unixd.c

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                              const char * const *env,
                              apr_procattr_t *attr, ap_unix_identity_t *ugid,
                              apr_pool_t *p)
{
    int i = 0;
    const char **newargs;
    char *newprogname;
    char *execuser, *execgroup;
    const char *argv0;

    if (!unixd_config.suexec_enabled) {
        return apr_proc_create(newproc, progname, args, env, attr, p);
    }

    argv0 = ap_strrchr_c(progname, '/');
    /* Allow suexec's "/" check to succeed */
    if (argv0 != NULL) {
        argv0++;
    }
    else {
        argv0 = progname;
    }


    if (ugid->userdir) {
        execuser = apr_psprintf(p, "~%ld", (long) ugid->uid);
    }
    else {
        execuser = apr_psprintf(p, "%ld", (long) ugid->uid);
    }
    execgroup = apr_psprintf(p, "%ld", (long) ugid->gid);

    if (!execuser || !execgroup) {
        return APR_ENOMEM;
    }

    i = 0;
    if (args) {
        while (args[i]) {
            i++;
	    }
    }
    /* allocate space for 4 new args, the input args, and a null terminator */
    newargs = apr_palloc(p, sizeof(char *) * (i + 4));
    newprogname = SUEXEC_BIN;
    newargs[0] = SUEXEC_BIN;
    newargs[1] = execuser;
    newargs[2] = execgroup;
    newargs[3] = apr_pstrdup(p, argv0);

    /*
    ** using a shell to execute suexec makes no sense thus
    ** we force everything to be APR_PROGRAM, and never
    ** APR_SHELLCMD
    */
    if(apr_procattr_cmdtype_set(attr, APR_PROGRAM) != APR_SUCCESS) {
        return APR_EGENERAL;
    }

    i = 1;
    do {
        newargs[i + 3] = args[i];
    } while (args[i++]);

    return apr_proc_create(newproc, newprogname, newargs, env, attr, p);
}

AP_DECLARE(apr_status_t) ap_os_create_privileged_process(
    const request_rec *r,
    apr_proc_t *newproc, const char *progname,
    const char * const *args,
    const char * const *env,
    apr_procattr_t *attr, apr_pool_t *p)
{
    ap_unix_identity_t *ugid = ap_run_get_suexec_identity(r);

    if (ugid == NULL) {
        return apr_proc_create(newproc, progname, args, env, attr, p);
    }

    return ap_unix_create_privileged_process(newproc, progname, args, env,
                                              attr, ugid, p);
}

/* XXX move to APR and externalize (but implement differently :) ) */
static apr_lockmech_e proc_mutex_mech(apr_proc_mutex_t *pmutex)
{
    const char *mechname = apr_proc_mutex_name(pmutex);

    if (!strcmp(mechname, "sysvsem")) {
        return APR_LOCK_SYSVSEM;
    }
    else if (!strcmp(mechname, "flock")) {
        return APR_LOCK_FLOCK;
    }
    return APR_LOCK_DEFAULT;
}

AP_DECLARE(apr_status_t) unixd_set_proc_mutex_perms(apr_proc_mutex_t *pmutex)
{
    if (!geteuid()) {
        apr_lockmech_e mech = proc_mutex_mech(pmutex);

        switch(mech) {
#if APR_HAS_SYSVSEM_SERIALIZE
        case APR_LOCK_SYSVSEM:
        {
            apr_os_proc_mutex_t ospmutex;
#if !APR_HAVE_UNION_SEMUN
            union semun {
                long val;
                struct semid_ds *buf;
                unsigned short *array;
            };
#endif
            union semun ick;
            struct semid_ds buf;
        
            apr_os_proc_mutex_get(&ospmutex, pmutex);
            buf.sem_perm.uid = unixd_config.user_id;
            buf.sem_perm.gid = unixd_config.group_id;
            buf.sem_perm.mode = 0600;
            ick.buf = &buf;
            if (semctl(ospmutex.crossproc, 0, IPC_SET, ick) < 0) {
                return errno;
            }
        }
        break;
#endif
#if APR_HAS_FLOCK_SERIALIZE
        case APR_LOCK_FLOCK:
        {
            const char *lockfile = apr_proc_mutex_lockfile(pmutex);

            if (lockfile) {
                if (chown(lockfile, unixd_config.user_id,
                          -1 /* no gid change */) < 0) {
                    return errno;
                }
            }
        }
        break;
#endif
        default:
            /* do nothing */
            break;
        }
    }
    return APR_SUCCESS;
}

AP_DECLARE(apr_status_t) unixd_set_global_mutex_perms(apr_global_mutex_t *gmutex)
{
#if !APR_PROC_MUTEX_IS_GLOBAL
    apr_os_global_mutex_t osgmutex;
    apr_os_global_mutex_get(&osgmutex, gmutex);
    return unixd_set_proc_mutex_perms(osgmutex.proc_mutex);
#else  /* APR_PROC_MUTEX_IS_GLOBAL */
    /* In this case, apr_proc_mutex_t and apr_global_mutex_t are the same. */
    return unixd_set_proc_mutex_perms(gmutex);
#endif /* APR_PROC_MUTEX_IS_GLOBAL */
}

AP_DECLARE(apr_status_t) unixd_accept(void **accepted, ap_listen_rec *lr,
                                        apr_pool_t *ptrans)
{
    apr_socket_t *csd;
    apr_status_t status;

    *accepted = NULL;
    status = apr_accept(&csd, lr->sd, ptrans);
    if (status == APR_SUCCESS) { 
        *accepted = csd;
        return APR_SUCCESS;
    }

    if (APR_STATUS_IS_EINTR(status)) {
        return status;
    }
    /* Our old behaviour here was to continue after accept()
     * errors.  But this leads us into lots of troubles
     * because most of the errors are quite fatal.  For
     * example, EMFILE can be caused by slow descriptor
     * leaks (say in a 3rd party module, or libc).  It's
     * foolish for us to continue after an EMFILE.  We also
     * seem to tickle kernel bugs on some platforms which
     * lead to never-ending loops here.  So it seems best
     * to just exit in most cases.
     */
    switch (status) {
#if defined(HPUX11) && defined(ENOBUFS)
        /* On HPUX 11.x, the 'ENOBUFS, No buffer space available'
         * error occurs because the accept() cannot complete.
         * You will not see ENOBUFS with 10.20 because the kernel
         * hides any occurrence from being returned to user space.
         * ENOBUFS with 11.x's TCP/IP stack is possible, and could
         * occur intermittently. As a work-around, we are going to
         * ignore ENOBUFS.
         */
        case ENOBUFS:
#endif

#ifdef EPROTO
        /* EPROTO on certain older kernels really means
         * ECONNABORTED, so we need to ignore it for them.
         * See discussion in new-httpd archives nh.9701
         * search for EPROTO.
         *
         * Also see nh.9603, search for EPROTO:
         * There is potentially a bug in Solaris 2.x x<6,
         * and other boxes that implement tcp sockets in
         * userland (i.e. on top of STREAMS).  On these
         * systems, EPROTO can actually result in a fatal
         * loop.  See PR#981 for example.  It's hard to
         * handle both uses of EPROTO.
         */
        case EPROTO:
#endif
#ifdef ECONNABORTED
        case ECONNABORTED:
#endif
        /* Linux generates the rest of these, other tcp
         * stacks (i.e. bsd) tend to hide them behind
         * getsockopt() interfaces.  They occur when
         * the net goes sour or the client disconnects
         * after the three-way handshake has been done
         * in the kernel but before userland has picked
         * up the socket.
         */
#ifdef ECONNRESET
        case ECONNRESET:
#endif
#ifdef ETIMEDOUT
        case ETIMEDOUT:
#endif
#ifdef EHOSTUNREACH
        case EHOSTUNREACH:
#endif
#ifdef ENETUNREACH
        case ENETUNREACH:
#endif
        /* EAGAIN/EWOULDBLOCK can be returned on BSD-derived
         * TCP stacks when the connection is aborted before
         * we call connect, but only because our listener
         * sockets are non-blocking (AP_NONBLOCK_WHEN_MULTI_LISTEN)
         */
#ifdef EAGAIN
        case EAGAIN:
#endif
#ifdef EWOULDBLOCK
#if !defined(EAGAIN) || EAGAIN != EWOULDBLOCK
        case EWOULDBLOCK:
#endif
#endif
            break;
#ifdef ENETDOWN
        case ENETDOWN:
            /*
             * When the network layer has been shut down, there
             * is not much use in simply exiting: the parent
             * would simply re-create us (and we'd fail again).
             * Use the CHILDFATAL code to tear the server down.
             * @@@ Martin's idea for possible improvement:
             * A different approach would be to define
             * a new APEXIT_NETDOWN exit code, the reception
             * of which would make the parent shutdown all
             * children, then idle-loop until it detected that
             * the network is up again, and restart the children.
             * Ben Hyde noted that temporary ENETDOWN situations
             * occur in mobile IP.
             */
            ap_log_error(APLOG_MARK, APLOG_EMERG, status, ap_server_conf,
                         "apr_accept: giving up.");
            return APR_EGENERAL;
#endif /*ENETDOWN*/

#ifdef TPF
        case EINACT:
            ap_log_error(APLOG_MARK, APLOG_EMERG, status, ap_server_conf,
                         "offload device inactive");
            return APR_EGENERAL;
            break;
        default:
            ap_log_error(APLOG_MARK, APLOG_ERR, 0, ap_server_conf,
                         "select/accept error (%d)", status);
            return APR_EGENERAL;
#else
        default:
            ap_log_error(APLOG_MARK, APLOG_ERR, status, ap_server_conf,
                         "apr_accept: (client socket)");
            return APR_EGENERAL;
#endif
    }
    return status;
}