struct cifs_ses *ses)
void
cifs_crypto_shash_release(struct TCP_Server_Info *server)
{
+ if (server->secmech.hmacsha256)
+ crypto_free_shash(server->secmech.hmacsha256);
+
if (server->secmech.md5)
crypto_free_shash(server->secmech.md5);
if (server->secmech.hmacmd5)
crypto_free_shash(server->secmech.hmacmd5);
+ kfree(server->secmech.sdeschmacsha256);
+
kfree(server->secmech.sdeschmacmd5);
kfree(server->secmech.sdescmd5);
@@ -711,6 +716,13 @@ cifs_crypto_shash_allocate(struct TCP_Server_Info *server)
goto crypto_allocate_md5_fail;
}
+ server->secmech.hmacsha256 = crypto_alloc_shash("hmac(sha256)", 0, 0);
+ if (IS_ERR(server->secmech.hmacsha256)) {
+ cERROR(1, "could not allocate crypto hmacsha256\n");
+ rc = PTR_ERR(server->secmech.hmacsha256);
+ goto crypto_allocate_hmacsha256_fail;
+ }
+
size = sizeof(struct shash_desc) +
crypto_shash_descsize(server->secmech.hmacmd5);
server->secmech.sdeschmacmd5 = kmalloc(size, GFP_KERNEL);
@@ -722,7 +734,6 @@ cifs_crypto_shash_allocate(struct TCP_Server_Info *server)
server->secmech.sdeschmacmd5->shash.tfm = server->secmech.hmacmd5;
server->secmech.sdeschmacmd5->shash.flags = 0x0;
-
size = sizeof(struct shash_desc) +
crypto_shash_descsize(server->secmech.md5);
server->secmech.sdescmd5 = kmalloc(size, GFP_KERNEL);
@@ -734,12 +745,29 @@ cifs_crypto_shash_allocate(struct TCP_Server_Info *server)
server->secmech.sdescmd5->shash.tfm = server->secmech.md5;
server->secmech.sdescmd5->shash.flags = 0x0;
+ size = sizeof(struct shash_desc) +
+ crypto_shash_descsize(server->secmech.hmacsha256);
+ server->secmech.sdeschmacsha256 = kmalloc(size, GFP_KERNEL);
+ if (!server->secmech.sdeschmacsha256) {
+ cERROR(1, "%s: Can't alloc hmacsha256\n", __func__);
+ rc = -ENOMEM;
+ goto crypto_allocate_hmacsha256_sdesc_fail;
+ }
+ server->secmech.sdeschmacsha256->shash.tfm = server->secmech.hmacsha256;
+ server->secmech.sdeschmacsha256->shash.flags = 0x0;
+
return 0;
+crypto_allocate_hmacsha256_sdesc_fail:
+ kfree(server->secmech.sdescmd5);
+
crypto_allocate_md5_sdesc_fail:
kfree(server->secmech.sdeschmacmd5);
crypto_allocate_hmacmd5_sdesc_fail:
+ crypto_free_shash(server->secmech.hmacsha256);
+
+crypto_allocate_hmacsha256_fail:
crypto_free_shash(server->secmech.md5);
crypto_allocate_md5_fail:
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 56962a5..520fe75 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -131,8 +131,10 @@ struct sdesc {
struct cifs_secmech {
struct crypto_shash *hmacmd5; /* hmac-md5 hash function */
struct crypto_shash *md5; /* md5 hash function */
+ struct crypto_shash *hmacsha256; /* hmac-sha256 hash function */
struct sdesc *sdeschmacmd5; /* ctxt to generate ntlmv2 hash, CR1 */
struct sdesc *sdescmd5; /* ctxt to generate cifs/smb signature */
+ struct sdesc *sdeschmacsha256; /* ctxt to generate smb2 signature */
};
/* per smb session structure/fields */
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 25d7ac2..ee7eec1 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -173,8 +173,7 @@ set_tcon_flags:
/* if (tcon->nocase)
buffer->Flags |= SMBFLG_CASELESS; */
if ((tcon->ses) && (tcon->ses->server))
- if (tcon->ses->server->sec_mode &
- SMB2_NEGOTIATE_SIGNING_REQUIRED)
+ if (tcon->ses->server->sec_mode & SECMODE_SIGN_REQUIRED)
buffer->Flags |= SMB2_FLAGS_SIGNED;
out:
smb->StructureSize2 = cpu_to_le16(parmsize);
@@ -661,6 +660,37 @@ SMB2_negotiate(unsigned int xid, struct cifs_ses *ses)
rc = -EIO;
goto neg_exit;
}
+
+ if ((sec_flags & CIFSSEC_MAY_SIGN) == 0) {
+ /* MUST_SIGN already includes the MAY_SIGN FLAG
+ so if this is zero it means that signing is disabled */
+ cFYI(1, "Signing disabled");
+ if (ses->server->sec_mode & SMB2_NEGOTIATE_SIGNING_REQUIRED) {
+ cERROR(1, "Server requires "
+ "packet signing to be enabled in "
+ "/proc/fs/cifs/SecurityFlags.");
+ rc = -EOPNOTSUPP;
+ }
+ ses->server->sec_mode &=
+ ~(SECMODE_SIGN_ENABLED | SECMODE_SIGN_REQUIRED);
+ } else if ((sec_flags & CIFSSEC_MUST_SIGN) == CIFSSEC_MUST_SIGN) {
+ /* signing required */
+ cFYI(1, "Must sign - sec_flags 0x%x", sec_flags);
+ if ((ses->server->sec_mode & (SMB2_NEGOTIATE_SIGNING_ENABLED |
+ SMB2_NEGOTIATE_SIGNING_REQUIRED)) == 0) {
+ cERROR(1, "signing required but server lacks support");
+ rc = -EOPNOTSUPP;
+ } else
+ ses->server->sec_mode
+ |= SECMODE_SIGN_REQUIRED;
+ } else {
+ /* signing optional ie CIFSSEC_MAY_SIGN */
+ if ((ses->server->sec_mode & SMB2_NEGOTIATE_SIGNING_REQUIRED)
+ == 0)
+ ses->server->sec_mode &=
+ ~(SECMODE_SIGN_ENABLED | SECMODE_SIGN_REQUIRED);
+ }
+
#ifdef CONFIG_SMB2_ASN1 /* BB REMOVEME when updated asn1.c ready */
rc = decode_neg_token_init(security_blob, blob_length,
&ses->server->sec_type);
@@ -933,7 +963,6 @@ SMB2_tcon(unsigned int xid, struct cifs_ses *ses,
pSMB2->hdr.smb2_buf_length =
cpu_to_be32(be32_to_cpu(pSMB2->hdr.smb2_buf_length)
- 1 /* pad */ + unc_path_len);
-
rc = smb2_sendrcv2(xid, ses, iov, 2, &resp_buftype /* ret */, &status,
CIFS_STD_OP | CIFS_LOG_ERROR);
cFYI(1, "tcon buftype %d rc %d status %d", resp_buftype, rc, status);
@@ -2476,9 +2505,9 @@ smb2_readv_callback(struct mid_q_entry *mid)
/* result already set, check signature */
if (server->sec_mode &
(SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
-/* if (smb2_verify_signature(mid->resp_buf, server))
+ if (smb2_verify_signature(mid->resp_buf, server))
cERROR(1, "Unexpected SMB signature");
-*/ }
+ }
/* FIXME: should this be counted toward the initiating task? */
task_io_account_read(rdata->bytes);
cifs_stats_bytes_read(tcon, rdata->bytes);
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index 3558057..d04e8b6 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -1058,4 +1058,7 @@ struct symlink_reparse_data_buf {
char pathbuffer[1];
} __attribute__((packed));
+#define SMB2_SIGNATURE_SIZE (16)
+#define SMB2_NTLMV2_SESSKEY_SIZE (16)
+#define SMB2_HMACSHA256_SIZE (32)
#endif /* _SMB2PDU_H */
diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index ef88f98..0425700 100644
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -93,9 +93,7 @@ extern int smb2_sendrcv_blocking(const unsigned int xid, struct cifs_tcon *tcon,
struct smb2_hdr *out_buf,
int *pbytes_returned);
extern int sign_smb2(struct kvec *iov, int n_vec, struct TCP_Server_Info *);
-/* BB FIXME - need to add SMB2's signing mechanism - not same as CIFS BB */
-/*extern int smb2_verify_signature(struct smb2_hdr *,
- const struct mac_key *mac_key);*/
+extern int smb2_verify_signature(struct smb2_hdr *, struct TCP_Server_Info *);
extern void smb2_echo_request(struct work_struct *work);
extern int smb2_demultiplex_thread(struct TCP_Server_Info *server);
extern int smb2_observe_thread(struct TCP_Server_Info *server);
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index adb701f..acdd0c6 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -37,6 +37,178 @@
extern mempool_t *smb2_mid_poolp;
+static int
+smb2_calc_signature(struct smb2_hdr *smb2_pdu, struct TCP_Server_Info *server,
+ char *signature)
+{
+ int rc;
+ unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
+ unsigned char *sigptr = smb2_signature;
+
+ memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE);
+ memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);
+
+ rc = crypto_shash_setkey(server->secmech.hmacsha256,
+ server->session_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
+ if (rc) {
+ cERROR(1, "%s: Could not update with response\n", __func__);
+ return rc;
+ }
+
+ rc = crypto_shash_init(&server->secmech.sdeschmacsha256->shash);
+ if (rc) {
+ cERROR(1, "%s: Could not init md5\n", __func__);
+ return rc;
+ }
+
+ rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+ smb2_pdu->ProtocolId,
+ be32_to_cpu(smb2_pdu->smb2_buf_length));
+ if (rc) {
+ cERROR(1, "%s: Could not update with payload\n", __func__);
+ return rc;
+ }
+
+ rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
+ sigptr);
+ if (rc)
+ cERROR(1, "%s: Could not generate sha256 hash\n", __func__);
+
+ memcpy(smb2_pdu->Signature, sigptr, SMB2_NTLMV2_SESSKEY_SIZE);
+
+ return rc;
+}
+
+static int
+smb2_calc_signature2(const struct kvec *iov, int n_vec,
+ struct TCP_Server_Info *server, struct smb2_hdr *smb2_pdu)
+{
+ int i, rc;
+ unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
+ unsigned char *sigptr = smb2_signature;
+
+ memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE);
+ memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);
+
+ rc = crypto_shash_setkey(server->secmech.hmacsha256,
+ server->session_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
+ if (rc) {
+ cERROR(1, "%s: Could not update with response\n", __func__);
+ return rc;
+ }
+
+ rc = crypto_shash_init(&server->secmech.sdeschmacsha256->shash);
+ if (rc) {
+ cERROR(1, "%s: Could not init md5\n", __func__);
+ return rc;
+ }
+
+ for (i = 0; i < n_vec; i++) {
+ if (iov[i].iov_len == 0)
+ continue;
+ if (iov[i].iov_base == NULL) {
+ cERROR(1, "null iovec entry");
+ return -EIO;
+ }
+ /*
+ * The first entry includes a length field (which does not get
+ * signed that occupies the first 4 bytes before the header
+ */
+ if (i == 0) {
+ if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
+ break; /* nothing to sign or corrupt header */
+ rc =
+ crypto_shash_update(
+ &server->secmech.sdeschmacsha256->shash,
+ iov[i].iov_base + 4, iov[i].iov_len - 4);
+ } else {
+ rc =
+ crypto_shash_update(
+ &server->secmech.sdeschmacsha256->shash,
+ iov[i].iov_base, iov[i].iov_len);
+ }
+ if (rc) {
+ cERROR(1, "%s: Could not update with payload\n",
+ __func__);
+ return rc;
+ }
+ }
+
+ rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
+ sigptr);
+ if (rc)
+ cERROR(1, "%s: Could not generate sha256 hash\n", __func__);
+
+ memcpy(smb2_pdu->Signature, sigptr, SMB2_NTLMV2_SESSKEY_SIZE);
+
+ return rc;
+}
+
+/* must be called with server->srv_mutex held */
+static int smb2_sign_smb2(struct kvec *iov, int n_vec,
+ struct TCP_Server_Info *server)
+{
+ int rc = 0;
+ struct smb2_hdr *smb2_pdu = iov[0].iov_base;
+
+ if (!(smb2_pdu->Flags & SMB2_FLAGS_SIGNED) ||
+ server->tcpStatus == CifsNeedNegotiate)
+ return rc;
+
+ if (!server->session_estab) {
+ strncpy(smb2_pdu->Signature, "BSRSPYL", 8);
+ return rc;
+ }
+
+ rc = smb2_calc_signature2(iov, n_vec, server, smb2_pdu);
+
+ return rc;
+}
+
+int
+smb2_verify_signature(struct smb2_hdr *smb2_pdu, struct TCP_Server_Info *server)
+{
+ unsigned int rc;
+ char server_response_sig[16];
+ char what_we_think_sig_should_be[20];
+
+ if ((smb2_pdu->Command == SMB2_NEGOTIATE) ||
+ (smb2_pdu->Command == SMB2_OPLOCK_BREAK) ||
+ (!server->session_estab))
+ return 0;
+
+ /*
+ * BB what if signatures are supposed to be on for session but
+ * server does not send one? BB
+ */
+
+ /* Do not need to verify session setups with signature "BSRSPYL " */
+ if (memcmp(smb2_pdu->Signature, "BSRSPYL ", 8) == 0)
+ cFYI(1, "dummy signature received for smb command 0x%x",
+ smb2_pdu->Command);
+
+ /*
+ * Save off the origiginal signature so we can modify the smb and check
+ * our calculated signature against what the server sent
+ */
+ memcpy(server_response_sig, smb2_pdu->Signature, 16);
+
+ memset(smb2_pdu->Signature, 0, 16);
+
+ rc = smb2_calc_signature(smb2_pdu, server, what_we_think_sig_should_be);
+
+ if (rc)
+ return rc;
+
+/* smb2_dump_mem("what we think it should be: ",
+ what_we_think_sig_should_be, 16); */
+
+ if (memcmp(server_response_sig, what_we_think_sig_should_be, 8))
+ return -EACCES;
+ else
+ return 0;
+
+}
/*
* Set message id for the request. Should be called after wait_for_free_response
* and locking srv_mutex. iov array must have at least 1 element.
@@ -283,12 +455,8 @@ smb2_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
/* convert the length into a more usable form */
if ((receive_len > 24) &&
(server->sec_mode & SMB2_NEGOTIATE_SIGNING_REQUIRED)) {
- /* BB fixme */
- /*rc = smb2_verify_signature(mid->resp_buf,
- &ses->server->mac_signing_key);
- if (rc) {
+ if (smb2_verify_signature(mid->resp_buf, server))
cERROR(1, "Unexpected SMB signature");
- } */
}
return map_smb2_to_linux_error(mid->resp_buf, log_error);
@@ -353,12 +521,13 @@ smb2_sendrcv2(const unsigned int xid, struct cifs_ses *ses,
wake_up(&ses->server->request_q);
return rc;
}
- /* rc = sign_smb2(iov, n_vec, ses->server); BB
+
+ rc = smb2_sign_smb2(iov, n_vec, ses->server);
if (rc) {
mutex_unlock(&ses->server->srv_mutex);
cifs_small_buf_release(buf);
goto out;
- } */
+ }
midQ->mid_state = MID_REQUEST_SUBMITTED;
cifs_in_send_inc(ses->server);
@@ -479,12 +648,11 @@ smb2_call_async(struct TCP_Server_Info *server, struct kvec *iov,
list_add_tail(&mid->qhead, &server->pending_mid_q);
spin_unlock(&GlobalMid_Lock);
-/* rc = cifs_sign_smb2(iov, nvec, server, &mid->sequence_number);
+ rc = smb2_sign_smb2(iov, nvec, server);
if (rc) {
mutex_unlock(&server->srv_mutex);
goto out_err;
}
-*/
mid->receive = receive;
mid->callback = callback;
--
1.7.1
--
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