lei-daemon: do not leak FDs on bogus requests

If a client passes us the incorrect number of FDs, we'll vivify
them into PerlIO objects so they can be auto-closed.  Using
POSIX::close was considered, but it would've been more code to
handle an uncommon case.

2 files changed, 36 insertions, 8 deletions

diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index 878685f1..e5211764 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -981,17 +981,16 @@ sub accept_dispatch { # Listener {post_accept} callback
                 return send($sock, 'timed out waiting to recv FDs', MSG_EOR);
         # (4096 * 33) >MAX_ARG_STRLEN
         my @fds = $recv_cmd->($sock, my $buf, 4096 * 33) or return; # EOF
-        if (scalar(@fds) == 4) {
-                for my $i (0..3) {
-                        my $fd = shift(@fds);
-                        open($self->{$i}, '+<&=', $fd) and next;
-                        send($sock, "open(+<&=$fd) (FD=$i): $!", MSG_EOR);
-                }
-        } elsif (!defined($fds[0])) {
+        if (!defined($fds[0])) {
                 warn(my $msg = "recv_cmd failed: $!");
                 return send($sock, $msg, MSG_EOR);
         } else {
-                return;
+                my $i = 0;
+                for my $fd (@fds) {
+                        open($self->{$i++}, '+<&=', $fd) and next;
+                        send($sock, "open(+<&=$fd) (FD=$i): $!", MSG_EOR);
+                }
+                return if scalar(@fds) != 4;
         }
         $self->{2}->autoflush(1); # keep stdout buffered until x_it|DESTROY
         # $ENV_STR = join('', map { "\0$_=$ENV{$_}" } keys %ENV);
diff --git a/t/lei-daemon.t b/t/lei-daemon.t
index c30e5ac1..35e059b9 100644
--- a/t/lei-daemon.t
+++ b/t/lei-daemon.t
@@ -2,8 +2,16 @@
 # Copyright (C) 2020-2021 all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 use strict; use v5.10.1; use PublicInbox::TestCommon;
+use Socket qw(AF_UNIX SOCK_SEQPACKET MSG_EOR pack_sockaddr_un);
+use PublicInbox::Spawn qw(which);
 
 test_lei({ daemon_only => 1 }, sub {
+        my $send_cmd = PublicInbox::Spawn->can('send_cmd4') // do {
+                require PublicInbox::CmdIPC4;
+                PublicInbox::CmdIPC4->can('send_cmd4');
+        };
+        $send_cmd or BAIL_OUT 'started testing lei-daemon w/o send_cmd4!';
+
         my $sock = "$ENV{XDG_RUNTIME_DIR}/lei/5.seq.sock";
         my $err_log = "$ENV{XDG_RUNTIME_DIR}/lei/errors.log";
         lei_ok('daemon-pid');
@@ -22,6 +30,27 @@ test_lei({ daemon_only => 1 }, sub {
         is($pid, $pid_again, 'daemon-pid idempotent');
         like($lei_err, qr/phail/, 'got mock "phail" error previous run');
 
+        SKIP: {
+                skip 'only testing open files on Linux', 1 if $^O ne 'linux';
+                my $d = "/proc/$pid/fd";
+                skip "no $d on Linux" unless -d $d;
+                my @before = sort(glob("$d/*"));
+                my $addr = pack_sockaddr_un($sock);
+                open my $null, '<', '/dev/null' or BAIL_OUT "/dev/null: $!";
+                my @fds = map { fileno($null) } (0..2);
+                for (0..10) {
+                        socket(my $c, AF_UNIX, SOCK_SEQPACKET, 0) or
+                                                        BAIL_OUT "socket: $!";
+                        connect($c, $addr) or BAIL_OUT "connect: $!";
+                        $send_cmd->($c, \@fds, 'hi',  MSG_EOR);
+                }
+                lei_ok('daemon-pid');
+                chomp($pid = $lei_out);
+                is($pid, $pid_again, 'pid unchanged after failed reqs');
+                my @after = sort(glob("$d/*"));
+                is_deeply(\@before, \@after, 'open files unchanged') or
+                        diag explain([\@before, \@after]);;
+        }
         lei_ok(qw(daemon-kill));
         is($lei_out, '', 'no output from daemon-kill');
         is($lei_err, '', 'no error from daemon-kill');