mDNSMacOSX/P2PPacketFilter.c

   1 /*
   2  *
   3  * Copyright (c) 2011 Apple Inc. All rights reserved.
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  */
  17
  18 #include <net/if.h>
  19 #include <System/net/pfvar.h>
  20 #include <string.h>
  21 #include <fcntl.h>
  22 #include <errno.h>
  23 #include <sys/ioctl.h>
  24 #include <unistd.h>
  25 #include <AssertMacros.h>
  26 #include "P2PPacketFilter.h"
  27
  28 #define AIRDROP_ANCHOR_PATH     "com.apple/200.AirDrop"
  29 #define MDNS_ANCHOR_NAME        "Bonjour"
  30 #define MDNS_ANCHOR_PATH        AIRDROP_ANCHOR_PATH "/" MDNS_ANCHOR_NAME
  31
  32 #define PF_DEV_PATH "/dev/pf"
  33 #define BONJOUR_PORT 5353
  34
  35 static int openPFDevice( int * outFD )
  36 {
  37     int err;
  38     int fd = open( PF_DEV_PATH, O_RDWR );
  39
  40     if( fd >= 0 )
  41     {
  42         err = 0;
  43         *outFD = fd;
  44     }
  45     else
  46     {
  47         err = errno;
  48     }
  49
  50     return err;
  51 }
  52
  53 static int getTicket( int devFD, u_int32_t * outTicket, char * anchorPath )
  54 {
  55     struct pfioc_trans_e trans_e;
  56
  57     trans_e.rs_num = PF_RULESET_FILTER;
  58     strlcpy( trans_e.anchor, anchorPath, sizeof( trans_e.anchor ) );
  59
  60     struct pfioc_trans trans;
  61
  62     trans.size = 1;
  63     trans.esize = sizeof( trans_e );
  64     trans.array = &trans_e;
  65
  66     int result, ioctlError;
  67
  68     ioctlError = ioctl( devFD, DIOCXBEGIN, &trans );
  69     if( ioctlError )
  70     {
  71         result = errno;
  72     }
  73     else
  74     {
  75         result = 0;
  76         *outTicket = trans_e.ticket;
  77     }
  78
  79     return result;
  80 }
  81
  82 static int commitChange( int devFD, u_int32_t ticket, char * anchorPath )
  83 {
  84     struct pfioc_trans_e trans_e;
  85
  86     trans_e.rs_num = PF_RULESET_FILTER;
  87     strlcpy( trans_e.anchor, anchorPath, sizeof( trans_e.anchor ) );
  88     trans_e.ticket = ticket;
  89
  90     struct pfioc_trans trans;
  91
  92     trans.size = 1;
  93     trans.esize = sizeof( trans_e );
  94     trans.array = &trans_e;
  95
  96     int result, ioctlError;
  97
  98     ioctlError = ioctl( devFD, DIOCXCOMMIT, &trans );
  99     if( ioctlError )
 100         result = errno;
 101     else
 102         result = 0;
 103
 104     return result;
 105 }
 106
 107 static int getPoolTicket( int devFD, u_int32_t * outPoolTicket )
 108 {
 109     struct pfioc_pooladdr pp;
 110
 111     int result, ioctlError;
 112
 113     ioctlError = ioctl( devFD, DIOCBEGINADDRS, &pp );
 114     if( ioctlError )
 115     {
 116         result = errno;
 117     }
 118     else
 119     {
 120         result = 0;
 121         *outPoolTicket = pp.ticket;
 122     }
 123
 124     return result;
 125 }
 126
 127 static int addRule( int devFD, struct pfioc_rule * pr )
 128 {
 129     int result, ioctlResult;
 130
 131     ioctlResult = ioctl( devFD, DIOCADDRULE, pr );
 132     if( ioctlResult )
 133         result = errno;
 134     else
 135         result = 0;
 136
 137     return result;
 138 }
 139
 140 static void initRuleHeader( struct pfioc_rule * pr,
 141                              u_int32_t ticket,
 142                              u_int32_t poolTicket,
 143                                                          char * anchorPath )
 144 {
 145     pr->action = PF_CHANGE_NONE;
 146     pr->ticket = ticket;
 147     pr->pool_ticket = poolTicket;
 148     strlcpy( pr->anchor, anchorPath, sizeof( pr->anchor ) );
 149 }
 150
 151 // allow inbound traffice on the Bonjour port (5353)
 152 static void initBonjourRule( struct pfioc_rule * pr,
 153                               const char * interfaceName,
 154                               u_int32_t ticket,
 155                               u_int32_t poolTicket,
 156                                                           char * anchorPath )
 157 {
 158     memset( pr, 0, sizeof( *pr ) );
 159
 160     // Header
 161     initRuleHeader( pr, ticket, poolTicket, anchorPath );
 162
 163     // Rule
 164     pr->rule.dst.xport.range.port[0] = htons( BONJOUR_PORT );
 165     pr->rule.dst.xport.range.op = PF_OP_EQ;
 166
 167     strlcpy( pr->rule.ifname, interfaceName, sizeof( pr->rule.ifname ) );
 168
 169     pr->rule.action = PF_PASS;
 170     pr->rule.direction = PF_IN;
 171     pr->rule.keep_state = 1;
 172     pr->rule.af = AF_INET6;
 173     pr->rule.proto = IPPROTO_UDP;
 174     pr->rule.extfilter = PF_EXTFILTER_APD;
 175 }
 176
 177 // allow outbound TCP connections and return traffic for those connections
 178 static void initOutboundTCPRule( struct pfioc_rule * pr,
 179                              const char * interfaceName,
 180                              u_int32_t ticket,
 181                              u_int32_t poolTicket,
 182                                                          char * anchorPath )
 183 {
 184     memset( pr, 0, sizeof( *pr ) );
 185
 186     // Header
 187     initRuleHeader( pr, ticket, poolTicket, anchorPath );
 188
 189     // Rule
 190     strlcpy( pr->rule.ifname, interfaceName, sizeof( pr->rule.ifname ) );
 191
 192     pr->rule.action = PF_PASS;
 193     pr->rule.direction = PF_OUT;
 194     pr->rule.keep_state = 1;
 195     pr->rule.proto = IPPROTO_TCP;
 196 }
 197
 198 // allow inbound traffic on the specified port and protocol
 199 static void initPortRule( struct pfioc_rule * pr,
 200                               const char * interfaceName,
 201                               u_int32_t ticket,
 202                               u_int32_t poolTicket,
 203                                                           char * anchorPath,
 204                                                           u_int16_t port,
 205                                                           u_int16_t protocol )
 206 {
 207     memset( pr, 0, sizeof( *pr ) );
 208
 209     // Header
 210     initRuleHeader( pr, ticket, poolTicket, anchorPath );
 211
 212     // Rule
 213         // mDNSResponder passes the port in Network Byte Order, so htons(port) is not required
 214     pr->rule.dst.xport.range.port[0] = port;
 215     pr->rule.dst.xport.range.op = PF_OP_EQ;
 216
 217     strlcpy( pr->rule.ifname, interfaceName, sizeof( pr->rule.ifname ) );
 218
 219     pr->rule.action = PF_PASS;
 220     pr->rule.direction = PF_IN;
 221     pr->rule.keep_state = 1;
 222     pr->rule.af = AF_INET6;
 223     pr->rule.proto = protocol;
 224     pr->rule.extfilter = PF_EXTFILTER_APD;
 225 }
 226
 227 // allow inbound traffice on the Bonjour port (5353) and the specified port and protocol
 228 int P2PPacketFilterAddBonjourRuleSet(const char * interfaceName, u_int16_t port, u_int16_t protocol )
 229 {
 230     int result;
 231     u_int32_t ticket, poolTicket;
 232     int devFD = -1;
 233         char * anchorPath = MDNS_ANCHOR_PATH;
 234
 235     result = openPFDevice( &devFD );
 236     require( result == 0, exit );
 237
 238     result = getTicket( devFD, &ticket, anchorPath );
 239     require( result == 0, exit );
 240
 241     result = getPoolTicket( devFD, &poolTicket );
 242     require( result == 0, exit );
 243
 244     struct pfioc_rule pr;
 245
 246     // allow inbound Bonjour traffice to port 5353
 247     initBonjourRule( &pr, interfaceName, ticket, poolTicket, anchorPath);
 248
 249     result = addRule( devFD, &pr );
 250     require( result == 0, exit );
 251
 252     // open inbound port for service
 253     initPortRule( &pr, interfaceName, ticket, poolTicket, anchorPath, port, protocol );
 254
 255     result = addRule( devFD, &pr );
 256     require( result == 0, exit );
 257
 258     // allow outbound TCP connections and return traffic for those connections
 259     initOutboundTCPRule( &pr, interfaceName, ticket, poolTicket, anchorPath);
 260
 261     result = addRule( devFD, &pr );
 262     require( result == 0, exit );
 263
 264     result = commitChange( devFD, ticket, anchorPath );
 265     require( result == 0, exit );
 266
 267 exit:
 268
 269     if( devFD >= 0 )
 270         close( devFD );
 271
 272     return result;
 273 }
 274
 275 int P2PPacketFilterClearBonjourRules()
 276 {
 277         int result;
 278         int pfDev = -1;
 279         u_int32_t ticket;
 280         char * anchorPath = MDNS_ANCHOR_PATH;
 281
 282         result = openPFDevice( &pfDev );
 283         require( result == 0, exit );
 284
 285         result = getTicket( pfDev, &ticket, anchorPath );
 286         require( result == 0, exit );
 287
 288         result = commitChange( pfDev, ticket, anchorPath );
 289
 290 exit:
 291
 292         if( pfDev >= 0 )
 293                 close( pfDev );
 294
 295         return result;
 296 }
 297