/usr/sbin/amavis-mc is in amavisd-new 1:2.10.1-2~deb8u1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
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#------------------------------------------------------------------------------
# This is amavis-mc, a master (of ceremonies) processes to supervise
# supporting service processes (such as amavis-services) used by amavisd-new.
#
# Author: Mark Martinec <Mark.Martinec@ijs.si>
#
# Copyright (c) 2012-2014, Mark Martinec
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
# The views and conclusions contained in the software and documentation are
# those of the authors and should not be interpreted as representing official
# policies, either expressed or implied, of the Jozef Stefan Institute.
# (the above license is the 2-clause BSD license, also known as
# a "Simplified BSD License", and pertains to this program only)
#
# Patches and problem reports are welcome.
# The latest version of this program is available at:
# http://www.ijs.si/software/amavisd/
#------------------------------------------------------------------------------
use strict;
use re 'taint';
use warnings;
use warnings FATAL => qw(utf8 void);
no warnings 'uninitialized';
use vars qw($VERSION); $VERSION = 2.008002;
use vars qw($myproduct_name $myversion_id $myversion_date $myversion);
BEGIN {
$myproduct_name = 'amavis-mc';
$myversion_id = '2.9.0'; $myversion_date = '20140506';
$myversion = "$myproduct_name-$myversion_id ($myversion_date)";
}
use Errno qw(ESRCH ENOENT);
use POSIX qw(:sys_wait_h
WIFEXITED WIFSIGNALED WIFSTOPPED WEXITSTATUS WTERMSIG WSTOPSIG);
use Time::HiRes qw(time);
use IO::File qw(O_RDONLY O_WRONLY O_RDWR O_APPEND O_CREAT O_EXCL);
use Unix::Syslog qw(:macros :subs);
use vars qw(@path @services $daemon_user $daemon_group $pid_file $log_level
$syslog_ident $syslog_facility);
### USER CONFIGURABLE:
$daemon_user = 'amavis';
$daemon_group = 'amavis';
$pid_file = '/var/run/amavis/amavis-mc.pid';
$log_level = 0;
$syslog_ident = 'amavis-mc';
$syslog_facility = LOG_MAIL;
@path = qw(/usr/local/sbin /usr/local/bin /usr/sbin /sbin /usr/bin /bin);
@services = (
{ cmd => 'amavis-services msg-forwarder' },
{ cmd => 'amavis-services childproc-minder' },
{ cmd => 'amavis-services snmp-responder' },
);
### END OF USER CONFIGURABLE
my($interrupted, $syslog_open, $pid_file_created, @pids_exited, %pid2service);
# Return untainted copy of a string (argument can be a string or a string ref)
#
sub untaint($) {
return undef if !defined $_[0]; # must return undef even in a list context!
no re 'taint';
local $1; # avoid Perl taint bug: tainted global $1 propagates taintedness
(ref($_[0]) ? ${$_[0]} : $_[0]) =~ /^(.*)\z/s;
$1;
}
# is message log level below the current log level (i.e. eligible for logging)?
#
sub ll($) {
my($level) = @_;
$level <= $log_level;
}
sub do_log($$;@) {
# my($level,$errmsg,@args) = @_;
my $level = shift;
if ($level <= $log_level) {
my $errmsg = shift;
# treat $errmsg as sprintf format string if additional arguments provided
$errmsg = sprintf($errmsg,@_) if @_;
if (!$syslog_open) {
$errmsg .= "\n";
print STDERR $errmsg; # print ignoring I/O status, except SIGPIPE
} else {
my $prio = $level >= 3 ? LOG_DEBUG # most frequent first
: $level >= 1 ? LOG_INFO
: $level >= 0 ? LOG_NOTICE
: $level >= -1 ? LOG_WARNING
: LOG_ERR;
syslog($prio, "%s", $errmsg);
}
}
}
sub find_program_path($$) {
my($fv_list, $path_list_ref) = @_;
$fv_list = [$fv_list] if !ref $fv_list;
my $found;
for my $fv (@$fv_list) { # search through alternatives
my(@fv_cmd) = split(' ',$fv);
my $cmd = $fv_cmd[0];
if (!@fv_cmd) {
# empty, not available
} elsif ($cmd =~ m{^/}s) { # absolute path
my $errn = stat($cmd) ? 0 : 0+$!;
if ($errn == ENOENT) {
# file does not exist
} elsif ($errn) {
do_log(-1, "find_program_path: %s inaccessible: %s", $cmd,$!);
} elsif (-d _) {
do_log(0, "find_program_path: %s is a directory", $cmd);
} elsif (!-x _) {
do_log(0, "find_program_path: %s is not executable", $cmd);
} else {
$found = join(' ', @fv_cmd);
}
} elsif ($cmd =~ m{/}s) { # relative path
die "find_program_path: relative paths not implemented: @fv_cmd\n";
} else { # walk through the specified PATH
for my $p (@$path_list_ref) {
my $errn = stat("$p/$cmd") ? 0 : 0+$!;
if ($errn == ENOENT) {
# file does not exist
} elsif ($errn) {
do_log(-1, "find_program_path: %s/%s inaccessible: %s", $p,$cmd,$!);
} elsif (-d _) {
do_log(0, "find_program_path: %s/%s is a directory", $p,$cmd);
} elsif (!-x _) {
do_log(0, "find_program_path: %s/%s is not executable", $p,$cmd);
} else {
$found = $p . '/' . join(' ', @fv_cmd);
last;
}
}
}
last if defined $found;
}
$found;
}
# drop privileges
#
sub drop_priv($$) {
my($desired_user,$desired_group) = @_;
local($1);
my($username,$passwd,$uid,$gid) =
$desired_user=~/^(\d+)$/ ? (undef,undef,$1,undef) :getpwnam($desired_user);
defined $uid or die "drop_priv: No such username: $desired_user\n";
if (!defined($desired_group) || $desired_group eq '') {
$desired_group = $gid; # for logging purposes
}
else { $gid = $desired_group=~/^(\d+)$/ ? $1 : getgrnam($desired_group) }
defined $gid or die "drop_priv: No such group: $desired_group\n";
$( = $gid; $) = "$gid $gid"; # real and effective GID
POSIX::setgid($gid) or die "drop_priv: Can't setgid to $gid: $!";
POSIX::setuid($uid) or die "drop_priv: Can't setuid to $uid: $!";
$> = $uid; $< = $uid; # just in case
# print STDERR "desired user=$desired_user ($uid), current: EUID: $> ($<)\n";
# print STDERR "desired group=$desired_group ($gid), current: EGID: $) ($()\n";
$> != 0 or die "drop_priv: Still running as root, aborting\n";
$< != 0 or die "Effective UID changed, but Real UID is 0, aborting\n";
}
sub daemonize() {
closelog() if $syslog_open;
$syslog_open = 0;
STDOUT->autoflush(1);
STDERR->autoflush(1);
close(STDIN) or die "Can't close STDIN: $!";
my $pid;
# the first fork allows the shell to return and allows doing a setsid
eval { $pid = fork(); 1 }
or do {
my($eval_stat) = $@ ne '' ? $@ : "errno=$!"; chomp $eval_stat;
die "Error forking #1: $eval_stat";
};
defined $pid or die "Can't fork #1: $!";
if ($pid) { # parent process terminates here
POSIX::_exit(0); # avoid END and destructor processing
}
# disassociate from a controlling terminal
my $pgid = POSIX::setsid();
defined $pgid && $pgid >= 0 or die "Can't start a new session: $!";
# We are now a session leader. As a session leader, opening a file
# descriptor that is a terminal will make it our controlling terminal.
# The second fork makes us NOT a session leader. Only session leaders
# can acquire a controlling terminal, so we may now open up any file
# we wish without worrying that it will become a controlling terminal.
# second fork prevents from accidentally reacquiring a controlling terminal
eval { $pid = fork(); 1 }
or do {
my($eval_stat) = $@ ne '' ? $@ : "errno=$!"; chomp $eval_stat;
die "Error forking #2: $eval_stat";
};
defined $pid or die "Can't fork #2: $!";
if ($pid) { # parent process terminates here
POSIX::_exit(0); # avoid END and destructor processing
}
chdir('/') or die "Can't chdir to '/': $!";
# a daemonized child process, live long and prosper...
do_log(2, "Daemonized as process [%s]", $$);
openlog($syslog_ident, LOG_PID | LOG_NDELAY, $syslog_facility);
$syslog_open = 1;
{ # suppress unnecessary warning:
# "Filehandle STDIN reopened as STDOUT only for output"
# See https://rt.perl.org/rt3/Public/Bug/Display.html?id=23838
no warnings 'io';
close(STDOUT) or die "Can't close STDOUT: $!";
open(STDOUT, '>/dev/null') or die "Can't open /dev/null: $!";
close(STDERR) or die "Can't close STDERR: $!";
open(STDERR, '>&STDOUT') or die "Can't dup STDOUT: $!";
}
}
# Run specified command as a subprocess.
# Return a process id of a child process.
#
sub spawn_command($@) {
my($cmd, @args) = @_;
my $cmd_text = join(' ', $cmd, @args);
my $pid;
eval {
# Note that fork(2) returns ENOMEM on lack of swap space, and EAGAIN when
# process limit is reached; we want it to fail in both cases and not obey
# the EAGAIN and keep retrying, as perl open() does.
$pid = fork(); 1;
} or do {
my $eval_stat = $@ ne '' ? $@ : "errno=$!"; chomp $eval_stat;
die "spawn_command (forking): $eval_stat";
};
defined($pid) or die "spawn_command: can't fork: $!";
if (!$pid) { # child
alarm(0); my $interrupt = '';
my $h1 = sub { $interrupt = $_[0] };
my $h2 = sub { die "Received signal ".$_[0] };
@SIG{qw(INT HUP TERM TSTP QUIT USR1 USR2)} = ($h1) x 7;
my $err;
eval { # die must be caught, otherwise we end up with two running daemons
local(@SIG{qw(INT HUP TERM TSTP QUIT USR1 USR2)}) = ($h2) x 7;
if ($interrupt ne '') { my $i = $interrupt; $interrupt = ''; die $i }
close STDIN; # ignoring errors
close STDOUT; # ignoring errors
# BEWARE of Perl older that 5.6.0: sockets and pipes were not FD_CLOEXEC
exec {$cmd} ($cmd,@args);
die "spawn_command: failed to exec $cmd_text: $!";
0; # paranoia
} or do {
$err = $@ ne '' ? $@ : "errno=$!"; chomp $err;
};
eval {
local(@SIG{qw(INT HUP TERM TSTP QUIT USR1 USR2)}) = ($h2) x 7;
if ($interrupt ne '') { my $i = $interrupt; $interrupt = ''; die $i }
# we're in trouble if stderr was attached to a terminal, but no longer is
eval { do_log(-1,"spawn_command: child process [%s]: %s", $$,$err) };
} or 1; # ignore failures, make perlcritic happy
{ # no warnings;
POSIX::_exit(6); # avoid END and destructor processing
kill('KILL',$$); exit 1; # still kicking? die!
}
}
# parent
do_log(5,"spawn_command: [%s] %s", $pid, $cmd_text);
$pid; # return the PID of a subprocess
}
sub usage() {
my $me = $0; local $1; $me =~ s{([^/]*)\z}{$1}s;
"Usage: $me (-h | -V | [-f] [-P pid_file] [-d log_level])";
}
# map process termination status number to an informative string, and
# append optional message (dual-valued errno or a string or a number),
# returning the resulting string
#
sub exit_status_str($;$) {
my($stat,$errno) = @_; my $str;
if (!defined($stat)) {
$str = '(no status)';
} elsif (WIFEXITED($stat)) {
$str = sprintf('exit %d', WEXITSTATUS($stat));
} elsif (WIFSTOPPED($stat)) {
$str = sprintf('stopped, signal %d', WSTOPSIG($stat));
} else {
my $sig = WTERMSIG($stat);
$str = sprintf('%s, signal %d (%04x)',
$sig == 1 ? 'HANGUP' : $sig == 2 ? 'INTERRUPTED' :
$sig == 6 ? 'ABORTED' : $sig == 9 ? 'KILLED' :
$sig == 15 ? 'TERMINATED' : 'DIED',
$sig, $stat);
}
if (defined $errno) { # deal with dual-valued and plain variables
$str .= ', '.$errno if (0+$errno) != 0 || ($errno ne '' && $errno ne '0');
}
$str;
}
# check errno to be 0 and a process exit status to be in the list of success
# status codes, returning true if both are ok, and false otherwise
#
sub proc_status_ok($;$@) {
my($exit_status,$errno,@success) = @_;
my $ok = 0;
if ((!defined $errno || $errno == 0) && WIFEXITED($exit_status)) {
my $j = WEXITSTATUS($exit_status);
if (!@success) { $ok = $j==0 } # empty list implies only status 0 is good
elsif (grep($_==$j, @success)) { $ok = 1 }
}
$ok;
}
sub report_terminations($) {
my($pids_exited_list) = @_;
# note: child_handler may be growing the list at its tail during the loop
while (@$pids_exited_list) {
my $pid_stat = shift(@$pids_exited_list);
next if !$pid_stat; # just in case
my($pid,$status,$timestamp) = @$pid_stat;
my $serv = delete $pid2service{$pid};
if (!$serv) {
do_log(-1,'Unknown process [%d] exited: %s',
$pid, exit_status_str($status,0));
} else {
$serv->{status} = $status;
$serv->{terminated_at} = $timestamp;
my $ll = proc_status_ok($status,0) ? 0 : -1;
do_log($ll, 'Process [%d] exited (%s) after %.1f s: %s',
$pid, $serv->{cmd},
$serv->{terminated_at} - $serv->{started_at},
exit_status_str($status,0));
}
}
}
sub child_handler {
my $signal = $_[0];
for (;;) {
my $child_pid = waitpid(-1,WNOHANG);
# PID may be negative on Windows
last if !$child_pid || $child_pid == -1;
push(@pids_exited, [$child_pid, $?, time]);
}
$SIG{CHLD} = \&child_handler;
};
# main program starts here
delete @ENV{'PATH', 'IFS', 'CDPATH', 'ENV', 'BASH_ENV'};
$ENV{PATH} = join(':',@path) if @path;
my $foreground = 0;
my(@argv) = @ARGV; # preserve @ARGV, may modify @argv
while (@argv >= 2 && $argv[0] =~ /^-[dP]\z/ ||
@argv >= 1 && $argv[0] =~ /^-/) {
my($opt,$val);
$opt = shift @argv;
$val = shift @argv if $opt !~ /^-[hVf-]\z/; # these take no arguments
if ($opt eq '--') {
last;
} elsif ($opt eq '-h') { # -h (help)
die "$myversion\n\n" . usage() . "\n";
} elsif ($opt eq '-V') { # -V (version)
die "$myversion\n";
} elsif ($opt eq '-f') {
$foreground = 1;
} elsif ($opt eq '-d') { # -d log_level
$val =~ /^\d+\z/ or die "Bad value for option -d: $val\n";
$log_level = untaint($val);
} elsif ($opt eq '-P') { # -P pid_file
$pid_file = untaint($val);
} else {
die "Error in command line options: $opt\n\n" . usage() . "\n";
}
}
!@argv or die sprintf("Error parsing a command line %s\n\n%s\n",
join(' ',@ARGV), usage());
$SIG{'__DIE__' } =
sub { if (!$^S) { my($m) = @_; chomp($m); do_log(-1,"_DIE: %s", $m) } };
$SIG{'__WARN__'} =
sub { my($m) = @_; chomp($m); do_log(0,"_WARN: %s",$m) };
if ($foreground) {
do_log(0,"amavis master process starting in foreground, perl %s", $] );
} else { # daemonize
openlog($syslog_ident, LOG_PID | LOG_NDELAY, $syslog_facility);
$syslog_open = 1;
do_log(2,"to be daemonized");
daemonize();
srand();
do_log(0,'amavis master process starting. '.
'daemonized as PID [%s], perl %s', $$, $] );
}
if (defined $daemon_user) {
drop_priv($daemon_user,$daemon_group);
}
if (defined $pid_file && $pid_file ne '') {
my $pid_file_fh = IO::File->new;
$pid_file_fh->open($pid_file, O_CREAT|O_WRONLY, 0640)
or die "Can't create PID file $pid_file: $!";
$pid_file_fh->print($$."\n")
or die "Can't write to PID file $pid_file: $!";
$pid_file_fh->close
or die "Can't close PID file $pid_file: $!";
$pid_file_created = 1;
}
# initialize
for my $serv (@services) {
$serv->{started_cnt} = 0;
$serv->{pid} = $serv->{status} = undef;
$serv->{started_at} = $serv->{terminated_at} = undef;
my $found = find_program_path($serv->{cmd}, \@path);
defined $found
or die sprintf("Can't find program %s in path %s\n",
$serv->{cmd}, join(':',@path));
$serv->{cmd} = $found;
}
$SIG{CHLD} = \&child_handler;
eval { # catch TERM and INT signals for a controlled shutdown
my $h = sub { $interrupted = $_[0]; die "\n" };
local $SIG{INT} = $h;
local $SIG{TERM} = $h;
for (;;) {
last if defined $interrupted;
for my $serv (@services) {
next if $serv->{disabled};
report_terminations(\@pids_exited) if @pids_exited;
if (defined $serv->{status}) {
# process has terminated, clean up
$serv->{pid} = undef;
$serv->{started_at} = undef;
}
last if defined $interrupted;
if (!defined $serv->{pid}) {
# service not running
if ($serv->{started_cnt} >= 5) {
do_log(-1,'Exceeded restart count, giving up on (%s)', $serv->{cmd});
$serv->{disabled} = 1;
} elsif (defined $serv->{terminated_at} &&
time - $serv->{terminated_at} < 1) {
# postpone a restart for at least a second
do_log(5, 'Postponing a restart (%s)', $serv->{cmd});
} else {
my($cmd,@args) = split(' ',$serv->{cmd});
$serv->{started_cnt}++;
$serv->{status} = $serv->{terminated_at} = undef;
$serv->{started_at} = time;
my $pid = $serv->{pid} = spawn_command($cmd,@args);
do_log(0, 'Process [%d] started: %s', $pid, $serv->{cmd});
# to avoid race the signal handler must not be updating %pid2service
$pid2service{$pid} = $serv;
}
}
}
sleep 5; # sleep may be aborted prematurely by a signal
} # until interrupted
};
do_log(0, 'Master process shutting down');
for my $sig ('TERM', 'KILL') {
# terminate or kill child processes
for my $serv (@services) {
my $pid = $serv->{pid};
next if !$pid;
my $n = kill($sig,$pid);
if ($n == 0 && $! == ESRCH) {
# process already gone
} elsif ($n == 0) {
do_log(-1, "Can't send SIG%s to process [%s]: %s", $sig, $pid, $!);
} else {
do_log(0, "%s process [%s] (%s)",
$sig eq 'TERM' ? 'Terminating' : 'Killing',
$pid, $serv->{cmd});
}
}
my $deadline = time + 10; # 10 second grace period
while (time < $deadline) {
report_terminations(\@pids_exited);
sleep 1; # sleep may be aborted prematurely by a signal
# stop waiting if all gone
last if !grep { $_->{pid} && kill(0, $_->{pid}) } @services;
}
report_terminations(\@pids_exited);
}
END {
do_log(0,'Master process exiting: %s', $interrupted) if defined $interrupted;
if ($pid_file_created) {
unlink($pid_file)
or do_log(-1, "Can't delete a PID file %s: %s", $pid_file, $!);
}
if ($syslog_open) { closelog(); $syslog_open = 0 }
}
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