CIFS: implement v3.11 preauth integrity

SMB3.11 clients must implement pre-authentification integrity.

* new mechanism to certify requests/responses happening before Tree
  Connect.
* supersedes VALIDATE_NEGOTIATE
* fixes signing for SMB3.11
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>

fs/cifs/cifsglob.h

@@ -675,7 +675,8 @@ struct TCP_Server_Info {
 	unsigned int	max_read;
 	unsigned int	max_write;
 #ifdef CONFIG_CIFS_SMB311
-	__u8	preauth_sha_hash[64]; /* save initital negprot hash */
+	 /* save initital negprot hash */
+	__u8	preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
 #endif /* 3.1.1 */
 	struct delayed_work reconnect; /* reconnect workqueue job */
 	struct mutex reconnect_mutex; /* prevent simultaneous reconnects */
@@ -864,7 +865,7 @@ struct cifs_ses {
 	__u8 smb3encryptionkey[SMB3_SIGN_KEY_SIZE];
 	__u8 smb3decryptionkey[SMB3_SIGN_KEY_SIZE];
 #ifdef CONFIG_CIFS_SMB311
-	__u8 preauth_sha_hash[64];
+	__u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
 #endif /* 3.1.1 */
 };
 

fs/cifs/smb2misc.c

@@ -706,3 +706,67 @@ smb2_handle_cancelled_mid(char *buffer, struct TCP_Server_Info *server)
 
 	return 0;
 }
+
+#ifdef CONFIG_CIFS_SMB311
+/**
+ * smb311_update_preauth_hash - update @ses hash with the packet data in @iov
+ *
+ * Assumes @iov does not contain the rfc1002 length and iov[0] has the
+ * SMB2 header.
+ */
+int
+smb311_update_preauth_hash(struct cifs_ses *ses, struct kvec *iov, int nvec)
+{
+	int i, rc;
+	struct sdesc *d;
+	struct smb2_sync_hdr *hdr;
+
+	if (ses->server->tcpStatus == CifsGood) {
+		/* skip non smb311 connections */
+		if (ses->server->dialect != SMB311_PROT_ID)
+			return 0;
+
+		/* skip last sess setup response */
+		hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
+		if (hdr->Flags & SMB2_FLAGS_SIGNED)
+			return 0;
+	}
+
+	rc = smb311_crypto_shash_allocate(ses->server);
+	if (rc)
+		return rc;
+
+	d = ses->server->secmech.sdescsha512;
+	rc = crypto_shash_init(&d->shash);
+	if (rc) {
+		cifs_dbg(VFS, "%s: could not init sha512 shash\n", __func__);
+		return rc;
+	}
+
+	rc = crypto_shash_update(&d->shash, ses->preauth_sha_hash,
+				 SMB2_PREAUTH_HASH_SIZE);
+	if (rc) {
+		cifs_dbg(VFS, "%s: could not update sha512 shash\n", __func__);
+		return rc;
+	}
+
+	for (i = 0; i < nvec; i++) {
+		rc = crypto_shash_update(&d->shash,
+					 iov[i].iov_base, iov[i].iov_len);
+		if (rc) {
+			cifs_dbg(VFS, "%s: could not update sha512 shash\n",
+				 __func__);
+			return rc;
+		}
+	}
+
+	rc = crypto_shash_final(&d->shash, ses->preauth_sha_hash);
+	if (rc) {
+		cifs_dbg(VFS, "%s: could not finalize sha512 shash\n",
+			 __func__);
+		return rc;
+	}
+
+	return 0;
+}
+#endif

fs/cifs/smb2pdu.c

@@ -453,6 +453,10 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 		return rc;
 
 	req->sync_hdr.SessionId = 0;
+#ifdef CONFIG_CIFS_SMB311
+	memset(server->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
+	memset(ses->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
+#endif
 
 	if (strcmp(ses->server->vals->version_string,
 		   SMB3ANY_VERSION_STRING) == 0) {
@@ -564,6 +568,15 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 
 	/* BB: add check that dialect was valid given dialect(s) we asked for */
 
+#ifdef CONFIG_CIFS_SMB311
+	/*
+	 * Keep a copy of the hash after negprot. This hash will be
+	 * the starting hash value for all sessions made from this
+	 * server.
+	 */
+	memcpy(server->preauth_sha_hash, ses->preauth_sha_hash,
+	       SMB2_PREAUTH_HASH_SIZE);
+#endif
 	/* SMB2 only has an extended negflavor */
 	server->negflavor = CIFS_NEGFLAVOR_EXTENDED;
 	/* set it to the maximum buffer size value we can send with 1 credit */
@@ -621,6 +634,10 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon)
 		return 0;
 #endif
 
+	/* In SMB3.11 preauth integrity supersedes validate negotiate */
+	if (tcon->ses->server->dialect == SMB311_PROT_ID)
+		return 0;
+
 	/*
 	 * validation ioctl must be signed, so no point sending this if we
 	 * can not sign it (ie are not known user).  Even if signing is not
@@ -1148,6 +1165,14 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 	sess_data->buf0_type = CIFS_NO_BUFFER;
 	sess_data->nls_cp = (struct nls_table *) nls_cp;
 
+#ifdef CONFIG_CIFS_SMB311
+	/*
+	 * Initialize the session hash with the server one.
+	 */
+	memcpy(ses->preauth_sha_hash, ses->server->preauth_sha_hash,
+	       SMB2_PREAUTH_HASH_SIZE);
+#endif
+
 	while (sess_data->func)
 		sess_data->func(sess_data);
 

fs/cifs/smb2pdu.h

@@ -264,6 +264,7 @@ struct smb2_negotiate_req {
 #define SMB311_SALT_SIZE			32
 /* Hash Algorithm Types */
 #define SMB2_PREAUTH_INTEGRITY_SHA512	cpu_to_le16(0x0001)
+#define SMB2_PREAUTH_HASH_SIZE 64
 
 struct smb2_preauth_neg_context {
 	__le16	ContextType; /* 1 */

fs/cifs/smb2proto.h

@@ -204,5 +204,7 @@ extern enum securityEnum smb2_select_sectype(struct TCP_Server_Info *,
 					enum securityEnum);
 #ifdef CONFIG_CIFS_SMB311
 extern int smb311_crypto_shash_allocate(struct TCP_Server_Info *server);
+extern int smb311_update_preauth_hash(struct cifs_ses *ses,
+				      struct kvec *iov, int nvec);
 #endif
 #endif			/* _SMB2PROTO_H */

fs/cifs/transport.c

@@ -37,6 +37,7 @@
 #include "cifsglob.h"
 #include "cifsproto.h"
 #include "cifs_debug.h"
+#include "smb2proto.h"
 #include "smbdirect.h"
 
 /* Max number of iovectors we can use off the stack when sending requests. */
@@ -751,6 +752,12 @@ cifs_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	if (rc < 0)
 		goto out;
 
+#ifdef CONFIG_CIFS_SMB311
+	if (ses->status == CifsNew)
+		smb311_update_preauth_hash(ses, rqst->rq_iov+1,
+					   rqst->rq_nvec-1);
+#endif
+
 	if (timeout == CIFS_ASYNC_OP)
 		goto out;
 
@@ -789,6 +796,16 @@ cifs_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	else
 		*resp_buf_type = CIFS_SMALL_BUFFER;
 
+#ifdef CONFIG_CIFS_SMB311
+	if (ses->status == CifsNew) {
+		struct kvec iov = {
+			.iov_base = buf + 4,
+			.iov_len = get_rfc1002_length(buf)
+		};
+		smb311_update_preauth_hash(ses, &iov, 1);
+	}
+#endif
+
 	credits = ses->server->ops->get_credits(midQ);
 
 	rc = ses->server->ops->check_receive(midQ, ses->server,