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From: Steve French <smfrench@gmail.com>
To: "Aurélien Aptel" <aaptel@suse.com>,
	"Shyam Prasad N" <nspmangalore@gmail.com>
Cc: CIFS <linux-cifs@vger.kernel.org>
Subject: [PATCH][SMB3] 3 small multichannel client patches
Date: Fri, 7 May 2021 20:13:01 -0500	[thread overview]
Message-ID: <CAH2r5mu3m6FWWqrfOeQugXWGZOPiEE+Xgk8wc0rn8OgLRVPSWQ@mail.gmail.com> (raw)

[-- Attachment #1: Type: text/plain, Size: 287 bytes --]

1) we were not setting CAP_MULTICHANNEL on negotiate request
2) we were ignoring whether the server set CAP_NEGOTIATE in the response
3) we were silently ignoring multichannel when "max_channels" was > 1
but the user forgot to include "multichannel" in mount line.



-- 
Thanks,

Steve

[-- Attachment #2: 0002-smb3-if-max_channels-set-to-more-than-one-channel-re.patch --]
[-- Type: text/x-patch, Size: 1231 bytes --]

From 16fcf9422d70cb28056518b30c377fe88a7ad7b9 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Fri, 7 May 2021 19:33:51 -0500
Subject: [PATCH 2/4] smb3: if max_channels set to more than one channel
 request multichannel

Mounting with "multichannel" is obviously implied if user requested
more than one channel on mount (ie mount parm max_channels>1).
Currently both have to be specified. Fix that so that if max_channels
is greater than 1 on mount, enable multichannel rather than silently
falling back to non-multichannel.

Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/fs_context.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
index 3bcf881c3ae9..8f7af6fcdc76 100644
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -1021,6 +1021,9 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
 			goto cifs_parse_mount_err;
 		}
 		ctx->max_channels = result.uint_32;
+		/* If more than one channel requested ... they want multichan */
+		if ((ctx->multichannel == false) && (result.uint_32 > 1))
+			ctx->multichannel = true;
 		break;
 	case Opt_handletimeout:
 		ctx->handle_timeout = result.uint_32;
-- 
2.27.0


[-- Attachment #3: 0003-smb3-do-not-attempt-multichannel-to-server-which-doe.patch --]
[-- Type: text/x-patch, Size: 1120 bytes --]

From 9984843c7cb5be498c3fea50e9fa016dc44424ef Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Fri, 7 May 2021 20:00:41 -0500
Subject: [PATCH 3/4] smb3: do not attempt multichannel to server which does
 not support it

We were ignoring CAP_MULTI_CHANNEL in the server response - if the
server doesn't support multichannel we should not be attempting it.

See MS-SMB2 section 3.2.5.2

Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/sess.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 63d517b9f2ff..a391ca3166f3 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -97,6 +97,12 @@ int cifs_try_adding_channels(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses)
 		return 0;
 	}
 
+	if ((ses->server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL) == false) {
+		cifs_dbg(VFS, "server does not support CAP_MULTI_CHANNEL, multichannel disabled\n");
+		ses->chan_max = 1;
+		return 0;
+	}
+
 	/*
 	 * Make a copy of the iface list at the time and use that
 	 * instead so as to not hold the iface spinlock for opening
-- 
2.27.0


[-- Attachment #4: 0001-smb3-when-mounting-with-multichannel-include-it-in-r.patch --]
[-- Type: text/x-patch, Size: 1641 bytes --]

From a2bdd5ceb7090ea4f3ee091da2418f23d270b391 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Fri, 7 May 2021 18:24:11 -0500
Subject: [PATCH 1/4] smb3: when mounting with multichannel include it in
 requested capabilities

In the SMB3/SMB3.1.1 negotiate protocol request, we are supposed to
advertise CAP_MULTICHANNEL capability when establishing multiple
channels has been requested by the user doing the mount. See MS-SMB2
sections 2.2.3 and 3.2.5.2

Without setting it there is some risk that multichannel could fail
if the server interpreted the field strictly.

Cc: <stable@vger.kernel.org> # v5.8+
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/smb2pdu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index e36c2a867783..a8bf43184773 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -841,6 +841,8 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 		req->SecurityMode = 0;
 
 	req->Capabilities = cpu_to_le32(server->vals->req_capabilities);
+	if (ses->chan_max > 1)
+		req->Capabilities |= cpu_to_le32(SMB2_GLOBAL_CAP_MULTI_CHANNEL);
 
 	/* ClientGUID must be zero for SMB2.02 dialect */
 	if (server->vals->protocol_id == SMB20_PROT_ID)
@@ -1032,6 +1034,9 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon)
 
 	pneg_inbuf->Capabilities =
 			cpu_to_le32(server->vals->req_capabilities);
+	if (tcon->ses->chan_max > 1)
+		pneg_inbuf->Capabilities |= cpu_to_le32(SMB2_GLOBAL_CAP_MULTI_CHANNEL);
+
 	memcpy(pneg_inbuf->Guid, server->client_guid,
 					SMB2_CLIENT_GUID_SIZE);
 
-- 
2.27.0


             reply	other threads:[~2021-05-08  1:13 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-08  1:13 Steve French [this message]
2021-05-08 12:30 ` [PATCH][SMB3] 3 small multichannel client patches Shyam Prasad N
2021-05-08 13:29 ` Tom Talpey
2021-05-08 15:10   ` Steve French
2021-05-08 15:20     ` Tom Talpey
2021-05-08 15:51       ` Steve French
2021-05-11 15:53 ` Aurélien Aptel

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