From: Thomas Lamprecht <t.lamprecht@proxmox.com>
Date: Tue, 14 Sep 2021 14:23:23 +0000 (+0200)
Subject: cifs: negotiates the highest SMB2+ version supported by default
X-Git-Url: https://git.proxmox.com/?p=pve-storage.git;a=commitdiff_plain;h=e1667a225310d96ae9ce813d53ec9b04eebe77e6

cifs: negotiates the highest SMB2+ version supported by default

instead of hardcoding it to a potential outdated value.

For `smbclient` we only set max-protocol version and that could only
be smb2 or smb3 (no finer granularity) any how, so this was not
really correct.

Nowadays the kernel dropped SMB1 and tries to go for SMB2.1 or higher
by default, depending on what client and server supports. SMB2.1 is
Windows 7/2008R2 - both EOL since quite a bit, so ok as default lower
boundary.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---

diff --git a/PVE/Storage/CIFSPlugin.pm b/PVE/Storage/CIFSPlugin.pm
index 565fb78..c5f3894 100644
--- a/PVE/Storage/CIFSPlugin.pm
+++ b/PVE/Storage/CIFSPlugin.pm
@@ -78,7 +78,7 @@ sub cifs_mount {
 	push @$cmd, 'guest,username=guest';
     }
 
-    push @$cmd, '-o', defined($smbver) ? "vers=$smbver" : "vers=3.0";
+    push @$cmd, '-o', defined($smbver) ? "vers=$smbver" : "vers=default";
 
     run_command($cmd, errmsg => "mount error");
 }
@@ -115,8 +115,10 @@ sub properties {
 	    maxLength => 256,
 	},
 	smbversion => {
-	    description => "SMB protocol version",
+	    description => "SMB protocol version. 'default' if not set, negotiates the highest SMB2+"
+	        ." version supported by both the client and server.",
 	    type => 'string',
+	    default => 'default',
 	    enum => ['default', '2.0', '2.1', '3', '3.0', '3.11'],
 	    optional => 1,
 	},
@@ -255,9 +257,12 @@ sub check_connection {
 
     my $servicename = '//'.$scfg->{server}.'/'.$scfg->{share};
 
-    my $cmd = ['/usr/bin/smbclient', $servicename, '-d', '0', '-m'];
+    my $cmd = ['/usr/bin/smbclient', $servicename, '-d', '0'];
 
-    push @$cmd, $scfg->{smbversion} ? "smb".int($scfg->{smbversion}) : 'smb3';
+    if (defined($scfg->{smbversion}) && $scfg->{smbversion} ne 'default') {
+	# max-protocol version, so basically only relevant for smb2 vs smb3
+	push @$cmd, '-m', "smb" . int($scfg->{smbversion});
+    }
 
     if (my $cred_file = get_cred_file($storeid)) {
 	push @$cmd, '-U', $scfg->{username}, '-A', $cred_file;