clamav/clamd/clamd_others.c

/*
 *  Copyright (C) 2013-2024 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 *  Copyright (C) 2007-2013 Sourcefire, Inc.
 *
 *  Authors: Tomasz Kojm, Trog, 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

/* must be first because it may define _XOPEN_SOURCE */
#include "fdpassing.h"
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>
#include <time.h>
#include <sys/stat.h>
#include <errno.h>
#ifndef _WIN32
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#endif

#if HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_FILIO_H
#include <sys/filio.h>
#endif

#include <pthread.h>

#if HAVE_POLL
#if HAVE_POLL_H
#include <poll.h>
#else /* HAVE_POLL_H */
#if HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif /* HAVE_SYS_SELECT_H */
#endif /* HAVE_POLL_H */
#endif /* HAVE_POLL */

#include <limits.h>

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

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

#include "clamd_others.h"

static pthread_mutex_t virusaction_lock = PTHREAD_MUTEX_INITIALIZER;

static void xfree(void *p)
{
    if (p)
        free(p);
}

#ifdef _WIN32
void virusaction(const char *filename, const char *virname,
                 const struct optstruct *opts)
{
    if (optget(opts, "VirusEvent")->enabled)
        logg(LOGG_WARNING, "VirusEvent is not supported on this platform"); /* Yet */
}

#else

#define VE_FILENAME "CLAM_VIRUSEVENT_FILENAME"
#define VE_VIRUSNAME "CLAM_VIRUSEVENT_VIRUSNAME"

#define FILENAME_DISABLED_MESSAGE "The filename format character has been disabled due to security concerns, use the 'CLAM_VIRUSEVENT_FILENAME' environment variable instead."

void virusaction(const char *filename, const char *virname,
                 const struct optstruct *opts)
{
    pid_t pid;
    const struct optstruct *opt;
    char *buffer_file, *buffer_vir, *buffer_cmd, *path;
    const char *pt;
    size_t i, j, v = 0, f = 0, len;
    char *env[4];

    if (!(opt = optget(opts, "VirusEvent"))->enabled)
        return;

    path   = getenv("PATH");
    env[0] = path ? strdup(path) : NULL;
    j      = env[0] ? 1 : 0;
    /* Allocate env vars.. to be portable env vars should not be freed */
    buffer_file =
        (char *)malloc(strlen(VE_FILENAME) + strlen(filename) + 2);
    if (buffer_file) {
        sprintf(buffer_file, "%s=%s", VE_FILENAME, filename);
        env[j++] = buffer_file;
    }

    buffer_vir =
        (char *)malloc(strlen(VE_VIRUSNAME) + strlen(virname) + 2);
    if (buffer_vir) {
        sprintf(buffer_vir, "%s=%s", VE_VIRUSNAME, virname);
        env[j++] = buffer_vir;
    }
    env[j++] = NULL;

    pt = opt->strarg;
    while ((pt = strstr(pt, "%v"))) {
        pt += 2;
        v++;
    }
    pt = opt->strarg;
    while ((pt = strstr(pt, "%f"))) {
        pt += 2;
        f++;
    }
    len = strlen(opt->strarg);
    buffer_cmd =
        (char *)calloc(len + v * strlen(virname) + f * strlen(FILENAME_DISABLED_MESSAGE) + 1, sizeof(char));
    if (!buffer_cmd) {
        if (path)
            xfree(env[0]);

        xfree(buffer_file);
        xfree(buffer_vir);
        return;
    }
    for (i = 0, j = 0; i < len; i++) {
        if (i + 1 < len && opt->strarg[i] == '%' && opt->strarg[i + 1] == 'v') {
            strcat(buffer_cmd, virname);
            j += strlen(virname);
            i++;
        } else if (i + 1 < len && opt->strarg[i] == '%' && opt->strarg[i + 1] == 'f') {
            strcat(buffer_cmd, FILENAME_DISABLED_MESSAGE);
            j += strlen(FILENAME_DISABLED_MESSAGE);
            i++;
        } else {
            buffer_cmd[j++] = opt->strarg[i];
        }
    }

    pthread_mutex_lock(&virusaction_lock);
    /* We can only call async-signal-safe functions after fork(). */
    pid = vfork();
    if (pid == 0) { /* child */
        _exit(execle("/bin/sh", "sh", "-c", buffer_cmd, NULL, env));
    } else if (pid > 0) { /* parent */
        pthread_mutex_unlock(&virusaction_lock);
        while (waitpid(pid, NULL, 0) == -1 && errno == EINTR) continue;
    } else {
        pthread_mutex_unlock(&virusaction_lock);
        logg(LOGG_ERROR, "VirusEvent: fork failed.\n");
    }
    if (path)
        xfree(env[0]);

    xfree(buffer_cmd);
    xfree(buffer_file);
    xfree(buffer_vir);
}
#endif /* _WIN32 */

/* Function: writen
        Try hard to write the specified number of bytes
*/
int writen(int fd, void *buff, unsigned int count)
{
    int retval;
    unsigned int todo;
    unsigned char *current;

    todo    = count;
    current = (unsigned char *)buff;

    do {
        retval = write(fd, current, todo);
        if (retval < 0) {
            if (errno == EINTR) {
                continue;
            }
            return -1;
        }
        todo -= retval;
        current += retval;
    } while (todo > 0);

    return count;
}

static int
realloc_polldata(struct fd_data *data)
{
#ifdef HAVE_POLL
    if (data->poll_data_nfds == data->nfds)
        return 0;
    if (data->poll_data)
        free(data->poll_data);
    data->poll_data = malloc(data->nfds * sizeof(*data->poll_data));
    if (!data->poll_data) {
        logg(LOGG_ERROR, "realloc_polldata: Memory allocation failed for poll_data\n");
        return -1;
    }
    data->poll_data_nfds = data->nfds;
#endif
    return 0;
}

int poll_fd(int fd, int timeout_sec, int check_signals)
{
    int ret;
    struct fd_data fds = FDS_INIT(NULL);

    if (fds_add(&fds, fd, 1, timeout_sec) == -1)
        return -1;
    do {
        ret = fds_poll_recv(&fds, timeout_sec, check_signals, NULL);
    } while (ret == -1 && errno == EINTR);
    fds_free(&fds);
    return ret;
}

void fds_cleanup(struct fd_data *data)
{
    struct fd_buf *newbuf;
    unsigned i, j;

    for (i = 0, j = 0; i < data->nfds; i++) {
        if (data->buf[i].fd < 0) {
            if (data->buf[i].buffer)
                free(data->buf[i].buffer);
            continue;
        }
        if (i != j)
            data->buf[j] = data->buf[i];
        j++;
    }
    if (j == data->nfds)
        return;
    for (i = j; i < data->nfds; i++)
        data->buf[i].fd = -1;
    data->nfds = j;
    logg(LOGG_DEBUG_NV, "Number of file descriptors polled: %u fds\n",
         (unsigned)data->nfds);
    /* Shrink buffer */
    newbuf = realloc(data->buf, j * sizeof(*newbuf));
    if (!j)
        data->buf = NULL;
    else if (newbuf)
        data->buf = newbuf; /* non-fatal if shrink fails */
}

static int
read_fd_data(struct fd_buf *buf)
{
    ssize_t n;

    buf->got_newdata = 1;
    if (!buf->buffer) /* listen-only socket */
        return 1;

    if (buf->off >= buf->bufsize)
        return -1;

        /* Read the pending packet, it may contain more than one command, but
         * that is to the cmdparser to handle.
         * It will handle 1st command, and then move leftover to beginning of buffer
         */
#ifdef HAVE_FD_PASSING
    {
        struct msghdr msg;
        struct cmsghdr *cmsg;
        union {
            unsigned char buff[CMSG_SPACE(sizeof(int))];
            struct cmsghdr hdr;
        } b;
        struct iovec iov[1];

        if (buf->recvfd != -1) {
            logg(LOGG_DEBUG_NV, "Closing unclaimed FD: %d\n", buf->recvfd);
            close(buf->recvfd);
            buf->recvfd = -1;
        }
        memset(&msg, 0, sizeof(msg));
        iov[0].iov_base    = buf->buffer + buf->off;
        iov[0].iov_len     = buf->bufsize - buf->off;
        msg.msg_iov        = iov;
        msg.msg_iovlen     = 1;
        msg.msg_control    = b.buff;
        msg.msg_controllen = sizeof(b.buff);

        n = recvmsg(buf->fd, &msg, 0);
        if (n < 0)
            return -1;
        if (msg.msg_flags & MSG_TRUNC) {
            logg(LOGG_WARNING, "Message truncated at %d bytes\n", (int)n);
            return -1;
        }
        if (msg.msg_flags & MSG_CTRUNC) {
            if (msg.msg_controllen > 0)
                logg(LOGG_WARNING, "Control message truncated at %d bytes, %d data read\n", (int)msg.msg_controllen, (int)n);
            else
                logg(LOGG_WARNING, "Control message truncated, no control data received, %d bytes read"
#ifdef C_LINUX
                                   "(Is SELinux/AppArmor enabled, and blocking file descriptor passing?)"
#endif
                                   "\n",
                     (int)n);
            return -1;
        }
        if (msg.msg_controllen) {
            for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
                 cmsg = CMSG_NXTHDR(&msg, cmsg)) {
                if (cmsg->cmsg_len == CMSG_LEN(sizeof(int)) &&
                    cmsg->cmsg_level == SOL_SOCKET &&
                    cmsg->cmsg_type == SCM_RIGHTS) {
                    if (buf->recvfd != -1) {
                        logg(LOGG_DEBUG_NV, "Unclaimed file descriptor received. closing: %d\n", buf->recvfd);
                        close(buf->recvfd);
                    }
                    buf->recvfd = *(int *)CMSG_DATA(cmsg);
                    logg(LOGG_DEBUG_NV, "Received a file descriptor: %d\n", buf->recvfd);
                }
            }
        }
    }
#else
    n = recv(buf->fd, buf->buffer + buf->off, buf->bufsize - buf->off, 0);
    if (n < 0)
        return -1;
#endif
    buf->off += n;
    return n;
}

static int
buf_init(struct fd_buf *buf, int listen_only, int timeout)
{
    buf->off         = 0;
    buf->got_newdata = 0;
    buf->recvfd      = -1;
    buf->mode        = MODE_COMMAND;
    buf->id          = 0;
    buf->dumpfd      = -1;
    buf->chunksize   = 0;
    buf->quota       = 0;
    buf->dumpname    = NULL;
    buf->group       = NULL;
    buf->term        = '\0';
    if (!listen_only) {
        if (!buf->buffer) {
            buf->bufsize = PATH_MAX + 8;
            /* plus extra space for a \0 so we can make sure every command is \0
             * terminated */
            if (!(buf->buffer = malloc(buf->bufsize + 1))) {
                logg(LOGG_ERROR, "add_fd: Memory allocation failed for command buffer\n");
                return -1;
            }
        }
    } else {
        if (buf->buffer)
            free(buf->buffer);
        buf->bufsize = 0;
        buf->buffer  = NULL;
    }
    if (timeout) {
        time(&buf->timeout_at);
        buf->timeout_at += timeout;
    } else {
        buf->timeout_at = 0;
    }
    return 0;
}

int fds_add(struct fd_data *data, int fd, int listen_only, int timeout)
{
    struct fd_buf *buf;
    unsigned n;
    if (fd < 0) {
        logg(LOGG_ERROR, "add_fd: invalid fd passed to add_fd\n");
        return -1;
    }
    /* we may already have this fd, if
     * the old FD got closed, and the kernel reused the FD */
    for (n = 0; n < data->nfds; n++)
        if (data->buf[n].fd == fd) {
            /* clear stale data in buffer */
            if (buf_init(&data->buf[n], listen_only, timeout) < 0)
                return -1;
            return 0;
        }

    n++;
    buf = realloc(data->buf, n * sizeof(*buf));
    if (!buf) {
        logg(LOGG_ERROR, "add_fd: Memory allocation failed for fd_buf\n");
        return -1;
    }
    data->buf               = buf;
    data->nfds              = n;
    data->buf[n - 1].buffer = NULL;
    if (buf_init(&data->buf[n - 1], listen_only, timeout) < 0)
        return -1;
    data->buf[n - 1].fd = fd;
    return 0;
}

static inline void
fds_lock(struct fd_data *data)
{
    if (data->buf_mutex)
        pthread_mutex_lock(data->buf_mutex);
}

static inline void
fds_unlock(struct fd_data *data)
{
    if (data->buf_mutex)
        pthread_mutex_unlock(data->buf_mutex);
}

void fds_remove(struct fd_data *data, int fd)
{
    size_t i;
    fds_lock(data);
    if (data->buf) {
        for (i = 0; i < data->nfds; i++) {
            if (data->buf[i].fd == fd) {
                data->buf[i].fd = -1;
                break;
            }
        }
    }
    fds_unlock(data);
}

#define BUFFSIZE 1024
/* Wait till data is available to be read on any of the fds,
 * read available data on all fds, and mark them as appropriate.
 * One of the fds should be a pipe, used by the accept thread to wake us.
 * timeout is specified in seconds, if check_signals is non-zero, then
 * poll_recv_fds() will return upon receipt of a signal, even if no data
 * is received on any of the sockets.
 * Must be called with buf_mutex lock held.
 */
/* TODO: handle ReadTimeout */
int fds_poll_recv(struct fd_data *data, int timeout, int check_signals,
                  void *event)
{
    unsigned fdsok = data->nfds;
    size_t i;
    int retval;
    time_t now, closest_timeout;

    UNUSEDPARAM(event);

    /* we must have at least one fd, the control fd! */
    fds_cleanup(data);
#ifndef _WIN32
    if (!data->nfds)
        return 0;
#endif
    for (i = 0; i < data->nfds; i++) {
        data->buf[i].got_newdata = 0;
    }

    time(&now);
    if (timeout > 0)
        closest_timeout = now + timeout;
    else
        closest_timeout = 0;
    for (i = 0; i < data->nfds; i++) {
        time_t timeout_at = data->buf[i].timeout_at;
        if (timeout_at && timeout_at < now) {
            /* timed out */
            data->buf[i].got_newdata = -2;
            /* we must return immediately from poll/select, we have a timeout! */
            closest_timeout = now;
        } else {
            if (!closest_timeout)
                closest_timeout = timeout_at;
            else if (timeout_at && timeout_at < closest_timeout)
                closest_timeout = timeout_at;
        }
    }
    if (closest_timeout)
        timeout = closest_timeout - now;
    else
        timeout = -1;
    if (timeout > 0)
        logg(LOGG_DEBUG_NV, "fds_poll_recv: timeout after %d seconds\n", timeout);
#ifdef HAVE_POLL
    /* Use poll() if available, preferred because:
     *  - can poll any number of FDs
     *  - can notify of both data available / socket disconnected events
     *  - when it says POLLIN it is guaranteed that a following recv() won't
     *  block (select may say that data is available to read, but a following
     *  recv() may still block according to the manpage
     */

    if (realloc_polldata(data) == -1)
        return -1;
    if (timeout > 0) {
        /* seconds to ms */
        timeout *= 1000;
    }
    for (i = 0; i < data->nfds; i++) {
        data->poll_data[i].fd      = data->buf[i].fd;
        data->poll_data[i].events  = POLLIN;
        data->poll_data[i].revents = 0;
    }
    do {
        int n = data->nfds;

        fds_unlock(data);
#ifdef _WIN32
        retval = poll_with_event(data->poll_data, n, timeout, event);
#else
        retval = poll(data->poll_data, n, timeout);
#endif
        fds_lock(data);

        if (retval > 0) {
            fdsok = 0;
            /* nfds may change during poll, but not
             * poll_data_nfds */
            for (i = 0; i < data->poll_data_nfds; i++) {
                short revents;
                if (data->buf[i].fd < 0)
                    continue;
                if (data->buf[i].fd != data->poll_data[i].fd) {
                    /* should never happen */
                    logg(LOGG_ERROR, "poll_recv_fds FD mismatch\n");
                    continue;
                }
                revents = data->poll_data[i].revents;
                if (revents & (POLLIN | POLLHUP)) {
                    logg(LOGG_DEBUG_NV, "Received POLLIN|POLLHUP on fd %d\n",
                         data->poll_data[i].fd);
                }
#ifndef _WIN32
                if (revents & POLLHUP) {
                    /* avoid SHUT_WR problem on Mac OS X */
                    int ret = send(data->poll_data[i].fd, &n, 0, 0);
                    if (!ret || (ret == -1 && errno == EINTR))
                        revents &= ~POLLHUP;
                }
#endif
                if (revents & POLLIN) {
                    int ret = read_fd_data(&data->buf[i]);
                    /* Data available to be read */
                    if (ret == -1)
                        revents |= POLLERR;
                    else if (!ret)
                        revents = POLLHUP;
                }

                if (revents & (POLLHUP | POLLERR | POLLNVAL)) {
                    if (revents & (POLLHUP | POLLNVAL)) {
                        /* remote disconnected */
                        logg(LOGG_DEBUG, "Client disconnected (FD %d)\n",
                             data->poll_data[i].fd);
                    } else {
                        /* error on file descriptor */
                        logg(LOGG_WARNING, "Error condition on fd %d\n",
                             data->poll_data[i].fd);
                    }
                    data->buf[i].got_newdata = -1;
                } else {
                    fdsok++;
                }
            }
        }
    } while (retval == -1 && !check_signals && errno == EINTR);
#else
    {
        fd_set rfds;
        struct timeval tv;
        int maxfd = -1;

        for (i = 0; i < data->nfds; i++) {
            int fd = data->buf[i].fd;
            if (fd >= FD_SETSIZE) {
                logg(LOGG_ERROR, "File descriptor is too high for FD_SET\n");
                return -1;
            }

            maxfd = MAX(maxfd, fd);
        }

        do {
            FD_ZERO(&rfds);
            for (i = 0; i < data->nfds; i++) {
                int fd = data->buf[i].fd;
                if (fd >= 0)
                    FD_SET(fd, &rfds);
            }
            tv.tv_sec  = timeout;
            tv.tv_usec = 0;

            fds_unlock(data);
            retval =
                select(maxfd + 1, &rfds, NULL, NULL,
                       timeout >= 0 ? &tv : NULL);
            fds_lock(data);
            if (retval > 0) {
                fdsok = data->nfds;
                for (i = 0; i < data->nfds; i++) {
                    if (data->buf[i].fd < 0) {
                        fdsok--;
                        continue;
                    }
                    if (FD_ISSET(data->buf[i].fd, &rfds)) {
                        int ret = read_fd_data(&data->buf[i]);
                        if (ret == -1 || !ret) {
                            if (ret == -1)
                                logg(LOGG_ERROR, "Error condition on fd %d\n",
                                     data->buf[i].fd);
                            else {
                                /* avoid SHUT_WR problem on Mac OS X */
                                int ret = send(data->buf[i].fd, &i, 0, 0);
                                if (!ret || (ret == -1 && errno == EINTR))
                                    continue;
                                logg(LOGG_DEBUG, "Client disconnected\n");
                            }
                            data->buf[i].got_newdata = -1;
                        }
                    }
                }
            }
            if (retval < 0 && errno == EBADF) {
                /* unlike poll(),  select() won't tell us which FD is bad, so
                 * we have to check them one by one. */
                tv.tv_sec  = 0;
                tv.tv_usec = 0;
                /* with tv == 0 it doesn't check for EBADF */
                FD_ZERO(&rfds);
                for (i = 0; i < data->nfds; i++) {
                    if (data->buf[i].fd == -1)
                        continue;
                    FD_SET(data->buf[i].fd, &rfds);
                    do {
                        retval =
                            select(data->buf[i].fd + 1, &rfds, NULL, NULL,
                                   &tv);
                    } while (retval == -1 && errno == EINTR);
                    if (retval == -1) {
                        data->buf[i].fd = -1;
                    } else {
                        FD_CLR(data->buf[i].fd, &rfds);
                    }
                }
                retval = -1;
                errno  = EINTR;
                continue;
            }
        } while (retval == -1 && !check_signals && errno == EINTR);
    }
#endif

    if (retval == -1 && errno != EINTR) {
        char err[128];
#ifdef HAVE_POLL
        logg(LOGG_ERROR, "poll_recv_fds: poll failed: %s\n",
             cli_strerror(errno, err, sizeof(err)));
#else
        logg(LOGG_ERROR, "poll_recv_fds: select failed: %s\n",
             cli_strerror(errno, err, sizeof(err)));
#endif
    }

    return retval;
}

void fds_free(struct fd_data *data)
{
    unsigned i;
    fds_lock(data);
    for (i = 0; i < data->nfds; i++) {
        if (data->buf[i].buffer) {
            free(data->buf[i].buffer);
        }
    }
    if (data->buf)
        free(data->buf);
#ifdef HAVE_POLL
    if (data->poll_data)
        free(data->poll_data);
#endif
    data->buf  = NULL;
    data->nfds = 0;
    fds_unlock(data);
}