On 12/5/25 14:58, Stefan Hanreich wrote:
On 12/5/25 2:02 PM, Robert Obkircher wrote:
On 12/5/25 12:58, Stefan Hanreich wrote:
Tested this in a similar vein as the nftables one:
* "normal" comments
* comments that are too long
* comments that are too long and do not truncate nicely at the 255
boundary
* comments in security groups
* emojis in comments
afaict the PVECOMMENT: prefix is merely visual? it doesn't serve any
functional purpose? At least a quick monkey-patch removing it didn't
break anything and judging from the source code it seems fine as well.
Imo it would be fine then to completely omit it then (even in the case
where rule comments start with PVESIG).
I think the parser in iptables_get_chains would at least temporarily set
an invalid signature on the chain and only override it later because the
real PVESIG: rule is always present and printed last. Relying on that
seemed a bit sketchy.
Do you mean the 'unknown' signature? Seems like this happens due to this
line here in the parser callback [1]. The other regex matches only
`PVESIG:` comments anyway.
If we remove the prefix, adding a comment with a `PVESIG:` prefix would
do that, I guess?
[1]
https://git.proxmox.com/?p=pve-firewall.git;a=blob;f=src/PVE/Firewall.pm;h=93f8c34466fd61bc646439275597aa24b8718053;hb=HEAD#l2093
I meant that without a prefix the other regex would match user comments
as well. E.g if I remove
- $comment = "PVECOMMENT:$comment"; # avoid any confusion with PVESIG
comments
and add:
} elsif ($line =~
m/^-A\s+(\S+)\s.*--comment\s+\"PVESIG:(\S+)\"/) {
my ($chain, $sig) = ($1, $2);
return if !&$is_pvefw_chain($chain);
+ print "$chain := $sig \n";
$res->{$chain} = $sig;
a rule like -A PVEFW-HOST-IN -j RETURN -m comment --comment
"PVESIG:abc" briefly sets $res->{chain} to abc:
PVEFW-HOST-IN := abc
PVEFW-HOST-IN := KeS6hbQXz4tEHemQqhJqOqWEWBA
mb someone with more experience with perl and utf-8 can chime in on the
truncation logic?
Tested-by: Stefan Hanreich <[email protected]>
On 12/1/25 1:33 PM, Robert Obkircher wrote:
Use the iptables comment extension to include comments from the UI.
Prefix them with "PVECOMMENT:" to avoid interfering with the existing
"PVESIG:$sig" comments, which are used to store signatures for change
detection.
The total length of the (unescaped) comments is limited to 255 utf8
bytes. According to the man page it could be up to 256 characters, but
the actual implementation seems to zero terminate the buffer before
saving. For example, the following command produces a 255 char comment
ending in 'a':
iptables -A PVEFW-HOST-IN -m comment --comment $(python3 -c
"print('ab'*256)")
Unlike the iptables command, this version truncates to valid utf8.
Signed-off-by: Robert Obkircher <[email protected]>
---
src/PVE/Firewall.pm | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/src/PVE/Firewall.pm b/src/PVE/Firewall.pm
index 93f8c34..688829a 100644
--- a/src/PVE/Firewall.pm
+++ b/src/PVE/Firewall.pm
@@ -2271,6 +2271,20 @@ sub ipt_gen_src_or_dst_match {
return $match;
}
+sub print_ipt_comment {
+ my ($comment) = @_;
+ return "" if !defined($comment) || $comment eq "";
+ $comment = encode("utf8", $comment, Encode::LEAVE_SRC);
+ $comment = "PVECOMMENT:$comment"; # avoid any confusion with
PVESIG comments
+
+ # man iptables-extensions says 256 chars, but the code only
saves 255
+ $comment = substr($comment, 0, 255);
+ $comment = encode('utf8', decode('utf8', $comment,
Encode::FB_QUIET | Encode::LEAVE_SRC));
+
+ $comment =~ s/[\\"']/\\$1/g; # escape logic from
xtables_save_string
seems like there is still an issue here - setting the comment `###"` I
get several:
Use of uninitialized value $1 in concatenation (.) or string at
/usr/share/perl5/PVE/Firewall.pm line 2284.
Can be easily checked via `pve-firewall compile`.
I think this had nothing to do with '#', I just forgot the capture group
in the substitution.
+ return " -m comment --comment \"$comment\""; # never omit quotes
because of the colon
+}
+
# convert a %rule to an array of iptables commands
sub ipt_rule_to_cmds {
my ($rule, $chain, $ipversion, $cluster_conf, $fw_conf, $vmid)
= @_;
@@ -2375,7 +2389,8 @@ sub ipt_rule_to_cmds {
my $logaction = get_log_rule_base($chain, $vmid, $rule-
{logmsg}, $loglevel);
push @iptcmds, "-A $chain $matchstr $logaction";
}
- push @iptcmds, "-A $chain $matchstr $targetstr";
+ my $comment = print_ipt_comment($rule->{comment});
+ push @iptcmds, "-A $chain $matchstr $targetstr$comment";
return @iptcmds;
}
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