URL
https://opencores.org/ocsvn/or1k/or1k/trunk
Subversion Repositories or1k
[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [net/] [ipv4/] [ip_masq_ftp.c] - Rev 1629
Go to most recent revision | Compare with Previous | Blame | View Log
/* * IP_MASQ_FTP ftp masquerading module * * * Version: @(#)ip_masq_ftp.c 0.01 02/05/96 * * Author: Wouter Gadeyne * * * Fixes: * Wouter Gadeyne : Fixed masquerading support of ftp PORT commands * Juan Jose Ciarlante : Code moved and adapted from ip_fw.c * Keith Owens : Add keep alive for ftp control channel * Nigel Metheringham : Added multiple port support * * * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Multiple Port Support * The helper can be made to handle up to MAX_MASQ_APP_PORTS (normally 12) * with the port numbers being defined at module load time. The module * uses the symbol "ports" to define a list of monitored ports, which can * be specified on the insmod command line as * ports=x1,x2,x3... * where x[n] are integer port numbers. This option can be put into * /etc/conf.modules (or /etc/modules.conf depending on your config) * where modload will pick it up should you use modload to load your * modules. * */ #include <linux/module.h> #include <asm/system.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/skbuff.h> #include <linux/in.h> #include <linux/ip.h> #include <net/protocol.h> #include <net/tcp.h> #include <net/ip_masq.h> #ifndef DEBUG_CONFIG_IP_MASQ_FTP #define DEBUG_CONFIG_IP_MASQ_FTP 0 #endif #ifdef MODULE #define STATIC #else #define STATIC static #endif /* * List of ports (up to MAX_MASQ_APP_PORTS) to be handled by helper * First port is set to the default port. */ STATIC int ports[MAX_MASQ_APP_PORTS] = {21}; /* I rely on the trailing items being set to zero */ struct ip_masq_app *masq_incarnations[MAX_MASQ_APP_PORTS]; static int masq_ftp_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms) { MOD_INC_USE_COUNT; return 0; } static int masq_ftp_done_1 (struct ip_masq_app *mapp, struct ip_masq *ms) { MOD_DEC_USE_COUNT; return 0; } int masq_ftp_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, struct device *dev) { struct sk_buff *skb; struct iphdr *iph; struct tcphdr *th; char *p, *data, *data_limit; unsigned char p1,p2,p3,p4,p5,p6; __u32 from; __u16 port; struct ip_masq *n_ms; char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */ unsigned buf_len; int diff; skb = *skb_p; iph = skb->h.iph; th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); data = (char *)&th[1]; data_limit = skb->h.raw + skb->len - 18; if (skb->len >= 6 && (memcmp(data, "PASV\r\n", 6) == 0 || memcmp(data, "pasv\r\n", 6) == 0)) ms->flags |= IP_MASQ_F_FTP_PASV; while (data < data_limit) { if (memcmp(data,"PORT ",5) && memcmp(data,"port ",5)) { data ++; continue; } p = data+5; p1 = simple_strtoul(data+5,&data,10); if (*data!=',') continue; p2 = simple_strtoul(data+1,&data,10); if (*data!=',') continue; p3 = simple_strtoul(data+1,&data,10); if (*data!=',') continue; p4 = simple_strtoul(data+1,&data,10); if (*data!=',') continue; p5 = simple_strtoul(data+1,&data,10); if (*data!=',') continue; p6 = simple_strtoul(data+1,&data,10); if (*data!='\r' && *data!='\n') continue; from = (p1<<24) | (p2<<16) | (p3<<8) | p4; port = (p5<<8) | p6; #if DEBUG_CONFIG_IP_MASQ_FTP printk("PORT %X:%X detected\n",from,port); #endif /* * Now update or create an masquerade entry for it */ #if DEBUG_CONFIG_IP_MASQ_FTP printk("protocol %d %lX:%X %X:%X\n", iph->protocol, htonl(from), htons(port), iph->daddr, 0); #endif n_ms = ip_masq_out_get_2(iph->protocol, htonl(from), htons(port), iph->daddr, 0); if (n_ms) { /* existing masquerade, clear timer */ ip_masq_set_expire(n_ms,0); } else { n_ms = ip_masq_new(dev, IPPROTO_TCP, htonl(from), htons(port), iph->daddr, 0, IP_MASQ_F_NO_DPORT); if (n_ms==NULL) return 0; n_ms->control = ms; /* keepalive from data to the control channel */ ms->flags |= IP_MASQ_F_CONTROL; /* this is a control channel */ } /* * keep for a bit longer than tcp_fin, caller may not reissue * PORT before tcp_fin_timeout. */ ip_masq_set_expire(n_ms, ip_masq_expire->tcp_fin_timeout*3); /* * Replace the old PORT with the new one */ from = ntohl(n_ms->maddr); port = ntohs(n_ms->mport); sprintf(buf,"%d,%d,%d,%d,%d,%d", from>>24&255,from>>16&255,from>>8&255,from&255, port>>8&255,port&255); buf_len = strlen(buf); #if DEBUG_CONFIG_IP_MASQ_FTP printk("new PORT %X:%X\n",from,port); #endif /* * Calculate required delta-offset to keep TCP happy */ diff = buf_len - (data-p); /* * No shift. */ if (diff==0) { /* * simple case, just replace the old PORT cmd */ memcpy(p,buf,buf_len); return 0; } *skb_p = ip_masq_skb_replace(skb, GFP_ATOMIC, p, data-p, buf, buf_len); return diff; } return 0; } /* * Look at incoming ftp packets to catch the response to a PASV command. When * we see one we build a masquerading entry for the client address, client port * 0 (unknown at the moment), the server address and the server port. Mark the * current masquerade entry as a control channel and point the new entry at the * control entry. All this work just for ftp keepalive across masquerading. * * The incoming packet should be something like * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)". * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number. * ncftp 2.3.0 cheats by skipping the leading number then going 22 bytes into * the data so we do the same. If it's good enough for ncftp then it's good * enough for me. * * In this case, the client is the source machine being masqueraded, the server * is the destination for ftp requests. It all depends on your point of view ... */ int masq_ftp_in (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, struct device *dev) { struct sk_buff *skb; struct iphdr *iph; struct tcphdr *th; char *data, *data_limit; unsigned char p1,p2,p3,p4,p5,p6; __u32 to; __u16 port; struct ip_masq *n_ms; if (! ms->flags & IP_MASQ_F_FTP_PASV) return 0; /* quick exit if no outstanding PASV */ skb = *skb_p; iph = skb->h.iph; th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); data = (char *)&th[1]; data_limit = skb->h.raw + skb->len; while (data < data_limit && *data != ' ') ++data; while (data < data_limit && *data == ' ') ++data; data += 22; if (data >= data_limit || *data != '(') return 0; p1 = simple_strtoul(data+1, &data, 10); if (data >= data_limit || *data != ',') return 0; p2 = simple_strtoul(data+1, &data, 10); if (data >= data_limit || *data != ',') return 0; p3 = simple_strtoul(data+1, &data, 10); if (data >= data_limit || *data != ',') return 0; p4 = simple_strtoul(data+1, &data, 10); if (data >= data_limit || *data != ',') return 0; p5 = simple_strtoul(data+1, &data, 10); if (data >= data_limit || *data != ',') return 0; p6 = simple_strtoul(data+1, &data, 10); if (data >= data_limit || *data != ')') return 0; to = (p1<<24) | (p2<<16) | (p3<<8) | p4; port = (p5<<8) | p6; /* * Now update or create an masquerade entry for it */ #if DEBUG_CONFIG_IP_MASQ_FTP printk("PASV response %lX:%X %X:%X detected\n", ntohl(ms->saddr), 0, to, port); #endif n_ms = ip_masq_out_get_2(iph->protocol, ms->saddr, 0, htonl(to), htons(port)); if (n_ms) { /* existing masquerade, clear timer */ ip_masq_set_expire(n_ms,0); } else { n_ms = ip_masq_new(dev, IPPROTO_TCP, ms->saddr, 0, htonl(to), htons(port), IP_MASQ_F_NO_SPORT); if (n_ms==NULL) return 0; n_ms->control = ms; /* keepalive from data to the control channel */ ms->flags |= IP_MASQ_F_CONTROL; /* this is a control channel */ } /* * keep for a bit longer than tcp_fin, client may not issue open * to server port before tcp_fin_timeout. */ ip_masq_set_expire(n_ms, ip_masq_expire->tcp_fin_timeout*3); ms->flags &= ~IP_MASQ_F_FTP_PASV; return 0; /* no diff required for incoming packets, thank goodness */ } struct ip_masq_app ip_masq_ftp = { NULL, /* next */ "ftp", /* name */ 0, /* type */ 0, /* n_attach */ masq_ftp_init_1, /* ip_masq_init_1 */ masq_ftp_done_1, /* ip_masq_done_1 */ masq_ftp_out, /* pkt_out */ masq_ftp_in, /* pkt_in */ }; /* * ip_masq_ftp initialization */ int ip_masq_ftp_init(void) { int i, j; for (i=0; (i<MAX_MASQ_APP_PORTS); i++) { if (ports[i]) { if ((masq_incarnations[i] = kmalloc(sizeof(struct ip_masq_app), GFP_KERNEL)) == NULL) return -ENOMEM; memcpy(masq_incarnations[i], &ip_masq_ftp, sizeof(struct ip_masq_app)); if ((j = register_ip_masq_app(masq_incarnations[i], IPPROTO_TCP, ports[i]))) { return j; } #if DEBUG_CONFIG_IP_MASQ_FTP printk("Ftp: loaded support on port[%d] = %d\n", i, ports[i]); #endif } else { /* To be safe, force the incarnation table entry to NULL */ masq_incarnations[i] = NULL; } } return 0; } /* * ip_masq_ftp fin. */ int ip_masq_ftp_done(void) { int i, j, k; k=0; for (i=0; (i<MAX_MASQ_APP_PORTS); i++) { if (masq_incarnations[i]) { if ((j = unregister_ip_masq_app(masq_incarnations[i]))) { k = j; } else { kfree(masq_incarnations[i]); masq_incarnations[i] = NULL; #if DEBUG_CONFIG_IP_MASQ_FTP printk("Ftp: unloaded support on port[%d] = %d\n", i, ports[i]); #endif } } } return k; } #ifdef MODULE int init_module(void) { if (ip_masq_ftp_init() != 0) return -EIO; register_symtab(0); return 0; } void cleanup_module(void) { if (ip_masq_ftp_done() != 0) printk("ip_masq_ftp: can't remove module"); } #endif /* MODULE */
Go to most recent revision | Compare with Previous | Blame | View Log