bsd/netinet/kpi_ipfilter.h

   1 /*
   2  * Copyright (c) 2008 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*!
  29         @header kpi_ipfilter.h
  30         This header defines an API to attach IP filters. IP filters may be
  31         attached to intercept either IPv4 or IPv6 packets. The filters can
  32         intercept all IP packets in to and out of the host regardless of
  33         interface.
  34  */
  35
  36 #ifndef __KPI_IPFILTER__
  37 #define __KPI_IPFILTER__
  38
  39 #include <sys/kernel_types.h>
  40
  41 /*
  42  * ipf_pktopts
  43  *
  44  * Options for outgoing packets. The options need to be preserved when
  45  * re-injecting a packet.
  46  */
  47 struct ipf_pktopts {
  48         u_int32_t                       ippo_flags;
  49         ifnet_t                         ippo_mcast_ifnet;
  50         int                             ippo_mcast_loop;
  51         u_int8_t                        ippo_mcast_ttl;
  52 };
  53 #define IPPOF_MCAST_OPTS 0x1
  54
  55 typedef struct ipf_pktopts *ipf_pktopts_t;
  56
  57 __BEGIN_DECLS
  58
  59 /*!
  60         @typedef ipf_input_func
  61
  62         @discussion ipf_input_func is used to filter incoming ip packets.
  63                 The IP filter is called for packets from all interfaces. The
  64                 filter is called between when the general IP processing is
  65                 handled and when the packet is passed up to the next layer
  66                 protocol such as udp or tcp. In the case of encapsulation, such
  67                 as UDP in ESP (IPSec), your filter will be called once for ESP
  68                 and then again for UDP. This will give your filter an
  69                 opportunity to process the ESP header as well as the decrypted
  70                 packet. Offset and protocol are used to determine where in the
  71                 packet processing is currently occuring. If you're only
  72                 interested in TCP or UDP packets, just return 0 if protocol
  73                 doesn't match TCP or UDP.
  74         @param cookie The cookie specified when your filter was attached.
  75         @param data The reassembled ip packet, data will start at the ip
  76                 header.
  77         @param offset An offset to the next header
  78                 (udp/tcp/icmp/esp/etc...).
  79         @param protocol The protocol type (udp/tcp/icmp/etc...) of the IP packet
  80         @result Return:
  81                 0 - The caller will continue with normal processing of the
  82                         packet.
  83                 EJUSTRETURN - The caller will stop processing the packet,
  84                         the packet will not be freed.
  85                 Anything Else - The caller will free the packet and stop
  86                         processing.
  87 */
  88 typedef errno_t (*ipf_input_func)(void *cookie, mbuf_t *data, int offset,
  89     u_int8_t protocol);
  90
  91 /*!
  92         @typedef ipf_output_func
  93
  94         @discussion ipf_output_func is used to filter outbound ip packets.
  95                 The IP filter is called for packets to all interfaces. The
  96                 filter is called before fragmentation and IPSec processing. If
  97                 you need to change the destination IP address, call
  98                 ipf_inject_output and return EJUSTRETURN.
  99         @param cookie The cookie specified when your filter was attached.
 100         @param data The ip packet, will contain an IP header followed by the
 101                 rest of the IP packet.
 102         @result Return:
 103                 0 - The caller will continue with normal processing of the
 104                         packet.
 105                 EJUSTRETURN - The caller will stop processing the packet,
 106                         the packet will not be freed.
 107                 Anything Else - The caller will free the packet and stop
 108                         processing.
 109 */
 110 typedef errno_t (*ipf_output_func)(void *cookie, mbuf_t *data,
 111     ipf_pktopts_t options);
 112
 113 /*!
 114         @typedef ipf_detach_func
 115
 116         @discussion ipf_detach_func is called to notify your filter that it
 117                 has been detached.
 118         @param cookie The cookie specified when your filter was attached.
 119 */
 120 typedef void (*ipf_detach_func)(void *cookie);
 121
 122 /*!
 123         @typedef ipf_filter
 124         @discussion This structure is used to define an IP filter for
 125                 use with the ipf_addv4 or ipf_addv6 function.
 126         @field cookie A kext defined cookie that will be passed to all
 127                 filter functions.
 128         @field name A filter name used for debugging purposes.
 129         @field ipf_input The filter function to handle inbound packets.
 130         @field ipf_output The filter function to handle outbound packets.
 131         @field ipf_detach The filter function to notify of a detach.
 132 */
 133 struct ipf_filter {
 134         void            *cookie;
 135         const char      *name;
 136         ipf_input_func  ipf_input;
 137         ipf_output_func ipf_output;
 138         ipf_detach_func ipf_detach;
 139 };
 140
 141 struct opaque_ipfilter;
 142 typedef struct opaque_ipfilter *ipfilter_t;
 143
 144 /*!
 145         @function ipf_addv4
 146         @discussion Attaches an IPv4 ip filter.
 147         @param filter A structure defining the filter.
 148         @param filter_ref A reference to the filter used to detach it.
 149         @result 0 on success otherwise the errno error.
 150  */
 151 extern errno_t ipf_addv4(const struct ipf_filter *filter,
 152     ipfilter_t *filter_ref);
 153
 154 /*!
 155         @function ipf_addv6
 156         @discussion Attaches an IPv6 ip filter.
 157         @param filter A structure defining the filter.
 158         @param filter_ref A reference to the filter used to detach it.
 159         @result 0 on success otherwise the errno error.
 160  */
 161 extern errno_t ipf_addv6(const struct ipf_filter *filter,
 162     ipfilter_t *filter_ref);
 163
 164 /*!
 165         @function ipf_remove
 166         @discussion Detaches an IPv4 or IPv6 filter.
 167         @param filter_ref The reference to the filter returned from ipf_addv4 or
 168                 ipf_addv6.
 169         @result 0 on success otherwise the errno error.
 170  */
 171 extern errno_t ipf_remove(ipfilter_t filter_ref);
 172
 173 /*!
 174         @function ipf_inject_input
 175         @discussion Inject an IP packet as though it had just been
 176                 reassembled in ip_input. When re-injecting a packet intercepted
 177                 by the filter's ipf_input function, an IP filter can pass its
 178                 reference to avoid processing the packet twice. This also
 179                 prevents ip filters installed before this filter from
 180                 getting a chance to process the packet. If the filter modified
 181                 the packet, it should not specify the filter ref to give other
 182                 filters a chance to process the new packet.
 183
 184                 Caller is responsible for freeing mbuf chain in the event that
 185                 ipf_inject_input returns an error.
 186         @param data The complete IPv4 or IPv6 packet, receive interface must
 187                 be set.
 188         @param filter_ref The reference to the filter injecting the data
 189         @result 0 on success otherwise the errno error.
 190  */
 191 extern errno_t ipf_inject_input(mbuf_t data, ipfilter_t filter_ref);
 192
 193 /*!
 194         @function ipf_inject_output
 195         @discussion Inject an IP packet as though it had just been sent to
 196                 ip_output. When re-injecting a packet intercepted by the
 197                 filter's ipf_output function, an IP filter can pass its
 198                 reference to avoid processing the packet twice. This also
 199                 prevents ip filters installed before this filter from getting a
 200                 chance to process the packet. If the filter modified the packet,
 201                 it should not specify the filter ref to give other filters a
 202                 chance to process the new packet.
 203         @param data The complete IPv4 or IPv6 packet.
 204         @param filter_ref The reference to the filter injecting the data
 205         @param options Output options for the packet
 206         @result 0 on success otherwise the errno error. ipf_inject_output
 207                 will always free the mbuf.
 208  */
 209 extern errno_t ipf_inject_output(mbuf_t data, ipfilter_t filter_ref,
 210     ipf_pktopts_t options);
 211
 212 __END_DECLS
 213 #endif /* __KPI_IPFILTER__ */