ng_bpf.c

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    1 
    2 /*
    3  * ng_bpf.c
    4  *
    5  * Copyright (c) 1999 Whistle Communications, Inc.
    6  * All rights reserved.
    7  * 
    8  * Subject to the following obligations and disclaimer of warranty, use and
    9  * redistribution of this software, in source or object code forms, with or
   10  * without modifications are expressly permitted by Whistle Communications;
   11  * provided, however, that:
   12  * 1. Any and all reproductions of the source or object code must include the
   13  *    copyright notice above and the following disclaimer of warranties; and
   14  * 2. No rights are granted, in any manner or form, to use Whistle
   15  *    Communications, Inc. trademarks, including the mark "WHISTLE
   16  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   17  *    such appears in the above copyright notice or in the software.
   18  * 
   19  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   20  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   21  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   22  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   23  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   24  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANBPF, OR MAKE ANY
   25  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   26  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   27  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   28  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   29  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   30  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   31  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
   32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   34  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   35  * OF SUCH DAMAGE.
   36  *
   37  * Author: Archie Cobbs <archie@freebsd.org>
   38  *
   39  * $FreeBSD$
   40  * $Whistle: ng_bpf.c,v 1.3 1999/12/03 20:30:23 archie Exp $
   41  */
   42 
   43 /*
   44  * BPF NETGRAPH NODE TYPE
   45  *
   46  * This node type accepts any number of hook connections.  With each hook
   47  * is associated a bpf(4) filter program, and two hook names (each possibly
   48  * the empty string).  Incoming packets are compared against the filter;
   49  * matching packets are delivered out the first named hook (or dropped if
   50  * the empty string), and non-matching packets are delivered out the second
   51  * named hook (or dropped if the empty string).
   52  *
   53  * Each hook also keeps statistics about how many packets have matched, etc.
   54  */
   55 
   56 #include <sys/param.h>
   57 #include <sys/systm.h>
   58 #include <sys/errno.h>
   59 #include <sys/kernel.h>
   60 #include <sys/malloc.h>
   61 #include <sys/mbuf.h>
   62 
   63 #include <net/bpf.h>
   64 
   65 #include <netgraph/ng_message.h>
   66 #include <netgraph/netgraph.h>
   67 #include <netgraph/ng_parse.h>
   68 #include <netgraph/ng_bpf.h>
   69 
   70 #define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
   71 
   72 #define ERROUT(x)       do { error = (x); goto done; } while (0)
   73 
   74 /* Per hook private info */
   75 struct ng_bpf_hookinfo {
   76         node_p                  node;
   77         hook_p                  hook;
   78         struct ng_bpf_hookprog  *prog;
   79         struct ng_bpf_hookstat  stats;
   80 };
   81 typedef struct ng_bpf_hookinfo *hinfo_p;
   82 
   83 /* Netgraph methods */
   84 static ng_constructor_t ng_bpf_constructor;
   85 static ng_rcvmsg_t      ng_bpf_rcvmsg;
   86 static ng_shutdown_t    ng_bpf_rmnode;
   87 static ng_newhook_t     ng_bpf_newhook;
   88 static ng_rcvdata_t     ng_bpf_rcvdata;
   89 static ng_disconnect_t  ng_bpf_disconnect;
   90 
   91 /* Internal helper functions */
   92 static int      ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
   93 
   94 /* Parse type for one struct bfp_insn */
   95 static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
   96         { "code",       &ng_parse_hint16_type   },
   97         { "jt",         &ng_parse_uint8_type    },
   98         { "jf",         &ng_parse_uint8_type    },
   99         { "k",          &ng_parse_uint32_type   },
  100         { NULL }
  101 };
  102 static const struct ng_parse_type ng_bpf_insn_type = {
  103         &ng_parse_struct_type,
  104         &ng_bpf_insn_type_fields
  105 };
  106 
  107 /* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
  108 static int
  109 ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
  110         const u_char *start, const u_char *buf)
  111 {
  112         const struct ng_bpf_hookprog *hp;
  113 
  114         hp = (const struct ng_bpf_hookprog *)
  115             (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
  116         return hp->bpf_prog_len;
  117 }
  118 
  119 static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
  120         &ng_bpf_insn_type,
  121         &ng_bpf_hookprogary_getLength,
  122         NULL
  123 };
  124 static const struct ng_parse_type ng_bpf_hookprogary_type = {
  125         &ng_parse_array_type,
  126         &ng_bpf_hookprogary_info
  127 };
  128 
  129 /* Parse type for struct ng_bpf_hookprog */
  130 static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
  131         = NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
  132 static const struct ng_parse_type ng_bpf_hookprog_type = {
  133         &ng_parse_struct_type,
  134         &ng_bpf_hookprog_type_fields
  135 };
  136 
  137 /* Parse type for struct ng_bpf_hookstat */
  138 static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
  139         = NG_BPF_HOOKSTAT_TYPE_INFO;
  140 static const struct ng_parse_type ng_bpf_hookstat_type = {
  141         &ng_parse_struct_type,
  142         &ng_bpf_hookstat_type_fields
  143 };
  144 
  145 /* List of commands and how to convert arguments to/from ASCII */
  146 static const struct ng_cmdlist ng_bpf_cmdlist[] = {
  147         {
  148           NGM_BPF_COOKIE,
  149           NGM_BPF_SET_PROGRAM,
  150           "setprogram",
  151           &ng_bpf_hookprog_type,
  152           NULL
  153         },
  154         {
  155           NGM_BPF_COOKIE,
  156           NGM_BPF_GET_PROGRAM,
  157           "getprogram",
  158           &ng_parse_hookbuf_type,
  159           &ng_bpf_hookprog_type
  160         },
  161         {
  162           NGM_BPF_COOKIE,
  163           NGM_BPF_GET_STATS,
  164           "getstats",
  165           &ng_parse_hookbuf_type,
  166           &ng_bpf_hookstat_type
  167         },
  168         {
  169           NGM_BPF_COOKIE,
  170           NGM_BPF_CLR_STATS,
  171           "clrstats",
  172           &ng_parse_hookbuf_type,
  173           NULL
  174         },
  175         {
  176           NGM_BPF_COOKIE,
  177           NGM_BPF_GETCLR_STATS,
  178           "getclrstats",
  179           &ng_parse_hookbuf_type,
  180           &ng_bpf_hookstat_type
  181         },
  182         { 0 }
  183 };
  184 
  185 /* Netgraph type descriptor */
  186 static struct ng_type typestruct = {
  187         NG_VERSION,
  188         NG_BPF_NODE_TYPE,
  189         NULL,
  190         ng_bpf_constructor,
  191         ng_bpf_rcvmsg,
  192         ng_bpf_rmnode,
  193         ng_bpf_newhook,
  194         NULL,
  195         NULL,
  196         ng_bpf_rcvdata,
  197         ng_bpf_rcvdata,
  198         ng_bpf_disconnect,
  199         ng_bpf_cmdlist
  200 };
  201 NETGRAPH_INIT(bpf, &typestruct);
  202 
  203 /* Default BPF program for a hook that matches nothing */
  204 static const struct ng_bpf_hookprog ng_bpf_default_prog = {
  205         { '\0' },               /* to be filled in at hook creation time */
  206         { '\0' },
  207         { '\0' },
  208         1,
  209         { BPF_STMT(BPF_RET+BPF_K, 0) }
  210 };
  211 
  212 /*
  213  * Node constructor
  214  *
  215  * We don't keep any per-node private data
  216  */
  217 static int
  218 ng_bpf_constructor(node_p *nodep)
  219 {
  220         int error = 0;
  221 
  222         if ((error = ng_make_node_common(&typestruct, nodep)))
  223                 return (error);
  224         (*nodep)->private = NULL;
  225         return (0);
  226 }
  227 
  228 /*
  229  * Add a hook
  230  */
  231 static int
  232 ng_bpf_newhook(node_p node, hook_p hook, const char *name)
  233 {
  234         hinfo_p hip;
  235         int error;
  236 
  237         /* Create hook private structure */
  238         MALLOC(hip, hinfo_p, sizeof(*hip), M_NETGRAPH, M_NOWAIT);
  239         if (hip == NULL)
  240                 return (ENOMEM);
  241         bzero(hip, sizeof(*hip));
  242         hip->hook = hook;
  243         hook->private = hip;
  244         hip->node = node;
  245 
  246         /* Attach the default BPF program */
  247         if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
  248                 FREE(hip, M_NETGRAPH);
  249                 hook->private = NULL;
  250                 return (error);
  251         }
  252 
  253         /* Set hook name */
  254         strncpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook) - 1);
  255         hip->prog->thisHook[sizeof(hip->prog->thisHook) - 1] = '\0';
  256         return (0);
  257 }
  258 
  259 /*
  260  * Receive a control message
  261  */
  262 static int
  263 ng_bpf_rcvmsg(node_p node, struct ng_mesg *msg, const char *retaddr,
  264            struct ng_mesg **rptr)
  265 {
  266         struct ng_mesg *resp = NULL;
  267         int error = 0;
  268 
  269         switch (msg->header.typecookie) {
  270         case NGM_BPF_COOKIE:
  271                 switch (msg->header.cmd) {
  272                 case NGM_BPF_SET_PROGRAM:
  273                     {
  274                         struct ng_bpf_hookprog *const
  275                             hp = (struct ng_bpf_hookprog *)msg->data;
  276                         hook_p hook;
  277 
  278                         /* Sanity check */
  279                         if (msg->header.arglen < sizeof(*hp)
  280                             || msg->header.arglen
  281                               != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
  282                                 ERROUT(EINVAL);
  283 
  284                         /* Find hook */
  285                         if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
  286                                 ERROUT(ENOENT);
  287 
  288                         /* Set new program */
  289                         if ((error = ng_bpf_setprog(hook, hp)) != 0)
  290                                 ERROUT(error);
  291                         break;
  292                     }
  293 
  294                 case NGM_BPF_GET_PROGRAM:
  295                     {
  296                         struct ng_bpf_hookprog *hp;
  297                         hook_p hook;
  298 
  299                         /* Sanity check */
  300                         if (msg->header.arglen == 0)
  301                                 ERROUT(EINVAL);
  302                         msg->data[msg->header.arglen - 1] = '\0';
  303 
  304                         /* Find hook */
  305                         if ((hook = ng_findhook(node, msg->data)) == NULL)
  306                                 ERROUT(ENOENT);
  307 
  308                         /* Build response */
  309                         hp = ((hinfo_p)hook->private)->prog;
  310                         NG_MKRESPONSE(resp, msg,
  311                             NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
  312                         if (resp == NULL)
  313                                 ERROUT(ENOMEM);
  314                         bcopy(hp, resp->data,
  315                            NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
  316                         break;
  317                     }
  318 
  319                 case NGM_BPF_GET_STATS:
  320                 case NGM_BPF_CLR_STATS:
  321                 case NGM_BPF_GETCLR_STATS:
  322                     {
  323                         struct ng_bpf_hookstat *stats;
  324                         hook_p hook;
  325 
  326                         /* Sanity check */
  327                         if (msg->header.arglen == 0)
  328                                 ERROUT(EINVAL);
  329                         msg->data[msg->header.arglen - 1] = '\0';
  330 
  331                         /* Find hook */
  332                         if ((hook = ng_findhook(node, msg->data)) == NULL)
  333                                 ERROUT(ENOENT);
  334                         stats = &((hinfo_p)hook->private)->stats;
  335 
  336                         /* Build response (if desired) */
  337                         if (msg->header.cmd != NGM_BPF_CLR_STATS) {
  338                                 NG_MKRESPONSE(resp,
  339                                     msg, sizeof(*stats), M_NOWAIT);
  340                                 if (resp == NULL)
  341                                         ERROUT(ENOMEM);
  342                                 bcopy(stats, resp->data, sizeof(*stats));
  343                         }
  344 
  345                         /* Clear stats (if desired) */
  346                         if (msg->header.cmd != NGM_BPF_GET_STATS)
  347                                 bzero(stats, sizeof(*stats));
  348                         break;
  349                     }
  350 
  351                 default:
  352                         error = EINVAL;
  353                         break;
  354                 }
  355                 break;
  356         default:
  357                 error = EINVAL;
  358                 break;
  359         }
  360         if (rptr)
  361                 *rptr = resp;
  362         else if (resp)
  363                 FREE(resp, M_NETGRAPH);
  364 
  365 done:
  366         FREE(msg, M_NETGRAPH);
  367         return (error);
  368 }
  369 
  370 /*
  371  * Receive data on a hook
  372  *
  373  * Apply the filter, and then drop or forward packet as appropriate.
  374  */
  375 static int
  376 ng_bpf_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
  377 {
  378         const hinfo_p hip = hook->private;
  379         int totlen = m->m_pkthdr.len;
  380         int needfree = 0, error = 0;
  381         u_char *data, buf[256];
  382         hinfo_p dhip;
  383         hook_p dest;
  384         u_int len;
  385 
  386         /* Update stats on incoming hook */
  387         hip->stats.recvFrames++;
  388         hip->stats.recvOctets += totlen;
  389 
  390         /* Need to put packet in contiguous memory for bpf */
  391         if (m->m_next != NULL) {
  392                 if (totlen > sizeof(buf)) {
  393                         MALLOC(data, u_char *, totlen, M_NETGRAPH, M_NOWAIT);
  394                         if (data == NULL) {
  395                                 NG_FREE_DATA(m, meta);
  396                                 return (ENOMEM);
  397                         }
  398                         needfree = 1;
  399                 } else
  400                         data = buf;
  401                 m_copydata(m, 0, totlen, (caddr_t)data);
  402         } else
  403                 data = mtod(m, u_char *);
  404 
  405         /* Run packet through filter */
  406         if (totlen == 0)
  407                 len = 0;        /* don't call bpf_filter() with totlen == 0! */
  408         else
  409                 len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
  410         if (needfree)
  411                 FREE(data, M_NETGRAPH);
  412 
  413         /* See if we got a match and find destination hook */
  414         if (len > 0) {
  415 
  416                 /* Update stats */
  417                 hip->stats.recvMatchFrames++;
  418                 hip->stats.recvMatchOctets += totlen;
  419 
  420                 /* Truncate packet length if required by the filter */
  421                 if (len < totlen) {
  422                         m_adj(m, -(totlen - len));
  423                         totlen -= len;
  424                 }
  425                 dest = ng_findhook(hip->node, hip->prog->ifMatch);
  426         } else
  427                 dest = ng_findhook(hip->node, hip->prog->ifNotMatch);
  428         if (dest == NULL) {
  429                 NG_FREE_DATA(m, meta);
  430                 return (0);
  431         }
  432 
  433         /* Deliver frame out destination hook */
  434         dhip = (hinfo_p)dest->private;
  435         dhip->stats.xmitOctets += totlen;
  436         dhip->stats.xmitFrames++;
  437         NG_SEND_DATA(error, dest, m, meta);
  438         return (error);
  439 }
  440 
  441 /*
  442  * Shutdown processing
  443  */
  444 static int
  445 ng_bpf_rmnode(node_p node)
  446 {
  447         node->flags |= NG_INVALID;
  448         ng_cutlinks(node);
  449         ng_unname(node);
  450         ng_unref(node);
  451         return (0);
  452 }
  453 
  454 /*
  455  * Hook disconnection
  456  */
  457 static int
  458 ng_bpf_disconnect(hook_p hook)
  459 {
  460         const hinfo_p hip = hook->private;
  461 
  462         KASSERT(hip != NULL, ("%s: null info", __FUNCTION__));
  463         FREE(hip->prog, M_NETGRAPH);
  464         bzero(hip, sizeof(*hip));
  465         FREE(hip, M_NETGRAPH);
  466         hook->private = NULL;                   /* for good measure */
  467         if (hook->node->numhooks == 0)
  468                 ng_rmnode(hook->node);
  469         return (0);
  470 }
  471 
  472 /************************************************************************
  473                         HELPER STUFF
  474  ************************************************************************/
  475 
  476 /*
  477  * Set the BPF program associated with a hook
  478  */
  479 static int
  480 ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
  481 {
  482         const hinfo_p hip = hook->private;
  483         struct ng_bpf_hookprog *hp;
  484         int size;
  485 
  486         /* Check program for validity */
  487         if (!bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
  488                 return (EINVAL);
  489 
  490         /* Make a copy of the program */
  491         size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
  492         MALLOC(hp, struct ng_bpf_hookprog *, size, M_NETGRAPH, M_NOWAIT);
  493         if (hp == NULL)
  494                 return (ENOMEM);
  495         bcopy(hp0, hp, size);
  496 
  497         /* Free previous program, if any, and assign new one */
  498         if (hip->prog != NULL)
  499                 FREE(hip->prog, M_NETGRAPH);
  500         hip->prog = hp;
  501         return (0);
  502 }
  503
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FreeBSD/Linux Kernel Cross Reference sys/netgraph/ng_bpf.c

FreeBSD/Linux Kernel Cross Reference
sys/netgraph/ng_bpf.c
