The Tcpdump Group git mirrors - tcpdump/blob - print-nflog.c

   1 /*
   2  * Copyright (c) 2013, Petar Alilovic,
   3  * Faculty of Electrical Engineering and Computing, University of Zagreb
   4  * All rights reserved
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are met:
   8  *
   9  * * Redistributions of source code must retain the above copyright notice,
  10  *       this list of conditions and the following disclaimer.
  11  * * Redistributions in binary form must reproduce the above copyright
  12  *       notice, this list of conditions and the following disclaimer in the
  13  *       documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
  16  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  18  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
  19  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  20  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  22  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
  25  * DAMAGE.
  26  */
  27
  28 /* \summary: DLT_NFLOG printer */
  29
  30 #include <config.h>
  31
  32 #include "netdissect-stdinc.h"
  33
  34 #include "netdissect.h"
  35 #include "extract.h"
  36
  37 #ifdef DLT_NFLOG
  38
  39 /*
  40  * Structure of an NFLOG header and TLV parts, as described at
  41  * https://www.tcpdump.org/linktypes/LINKTYPE_NFLOG.html
  42  *
  43  * The NFLOG header is big-endian.
  44  *
  45  * The TLV length and type are in host byte order.  The value is either
  46  * big-endian or is an array of bytes in some externally-specified byte
  47  * order (text string, link-layer address, link-layer header, packet
  48  * data, etc.).
  49  */
  50 typedef struct nflog_hdr {
  51         nd_uint8_t      nflog_family;           /* address family */
  52         nd_uint8_t      nflog_version;          /* version */
  53         nd_uint16_t     nflog_rid;              /* resource ID */
  54 } nflog_hdr_t;
  55
  56 #define NFLOG_HDR_LEN sizeof(nflog_hdr_t)
  57
  58 typedef struct nflog_tlv {
  59         nd_uint16_t     tlv_length;             /* tlv length */
  60         nd_uint16_t     tlv_type;               /* tlv type */
  61         /* value follows this */
  62 } nflog_tlv_t;
  63
  64 #define NFLOG_TLV_LEN sizeof(nflog_tlv_t)
  65
  66 typedef struct nflog_packet_hdr {
  67         nd_uint16_t     hw_protocol;    /* hw protocol */
  68         nd_uint8_t      hook;           /* netfilter hook */
  69         nd_byte         pad[1];         /* padding to 32 bits */
  70 } nflog_packet_hdr_t;
  71
  72 typedef struct nflog_hwaddr {
  73         nd_uint16_t     hw_addrlen;     /* address length */
  74         nd_byte         pad[2];         /* padding to 32-bit boundary */
  75         nd_byte         hw_addr[8];     /* address, up to 8 bytes */
  76 } nflog_hwaddr_t;
  77
  78 typedef struct nflog_timestamp {
  79         nd_uint64_t     sec;
  80         nd_uint64_t     usec;
  81 } nflog_timestamp_t;
  82
  83 /*
  84  * TLV types.
  85  */
  86 #define NFULA_PACKET_HDR                1       /* nflog_packet_hdr_t */
  87 #define NFULA_MARK                      2       /* packet mark from skbuff */
  88 #define NFULA_TIMESTAMP                 3       /* nflog_timestamp_t for skbuff's time stamp */
  89 #define NFULA_IFINDEX_INDEV             4       /* ifindex of device on which packet received (possibly bridge group) */
  90 #define NFULA_IFINDEX_OUTDEV            5       /* ifindex of device on which packet transmitted (possibly bridge group) */
  91 #define NFULA_IFINDEX_PHYSINDEV         6       /* ifindex of physical device on which packet received (not bridge group) */
  92 #define NFULA_IFINDEX_PHYSOUTDEV        7       /* ifindex of physical device on which packet transmitted (not bridge group) */
  93 #define NFULA_HWADDR                    8       /* nflog_hwaddr_t for hardware address */
  94 #define NFULA_PAYLOAD                   9       /* packet payload */
  95 #define NFULA_PREFIX                    10      /* text string - null-terminated, count includes NUL */
  96 #define NFULA_UID                       11      /* UID owning socket on which packet was sent/received */
  97 #define NFULA_SEQ                       12      /* sequence number of packets on this NFLOG socket */
  98 #define NFULA_SEQ_GLOBAL                13      /* sequence number of packets on all NFLOG sockets */
  99 #define NFULA_GID                       14      /* GID owning socket on which packet was sent/received */
 100 #define NFULA_HWTYPE                    15      /* ARPHRD_ type of skbuff's device */
 101 #define NFULA_HWHEADER                  16      /* skbuff's MAC-layer header */
 102 #define NFULA_HWLEN                     17      /* length of skbuff's MAC-layer header */
 103
 104 /*
 105  * Define two constants specifically for the two AF code points from the
 106  * LINKTYPE_NFLOG specification above and use these constants instead of
 107  * AF_INET and AF_INET6.  This is the only way to dissect the "wire" encoding
 108  * correctly because some BSD systems define AF_INET6 differently from Linux
 109  * (see af.h) and Haiku defines both AF_INET and AF_INET6 differently from
 110  * Linux.
 111  */
 112 #define NFLOG_AF_INET   2
 113 #define NFLOG_AF_INET6 10
 114 static const struct tok nflog_values[] = {
 115         { NFLOG_AF_INET,        "IPv4" },
 116         { NFLOG_AF_INET6,       "IPv6" },
 117         { 0,                    NULL }
 118 };
 119
 120 static void
 121 nflog_hdr_print(netdissect_options *ndo, const nflog_hdr_t *hdr, u_int length)
 122 {
 123         ND_PRINT("version %u, resource ID %u",
 124             GET_U_1(hdr->nflog_version), GET_BE_U_2(hdr->nflog_rid));
 125
 126         if (!ndo->ndo_qflag) {
 127                 ND_PRINT(", family %s (%u)",
 128                          tok2str(nflog_values, "Unknown",
 129                                  GET_U_1(hdr->nflog_family)),
 130                          GET_U_1(hdr->nflog_family));
 131                 } else {
 132                 ND_PRINT(", %s",
 133                          tok2str(nflog_values,
 134                                  "Unknown NFLOG (0x%02x)",
 135                          GET_U_1(hdr->nflog_family)));
 136                 }
 137
 138         ND_PRINT(", length %u: ", length);
 139 }
 140
 141 void
 142 nflog_if_print(netdissect_options *ndo,
 143                const struct pcap_pkthdr *h, const u_char *p)
 144 {
 145         const nflog_hdr_t *hdr = (const nflog_hdr_t *)p;
 146         uint16_t size;
 147         uint16_t h_size = NFLOG_HDR_LEN;
 148         u_int caplen = h->caplen;
 149         u_int length = h->len;
 150
 151         ndo->ndo_protocol = "nflog";
 152         if (caplen < NFLOG_HDR_LEN) {
 153                 nd_print_trunc(ndo);
 154                 ndo->ndo_ll_hdr_len += caplen;
 155                 return;
 156         }
 157         ndo->ndo_ll_hdr_len += NFLOG_HDR_LEN;
 158
 159         ND_TCHECK_SIZE(hdr);
 160         if (GET_U_1(hdr->nflog_version) != 0) {
 161                 ND_PRINT("version %u (unknown)", GET_U_1(hdr->nflog_version));
 162                 return;
 163         }
 164
 165         if (ndo->ndo_eflag)
 166                 nflog_hdr_print(ndo, hdr, length);
 167
 168         p += NFLOG_HDR_LEN;
 169         length -= NFLOG_HDR_LEN;
 170         caplen -= NFLOG_HDR_LEN;
 171
 172         while (length > 0) {
 173                 const nflog_tlv_t *tlv;
 174
 175                 /* We have some data.  Do we have enough for the TLV header? */
 176                 if (caplen < NFLOG_TLV_LEN)
 177                         goto trunc;     /* No. */
 178
 179                 tlv = (const nflog_tlv_t *) p;
 180                 ND_TCHECK_SIZE(tlv);
 181                 size = GET_HE_U_2(tlv->tlv_length);
 182                 if (size % 4 != 0)
 183                         size += 4 - size % 4;
 184
 185                 /* Is the TLV's length less than the minimum? */
 186                 if (size < NFLOG_TLV_LEN)
 187                         goto trunc;     /* Yes. Give up now. */
 188
 189                 /* Do we have enough data for the full TLV? */
 190                 if (caplen < size)
 191                         goto trunc;     /* No. */
 192
 193                 if (GET_HE_U_2(tlv->tlv_type) == NFULA_PAYLOAD) {
 194                         /*
 195                          * This TLV's data is the packet payload.
 196                          * Skip past the TLV header, and break out
 197                          * of the loop so we print the packet data.
 198                          */
 199                         p += NFLOG_TLV_LEN;
 200                         h_size += NFLOG_TLV_LEN;
 201                         length -= NFLOG_TLV_LEN;
 202                         caplen -= NFLOG_TLV_LEN;
 203                         break;
 204                 }
 205
 206                 p += size;
 207                 h_size += size;
 208                 length -= size;
 209                 caplen -= size;
 210         }
 211
 212         switch (GET_U_1(hdr->nflog_family)) {
 213
 214         case NFLOG_AF_INET:
 215                 ip_print(ndo, p, length);
 216                 break;
 217
 218         case NFLOG_AF_INET6:
 219                 ip6_print(ndo, p, length);
 220                 break;
 221
 222         default:
 223                 if (!ndo->ndo_eflag)
 224                         nflog_hdr_print(ndo, hdr,
 225                                         length + NFLOG_HDR_LEN);
 226
 227                 if (!ndo->ndo_suppress_default_print)
 228                         ND_DEFAULTPRINT(p, caplen);
 229                 break;
 230         }
 231
 232         ndo->ndo_ll_hdr_len += h_size - NFLOG_HDR_LEN;
 233         return;
 234 trunc:
 235         nd_print_trunc(ndo);
 236         ndo->ndo_ll_hdr_len += h_size - NFLOG_HDR_LEN;
 237 }
 238
 239 #endif /* DLT_NFLOG */