2 * ip_vs_app.c: Application module support for IPVS
4 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
11 * Most code here is taken from ip_masq_app.c in kernel 2.2. The difference
12 * is that ip_vs_app module handles the reverse direction (incoming requests
13 * and outgoing responses).
15 * IP_MASQ_APP application masquerading module
17 * Author: Juan Jose Ciarlante, <jjciarla@raiz.uncu.edu.ar>
21 #define KMSG_COMPONENT "IPVS"
22 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
24 #include <linux/module.h>
25 #include <linux/kernel.h>
26 #include <linux/skbuff.h>
29 #include <linux/netfilter.h>
30 #include <net/net_namespace.h>
31 #include <net/protocol.h>
33 #include <asm/system.h>
34 #include <linux/stat.h>
35 #include <linux/proc_fs.h>
36 #include <linux/seq_file.h>
37 #include <linux/mutex.h>
39 #include <net/ip_vs.h>
41 EXPORT_SYMBOL(register_ip_vs_app);
42 EXPORT_SYMBOL(unregister_ip_vs_app);
43 EXPORT_SYMBOL(register_ip_vs_app_inc);
45 /* ipvs application list head */
46 static LIST_HEAD(ip_vs_app_list);
47 static DEFINE_MUTEX(__ip_vs_app_mutex);
51 * Get an ip_vs_app object
53 static inline int ip_vs_app_get(struct ip_vs_app *app)
55 return try_module_get(app->module);
59 static inline void ip_vs_app_put(struct ip_vs_app *app)
61 module_put(app->module);
66 * Allocate/initialize app incarnation and register it in proto apps.
69 ip_vs_app_inc_new(struct ip_vs_app *app, __u16 proto, __u16 port)
71 struct ip_vs_protocol *pp;
72 struct ip_vs_app *inc;
75 if (!(pp = ip_vs_proto_get(proto)))
76 return -EPROTONOSUPPORT;
78 if (!pp->unregister_app)
81 inc = kmemdup(app, sizeof(*inc), GFP_KERNEL);
84 INIT_LIST_HEAD(&inc->p_list);
85 INIT_LIST_HEAD(&inc->incs_list);
87 inc->port = htons(port);
88 atomic_set(&inc->usecnt, 0);
92 ip_vs_create_timeout_table(app->timeouts,
94 if (!inc->timeout_table) {
100 ret = pp->register_app(inc);
104 list_add(&inc->a_list, &app->incs_list);
105 IP_VS_DBG(9, "%s application %s:%u registered\n",
106 pp->name, inc->name, inc->port);
111 kfree(inc->timeout_table);
118 * Release app incarnation
121 ip_vs_app_inc_release(struct ip_vs_app *inc)
123 struct ip_vs_protocol *pp;
125 if (!(pp = ip_vs_proto_get(inc->protocol)))
128 if (pp->unregister_app)
129 pp->unregister_app(inc);
131 IP_VS_DBG(9, "%s App %s:%u unregistered\n",
132 pp->name, inc->name, inc->port);
134 list_del(&inc->a_list);
136 kfree(inc->timeout_table);
142 * Get reference to app inc (only called from softirq)
145 int ip_vs_app_inc_get(struct ip_vs_app *inc)
149 atomic_inc(&inc->usecnt);
150 if (unlikely((result = ip_vs_app_get(inc->app)) != 1))
151 atomic_dec(&inc->usecnt);
157 * Put the app inc (only called from timer or net softirq)
159 void ip_vs_app_inc_put(struct ip_vs_app *inc)
161 ip_vs_app_put(inc->app);
162 atomic_dec(&inc->usecnt);
167 * Register an application incarnation in protocol applications
170 register_ip_vs_app_inc(struct ip_vs_app *app, __u16 proto, __u16 port)
174 mutex_lock(&__ip_vs_app_mutex);
176 result = ip_vs_app_inc_new(app, proto, port);
178 mutex_unlock(&__ip_vs_app_mutex);
185 * ip_vs_app registration routine
187 int register_ip_vs_app(struct ip_vs_app *app)
189 /* increase the module use count */
190 ip_vs_use_count_inc();
192 mutex_lock(&__ip_vs_app_mutex);
194 list_add(&app->a_list, &ip_vs_app_list);
196 mutex_unlock(&__ip_vs_app_mutex);
203 * ip_vs_app unregistration routine
204 * We are sure there are no app incarnations attached to services
206 void unregister_ip_vs_app(struct ip_vs_app *app)
208 struct ip_vs_app *inc, *nxt;
210 mutex_lock(&__ip_vs_app_mutex);
212 list_for_each_entry_safe(inc, nxt, &app->incs_list, a_list) {
213 ip_vs_app_inc_release(inc);
216 list_del(&app->a_list);
218 mutex_unlock(&__ip_vs_app_mutex);
220 /* decrease the module use count */
221 ip_vs_use_count_dec();
226 * Bind ip_vs_conn to its ip_vs_app (called by cp constructor)
228 int ip_vs_bind_app(struct ip_vs_conn *cp, struct ip_vs_protocol *pp)
230 return pp->app_conn_bind(cp);
235 * Unbind cp from application incarnation (called by cp destructor)
237 void ip_vs_unbind_app(struct ip_vs_conn *cp)
239 struct ip_vs_app *inc = cp->app;
244 if (inc->unbind_conn)
245 inc->unbind_conn(inc, cp);
247 inc->done_conn(inc, cp);
248 ip_vs_app_inc_put(inc);
254 * Fixes th->seq based on ip_vs_seq info.
256 static inline void vs_fix_seq(const struct ip_vs_seq *vseq, struct tcphdr *th)
258 __u32 seq = ntohl(th->seq);
261 * Adjust seq with delta-offset for all packets after
262 * the most recent resized pkt seq and with previous_delta offset
263 * for all packets before most recent resized pkt seq.
265 if (vseq->delta || vseq->previous_delta) {
266 if(after(seq, vseq->init_seq)) {
267 th->seq = htonl(seq + vseq->delta);
268 IP_VS_DBG(9, "%s(): added delta (%d) to seq\n",
269 __func__, vseq->delta);
271 th->seq = htonl(seq + vseq->previous_delta);
272 IP_VS_DBG(9, "%s(): added previous_delta (%d) to seq\n",
273 __func__, vseq->previous_delta);
280 * Fixes th->ack_seq based on ip_vs_seq info.
283 vs_fix_ack_seq(const struct ip_vs_seq *vseq, struct tcphdr *th)
285 __u32 ack_seq = ntohl(th->ack_seq);
288 * Adjust ack_seq with delta-offset for
289 * the packets AFTER most recent resized pkt has caused a shift
290 * for packets before most recent resized pkt, use previous_delta
292 if (vseq->delta || vseq->previous_delta) {
293 /* since ack_seq is the number of octet that is expected
294 to receive next, so compare it with init_seq+delta */
295 if(after(ack_seq, vseq->init_seq+vseq->delta)) {
296 th->ack_seq = htonl(ack_seq - vseq->delta);
297 IP_VS_DBG(9, "%s(): subtracted delta "
298 "(%d) from ack_seq\n", __func__, vseq->delta);
301 th->ack_seq = htonl(ack_seq - vseq->previous_delta);
302 IP_VS_DBG(9, "%s(): subtracted "
303 "previous_delta (%d) from ack_seq\n",
304 __func__, vseq->previous_delta);
311 * Updates ip_vs_seq if pkt has been resized
312 * Assumes already checked proto==IPPROTO_TCP and diff!=0.
314 static inline void vs_seq_update(struct ip_vs_conn *cp, struct ip_vs_seq *vseq,
315 unsigned flag, __u32 seq, int diff)
317 /* spinlock is to keep updating cp->flags atomic */
318 spin_lock(&cp->lock);
319 if (!(cp->flags & flag) || after(seq, vseq->init_seq)) {
320 vseq->previous_delta = vseq->delta;
322 vseq->init_seq = seq;
325 spin_unlock(&cp->lock);
328 static inline int app_tcp_pkt_out(struct ip_vs_conn *cp, struct sk_buff *skb,
329 struct ip_vs_app *app)
332 const unsigned int tcp_offset = ip_hdrlen(skb);
336 if (!skb_make_writable(skb, tcp_offset + sizeof(*th)))
339 th = (struct tcphdr *)(skb_network_header(skb) + tcp_offset);
342 * Remember seq number in case this pkt gets resized
344 seq = ntohl(th->seq);
347 * Fix seq stuff if flagged as so.
349 if (cp->flags & IP_VS_CONN_F_OUT_SEQ)
350 vs_fix_seq(&cp->out_seq, th);
351 if (cp->flags & IP_VS_CONN_F_IN_SEQ)
352 vs_fix_ack_seq(&cp->in_seq, th);
355 * Call private output hook function
357 if (app->pkt_out == NULL)
360 if (!app->pkt_out(app, cp, skb, &diff))
364 * Update ip_vs seq stuff if len has changed.
367 vs_seq_update(cp, &cp->out_seq,
368 IP_VS_CONN_F_OUT_SEQ, seq, diff);
374 * Output pkt hook. Will call bound ip_vs_app specific function
375 * called by ipvs packet handler, assumes previously checked cp!=NULL
376 * returns false if it can't handle packet (oom)
378 int ip_vs_app_pkt_out(struct ip_vs_conn *cp, struct sk_buff *skb)
380 struct ip_vs_app *app;
383 * check if application module is bound to
386 if ((app = cp->app) == NULL)
389 /* TCP is complicated */
390 if (cp->protocol == IPPROTO_TCP)
391 return app_tcp_pkt_out(cp, skb, app);
394 * Call private output hook function
396 if (app->pkt_out == NULL)
399 return app->pkt_out(app, cp, skb, NULL);
403 static inline int app_tcp_pkt_in(struct ip_vs_conn *cp, struct sk_buff *skb,
404 struct ip_vs_app *app)
407 const unsigned int tcp_offset = ip_hdrlen(skb);
411 if (!skb_make_writable(skb, tcp_offset + sizeof(*th)))
414 th = (struct tcphdr *)(skb_network_header(skb) + tcp_offset);
417 * Remember seq number in case this pkt gets resized
419 seq = ntohl(th->seq);
422 * Fix seq stuff if flagged as so.
424 if (cp->flags & IP_VS_CONN_F_IN_SEQ)
425 vs_fix_seq(&cp->in_seq, th);
426 if (cp->flags & IP_VS_CONN_F_OUT_SEQ)
427 vs_fix_ack_seq(&cp->out_seq, th);
430 * Call private input hook function
432 if (app->pkt_in == NULL)
435 if (!app->pkt_in(app, cp, skb, &diff))
439 * Update ip_vs seq stuff if len has changed.
442 vs_seq_update(cp, &cp->in_seq,
443 IP_VS_CONN_F_IN_SEQ, seq, diff);
449 * Input pkt hook. Will call bound ip_vs_app specific function
450 * called by ipvs packet handler, assumes previously checked cp!=NULL.
451 * returns false if can't handle packet (oom).
453 int ip_vs_app_pkt_in(struct ip_vs_conn *cp, struct sk_buff *skb)
455 struct ip_vs_app *app;
458 * check if application module is bound to
461 if ((app = cp->app) == NULL)
464 /* TCP is complicated */
465 if (cp->protocol == IPPROTO_TCP)
466 return app_tcp_pkt_in(cp, skb, app);
469 * Call private input hook function
471 if (app->pkt_in == NULL)
474 return app->pkt_in(app, cp, skb, NULL);
478 #ifdef CONFIG_PROC_FS
480 * /proc/net/ip_vs_app entry function
483 static struct ip_vs_app *ip_vs_app_idx(loff_t pos)
485 struct ip_vs_app *app, *inc;
487 list_for_each_entry(app, &ip_vs_app_list, a_list) {
488 list_for_each_entry(inc, &app->incs_list, a_list) {
497 static void *ip_vs_app_seq_start(struct seq_file *seq, loff_t *pos)
499 mutex_lock(&__ip_vs_app_mutex);
501 return *pos ? ip_vs_app_idx(*pos - 1) : SEQ_START_TOKEN;
504 static void *ip_vs_app_seq_next(struct seq_file *seq, void *v, loff_t *pos)
506 struct ip_vs_app *inc, *app;
510 if (v == SEQ_START_TOKEN)
511 return ip_vs_app_idx(0);
516 if ((e = inc->a_list.next) != &app->incs_list)
517 return list_entry(e, struct ip_vs_app, a_list);
519 /* go on to next application */
520 for (e = app->a_list.next; e != &ip_vs_app_list; e = e->next) {
521 app = list_entry(e, struct ip_vs_app, a_list);
522 list_for_each_entry(inc, &app->incs_list, a_list) {
529 static void ip_vs_app_seq_stop(struct seq_file *seq, void *v)
531 mutex_unlock(&__ip_vs_app_mutex);
534 static int ip_vs_app_seq_show(struct seq_file *seq, void *v)
536 if (v == SEQ_START_TOKEN)
537 seq_puts(seq, "prot port usecnt name\n");
539 const struct ip_vs_app *inc = v;
541 seq_printf(seq, "%-3s %-7u %-6d %-17s\n",
542 ip_vs_proto_name(inc->protocol),
544 atomic_read(&inc->usecnt),
550 static const struct seq_operations ip_vs_app_seq_ops = {
551 .start = ip_vs_app_seq_start,
552 .next = ip_vs_app_seq_next,
553 .stop = ip_vs_app_seq_stop,
554 .show = ip_vs_app_seq_show,
557 static int ip_vs_app_open(struct inode *inode, struct file *file)
559 return seq_open(file, &ip_vs_app_seq_ops);
562 static const struct file_operations ip_vs_app_fops = {
563 .owner = THIS_MODULE,
564 .open = ip_vs_app_open,
567 .release = seq_release,
573 * Replace a segment of data with a new segment
575 int ip_vs_skb_replace(struct sk_buff *skb, gfp_t pri,
576 char *o_buf, int o_len, char *n_buf, int n_len)
584 diff = n_len - o_len;
585 o_offset = o_buf - (char *)skb->data;
586 /* The length of left data after o_buf+o_len in the skb data */
587 o_left = skb->len - (o_offset + o_len);
590 memmove(o_buf + n_len, o_buf + o_len, o_left);
591 memcpy(o_buf, n_buf, n_len);
592 skb_trim(skb, skb->len + diff);
593 } else if (diff <= skb_tailroom(skb)) {
595 memmove(o_buf + n_len, o_buf + o_len, o_left);
596 memcpy(o_buf, n_buf, n_len);
598 if (pskb_expand_head(skb, skb_headroom(skb), diff, pri))
601 memmove(skb->data + o_offset + n_len,
602 skb->data + o_offset + o_len, o_left);
603 skb_copy_to_linear_data_offset(skb, o_offset, n_buf, n_len);
606 /* must update the iph total length here */
607 ip_hdr(skb)->tot_len = htons(skb->len);
614 int __init ip_vs_app_init(void)
616 /* we will replace it with proc_net_ipvs_create() soon */
617 proc_net_fops_create(&init_net, "ip_vs_app", 0, &ip_vs_app_fops);
622 void ip_vs_app_cleanup(void)
624 proc_net_remove(&init_net, "ip_vs_app");