clamav/clamd/scanner.c

/*
 *  Copyright (C) 2013-2021 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *  Copyright (C) 2007-2013 Sourcefire, Inc.
 *
 *  Authors: Tomasz Kojm, Török Edvin
 *
 *  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 <stdlib.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
#ifndef _WIN32
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/param.h>
#include <signal.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#endif
#include <pthread.h>

// libclamav
#include "clamav.h"
#include "others.h"
#include "scanners.h"

// shared
#include "idmef_logging.h"
#include "optparser.h"
#include "output.h"
#include "misc.h"

#include "clamd_others.h"
#include "scanner.h"
#include "shared.h"
#include "thrmgr.h"
#include "server.h"

#ifdef C_LINUX
dev_t procdev; /* /proc device */
#endif

extern int progexit;
extern time_t reloaded_time;
extern pthread_mutex_t reload_mutex;

void msg_callback(enum cl_msg severity, const char *fullmsg, const char *msg, void *ctx)
{
    struct cb_context *c = ctx;
    const char *filename = (c && c->filename) ? c->filename : "";

    UNUSEDPARAM(fullmsg);

    switch (severity) {
        case CL_MSG_ERROR:
            logg("^[LibClamAV] %s: %s", filename, msg);
            break;
        case CL_MSG_WARN:
            logg("~[LibClamAV] %s: %s", filename, msg);
            break;
        case CL_MSG_INFO_VERBOSE:
            logg("*[LibClamAV] %s: %s", filename, msg);
            break;
        default:
            logg("$[LibClamAV] %s: %s", filename, msg);
            break;
    }
}

void hash_callback(int fd, unsigned long long size, const unsigned char *md5, const char *virname, void *ctx)
{
    struct cb_context *c = ctx;
    UNUSEDPARAM(fd);
    UNUSEDPARAM(virname);

    if (!c)
        return;
    c->virsize = size;
    strncpy(c->virhash, (const char *)md5, 32);
    c->virhash[32] = '\0';
}

void clamd_virus_found_cb(int fd, const char *virname, void *ctx)
{
    struct cb_context *c   = ctx;
    struct scan_cb_data *d = c->scandata;
    const char *fname;

    UNUSEDPARAM(fd);

    if (d == NULL)
        return;
    if (!(d->options->general & CL_SCAN_GENERAL_ALLMATCHES) && !(d->options->general & CL_SCAN_GENERAL_HEURISTIC_PRECEDENCE))
        return;
    if (virname == NULL)
        return;

    fname = (c && c->filename) ? c->filename : "(filename not set)";

    if (virname) {
        d->infected++;
        conn_reply_virus(d->conn, fname, virname);
        if (c->virsize > 0 && optget(d->opts, "ExtendedDetectionInfo")->enabled)
            logg("~%s: %s(%s:%llu) FOUND\n", fname, virname, c->virhash, c->virsize);
        logg("~%s: %s FOUND\n", fname, virname);
    }

    return;
}

#define BUFFSIZE 1024
cl_error_t scan_callback(STATBUF *sb, char *filename, const char *msg, enum cli_ftw_reason reason, struct cli_ftw_cbdata *data)
{
    struct scan_cb_data *scandata = data->data;
    const char *virname           = NULL;
    int ret;
    int type = scandata->type;
    struct cb_context context;
    char *real_filename = NULL;

    if (NULL != filename) {
        if (CL_SUCCESS != cli_realpath((const char *)filename, &real_filename)) {
            conn_reply_errno(scandata->conn, msg, "Failed to determine real path:");
            logg("^Failed to determine real path for: %s\n", filename);
            logg("*Quarantine of the file may fail if file path contains symlinks.\n");
        } else {
            free(filename);
            filename = real_filename;
        }
    }

    /* detect disconnected socket,
     * this should NOT detect half-shutdown sockets (SHUT_WR) */
    if (send(scandata->conn->sd, &ret, 0, 0) == -1 && errno != EINTR) {
        logg("$Client disconnected while command was active!\n");
        thrmgr_group_terminate(scandata->conn->group);
        if (reason == visit_file)
            free(filename);
        return CL_BREAK;
    }

    if (thrmgr_group_need_terminate(scandata->conn->group)) {
        logg("^Client disconnected while scanjob was active\n");
        if (reason == visit_file)
            free(filename);
        return CL_BREAK;
    }
    scandata->total++;
    switch (reason) {
        case error_mem:
            if (msg)
                logg("!Memory allocation failed during cli_ftw() on %s\n",
                     msg);
            else
                logg("!Memory allocation failed during cli_ftw()\n");
            scandata->errors++;
            return CL_EMEM;
        case error_stat:
            conn_reply_errno(scandata->conn, msg, "lstat() failed:");
            logg("^lstat() failed on: %s\n", msg);
            scandata->errors++;
            return CL_SUCCESS;
        case warning_skipped_dir:
            logg("^Directory recursion limit reached, skipping %s\n",
                 msg);
            return CL_SUCCESS;
        case warning_skipped_link:
            logg("$Skipping symlink: %s\n", msg);
            return CL_SUCCESS;
        case warning_skipped_special:
            if (msg == scandata->toplevel_path)
                conn_reply(scandata->conn, msg, "Not supported file type", "ERROR");
            logg("*Not supported file type: %s\n", msg);
            return CL_SUCCESS;
        case visit_directory_toplev:
            return CL_SUCCESS;
        case visit_file:
            break;
    }

#ifdef C_LINUX
    /* check whether the file is excluded */
    if (procdev && sb && (sb->st_dev == procdev)) {
        free(filename);
        return CL_SUCCESS;
    }
#endif

    if (sb && sb->st_size == 0) { /* empty file */
        if (msg == scandata->toplevel_path)
            conn_reply_single(scandata->conn, filename, "Empty file");
        free(filename);
        return CL_SUCCESS;
    }

    if (type == TYPE_MULTISCAN) {
        client_conn_t *client_conn = (client_conn_t *)calloc(1, sizeof(struct client_conn_tag));
        if (client_conn) {
            client_conn->scanfd   = -1;
            client_conn->sd       = scandata->odesc;
            client_conn->filename = filename;
            client_conn->cmdtype  = COMMAND_MULTISCANFILE;
            client_conn->term     = scandata->conn->term;
            client_conn->options  = scandata->options;
            client_conn->opts     = scandata->opts;
            client_conn->group    = scandata->group;
            if (cl_engine_addref(scandata->engine)) {
                logg("!cl_engine_addref() failed\n");
                free(filename);
                free(client_conn);
                return CL_EMEM;
            } else {
                client_conn->engine = scandata->engine;
                pthread_mutex_lock(&reload_mutex);
                client_conn->engine_timestamp = reloaded_time;
                pthread_mutex_unlock(&reload_mutex);
                if (!thrmgr_group_dispatch(scandata->thr_pool, scandata->group, client_conn, 1)) {
                    logg("!thread dispatch failed\n");
                    cl_engine_free(scandata->engine);
                    free(filename);
                    free(client_conn);
                    return CL_EMEM;
                }
            }
        } else {
            logg("!Can't allocate memory for client_conn\n");
            scandata->errors++;
            free(filename);
            return CL_EMEM;
        }
        return CL_SUCCESS;
    }

    thrmgr_setactivetask(filename, NULL);
    context.filename = filename;
    context.virsize  = 0;
    context.scandata = scandata;
    ret              = cl_scanfile_callback(filename, &virname, &scandata->scanned, scandata->engine, scandata->options, &context);
    thrmgr_setactivetask(NULL, NULL);

    if (thrmgr_group_need_terminate(scandata->conn->group)) {
        free(filename);
        logg("*Client disconnected while scanjob was active\n");
        return ret == CL_ETIMEOUT ? ret : CL_BREAK;
    }

    if ((ret == CL_VIRUS) && (virname == NULL)) {
        logg("*%s: reported CL_VIRUS but no virname returned!\n", filename);
        ret = CL_EMEM;
    }

    if (ret == CL_EACCES) {
        if (conn_reply(scandata->conn, filename, "Access denied.", "ERROR") == -1) {
            free(filename);
            return CL_ETIMEOUT;
        }
        logg("*Access denied: %s\n", filename);
        scandata->errors++;
        free(filename);
        return CL_SUCCESS;
    }

    if (ret == CL_VIRUS) {

        if (scandata->options->general & CL_SCAN_GENERAL_ALLMATCHES || (scandata->infected && scandata->options->general & CL_SCAN_GENERAL_HEURISTIC_PRECEDENCE)) {
            if (optget(scandata->opts, "PreludeEnable")->enabled) {
                prelude_logging(filename, virname, context.virhash, context.virsize);
            }
            virusaction(filename, virname, scandata->opts);
        } else {
            scandata->infected++;
            if (conn_reply_virus(scandata->conn, filename, virname) == -1) {
                free(filename);
                return CL_ETIMEOUT;
            }
            if (optget(scandata->opts, "PreludeEnable")->enabled) {
                prelude_logging(filename, virname, context.virhash, context.virsize);
            }

            if (context.virsize && optget(scandata->opts, "ExtendedDetectionInfo")->enabled)
                logg("~%s: %s(%s:%llu) FOUND\n", filename, virname, context.virhash, context.virsize);
            else
                logg("~%s: %s FOUND\n", filename, virname);
            virusaction(filename, virname, scandata->opts);
        }
    } else if (ret != CL_CLEAN) {
        scandata->errors++;
        if (conn_reply(scandata->conn, filename, cl_strerror(ret), "ERROR") == -1) {
            free(filename);
            return CL_ETIMEOUT;
        }
        logg("~%s: %s ERROR\n", filename, cl_strerror(ret));
    } else if (logok) {
        logg("~%s: OK\n", filename);
    }

    free(filename);

    if (ret == CL_EMEM) /* stop scanning */
        return ret;

    if (type == TYPE_SCAN) {
        /* virus -> break */
        return ret;
    }

    /* keep scanning always */
    return CL_SUCCESS;
}

int scan_pathchk(const char *path, struct cli_ftw_cbdata *data)
{
    struct scan_cb_data *scandata = data->data;
    const struct optstruct *opt;
    STATBUF statbuf;

    if ((opt = optget(scandata->opts, "ExcludePath"))->enabled) {
        while (opt) {
            if (match_regex(path, opt->strarg) == 1) {
                if (scandata->type != TYPE_MULTISCAN)
                    conn_reply_single(scandata->conn, path, "Excluded");
                return 1;
            }
            opt = (const struct optstruct *)opt->nextarg;
        }
    }

    if (!optget(scandata->opts, "CrossFilesystems")->enabled) {
        if (CLAMSTAT(path, &statbuf) == 0) {
            if (statbuf.st_dev != scandata->dev) {
                if (scandata->type != TYPE_MULTISCAN)
                    conn_reply_single(scandata->conn, path, "Excluded (another filesystem)");
                return 1;
            }
        }
    }

    return 0;
}

cl_error_t scanfd(
    const client_conn_t *conn,
    unsigned long int *scanned,
    const struct cl_engine *engine,
    struct cl_scan_options *options,
    const struct optstruct *opts,
    int odesc,
    int stream)
{
    cl_error_t ret      = -1;
    int fd              = conn->scanfd;
    const char *virname = NULL;
    STATBUF statbuf;
    struct cb_context context;
    char fdstr[32];
    const char *reply_fdstr;

    char *filepath     = NULL;
    char *log_filename = fdstr;

    UNUSEDPARAM(odesc);

    if (stream) {
        struct sockaddr_in sa;
        socklen_t salen = sizeof(sa);
        if (getpeername(conn->sd, (struct sockaddr *)&sa, &salen) || salen > sizeof(sa) || sa.sin_family != AF_INET)
            strncpy(fdstr, "instream(local)", sizeof(fdstr));
        else
            snprintf(fdstr, sizeof(fdstr), "instream(%s@%u)", inet_ntoa(sa.sin_addr), ntohs(sa.sin_port));
        reply_fdstr = "stream";
    } else {
        snprintf(fdstr, sizeof(fdstr), "fd[%d]", fd);
        reply_fdstr = fdstr;
    }
    if (FSTAT(fd, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
        logg("%s: Not a regular file. ERROR\n", fdstr);
        if (conn_reply(conn, reply_fdstr, "Not a regular file", "ERROR") == -1) {
            ret = CL_ETIMEOUT;
            goto done;
        }
        ret = CL_BREAK;
        goto done;
    }

    /* Try and get the real filename, for logging purposes */
    if (!stream) {
        if (CL_SUCCESS != cli_get_filepath_from_filedesc(fd, &filepath)) {
            logg("*%s: Unable to determine the filepath given the file descriptor.\n", fdstr);
        } else {
            log_filename = filepath;
        }
    }

    thrmgr_setactivetask(fdstr, NULL);
    context.filename = fdstr;
    context.virsize  = 0;
    context.scandata = NULL;
    ret              = cl_scandesc_callback(fd, log_filename, &virname, scanned, engine, options, &context);
    thrmgr_setactivetask(NULL, NULL);

    if (thrmgr_group_need_terminate(conn->group)) {
        logg("*Client disconnected while scanjob was active\n");
        ret = ret == CL_ETIMEOUT ? ret : CL_BREAK;
        goto done;
    }

    if (ret == CL_VIRUS) {
        if (conn_reply_virus(conn, reply_fdstr, virname) == -1)
            ret = CL_ETIMEOUT;
        if (context.virsize && optget(opts, "ExtendedDetectionInfo")->enabled)
            logg("%s: %s(%s:%llu) FOUND\n", log_filename, virname, context.virhash, context.virsize);
        else
            logg("%s: %s FOUND\n", log_filename, virname);
        virusaction(log_filename, virname, opts);
    } else if (ret != CL_CLEAN) {
        if (conn_reply(conn, reply_fdstr, cl_strerror(ret), "ERROR") == -1)
            ret = CL_ETIMEOUT;
        logg("%s: %s ERROR\n", log_filename, cl_strerror(ret));
    } else {
        if (conn_reply_single(conn, reply_fdstr, "OK") == CL_ETIMEOUT)
            ret = CL_ETIMEOUT;
        if (logok)
            logg("%s: OK\n", log_filename);
    }

done:
    if (NULL != filepath) {
        free(filepath);
    }

    return ret;
}

int scanstream(
    int odesc,
    unsigned long int *scanned,
    const struct cl_engine *engine,
    struct cl_scan_options *options,
    const struct optstruct *opts,
    char term)
{
    int ret, sockfd, acceptd;
    int tmpd, bread, retval, firsttimeout, timeout, btread;
    unsigned int port       = 0, portscan, min_port, max_port;
    unsigned long int quota = 0, maxsize = 0;
    short bound         = 0;
    const char *virname = NULL;
    char buff[FILEBUFF];
    char peer_addr[32];
    struct cb_context context;
    struct sockaddr_in server;
    struct sockaddr_in peer;
    socklen_t addrlen;
    char *tmpname;

    min_port = optget(opts, "StreamMinPort")->numarg;
    max_port = optget(opts, "StreamMaxPort")->numarg;

    /* search for a free port to bind to */
    port  = cli_rndnum(max_port - min_port);
    bound = 0;
    for (portscan = 0; portscan < 1000; portscan++) {
        port = (port - 1) % (max_port - min_port + 1);

        memset((char *)&server, 0, sizeof(server));
        server.sin_family      = AF_INET;
        server.sin_port        = htons(min_port + port);
        server.sin_addr.s_addr = htonl(INADDR_ANY);

        if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
            continue;

        if (bind(sockfd, (struct sockaddr *)&server, (socklen_t)sizeof(struct sockaddr_in)) == -1)
            closesocket(sockfd);
        else {
            bound = 1;
            break;
        }
    }
    port += min_port;

    timeout      = optget(opts, "ReadTimeout")->numarg;
    firsttimeout = optget(opts, "CommandReadTimeout")->numarg;

    if (!bound) {
        logg("!ScanStream: Can't find any free port.\n");
        mdprintf(odesc, "Can't find any free port. ERROR%c", term);
        return -1;
    } else {
        if (listen(sockfd, 1) == -1) {
            logg("!ScanStream: listen() error on socket. Error returned is %s.\n", strerror(errno));
            closesocket(sockfd);
            return -1;
        }
        if (mdprintf(odesc, "PORT %u%c", port, term) <= 0) {
            logg("!ScanStream: error transmitting port.\n");
            closesocket(sockfd);
            return -1;
        }
    }

    retval = poll_fd(sockfd, firsttimeout, 0);
    if (!retval || retval == -1) {
        const char *reason = !retval ? "timeout" : "poll";
        mdprintf(odesc, "Accept %s. ERROR%c", reason, term);
        logg("!ScanStream %u: accept %s.\n", port, reason);
        closesocket(sockfd);
        return -1;
    }

    addrlen = sizeof(peer);
    if ((acceptd = accept(sockfd, (struct sockaddr *)&peer, (socklen_t *)&addrlen)) == -1) {
        closesocket(sockfd);
        mdprintf(odesc, "accept() ERROR%c", term);
        logg("!ScanStream %u: accept() failed.\n", port);
        return -1;
    }

    *peer_addr = '\0';
    inet_ntop(peer.sin_family, &peer.sin_addr, peer_addr, sizeof(peer_addr));
    logg("*Accepted connection from %s on port %u, fd %d\n", peer_addr, port, acceptd);

    if (cli_gentempfd(optget(opts, "TemporaryDirectory")->strarg, &tmpname, &tmpd)) {
        shutdown(sockfd, 2);
        closesocket(sockfd);
        closesocket(acceptd);
        mdprintf(odesc, "cli_gentempfd() failed. ERROR%c", term);
        logg("!ScanStream(%s@%u): Can't create temporary file.\n", peer_addr, port);
        return -1;
    }

    quota = maxsize = optget(opts, "StreamMaxLength")->numarg;

    while ((retval = poll_fd(acceptd, timeout, 0)) == 1) {
        /* only read up to max */
        btread = (maxsize && (quota < sizeof(buff))) ? quota : sizeof(buff);
        if (!btread) {
            logg("^ScanStream(%s@%u): Size limit reached (max: %lu)\n", peer_addr, port, maxsize);
            break; /* Scan what we have */
        }
        bread = recv(acceptd, buff, btread, 0);
        if (bread <= 0)
            break;

        quota -= bread;

        if (writen(tmpd, buff, bread) != bread) {
            shutdown(sockfd, 2);
            closesocket(sockfd);
            closesocket(acceptd);
            mdprintf(odesc, "Temporary file -> write ERROR%c", term);
            logg("!ScanStream(%s@%u): Can't write to temporary file.\n", peer_addr, port);
            close(tmpd);
            if (!optget(opts, "LeaveTemporaryFiles")->enabled)
                unlink(tmpname);
            free(tmpname);
            return -1;
        }
    }

    switch (retval) {
        case 0: /* timeout */
            mdprintf(odesc, "read timeout ERROR%c", term);
            logg("!ScanStream(%s@%u): read timeout.\n", peer_addr, port);
            break;
        case -1:
            mdprintf(odesc, "read poll ERROR%c", term);
            logg("!ScanStream(%s@%u): read poll failed.\n", peer_addr, port);
            break;
    }

    if (retval == 1) {
        lseek(tmpd, 0, SEEK_SET);
        thrmgr_setactivetask(peer_addr, NULL);
        context.filename = peer_addr;
        context.virsize  = 0;
        context.scandata = NULL;
        ret              = cl_scandesc_callback(tmpd, tmpname, &virname, scanned, engine, options, &context);
        thrmgr_setactivetask(NULL, NULL);
    } else {
        ret = -1;
    }
    close(tmpd);
    if (!optget(opts, "LeaveTemporaryFiles")->enabled)
        unlink(tmpname);
    free(tmpname);

    closesocket(acceptd);
    closesocket(sockfd);

    if (ret == CL_VIRUS) {
        if (context.virsize && optget(opts, "ExtendedDetectionInfo")->enabled) {
            mdprintf(odesc, "stream: %s(%s:%llu) FOUND%c", virname, context.virhash, context.virsize, term);
            logg("stream(%s@%u): %s(%s:%llu) FOUND\n", peer_addr, port, virname, context.virhash, context.virsize);
        } else {
            mdprintf(odesc, "stream: %s FOUND%c", virname, term);
            logg("stream(%s@%u): %s FOUND\n", peer_addr, port, virname);
        }
        virusaction("stream", virname, opts);
    } else if (ret != CL_CLEAN) {
        if (retval == 1) {
            mdprintf(odesc, "stream: %s ERROR%c", cl_strerror(ret), term);
            logg("stream(%s@%u): %s ERROR\n", peer_addr, port, cl_strerror(ret));
        }
    } else {
        mdprintf(odesc, "stream: OK%c", term);
        if (logok)
            logg("stream(%s@%u): OK\n", peer_addr, port);
    }

    return ret;
}