From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [IPv6:2a01:7e0:0:424::9]) by lore.proxmox.com (Postfix) with ESMTPS id E53341FF17C for ; Tue, 16 Dec 2025 13:59:24 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 7E34AEBE2; Tue, 16 Dec 2025 14:00:11 +0100 (CET) From: Hannes Laimer To: pve-devel@lists.proxmox.com Date: Tue, 16 Dec 2025 14:00:05 +0100 Message-ID: <20251216130005.36544-1-h.laimer@proxmox.com> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1765889998896 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.054 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment RCVD_IN_VALIDITY_CERTIFIED_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to Validity was blocked. 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SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: [pve-devel] [PATCH pve-storage] cifs: fix connection check for kerberos authenticated shares X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Proxmox VE development discussion Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: pve-devel-bounces@lists.proxmox.com Sender: "pve-devel" With smbclient 4.22 (shipped with trixie) `-U Guest -N` does not fall back to not using a username at all, but just failed for shares where kerberos was used. smbclient 4.17 (shipped with bookworm) did fall back to anonymouse, which then succeeded if kbr was used. Since -U is never correct with kerberos and just worked because smbclient fell back to no user if `-U Guest` didn't work, we drop `-U` here. This fixes the connection check for cifs shares with kerberos. The most recent changes to when and how a fallback to no user is done in the smbclient was from 2016 (samba, 35051a860c75bc119e0ac7755bd69a9ea06695a1[1]). The handling of `-U` also didn't change between the two versions, also a change in default smb verion didn't seem to have happened in that timeframe either cause the last I could find was in 2019 (samba, 3264b1f317d6c603cc72eb2a150fe244c47aa3ac[2]). I did not find a conclusive answer for why exactly this stopped working, but given that we shouldn't use `-U Guest` with kerberos at all, this change would also make sense even if it would have continued working. We use the presence of `sec=krb5...` in the options to determine if kerberos is used. [1] https://gitlab.com/samba-team/samba/-/commit/35051a860c75bc119e0ac7755bd69a9ea06695a1 [2] https://gitlab.com/samba-team/samba/-/commit/3264b1f317d6c603cc72eb2a150fe244c47aa3ac Signed-off-by: Hannes Laimer --- this came up in support. I could also reproduce this locally, this patch fixes it. As to the concrete change between 4.17 and 4.22 that could have caused this I could not find something, so maybe someone who is more familiar with cifs, sepcifically in combination with kerberos, could take a look. src/PVE/Storage/CIFSPlugin.pm | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/src/PVE/Storage/CIFSPlugin.pm b/src/PVE/Storage/CIFSPlugin.pm index 5b35daf..5b61e67 100644 --- a/src/PVE/Storage/CIFSPlugin.pm +++ b/src/PVE/Storage/CIFSPlugin.pm @@ -66,6 +66,17 @@ sub get_cred_file { return undef; } +sub cifs_uses_kerberos : prototype($) { + my ($scfg) = @_; + + my $options = $scfg->{options}; + return 0 if !defined($options) || $options eq ''; + + $options =~ s/\s+//g; + + return $options =~ m/(?:^|,)sec=krb5(?:i|p)?(?:,|$)/i; +} + sub cifs_mount : prototype($$$$$) { my ($scfg, $storeid, $smbver, $user, $domain) = @_; @@ -77,7 +88,10 @@ sub cifs_mount : prototype($$$$$) { my $cmd = ['/bin/mount', '-t', 'cifs', $source, $mountpoint, '-o', 'soft', '-o']; - if (my $cred_file = get_cred_file($storeid)) { + if (cifs_uses_kerberos($scfg)) { + # no options needed for kerberos, adding username= or domain= would only be informal + # adding the if-branch here to have it explicit, and not just by not adding guest + } elsif (my $cred_file = get_cred_file($storeid)) { push @$cmd, "username=$user", '-o', "credentials=$cred_file"; push @$cmd, '-o', "domain=$domain" if defined($domain); } else { @@ -280,7 +294,9 @@ sub check_connection { push @$cmd, '-m', "smb" . int($scfg->{smbversion}); } - if (my $cred_file = get_cred_file($storeid)) { + if (cifs_uses_kerberos($scfg)) { + push @$cmd, '--use-kerberos=required'; + } elsif (my $cred_file = get_cred_file($storeid)) { push @$cmd, '-U', $scfg->{username}, '-A', $cred_file; push @$cmd, '-W', $scfg->{domain} if $scfg->{domain}; } else { -- 2.47.3 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel