diff options
Diffstat (limited to 'net/ipv4/ip_masq_ftp.c')
-rw-r--r-- | net/ipv4/ip_masq_ftp.c | 244 |
1 files changed, 207 insertions, 37 deletions
diff --git a/net/ipv4/ip_masq_ftp.c b/net/ipv4/ip_masq_ftp.c index 4cb88d925..5313f4429 100644 --- a/net/ipv4/ip_masq_ftp.c +++ b/net/ipv4/ip_masq_ftp.c @@ -2,14 +2,20 @@ * IP_MASQ_FTP ftp masquerading module * * - * Version: @(#)ip_masq_ftp.c 0.01 02/05/96 + * Version: @(#)ip_masq_ftp.c 0.04 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 + * Juan Jose Ciarlante : Use control_add() for ftp control chan + * Juan Jose Ciarlante : Litl bits for 2.1 + * Juan Jose Ciarlante : use ip_masq_listen() + * Juan Jose Ciarlante : use private app_data for own flag(s) * * * @@ -17,7 +23,18 @@ * 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/config.h> @@ -31,9 +48,28 @@ #include <linux/init.h> #include <net/protocol.h> #include <net/tcp.h> + +/* #define IP_MASQ_NDEBUG */ #include <net/ip_masq.h> -#define DEBUG_CONFIG_IP_MASQ_FTP 0 + +/* + * 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]; + +/* + * Debug level + */ +static int debug=0; + +MODULE_PARM(ports, "1-" __MODULE_STRING(MAX_MASQ_APP_PORTS) "i"); +MODULE_PARM(debug, "i"); + +/* Dummy variable */ +static int masq_ftp_pasv; static int masq_ftp_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms) @@ -70,6 +106,8 @@ masq_ftp_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb 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->app_data = &masq_ftp_pasv; while (data < data_limit) { @@ -100,39 +138,30 @@ masq_ftp_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb 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 + + IP_MASQ_DEBUG(1-debug, "PORT %X:%X detected\n",from,port); + /* * 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, + IP_MASQ_DEBUG(1-debug, "protocol %d %lX:%X %X:%X\n", iph->protocol, htonl(from), htons(port), iph->daddr, 0); + + n_ms = ip_masq_out_get(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(maddr, IPPROTO_TCP, + if (!n_ms) { + n_ms = ip_masq_new(IPPROTO_TCP, + maddr, 0, htonl(from), htons(port), iph->daddr, 0, IP_MASQ_F_NO_DPORT); if (n_ms==NULL) return 0; + ip_masq_control_add(n_ms, ms); } - /* - * 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 */ @@ -142,30 +171,34 @@ masq_ftp_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb 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 + + IP_MASQ_DEBUG(1-debug, "new PORT %X:%X\n",from,port); /* * Calculate required delta-offset to keep TCP happy */ - + diff = buf_len - (data-p); - + /* * No shift. */ - - if (diff==0) - { + + if (diff==0) { /* * simple case, just replace the old PORT cmd */ memcpy(p,buf,buf_len); - return 0; - } + } else { + + *skb_p = ip_masq_skb_replace(skb, GFP_ATOMIC, p, data-p, buf, buf_len); + } + /* + * Move tunnel to listen state + */ + ip_masq_listen(n_ms); + ip_masq_put(n_ms); - *skb_p = ip_masq_skb_replace(skb, GFP_ATOMIC, p, data-p, buf, buf_len); return diff; } @@ -173,6 +206,108 @@ masq_ftp_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb } +/* + * 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, __u32 maddr) +{ + 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->app_data != &masq_ftp_pasv) + return 0; /* quick exit if no outstanding PASV */ + + skb = *skb_p; + iph = skb->nh.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 + */ + IP_MASQ_DEBUG(1-debug, "PASV response %lX:%X %X:%X detected\n", ntohl(ms->saddr), 0, to, port); + + n_ms = ip_masq_out_get(iph->protocol, + ms->saddr, 0, + htonl(to), htons(port)); + if (!n_ms) { + n_ms = ip_masq_new(IPPROTO_TCP, + maddr, 0, + ms->saddr, 0, + htonl(to), htons(port), + IP_MASQ_F_NO_SPORT); + + if (n_ms==NULL) + return 0; + ip_masq_control_add(n_ms, ms); + } + +#if 0 /* v0.12 state processing */ + + /* + * keep for a bit longer than tcp_fin, client may not issue open + * to server port before tcp_fin_timeout. + */ + n_ms->timeout = ip_masq_expire->tcp_fin_timeout*3; +#endif + ms->app_data = NULL; + ip_masq_put(n_ms); + + return 0; /* no diff required for incoming packets, thank goodness */ +} + struct ip_masq_app ip_masq_ftp = { NULL, /* next */ "ftp", /* name */ @@ -181,7 +316,7 @@ struct ip_masq_app ip_masq_ftp = { masq_ftp_init_1, /* ip_masq_init_1 */ masq_ftp_done_1, /* ip_masq_done_1 */ masq_ftp_out, /* pkt_out */ - NULL /* pkt_in */ + masq_ftp_in, /* pkt_in */ }; /* @@ -190,7 +325,27 @@ struct ip_masq_app ip_masq_ftp = { __initfunc(int ip_masq_ftp_init(void)) { - return register_ip_masq_app(&ip_masq_ftp, IPPROTO_TCP, 21); + 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; + } + IP_MASQ_DEBUG(1-debug, "Ftp: loaded support on port[%d] = %d\n", + i, ports[i]); + } else { + /* To be safe, force the incarnation table entry to NULL */ + masq_incarnations[i] = NULL; + } + } + return 0; } /* @@ -199,7 +354,22 @@ __initfunc(int ip_masq_ftp_init(void)) int ip_masq_ftp_done(void) { - return unregister_ip_masq_app(&ip_masq_ftp); + 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; + IP_MASQ_DEBUG(1-debug, "Ftp: unloaded support on port[%d] = %d\n", + i, ports[i]); + } + } + } + return k; } #ifdef MODULE |