src/l2_packet/l2_packet_privsep.c

   1 /*
   2  * WPA Supplicant - Layer2 packet handling with privilege separation
   3  * Copyright (c) 2007, Jouni Malinen <j@w1.fi>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Alternatively, this software may be distributed under the terms of BSD
  10  * license.
  11  *
  12  * See README and COPYING for more details.
  13  */
  14
  15 #include "includes.h"
  16 #include <sys/un.h>
  17
  18 #include "common.h"
  19 #include "eloop.h"
  20 #include "l2_packet.h"
  21 #include "common/privsep_commands.h"
  22
  23
  24 struct l2_packet_data {
  25         int fd; /* UNIX domain socket for privsep access */
  26         void (*rx_callback)(void *ctx, const u8 *src_addr,
  27                             const u8 *buf, size_t len);
  28         void *rx_callback_ctx;
  29         u8 own_addr[ETH_ALEN];
  30         char *own_socket_path;
  31         struct sockaddr_un priv_addr;
  32 };
  33
  34
  35 static int wpa_priv_cmd(struct l2_packet_data *l2, int cmd,
  36                         const void *data, size_t data_len)
  37 {
  38         struct msghdr msg;
  39         struct iovec io[2];
  40
  41         io[0].iov_base = &cmd;
  42         io[0].iov_len = sizeof(cmd);
  43         io[1].iov_base = (u8 *) data;
  44         io[1].iov_len = data_len;
  45
  46         os_memset(&msg, 0, sizeof(msg));
  47         msg.msg_iov = io;
  48         msg.msg_iovlen = data ? 2 : 1;
  49         msg.msg_name = &l2->priv_addr;
  50         msg.msg_namelen = sizeof(l2->priv_addr);
  51
  52         if (sendmsg(l2->fd, &msg, 0) < 0) {
  53                 perror("L2: sendmsg(cmd)");
  54                 return -1;
  55         }
  56
  57         return 0;
  58 }
  59
  60
  61 int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
  62 {
  63         os_memcpy(addr, l2->own_addr, ETH_ALEN);
  64         return 0;
  65 }
  66
  67
  68 int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
  69                    const u8 *buf, size_t len)
  70 {
  71         struct msghdr msg;
  72         struct iovec io[4];
  73         int cmd = PRIVSEP_CMD_L2_SEND;
  74
  75         io[0].iov_base = &cmd;
  76         io[0].iov_len = sizeof(cmd);
  77         io[1].iov_base = &dst_addr;
  78         io[1].iov_len = ETH_ALEN;
  79         io[2].iov_base = &proto;
  80         io[2].iov_len = 2;
  81         io[3].iov_base = (u8 *) buf;
  82         io[3].iov_len = len;
  83
  84         os_memset(&msg, 0, sizeof(msg));
  85         msg.msg_iov = io;
  86         msg.msg_iovlen = 4;
  87         msg.msg_name = &l2->priv_addr;
  88         msg.msg_namelen = sizeof(l2->priv_addr);
  89
  90         if (sendmsg(l2->fd, &msg, 0) < 0) {
  91                 perror("L2: sendmsg(packet_send)");
  92                 return -1;
  93         }
  94
  95         return 0;
  96 }
  97
  98
  99 static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
 100 {
 101         struct l2_packet_data *l2 = eloop_ctx;
 102         u8 buf[2300];
 103         int res;
 104         struct sockaddr_un from;
 105         socklen_t fromlen = sizeof(from);
 106
 107         os_memset(&from, 0, sizeof(from));
 108         res = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *) &from,
 109                        &fromlen);
 110         if (res < 0) {
 111                 perror("l2_packet_receive - recvfrom");
 112                 return;
 113         }
 114         if (res < ETH_ALEN) {
 115                 wpa_printf(MSG_DEBUG, "L2: Too show packet received");
 116                 return;
 117         }
 118
 119         if (from.sun_family != AF_UNIX ||
 120             os_strncmp(from.sun_path, l2->priv_addr.sun_path,
 121                        sizeof(from.sun_path)) != 0) {
 122                 wpa_printf(MSG_DEBUG, "L2: Received message from unexpected "
 123                            "source");
 124                 return;
 125         }
 126
 127         l2->rx_callback(l2->rx_callback_ctx, buf, buf + ETH_ALEN,
 128                         res - ETH_ALEN);
 129 }
 130
 131
 132 struct l2_packet_data * l2_packet_init(
 133         const char *ifname, const u8 *own_addr, unsigned short protocol,
 134         void (*rx_callback)(void *ctx, const u8 *src_addr,
 135                             const u8 *buf, size_t len),
 136         void *rx_callback_ctx, int l2_hdr)
 137 {
 138         struct l2_packet_data *l2;
 139         char *own_dir = "/tmp";
 140         char *priv_dir = "/var/run/wpa_priv";
 141         size_t len;
 142         static unsigned int counter = 0;
 143         struct sockaddr_un addr;
 144         fd_set rfds;
 145         struct timeval tv;
 146         int res;
 147         u8 reply[ETH_ALEN + 1];
 148         int reg_cmd[2];
 149
 150         l2 = os_zalloc(sizeof(struct l2_packet_data));
 151         if (l2 == NULL)
 152                 return NULL;
 153         l2->rx_callback = rx_callback;
 154         l2->rx_callback_ctx = rx_callback_ctx;
 155
 156         len = os_strlen(own_dir) + 50;
 157         l2->own_socket_path = os_malloc(len);
 158         if (l2->own_socket_path == NULL) {
 159                 os_free(l2);
 160                 return NULL;
 161         }
 162         os_snprintf(l2->own_socket_path, len, "%s/wpa_privsep-l2-%d-%d",
 163                     own_dir, getpid(), counter++);
 164
 165         l2->priv_addr.sun_family = AF_UNIX;
 166         os_snprintf(l2->priv_addr.sun_path, sizeof(l2->priv_addr.sun_path),
 167                     "%s/%s", priv_dir, ifname);
 168
 169         l2->fd = socket(PF_UNIX, SOCK_DGRAM, 0);
 170         if (l2->fd < 0) {
 171                 perror("socket(PF_UNIX)");
 172                 os_free(l2->own_socket_path);
 173                 l2->own_socket_path = NULL;
 174                 os_free(l2);
 175                 return NULL;
 176         }
 177
 178         os_memset(&addr, 0, sizeof(addr));
 179         addr.sun_family = AF_UNIX;
 180         os_strlcpy(addr.sun_path, l2->own_socket_path, sizeof(addr.sun_path));
 181         if (bind(l2->fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
 182                 perror("bind(PF_UNIX)");
 183                 goto fail;
 184         }
 185
 186         reg_cmd[0] = protocol;
 187         reg_cmd[1] = l2_hdr;
 188         if (wpa_priv_cmd(l2, PRIVSEP_CMD_L2_REGISTER, reg_cmd, sizeof(reg_cmd))
 189             < 0) {
 190                 wpa_printf(MSG_ERROR, "L2: Failed to register with wpa_priv");
 191                 goto fail;
 192         }
 193
 194         FD_ZERO(&rfds);
 195         FD_SET(l2->fd, &rfds);
 196         tv.tv_sec = 5;
 197         tv.tv_usec = 0;
 198         res = select(l2->fd + 1, &rfds, NULL, NULL, &tv);
 199         if (res < 0 && errno != EINTR) {
 200                 perror("select");
 201                 goto fail;
 202         }
 203
 204         if (FD_ISSET(l2->fd, &rfds)) {
 205                 res = recv(l2->fd, reply, sizeof(reply), 0);
 206                 if (res < 0) {
 207                         perror("recv");
 208                         goto fail;
 209                 }
 210         } else {
 211                 wpa_printf(MSG_DEBUG, "L2: Timeout while waiting for "
 212                            "registration reply");
 213                 goto fail;
 214         }
 215
 216         if (res != ETH_ALEN) {
 217                 wpa_printf(MSG_DEBUG, "L2: Unexpected registration reply "
 218                            "(len=%d)", res);
 219         }
 220         os_memcpy(l2->own_addr, reply, ETH_ALEN);
 221
 222         eloop_register_read_sock(l2->fd, l2_packet_receive, l2, NULL);
 223
 224         return l2;
 225
 226 fail:
 227         close(l2->fd);
 228         l2->fd = -1;
 229         unlink(l2->own_socket_path);
 230         os_free(l2->own_socket_path);
 231         l2->own_socket_path = NULL;
 232         os_free(l2);
 233         return NULL;
 234 }
 235
 236
 237 void l2_packet_deinit(struct l2_packet_data *l2)
 238 {
 239         if (l2 == NULL)
 240                 return;
 241
 242         if (l2->fd >= 0) {
 243                 wpa_priv_cmd(l2, PRIVSEP_CMD_L2_UNREGISTER, NULL, 0);
 244                 eloop_unregister_read_sock(l2->fd);
 245                 close(l2->fd);
 246         }
 247
 248         if (l2->own_socket_path) {
 249                 unlink(l2->own_socket_path);
 250                 os_free(l2->own_socket_path);
 251         }
 252
 253         os_free(l2);
 254 }
 255
 256
 257 int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
 258 {
 259         /* TODO */
 260         return -1;
 261 }
 262
 263
 264 void l2_packet_notify_auth_start(struct l2_packet_data *l2)
 265 {
 266         wpa_priv_cmd(l2, PRIVSEP_CMD_L2_NOTIFY_AUTH_START, NULL, 0);
 267 }