encrypt the tcon itself if seal requested on mount and set encryption support for 3.11 properly

Commit Message

Steve French April 20, 2018, 10:11 p.m. UTC

This patch doesn't fix all the problems (mount with 3.11 and "seal"
fails presumably because the validate negotiate like hash for the
signature is not attached to the tcon the right way - signing is
usually disabled when encryption is enabled).

Should the signature be also included in the frame even if the tcon is
encryption in SMB3.11?

Comments

Pavel Shilovsky April 21, 2018, 12:14 a.m. UTC | #1

2018-04-20 15:11 GMT-07:00 Steve French via samba-technical
<[e-mail]>:
> This patch doesn't fix all the problems (mount with 3.11 and "seal"
> fails presumably because the validate negotiate like hash for the
> signature is not attached to the tcon the right way - signing is
> usually disabled when encryption is enabled).
>
> Should the signature be also included in the frame even if the tcon is
> encryption in SMB3.11?
>
>
> --
> Thanks,
>
> Steve


Looks good. Please also fix the encryption negotiate context:

static void
build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt)
{
pneg_ctxt->ContextType = SMB2_ENCRYPTION_CAPABILITIES;
pneg_ctxt->DataLength = cpu_to_le16(6);
pneg_ctxt->CipherCount = cpu_to_le16(2);
pneg_ctxt->Ciphers[0] = SMB2_ENCRYPTION_AES128_GCM;
pneg_ctxt->Ciphers[1] = SMB2_ENCRYPTION_AES128_CCM;
}

as we currently do not support AES128_GCM encryption. This is probably
why mount fails.

The SMB3 encryption includes signing, so, I think SMB2 header
signature may be omitted in validate negotiate if encryption is used.

We need to check if the current code works with CCM encryption for SMB
3.0 because there was a stable patch "Validate negotiate request mush
always be signed" that changed the behavior of validate negotiate
request.

Best regards,
Pavel Shilovsky
--
To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

From f1f488e9af87dc07f96769e4d834ccbea478e746 Mon Sep 17 00:00:00 2001
From: Steve French <[e-mail]>
Date: Fri, 20 Apr 2018 17:04:14 -0500
Subject: [PATCH] SMB3: Make sure encryption set for 3.11 and handle encrypted
 smb3 tcon

The tree connect request itself should be encrypted if the client
requests encryption ("seal" on mount), in addition we should be
enabling encryption in 3.11 based on whether we got any valid
encryption ciphers back in negprot (the corresponding session flag is
not set as it is in 3.0 and 3.02)

Signed-off-by: Steve French <[e-mail]>
CC: Stable <[e-mail]>
---
 fs/cifs/connect.c | 32 ++++++++++++++++----------------
 fs/cifs/smb2pdu.c |  1 +
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index e8830f076a7f..a5aa158d535a 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2959,6 +2959,22 @@  cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
 		}
 	}
 
+	if (volume_info->seal) {
+		if (ses->server->vals->protocol_id == 0) {
+			cifs_dbg(VFS,
+				 "SMB3 or later required for encryption\n");
+			rc = -EOPNOTSUPP;
+			goto out_fail;
+		} else if (tcon->ses->server->capabilities &
+					SMB2_GLOBAL_CAP_ENCRYPTION)
+			tcon->seal = true;
+		else {
+			cifs_dbg(VFS, "Encryption is not supported on share\n");
+			rc = -EOPNOTSUPP;
+			goto out_fail;
+		}
+	}
+
 	/*
 	 * BB Do we need to wrap session_mutex around this TCon call and Unix
 	 * SetFS as we do on SessSetup and reconnect?
@@ -3007,22 +3023,6 @@  cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
 		tcon->use_resilient = true;
 	}
 
-	if (volume_info->seal) {
-		if (ses->server->vals->protocol_id == 0) {
-			cifs_dbg(VFS,
-				 "SMB3 or later required for encryption\n");
-			rc = -EOPNOTSUPP;
-			goto out_fail;
-		} else if (tcon->ses->server->capabilities &
-					SMB2_GLOBAL_CAP_ENCRYPTION)
-			tcon->seal = true;
-		else {
-			cifs_dbg(VFS, "Encryption is not supported on share\n");
-			rc = -EOPNOTSUPP;
-			goto out_fail;
-		}
-	}
-
 	/*
 	 * We can have only one retry value for a connection to a share so for
 	 * resources mounted more than once to the same server share the last
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 0f044c4a2dc9..b8928e389147 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -444,6 +444,7 @@  static int decode_encrypt_ctx(struct TCP_Server_Info *server,
 		return -EINVAL;
 	}
 	server->cipher_type = ctxt->Ciphers[0];
+	server->capabilities |= SMB2_GLOBAL_CAP_ENCRYPTION;
 	return 0;
 }
 
-- 
2.14.1