Author: glebius Date: Sun Sep 9 09:46:48 2012 New Revision: 240271 URL: http://svn.freebsd.org/changeset/base/240271
Log: For UDP transport set IP_RECVDSTADDR sockopt on the socket, and provide IP_SENDSRCADDR control with datagram message we reply with. This makes bsnmpd reply from exactly same address that request was sent to, thus successfully bypassing stateful firewalls or other kinds of strict checking. PR: bin/171279 Modified: head/contrib/bsnmp/snmpd/main.c head/contrib/bsnmp/snmpd/trans_udp.c Modified: head/contrib/bsnmp/snmpd/main.c ============================================================================== --- head/contrib/bsnmp/snmpd/main.c Sun Sep 9 08:40:44 2012 (r240270) +++ head/contrib/bsnmp/snmpd/main.c Sun Sep 9 09:46:48 2012 (r240271) @@ -1106,10 +1106,11 @@ recv_stream(struct port_input *pi) * Each receive should return one datagram. */ static int -recv_dgram(struct port_input *pi) +recv_dgram(struct port_input *pi, struct in_addr *laddr) { u_char embuf[1000]; - char cbuf[CMSG_SPACE(SOCKCREDSIZE(CMGROUP_MAX))]; + char cbuf[CMSG_SPACE(SOCKCREDSIZE(CMGROUP_MAX)) + + CMSG_SPACE(sizeof(struct in_addr))]; struct msghdr msg; struct iovec iov[1]; ssize_t len; @@ -1159,6 +1160,9 @@ recv_dgram(struct port_input *pi) for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) { + if (cmsg->cmsg_level == IPPROTO_IP && + cmsg->cmsg_type == IP_RECVDSTADDR) + memcpy(laddr, CMSG_DATA(cmsg), sizeof(struct in_addr)); if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDS) cred = (struct sockcred *)CMSG_DATA(cmsg); @@ -1187,12 +1191,27 @@ snmpd_input(struct port_input *pi, struc #ifdef USE_TCPWRAPPERS char client[16]; #endif + struct msghdr msg; + struct iovec iov[1]; + char cbuf[CMSG_SPACE(sizeof(struct in_addr))]; + struct cmsghdr *cmsgp; /* get input depending on the transport */ if (pi->stream) { + msg.msg_control = NULL; + msg.msg_controllen = 0; + ret = recv_stream(pi); } else { - ret = recv_dgram(pi); + memset(cbuf, 0, CMSG_SPACE(sizeof(struct in_addr))); + msg.msg_control = cbuf; + msg.msg_controllen = CMSG_SPACE(sizeof(struct in_addr)); + cmsgp = CMSG_FIRSTHDR(&msg); + cmsgp->cmsg_len = CMSG_LEN(sizeof(struct in_addr)); + cmsgp->cmsg_level = IPPROTO_IP; + cmsgp->cmsg_type = IP_SENDSRCADDR; + + ret = recv_dgram(pi, (struct in_addr *)CMSG_DATA(cmsgp)); } if (ret == -1) @@ -1337,11 +1356,19 @@ snmpd_input(struct port_input *pi, struc sndbuf, &sndlen, "SNMP", ierr, vi, NULL); if (ferr == SNMPD_INPUT_OK) { - slen = sendto(pi->fd, sndbuf, sndlen, 0, pi->peer, pi->peerlen); + msg.msg_name = pi->peer; + msg.msg_namelen = pi->peerlen; + msg.msg_iov = iov; + msg.msg_iovlen = 1; + msg.msg_flags = 0; + iov[0].iov_base = sndbuf; + iov[0].iov_len = sndlen; + + slen = sendmsg(pi->fd, &msg, 0); if (slen == -1) - syslog(LOG_ERR, "sendto: %m"); + syslog(LOG_ERR, "sendmsg: %m"); else if ((size_t)slen != sndlen) - syslog(LOG_ERR, "sendto: short write %zu/%zu", + syslog(LOG_ERR, "sendmsg: short write %zu/%zu", sndlen, (size_t)slen); } snmp_pdu_free(&pdu); Modified: head/contrib/bsnmp/snmpd/trans_udp.c ============================================================================== --- head/contrib/bsnmp/snmpd/trans_udp.c Sun Sep 9 08:40:44 2012 (r240270) +++ head/contrib/bsnmp/snmpd/trans_udp.c Sun Sep 9 09:46:48 2012 (r240271) @@ -103,11 +103,19 @@ udp_init_port(struct tport *tp) struct udp_port *p = (struct udp_port *)tp; struct sockaddr_in addr; u_int32_t ip; + const int on = 1; if ((p->input.fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) { syslog(LOG_ERR, "creating UDP socket: %m"); return (SNMP_ERR_RES_UNAVAIL); } + if (setsockopt(p->input.fd, IPPROTO_IP, IP_RECVDSTADDR, &on, + sizeof(on)) == -1) { + syslog(LOG_ERR, "setsockopt(IP_RECVDSTADDR): %m"); + close(p->input.fd); + p->input.fd = -1; + return (SNMP_ERR_GENERR); + } ip = (p->addr[0] << 24) | (p->addr[1] << 16) | (p->addr[2] << 8) | p->addr[3]; memset(&addr, 0, sizeof(addr)); _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"