clamav/clamav-milter/clamav-milter.c

/*
 *  Copyright (C) 2013-2021 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *  Copyright (C) 2008-2013 Sourcefire, Inc.
 *
 *  Author: aCaB <acab@clamav.net>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA 02110-1301, USA.
 */

#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>
#include <signal.h>
#include <pthread.h>
#ifdef USE_SYSLOG
#include <syslog.h>
#endif
#include <time.h>
#include <libmilter/mfapi.h>

// libclamav
#include "clamav.h"
#include "default.h"

// common
#include "output.h"
#include "optparser.h"
#include "misc.h"

#include "connpool.h"
#include "netcode.h"
#include "clamfi.h"
#include "allow_list.h"

#ifndef _WIN32
#include <sys/wait.h>
#endif

struct smfiDesc descr;
struct optstruct *opts;

static void milter_exit(int sig)
{
    const struct optstruct *opt;

    logg("*clamav-milter: milter_exit, signal %d\n", sig);

#ifndef _WIN32
    if ((opt = optget(opts, "MilterSocket"))) {
        if (unlink(opt->strarg) == -1)
            logg("!Can't unlink the socket file %s\n", opt->strarg);
        else
            logg("Socket file removed.\n");
    }
#endif

    logg("clamav-milter: stopped\n");

    optfree(opts);

    logg_close();
    cpool_free();
    localnets_free();
    allow_list_free();
}

int main(int argc, char **argv)
{
    char *my_socket, *pt;
    const struct optstruct *opt;
    time_t currtime;
    mode_t umsk;
    pid_t parentPid = getpid();
#ifndef _WIN32
    int dropPrivRet = 0;
#endif /* _WIN32 */

    sigset_t sigset;
    struct sigaction act;
    const char *user_name = NULL;

    cl_initialize_crypto();

    memset(&descr, 0, sizeof(struct smfiDesc));
    descr.xxfi_name    = "ClamAV";         /* filter name */
    descr.xxfi_version = SMFI_VERSION;     /* milter version */
    descr.xxfi_flags   = SMFIF_QUARANTINE; /* flags */
    descr.xxfi_connect = clamfi_connect;   /* connection info filter */
    descr.xxfi_envfrom = clamfi_envfrom;   /* envelope sender filter */
    descr.xxfi_envrcpt = clamfi_envrcpt;   /* envelope recipient filter */
    descr.xxfi_header  = clamfi_header;    /* header filter */
    descr.xxfi_body    = clamfi_body;      /* body block */
    descr.xxfi_eom     = clamfi_eom;       /* end of message */
    descr.xxfi_abort   = clamfi_abort;     /* message aborted */

    opts = optparse(NULL, argc, argv, 1, OPT_MILTER, 0, NULL);
    if (!opts) {
        mprintf("!Can't parse command line options\n");
        return 1;
    }

    if (optget(opts, "help")->enabled) {
        printf("\n");
        printf("                       Clam AntiVirus: Milter Mail Scanner %s\n", get_version());
        printf("           By The ClamAV Team: https://www.clamav.net/about.html#credits\n");
        printf("           (C) 2021 Cisco Systems, Inc.\n");
        printf("\n");
        printf("    %s [-c <config-file>]\n\n", argv[0]);
        printf("\n");
        printf("    --help                   -h       Show this help\n");
        printf("    --version                -V       Show version\n");
        printf("    --config-file <file>     -c       Read configuration from file\n");
        printf("\n");
        optfree(opts);
        return 0;
    }

    if (opts->filename) {
        int x;
        for (x = 0; opts->filename[x]; x++)
            mprintf("^Ignoring option %s\n", opts->filename[x]);
    }

    if (optget(opts, "version")->enabled) {
        printf("clamav-milter %s\n", get_version());
        optfree(opts);
        return 0;
    }

    pt = strdup(optget(opts, "config-file")->strarg);
    if (pt == NULL) {
        printf("Unable to allocate memory for config file\n");
        return 1;
    }
    if ((opts = optparse(pt, 0, NULL, 1, OPT_MILTER, 0, opts)) == NULL) {
        printf("%s: cannot parse config file %s\n", argv[0], pt);
        free(pt);
        return 1;
    }
    free(pt);

    if ((opt = optget(opts, "User"))->enabled) {
        user_name = opt->strarg;
    }

    if ((opt = optget(opts, "Chroot"))->enabled) {
        if (chdir(opt->strarg) != 0) {
            logg("!Cannot change directory to %s\n", opt->strarg);
            return 1;
        }
        if (chroot(opt->strarg) != 0) {
            logg("!chroot to %s failed. Are you root?\n", opt->strarg);
            return 1;
        }
    }

    pt = optget(opts, "AddHeader")->strarg;
    if (strcasecmp(pt, "No")) {
        char myname[255];

        if (((opt = optget(opts, "ReportHostname"))->enabled &&
             strncpy(myname, opt->strarg, sizeof(myname))) ||
            !gethostname(myname, sizeof(myname))) {

            myname[sizeof(myname) - 1] = '\0';
            snprintf(xvirushdr, sizeof(xvirushdr), "clamav-milter %s at %s",
                     get_version(), myname);
        } else {
            snprintf(xvirushdr, sizeof(xvirushdr), "clamav-milter %s",
                     get_version());
        }
        xvirushdr[sizeof(xvirushdr) - 1] = '\0';

        descr.xxfi_flags |= SMFIF_ADDHDRS;

        if (strcasecmp(pt, "Add")) { /* Replace or Yes */
            descr.xxfi_flags |= SMFIF_CHGHDRS;
            addxvirus = 1;
        } else { /* Add */
            addxvirus = 2;
        }
    }

    if (!(my_socket = optget(opts, "MilterSocket")->strarg)) {
        logg("!Please configure the MilterSocket directive\n");
        logg_close();
        optfree(opts);
        return 1;
    }

    if (smfi_setconn(my_socket) == MI_FAILURE) {
        logg("!smfi_setconn failed\n");
        logg_close();
        optfree(opts);
        return 1;
    }
    if (smfi_register(descr) == MI_FAILURE) {
        logg("!smfi_register failed\n");
        logg_close();
        optfree(opts);
        return 1;
    }
    opt  = optget(opts, "FixStaleSocket");
    umsk = umask(0777); /* socket is created with 000 to avoid races */
    if (smfi_opensocket(opt->enabled) == MI_FAILURE) {
        logg("!Failed to create socket %s\n", my_socket);
        logg_close();
        optfree(opts);
        return 1;
    }
    umask(umsk); /* restore umask */
    if (strncmp(my_socket, "inet:", 5) && strncmp(my_socket, "inet6:", 6)) {
        /* set group ownership and perms on the local socket */
        char *sock_name = my_socket;
        mode_t sock_mode;
        if (!strncmp(my_socket, "unix:", 5))
            sock_name += 5;
        if (!strncmp(my_socket, "local:", 6))
            sock_name += 6;
        if (*my_socket == ':')
            sock_name++;

        if (optget(opts, "MilterSocketGroup")->enabled) {
            char *gname    = optget(opts, "MilterSocketGroup")->strarg, *end;
            gid_t sock_gid = strtol(gname, &end, 10);
            if (*end) {
                struct group *pgrp = getgrnam(gname);
                if (!pgrp) {
                    logg("!Unknown group %s\n", gname);
                    logg_close();
                    optfree(opts);
                    return 1;
                }
                sock_gid = pgrp->gr_gid;
            }
            if (chown(sock_name, -1, sock_gid)) {
                logg("!Failed to change socket ownership to group %s\n", gname);
                logg_close();
                optfree(opts);
                return 1;
            }
        }

        if (NULL != user_name) {
            struct passwd *user;
            if ((user = getpwnam(user_name)) == NULL) {
                logg("ERROR: Can't get information about user %s.\n",
                     user_name);
                logg_close();
                optfree(opts);
                return 1;
            }

            if (chown(sock_name, user->pw_uid, -1)) {
                logg("!Failed to change socket ownership to user %s\n", user->pw_name);
                optfree(opts);
                logg_close();
                return 1;
            }
        }

        if (optget(opts, "MilterSocketMode")->enabled) {
            char *end;
            sock_mode = strtol(optget(opts, "MilterSocketMode")->strarg, &end, 8);
            if (*end) {
                logg("!Invalid MilterSocketMode %s\n", optget(opts, "MilterSocketMode")->strarg);
                logg_close();
                optfree(opts);
                return 1;
            }
        } else
            sock_mode = 0777 & ~umsk;

        if (chmod(sock_name, sock_mode & 0666)) {
            logg("!Cannot set milter socket permission to %s\n", optget(opts, "MilterSocketMode")->strarg);
            logg_close();
            optfree(opts);
            return 1;
        }
    }

    logg_lock    = !optget(opts, "LogFileUnlock")->enabled;
    logg_time    = optget(opts, "LogTime")->enabled;
    logg_size    = optget(opts, "LogFileMaxSize")->numarg;
    logg_verbose = mprintf_verbose = optget(opts, "LogVerbose")->enabled;
    if (logg_size)
        logg_rotate = optget(opts, "LogRotate")->enabled;

    if ((opt = optget(opts, "LogFile"))->enabled) {
        logg_file = opt->strarg;
        if (!cli_is_abspath(logg_file)) {
            fprintf(stderr, "ERROR: LogFile requires full path.\n");
            logg_close();
            optfree(opts);
            return 1;
        }
    } else
        logg_file = NULL;

#if defined(USE_SYSLOG) && !defined(C_AIX)
    if (optget(opts, "LogSyslog")->enabled) {
        int fac;

        opt = optget(opts, "LogFacility");
        if ((fac = logg_facility(opt->strarg)) == -1) {
            logg("!LogFacility: %s: No such facility.\n", opt->strarg);
            logg_close();
            optfree(opts);
            return 1;
        }

        openlog("clamav-milter", LOG_PID, fac);
        logg_syslog = 1;
    }
#endif

    time(&currtime);
    if (logg("#+++ Started at %s", ctime(&currtime))) {
        fprintf(stderr, "ERROR: Can't initialize the internal logger\n");
        logg_close();
        optfree(opts);
        return 1;
    }
    if ((opt = optget(opts, "TemporaryDirectory"))->enabled)
        tempdir = opt->strarg;

    if (localnets_init(opts) || init_actions(opts)) {
        logg_close();
        optfree(opts);
        return 1;
    }

    if (((opt = optget(opts, "Whitelist"))->enabled || (opt = optget(opts, "AllowList"))->enabled) && allow_list_init(opt->strarg)) {
        localnets_free();
        logg_close();
        optfree(opts);
        return 1;
    }

    if ((opt = optget(opts, "SkipAuthenticated"))->enabled && smtpauth_init(opt->strarg)) {
        localnets_free();
        allow_list_free();
        logg_close();
        optfree(opts);
        return 1;
    }

    multircpt = optget(opts, "SupportMultipleRecipients")->enabled;

#ifndef _WIN32
    if (!optget(opts, "Foreground")->enabled) {
        if (-1 == daemonize_parent_wait(user_name, logg_file)) {
            logg("!daemonize() failed\n");
            localnets_free();
            allow_list_free();
            cpool_free();
            logg_close();
            optfree(opts);
            return 1;
        }
        if (chdir("/") == -1) {
            logg("^Can't change current working directory to root\n");
        }
    }

    sigfillset(&sigset);
    sigdelset(&sigset, SIGUSR1);
    sigdelset(&sigset, SIGFPE);
    sigdelset(&sigset, SIGILL);
    sigdelset(&sigset, SIGSEGV);
#ifdef SIGBUS
    sigdelset(&sigset, SIGBUS);
#endif
    pthread_sigmask(SIG_SETMASK, &sigset, NULL);
    memset(&act, 0, sizeof(struct sigaction));
    act.sa_handler = milter_exit;
    sigfillset(&(act.sa_mask));
    sigaction(SIGUSR1, &act, NULL);
    sigaction(SIGSEGV, &act, NULL);

#endif /* _WIN32 */

    maxfilesize = optget(opts, "MaxFileSize")->numarg;
    if (!maxfilesize) {
        logg("^Invalid MaxFileSize, using default (%d)\n", CLI_DEFAULT_MAXFILESIZE);
        maxfilesize = CLI_DEFAULT_MAXFILESIZE;
    }
    readtimeout = optget(opts, "ReadTimeout")->numarg;

    cpool_init(opts);
    if (!cp) {
        logg("!Failed to init the socket pool\n");
        localnets_free();
        allow_list_free();
        logg_close();
        optfree(opts);
        return 1;
    }

    if ((opt = optget(opts, "PidFile"))->enabled) {
        FILE *fd;
        mode_t old_umask = umask(0022);
        int err          = 0;

        if ((fd = fopen(opt->strarg, "w")) == NULL) {
            logg("!Can't save PID in file %s\n", opt->strarg);
            err = 1;
        } else {
            if (fprintf(fd, "%u\n", (unsigned int)getpid()) < 0) {
                logg("!Can't save PID in file %s\n", opt->strarg);
                err = 1;
            }
            fclose(fd);
        }
        umask(old_umask);

#ifndef _WIN32
        if (0 == err) {
            /*If the file has already been created by a different user, it will just be
             * rewritten by us, but not change the ownership, so do that explicitly.
             */
            if (0 == geteuid()) {
                struct passwd *pw = getpwuid(0);
                int ret           = lchown(opt->strarg, pw->pw_uid, pw->pw_gid);
                if (ret) {
                    logg("!Can't change ownership of PID file %s '%s'\n", opt->strarg, strerror(errno));
                    err = 1;
                }
            }
        }
#endif /*_WIN32*/

        if (err) {
            localnets_free();
            allow_list_free();
            logg_close();
            optfree(opts);
            return 2;
        }
    }

#ifndef _WIN32
    dropPrivRet = drop_privileges(user_name, logg_file);
    if (dropPrivRet) {
        optfree(opts);
        return dropPrivRet;
    }

    /* We have been daemonized, and initialization is done.  Signal
     * the parent process so that it can exit cleanly.
     */
    if (parentPid != getpid()) { //we have been daemonized
        daemonize_signal_parent(parentPid);
    }
#endif

    return smfi_main();
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * tab-width: 8
 * End:
 * vim: set cindent smartindent autoindent softtabstop=4 shiftwidth=4 tabstop=8:
 */