granicus.if.org Git - strace/blob - netlink_netfilter.c

   1 /*
   2  * Copyright (c) 2018 Chen Jingpiao <chenjingpiao@gmail.com>
   3  * Copyright (c) 2018 The strace developers.
   4  * All rights reserved.
   5  *
   6  * SPDX-License-Identifier: LGPL-2.1-or-later
   7  */
   8
   9 #include "defs.h"
  10
  11 #ifdef HAVE_LINUX_NETFILTER_NFNETLINK_H
  12
  13 # include "print_fields.h"
  14 # include "nlattr.h"
  15
  16 # include <netinet/in.h>
  17 # include <arpa/inet.h>
  18 # include "netlink.h"
  19 # include <linux/netfilter/nfnetlink.h>
  20
  21 # include "xlat/netfilter_versions.h"
  22 # include "xlat/nl_netfilter_msg_types.h"
  23 # include "xlat/nl_netfilter_subsys_ids.h"
  24
  25 bool
  26 decode_netlink_netfilter(struct tcb *const tcp,
  27                          const struct nlmsghdr *const nlmsghdr,
  28                          const kernel_ulong_t addr,
  29                          const unsigned int len)
  30 {
  31         if (nlmsghdr->nlmsg_type == NLMSG_DONE)
  32                 return false;
  33
  34         struct nfgenmsg nfmsg;
  35
  36         if (len < sizeof(nfmsg))
  37                 printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
  38         else if (!umove_or_printaddr(tcp, addr, &nfmsg)) {
  39                 const uint8_t subsys_id = (uint8_t) (nlmsghdr->nlmsg_type >> 8);
  40                 uint16_t res_id = ntohs(nfmsg.res_id);
  41
  42                 PRINT_FIELD_XVAL("{", nfmsg, nfgen_family, addrfams, "AF_???");
  43                 PRINT_FIELD_XVAL(", ", nfmsg, version, netfilter_versions,
  44                                  "NFNETLINK_???");
  45
  46                 /*
  47                  * Work around wrong endianness in res_id field,
  48                  * see linux commit v4.3-rc1~28^2~47^2~1
  49                  */
  50                 tprints(", res_id=");
  51                 if (subsys_id == NFNL_SUBSYS_NFTABLES
  52                     && res_id == NFNL_SUBSYS_NFTABLES) {
  53                         print_xlat_ex(nfmsg.res_id,
  54                                       "htons(NFNL_SUBSYS_NFTABLES)",
  55                                       XLAT_STYLE_DEFAULT);
  56                 } else if (subsys_id == NFNL_SUBSYS_NFTABLES
  57                            && nfmsg.res_id == NFNL_SUBSYS_NFTABLES) {
  58                         print_xlat_ex(nfmsg.res_id, "NFNL_SUBSYS_NFTABLES",
  59                                       XLAT_STYLE_DEFAULT);
  60                 } else {
  61                         tprintf("htons(%d)", res_id);
  62                 }
  63
  64                 const size_t offset = NLMSG_ALIGN(sizeof(nfmsg));
  65                 if (len > offset) {
  66                         tprints(", ");
  67                         if ((nlmsghdr->nlmsg_type >= NFNL_MSG_BATCH_BEGIN
  68                              && nlmsghdr->nlmsg_type <= NFNL_MSG_BATCH_END)
  69                             || nlmsghdr->nlmsg_type < NLMSG_MIN_TYPE)
  70                                 printstr_ex(tcp, addr + offset,
  71                                             len - offset, QUOTE_FORCE_HEX);
  72                         else
  73                                 decode_nlattr(tcp, addr + offset, len - offset,
  74                                               NULL, NULL, NULL, 0, NULL);
  75                 }
  76         }
  77
  78         return true;
  79 }
  80
  81 #endif /* HAVE_LINUX_NETFILTER_NFNETLINK_H */