net/netfilter/ipvs/ip_vs_app.c

   1 /*
   2  * ip_vs_app.c: Application module support for IPVS
   3  *
   4  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
   5  *
   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.
  10  *
  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).
  14  *
  15  *              IP_MASQ_APP application masquerading module
  16  *
  17  * Author:      Juan Jose Ciarlante, <jjciarla@raiz.uncu.edu.ar>
  18  *
  19  */
  20
  21 #define KMSG_COMPONENT "IPVS"
  22 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  23
  24 #include <linux/module.h>
  25 #include <linux/kernel.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/in.h>
  28 #include <linux/ip.h>
  29 #include <linux/netfilter.h>
  30 #include <linux/slab.h>
  31 #include <net/net_namespace.h>
  32 #include <net/protocol.h>
  33 #include <net/tcp.h>
  34 #include <asm/system.h>
  35 #include <linux/stat.h>
  36 #include <linux/proc_fs.h>
  37 #include <linux/seq_file.h>
  38 #include <linux/mutex.h>
  39
  40 #include <net/ip_vs.h>
  41
  42 EXPORT_SYMBOL(register_ip_vs_app);
  43 EXPORT_SYMBOL(unregister_ip_vs_app);
  44 EXPORT_SYMBOL(register_ip_vs_app_inc);
  45
  46 static DEFINE_MUTEX(__ip_vs_app_mutex);
  47
  48 /*
  49  *      Get an ip_vs_app object
  50  */
  51 static inline int ip_vs_app_get(struct ip_vs_app *app)
  52 {
  53         return try_module_get(app->module);
  54 }
  55
  56
  57 static inline void ip_vs_app_put(struct ip_vs_app *app)
  58 {
  59         module_put(app->module);
  60 }
  61
  62
  63 /*
  64  *      Allocate/initialize app incarnation and register it in proto apps.
  65  */
  66 static int
  67 ip_vs_app_inc_new(struct net *net, struct ip_vs_app *app, __u16 proto,
  68                   __u16 port)
  69 {
  70         struct ip_vs_protocol *pp;
  71         struct ip_vs_app *inc;
  72         int ret;
  73
  74         if (!(pp = ip_vs_proto_get(proto)))
  75                 return -EPROTONOSUPPORT;
  76
  77         if (!pp->unregister_app)
  78                 return -EOPNOTSUPP;
  79
  80         inc = kmemdup(app, sizeof(*inc), GFP_KERNEL);
  81         if (!inc)
  82                 return -ENOMEM;
  83         INIT_LIST_HEAD(&inc->p_list);
  84         INIT_LIST_HEAD(&inc->incs_list);
  85         inc->app = app;
  86         inc->port = htons(port);
  87         atomic_set(&inc->usecnt, 0);
  88
  89         if (app->timeouts) {
  90                 inc->timeout_table =
  91                         ip_vs_create_timeout_table(app->timeouts,
  92                                                    app->timeouts_size);
  93                 if (!inc->timeout_table) {
  94                         ret = -ENOMEM;
  95                         goto out;
  96                 }
  97         }
  98
  99         ret = pp->register_app(net, inc);
 100         if (ret)
 101                 goto out;
 102
 103         list_add(&inc->a_list, &app->incs_list);
 104         IP_VS_DBG(9, "%s App %s:%u registered\n",
 105                   pp->name, inc->name, ntohs(inc->port));
 106
 107         return 0;
 108
 109   out:
 110         kfree(inc->timeout_table);
 111         kfree(inc);
 112         return ret;
 113 }
 114
 115
 116 /*
 117  *      Release app incarnation
 118  */
 119 static void
 120 ip_vs_app_inc_release(struct net *net, struct ip_vs_app *inc)
 121 {
 122         struct ip_vs_protocol *pp;
 123
 124         if (!(pp = ip_vs_proto_get(inc->protocol)))
 125                 return;
 126
 127         if (pp->unregister_app)
 128                 pp->unregister_app(net, inc);
 129
 130         IP_VS_DBG(9, "%s App %s:%u unregistered\n",
 131                   pp->name, inc->name, ntohs(inc->port));
 132
 133         list_del(&inc->a_list);
 134
 135         kfree(inc->timeout_table);
 136         kfree(inc);
 137 }
 138
 139
 140 /*
 141  *      Get reference to app inc (only called from softirq)
 142  *
 143  */
 144 int ip_vs_app_inc_get(struct ip_vs_app *inc)
 145 {
 146         int result;
 147
 148         atomic_inc(&inc->usecnt);
 149         if (unlikely((result = ip_vs_app_get(inc->app)) != 1))
 150                 atomic_dec(&inc->usecnt);
 151         return result;
 152 }
 153
 154
 155 /*
 156  *      Put the app inc (only called from timer or net softirq)
 157  */
 158 void ip_vs_app_inc_put(struct ip_vs_app *inc)
 159 {
 160         ip_vs_app_put(inc->app);
 161         atomic_dec(&inc->usecnt);
 162 }
 163
 164
 165 /*
 166  *      Register an application incarnation in protocol applications
 167  */
 168 int
 169 register_ip_vs_app_inc(struct net *net, struct ip_vs_app *app, __u16 proto,
 170                        __u16 port)
 171 {
 172         int result;
 173
 174         mutex_lock(&__ip_vs_app_mutex);
 175
 176         result = ip_vs_app_inc_new(net, app, proto, port);
 177
 178         mutex_unlock(&__ip_vs_app_mutex);
 179
 180         return result;
 181 }
 182
 183
 184 /*
 185  *      ip_vs_app registration routine
 186  */
 187 int register_ip_vs_app(struct net *net, struct ip_vs_app *app)
 188 {
 189         struct netns_ipvs *ipvs = net_ipvs(net);
 190         /* increase the module use count */
 191         ip_vs_use_count_inc();
 192
 193         mutex_lock(&__ip_vs_app_mutex);
 194
 195         list_add(&app->a_list, &ipvs->app_list);
 196
 197         mutex_unlock(&__ip_vs_app_mutex);
 198
 199         return 0;
 200 }
 201
 202
 203 /*
 204  *      ip_vs_app unregistration routine
 205  *      We are sure there are no app incarnations attached to services
 206  */
 207 void unregister_ip_vs_app(struct net *net, struct ip_vs_app *app)
 208 {
 209         struct ip_vs_app *inc, *nxt;
 210
 211         mutex_lock(&__ip_vs_app_mutex);
 212
 213         list_for_each_entry_safe(inc, nxt, &app->incs_list, a_list) {
 214                 ip_vs_app_inc_release(net, inc);
 215         }
 216
 217         list_del(&app->a_list);
 218
 219         mutex_unlock(&__ip_vs_app_mutex);
 220
 221         /* decrease the module use count */
 222         ip_vs_use_count_dec();
 223 }
 224
 225
 226 /*
 227  *      Bind ip_vs_conn to its ip_vs_app (called by cp constructor)
 228  */
 229 int ip_vs_bind_app(struct ip_vs_conn *cp,
 230                    struct ip_vs_protocol *pp)
 231 {
 232         return pp->app_conn_bind(cp);
 233 }
 234
 235
 236 /*
 237  *      Unbind cp from application incarnation (called by cp destructor)
 238  */
 239 void ip_vs_unbind_app(struct ip_vs_conn *cp)
 240 {
 241         struct ip_vs_app *inc = cp->app;
 242
 243         if (!inc)
 244                 return;
 245
 246         if (inc->unbind_conn)
 247                 inc->unbind_conn(inc, cp);
 248         if (inc->done_conn)
 249                 inc->done_conn(inc, cp);
 250         ip_vs_app_inc_put(inc);
 251         cp->app = NULL;
 252 }
 253
 254
 255 /*
 256  *      Fixes th->seq based on ip_vs_seq info.
 257  */
 258 static inline void vs_fix_seq(const struct ip_vs_seq *vseq, struct tcphdr *th)
 259 {
 260         __u32 seq = ntohl(th->seq);
 261
 262         /*
 263          *      Adjust seq with delta-offset for all packets after
 264          *      the most recent resized pkt seq and with previous_delta offset
 265          *      for all packets before most recent resized pkt seq.
 266          */
 267         if (vseq->delta || vseq->previous_delta) {
 268                 if(after(seq, vseq->init_seq)) {
 269                         th->seq = htonl(seq + vseq->delta);
 270                         IP_VS_DBG(9, "%s(): added delta (%d) to seq\n",
 271                                   __func__, vseq->delta);
 272                 } else {
 273                         th->seq = htonl(seq + vseq->previous_delta);
 274                         IP_VS_DBG(9, "%s(): added previous_delta (%d) to seq\n",
 275                                   __func__, vseq->previous_delta);
 276                 }
 277         }
 278 }
 279
 280
 281 /*
 282  *      Fixes th->ack_seq based on ip_vs_seq info.
 283  */
 284 static inline void
 285 vs_fix_ack_seq(const struct ip_vs_seq *vseq, struct tcphdr *th)
 286 {
 287         __u32 ack_seq = ntohl(th->ack_seq);
 288
 289         /*
 290          * Adjust ack_seq with delta-offset for
 291          * the packets AFTER most recent resized pkt has caused a shift
 292          * for packets before most recent resized pkt, use previous_delta
 293          */
 294         if (vseq->delta || vseq->previous_delta) {
 295                 /* since ack_seq is the number of octet that is expected
 296                    to receive next, so compare it with init_seq+delta */
 297                 if(after(ack_seq, vseq->init_seq+vseq->delta)) {
 298                         th->ack_seq = htonl(ack_seq - vseq->delta);
 299                         IP_VS_DBG(9, "%s(): subtracted delta "
 300                                   "(%d) from ack_seq\n", __func__, vseq->delta);
 301
 302                 } else {
 303                         th->ack_seq = htonl(ack_seq - vseq->previous_delta);
 304                         IP_VS_DBG(9, "%s(): subtracted "
 305                                   "previous_delta (%d) from ack_seq\n",
 306                                   __func__, vseq->previous_delta);
 307                 }
 308         }
 309 }
 310
 311
 312 /*
 313  *      Updates ip_vs_seq if pkt has been resized
 314  *      Assumes already checked proto==IPPROTO_TCP and diff!=0.
 315  */
 316 static inline void vs_seq_update(struct ip_vs_conn *cp, struct ip_vs_seq *vseq,
 317                                  unsigned flag, __u32 seq, int diff)
 318 {
 319         /* spinlock is to keep updating cp->flags atomic */
 320         spin_lock(&cp->lock);
 321         if (!(cp->flags & flag) || after(seq, vseq->init_seq)) {
 322                 vseq->previous_delta = vseq->delta;
 323                 vseq->delta += diff;
 324                 vseq->init_seq = seq;
 325                 cp->flags |= flag;
 326         }
 327         spin_unlock(&cp->lock);
 328 }
 329
 330 static inline int app_tcp_pkt_out(struct ip_vs_conn *cp, struct sk_buff *skb,
 331                                   struct ip_vs_app *app)
 332 {
 333         int diff;
 334         const unsigned int tcp_offset = ip_hdrlen(skb);
 335         struct tcphdr *th;
 336         __u32 seq;
 337
 338         if (!skb_make_writable(skb, tcp_offset + sizeof(*th)))
 339                 return 0;
 340
 341         th = (struct tcphdr *)(skb_network_header(skb) + tcp_offset);
 342
 343         /*
 344          *      Remember seq number in case this pkt gets resized
 345          */
 346         seq = ntohl(th->seq);
 347
 348         /*
 349          *      Fix seq stuff if flagged as so.
 350          */
 351         if (cp->flags & IP_VS_CONN_F_OUT_SEQ)
 352                 vs_fix_seq(&cp->out_seq, th);
 353         if (cp->flags & IP_VS_CONN_F_IN_SEQ)
 354                 vs_fix_ack_seq(&cp->in_seq, th);
 355
 356         /*
 357          *      Call private output hook function
 358          */
 359         if (app->pkt_out == NULL)
 360                 return 1;
 361
 362         if (!app->pkt_out(app, cp, skb, &diff))
 363                 return 0;
 364
 365         /*
 366          *      Update ip_vs seq stuff if len has changed.
 367          */
 368         if (diff != 0)
 369                 vs_seq_update(cp, &cp->out_seq,
 370                               IP_VS_CONN_F_OUT_SEQ, seq, diff);
 371
 372         return 1;
 373 }
 374
 375 /*
 376  *      Output pkt hook. Will call bound ip_vs_app specific function
 377  *      called by ipvs packet handler, assumes previously checked cp!=NULL
 378  *      returns false if it can't handle packet (oom)
 379  */
 380 int ip_vs_app_pkt_out(struct ip_vs_conn *cp, struct sk_buff *skb)
 381 {
 382         struct ip_vs_app *app;
 383
 384         /*
 385          *      check if application module is bound to
 386          *      this ip_vs_conn.
 387          */
 388         if ((app = cp->app) == NULL)
 389                 return 1;
 390
 391         /* TCP is complicated */
 392         if (cp->protocol == IPPROTO_TCP)
 393                 return app_tcp_pkt_out(cp, skb, app);
 394
 395         /*
 396          *      Call private output hook function
 397          */
 398         if (app->pkt_out == NULL)
 399                 return 1;
 400
 401         return app->pkt_out(app, cp, skb, NULL);
 402 }
 403
 404
 405 static inline int app_tcp_pkt_in(struct ip_vs_conn *cp, struct sk_buff *skb,
 406                                  struct ip_vs_app *app)
 407 {
 408         int diff;
 409         const unsigned int tcp_offset = ip_hdrlen(skb);
 410         struct tcphdr *th;
 411         __u32 seq;
 412
 413         if (!skb_make_writable(skb, tcp_offset + sizeof(*th)))
 414                 return 0;
 415
 416         th = (struct tcphdr *)(skb_network_header(skb) + tcp_offset);
 417
 418         /*
 419          *      Remember seq number in case this pkt gets resized
 420          */
 421         seq = ntohl(th->seq);
 422
 423         /*
 424          *      Fix seq stuff if flagged as so.
 425          */
 426         if (cp->flags & IP_VS_CONN_F_IN_SEQ)
 427                 vs_fix_seq(&cp->in_seq, th);
 428         if (cp->flags & IP_VS_CONN_F_OUT_SEQ)
 429                 vs_fix_ack_seq(&cp->out_seq, th);
 430
 431         /*
 432          *      Call private input hook function
 433          */
 434         if (app->pkt_in == NULL)
 435                 return 1;
 436
 437         if (!app->pkt_in(app, cp, skb, &diff))
 438                 return 0;
 439
 440         /*
 441          *      Update ip_vs seq stuff if len has changed.
 442          */
 443         if (diff != 0)
 444                 vs_seq_update(cp, &cp->in_seq,
 445                               IP_VS_CONN_F_IN_SEQ, seq, diff);
 446
 447         return 1;
 448 }
 449
 450 /*
 451  *      Input pkt hook. Will call bound ip_vs_app specific function
 452  *      called by ipvs packet handler, assumes previously checked cp!=NULL.
 453  *      returns false if can't handle packet (oom).
 454  */
 455 int ip_vs_app_pkt_in(struct ip_vs_conn *cp, struct sk_buff *skb)
 456 {
 457         struct ip_vs_app *app;
 458
 459         /*
 460          *      check if application module is bound to
 461          *      this ip_vs_conn.
 462          */
 463         if ((app = cp->app) == NULL)
 464                 return 1;
 465
 466         /* TCP is complicated */
 467         if (cp->protocol == IPPROTO_TCP)
 468                 return app_tcp_pkt_in(cp, skb, app);
 469
 470         /*
 471          *      Call private input hook function
 472          */
 473         if (app->pkt_in == NULL)
 474                 return 1;
 475
 476         return app->pkt_in(app, cp, skb, NULL);
 477 }
 478
 479
 480 #ifdef CONFIG_PROC_FS
 481 /*
 482  *      /proc/net/ip_vs_app entry function
 483  */
 484
 485 static struct ip_vs_app *ip_vs_app_idx(struct netns_ipvs *ipvs, loff_t pos)
 486 {
 487         struct ip_vs_app *app, *inc;
 488
 489         list_for_each_entry(app, &ipvs->app_list, a_list) {
 490                 list_for_each_entry(inc, &app->incs_list, a_list) {
 491                         if (pos-- == 0)
 492                                 return inc;
 493                 }
 494         }
 495         return NULL;
 496
 497 }
 498
 499 static void *ip_vs_app_seq_start(struct seq_file *seq, loff_t *pos)
 500 {
 501         struct net *net = seq_file_net(seq);
 502         struct netns_ipvs *ipvs = net_ipvs(net);
 503
 504         mutex_lock(&__ip_vs_app_mutex);
 505
 506         return *pos ? ip_vs_app_idx(ipvs, *pos - 1) : SEQ_START_TOKEN;
 507 }
 508
 509 static void *ip_vs_app_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 510 {
 511         struct ip_vs_app *inc, *app;
 512         struct list_head *e;
 513         struct net *net = seq_file_net(seq);
 514         struct netns_ipvs *ipvs = net_ipvs(net);
 515
 516         ++*pos;
 517         if (v == SEQ_START_TOKEN)
 518                 return ip_vs_app_idx(ipvs, 0);
 519
 520         inc = v;
 521         app = inc->app;
 522
 523         if ((e = inc->a_list.next) != &app->incs_list)
 524                 return list_entry(e, struct ip_vs_app, a_list);
 525
 526         /* go on to next application */
 527         for (e = app->a_list.next; e != &ipvs->app_list; e = e->next) {
 528                 app = list_entry(e, struct ip_vs_app, a_list);
 529                 list_for_each_entry(inc, &app->incs_list, a_list) {
 530                         return inc;
 531                 }
 532         }
 533         return NULL;
 534 }
 535
 536 static void ip_vs_app_seq_stop(struct seq_file *seq, void *v)
 537 {
 538         mutex_unlock(&__ip_vs_app_mutex);
 539 }
 540
 541 static int ip_vs_app_seq_show(struct seq_file *seq, void *v)
 542 {
 543         if (v == SEQ_START_TOKEN)
 544                 seq_puts(seq, "prot port    usecnt name\n");
 545         else {
 546                 const struct ip_vs_app *inc = v;
 547
 548                 seq_printf(seq, "%-3s  %-7u %-6d %-17s\n",
 549                            ip_vs_proto_name(inc->protocol),
 550                            ntohs(inc->port),
 551                            atomic_read(&inc->usecnt),
 552                            inc->name);
 553         }
 554         return 0;
 555 }
 556
 557 static const struct seq_operations ip_vs_app_seq_ops = {
 558         .start = ip_vs_app_seq_start,
 559         .next  = ip_vs_app_seq_next,
 560         .stop  = ip_vs_app_seq_stop,
 561         .show  = ip_vs_app_seq_show,
 562 };
 563
 564 static int ip_vs_app_open(struct inode *inode, struct file *file)
 565 {
 566         return seq_open_net(inode, file, &ip_vs_app_seq_ops,
 567                             sizeof(struct seq_net_private));
 568 }
 569
 570 static const struct file_operations ip_vs_app_fops = {
 571         .owner   = THIS_MODULE,
 572         .open    = ip_vs_app_open,
 573         .read    = seq_read,
 574         .llseek  = seq_lseek,
 575         .release = seq_release_net,
 576 };
 577 #endif
 578
 579 int __net_init ip_vs_app_net_init(struct net *net)
 580 {
 581         struct netns_ipvs *ipvs = net_ipvs(net);
 582
 583         INIT_LIST_HEAD(&ipvs->app_list);
 584         proc_net_fops_create(net, "ip_vs_app", 0, &ip_vs_app_fops);
 585         return 0;
 586 }
 587
 588 void __net_exit ip_vs_app_net_cleanup(struct net *net)
 589 {
 590         proc_net_remove(net, "ip_vs_app");
 591 }