/* $NetBSD: ip_ftp_pxy.c,v 1.16 2000/05/21 18:45:54 veego Exp $ */ /* * Simple FTP transparent proxy for in-kernel use. For use with the NAT * code. * * Id: ip_ftp_pxy.c,v 2.7.2.7 2000/05/13 14:28:14 darrenr Exp */ #if SOLARIS && defined(_KERNEL) extern kmutex_t ipf_rw; #endif #define isdigit(x) ((x) >= '0' && (x) <= '9') #define isupper(x) ((unsigned)((x) - 'A') <= 'Z' - 'A') #define IPF_FTP_PROXY #define IPF_MINPORTLEN 18 #define IPF_MAXPORTLEN 30 #define IPF_MIN227LEN 39 #define IPF_MAX227LEN 51 #define IPF_FTPBUFSZ 96 /* This *MUST* be >= 53! */ int ippr_ftp_client __P((fr_info_t *, ip_t *, nat_t *, ftpinfo_t *, int)); int ippr_ftp_complete __P((char *, size_t)); int ippr_ftp_in __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *)); int ippr_ftp_init __P((void)); int ippr_ftp_new __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *)); int ippr_ftp_out __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *)); int ippr_ftp_pasv __P((fr_info_t *, ip_t *, nat_t *, ftpside_t *, int)); int ippr_ftp_port __P((fr_info_t *, ip_t *, nat_t *, ftpside_t *, int)); int ippr_ftp_process __P((fr_info_t *, ip_t *, nat_t *, ftpinfo_t *, int)); int ippr_ftp_server __P((fr_info_t *, ip_t *, nat_t *, ftpinfo_t *, int)); int ippr_ftp_valid __P((char *, size_t)); u_short ippr_ftp_atoi __P((char **)); static frentry_t natfr; int ippr_ftp_pasvonly = 0; /* * Initialize local structures. */ int ippr_ftp_init() { bzero((char *)&natfr, sizeof(natfr)); natfr.fr_ref = 1; natfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE; return 0; } int ippr_ftp_new(fin, ip, aps, nat) fr_info_t *fin; ip_t *ip; ap_session_t *aps; nat_t *nat; { ftpinfo_t *ftp; ftpside_t *f; KMALLOC(ftp, ftpinfo_t *); if (ftp == NULL) return -1; aps->aps_data = ftp; aps->aps_psiz = sizeof(ftpinfo_t); bzero((char *)ftp, sizeof(*ftp)); f = &ftp->ftp_side[0]; f->ftps_rptr = f->ftps_buf; f->ftps_wptr = f->ftps_buf; f = &ftp->ftp_side[1]; f->ftps_rptr = f->ftps_buf; f->ftps_wptr = f->ftps_buf; return 0; } int ippr_ftp_port(fin, ip, nat, f, dlen) fr_info_t *fin; ip_t *ip; nat_t *nat; ftpside_t *f; int dlen; { tcphdr_t *tcp, tcph, *tcp2 = &tcph; char newbuf[IPF_FTPBUFSZ], *s; u_short a5, a6, sp, dp; u_int a1, a2, a3, a4; struct in_addr swip; size_t nlen, olen; fr_info_t fi; int inc, off; nat_t *ipn; mb_t *m; #if SOLARIS mb_t *m1; #endif tcp = (tcphdr_t *)fin->fin_dp; off = f->ftps_seq - ntohl(tcp->th_seq); if (off < 0) return 0; /* * Check for client sending out PORT message. */ if (dlen < IPF_MINPORTLEN) return 0; /* * Count the number of bytes in the PORT message is. */ if (off < 0) return 0; off += fin->fin_hlen + (tcp->th_off << 2); /* * Skip the PORT command + space */ s = f->ftps_rptr + 5; /* * Pick out the address components, two at a time. */ a1 = ippr_ftp_atoi(&s); if (!s) return 0; a2 = ippr_ftp_atoi(&s); if (!s) return 0; /* * check that IP address in the PORT/PASV reply is the same as the * sender of the command - prevents using PORT for port scanning. */ a1 <<= 16; a1 |= a2; if (a1 != ntohl(nat->nat_inip.s_addr)) return 0; a5 = ippr_ftp_atoi(&s); if (!s) return 0; if (*s == ')') s++; /* * check for CR-LF at the end. */ if (*s == '\n') s--; if ((*s == '\r') && (*(s + 1) == '\n')) { s += 2; a6 = a5 & 0xff; } else return 0; a5 >>= 8; /* * Calculate new address parts for PORT command */ a1 = ntohl(ip->ip_src.s_addr); a2 = (a1 >> 16) & 0xff; a3 = (a1 >> 8) & 0xff; a4 = a1 & 0xff; a1 >>= 24; olen = s - f->ftps_rptr; /* DO NOT change this to sprintf! */ (void) sprintf(newbuf, "%s %u,%u,%u,%u,%u,%u\r\n", "PORT", a1, a2, a3, a4, a5, a6); nlen = strlen(newbuf); inc = nlen - olen; if ((inc + ip->ip_len) > 65535) return 0; #if SOLARIS m = fin->fin_qfm; for (m1 = m; m1->b_cont; m1 = m1->b_cont) ; if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) { mblk_t *nm; /* alloc enough to keep same trailer space for lower driver */ nm = allocb(nlen, BPRI_MED); PANIC((!nm),("ippr_ftp_out: allocb failed")); nm->b_band = m1->b_band; nm->b_wptr += nlen; m1->b_wptr -= olen; PANIC((m1->b_wptr < m1->b_rptr), ("ippr_ftp_out: cannot handle fragmented data block")); linkb(m1, nm); } else { if (m1->b_datap->db_struiolim == m1->b_wptr) m1->b_datap->db_struiolim += inc; m1->b_datap->db_struioflag &= ~STRUIO_IP; m1->b_wptr += inc; } copyin_mblk(m, off, nlen, newbuf); #else m = *((mb_t **)fin->fin_mp); if (inc < 0) m_adj(m, inc); /* the mbuf chain will be extended if necessary by m_copyback() */ m_copyback(m, off, nlen, newbuf); #endif if (inc != 0) { #if SOLARIS || defined(__sgi) u_32_t sum1, sum2; sum1 = ip->ip_len; sum2 = ip->ip_len + inc; /* Because ~1 == -2, We really need ~1 == -1 */ if (sum1 > sum2) sum2--; sum2 -= sum1; sum2 = (sum2 & 0xffff) + (sum2 >> 16); fix_outcksum(&ip->ip_sum, sum2, 0); #endif ip->ip_len += inc; } /* * Add skeleton NAT entry for connection which will come back the * other way. */ sp = htons(a5 << 8 | a6); /* * Don't allow the PORT command to specify a port < 1024 due to * security crap. */ if (ntohs(sp) < 1024) return 0; /* * The server may not make the connection back from port 20, but * it is the most likely so use it here to check for a conflicting * mapping. */ dp = htons(fin->fin_data[1] - 1); ipn = nat_outlookup(fin->fin_ifp, IPN_TCP, nat->nat_p, nat->nat_inip, ip->ip_dst, (dp << 16) | sp); if (ipn == NULL) { int slen; slen = ip->ip_len; ip->ip_len = fin->fin_hlen + sizeof(*tcp2); bcopy((char *)fin, (char *)&fi, sizeof(fi)); bzero((char *)tcp2, sizeof(*tcp2)); tcp2->th_win = htons(8192); tcp2->th_sport = sp; tcp2->th_off = 5; tcp2->th_dport = 0; /* XXX - don't specify remote port */ fi.fin_data[0] = ntohs(sp); fi.fin_data[1] = 0; fi.fin_dp = (char *)tcp2; swip = ip->ip_src; ip->ip_src = nat->nat_inip; ipn = nat_new(nat->nat_ptr, ip, &fi, IPN_TCP|FI_W_DPORT, NAT_OUTBOUND); if (ipn != NULL) { ipn->nat_age = fr_defnatage; (void) fr_addstate(ip, &fi, FI_W_DPORT); } ip->ip_len = slen; ip->ip_src = swip; } return inc; } int ippr_ftp_client(fin, ip, nat, ftp, dlen) fr_info_t *fin; nat_t *nat; ftpinfo_t *ftp; ip_t *ip; int dlen; { char *rptr, *wptr; ftpside_t *f; int inc; inc = 0; f = &ftp->ftp_side[0]; rptr = f->ftps_rptr; wptr = f->ftps_wptr; if ((ftp->ftp_passok == 0) && !strncmp(rptr, "USER ", 5)) ftp->ftp_passok = 1; else if ((ftp->ftp_passok == 2) && !strncmp(rptr, "PASS ", 5)) ftp->ftp_passok = 3; else if ((ftp->ftp_passok == 4) && !ippr_ftp_pasvonly && !strncmp(rptr, "PORT ", 5)) { inc = ippr_ftp_port(fin, ip, nat, f, dlen); } while ((*rptr++ != '\n') && (rptr < wptr)) ; f->ftps_seq += rptr - f->ftps_rptr; f->ftps_rptr = rptr; return inc; } int ippr_ftp_pasv(fin, ip, nat, f, dlen) fr_info_t *fin; ip_t *ip; nat_t *nat; ftpside_t *f; int dlen; { tcphdr_t *tcp, tcph, *tcp2 = &tcph; struct in_addr swip, swip2; u_short a5, a6, sp, dp; u_int a1, a2, a3, a4; fr_info_t fi; int inc, off; nat_t *ipn; char *s; /* * Check for PASV reply message. */ if (dlen < IPF_MIN227LEN) return 0; else if (strncmp(f->ftps_rptr, "227 Entering Passive Mode", 25)) return 0; /* * Count the number of bytes in the 227 reply is. */ tcp = (tcphdr_t *)fin->fin_dp; off = f->ftps_seq - ntohl(tcp->th_seq); if (off < 0) return 0; off += fin->fin_hlen + (tcp->th_off << 2); /* * Skip the PORT command + space */ s = f->ftps_rptr + 25; while (*s && !isdigit(*s)) s++; /* * Pick out the address components, two at a time. */ a1 = ippr_ftp_atoi(&s); if (!s) return 0; a2 = ippr_ftp_atoi(&s); if (!s) return 0; /* * check that IP address in the PORT/PASV reply is the same as the * sender of the command - prevents using PORT for port scanning. */ a1 <<= 16; a1 |= a2; if (a1 != ntohl(nat->nat_oip.s_addr)) return 0; a5 = ippr_ftp_atoi(&s); if (!s) return 0; if (*s == ')') s++; if (*s == '\n') s--; /* * check for CR-LF at the end. */ if ((*s == '\r') && (*(s + 1) == '\n')) { s += 2; a6 = a5 & 0xff; } else return 0; a5 >>= 8; /* * Calculate new address parts for 227 reply */ a1 = ntohl(ip->ip_src.s_addr); a2 = (a1 >> 16) & 0xff; a3 = (a1 >> 8) & 0xff; a4 = a1 & 0xff; a1 >>= 24; inc = 0; #if 0 olen = s - f->ftps_rptr; (void) sprintf(newbuf, "%s %u,%u,%u,%u,%u,%u\r\n", "227 Entering Passive Mode", a1, a2, a3, a4, a5, a6); nlen = strlen(newbuf); inc = nlen - olen; if ((inc + ip->ip_len) > 65535) return 0; #if SOLARIS m = fin->fin_qfm; for (m1 = m; m1->b_cont; m1 = m1->b_cont) ; if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) { mblk_t *nm; /* alloc enough to keep same trailer space for lower driver */ nm = allocb(nlen, BPRI_MED); PANIC((!nm),("ippr_ftp_out: allocb failed")); nm->b_band = m1->b_band; nm->b_wptr += nlen; m1->b_wptr -= olen; PANIC((m1->b_wptr < m1->b_rptr), ("ippr_ftp_out: cannot handle fragmented data block")); linkb(m1, nm); } else { m1->b_wptr += inc; } /*copyin_mblk(m, off, nlen, newbuf);*/ #else m = *((mb_t **)fin->fin_mp); if (inc < 0) m_adj(m, inc); /* the mbuf chain will be extended if necessary by m_copyback() */ /*m_copyback(m, off, nlen, newbuf);*/ #endif if (inc != 0) { #if SOLARIS || defined(__sgi) u_32_t sum1, sum2; sum1 = ip->ip_len; sum2 = ip->ip_len + inc; /* Because ~1 == -2, We really need ~1 == -1 */ if (sum1 > sum2) sum2--; sum2 -= sum1; sum2 = (sum2 & 0xffff) + (sum2 >> 16); fix_outcksum(&ip->ip_sum, sum2, 0); #endif ip->ip_len += inc; } #endif /* * Add skeleton NAT entry for connection which will come back the * other way. */ sp = 0; dp = htons(fin->fin_data[1] - 1); ipn = nat_outlookup(fin->fin_ifp, IPN_TCP, nat->nat_p, nat->nat_inip, ip->ip_dst, (dp << 16) | sp); if (ipn == NULL) { int slen; slen = ip->ip_len; ip->ip_len = fin->fin_hlen + sizeof(*tcp2); bcopy((char *)fin, (char *)&fi, sizeof(fi)); bzero((char *)tcp2, sizeof(*tcp2)); tcp2->th_win = htons(8192); tcp2->th_sport = 0; /* XXX - fake it for nat_new */ tcp2->th_off = 5; fi.fin_data[0] = a5 << 8 | a6; tcp2->th_dport = htons(fi.fin_data[0]); fi.fin_data[1] = 0; fi.fin_dp = (char *)tcp2; swip = ip->ip_src; swip2 = ip->ip_dst; ip->ip_dst = ip->ip_src; ip->ip_src = nat->nat_inip; ipn = nat_new(nat->nat_ptr, ip, &fi, IPN_TCP|FI_W_SPORT, NAT_OUTBOUND); if (ipn != NULL) { ipn->nat_age = fr_defnatage; (void) fr_addstate(ip, &fi, FI_W_SPORT); } ip->ip_len = slen; ip->ip_src = swip; ip->ip_dst = swip2; } return inc; } int ippr_ftp_server(fin, ip, nat, ftp, dlen) fr_info_t *fin; ip_t *ip; nat_t *nat; ftpinfo_t *ftp; int dlen; { char *rptr, *wptr; ftpside_t *f; int inc; inc = 0; f = &ftp->ftp_side[1]; rptr = f->ftps_rptr; wptr = f->ftps_wptr; if ((ftp->ftp_passok == 1) && !strncmp(rptr, "331", 3)) ftp->ftp_passok = 2; else if ((ftp->ftp_passok == 3) && !strncmp(rptr, "230", 3)) ftp->ftp_passok = 4; else if ((ftp->ftp_passok == 3) && !strncmp(rptr, "530", 3)) ftp->ftp_passok = 0; else if ((ftp->ftp_passok == 4) && !strncmp(rptr, "227 ", 4)) { inc = ippr_ftp_pasv(fin, ip, nat, f, dlen); } while ((*rptr++ != '\n') && (rptr < wptr)) ; f->ftps_seq += rptr - f->ftps_rptr; f->ftps_rptr = rptr; return inc; } /* * Look to see if the buffer starts with something which we recognise as * being the correct syntax for the FTP protocol. */ int ippr_ftp_valid(buf, len) char *buf; size_t len; { register char *s, c; register size_t i = len; if (i < 5) return 2; s = buf; c = *s++; i--; if (isdigit(c)) { c = *s++; i--; if (isdigit(c)) { c = *s++; i--; if (isdigit(c)) { c = *s++; i--; if ((c != '-') && (c != ' ')) return 1; } else return 1; } else return 1; } else if (isupper(c)) { c = *s++; i--; if (isupper(c)) { c = *s++; i--; if (isupper(c)) { c = *s++; i--; if (isupper(c)) { c = *s++; i--; if ((c != ' ') && (c != '\r')) return 1; } else if ((c != ' ') && (c != '\r')) return 1; } else return 1; } else return 1; } else return 1; for (; i; i--) { c = *s++; if (c == '\n') return 0; } return 2; } int ippr_ftp_process(fin, ip, nat, ftp, rv) fr_info_t *fin; ip_t *ip; nat_t *nat; ftpinfo_t *ftp; int rv; { int mlen, len, off, inc, i; char *rptr, *wptr; tcphdr_t *tcp; ftpside_t *f; mb_t *m; tcp = (tcphdr_t *)fin->fin_dp; off = fin->fin_hlen + (tcp->th_off << 2); #if SOLARIS m = fin->fin_qfm; #else m = *((mb_t **)fin->fin_mp); #endif #if SOLARIS mlen = msgdsize(m) - off; #else mlen = mbufchainlen(m) - off; #endif if (!mlen) return 0; inc = 0; f = &ftp->ftp_side[rv]; rptr = f->ftps_rptr; wptr = f->ftps_wptr; if ((wptr == f->ftps_buf) && (f->ftps_seq <= ntohl(tcp->th_seq))) f->ftps_seq = ntohl(tcp->th_seq); /* * XXX - Ideally, this packet should get dropped because we now know * that it is out of order (and there is no real danger in doing so * apart from causing packets to go through here ordered). */ if (ntohl(tcp->th_seq) != f->ftps_seq + (wptr - rptr)) { return APR_ERR(0); } while (mlen > 0) { len = MIN(mlen, FTP_BUFSZ / 2); #if SOLARIS copyout_mblk(m, off, len, wptr); #else m_copydata(m, off, len, wptr); #endif mlen -= len; off += len; wptr += len; f->ftps_wptr = wptr; if (f->ftps_junk == 2) f->ftps_junk = ippr_ftp_valid(rptr, wptr - rptr); while ((f->ftps_junk == 0) && (wptr > rptr)) { f->ftps_junk = ippr_ftp_valid(rptr, wptr - rptr); if (f->ftps_junk == 0) { len = wptr - rptr; f->ftps_rptr = rptr; if (rv) inc += ippr_ftp_server(fin, ip, nat, ftp, len); else inc += ippr_ftp_client(fin, ip, nat, ftp, len); rptr = f->ftps_rptr; } } while ((f->ftps_junk == 1) && (rptr < wptr)) { while ((rptr < wptr) && (*rptr != '\r')) rptr++; if ((*rptr == '\r') && (rptr + 1 < wptr)) { if (*(rptr + 1) == '\n') { rptr += 2; f->ftps_junk = 0; } else rptr++; } f->ftps_seq += rptr - f->ftps_rptr; f->ftps_rptr = rptr; } if (rptr == wptr) { rptr = wptr = f->ftps_buf; } else { if ((wptr > f->ftps_buf + FTP_BUFSZ / 2)) { i = wptr - rptr; if ((rptr == f->ftps_buf) || (wptr - rptr > FTP_BUFSZ / 2)) { f->ftps_seq += i; f->ftps_junk = 1; rptr = wptr = f->ftps_buf; } else { bcopy(rptr, f->ftps_buf, i); wptr = f->ftps_buf + i; rptr = f->ftps_buf; } } f->ftps_rptr = rptr; f->ftps_wptr = wptr; } } f->ftps_rptr = rptr; f->ftps_wptr = wptr; return inc; } int ippr_ftp_out(fin, ip, aps, nat) fr_info_t *fin; ip_t *ip; ap_session_t *aps; nat_t *nat; { ftpinfo_t *ftp; ftp = aps->aps_data; if (ftp == NULL) return 0; return ippr_ftp_process(fin, ip, nat, ftp, 0); } int ippr_ftp_in(fin, ip, aps, nat) fr_info_t *fin; ip_t *ip; ap_session_t *aps; nat_t *nat; { ftpinfo_t *ftp; ftp = aps->aps_data; if (ftp == NULL) return 0; return ippr_ftp_process(fin, ip, nat, ftp, 1); } /* * ippr_ftp_atoi - implement a version of atoi which processes numbers in * pairs separated by commas (which are expected to be in the range 0 - 255), * returning a 16 bit number combining either side of the , as the MSB and * LSB. */ u_short ippr_ftp_atoi(ptr) char **ptr; { register char *s = *ptr, c; register u_char i = 0, j = 0; while ((c = *s++) && isdigit(c)) { i *= 10; i += c - '0'; } if (c != ',') { *ptr = NULL; return 0; } while ((c = *s++) && isdigit(c)) { j *= 10; j += c - '0'; } *ptr = s; return (i << 8) | j; }