459 lines
9.6 KiB
C
459 lines
9.6 KiB
C
/*
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* Simple FTP transparent proxy for in-kernel use. For use with the NAT
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* code.
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* $FreeBSD$
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*/
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#if SOLARIS && defined(_KERNEL)
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extern kmutex_t ipf_rw;
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#endif
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#define isdigit(x) ((x) >= '0' && (x) <= '9')
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#define IPF_FTP_PROXY
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#define IPF_MINPORTLEN 18
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#define IPF_MAXPORTLEN 30
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#define IPF_MIN227LEN 39
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#define IPF_MAX227LEN 51
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int ippr_ftp_init __P((void));
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int ippr_ftp_out __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *));
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int ippr_ftp_in __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *));
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int ippr_ftp_portmsg __P((fr_info_t *, ip_t *, nat_t *));
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int ippr_ftp_pasvmsg __P((fr_info_t *, ip_t *, nat_t *));
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u_short ipf_ftp_atoi __P((char **));
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static frentry_t natfr;
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/*
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* Initialize local structures.
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*/
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int ippr_ftp_init()
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{
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bzero((char *)&natfr, sizeof(natfr));
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natfr.fr_ref = 1;
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natfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
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return 0;
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}
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/*
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* ipf_ftp_atoi - implement a version of atoi which processes numbers in
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* pairs separated by commas (which are expected to be in the range 0 - 255),
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* returning a 16 bit number combining either side of the , as the MSB and
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* LSB.
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*/
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u_short ipf_ftp_atoi(ptr)
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char **ptr;
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{
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register char *s = *ptr, c;
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register u_char i = 0, j = 0;
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while ((c = *s++) && isdigit(c)) {
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i *= 10;
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i += c - '0';
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}
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if (c != ',') {
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*ptr = NULL;
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return 0;
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}
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while ((c = *s++) && isdigit(c)) {
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j *= 10;
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j += c - '0';
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}
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*ptr = s;
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return (i << 8) | j;
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}
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int ippr_ftp_portmsg(fin, ip, nat)
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fr_info_t *fin;
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ip_t *ip;
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nat_t *nat;
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{
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char portbuf[IPF_MAXPORTLEN + 1], newbuf[IPF_MAXPORTLEN + 1], *s;
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tcphdr_t *tcp, tcph, *tcp2 = &tcph;
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size_t nlen = 0, dlen, olen;
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u_short a5, a6, sp, dp;
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u_int a1, a2, a3, a4;
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struct in_addr swip;
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int off, inc = 0;
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fr_info_t fi;
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nat_t *ipn;
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mb_t *m;
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#if SOLARIS
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mb_t *m1;
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#endif
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tcp = (tcphdr_t *)fin->fin_dp;
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bzero(portbuf, sizeof(portbuf));
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off = (ip->ip_hl << 2) + (tcp->th_off << 2);
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#if SOLARIS
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m = fin->fin_qfm;
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dlen = msgdsize(m) - off;
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if (dlen > 0)
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copyout_mblk(m, off, MIN(sizeof(portbuf), dlen), portbuf);
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#else
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m = *(mb_t **)fin->fin_mp;
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dlen = mbufchainlen(m) - off;
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if (dlen > 0)
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m_copydata(m, off, MIN(sizeof(portbuf), dlen), portbuf);
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#endif
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if (dlen == 0)
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return 0;
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portbuf[sizeof(portbuf) - 1] = '\0';
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*newbuf = '\0';
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if (!strncmp(portbuf, "PORT ", 5)) {
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if (dlen < IPF_MINPORTLEN)
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return 0;
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} else
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return 0;
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/*
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* Skip the PORT command + space
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*/
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s = portbuf + 5;
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/*
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* Pick out the address components, two at a time.
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*/
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a1 = ipf_ftp_atoi(&s);
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if (!s)
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return 0;
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a2 = ipf_ftp_atoi(&s);
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if (!s)
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return 0;
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/*
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* check that IP address in the PORT/PASV reply is the same as the
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* sender of the command - prevents using PORT for port scanning.
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*/
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a1 <<= 16;
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a1 |= a2;
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if (a1 != ntohl(nat->nat_inip.s_addr))
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return 0;
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a5 = ipf_ftp_atoi(&s);
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if (!s)
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return 0;
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if (*s == ')')
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s++;
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/*
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* check for CR-LF at the end.
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*/
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if (*s == '\n')
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s--;
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if ((*s == '\r') && (*(s + 1) == '\n')) {
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s += 2;
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a6 = a5 & 0xff;
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} else
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return 0;
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a5 >>= 8;
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/*
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* Calculate new address parts for PORT command
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*/
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a1 = ntohl(ip->ip_src.s_addr);
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a2 = (a1 >> 16) & 0xff;
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a3 = (a1 >> 8) & 0xff;
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a4 = a1 & 0xff;
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a1 >>= 24;
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olen = s - portbuf;
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(void) sprintf(newbuf, "%s %u,%u,%u,%u,%u,%u\r\n",
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"PORT", a1, a2, a3, a4, a5, a6);
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nlen = strlen(newbuf);
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inc = nlen - olen;
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#if SOLARIS
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for (m1 = m; m1->b_cont; m1 = m1->b_cont)
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;
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if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) {
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mblk_t *nm;
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/* alloc enough to keep same trailer space for lower driver */
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nm = allocb(nlen, BPRI_MED);
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PANIC((!nm),("ippr_ftp_out: allocb failed"));
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nm->b_band = m1->b_band;
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nm->b_wptr += nlen;
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m1->b_wptr -= olen;
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PANIC((m1->b_wptr < m1->b_rptr),
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("ippr_ftp_out: cannot handle fragmented data block"));
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linkb(m1, nm);
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} else {
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if (m1->b_datap->db_struiolim == m1->b_wptr)
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m1->b_datap->db_struiolim += inc;
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m1->b_datap->db_struioflag &= ~STRUIO_IP;
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m1->b_wptr += inc;
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}
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copyin_mblk(m, off, nlen, newbuf);
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#else
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if (inc < 0)
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m_adj(m, inc);
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/* the mbuf chain will be extended if necessary by m_copyback() */
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m_copyback(m, off, nlen, newbuf);
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#endif
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if (inc != 0) {
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#if SOLARIS || defined(__sgi)
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register u_32_t sum1, sum2;
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sum1 = ip->ip_len;
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sum2 = ip->ip_len + inc;
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/* Because ~1 == -2, We really need ~1 == -1 */
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if (sum1 > sum2)
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sum2--;
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sum2 -= sum1;
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sum2 = (sum2 & 0xffff) + (sum2 >> 16);
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fix_outcksum(&ip->ip_sum, sum2, 0);
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#endif
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ip->ip_len += inc;
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}
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/*
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* Add skeleton NAT entry for connection which will come back the
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* other way.
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*/
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sp = htons(a5 << 8 | a6);
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/*
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* The server may not make the connection back from port 20, but
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* it is the most likely so use it here to check for a conflicting
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* mapping.
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*/
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dp = htons(fin->fin_data[1] - 1);
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ipn = nat_outlookup(fin->fin_ifp, IPN_TCP, nat->nat_p, nat->nat_inip,
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ip->ip_dst, (dp << 16) | sp);
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if (ipn == NULL) {
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bcopy((char *)fin, (char *)&fi, sizeof(fi));
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bzero((char *)tcp2, sizeof(*tcp2));
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tcp2->th_win = htons(8192);
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tcp2->th_sport = sp;
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tcp2->th_dport = 0; /* XXX - don't specify remote port */
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fi.fin_data[0] = ntohs(sp);
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fi.fin_data[1] = 0;
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fi.fin_dp = (char *)tcp2;
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swip = ip->ip_src;
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ip->ip_src = nat->nat_inip;
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ipn = nat_new(nat->nat_ptr, ip, &fi, IPN_TCP|FI_W_DPORT,
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NAT_OUTBOUND);
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if (ipn != NULL) {
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ipn->nat_age = fr_defnatage;
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(void) fr_addstate(ip, &fi, FI_W_DPORT);
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}
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ip->ip_src = swip;
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}
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return inc;
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}
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int ippr_ftp_out(fin, ip, aps, nat)
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fr_info_t *fin;
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ip_t *ip;
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ap_session_t *aps;
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nat_t *nat;
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{
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return ippr_ftp_portmsg(fin, ip, nat);
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}
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int ippr_ftp_pasvmsg(fin, ip, nat)
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fr_info_t *fin;
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ip_t *ip;
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nat_t *nat;
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{
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char portbuf[IPF_MAX227LEN + 1], newbuf[IPF_MAX227LEN + 1], *s;
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int off, olen, dlen, nlen = 0, inc = 0;
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tcphdr_t tcph, *tcp2 = &tcph;
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struct in_addr swip, swip2;
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u_short a5, a6, dp, sp;
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u_int a1, a2, a3, a4;
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tcphdr_t *tcp;
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fr_info_t fi;
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nat_t *ipn;
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mb_t *m;
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#if SOLARIS
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mb_t *m1;
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#endif
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tcp = (tcphdr_t *)fin->fin_dp;
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off = (ip->ip_hl << 2) + (tcp->th_off << 2);
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m = *(mb_t **)fin->fin_mp;
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bzero(portbuf, sizeof(portbuf));
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#if SOLARIS
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m = fin->fin_qfm;
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dlen = msgdsize(m) - off;
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if (dlen > 0)
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copyout_mblk(m, off, MIN(sizeof(portbuf), dlen), portbuf);
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#else
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dlen = mbufchainlen(m) - off;
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if (dlen > 0)
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m_copydata(m, off, MIN(sizeof(portbuf), dlen), portbuf);
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#endif
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if (dlen == 0)
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return 0;
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portbuf[sizeof(portbuf) - 1] = '\0';
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*newbuf = '\0';
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if (!strncmp(portbuf, "227 ", 4)) {
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if (dlen < IPF_MIN227LEN)
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return 0;
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else if (strncmp(portbuf, "227 Entering Passive Mode", 25))
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return 0;
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} else
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return 0;
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/*
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* Skip the PORT command + space
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*/
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s = portbuf + 25;
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while (*s && !isdigit(*s))
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s++;
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/*
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* Pick out the address components, two at a time.
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*/
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a1 = ipf_ftp_atoi(&s);
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if (!s)
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return 0;
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a2 = ipf_ftp_atoi(&s);
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if (!s)
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return 0;
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/*
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* check that IP address in the PORT/PASV reply is the same as the
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* sender of the command - prevents using PORT for port scanning.
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*/
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a1 <<= 16;
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a1 |= a2;
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if (a1 != ntohl(nat->nat_oip.s_addr))
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return 0;
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a5 = ipf_ftp_atoi(&s);
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if (!s)
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return 0;
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if (*s == ')')
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s++;
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if (*s == '\n')
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s--;
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/*
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* check for CR-LF at the end.
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*/
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if ((*s == '\r') && (*(s + 1) == '\n')) {
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s += 2;
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a6 = a5 & 0xff;
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} else
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return 0;
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a5 >>= 8;
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/*
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* Calculate new address parts for 227 reply
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*/
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a1 = ntohl(ip->ip_src.s_addr);
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a2 = (a1 >> 16) & 0xff;
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a3 = (a1 >> 8) & 0xff;
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a4 = a1 & 0xff;
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a1 >>= 24;
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olen = s - portbuf;
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(void) sprintf(newbuf, "%s %u,%u,%u,%u,%u,%u\r\n",
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"227 Entering Passive Mode", a1, a2, a3, a4, a5, a6);
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nlen = strlen(newbuf);
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inc = nlen - olen;
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#if SOLARIS
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for (m1 = m; m1->b_cont; m1 = m1->b_cont)
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;
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if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) {
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mblk_t *nm;
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/* alloc enough to keep same trailer space for lower driver */
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nm = allocb(nlen, BPRI_MED);
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PANIC((!nm),("ippr_ftp_out: allocb failed"));
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nm->b_band = m1->b_band;
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nm->b_wptr += nlen;
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m1->b_wptr -= olen;
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PANIC((m1->b_wptr < m1->b_rptr),
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("ippr_ftp_out: cannot handle fragmented data block"));
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linkb(m1, nm);
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} else {
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m1->b_wptr += inc;
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}
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copyin_mblk(m, off, nlen, newbuf);
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#else
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if (inc < 0)
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m_adj(m, inc);
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/* the mbuf chain will be extended if necessary by m_copyback() */
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m_copyback(m, off, nlen, newbuf);
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#endif
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if (inc != 0) {
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#if SOLARIS || defined(__sgi)
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register u_32_t sum1, sum2;
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sum1 = ip->ip_len;
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sum2 = ip->ip_len + inc;
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/* Because ~1 == -2, We really need ~1 == -1 */
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if (sum1 > sum2)
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sum2--;
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sum2 -= sum1;
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sum2 = (sum2 & 0xffff) + (sum2 >> 16);
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fix_outcksum(&ip->ip_sum, sum2, 0);
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#endif
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ip->ip_len += inc;
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}
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/*
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* Add skeleton NAT entry for connection which will come back the
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* other way.
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*/
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sp = 0;
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dp = htons(fin->fin_data[1] - 1);
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ipn = nat_outlookup(fin->fin_ifp, IPN_TCP, nat->nat_p, nat->nat_inip,
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ip->ip_dst, (dp << 16) | sp);
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if (ipn == NULL) {
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bcopy((char *)fin, (char *)&fi, sizeof(fi));
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bzero((char *)tcp2, sizeof(*tcp2));
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tcp2->th_win = htons(8192);
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tcp2->th_sport = 0; /* XXX - fake it for nat_new */
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fi.fin_data[0] = a5 << 8 | a6;
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tcp2->th_dport = htons(fi.fin_data[0]);
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fi.fin_data[1] = 0;
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fi.fin_dp = (char *)tcp2;
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swip = ip->ip_src;
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swip2 = ip->ip_dst;
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ip->ip_dst = ip->ip_src;
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ip->ip_src = nat->nat_inip;
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ipn = nat_new(nat->nat_ptr, ip, &fi, IPN_TCP|FI_W_SPORT,
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NAT_OUTBOUND);
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if (ipn != NULL) {
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ipn->nat_age = fr_defnatage;
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(void) fr_addstate(ip, &fi, FI_W_SPORT);
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}
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ip->ip_src = swip;
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ip->ip_dst = swip2;
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}
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return inc;
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}
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int ippr_ftp_in(fin, ip, aps, nat)
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fr_info_t *fin;
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ip_t *ip;
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ap_session_t *aps;
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nat_t *nat;
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{
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return ippr_ftp_pasvmsg(fin, ip, nat);
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}
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