sys/netgraph/ng_l2tp.c

   1 /*-
   2  * Copyright (c) 2001-2002 Packet Design, LLC.
   3  * All rights reserved.
   4  *
   5  * Subject to the following obligations and disclaimer of warranty,
   6  * use and redistribution of this software, in source or object code
   7  * forms, with or without modifications are expressly permitted by
   8  * Packet Design; provided, however, that:
   9  *
  10  *    (i)  Any and all reproductions of the source or object code
  11  *         must include the copyright notice above and the following
  12  *         disclaimer of warranties; and
  13  *    (ii) No rights are granted, in any manner or form, to use
  14  *         Packet Design trademarks, including the mark "PACKET DESIGN"
  15  *         on advertising, endorsements, or otherwise except as such
  16  *         appears in the above copyright notice or in the software.
  17  *
  18  * THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND
  19  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO
  20  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING
  21  * THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED
  22  * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
  23  * OR NON-INFRINGEMENT.  PACKET DESIGN DOES NOT WARRANT, GUARANTEE,
  24  * OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS
  25  * OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,
  26  * RELIABILITY OR OTHERWISE.  IN NO EVENT SHALL PACKET DESIGN BE
  27  * LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE
  28  * OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT,
  29  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL
  30  * DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF
  31  * USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF
  32  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
  34  * THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF
  35  * THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  * Author: Archie Cobbs <archie@freebsd.org>
  38  *
  39  * $FreeBSD$
  40  */
  41
  42 /*
  43  * L2TP netgraph node type.
  44  *
  45  * This node type implements the lower layer of the
  46  * L2TP protocol as specified in RFC 2661.
  47  */
  48
  49 #include <sys/param.h>
  50 #include <sys/systm.h>
  51 #include <sys/kernel.h>
  52 #include <sys/time.h>
  53 #include <sys/conf.h>
  54 #include <sys/mbuf.h>
  55 #include <sys/malloc.h>
  56 #include <sys/errno.h>
  57 #include <sys/libkern.h>
  58
  59 #include <netgraph/ng_message.h>
  60 #include <netgraph/netgraph.h>
  61 #include <netgraph/ng_parse.h>
  62 #include <netgraph/ng_l2tp.h>
  63
  64 #ifdef NG_SEPARATE_MALLOC
  65 static MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
  66 #else
  67 #define M_NETGRAPH_L2TP M_NETGRAPH
  68 #endif
  69
  70 /* L2TP header format (first 2 bytes only) */
  71 #define L2TP_HDR_CTRL           0x8000                  /* control packet */
  72 #define L2TP_HDR_LEN            0x4000                  /* has length field */
  73 #define L2TP_HDR_SEQ            0x0800                  /* has ns, nr fields */
  74 #define L2TP_HDR_OFF            0x0200                  /* has offset field */
  75 #define L2TP_HDR_PRIO           0x0100                  /* give priority */
  76 #define L2TP_HDR_VERS_MASK      0x000f                  /* version field mask */
  77 #define L2TP_HDR_VERSION        0x0002                  /* version field */
  78
  79 /* Bits that must be zero or one in first two bytes of header */
  80 #define L2TP_CTRL_0BITS         0x030d                  /* ctrl: must be 0 */
  81 #define L2TP_CTRL_1BITS         0xc802                  /* ctrl: must be 1 */
  82 #define L2TP_DATA_0BITS         0x800d                  /* data: must be 0 */
  83 #define L2TP_DATA_1BITS         0x0002                  /* data: must be 1 */
  84
  85 /* Standard xmit ctrl and data header bits */
  86 #define L2TP_CTRL_HDR           (L2TP_HDR_CTRL | L2TP_HDR_LEN \
  87                                     | L2TP_HDR_SEQ | L2TP_HDR_VERSION)
  88 #define L2TP_DATA_HDR           (L2TP_HDR_VERSION)      /* optional: len, seq */
  89
  90 /* Some hard coded values */
  91 #define L2TP_MAX_XWIN           128                     /* my max xmit window */
  92 #define L2TP_MAX_REXMIT         5                       /* default max rexmit */
  93 #define L2TP_MAX_REXMIT_TO      30                      /* default rexmit to */
  94 #define L2TP_DELAYED_ACK        ((hz + 19) / 20)        /* delayed ack: 50 ms */
  95
  96 /* Default data sequence number configuration for new sessions */
  97 #define L2TP_CONTROL_DSEQ       1                       /* we are the lns */
  98 #define L2TP_ENABLE_DSEQ        1                       /* enable data seq # */
  99
 100 /* Compare sequence numbers using circular math */
 101 #define L2TP_SEQ_DIFF(x, y)     ((int16_t)((x) - (y)))
 102
 103 #define SESSHASHSIZE            0x0020
 104 #define SESSHASH(x)             (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
 105
 106 /* Hook private data (data session hooks only) */
 107 struct ng_l2tp_hook_private {
 108         struct ng_l2tp_sess_config      conf;   /* hook/session config */
 109         struct ng_l2tp_session_stats    stats;  /* per sessions statistics */
 110         hook_p                          hook;   /* hook reference */
 111         u_int16_t                       ns;     /* data ns sequence number */
 112         u_int16_t                       nr;     /* data nr sequence number */
 113         LIST_ENTRY(ng_l2tp_hook_private) sessions;
 114 };
 115 typedef struct ng_l2tp_hook_private *hookpriv_p;
 116
 117 /*
 118  * Sequence number state
 119  *
 120  * Invariants:
 121  *    - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
 122  *    - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
 123  *    - The first (ns - rack) mbuf's in xwin[] array are copies of these
 124  *      unacknowledged packets; the remainder of xwin[] consists first of
 125  *      zero or more further untransmitted packets in the transmit queue
 126  *    - We try to keep the peer's receive window as full as possible.
 127  *      Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
 128  *    - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
 129  *    - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
 130  *    - xack_timer is running iff xack != nr (unack'd rec'd pkts)
 131  */
 132 struct l2tp_seq {
 133         u_int16_t               ns;             /* next xmit seq we send */
 134         u_int16_t               nr;             /* next recv seq we expect */
 135         u_int16_t               inproc;         /* packet is in processing */
 136         u_int16_t               rack;           /* last 'nr' we rec'd */
 137         u_int16_t               xack;           /* last 'nr' we sent */
 138         u_int16_t               wmax;           /* peer's max recv window */
 139         u_int16_t               cwnd;           /* current congestion window */
 140         u_int16_t               ssth;           /* slow start threshold */
 141         u_int16_t               acks;           /* # consecutive acks rec'd */
 142         u_int16_t               rexmits;        /* # retransmits sent */
 143         struct callout          rack_timer;     /* retransmit timer */
 144         struct callout          xack_timer;     /* delayed ack timer */
 145         struct mbuf             *xwin[L2TP_MAX_XWIN];   /* transmit window */
 146         struct mtx              mtx;                    /* seq mutex */
 147 };
 148
 149 /* Node private data */
 150 struct ng_l2tp_private {
 151         node_p                  node;           /* back pointer to node */
 152         hook_p                  ctrl;           /* hook to upper layers */
 153         hook_p                  lower;          /* hook to lower layers */
 154         struct ng_l2tp_config   conf;           /* node configuration */
 155         struct ng_l2tp_stats    stats;          /* node statistics */
 156         struct l2tp_seq         seq;            /* ctrl sequence number state */
 157         ng_ID_t                 ftarget;        /* failure message target */
 158         LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE];
 159 };
 160 typedef struct ng_l2tp_private *priv_p;
 161
 162 /* Netgraph node methods */
 163 static ng_constructor_t ng_l2tp_constructor;
 164 static ng_rcvmsg_t      ng_l2tp_rcvmsg;
 165 static ng_shutdown_t    ng_l2tp_shutdown;
 166 static ng_newhook_t     ng_l2tp_newhook;
 167 static ng_rcvdata_t     ng_l2tp_rcvdata;
 168 static ng_rcvdata_t     ng_l2tp_rcvdata_lower;
 169 static ng_rcvdata_t     ng_l2tp_rcvdata_ctrl;
 170 static ng_disconnect_t  ng_l2tp_disconnect;
 171
 172 /* Internal functions */
 173 static int      ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
 174
 175 static void     ng_l2tp_seq_init(priv_p priv);
 176 static int      ng_l2tp_seq_set(priv_p priv,
 177                         const struct ng_l2tp_seq_config *conf);
 178 static int      ng_l2tp_seq_adjust(priv_p priv,
 179                         const struct ng_l2tp_config *conf);
 180 static void     ng_l2tp_seq_reset(priv_p priv);
 181 static void     ng_l2tp_seq_failure(priv_p priv);
 182 static void     ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
 183 static void     ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
 184                     void *arg1, int arg2);
 185 static void     ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
 186                     void *arg1, int arg2);
 187
 188 static hookpriv_p       ng_l2tp_find_session(priv_p privp, u_int16_t sid);
 189 static ng_fn_eachhook   ng_l2tp_reset_session;
 190
 191 /* Parse type for struct ng_l2tp_seq_config. */
 192 static const struct ng_parse_struct_field
 193         ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
 194 static const struct ng_parse_type ng_l2tp_seq_config_type = {
 195         &ng_parse_struct_type,
 196         &ng_l2tp_seq_config_fields
 197 };
 198
 199 /* Parse type for struct ng_l2tp_config */
 200 static const struct ng_parse_struct_field
 201         ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
 202 static const struct ng_parse_type ng_l2tp_config_type = {
 203         &ng_parse_struct_type,
 204         &ng_l2tp_config_type_fields,
 205 };
 206
 207 /* Parse type for struct ng_l2tp_sess_config */
 208 static const struct ng_parse_struct_field
 209         ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
 210 static const struct ng_parse_type ng_l2tp_sess_config_type = {
 211         &ng_parse_struct_type,
 212         &ng_l2tp_sess_config_type_fields,
 213 };
 214
 215 /* Parse type for struct ng_l2tp_stats */
 216 static const struct ng_parse_struct_field
 217         ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
 218 static const struct ng_parse_type ng_l2tp_stats_type = {
 219         &ng_parse_struct_type,
 220         &ng_l2tp_stats_type_fields
 221 };
 222
 223 /* Parse type for struct ng_l2tp_session_stats. */
 224 static const struct ng_parse_struct_field
 225         ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
 226 static const struct ng_parse_type ng_l2tp_session_stats_type = {
 227         &ng_parse_struct_type,
 228         &ng_l2tp_session_stats_type_fields
 229 };
 230
 231 /* List of commands and how to convert arguments to/from ASCII */
 232 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
 233         {
 234           NGM_L2TP_COOKIE,
 235           NGM_L2TP_SET_CONFIG,
 236           "setconfig",
 237           &ng_l2tp_config_type,
 238           NULL
 239         },
 240         {
 241           NGM_L2TP_COOKIE,
 242           NGM_L2TP_GET_CONFIG,
 243           "getconfig",
 244           NULL,
 245           &ng_l2tp_config_type
 246         },
 247         {
 248           NGM_L2TP_COOKIE,
 249           NGM_L2TP_SET_SESS_CONFIG,
 250           "setsessconfig",
 251           &ng_l2tp_sess_config_type,
 252           NULL
 253         },
 254         {
 255           NGM_L2TP_COOKIE,
 256           NGM_L2TP_GET_SESS_CONFIG,
 257           "getsessconfig",
 258           &ng_parse_hint16_type,
 259           &ng_l2tp_sess_config_type
 260         },
 261         {
 262           NGM_L2TP_COOKIE,
 263           NGM_L2TP_GET_STATS,
 264           "getstats",
 265           NULL,
 266           &ng_l2tp_stats_type
 267         },
 268         {
 269           NGM_L2TP_COOKIE,
 270           NGM_L2TP_CLR_STATS,
 271           "clrstats",
 272           NULL,
 273           NULL
 274         },
 275         {
 276           NGM_L2TP_COOKIE,
 277           NGM_L2TP_GETCLR_STATS,
 278           "getclrstats",
 279           NULL,
 280           &ng_l2tp_stats_type
 281         },
 282         {
 283           NGM_L2TP_COOKIE,
 284           NGM_L2TP_GET_SESSION_STATS,
 285           "getsessstats",
 286           &ng_parse_int16_type,
 287           &ng_l2tp_session_stats_type
 288         },
 289         {
 290           NGM_L2TP_COOKIE,
 291           NGM_L2TP_CLR_SESSION_STATS,
 292           "clrsessstats",
 293           &ng_parse_int16_type,
 294           NULL
 295         },
 296         {
 297           NGM_L2TP_COOKIE,
 298           NGM_L2TP_GETCLR_SESSION_STATS,
 299           "getclrsessstats",
 300           &ng_parse_int16_type,
 301           &ng_l2tp_session_stats_type
 302         },
 303         {
 304           NGM_L2TP_COOKIE,
 305           NGM_L2TP_ACK_FAILURE,
 306           "ackfailure",
 307           NULL,
 308           NULL
 309         },
 310         {
 311           NGM_L2TP_COOKIE,
 312           NGM_L2TP_SET_SEQ,
 313           "setsequence",
 314           &ng_l2tp_seq_config_type,
 315           NULL
 316         },
 317         { 0 }
 318 };
 319
 320 /* Node type descriptor */
 321 static struct ng_type ng_l2tp_typestruct = {
 322         .version =      NG_ABI_VERSION,
 323         .name =         NG_L2TP_NODE_TYPE,
 324         .constructor =  ng_l2tp_constructor,
 325         .rcvmsg =       ng_l2tp_rcvmsg,
 326         .shutdown =     ng_l2tp_shutdown,
 327         .newhook =      ng_l2tp_newhook,
 328         .rcvdata =      ng_l2tp_rcvdata,
 329         .disconnect =   ng_l2tp_disconnect,
 330         .cmdlist =      ng_l2tp_cmdlist,
 331 };
 332 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
 333
 334 /* Sequence number state locking & sanity checking */
 335 #ifdef INVARIANTS
 336 static void     ng_l2tp_seq_check(struct l2tp_seq *seq);
 337 #define SEQ_LOCK(seq)   do {                                    \
 338                                 mtx_lock(&(seq)->mtx);          \
 339                                 ng_l2tp_seq_check(seq);         \
 340 } while (0)
 341 #define SEQ_UNLOCK(seq) do {                                    \
 342                                 ng_l2tp_seq_check(seq);         \
 343                                 mtx_unlock(&(seq)->mtx);        \
 344 } while (0)
 345 #else
 346 #define SEQ_LOCK(seq)           mtx_lock(&(seq)->mtx)
 347 #define SEQ_UNLOCK(seq)         mtx_unlock(&(seq)->mtx)
 348 #endif
 349 #define SEQ_LOCK_ASSERT(seq)    mtx_assert(&(seq)->mtx, MA_OWNED)
 350
 351 /* Whether to use m_copypacket() or m_dup() */
 352 #define L2TP_COPY_MBUF          m_copypacket
 353
 354 #define ERROUT(x)       do { error = (x); goto done; } while (0)
 355
 356 /************************************************************************
 357                         NETGRAPH NODE STUFF
 358 ************************************************************************/
 359
 360 /*
 361  * Node type constructor
 362  */
 363 static int
 364 ng_l2tp_constructor(node_p node)
 365 {
 366         priv_p priv;
 367         int     i;
 368
 369         /* Allocate private structure */
 370         priv = malloc(sizeof(*priv), M_NETGRAPH_L2TP, M_WAITOK | M_ZERO);
 371         NG_NODE_SET_PRIVATE(node, priv);
 372         priv->node = node;
 373
 374         /* Apply a semi-reasonable default configuration */
 375         priv->conf.peer_win = 1;
 376         priv->conf.rexmit_max = L2TP_MAX_REXMIT;
 377         priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
 378
 379         /* Initialize sequence number state */
 380         ng_l2tp_seq_init(priv);
 381
 382         for (i = 0; i < SESSHASHSIZE; i++)
 383             LIST_INIT(&priv->sesshash[i]);
 384
 385         /* Done */
 386         return (0);
 387 }
 388
 389 /*
 390  * Give our OK for a hook to be added.
 391  */
 392 static int
 393 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
 394 {
 395         const priv_p priv = NG_NODE_PRIVATE(node);
 396
 397         /* Check hook name */
 398         if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
 399                 if (priv->ctrl != NULL)
 400                         return (EISCONN);
 401                 priv->ctrl = hook;
 402                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
 403         } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
 404                 if (priv->lower != NULL)
 405                         return (EISCONN);
 406                 priv->lower = hook;
 407                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
 408         } else {
 409                 static const char hexdig[16] = "0123456789abcdef";
 410                 u_int16_t session_id;
 411                 hookpriv_p hpriv;
 412                 uint16_t hash;
 413                 const char *hex;
 414                 int i;
 415                 int j;
 416
 417                 /* Parse hook name to get session ID */
 418                 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
 419                     sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
 420                         return (EINVAL);
 421                 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
 422                 for (session_id = i = 0; i < 4; i++) {
 423                         for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
 424                         if (j == 16)
 425                                 return (EINVAL);
 426                         session_id = (session_id << 4) | j;
 427                 }
 428                 if (hex[i] != '\0')
 429                         return (EINVAL);
 430
 431                 /* Create hook private structure */
 432                 hpriv = malloc(sizeof(*hpriv),
 433                     M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
 434                 if (hpriv == NULL)
 435                         return (ENOMEM);
 436                 hpriv->conf.session_id = session_id;
 437                 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
 438                 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
 439                 hpriv->hook = hook;
 440                 NG_HOOK_SET_PRIVATE(hook, hpriv);
 441                 hash = SESSHASH(hpriv->conf.session_id);
 442                 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
 443         }
 444
 445         /* Done */
 446         return (0);
 447 }
 448
 449 /*
 450  * Receive a control message.
 451  */
 452 static int
 453 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
 454 {
 455         const priv_p priv = NG_NODE_PRIVATE(node);
 456         struct ng_mesg *resp = NULL;
 457         struct ng_mesg *msg;
 458         int error = 0;
 459
 460         NGI_GET_MSG(item, msg);
 461         switch (msg->header.typecookie) {
 462         case NGM_L2TP_COOKIE:
 463                 switch (msg->header.cmd) {
 464                 case NGM_L2TP_SET_CONFIG:
 465                     {
 466                         struct ng_l2tp_config *const conf =
 467                                 (struct ng_l2tp_config *)msg->data;
 468
 469                         /* Check for invalid or illegal config */
 470                         if (msg->header.arglen != sizeof(*conf)) {
 471                                 error = EINVAL;
 472                                 break;
 473                         }
 474                         conf->enabled = !!conf->enabled;
 475                         conf->match_id = !!conf->match_id;
 476                         if (priv->conf.enabled
 477                             && ((priv->conf.tunnel_id != 0
 478                                && conf->tunnel_id != priv->conf.tunnel_id)
 479                               || ((priv->conf.peer_id != 0
 480                                && conf->peer_id != priv->conf.peer_id)))) {
 481                                 error = EBUSY;
 482                                 break;
 483                         }
 484
 485                         /* Save calling node as failure target */
 486                         priv->ftarget = NGI_RETADDR(item);
 487
 488                         /* Adjust sequence number state */
 489                         if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
 490                                 break;
 491
 492                         /* Update node's config */
 493                         priv->conf = *conf;
 494                         break;
 495                     }
 496                 case NGM_L2TP_GET_CONFIG:
 497                     {
 498                         struct ng_l2tp_config *conf;
 499
 500                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
 501                         if (resp == NULL) {
 502                                 error = ENOMEM;
 503                                 break;
 504                         }
 505                         conf = (struct ng_l2tp_config *)resp->data;
 506                         *conf = priv->conf;
 507                         break;
 508                     }
 509                 case NGM_L2TP_SET_SESS_CONFIG:
 510                     {
 511                         struct ng_l2tp_sess_config *const conf =
 512                             (struct ng_l2tp_sess_config *)msg->data;
 513                         hookpriv_p hpriv;
 514
 515                         /* Check for invalid or illegal config. */
 516                         if (msg->header.arglen != sizeof(*conf)) {
 517                                 error = EINVAL;
 518                                 break;
 519                         }
 520
 521                         /* Find matching hook */
 522                         hpriv = ng_l2tp_find_session(priv, conf->session_id);
 523                         if (hpriv == NULL) {
 524                                 error = ENOENT;
 525                                 break;
 526                         }
 527
 528                         /* Update hook's config */
 529                         hpriv->conf = *conf;
 530                         break;
 531                     }
 532                 case NGM_L2TP_GET_SESS_CONFIG:
 533                     {
 534                         struct ng_l2tp_sess_config *conf;
 535                         u_int16_t session_id;
 536                         hookpriv_p hpriv;
 537
 538                         /* Get session ID */
 539                         if (msg->header.arglen != sizeof(session_id)) {
 540                                 error = EINVAL;
 541                                 break;
 542                         }
 543                         memcpy(&session_id, msg->data, 2);
 544
 545                         /* Find matching hook */
 546                         hpriv = ng_l2tp_find_session(priv, session_id);
 547                         if (hpriv == NULL) {
 548                                 error = ENOENT;
 549                                 break;
 550                         }
 551
 552                         /* Send response */
 553                         NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
 554                         if (resp == NULL) {
 555                                 error = ENOMEM;
 556                                 break;
 557                         }
 558                         conf = (struct ng_l2tp_sess_config *)resp->data;
 559                         *conf = hpriv->conf;
 560                         break;
 561                     }
 562                 case NGM_L2TP_GET_STATS:
 563                 case NGM_L2TP_CLR_STATS:
 564                 case NGM_L2TP_GETCLR_STATS:
 565                     {
 566                         if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
 567                                 NG_MKRESPONSE(resp, msg,
 568                                     sizeof(priv->stats), M_NOWAIT);
 569                                 if (resp == NULL) {
 570                                         error = ENOMEM;
 571                                         break;
 572                                 }
 573                                 memcpy(resp->data,
 574                                     &priv->stats, sizeof(priv->stats));
 575                         }
 576                         if (msg->header.cmd != NGM_L2TP_GET_STATS)
 577                                 memset(&priv->stats, 0, sizeof(priv->stats));
 578                         break;
 579                     }
 580                 case NGM_L2TP_GET_SESSION_STATS:
 581                 case NGM_L2TP_CLR_SESSION_STATS:
 582                 case NGM_L2TP_GETCLR_SESSION_STATS:
 583                     {
 584                         uint16_t session_id;
 585                         hookpriv_p hpriv;
 586
 587                         /* Get session ID. */
 588                         if (msg->header.arglen != sizeof(session_id)) {
 589                                 error = EINVAL;
 590                                 break;
 591                         }
 592                         bcopy(msg->data, &session_id, sizeof(uint16_t));
 593
 594                         /* Find matching hook. */
 595                         hpriv = ng_l2tp_find_session(priv, session_id);
 596                         if (hpriv == NULL) {
 597                                 error = ENOENT;
 598                                 break;
 599                         }
 600
 601                         if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
 602                                 NG_MKRESPONSE(resp, msg,
 603                                     sizeof(hpriv->stats), M_NOWAIT);
 604                                 if (resp == NULL) {
 605                                         error = ENOMEM;
 606                                         break;
 607                                 }
 608                                 bcopy(&hpriv->stats, resp->data,
 609                                         sizeof(hpriv->stats));
 610                         }
 611                         if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
 612                                 bzero(&hpriv->stats, sizeof(hpriv->stats));
 613                         break;
 614                     }
 615                 case NGM_L2TP_SET_SEQ:
 616                     {
 617                         struct ng_l2tp_seq_config *const conf =
 618                                 (struct ng_l2tp_seq_config *)msg->data;
 619
 620                         /* Check for invalid or illegal seq config. */
 621                         if (msg->header.arglen != sizeof(*conf)) {
 622                                 error = EINVAL;
 623                                 break;
 624                         }
 625                         conf->ns = htons(conf->ns);
 626                         conf->nr = htons(conf->nr);
 627                         conf->rack = htons(conf->rack);
 628                         conf->xack = htons(conf->xack);
 629
 630                         /* Set sequence numbers. */
 631                         error = ng_l2tp_seq_set(priv, conf);
 632                         break;
 633                     }
 634                 default:
 635                         error = EINVAL;
 636                         break;
 637                 }
 638                 break;
 639         default:
 640                 error = EINVAL;
 641                 break;
 642         }
 643
 644         /* Done */
 645         NG_RESPOND_MSG(error, node, item, resp);
 646         NG_FREE_MSG(msg);
 647         return (error);
 648 }
 649
 650 /*
 651  * Destroy node
 652  */
 653 static int
 654 ng_l2tp_shutdown(node_p node)
 655 {
 656         const priv_p priv = NG_NODE_PRIVATE(node);
 657         struct l2tp_seq *const seq = &priv->seq;
 658
 659         /* Reset sequence number state */
 660         SEQ_LOCK(seq);
 661         ng_l2tp_seq_reset(priv);
 662         SEQ_UNLOCK(seq);
 663
 664         /* Free private data if neither timer is running */
 665         ng_uncallout(&seq->rack_timer, node);
 666         ng_uncallout(&seq->xack_timer, node);
 667
 668         mtx_destroy(&seq->mtx);
 669
 670         free(priv, M_NETGRAPH_L2TP);
 671
 672         /* Unref node */
 673         NG_NODE_UNREF(node);
 674         return (0);
 675 }
 676
 677 /*
 678  * Hook disconnection
 679  */
 680 static int
 681 ng_l2tp_disconnect(hook_p hook)
 682 {
 683         const node_p node = NG_HOOK_NODE(hook);
 684         const priv_p priv = NG_NODE_PRIVATE(node);
 685
 686         /* Zero out hook pointer */
 687         if (hook == priv->ctrl)
 688                 priv->ctrl = NULL;
 689         else if (hook == priv->lower)
 690                 priv->lower = NULL;
 691         else {
 692                 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 693                 LIST_REMOVE(hpriv, sessions);
 694                 free(hpriv, M_NETGRAPH_L2TP);
 695                 NG_HOOK_SET_PRIVATE(hook, NULL);
 696         }
 697
 698         /* Go away if no longer connected to anything */
 699         if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
 700                 ng_rmnode_self(node);
 701         return (0);
 702 }
 703
 704 /*************************************************************************
 705                         INTERNAL FUNCTIONS
 706 *************************************************************************/
 707
 708 /*
 709  * Find the hook with a given session ID.
 710  */
 711 static hookpriv_p
 712 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
 713 {
 714         uint16_t        hash = SESSHASH(sid);
 715         hookpriv_p      hpriv = NULL;
 716
 717         LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
 718                 if (hpriv->conf.session_id == sid)
 719                         break;
 720         }
 721
 722         return (hpriv);
 723 }
 724
 725 /*
 726  * Reset a hook's session state.
 727  */
 728 static int
 729 ng_l2tp_reset_session(hook_p hook, void *arg)
 730 {
 731         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 732
 733         if (hpriv != NULL) {
 734                 hpriv->conf.control_dseq = 0;
 735                 hpriv->conf.enable_dseq = 0;
 736                 bzero(&hpriv->stats, sizeof(struct ng_l2tp_session_stats));
 737                 hpriv->nr = 0;
 738                 hpriv->ns = 0;
 739         }
 740         return (-1);
 741 }
 742
 743 /*
 744  * Handle an incoming frame from below.
 745  */
 746 static int
 747 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
 748 {
 749         static const u_int16_t req_bits[2][2] = {
 750                 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
 751                 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
 752         };
 753         const node_p node = NG_HOOK_NODE(h);
 754         const priv_p priv = NG_NODE_PRIVATE(node);
 755         hookpriv_p hpriv = NULL;
 756         hook_p hook = NULL;
 757         struct mbuf *m;
 758         u_int16_t tid, sid;
 759         u_int16_t hdr;
 760         u_int16_t ns, nr;
 761         int is_ctrl;
 762         int error;
 763         int len, plen;
 764
 765         /* If not configured, reject */
 766         if (!priv->conf.enabled) {
 767                 NG_FREE_ITEM(item);
 768                 ERROUT(ENXIO);
 769         }
 770
 771         /* Grab mbuf */
 772         NGI_GET_M(item, m);
 773
 774         /* Remember full packet length; needed for per session accounting. */
 775         plen = m->m_pkthdr.len;
 776
 777         /* Update stats */
 778         priv->stats.recvPackets++;
 779         priv->stats.recvOctets += plen;
 780
 781         /* Get initial header */
 782         if (m->m_pkthdr.len < 6) {
 783                 priv->stats.recvRunts++;
 784                 NG_FREE_ITEM(item);
 785                 NG_FREE_M(m);
 786                 ERROUT(EINVAL);
 787         }
 788         if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 789                 priv->stats.memoryFailures++;
 790                 NG_FREE_ITEM(item);
 791                 ERROUT(EINVAL);
 792         }
 793         hdr = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1];
 794         m_adj(m, 2);
 795
 796         /* Check required header bits and minimum length */
 797         is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
 798         if ((hdr & req_bits[is_ctrl][0]) != 0
 799             || (~hdr & req_bits[is_ctrl][1]) != 0) {
 800                 priv->stats.recvInvalid++;
 801                 NG_FREE_ITEM(item);
 802                 NG_FREE_M(m);
 803                 ERROUT(EINVAL);
 804         }
 805         if (m->m_pkthdr.len < 4                         /* tunnel, session id */
 806             + (2 * ((hdr & L2TP_HDR_LEN) != 0))         /* length field */
 807             + (4 * ((hdr & L2TP_HDR_SEQ) != 0))         /* seq # fields */
 808             + (2 * ((hdr & L2TP_HDR_OFF) != 0))) {      /* offset field */
 809                 priv->stats.recvRunts++;
 810                 NG_FREE_ITEM(item);
 811                 NG_FREE_M(m);
 812                 ERROUT(EINVAL);
 813         }
 814
 815         /* Get and validate length field if present */
 816         if ((hdr & L2TP_HDR_LEN) != 0) {
 817                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 818                         priv->stats.memoryFailures++;
 819                         NG_FREE_ITEM(item);
 820                         ERROUT(EINVAL);
 821                 }
 822                 len = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1] - 4;
 823                 m_adj(m, 2);
 824                 if (len < 0 || len > m->m_pkthdr.len) {
 825                         priv->stats.recvInvalid++;
 826                         NG_FREE_ITEM(item);
 827                         NG_FREE_M(m);
 828                         ERROUT(EINVAL);
 829                 }
 830                 if (len < m->m_pkthdr.len)              /* trim extra bytes */
 831                         m_adj(m, -(m->m_pkthdr.len - len));
 832         }
 833
 834         /* Get tunnel ID and session ID */
 835         if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 836                 priv->stats.memoryFailures++;
 837                 NG_FREE_ITEM(item);
 838                 ERROUT(EINVAL);
 839         }
 840         tid = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 841         sid = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
 842         m_adj(m, 4);
 843
 844         /* Check tunnel ID */
 845         if (tid != priv->conf.tunnel_id &&
 846             (priv->conf.match_id || tid != 0)) {
 847                 priv->stats.recvWrongTunnel++;
 848                 NG_FREE_ITEM(item);
 849                 NG_FREE_M(m);
 850                 ERROUT(EADDRNOTAVAIL);
 851         }
 852
 853         /* Check session ID (for data packets only) */
 854         if ((hdr & L2TP_HDR_CTRL) == 0) {
 855                 hpriv = ng_l2tp_find_session(priv, sid);
 856                 if (hpriv == NULL) {
 857                         priv->stats.recvUnknownSID++;
 858                         NG_FREE_ITEM(item);
 859                         NG_FREE_M(m);
 860                         ERROUT(ENOTCONN);
 861                 }
 862                 hook = hpriv->hook;
 863         }
 864
 865         /* Get Ns, Nr fields if present */
 866         if ((hdr & L2TP_HDR_SEQ) != 0) {
 867                 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 868                         priv->stats.memoryFailures++;
 869                         NG_FREE_ITEM(item);
 870                         ERROUT(EINVAL);
 871                 }
 872                 ns = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 873                 nr = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
 874                 m_adj(m, 4);
 875         } else
 876                 ns = nr = 0;
 877
 878         /* Strip offset padding if present */
 879         if ((hdr & L2TP_HDR_OFF) != 0) {
 880                 u_int16_t offset;
 881
 882                 /* Get length of offset padding */
 883                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 884                         priv->stats.memoryFailures++;
 885                         NG_FREE_ITEM(item);
 886                         ERROUT(EINVAL);
 887                 }
 888                 offset = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 889
 890                 /* Trim offset padding */
 891                 if ((2+offset) > m->m_pkthdr.len) {
 892                         priv->stats.recvInvalid++;
 893                         NG_FREE_ITEM(item);
 894                         NG_FREE_M(m);
 895                         ERROUT(EINVAL);
 896                 }
 897                 m_adj(m, 2+offset);
 898         }
 899
 900         /* Handle control packets */
 901         if ((hdr & L2TP_HDR_CTRL) != 0) {
 902                 struct l2tp_seq *const seq = &priv->seq;
 903
 904                 SEQ_LOCK(seq);
 905
 906                 /* Handle receive ack sequence number Nr */
 907                 ng_l2tp_seq_recv_nr(priv, nr);
 908
 909                 /* Discard ZLB packets */
 910                 if (m->m_pkthdr.len == 0) {
 911                         SEQ_UNLOCK(seq);
 912                         priv->stats.recvZLBs++;
 913                         NG_FREE_ITEM(item);
 914                         NG_FREE_M(m);
 915                         ERROUT(0);
 916                 }
 917
 918                 /*
 919                  * If not what we expect or we are busy, drop packet and
 920                  * send an immediate ZLB ack.
 921                  */
 922                 if (ns != seq->nr || seq->inproc) {
 923                         if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
 924                                 priv->stats.recvDuplicates++;
 925                         else
 926                                 priv->stats.recvOutOfOrder++;
 927                         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
 928                         NG_FREE_ITEM(item);
 929                         NG_FREE_M(m);
 930                         ERROUT(0);
 931                 }
 932
 933                 /* Prepend session ID to packet. */
 934                 M_PREPEND(m, 2, M_NOWAIT);
 935                 if (m == NULL) {
 936                         SEQ_UNLOCK(seq);
 937                         priv->stats.memoryFailures++;
 938                         NG_FREE_ITEM(item);
 939                         ERROUT(ENOBUFS);
 940                 }
 941                 mtod(m, u_int8_t *)[0] = sid >> 8;
 942                 mtod(m, u_int8_t *)[1] = sid & 0xff;
 943
 944                 /*
 945                  * Until we deliver this packet we can't receive next one as
 946                  * we have no information for sending ack.
 947                  */
 948                 seq->inproc = 1;
 949                 SEQ_UNLOCK(seq);
 950
 951                 /* Deliver packet to upper layers */
 952                 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
 953
 954                 SEQ_LOCK(seq);
 955                 /* Ready to process next packet. */
 956                 seq->inproc = 0;
 957
 958                 /* If packet was successfully delivered send ack. */
 959                 if (error == 0) {
 960                         /* Update recv sequence number */
 961                         seq->nr++;
 962                         /* Start receive ack timer, if not already running */
 963                         if (!callout_active(&seq->xack_timer)) {
 964                                 ng_callout(&seq->xack_timer, priv->node, NULL,
 965                                     L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
 966                                     NULL, 0);
 967                         }
 968                 }
 969                 SEQ_UNLOCK(seq);
 970
 971                 ERROUT(error);
 972         }
 973
 974         /* Per session packet, account it. */
 975         hpriv->stats.recvPackets++;
 976         hpriv->stats.recvOctets += plen;
 977
 978         /* Follow peer's lead in data sequencing, if configured to do so */
 979         if (!hpriv->conf.control_dseq)
 980                 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
 981
 982         /* Handle data sequence numbers if present and enabled */
 983         if ((hdr & L2TP_HDR_SEQ) != 0) {
 984                 if (hpriv->conf.enable_dseq
 985                     && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
 986                         NG_FREE_ITEM(item);     /* duplicate or out of order */
 987                         NG_FREE_M(m);
 988                         priv->stats.recvDataDrops++;
 989                         ERROUT(0);
 990                 }
 991                 hpriv->nr = ns + 1;
 992         }
 993
 994         /* Drop empty data packets */
 995         if (m->m_pkthdr.len == 0) {
 996                 NG_FREE_ITEM(item);
 997                 NG_FREE_M(m);
 998                 ERROUT(0);
 999         }
1000
1001         /* Deliver data */
1002         NG_FWD_NEW_DATA(error, item, hook, m);
1003 done:
1004         return (error);
1005 }
1006
1007 /*
1008  * Handle an outgoing control frame.
1009  */
1010 static int
1011 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1012 {
1013         const node_p node = NG_HOOK_NODE(hook);
1014         const priv_p priv = NG_NODE_PRIVATE(node);
1015         struct l2tp_seq *const seq = &priv->seq;
1016         struct mbuf *m;
1017         int error;
1018         int i;
1019         u_int16_t       ns;
1020
1021         /* If not configured, reject */
1022         if (!priv->conf.enabled) {
1023                 NG_FREE_ITEM(item);
1024                 ERROUT(ENXIO);
1025         }
1026
1027         /* Grab mbuf and discard other stuff XXX */
1028         NGI_GET_M(item, m);
1029         NG_FREE_ITEM(item);
1030
1031         /* Packet should have session ID prepended */
1032         if (m->m_pkthdr.len < 2) {
1033                 priv->stats.xmitInvalid++;
1034                 m_freem(m);
1035                 ERROUT(EINVAL);
1036         }
1037
1038         /* Check max length */
1039         if (m->m_pkthdr.len >= 0x10000 - 14) {
1040                 priv->stats.xmitTooBig++;
1041                 m_freem(m);
1042                 ERROUT(EOVERFLOW);
1043         }
1044
1045         SEQ_LOCK(seq);
1046
1047         /* Find next empty slot in transmit queue */
1048         for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1049         if (i == L2TP_MAX_XWIN) {
1050                 SEQ_UNLOCK(seq);
1051                 priv->stats.xmitDrops++;
1052                 m_freem(m);
1053                 ERROUT(ENOBUFS);
1054         }
1055         seq->xwin[i] = m;
1056
1057         /* If peer's receive window is already full, nothing else to do */
1058         if (i >= seq->cwnd) {
1059                 SEQ_UNLOCK(seq);
1060                 ERROUT(0);
1061         }
1062
1063         /* Start retransmit timer if not already running */
1064         if (!callout_active(&seq->rack_timer))
1065                 ng_callout(&seq->rack_timer, node, NULL,
1066                     hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1067
1068         ns = seq->ns++;
1069
1070         /* Copy packet */
1071         if ((m = L2TP_COPY_MBUF(m, M_NOWAIT)) == NULL) {
1072                 SEQ_UNLOCK(seq);
1073                 priv->stats.memoryFailures++;
1074                 ERROUT(ENOBUFS);
1075         }
1076
1077         /* Send packet and increment xmit sequence number */
1078         error = ng_l2tp_xmit_ctrl(priv, m, ns);
1079 done:
1080         return (error);
1081 }
1082
1083 /*
1084  * Handle an outgoing data frame.
1085  */
1086 static int
1087 ng_l2tp_rcvdata(hook_p hook, item_p item)
1088 {
1089         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1090         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1091         struct mbuf *m;
1092         uint8_t *p;
1093         u_int16_t hdr;
1094         int error;
1095         int i = 2;
1096
1097         /* If not configured, reject */
1098         if (!priv->conf.enabled) {
1099                 NG_FREE_ITEM(item);
1100                 ERROUT(ENXIO);
1101         }
1102
1103         /* Get mbuf */
1104         NGI_GET_M(item, m);
1105
1106         /* Check max length */
1107         if (m->m_pkthdr.len >= 0x10000 - 12) {
1108                 priv->stats.xmitDataTooBig++;
1109                 NG_FREE_ITEM(item);
1110                 NG_FREE_M(m);
1111                 ERROUT(EOVERFLOW);
1112         }
1113
1114         /* Prepend L2TP header */
1115         M_PREPEND(m, 6
1116             + (2 * (hpriv->conf.include_length != 0))
1117             + (4 * (hpriv->conf.enable_dseq != 0)),
1118             M_NOWAIT);
1119         if (m == NULL) {
1120                 priv->stats.memoryFailures++;
1121                 NG_FREE_ITEM(item);
1122                 ERROUT(ENOBUFS);
1123         }
1124         p = mtod(m, uint8_t *);
1125         hdr = L2TP_DATA_HDR;
1126         if (hpriv->conf.include_length) {
1127                 hdr |= L2TP_HDR_LEN;
1128                 p[i++] = m->m_pkthdr.len >> 8;
1129                 p[i++] = m->m_pkthdr.len & 0xff;
1130         }
1131         p[i++] = priv->conf.peer_id >> 8;
1132         p[i++] = priv->conf.peer_id & 0xff;
1133         p[i++] = hpriv->conf.peer_id >> 8;
1134         p[i++] = hpriv->conf.peer_id & 0xff;
1135         if (hpriv->conf.enable_dseq) {
1136                 hdr |= L2TP_HDR_SEQ;
1137                 p[i++] = hpriv->ns >> 8;
1138                 p[i++] = hpriv->ns & 0xff;
1139                 p[i++] = hpriv->nr >> 8;
1140                 p[i++] = hpriv->nr & 0xff;
1141                 hpriv->ns++;
1142         }
1143         p[0] = hdr >> 8;
1144         p[1] = hdr & 0xff;
1145
1146         /* Update per session stats. */
1147         hpriv->stats.xmitPackets++;
1148         hpriv->stats.xmitOctets += m->m_pkthdr.len;
1149
1150         /* And the global one. */
1151         priv->stats.xmitPackets++;
1152         priv->stats.xmitOctets += m->m_pkthdr.len;
1153
1154         /* Send packet */
1155         NG_FWD_NEW_DATA(error, item, priv->lower, m);
1156 done:
1157         return (error);
1158 }
1159
1160 /*
1161  * Send a message to our controlling node that we've failed.
1162  */
1163 static void
1164 ng_l2tp_seq_failure(priv_p priv)
1165 {
1166         struct ng_mesg *msg;
1167         int error;
1168
1169         NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1170         if (msg == NULL)
1171                 return;
1172         NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1173 }
1174
1175 /************************************************************************
1176                         SEQUENCE NUMBER HANDLING
1177 ************************************************************************/
1178
1179 /*
1180  * Initialize sequence number state.
1181  */
1182 static void
1183 ng_l2tp_seq_init(priv_p priv)
1184 {
1185         struct l2tp_seq *const seq = &priv->seq;
1186
1187         KASSERT(priv->conf.peer_win >= 1,
1188             ("%s: peer_win is zero", __func__));
1189         memset(seq, 0, sizeof(*seq));
1190         seq->cwnd = 1;
1191         seq->wmax = priv->conf.peer_win;
1192         if (seq->wmax > L2TP_MAX_XWIN)
1193                 seq->wmax = L2TP_MAX_XWIN;
1194         seq->ssth = seq->wmax;
1195         ng_callout_init(&seq->rack_timer);
1196         ng_callout_init(&seq->xack_timer);
1197         mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1198 }
1199
1200 /*
1201  * Set sequence number state as given from user.
1202  */
1203 static int
1204 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1205 {
1206         struct l2tp_seq *const seq = &priv->seq;
1207
1208         /* If node is enabled, deny update to sequence numbers. */
1209         if (priv->conf.enabled)
1210                 return (EBUSY);
1211
1212         /* We only can handle the simple cases. */
1213         if (conf->xack != conf->nr || conf->ns != conf->rack)
1214                 return (EINVAL);
1215
1216         /* Set ns,nr,rack,xack parameters. */
1217         seq->ns = conf->ns;
1218         seq->nr = conf->nr;
1219         seq->rack = conf->rack;
1220         seq->xack = conf->xack;
1221
1222         return (0);
1223 }
1224
1225 /*
1226  * Adjust sequence number state accordingly after reconfiguration.
1227  */
1228 static int
1229 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1230 {
1231         struct l2tp_seq *const seq = &priv->seq;
1232         u_int16_t new_wmax;
1233         int error = 0;
1234
1235         SEQ_LOCK(seq);
1236         /* If disabling node, reset state sequence number */
1237         if (!conf->enabled) {
1238                 ng_l2tp_seq_reset(priv);
1239                 SEQ_UNLOCK(seq);
1240                 return (0);
1241         }
1242
1243         /* Adjust peer's max recv window; it can only increase */
1244         new_wmax = conf->peer_win;
1245         if (new_wmax > L2TP_MAX_XWIN)
1246                 new_wmax = L2TP_MAX_XWIN;
1247         if (new_wmax == 0)
1248                 ERROUT(EINVAL);
1249         if (new_wmax < seq->wmax)
1250                 ERROUT(EBUSY);
1251         seq->wmax = new_wmax;
1252
1253 done:
1254         SEQ_UNLOCK(seq);
1255         return (error);
1256 }
1257
1258 /*
1259  * Reset sequence number state.
1260  */
1261 static void
1262 ng_l2tp_seq_reset(priv_p priv)
1263 {
1264         struct l2tp_seq *const seq = &priv->seq;
1265         hook_p hook;
1266         int i;
1267
1268         SEQ_LOCK_ASSERT(seq);
1269
1270         /* Stop timers */
1271         ng_uncallout(&seq->rack_timer, priv->node);
1272         ng_uncallout(&seq->xack_timer, priv->node);
1273
1274         /* Free retransmit queue */
1275         for (i = 0; i < L2TP_MAX_XWIN; i++) {
1276                 if (seq->xwin[i] == NULL)
1277                         break;
1278                 m_freem(seq->xwin[i]);
1279         }
1280
1281         /* Reset session hooks' sequence number states */
1282         NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1283
1284         /* Reset node's sequence number state */
1285         seq->ns = 0;
1286         seq->nr = 0;
1287         seq->rack = 0;
1288         seq->xack = 0;
1289         seq->wmax = L2TP_MAX_XWIN;
1290         seq->cwnd = 1;
1291         seq->ssth = seq->wmax;
1292         seq->acks = 0;
1293         seq->rexmits = 0;
1294         bzero(seq->xwin, sizeof(seq->xwin));
1295 }
1296
1297 /*
1298  * Handle receipt of an acknowledgement value (Nr) from peer.
1299  */
1300 static void
1301 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1302 {
1303         struct l2tp_seq *const seq = &priv->seq;
1304         struct mbuf     *xwin[L2TP_MAX_XWIN];   /* partial local copy */
1305         int             nack;
1306         int             i, j;
1307         uint16_t        ns;
1308
1309         SEQ_LOCK_ASSERT(seq);
1310
1311         /* Verify peer's ACK is in range */
1312         if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0)
1313                 return;                         /* duplicate ack */
1314         if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1315                 priv->stats.recvBadAcks++;      /* ack for packet not sent */
1316                 return;
1317         }
1318         KASSERT(nack <= L2TP_MAX_XWIN,
1319             ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1320
1321         /* Update receive ack stats */
1322         seq->rack = nr;
1323         seq->rexmits = 0;
1324
1325         /* Free acknowledged packets and shift up packets in the xmit queue */
1326         for (i = 0; i < nack; i++)
1327                 m_freem(seq->xwin[i]);
1328         memmove(seq->xwin, seq->xwin + nack,
1329             (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1330         memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1331             nack * sizeof(*seq->xwin));
1332
1333         /*
1334          * Do slow-start/congestion avoidance windowing algorithm described
1335          * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1336          * ACK had arrived separately.
1337          */
1338         if (seq->cwnd < seq->wmax) {
1339                 /* Handle slow start phase */
1340                 if (seq->cwnd < seq->ssth) {
1341                         seq->cwnd += nack;
1342                         nack = 0;
1343                         if (seq->cwnd > seq->ssth) {    /* into cg.av. phase */
1344                                 nack = seq->cwnd - seq->ssth;
1345                                 seq->cwnd = seq->ssth;
1346                         }
1347                 }
1348
1349                 /* Handle congestion avoidance phase */
1350                 if (seq->cwnd >= seq->ssth) {
1351                         seq->acks += nack;
1352                         while (seq->acks >= seq->cwnd) {
1353                                 seq->acks -= seq->cwnd;
1354                                 if (seq->cwnd < seq->wmax)
1355                                         seq->cwnd++;
1356                         }
1357                 }
1358         }
1359
1360         /* Stop xmit timer */
1361         if (callout_active(&seq->rack_timer))
1362                 ng_uncallout(&seq->rack_timer, priv->node);
1363
1364         /* If transmit queue is empty, we're done for now */
1365         if (seq->xwin[0] == NULL)
1366                 return;
1367
1368         /* Start restransmit timer again */
1369         ng_callout(&seq->rack_timer, priv->node, NULL,
1370             hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1371
1372         /*
1373          * Send more packets, trying to keep peer's receive window full.
1374          * Make copy of everything we need before lock release.
1375          */
1376         ns = seq->ns;
1377         j = 0;
1378         while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1379             && seq->xwin[i] != NULL) {
1380                 xwin[j++] = seq->xwin[i];
1381                 seq->ns++;
1382         }
1383
1384         /*
1385          * Send prepared.
1386          * If there is a memory error, pretend packet was sent, as it
1387          * will get retransmitted later anyway.
1388          */
1389         for (i = 0; i < j; i++) {
1390                 struct mbuf     *m;
1391                 if ((m = L2TP_COPY_MBUF(xwin[i], M_NOWAIT)) == NULL)
1392                         priv->stats.memoryFailures++;
1393                 else {
1394                         ng_l2tp_xmit_ctrl(priv, m, ns);
1395                         SEQ_LOCK(seq);
1396                 }
1397                 ns++;
1398         }
1399 }
1400
1401 /*
1402  * Handle an ack timeout. We have an outstanding ack that we
1403  * were hoping to piggy-back, but haven't, so send a ZLB.
1404  */
1405 static void
1406 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1407 {
1408         const priv_p priv = NG_NODE_PRIVATE(node);
1409         struct l2tp_seq *const seq = &priv->seq;
1410
1411         /* Make sure callout is still active before doing anything */
1412         if (callout_pending(&seq->xack_timer) ||
1413             (!callout_active(&seq->xack_timer)))
1414                 return;
1415
1416         SEQ_LOCK(seq);
1417
1418         /* Send a ZLB */
1419         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1420
1421         /* callout_deactivate() is not needed here
1422             as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1423 }
1424
1425 /*
1426  * Handle a transmit timeout. The peer has failed to respond
1427  * with an ack for our packet, so retransmit it.
1428  */
1429 static void
1430 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1431 {
1432         const priv_p priv = NG_NODE_PRIVATE(node);
1433         struct l2tp_seq *const seq = &priv->seq;
1434         struct mbuf *m;
1435         u_int delay;
1436
1437         SEQ_LOCK(seq);
1438
1439         /* Make sure callout is still active before doing anything */
1440         if (callout_pending(&seq->rack_timer) ||
1441             !callout_active(&seq->rack_timer)) {
1442                 SEQ_UNLOCK(seq);
1443                 return;
1444         }
1445
1446         priv->stats.xmitRetransmits++;
1447
1448         /* Have we reached the retransmit limit? If so, notify owner. */
1449         if (seq->rexmits++ >= priv->conf.rexmit_max)
1450                 ng_l2tp_seq_failure(priv);
1451
1452         /* Restart timer, this time with an increased delay */
1453         delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1454         if (delay > priv->conf.rexmit_max_to)
1455                 delay = priv->conf.rexmit_max_to;
1456         ng_callout(&seq->rack_timer, node, NULL,
1457             hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1458
1459         /* Do slow-start/congestion algorithm windowing algorithm */
1460         seq->ns = seq->rack;
1461         seq->ssth = (seq->cwnd + 1) / 2;
1462         seq->cwnd = 1;
1463         seq->acks = 0;
1464
1465         /* Retransmit oldest unack'd packet */
1466         m = L2TP_COPY_MBUF(seq->xwin[0], M_NOWAIT);
1467         if (m == NULL) {
1468                 SEQ_UNLOCK(seq);
1469                 priv->stats.memoryFailures++;
1470         } else
1471                 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1472
1473         /* callout_deactivate() is not needed here
1474             as ng_callout() is getting called each time */
1475 }
1476
1477 /*
1478  * Transmit a control stream packet, payload optional.
1479  * The transmit sequence number is not incremented.
1480  * Requires seq lock, returns unlocked.
1481  */
1482 static int
1483 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1484 {
1485         struct l2tp_seq *const seq = &priv->seq;
1486         uint8_t *p;
1487         uint16_t nr, session_id = 0;
1488         int error;
1489
1490         SEQ_LOCK_ASSERT(seq);
1491
1492         /* Stop ack timer: we're sending an ack with this packet.
1493            Doing this before to keep state predictable after error. */
1494         if (callout_active(&seq->xack_timer))
1495                 ng_uncallout(&seq->xack_timer, priv->node);
1496
1497         nr = seq->xack = seq->nr;
1498
1499         SEQ_UNLOCK(seq);
1500
1501         /* If no mbuf passed, send an empty packet (ZLB) */
1502         if (m == NULL) {
1503                 /* Create a new mbuf for ZLB packet */
1504                 MGETHDR(m, M_NOWAIT, MT_DATA);
1505                 if (m == NULL) {
1506                         priv->stats.memoryFailures++;
1507                         return (ENOBUFS);
1508                 }
1509                 m->m_len = m->m_pkthdr.len = 12;
1510                 m->m_pkthdr.rcvif = NULL;
1511                 priv->stats.xmitZLBs++;
1512         } else {
1513                 /* Strip off session ID */
1514                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1515                         priv->stats.memoryFailures++;
1516                         return (ENOBUFS);
1517                 }
1518                 session_id = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
1519
1520                 /* Make room for L2TP header */
1521                 M_PREPEND(m, 10, M_NOWAIT);     /* - 2 + 12 = 10 */
1522                 if (m == NULL) {
1523                         priv->stats.memoryFailures++;
1524                         return (ENOBUFS);
1525                 }
1526
1527                 /*
1528                  * The below requires 12 contiguous bytes for the L2TP header
1529                  * to be written into.
1530                  */
1531                 m = m_pullup(m, 12);
1532                 if (m == NULL) {
1533                         priv->stats.memoryFailures++;
1534                         return (ENOBUFS);
1535                 }
1536         }
1537
1538         /* Fill in L2TP header */
1539         p = mtod(m, u_int8_t *);
1540         p[0] = L2TP_CTRL_HDR >> 8;
1541         p[1] = L2TP_CTRL_HDR & 0xff;
1542         p[2] = m->m_pkthdr.len >> 8;
1543         p[3] = m->m_pkthdr.len & 0xff;
1544         p[4] = priv->conf.peer_id >> 8;
1545         p[5] = priv->conf.peer_id & 0xff;
1546         p[6] = session_id >> 8;
1547         p[7] = session_id & 0xff;
1548         p[8] = ns >> 8;
1549         p[9] = ns & 0xff;
1550         p[10] = nr >> 8;
1551         p[11] = nr & 0xff;
1552
1553         /* Update sequence number info and stats */
1554         priv->stats.xmitPackets++;
1555         priv->stats.xmitOctets += m->m_pkthdr.len;
1556
1557         /* Send packet */
1558         NG_SEND_DATA_ONLY(error, priv->lower, m);
1559         return (error);
1560 }
1561
1562 #ifdef INVARIANTS
1563 /*
1564  * Sanity check sequence number state.
1565  */
1566 static void
1567 ng_l2tp_seq_check(struct l2tp_seq *seq)
1568 {
1569         int self_unack, peer_unack;
1570         int i;
1571
1572 #define CHECK(p)        KASSERT((p), ("%s: not: %s", __func__, #p))
1573
1574         SEQ_LOCK_ASSERT(seq);
1575
1576         self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1577         peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1578         CHECK(seq->wmax <= L2TP_MAX_XWIN);
1579         CHECK(seq->cwnd >= 1);
1580         CHECK(seq->cwnd <= seq->wmax);
1581         CHECK(seq->ssth >= 1);
1582         CHECK(seq->ssth <= seq->wmax);
1583         if (seq->cwnd < seq->ssth)
1584                 CHECK(seq->acks == 0);
1585         else
1586                 CHECK(seq->acks <= seq->cwnd);
1587         CHECK(self_unack >= 0);
1588         CHECK(peer_unack >= 0);
1589         CHECK(peer_unack <= seq->wmax);
1590         CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1591         CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1592         for (i = 0; i < peer_unack; i++)
1593                 CHECK(seq->xwin[i] != NULL);
1594         for ( ; i < seq->cwnd; i++)         /* verify peer's recv window full */
1595                 CHECK(seq->xwin[i] == NULL);
1596
1597 #undef CHECK
1598 }
1599 #endif  /* INVARIANTS */