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>

1 files changed, 64 insertions, 0 deletions

diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index 76d03abaa38c..da012c3ab700 100644
--- a/fs/cifs/smb2misc.c
+++ b/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