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qemu-e2k/slirp/bootp.c
Aurelien Jarno 8aaf42ed0f slirp: fix unaligned access in bootp code 
Slirp code tries to be smart an avoid data copy by using pointer to
the data. This solution leads to unaligned access, in this case
preq_addr, which is a 32-bit long structure. There is no real point
of avoiding data copy in a such case, as the value itself is smaller
or the same size as a pointer.

The patch replaces pointers to the preq_addr structure by the strcture
itself, and use the address 0.0.0.0 if no address has been requested
(this is not a valid address in such a request). It compares it with
htonl(0L) for correctness reasons, in case a code checker look for such
mistakes. It also uses memcpy() for copying the data, which takes care
of alignement issues.

This fixes an unaligned access on IA64 host while requesting a DHCP
address.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
2011-01-10 10:56:25 +01:00

315 lines
8.9 KiB
C
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/*
* QEMU BOOTP/DHCP server
*
* Copyright (c) 2004 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <slirp.h>
/* XXX: only DHCP is supported */
#define LEASE_TIME (24 * 3600)
static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
#ifdef DEBUG
#define DPRINTF(fmt, ...) \
do if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## __VA_ARGS__); fflush(dfd); } while (0)
#else
#define DPRINTF(fmt, ...) do{}while(0)
#endif
static BOOTPClient *get_new_addr(Slirp *slirp, struct in_addr *paddr,
const uint8_t *macaddr)
{
BOOTPClient *bc;
int i;
for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
bc = &slirp->bootp_clients[i];
if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6))
goto found;
}
return NULL;
found:
bc = &slirp->bootp_clients[i];
bc->allocated = 1;
paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
return bc;
}
static BOOTPClient *request_addr(Slirp *slirp, const struct in_addr *paddr,
const uint8_t *macaddr)
{
uint32_t req_addr = ntohl(paddr->s_addr);
uint32_t dhcp_addr = ntohl(slirp->vdhcp_startaddr.s_addr);
BOOTPClient *bc;
if (req_addr >= dhcp_addr &&
req_addr < (dhcp_addr + NB_BOOTP_CLIENTS)) {
bc = &slirp->bootp_clients[req_addr - dhcp_addr];
if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) {
bc->allocated = 1;
return bc;
}
}
return NULL;
}
static BOOTPClient *find_addr(Slirp *slirp, struct in_addr *paddr,
const uint8_t *macaddr)
{
BOOTPClient *bc;
int i;
for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
if (!memcmp(macaddr, slirp->bootp_clients[i].macaddr, 6))
goto found;
}
return NULL;
found:
bc = &slirp->bootp_clients[i];
bc->allocated = 1;
paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
return bc;
}
static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
struct in_addr *preq_addr)
{
const uint8_t *p, *p_end;
int len, tag;
*pmsg_type = 0;
preq_addr->s_addr = htonl(0L);
p = bp->bp_vend;
p_end = p + DHCP_OPT_LEN;
if (memcmp(p, rfc1533_cookie, 4) != 0)
return;
p += 4;
while (p < p_end) {
tag = p[0];
if (tag == RFC1533_PAD) {
p++;
} else if (tag == RFC1533_END) {
break;
} else {
p++;
if (p >= p_end)
break;
len = *p++;
DPRINTF("dhcp: tag=%d len=%d\n", tag, len);
switch(tag) {
case RFC2132_MSG_TYPE:
if (len >= 1)
*pmsg_type = p[0];
break;
case RFC2132_REQ_ADDR:
if (len >= 4) {
memcpy(&(preq_addr->s_addr), p, 4);
}
break;
default:
break;
}
p += len;
}
}
if (*pmsg_type == DHCPREQUEST && preq_addr->s_addr == htonl(0L) &&
bp->bp_ciaddr.s_addr) {
memcpy(&(preq_addr->s_addr), &bp->bp_ciaddr, 4);
}
}
static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
{
BOOTPClient *bc = NULL;
struct mbuf *m;
struct bootp_t *rbp;
struct sockaddr_in saddr, daddr;
struct in_addr preq_addr;
int dhcp_msg_type, val;
uint8_t *q;
/* extract exact DHCP msg type */
dhcp_decode(bp, &dhcp_msg_type, &preq_addr);
DPRINTF("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type);
if (preq_addr.s_addr != htonl(0L))
DPRINTF(" req_addr=%08x\n", ntohl(preq_addr.s_addr));
else
DPRINTF("\n");
if (dhcp_msg_type == 0)
dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
if (dhcp_msg_type != DHCPDISCOVER &&
dhcp_msg_type != DHCPREQUEST)
return;
/* XXX: this is a hack to get the client mac address */
memcpy(slirp->client_ethaddr, bp->bp_hwaddr, 6);
m = m_get(slirp);
if (!m) {
return;
}
m->m_data += IF_MAXLINKHDR;
rbp = (struct bootp_t *)m->m_data;
m->m_data += sizeof(struct udpiphdr);
memset(rbp, 0, sizeof(struct bootp_t));
if (dhcp_msg_type == DHCPDISCOVER) {
if (preq_addr.s_addr != htonl(0L)) {
bc = request_addr(slirp, &preq_addr, slirp->client_ethaddr);
if (bc) {
daddr.sin_addr = preq_addr;
}
}
if (!bc) {
new_addr:
bc = get_new_addr(slirp, &daddr.sin_addr, slirp->client_ethaddr);
if (!bc) {
DPRINTF("no address left\n");
return;
}
}
memcpy(bc->macaddr, slirp->client_ethaddr, 6);
} else if (preq_addr.s_addr != htonl(0L)) {
bc = request_addr(slirp, &preq_addr, slirp->client_ethaddr);
if (bc) {
daddr.sin_addr = preq_addr;
memcpy(bc->macaddr, slirp->client_ethaddr, 6);
} else {
daddr.sin_addr.s_addr = 0;
}
} else {
bc = find_addr(slirp, &daddr.sin_addr, bp->bp_hwaddr);
if (!bc) {
/* if never assigned, behaves as if it was already
assigned (windows fix because it remembers its address) */
goto new_addr;
}
}
saddr.sin_addr = slirp->vhost_addr;
saddr.sin_port = htons(BOOTP_SERVER);
daddr.sin_port = htons(BOOTP_CLIENT);
rbp->bp_op = BOOTP_REPLY;
rbp->bp_xid = bp->bp_xid;
rbp->bp_htype = 1;
rbp->bp_hlen = 6;
memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
q = rbp->bp_vend;
memcpy(q, rfc1533_cookie, 4);
q += 4;
if (bc) {
DPRINTF("%s addr=%08x\n",
(dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed",
ntohl(daddr.sin_addr.s_addr));
if (dhcp_msg_type == DHCPDISCOVER) {
*q++ = RFC2132_MSG_TYPE;
*q++ = 1;
*q++ = DHCPOFFER;
} else /* DHCPREQUEST */ {
*q++ = RFC2132_MSG_TYPE;
*q++ = 1;
*q++ = DHCPACK;
}
if (slirp->bootp_filename)
snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s",
slirp->bootp_filename);
*q++ = RFC2132_SRV_ID;
*q++ = 4;
memcpy(q, &saddr.sin_addr, 4);
q += 4;
*q++ = RFC1533_NETMASK;
*q++ = 4;
memcpy(q, &slirp->vnetwork_mask, 4);
q += 4;
if (!slirp->restricted) {
*q++ = RFC1533_GATEWAY;
*q++ = 4;
memcpy(q, &saddr.sin_addr, 4);
q += 4;
*q++ = RFC1533_DNS;
*q++ = 4;
memcpy(q, &slirp->vnameserver_addr, 4);
q += 4;
}
*q++ = RFC2132_LEASE_TIME;
*q++ = 4;
val = htonl(LEASE_TIME);
memcpy(q, &val, 4);
q += 4;
if (*slirp->client_hostname) {
val = strlen(slirp->client_hostname);
*q++ = RFC1533_HOSTNAME;
*q++ = val;
memcpy(q, slirp->client_hostname, val);
q += val;
}
} else {
static const char nak_msg[] = "requested address not available";
DPRINTF("nak'ed addr=%08x\n", ntohl(preq_addr->s_addr));
*q++ = RFC2132_MSG_TYPE;
*q++ = 1;
*q++ = DHCPNAK;
*q++ = RFC2132_MESSAGE;
*q++ = sizeof(nak_msg) - 1;
memcpy(q, nak_msg, sizeof(nak_msg) - 1);
q += sizeof(nak_msg) - 1;
}
*q = RFC1533_END;
daddr.sin_addr.s_addr = 0xffffffffu;
m->m_len = sizeof(struct bootp_t) -
sizeof(struct ip) - sizeof(struct udphdr);
udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
}
void bootp_input(struct mbuf *m)
{
struct bootp_t *bp = mtod(m, struct bootp_t *);
if (bp->bp_op == BOOTP_REQUEST) {
bootp_reply(m->slirp, bp);
}
}
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