freebsd-dev/sys/netinet/ip_ftp_pxy.c
1999-11-23 21:44:59 +00:00

461 lines
9.6 KiB
C

/*
* Simple FTP transparent proxy for in-kernel use. For use with the NAT
* code.
*
* $Id$
* $FreeBSD$
*/
#if SOLARIS && defined(_KERNEL)
extern kmutex_t ipf_rw;
#endif
#define isdigit(x) ((x) >= '0' && (x) <= '9')
#define IPF_FTP_PROXY
#define IPF_MINPORTLEN 18
#define IPF_MAXPORTLEN 30
#define IPF_MIN227LEN 39
#define IPF_MAX227LEN 51
int ippr_ftp_init __P((void));
int ippr_ftp_out __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *));
int ippr_ftp_in __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *));
int ippr_ftp_portmsg __P((fr_info_t *, ip_t *, nat_t *));
int ippr_ftp_pasvmsg __P((fr_info_t *, ip_t *, nat_t *));
u_short ipf_ftp_atoi __P((char **));
static frentry_t natfr;
/*
* 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;
}
/*
* ipf_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 ipf_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;
}
int ippr_ftp_portmsg(fin, ip, nat)
fr_info_t *fin;
ip_t *ip;
nat_t *nat;
{
char portbuf[IPF_MAXPORTLEN + 1], newbuf[IPF_MAXPORTLEN + 1], *s;
tcphdr_t *tcp, tcph, *tcp2 = &tcph;
size_t nlen = 0, dlen, olen;
u_short a5, a6, sp, dp;
u_int a1, a2, a3, a4;
struct in_addr swip;
int off, inc = 0;
fr_info_t fi;
nat_t *ipn;
mb_t *m;
#if SOLARIS
mb_t *m1;
#endif
tcp = (tcphdr_t *)fin->fin_dp;
bzero(portbuf, sizeof(portbuf));
off = (ip->ip_hl << 2) + (tcp->th_off << 2);
#if SOLARIS
m = fin->fin_qfm;
dlen = msgdsize(m) - off;
if (dlen > 0)
copyout_mblk(m, off, MIN(sizeof(portbuf), dlen), portbuf);
#else
m = *(mb_t **)fin->fin_mp;
dlen = mbufchainlen(m) - off;
if (dlen > 0)
m_copydata(m, off, MIN(sizeof(portbuf), dlen), portbuf);
#endif
if (dlen == 0)
return 0;
portbuf[sizeof(portbuf) - 1] = '\0';
*newbuf = '\0';
if (!strncmp(portbuf, "PORT ", 5)) {
if (dlen < IPF_MINPORTLEN)
return 0;
} else
return 0;
/*
* Skip the PORT command + space
*/
s = portbuf + 5;
/*
* Pick out the address components, two at a time.
*/
a1 = ipf_ftp_atoi(&s);
if (!s)
return 0;
a2 = ipf_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 = ipf_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 - portbuf;
(void) snprintf(newbuf, sizeof(newbuf), "%s %u,%u,%u,%u,%u,%u\r\n",
"PORT", a1, a2, a3, a4, a5, a6);
nlen = strlen(newbuf);
inc = nlen - olen;
#if SOLARIS
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
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)
register 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);
#endif
ip->ip_len += inc;
}
/*
* Add skeleton NAT entry for connection which will come back the
* other way.
*/
sp = htons(a5 << 8 | a6);
/*
* 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) {
bcopy((char *)fin, (char *)&fi, sizeof(fi));
bzero((char *)tcp2, sizeof(*tcp2));
tcp2->th_win = htons(8192);
tcp2->th_sport = sp;
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_src = swip;
}
return inc;
}
int ippr_ftp_out(fin, ip, aps, nat)
fr_info_t *fin;
ip_t *ip;
ap_session_t *aps;
nat_t *nat;
{
return ippr_ftp_portmsg(fin, ip, nat);
}
int ippr_ftp_pasvmsg(fin, ip, nat)
fr_info_t *fin;
ip_t *ip;
nat_t *nat;
{
char portbuf[IPF_MAX227LEN + 1], newbuf[IPF_MAX227LEN + 1], *s;
int off, olen, dlen, nlen = 0, inc = 0;
tcphdr_t tcph, *tcp2 = &tcph;
struct in_addr swip, swip2;
u_short a5, a6, dp, sp;
u_int a1, a2, a3, a4;
tcphdr_t *tcp;
fr_info_t fi;
nat_t *ipn;
mb_t *m;
#if SOLARIS
mb_t *m1;
#endif
tcp = (tcphdr_t *)fin->fin_dp;
off = (ip->ip_hl << 2) + (tcp->th_off << 2);
m = *(mb_t **)fin->fin_mp;
bzero(portbuf, sizeof(portbuf));
#if SOLARIS
m = fin->fin_qfm;
dlen = msgdsize(m) - off;
if (dlen > 0)
copyout_mblk(m, off, MIN(sizeof(portbuf), dlen), portbuf);
#else
dlen = mbufchainlen(m) - off;
if (dlen > 0)
m_copydata(m, off, MIN(sizeof(portbuf), dlen), portbuf);
#endif
if (dlen == 0)
return 0;
portbuf[sizeof(portbuf) - 1] = '\0';
*newbuf = '\0';
if (!strncmp(portbuf, "227 ", 4)) {
if (dlen < IPF_MIN227LEN)
return 0;
else if (strncmp(portbuf, "227 Entering Passive Mode", 25))
return 0;
} else
return 0;
/*
* Skip the PORT command + space
*/
s = portbuf + 25;
while (*s && !isdigit(*s))
s++;
/*
* Pick out the address components, two at a time.
*/
a1 = ipf_ftp_atoi(&s);
if (!s)
return 0;
a2 = ipf_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 = ipf_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;
olen = s - portbuf;
(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 SOLARIS
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
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)
register 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);
#endif
ip->ip_len += inc;
}
/*
* 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) {
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 */
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_src = swip;
ip->ip_dst = swip2;
}
return inc;
}
int ippr_ftp_in(fin, ip, aps, nat)
fr_info_t *fin;
ip_t *ip;
ap_session_t *aps;
nat_t *nat;
{
return ippr_ftp_pasvmsg(fin, ip, nat);
}