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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [net/] [ipv4/] [ip_masq_app.c] - Rev 1772
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/* * IP_MASQ_APP application masquerading module * * * Version: @(#)ip_masq_app.c 0.04 96/06/17 * * Author: Juan Jose Ciarlante, <jjciarla@raiz.uncu.edu.ar> * * * 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. * * Fixes: * JJC : Implemented also input pkt hook * Miquel van Smoorenburg : Copy more stuff when resizing skb * Harald Hoyer/James R. Leu: Additional ipautofw support * * * FIXME: * - ip_masq_skb_replace(): use same skb if space available. * */ #include <linux/config.h> #include <linux/module.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/skbuff.h> #include <linux/in.h> #include <linux/ip.h> #include <net/protocol.h> #include <net/tcp.h> #include <net/udp.h> #include <asm/system.h> #include <linux/stat.h> #include <linux/proc_fs.h> #include <net/ip_masq.h> static const char *strProt[] = {"UDP","TCP"}; static __inline__ const char * masq_proto_name(unsigned proto) { return strProt[proto==IPPROTO_TCP]; } #define IP_MASQ_APP_TAB_SIZE 16 /* must be power of 2 */ #define IP_MASQ_APP_HASH(proto, port) ((port^proto) & (IP_MASQ_APP_TAB_SIZE-1)) #define IP_MASQ_APP_TYPE(proto, port) ( proto<<16 | port ) #define IP_MASQ_APP_PORT(type) ( type & 0xffff ) #define IP_MASQ_APP_PROTO(type) ( (type>>16) & 0x00ff ) static struct symbol_table ip_masq_app_syms = { #include <linux/symtab_begin.h> X(register_ip_masq_app), X(unregister_ip_masq_app), X(ip_masq_skb_replace), #include <linux/symtab_end.h> }; /* * will hold masq app. hashed list heads */ struct ip_masq_app *ip_masq_app_base[IP_MASQ_APP_TAB_SIZE]; /* * ip_masq_app registration routine * port: host byte order. */ int register_ip_masq_app(struct ip_masq_app *mapp, unsigned short proto, __u16 port) { unsigned long flags; unsigned hash; if (!mapp) { printk("register_ip_masq_app(): NULL arg\n"); return -EINVAL; } mapp->type = IP_MASQ_APP_TYPE(proto, port); mapp->n_attach = 0; hash = IP_MASQ_APP_HASH(proto, port); save_flags(flags); cli(); mapp->next = ip_masq_app_base[hash]; ip_masq_app_base[hash] = mapp; restore_flags(flags); return 0; } /* * ip_masq_app unreg. routine. */ int unregister_ip_masq_app(struct ip_masq_app *mapp) { struct ip_masq_app **mapp_p; unsigned hash; unsigned long flags; if (!mapp) { printk("unregister_ip_masq_app(): NULL arg\n"); return -EINVAL; } /* * only allow unregistration if it has no attachments */ if (mapp->n_attach) { printk("unregister_ip_masq_app(): has %d attachments. failed\n", mapp->n_attach); return -EINVAL; } hash = IP_MASQ_APP_HASH(IP_MASQ_APP_PROTO(mapp->type), IP_MASQ_APP_PORT(mapp->type)); save_flags(flags); cli(); for (mapp_p = &ip_masq_app_base[hash]; *mapp_p ; mapp_p = &(*mapp_p)->next) if (mapp == (*mapp_p)) { *mapp_p = mapp->next; restore_flags(flags); return 0; } restore_flags(flags); printk("unregister_ip_masq_app(proto=%s,port=%u): not hashed!\n", masq_proto_name(IP_MASQ_APP_PROTO(mapp->type)), IP_MASQ_APP_PORT(mapp->type)); return -EINVAL; } /* * get ip_masq_app object by its proto and port (net byte order). */ struct ip_masq_app * ip_masq_app_get(unsigned short proto, __u16 port) { struct ip_masq_app *mapp; unsigned hash; unsigned type; port = ntohs(port); type = IP_MASQ_APP_TYPE(proto,port); hash = IP_MASQ_APP_HASH(proto,port); for(mapp = ip_masq_app_base[hash]; mapp ; mapp = mapp->next) { if (type == mapp->type) return mapp; } return NULL; } /* * ip_masq_app object binding related funcs. */ /* * change ip_masq_app object's number of bindings */ static __inline__ int ip_masq_app_bind_chg(struct ip_masq_app *mapp, int delta) { unsigned long flags; int n_at; if (!mapp) return -1; save_flags(flags); cli(); n_at = mapp->n_attach + delta; if (n_at < 0) { restore_flags(flags); printk("ip_masq_app: tried to set n_attach < 0 for (proto=%s,port==%d) ip_masq_app object.\n", masq_proto_name(IP_MASQ_APP_PROTO(mapp->type)), IP_MASQ_APP_PORT(mapp->type)); return -1; } mapp->n_attach = n_at; restore_flags(flags); return 0; } /* * Bind ip_masq to its ip_masq_app based on proto and dport ALREADY * set in ip_masq struct. Also calls constructor. */ struct ip_masq_app * ip_masq_bind_app(struct ip_masq *ms) { struct ip_masq_app * mapp; mapp = ip_masq_app_get(ms->protocol, ms->dport); #ifdef CONFIG_IP_MASQUERADE_IPAUTOFW if (mapp == NULL) mapp = ip_masq_app_get(ms->protocol, ms->sport); #endif if (mapp != NULL) { /* * don't allow binding if already bound */ if (ms->app != NULL) { printk("ip_masq_bind_app() called for already bound object.\n"); return ms->app; } ms->app = mapp; if (mapp->masq_init_1) mapp->masq_init_1(mapp, ms); ip_masq_app_bind_chg(mapp, +1); } return mapp; } /* * Unbind ms from type object and call ms destructor (does not kfree()). */ int ip_masq_unbind_app(struct ip_masq *ms) { struct ip_masq_app * mapp; mapp = ms->app; if (mapp != NULL) { if (mapp->masq_done_1) mapp->masq_done_1(mapp, ms); ms->app = NULL; ip_masq_app_bind_chg(mapp, -1); } return (mapp != NULL); } /* * Fixes th->seq based on ip_masq_seq info. */ static __inline__ void masq_fix_seq(const struct ip_masq_seq *ms_seq, struct tcphdr *th) { __u32 seq; seq = ntohl(th->seq); /* * Adjust seq with delta-offset for all packets after * the most recent resized pkt seq and with previous_delta offset * for all packets before most recent resized pkt seq. */ if (ms_seq->delta || ms_seq->previous_delta) { if(after(seq,ms_seq->init_seq) ) { th->seq = htonl(seq + ms_seq->delta); #if DEBUG_CONFIG_IP_MASQ_APP printk("masq_fix_seq() : added delta (%d) to seq\n",ms_seq->delta); #endif } else { th->seq = htonl(seq + ms_seq->previous_delta); #if DEBUG_CONFIG_IP_MASQ_APP printk("masq_fix_seq() : added previous_delta (%d) to seq\n",ms_seq->previous_delta); #endif } } } /* * Fixes th->ack_seq based on ip_masq_seq info. */ static __inline__ void masq_fix_ack_seq(const struct ip_masq_seq *ms_seq, struct tcphdr *th) { __u32 ack_seq; ack_seq=ntohl(th->ack_seq); /* * Adjust ack_seq with delta-offset for * the packets AFTER most recent resized pkt has caused a shift * for packets before most recent resized pkt, use previous_delta */ if (ms_seq->delta || ms_seq->previous_delta) { if(after(ack_seq,ms_seq->init_seq)) { th->ack_seq = htonl(ack_seq-ms_seq->delta); #if DEBUG_CONFIG_IP_MASQ_APP printk("masq_fix_ack_seq() : subtracted delta (%d) from ack_seq\n",ms_seq->delta); #endif } else { th->ack_seq = htonl(ack_seq-ms_seq->previous_delta); #if DEBUG_CONFIG_IP_MASQ_APP printk("masq_fix_ack_seq() : subtracted previous_delta (%d) from ack_seq\n",ms_seq->previous_delta); #endif } } } /* * Updates ip_masq_seq if pkt has been resized * Assumes already checked proto==IPPROTO_TCP and diff!=0. */ static __inline__ void masq_seq_update(struct ip_masq *ms, struct ip_masq_seq *ms_seq, unsigned mflag, __u32 seq, int diff) { /* if (diff == 0) return; */ if ( !(ms->flags & mflag) || after(seq, ms_seq->init_seq)) { ms_seq->previous_delta=ms_seq->delta; ms_seq->delta+=diff; ms_seq->init_seq=seq; ms->flags |= mflag; } } /* * Output pkt hook. Will call bound ip_masq_app specific function * called by ip_fw_masquerade(), assumes previously checked ms!=NULL * returns (new - old) skb->len diff. */ int ip_masq_app_pkt_out(struct ip_masq *ms, struct sk_buff **skb_p, struct device *dev) { struct ip_masq_app * mapp; struct iphdr *iph; struct tcphdr *th; int diff; __u32 seq; /* * check if application masquerading is bound to * this ip_masq. * assumes that once an ip_masq is bound, * it will not be unbound during its life. */ if ( (mapp = ms->app) == NULL) return 0; iph = (*skb_p)->h.iph; th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); /* * Remember seq number in case this pkt gets resized */ seq = ntohl(th->seq); /* * Fix seq stuff if flagged as so. */ if (ms->protocol == IPPROTO_TCP) { if (ms->flags & IP_MASQ_F_OUT_SEQ) masq_fix_seq(&ms->out_seq, th); if (ms->flags & IP_MASQ_F_IN_SEQ) masq_fix_ack_seq(&ms->in_seq, th); } /* * Call private output hook function */ if ( mapp->pkt_out == NULL ) return 0; diff = mapp->pkt_out(mapp, ms, skb_p, dev); /* * Update ip_masq seq stuff if len has changed. */ if (diff != 0 && ms->protocol == IPPROTO_TCP) masq_seq_update(ms, &ms->out_seq, IP_MASQ_F_OUT_SEQ, seq, diff); return diff; } /* * Input pkt hook. Will call bound ip_masq_app specific function * called by ip_fw_demasquerade(), assumes previously checked ms!=NULL. * returns (new - old) skb->len diff. */ int ip_masq_app_pkt_in(struct ip_masq *ms, struct sk_buff **skb_p, struct device *dev) { struct ip_masq_app * mapp; struct iphdr *iph; struct tcphdr *th; int diff; __u32 seq; /* * check if application masquerading is bound to * this ip_masq. * assumes that once an ip_masq is bound, * it will not be unbound during its life. */ if ( (mapp = ms->app) == NULL) return 0; iph = (*skb_p)->h.iph; th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); /* * Remember seq number in case this pkt gets resized */ seq = ntohl(th->seq); /* * Fix seq stuff if flagged as so. */ if (ms->protocol == IPPROTO_TCP) { if (ms->flags & IP_MASQ_F_IN_SEQ) masq_fix_seq(&ms->in_seq, th); if (ms->flags & IP_MASQ_F_OUT_SEQ) masq_fix_ack_seq(&ms->out_seq, th); } /* * Call private input hook function */ if ( mapp->pkt_in == NULL ) return 0; diff = mapp->pkt_in(mapp, ms, skb_p, dev); /* * Update ip_masq seq stuff if len has changed. */ if (diff != 0 && ms->protocol == IPPROTO_TCP) masq_seq_update(ms, &ms->in_seq, IP_MASQ_F_IN_SEQ, seq, diff); return diff; } /* * /proc/ip_masq_app entry function */ int ip_masq_app_getinfo(char *buffer, char **start, off_t offset, int length, int dummy) { off_t pos=0, begin=0; int len=0; struct ip_masq_app * mapp; unsigned idx; if (offset < 40) len=sprintf(buffer,"%-39s\n", "prot port n_attach name"); pos = 40; for (idx=0 ; idx < IP_MASQ_APP_TAB_SIZE; idx++) for (mapp = ip_masq_app_base[idx]; mapp ; mapp = mapp->next) { /* * If you change the length of this sprintf, then all * the length calculations need fixing too! * Line length = 40 (3 + 2 + 7 + 1 + 7 + 1 + 2 + 17) */ pos += 40; if (pos < offset) continue; len += sprintf(buffer+len, "%-3s %-7u %-7d %-17s\n", masq_proto_name(IP_MASQ_APP_PROTO(mapp->type)), IP_MASQ_APP_PORT(mapp->type), mapp->n_attach, mapp->name); if(len >= length) goto done; } done: begin = len - (pos - offset); *start = buffer + begin; len -= begin; if (len > length) len = length; return len; } /* * Initialization routine */ #ifdef CONFIG_PROC_FS static struct proc_dir_entry pde1 = { PROC_NET_IP_MASQ_APP, 11, "ip_masq_app", S_IFREG | S_IRUGO, 1, 0, 0, 0, &proc_net_inode_operations, ip_masq_app_getinfo }; #endif int ip_masq_app_init(void) { register_symtab (&ip_masq_app_syms); #ifdef CONFIG_PROC_FS proc_net_register(&pde1); #endif return 0; } /* * Replace a segment (of skb->data) with a new one. * FIXME: Should re-use same skb if space available, this could * be done if n_len < o_len, unless some extra space * were already allocated at driver level :P . */ static struct sk_buff * skb_replace(struct sk_buff *skb, int pri, char *o_buf, int o_len, char *n_buf, int n_len) { int maxsize, diff, o_offset; struct sk_buff *n_skb; int offset; maxsize = skb->truesize - sizeof(struct sk_buff); diff = n_len - o_len; o_offset = o_buf - (char*) skb->data; if (maxsize <= n_len) { if (diff != 0) { memcpy(skb->data + o_offset + n_len,o_buf + o_len, skb->len - (o_offset + o_len)); } memcpy(skb->data + o_offset, n_buf, n_len); n_skb = skb; skb->len = n_len; skb->end = skb->head+n_len; } else { /* * Sizes differ, make a copy. * * FIXME: move this to core/sbuff.c:skb_grow() */ n_skb = alloc_skb(MAX_HEADER + skb->len + diff, pri); if (n_skb == NULL) { printk("skb_replace(): no room left (from %p)\n", __builtin_return_address(0)); return skb; } n_skb->free = skb->free; skb_reserve(n_skb, MAX_HEADER); skb_put(n_skb, skb->len + diff); /* * Copy as much data from the old skb as possible. Even * though we're only forwarding packets, we need stuff * like skb->protocol (PPP driver wants it). */ offset = n_skb->data - skb->data; n_skb->h.raw = skb->h.raw + offset; n_skb->when = skb->when; n_skb->dev = skb->dev; n_skb->mac.raw = skb->mac.raw + offset; n_skb->ip_hdr = (struct iphdr *)(((char *)skb->ip_hdr)+offset); n_skb->pkt_type = skb->pkt_type; n_skb->protocol = skb->protocol; n_skb->ip_summed = skb->ip_summed; /* * Copy pkt in new buffer */ memcpy(n_skb->data, skb->data, o_offset); memcpy(n_skb->data + o_offset, n_buf, n_len); memcpy(n_skb->data + o_offset + n_len, o_buf + o_len, skb->len - (o_offset + o_len) ); /* * Problem, how to replace the new skb with old one, * preferably inplace */ kfree_skb(skb, FREE_WRITE); } return n_skb; } /* * calls skb_replace() and update ip header if new skb was allocated */ struct sk_buff * ip_masq_skb_replace(struct sk_buff *skb, int pri, char *o_buf, int o_len, char *n_buf, int n_len) { int diff; struct sk_buff *n_skb; unsigned skb_len; diff = n_len - o_len; n_skb = skb_replace(skb, pri, o_buf, o_len, n_buf, n_len); skb_len = skb->len; if (diff) { struct iphdr *iph; #if DEBUG_CONFIG_IP_MASQ_APP printk("masq_skb_replace(): pkt resized for %d bytes (len=%ld)\n", diff, skb->len); #endif /* * update ip header */ iph = n_skb->h.iph; iph->check = 0; iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); iph->tot_len = htons(skb_len + diff); } return n_skb; }
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