src/mac80211.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2012 Daniel Borkmann.
   5  * Subject to the GPL, version 2.
   6  * Parts derived from iw, subject to ISC license.
   7  * Copyright 2007, 2008 Johannes Berg
   8  * Copyright 2007 Andy Lutomirski
   9  * Copyright 2007 Mike Kershaw
  10  * Copyright 2008-2009 Luis R. Rodriguez
  11  */
  12
  13 #define _GNU_SOURCE
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <errno.h>
  17 #include <string.h>
  18 #include <limits.h>
  19 #include <linux/nl80211.h>
  20 #include <netlink/genl/genl.h>
  21 #include <netlink/genl/family.h>
  22 #include <netlink/genl/ctrl.h>
  23 #include <netlink/msg.h>
  24 #include <netlink/attr.h>
  25
  26 #include "die.h"
  27 #include "xutils.h"
  28 #include "mac80211.h"
  29 #include "xmalloc.h"
  30 #include "built_in.h"
  31
  32 #ifdef HAVE_LIBNL_2_x
  33 # define LIBNL_FAILURE  NLE_FAILURE
  34 # define get_nl_errmsg  nl_geterror
  35 #else
  36 # define LIBNL_FAILURE  ENFILE
  37 /* libnl 2.x compatibility code */
  38 # define nl_sock        nl_handle
  39
  40 static inline struct nl_handle *nl_socket_alloc(void)
  41 {
  42         return nl_handle_alloc();
  43 }
  44
  45 static inline void nl_socket_free(struct nl_handle *h)
  46 {
  47         nl_handle_destroy(h);
  48 }
  49
  50 # define get_nl_errmsg  strerror
  51
  52 static inline int __genl_ctrl_alloc_cache(struct nl_handle *h,
  53                                           struct nl_cache **cache)
  54 {
  55         struct nl_cache *tmp = genl_ctrl_alloc_cache(h);
  56         if (!tmp)
  57                 return -ENOMEM;
  58         *cache = tmp;
  59         return 0;
  60 }
  61
  62 # define genl_ctrl_alloc_cache  __genl_ctrl_alloc_cache
  63 #endif /* !HAVE_LIBNL_2_x */
  64
  65 struct nl80211_state {
  66         struct nl_sock *nl_sock;
  67         struct nl_cache *nl_cache;
  68         struct genl_family *nl80211;
  69 };
  70
  71 static void get_mac80211_phydev(const char *device, char *phydev_path,
  72                                 size_t phydev_len)
  73 {
  74         int ret;
  75         char *pathstr;
  76         ssize_t num;
  77
  78         ret = asprintf(&pathstr, "/sys/class/net/%s/phy80211", device);
  79         if (ret < 0)
  80                 panic("Can't generate path name string for /sys/class/net device");
  81
  82         num = readlink(pathstr, phydev_path, phydev_len);
  83         if (num < 0) {
  84                 if (errno == ENOENT || errno == EINVAL)
  85                         panic("It's probably not a mac80211 device!\n");
  86                 panic("Can't readlink %s: %s!\n", pathstr, strerror(errno));
  87         }
  88
  89         xfree(pathstr);
  90         phydev_path[min(num, phydev_len - 1)] = 0;
  91 }
  92
  93 static inline struct nl_msg *nl80211_nlmsg_xalloc(void)
  94 {
  95         struct nl_msg *ret = nlmsg_alloc();
  96         if (!ret)
  97                 panic("Cannot allocate nlmsg memory!\n");
  98         return ret;
  99 }
 100
 101 static inline struct nl_handle *nl80211_nl_socket_xalloc(void)
 102 {
 103         struct nl_handle *ret = nl_socket_alloc();
 104         if (!ret)
 105                 panic("Cannot allocate nl socket memory!\n");
 106         return ret;
 107 }
 108
 109 static void nl80211_init(struct nl80211_state *state, const char *device)
 110 {
 111         int ret;
 112
 113         state->nl_sock = nl80211_nl_socket_xalloc();
 114
 115         ret = genl_connect(state->nl_sock);
 116         if (ret)
 117                 panic("Cannot connect generic netlink!\n");
 118
 119         ret = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache);
 120         if (ret < 0)
 121                 panic("Failed to allocate generic netlink cache: %s!",
 122                       get_nl_errmsg(-ret));
 123
 124         state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211");
 125         if (!state->nl80211)
 126                 panic("nl80211 not found in netlink cache!\n");
 127 }
 128
 129 static void nl80211_cleanup(struct nl80211_state *state)
 130 {
 131         genl_family_put(state->nl80211);
 132
 133         nl_cache_free(state->nl_cache);
 134         nl_socket_free(state->nl_sock);
 135 }
 136
 137 static int nl80211_add_mon_if(struct nl80211_state *state, const char *device,
 138                               const char *mondevice)
 139 {
 140         int ifindex, ret;
 141         struct nl_msg *msg;
 142
 143         ifindex = device_ifindex(device);
 144
 145         msg = nl80211_nlmsg_xalloc();
 146
 147         genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
 148                     0, NL80211_CMD_NEW_INTERFACE, 0);
 149
 150         NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
 151         NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice);
 152         NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR);
 153
 154         ret = nl_send_auto_complete(state->nl_sock, msg);
 155         if (ret < 0) {
 156                 if (ret == -LIBNL_FAILURE) {
 157                         nlmsg_free(msg);
 158                         return -EBUSY;
 159                 }
 160
 161                 panic("Cannot send_auto_complete!\n");
 162         }
 163
 164         ret = nl_wait_for_ack(state->nl_sock);
 165         if (ret < 0) {
 166                 if (ret == -LIBNL_FAILURE) {
 167                         nlmsg_free(msg);
 168                         return -EBUSY;
 169                 }
 170
 171                 panic("Waiting for netlink ack failed!\n");
 172         }
 173
 174         nlmsg_free(msg);
 175         return 0;
 176
 177 nla_put_failure:
 178         panic("nla put failure!\n");
 179         return -EIO; /* dummy */
 180 }
 181
 182 static int nl80211_del_mon_if(struct nl80211_state *state, const char *device,
 183                               const char *mondevice)
 184 {
 185         int ifindex, ret;
 186         struct nl_msg *msg;
 187
 188         ifindex = device_ifindex(mondevice);
 189
 190         msg = nl80211_nlmsg_xalloc();
 191
 192         genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
 193                     0, NL80211_CMD_DEL_INTERFACE, 0);
 194
 195         NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
 196
 197         ret = nl_send_auto_complete(state->nl_sock, msg);
 198         if (ret < 0)
 199                 panic("Cannot send_auto_complete!\n");
 200
 201         ret = nl_wait_for_ack(state->nl_sock);
 202         if (ret < 0)
 203                 panic("Waiting for netlink ack failed!\n");
 204
 205         nlmsg_free(msg);
 206         return 0;
 207
 208 nla_put_failure:
 209         panic("nla put failure!\n");
 210         return -EIO; /* dummy */
 211 }
 212
 213 void enter_rfmon_mac80211(const char *device, char **mondev)
 214 {
 215         int ret;
 216         short flags;
 217         uint32_t n;
 218         char phydev_path[256];
 219         struct nl80211_state nlstate;
 220
 221         /* XXX: is this already a monN device? */
 222         get_mac80211_phydev(device, phydev_path, sizeof(phydev_path));
 223         nl80211_init(&nlstate, device);
 224
 225         for (n = 0; n < UINT_MAX; n++) {
 226                 char mondevice[32];
 227
 228                 slprintf(mondevice, sizeof(mondevice), "mon%u", n);
 229                 ret = nl80211_add_mon_if(&nlstate, device, mondevice);
 230                 if (ret == 0) {
 231                         *mondev = xstrdup(mondevice);
 232
 233                         flags = device_get_flags(*mondev);
 234                         flags |= IFF_UP | IFF_RUNNING;
 235                         device_set_flags(*mondev, flags);
 236
 237                         nl80211_cleanup(&nlstate);
 238                         return;
 239                 }
 240         }
 241
 242         panic("No free monN interfaces!\n");
 243 }
 244
 245 void leave_rfmon_mac80211(const char *device, const char *mondev)
 246 {
 247         short flags;
 248         struct nl80211_state nlstate;
 249
 250         flags = device_get_flags(mondev);
 251         flags &= ~(IFF_UP | IFF_RUNNING);
 252         device_set_flags(mondev, flags);
 253
 254         nl80211_init(&nlstate, device);
 255         nl80211_del_mon_if(&nlstate, device, mondev);
 256         nl80211_cleanup(&nlstate);
 257 }