The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netgraph/ng_bpf.c

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    1 /*
    2  * ng_bpf.c
    3  */
    4 
    5 /*-
    6  * Copyright (c) 1999 Whistle Communications, Inc.
    7  * All rights reserved.
    8  * 
    9  * Subject to the following obligations and disclaimer of warranty, use and
   10  * redistribution of this software, in source or object code forms, with or
   11  * without modifications are expressly permitted by Whistle Communications;
   12  * provided, however, that:
   13  * 1. Any and all reproductions of the source or object code must include the
   14  *    copyright notice above and the following disclaimer of warranties; and
   15  * 2. No rights are granted, in any manner or form, to use Whistle
   16  *    Communications, Inc. trademarks, including the mark "WHISTLE
   17  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   18  *    such appears in the above copyright notice or in the software.
   19  * 
   20  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   21  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   22  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   23  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   25  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
   26  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   27  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   28  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   29  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   30  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   31  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   32  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
   33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   35  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   36  * OF SUCH DAMAGE.
   37  *
   38  * Author: Archie Cobbs <archie@freebsd.org>
   39  *
   40  * $FreeBSD: releng/11.1/sys/netgraph/ng_bpf.c 227293 2011-11-07 06:44:47Z ed $
   41  * $Whistle: ng_bpf.c,v 1.3 1999/12/03 20:30:23 archie Exp $
   42  */
   43 
   44 /*
   45  * BPF NETGRAPH NODE TYPE
   46  *
   47  * This node type accepts any number of hook connections.  With each hook
   48  * is associated a bpf(4) filter program, and two hook names (each possibly
   49  * the empty string).  Incoming packets are compared against the filter;
   50  * matching packets are delivered out the first named hook (or dropped if
   51  * the empty string), and non-matching packets are delivered out the second
   52  * named hook (or dropped if the empty string).
   53  *
   54  * Each hook also keeps statistics about how many packets have matched, etc.
   55  */
   56 
   57 #include "opt_bpf.h"
   58 
   59 #include <sys/param.h>
   60 #include <sys/systm.h>
   61 #include <sys/errno.h>
   62 #include <sys/kernel.h>
   63 #include <sys/malloc.h>
   64 #include <sys/mbuf.h>
   65 
   66 #include <net/bpf.h>
   67 #ifdef BPF_JITTER
   68 #include <net/bpf_jitter.h>
   69 #endif
   70 
   71 #include <netgraph/ng_message.h>
   72 #include <netgraph/netgraph.h>
   73 #include <netgraph/ng_parse.h>
   74 #include <netgraph/ng_bpf.h>
   75 
   76 #ifdef NG_SEPARATE_MALLOC
   77 static MALLOC_DEFINE(M_NETGRAPH_BPF, "netgraph_bpf", "netgraph bpf node");
   78 #else
   79 #define M_NETGRAPH_BPF M_NETGRAPH
   80 #endif
   81 
   82 #define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
   83 
   84 #define ERROUT(x)       do { error = (x); goto done; } while (0)
   85 
   86 /* Per hook private info */
   87 struct ng_bpf_hookinfo {
   88         hook_p                  hook;
   89         hook_p                  match;
   90         hook_p                  nomatch;
   91         struct ng_bpf_hookprog  *prog;
   92 #ifdef BPF_JITTER
   93         bpf_jit_filter          *jit_prog;
   94 #endif
   95         struct ng_bpf_hookstat  stats;
   96 };
   97 typedef struct ng_bpf_hookinfo *hinfo_p;
   98 
   99 /* Netgraph methods */
  100 static ng_constructor_t ng_bpf_constructor;
  101 static ng_rcvmsg_t      ng_bpf_rcvmsg;
  102 static ng_shutdown_t    ng_bpf_shutdown;
  103 static ng_newhook_t     ng_bpf_newhook;
  104 static ng_rcvdata_t     ng_bpf_rcvdata;
  105 static ng_disconnect_t  ng_bpf_disconnect;
  106 
  107 /* Maximum bpf program instructions */
  108 extern int      bpf_maxinsns;
  109 
  110 /* Internal helper functions */
  111 static int      ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
  112 
  113 /* Parse type for one struct bfp_insn */
  114 static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
  115         { "code",       &ng_parse_hint16_type   },
  116         { "jt",         &ng_parse_uint8_type    },
  117         { "jf",         &ng_parse_uint8_type    },
  118         { "k",          &ng_parse_uint32_type   },
  119         { NULL }
  120 };
  121 static const struct ng_parse_type ng_bpf_insn_type = {
  122         &ng_parse_struct_type,
  123         &ng_bpf_insn_type_fields
  124 };
  125 
  126 /* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
  127 static int
  128 ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
  129         const u_char *start, const u_char *buf)
  130 {
  131         const struct ng_bpf_hookprog *hp;
  132 
  133         hp = (const struct ng_bpf_hookprog *)
  134             (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
  135         return hp->bpf_prog_len;
  136 }
  137 
  138 static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
  139         &ng_bpf_insn_type,
  140         &ng_bpf_hookprogary_getLength,
  141         NULL
  142 };
  143 static const struct ng_parse_type ng_bpf_hookprogary_type = {
  144         &ng_parse_array_type,
  145         &ng_bpf_hookprogary_info
  146 };
  147 
  148 /* Parse type for struct ng_bpf_hookprog */
  149 static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
  150         = NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
  151 static const struct ng_parse_type ng_bpf_hookprog_type = {
  152         &ng_parse_struct_type,
  153         &ng_bpf_hookprog_type_fields
  154 };
  155 
  156 /* Parse type for struct ng_bpf_hookstat */
  157 static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
  158         = NG_BPF_HOOKSTAT_TYPE_INFO;
  159 static const struct ng_parse_type ng_bpf_hookstat_type = {
  160         &ng_parse_struct_type,
  161         &ng_bpf_hookstat_type_fields
  162 };
  163 
  164 /* List of commands and how to convert arguments to/from ASCII */
  165 static const struct ng_cmdlist ng_bpf_cmdlist[] = {
  166         {
  167           NGM_BPF_COOKIE,
  168           NGM_BPF_SET_PROGRAM,
  169           "setprogram",
  170           &ng_bpf_hookprog_type,
  171           NULL
  172         },
  173         {
  174           NGM_BPF_COOKIE,
  175           NGM_BPF_GET_PROGRAM,
  176           "getprogram",
  177           &ng_parse_hookbuf_type,
  178           &ng_bpf_hookprog_type
  179         },
  180         {
  181           NGM_BPF_COOKIE,
  182           NGM_BPF_GET_STATS,
  183           "getstats",
  184           &ng_parse_hookbuf_type,
  185           &ng_bpf_hookstat_type
  186         },
  187         {
  188           NGM_BPF_COOKIE,
  189           NGM_BPF_CLR_STATS,
  190           "clrstats",
  191           &ng_parse_hookbuf_type,
  192           NULL
  193         },
  194         {
  195           NGM_BPF_COOKIE,
  196           NGM_BPF_GETCLR_STATS,
  197           "getclrstats",
  198           &ng_parse_hookbuf_type,
  199           &ng_bpf_hookstat_type
  200         },
  201         { 0 }
  202 };
  203 
  204 /* Netgraph type descriptor */
  205 static struct ng_type typestruct = {
  206         .version =      NG_ABI_VERSION,
  207         .name =         NG_BPF_NODE_TYPE,
  208         .constructor =  ng_bpf_constructor,
  209         .rcvmsg =       ng_bpf_rcvmsg,
  210         .shutdown =     ng_bpf_shutdown,
  211         .newhook =      ng_bpf_newhook,
  212         .rcvdata =      ng_bpf_rcvdata,
  213         .disconnect =   ng_bpf_disconnect,
  214         .cmdlist =      ng_bpf_cmdlist,
  215 };
  216 NETGRAPH_INIT(bpf, &typestruct);
  217 
  218 /* Default BPF program for a hook that matches nothing */
  219 static const struct ng_bpf_hookprog ng_bpf_default_prog = {
  220         { '\0' },               /* to be filled in at hook creation time */
  221         { '\0' },
  222         { '\0' },
  223         1,
  224         { BPF_STMT(BPF_RET+BPF_K, 0) }
  225 };
  226 
  227 /*
  228  * Node constructor
  229  *
  230  * We don't keep any per-node private data
  231  * We go via the hooks.
  232  */
  233 static int
  234 ng_bpf_constructor(node_p node)
  235 {
  236         NG_NODE_SET_PRIVATE(node, NULL);
  237         return (0);
  238 }
  239 
  240 /*
  241  * Callback functions to be used by NG_NODE_FOREACH_HOOK() macro.
  242  */
  243 static int
  244 ng_bpf_addrefs(hook_p hook, void* arg)
  245 {
  246         hinfo_p hip = NG_HOOK_PRIVATE(hook);
  247         hook_p h = (hook_p)arg;
  248 
  249         if (strcmp(hip->prog->ifMatch, NG_HOOK_NAME(h)) == 0)
  250             hip->match = h;
  251         if (strcmp(hip->prog->ifNotMatch, NG_HOOK_NAME(h)) == 0)
  252             hip->nomatch = h;
  253         return (1);
  254 }
  255 
  256 static int
  257 ng_bpf_remrefs(hook_p hook, void* arg)
  258 {
  259         hinfo_p hip = NG_HOOK_PRIVATE(hook);
  260         hook_p h = (hook_p)arg;
  261 
  262         if (hip->match == h)
  263             hip->match = NULL;
  264         if (hip->nomatch == h)
  265             hip->nomatch = NULL;
  266         return (1);
  267 }
  268 
  269 /*
  270  * Add a hook
  271  */
  272 static int
  273 ng_bpf_newhook(node_p node, hook_p hook, const char *name)
  274 {
  275         hinfo_p hip;
  276         hook_p tmp;
  277         int error;
  278 
  279         /* Create hook private structure */
  280         hip = malloc(sizeof(*hip), M_NETGRAPH_BPF, M_NOWAIT | M_ZERO);
  281         if (hip == NULL)
  282                 return (ENOMEM);
  283         hip->hook = hook;
  284         NG_HOOK_SET_PRIVATE(hook, hip);
  285 
  286         /* Add our reference into other hooks data. */
  287         NG_NODE_FOREACH_HOOK(node, ng_bpf_addrefs, hook, tmp);
  288 
  289         /* Attach the default BPF program */
  290         if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
  291                 free(hip, M_NETGRAPH_BPF);
  292                 NG_HOOK_SET_PRIVATE(hook, NULL);
  293                 return (error);
  294         }
  295 
  296         /* Set hook name */
  297         strlcpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook));
  298         return (0);
  299 }
  300 
  301 /*
  302  * Receive a control message
  303  */
  304 static int
  305 ng_bpf_rcvmsg(node_p node, item_p item, hook_p lasthook)
  306 {
  307         struct ng_mesg *msg;
  308         struct ng_mesg *resp = NULL;
  309         int error = 0;
  310 
  311         NGI_GET_MSG(item, msg);
  312         switch (msg->header.typecookie) {
  313         case NGM_BPF_COOKIE:
  314                 switch (msg->header.cmd) {
  315                 case NGM_BPF_SET_PROGRAM:
  316                     {
  317                         struct ng_bpf_hookprog *const
  318                             hp = (struct ng_bpf_hookprog *)msg->data;
  319                         hook_p hook;
  320 
  321                         /* Sanity check */
  322                         if (msg->header.arglen < sizeof(*hp)
  323                             || msg->header.arglen
  324                               != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
  325                                 ERROUT(EINVAL);
  326 
  327                         /* Find hook */
  328                         if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
  329                                 ERROUT(ENOENT);
  330 
  331                         /* Set new program */
  332                         if ((error = ng_bpf_setprog(hook, hp)) != 0)
  333                                 ERROUT(error);
  334                         break;
  335                     }
  336 
  337                 case NGM_BPF_GET_PROGRAM:
  338                     {
  339                         struct ng_bpf_hookprog *hp;
  340                         hook_p hook;
  341 
  342                         /* Sanity check */
  343                         if (msg->header.arglen == 0)
  344                                 ERROUT(EINVAL);
  345                         msg->data[msg->header.arglen - 1] = '\0';
  346 
  347                         /* Find hook */
  348                         if ((hook = ng_findhook(node, msg->data)) == NULL)
  349                                 ERROUT(ENOENT);
  350 
  351                         /* Build response */
  352                         hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->prog;
  353                         NG_MKRESPONSE(resp, msg,
  354                             NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
  355                         if (resp == NULL)
  356                                 ERROUT(ENOMEM);
  357                         bcopy(hp, resp->data,
  358                            NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
  359                         break;
  360                     }
  361 
  362                 case NGM_BPF_GET_STATS:
  363                 case NGM_BPF_CLR_STATS:
  364                 case NGM_BPF_GETCLR_STATS:
  365                     {
  366                         struct ng_bpf_hookstat *stats;
  367                         hook_p hook;
  368 
  369                         /* Sanity check */
  370                         if (msg->header.arglen == 0)
  371                                 ERROUT(EINVAL);
  372                         msg->data[msg->header.arglen - 1] = '\0';
  373 
  374                         /* Find hook */
  375                         if ((hook = ng_findhook(node, msg->data)) == NULL)
  376                                 ERROUT(ENOENT);
  377                         stats = &((hinfo_p)NG_HOOK_PRIVATE(hook))->stats;
  378 
  379                         /* Build response (if desired) */
  380                         if (msg->header.cmd != NGM_BPF_CLR_STATS) {
  381                                 NG_MKRESPONSE(resp,
  382                                     msg, sizeof(*stats), M_NOWAIT);
  383                                 if (resp == NULL)
  384                                         ERROUT(ENOMEM);
  385                                 bcopy(stats, resp->data, sizeof(*stats));
  386                         }
  387 
  388                         /* Clear stats (if desired) */
  389                         if (msg->header.cmd != NGM_BPF_GET_STATS)
  390                                 bzero(stats, sizeof(*stats));
  391                         break;
  392                     }
  393 
  394                 default:
  395                         error = EINVAL;
  396                         break;
  397                 }
  398                 break;
  399         default:
  400                 error = EINVAL;
  401                 break;
  402         }
  403 done:
  404         NG_RESPOND_MSG(error, node, item, resp);
  405         NG_FREE_MSG(msg);
  406         return (error);
  407 }
  408 
  409 /*
  410  * Receive data on a hook
  411  *
  412  * Apply the filter, and then drop or forward packet as appropriate.
  413  */
  414 static int
  415 ng_bpf_rcvdata(hook_p hook, item_p item)
  416 {
  417         const hinfo_p hip = NG_HOOK_PRIVATE(hook);
  418         int totlen;
  419         int needfree = 0, error = 0, usejit = 0;
  420         u_char *data = NULL;
  421         hinfo_p dhip;
  422         hook_p dest;
  423         u_int len;
  424         struct mbuf *m;
  425 
  426         m = NGI_M(item);        /* 'item' still owns it.. we are peeking */ 
  427         totlen = m->m_pkthdr.len;
  428         /* Update stats on incoming hook. XXX Can we do 64 bits atomically? */
  429         /* atomic_add_int64(&hip->stats.recvFrames, 1); */
  430         /* atomic_add_int64(&hip->stats.recvOctets, totlen); */
  431         hip->stats.recvFrames++; 
  432         hip->stats.recvOctets += totlen;
  433 
  434         /* Don't call bpf_filter() with totlen == 0! */
  435         if (totlen == 0) {
  436                 len = 0;
  437                 goto ready;
  438         }
  439 
  440 #ifdef BPF_JITTER
  441         if (bpf_jitter_enable != 0 && hip->jit_prog != NULL)
  442                 usejit = 1;
  443 #endif
  444 
  445         /* Need to put packet in contiguous memory for bpf */
  446         if (m->m_next != NULL && totlen > MHLEN) {
  447                 if (usejit) {
  448                         data = malloc(totlen, M_NETGRAPH_BPF, M_NOWAIT);
  449                         if (data == NULL) {
  450                                 NG_FREE_ITEM(item);
  451                                 return (ENOMEM);
  452                         }
  453                         needfree = 1;
  454                         m_copydata(m, 0, totlen, (caddr_t)data);
  455                 }
  456         } else {
  457                 if (m->m_next != NULL) {
  458                         NGI_M(item) = m = m_pullup(m, totlen);
  459                         if (m == NULL) {
  460                                 NG_FREE_ITEM(item);
  461                                 return (ENOBUFS);
  462                         }
  463                 }
  464                 data = mtod(m, u_char *);
  465         }
  466 
  467         /* Run packet through filter */
  468 #ifdef BPF_JITTER
  469         if (usejit)
  470                 len = (*(hip->jit_prog->func))(data, totlen, totlen);
  471         else
  472 #endif
  473         if (data)
  474                 len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
  475         else
  476                 len = bpf_filter(hip->prog->bpf_prog, (u_char *)m, totlen, 0);
  477         if (needfree)
  478                 free(data, M_NETGRAPH_BPF);
  479 ready:
  480         /* See if we got a match and find destination hook */
  481         if (len > 0) {
  482 
  483                 /* Update stats */
  484                 /* XXX atomically? */
  485                 hip->stats.recvMatchFrames++;
  486                 hip->stats.recvMatchOctets += totlen;
  487 
  488                 /* Truncate packet length if required by the filter */
  489                 /* Assume this never changes m */
  490                 if (len < totlen) {
  491                         m_adj(m, -(totlen - len));
  492                         totlen = len;
  493                 }
  494                 dest = hip->match;
  495         } else
  496                 dest = hip->nomatch;
  497         if (dest == NULL) {
  498                 NG_FREE_ITEM(item);
  499                 return (0);
  500         }
  501 
  502         /* Deliver frame out destination hook */
  503         dhip = NG_HOOK_PRIVATE(dest);
  504         dhip->stats.xmitOctets += totlen;
  505         dhip->stats.xmitFrames++;
  506         NG_FWD_ITEM_HOOK(error, item, dest);
  507         return (error);
  508 }
  509 
  510 /*
  511  * Shutdown processing
  512  */
  513 static int
  514 ng_bpf_shutdown(node_p node)
  515 {
  516         NG_NODE_UNREF(node);
  517         return (0);
  518 }
  519 
  520 /*
  521  * Hook disconnection
  522  */
  523 static int
  524 ng_bpf_disconnect(hook_p hook)
  525 {
  526         const node_p node = NG_HOOK_NODE(hook);
  527         const hinfo_p hip = NG_HOOK_PRIVATE(hook);
  528         hook_p tmp;
  529 
  530         KASSERT(hip != NULL, ("%s: null info", __func__));
  531 
  532         /* Remove our reference from other hooks data. */
  533         NG_NODE_FOREACH_HOOK(node, ng_bpf_remrefs, hook, tmp);
  534 
  535         free(hip->prog, M_NETGRAPH_BPF);
  536 #ifdef BPF_JITTER
  537         if (hip->jit_prog != NULL)
  538                 bpf_destroy_jit_filter(hip->jit_prog);
  539 #endif
  540         free(hip, M_NETGRAPH_BPF);
  541         if ((NG_NODE_NUMHOOKS(node) == 0) &&
  542             (NG_NODE_IS_VALID(node))) {
  543                 ng_rmnode_self(node);
  544         }
  545         return (0);
  546 }
  547 
  548 /************************************************************************
  549                         HELPER STUFF
  550  ************************************************************************/
  551 
  552 /*
  553  * Set the BPF program associated with a hook
  554  */
  555 static int
  556 ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
  557 {
  558         const hinfo_p hip = NG_HOOK_PRIVATE(hook);
  559         struct ng_bpf_hookprog *hp;
  560 #ifdef BPF_JITTER
  561         bpf_jit_filter *jit_prog;
  562 #endif
  563         int size;
  564 
  565         /* Check program for validity */
  566         if (hp0->bpf_prog_len > bpf_maxinsns ||
  567             !bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
  568                 return (EINVAL);
  569 
  570         /* Make a copy of the program */
  571         size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
  572         hp = malloc(size, M_NETGRAPH_BPF, M_NOWAIT);
  573         if (hp == NULL)
  574                 return (ENOMEM);
  575         bcopy(hp0, hp, size);
  576 #ifdef BPF_JITTER
  577         jit_prog = bpf_jitter(hp->bpf_prog, hp->bpf_prog_len);
  578 #endif
  579 
  580         /* Free previous program, if any, and assign new one */
  581         if (hip->prog != NULL)
  582                 free(hip->prog, M_NETGRAPH_BPF);
  583         hip->prog = hp;
  584 #ifdef BPF_JITTER
  585         if (hip->jit_prog != NULL)
  586                 bpf_destroy_jit_filter(hip->jit_prog);
  587         hip->jit_prog = jit_prog;
  588 #endif
  589 
  590         /* Prepare direct references on target hooks. */
  591         hip->match = ng_findhook(NG_HOOK_NODE(hook), hip->prog->ifMatch);
  592         hip->nomatch = ng_findhook(NG_HOOK_NODE(hook), hip->prog->ifNotMatch);
  593         return (0);
  594 }

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