packet.c

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/*
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *   Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: ca50d4546c8e9efff6fb2f73a2ffbf005e9b20e7 $
 *
 * @file protocols/radius/packet.c
 * @brief Functions to deal with fr_packet_t data structures.
 *
 * @copyright 2000-2017 The FreeRADIUS server project
 */
RCSID("$Id: ca50d4546c8e9efff6fb2f73a2ffbf005e9b20e7 $")
 
#include "attrs.h"
 
#include <freeradius-devel/util/udp.h>
#include <freeradius-devel/util/syserror.h>
 
#include <fcntl.h>
 
/*
 *      Some messages get printed out only in debugging mode.
 */
#define FR_DEBUG_STRERROR_PRINTF if (fr_debug_lvl) fr_strerror_printf
 
 
/** Encode a packet
 *
 */
ssize_t fr_packet_encode(fr_packet_t *packet, fr_pair_list_t *list,
                                fr_packet_t const *original, char const *secret)
{
        ssize_t slen;
        fr_radius_ctx_t common = {};
        fr_radius_encode_ctx_t packet_ctx;
 
        /*
         *      A 4K packet, aligned on 64-bits.
         */
        uint8_t data[MAX_PACKET_LEN];
 
#ifndef NDEBUG
        if (fr_debug_lvl >= L_DBG_LVL_4) fr_packet_log_hex(&default_log, packet);
#endif
 
        common.secret = secret;
        common.secret_length = talloc_array_length(secret) - 1;
 
        packet_ctx = (fr_radius_encode_ctx_t) {
                .common = &common,
                .request_authenticator = original ? original->data + 4 : NULL,
                .rand_ctx = (fr_fast_rand_t) {
                        .a = fr_rand(),
                        .b = fr_rand(),
                },
                .request_code = original ? original->data[0] : 0,
                .code = packet->code,
                .id = packet->id,
        };
 
        slen = fr_radius_encode(&FR_DBUFF_TMP(data, sizeof(data)), list, &packet_ctx);
        if (slen < 0) return slen;
 
        /*
         *      Fill in the rest of the fields, and copy the data over
         *      from the local stack to the newly allocated memory.
         *
         *      Yes, all this 'memcpy' is slow, but it means
         *      that we only allocate the minimum amount of
         *      memory for a request.
         */
        packet->data_len = (size_t) slen;
        packet->data = talloc_array(packet, uint8_t, packet->data_len);
        if (!packet->data) {
                fr_strerror_const("Out of memory");
                return -1;
        }
 
        memcpy(packet->data, data, packet->data_len);
 
        return 0;
}
 
/** See if the data pointed to by PTR is a valid RADIUS packet.
 *
 * Packet is not 'const * const' because we may update data_len, if there's more data
 * in the UDP packet than in the RADIUS packet.
 *
 * @param[in] packet            to check.
 * @param[in] max_attributes    to decode.
 * @param[in] require_message_authenticator     to require Message-Authenticator.
 * @param[out] reason           if not NULL, will have the failure reason written to where it points.
 * @return
 *      - True on success.
 *      - False on failure.
 */
bool fr_packet_ok(fr_packet_t *packet, uint32_t max_attributes, bool require_message_authenticator, fr_radius_decode_fail_t *reason)
{
        char host_ipaddr[INET6_ADDRSTRLEN];
 
        if (!fr_radius_ok(packet->data, &packet->data_len, max_attributes, require_message_authenticator, reason)) {
                FR_DEBUG_STRERROR_PRINTF("Bad packet received from host %s",
                                         inet_ntop(packet->socket.inet.src_ipaddr.af, &packet->socket.inet.src_ipaddr.addr,
                                                   host_ipaddr, sizeof(host_ipaddr)));
                return false;
        }
 
        /*
         *      Fill RADIUS header fields
         */
        packet->code = packet->data[0];
        packet->id = packet->data[1];
        memcpy(packet->vector, packet->data + 4, sizeof(packet->vector));
        return true;
}
 
 
/** Verify the Request/Response Authenticator (and Message-Authenticator if present) of a packet
 *
 */
int fr_packet_verify(fr_packet_t *packet, fr_packet_t *original, char const *secret)
{
        char            buffer[INET6_ADDRSTRLEN];
 
        if (!packet->data) return -1;
 
        if (fr_radius_verify(packet->data, original ? original->data + 4 : NULL,
                             (uint8_t const *) secret, talloc_array_length(secret) - 1, false, false) < 0) {
                fr_strerror_printf_push("Received invalid packet from %s",
                                        inet_ntop(packet->socket.inet.src_ipaddr.af, &packet->socket.inet.src_ipaddr.addr,
                                                  buffer, sizeof(buffer)));
                return -1;
        }
 
        return 0;
}
 
 
/** Sign a previously encoded packet
 *
 */
int fr_packet_sign(fr_packet_t *packet, fr_packet_t const *original,
                          char const *secret)
{
        int ret;
 
        ret = fr_radius_sign(packet->data, original ? original->data + 4 : NULL,
                               (uint8_t const *) secret, talloc_array_length(secret) - 1);
        if (ret < 0) return ret;
 
        memcpy(packet->vector, packet->data + 4, RADIUS_AUTH_VECTOR_LENGTH);
        return 0;
}
 
 
/** Wrapper for recvfrom, which handles recvfromto, IPv6, and all possible combinations
 *
 */
static ssize_t rad_recvfrom(int sockfd, fr_packet_t *packet, int flags)
{
        ssize_t                 data_len;
 
        data_len = fr_radius_recv_header(sockfd, &packet->socket.inet.src_ipaddr, &packet->socket.inet.src_port, &packet->code);
        if (data_len < 0) {
                if ((errno == EAGAIN) || (errno == EINTR)) return 0;
                return -1;
        }
 
        if (data_len == 0) return -1; /* invalid packet */
 
        packet->data = talloc_array(packet, uint8_t, data_len);
        if (!packet->data) return -1;
 
        packet->data_len = data_len;
 
        return udp_recv(sockfd, flags, &packet->socket, packet->data, packet->data_len, &packet->timestamp);
}
 
 
/** Receive UDP client requests, and fill in the basics of a fr_packet_t structure
 *
 */
fr_packet_t *fr_packet_recv(TALLOC_CTX *ctx, int fd, int flags, uint32_t max_attributes, bool require_message_authenticator)
{
        ssize_t                 data_len;
        fr_packet_t     *packet;
 
        /*
         *      Allocate the new request data structure
         */
        packet = fr_packet_alloc(ctx, false);
        if (!packet) {
                fr_strerror_const("out of memory");
                return NULL;
        }
 
        data_len = rad_recvfrom(fd, packet, flags);
        if (data_len < 0) {
                FR_DEBUG_STRERROR_PRINTF("Error receiving packet: %s", fr_syserror(errno));
                fr_packet_free(&packet);
                return NULL;
        }
 
#ifdef WITH_VERIFY_PTR
        /*
         *      Double-check that the fields we want are filled in.
         */
        if ((packet->socket.inet.src_ipaddr.af == AF_UNSPEC) ||
            (packet->socket.inet.src_port == 0) ||
            (packet->socket.inet.dst_ipaddr.af == AF_UNSPEC) ||
            (packet->socket.inet.dst_port == 0)) {
                FR_DEBUG_STRERROR_PRINTF("Error receiving packet: %s", fr_syserror(errno));
                fr_packet_free(&packet);
                return NULL;
        }
#endif
 
        packet->data_len = data_len; /* unsigned vs signed */
 
        /*
         *      If the packet is too big, then rad_recvfrom did NOT
         *      allocate memory.  Instead, it just discarded the
         *      packet.
         */
        if (packet->data_len > MAX_PACKET_LEN) {
                FR_DEBUG_STRERROR_PRINTF("Discarding packet: Larger than RFC limitation of 4096 bytes");
                fr_packet_free(&packet);
                return NULL;
        }
 
        /*
         *      Read no data.  Continue.
         *      This check is AFTER the MAX_PACKET_LEN check above, because
         *      if the packet is larger than MAX_PACKET_LEN, we also have
         *      packet->data == NULL
         */
        if ((packet->data_len == 0) || !packet->data) {
                FR_DEBUG_STRERROR_PRINTF("Empty packet: Socket is not ready");
                fr_packet_free(&packet);
                return NULL;
        }
 
        /*
         *      See if it's a well-formed RADIUS packet.
         */
        if (!fr_packet_ok(packet, max_attributes, require_message_authenticator, NULL)) {
                fr_packet_free(&packet);
                return NULL;
        }
 
        /*
         *      Remember which socket we read the packet from.
         */
        packet->socket.fd = fd;
 
        /*
         *      FIXME: Do even more filtering by only permitting
         *      certain IP's.  The problem is that we don't know
         *      how to do this properly for all possible clients...
         */
 
        return packet;
}
 
/** Reply to the request
 *
 * Also attach reply attribute value pairs and any user message provided.
 */
int fr_packet_send(fr_packet_t *packet, fr_pair_list_t *list,
                          fr_packet_t const *original, char const *secret)
{
        /*
         *      Maybe it's a fake packet.  Don't send it.
         */
        if (packet->socket.fd < 0) {
                return 0;
        }
 
        /*
         *  First time through, allocate room for the packet
         */
        if (!packet->data) {
                /*
                 *      Encode the packet.
                 */
                if (fr_packet_encode(packet, list, original, secret) < 0) {
                        return -1;
                }
 
                /*
                 *      Re-sign it, including updating the
                 *      Message-Authenticator.
                 */
                if (fr_packet_sign(packet, original, secret) < 0) {
                        return -1;
                }
 
                /*
                 *      If packet->data points to data, then we print out
                 *      the VP list again only for debugging.
                 */
        }
 
        /*
         *      If the socket is TCP, call write().  Calling sendto()
         *      is allowed on some platforms, but it's not nice.
         */
        if (packet->socket.type == SOCK_STREAM) {
                ssize_t ret;
 
                ret = write(packet->socket.fd, packet->data, packet->data_len);
                if (ret >= 0) return ret;
 
                fr_strerror_printf("sendto failed: %s", fr_syserror(errno));
                return -1;
        }
 
        /*
         *      And send it on it's way.
         *
         *      No need to call fr_socket_addr_swap as apparently
         *      the address is already inverted.
         */
        return udp_send(&packet->socket, 0, packet->data, packet->data_len);
}
 
void _fr_packet_log_hex(fr_log_t const *log, fr_packet_t const *packet, char const *file, int line)
{
        uint8_t const *attr, *end;
        char buffer[1024];
 
        if (!packet->data) return;
 
        fr_log(log, L_DBG, file, line, "  Socket   : %d", packet->socket.fd);
        fr_log(log, L_DBG, file, line, "  Proto    : %d", (packet->socket.type == SOCK_STREAM) ? IPPROTO_TCP : IPPROTO_UDP);
 
        if ((packet->socket.inet.src_ipaddr.af == AF_INET) || (packet->socket.inet.src_ipaddr.af == AF_INET6)) {
                fr_log(log, L_DBG, file, line, "  Src IP   : %pV", fr_box_ipaddr(packet->socket.inet.src_ipaddr));
                fr_log(log, L_DBG, file, line, "  Src Port : %u", packet->socket.inet.src_port);
                fr_log(log, L_DBG, file, line, "  Dst IP   : %pV", fr_box_ipaddr(packet->socket.inet.dst_ipaddr));
                fr_log(log, L_DBG, file, line, "  Dst Port : %u", packet->socket.inet.dst_port);
        }
 
       if ((packet->data[0] > 0) && (packet->data[0] < FR_RADIUS_CODE_MAX)) {
               fr_log(log, L_DBG, file, line, "  Code     : %s", fr_radius_packet_name[packet->data[0]]);
       } else {
               fr_log(log, L_DBG, file, line, "  Code     : %u", packet->data[0]);
       }
 
       fr_log(log, L_DBG, file, line, "  Id       : %u", packet->data[1]);
       fr_log(log, L_DBG, file, line, "  Length   : %u", fr_nbo_to_uint16(packet->data + 2));
       fr_log(log, L_DBG, file, line, "  Vector   : %pH", fr_box_octets(packet->data + 4, RADIUS_AUTH_VECTOR_LENGTH));
 
       if (packet->data_len <= 20) return;
 
       for (attr = packet->data + 20, end = packet->data + packet->data_len;
            attr < end;
            attr += attr[1]) {
               int              i, len, offset = 2;
               unsigned int     vendor = 0;
               char             *p;
               char const       *truncated = "";
 
#ifndef NDEBUG
               if (attr[1] < 2) break; /* Coverity */
#endif
 
               snprintf(buffer, sizeof(buffer), "%02x %02x  ", attr[0], attr[1]);
               p = buffer + strlen(buffer);
               if ((attr[0] == FR_VENDOR_SPECIFIC) &&
                   (attr[1] > 6)) {
                       vendor = fr_nbo_to_uint32(attr + 2);
 
                       snprintf(p, buffer + sizeof(buffer) - p, "%02x%02x%02x%02x (%u)  ",
                                attr[2], attr[3], attr[4], attr[5], vendor);
                       offset = 6;
                       p += strlen(p);
               }
 
               len = attr[1] - offset;
               if (len > 15) {
                       len = 15;
                       truncated = "...";
               }
 
               for (i = 0; i < len; i++) {
                       snprintf(p, buffer + sizeof(buffer) - p, "%02x ", attr[offset + i]);
                       p += 3;
               }
 
               fr_log(log, L_DBG, file, line, "      %s%s\n", buffer, truncated);
       }
}
 
/*
 *      Debug the packet if requested.
 */
void fr_radius_packet_header_log(fr_log_t const *log, fr_packet_t *packet, bool received)
{
        char src_ipaddr[FR_IPADDR_STRLEN];
        char dst_ipaddr[FR_IPADDR_STRLEN];
#ifdef WITH_IFINDEX_NAME_RESOLUTION
        char if_name[IFNAMSIZ];
#endif
 
        if (!log) return;
        if (!packet) return;
 
        /*
         *      Client-specific debugging re-prints the input
         *      packet into the client log.
         *
         *      This really belongs in a utility library
         */
        if (FR_RADIUS_PACKET_CODE_VALID(packet->code)) {
                fr_log(log, L_DBG, __FILE__, __LINE__,
                       "%s %s Id %i from %s%s%s:%i to %s%s%s:%i "
#ifdef WITH_IFINDEX_NAME_RESOLUTION
                       "%s%s%s"
#endif
                       "length %zu\n",
                        received ? "Received" : "Sent",
                        fr_radius_packet_name[packet->code],
                        packet->id,
                        packet->socket.inet.src_ipaddr.af == AF_INET6 ? "[" : "",
                        fr_inet_ntop(src_ipaddr, sizeof(src_ipaddr), &packet->socket.inet.src_ipaddr),
                        packet->socket.inet.src_ipaddr.af == AF_INET6 ? "]" : "",
                        packet->socket.inet.src_port,
                        packet->socket.inet.dst_ipaddr.af == AF_INET6 ? "[" : "",
                        fr_inet_ntop(dst_ipaddr, sizeof(dst_ipaddr), &packet->socket.inet.dst_ipaddr),
                        packet->socket.inet.dst_ipaddr.af == AF_INET6 ? "]" : "",
                        packet->socket.inet.dst_port,
#ifdef WITH_IFINDEX_NAME_RESOLUTION
                        received ? "via " : "",
                        received ? fr_ifname_from_ifindex(if_name, packet->socket.inet.ifindex) : "",
                        received ? " " : "",
#endif
                        packet->data_len);
        } else {
                fr_log(log, L_DBG, __FILE__, __LINE__,
                       "%s code %u Id %i from %s%s%s:%i to %s%s%s:%i "
#ifdef WITH_IFINDEX_NAME_RESOLUTION
                       "%s%s%s"
#endif
                       "length %zu\n",
                        received ? "Received" : "Sent",
                        packet->code,
                        packet->id,
                        packet->socket.inet.src_ipaddr.af == AF_INET6 ? "[" : "",
                        fr_inet_ntop(src_ipaddr, sizeof(src_ipaddr), &packet->socket.inet.src_ipaddr),
                        packet->socket.inet.src_ipaddr.af == AF_INET6 ? "]" : "",
                        packet->socket.inet.src_port,
                        packet->socket.inet.dst_ipaddr.af == AF_INET6 ? "[" : "",
                        fr_inet_ntop(dst_ipaddr, sizeof(dst_ipaddr), &packet->socket.inet.dst_ipaddr),
                        packet->socket.inet.dst_ipaddr.af == AF_INET6 ? "]" : "",
                        packet->socket.inet.dst_port,
#ifdef WITH_IFINDEX_NAME_RESOLUTION
                        received ? "via " : "",
                        received ? fr_ifname_from_ifindex(if_name, packet->socket.inet.ifindex) : "",
                        received ? " " : "",
#endif
                        packet->data_len);
        }
}
 
/*
 *      Debug the packet header and all attributes.  This function is only called by the client code.
 */
void fr_radius_packet_log(fr_log_t const *log, fr_packet_t *packet, fr_pair_list_t *list, bool received)
{
        fr_radius_packet_header_log(log, packet, received);
 
        if (!fr_debug_lvl) return;
 
        /*
         *      If we're auto-adding Message Authenticator, then print
         *      out that we're auto-adding it.
         */
        if (!received) switch (packet->code) {
        case FR_RADIUS_CODE_ACCESS_REQUEST:
        case FR_RADIUS_CODE_STATUS_SERVER:
                if (!fr_pair_find_by_da(list, NULL, attr_message_authenticator)) {
                        fprintf(fr_log_fp, "\tMessage-Authenticator = 0x\n");
                }
                break;
 
        default:
                break;
        }
 
        fr_pair_list_log(log, 4, list);
#ifndef NDEBUG
        if (fr_debug_lvl >= L_DBG_LVL_4) fr_packet_log_hex(log, packet);
#endif
}