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
From 16fcf9422d70cb28056518b30c377fe88a7ad7b9 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
---
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
From 9984843c7cb5be498c3fea50e9fa016dc44424ef Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
---
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
From a2bdd5ceb7090ea4f3ee091da2418f23d270b391 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx> # v5.8+
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
---
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
