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path: root/dhcpv6.c
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Diffstat (limited to 'dhcpv6.c')
-rw-r--r--dhcpv6.c151
1 files changed, 70 insertions, 81 deletions
diff --git a/dhcpv6.c b/dhcpv6.c
index 375ba79..5c9ea88 100644
--- a/dhcpv6.c
+++ b/dhcpv6.c
@@ -24,7 +24,9 @@
#include <unistd.h>
#include <string.h>
#include <time.h>
+#include <limits.h>
+#include "packet.h"
#include "util.h"
#include "passt.h"
#include "tap.h"
@@ -69,6 +71,8 @@ struct opt_hdr {
#endif
#define OPT_SIZE(x) OPT_SIZE_CONV(sizeof(struct opt_##x) - \
sizeof(struct opt_hdr))
+#define OPT_VSIZE(x) (sizeof(struct opt_##x) - \
+ sizeof(struct opt_hdr))
/**
* struct opt_client_id - DHCPv6 Client Identifier option
@@ -265,10 +269,10 @@ static const struct opt_status_code sc_not_on_link = {
/**
* struct resp_not_on_link_t - NotOnLink error (mandated by RFC 8415, 18.3.2.)
- * @uh: UDP header
- * @hdr: DHCP message header
- * @server_id: Server Identifier option
- * @var: Payload: IA_NA from client, status code, client ID
+ * @uh: UDP header
+ * @hdr: DHCP message header
+ * @server_id: Server Identifier option
+ * @var: Payload: IA_NA from client, status code, client ID
*/
static struct resp_not_on_link_t {
struct udphdr uh;
@@ -287,26 +291,30 @@ static struct resp_not_on_link_t {
/**
* dhcpv6_opt() - Get option from DHCPv6 message
- * @o: First option header to check
- * @type: Option type to look up, network order
- * @len: Remaining length, host order, modified on return
+ * @p: Packet pool, single packet with UDP header
+ * @offset: Offset to look at, 0: end of header, set to option start
+ * @type: Option type to look up, network order
*
* Return: pointer to option header, or NULL on malformed or missing option
*/
-static struct opt_hdr *dhcpv6_opt(struct opt_hdr *o, uint16_t type, size_t *len)
+static struct opt_hdr *dhcpv6_opt(struct pool *p, size_t *offset, uint16_t type)
{
- while (*len >= sizeof(struct opt_hdr)) {
- unsigned int opt_len = ntohs(o->l) + sizeof(struct opt_hdr);
+ struct opt_hdr *o;
+ size_t left;
- if (opt_len > *len)
- return NULL;
+ if (!*offset)
+ *offset = sizeof(struct udphdr) + sizeof(struct msg_hdr);
+
+ while ((o = packet_get_try(p, 0, *offset, sizeof(*o), &left))) {
+ unsigned int opt_len = ntohs(o->l) + sizeof(*o);
- *len -= opt_len;
+ if (ntohs(o->l) > left)
+ return NULL;
if (o->t == type)
return o;
- o = (struct opt_hdr *)((uint8_t *)o + opt_len);
+ *offset += opt_len;
}
return NULL;
@@ -314,61 +322,45 @@ static struct opt_hdr *dhcpv6_opt(struct opt_hdr *o, uint16_t type, size_t *len)
/**
* dhcpv6_ia_notonlink() - Check if any IA contains non-appropriate addresses
- * @o: First option header to check for IAs
- * @rem_len: Remaining message length, host order
- * @addr: Address we want to lease to the client
+ * @o: First option header to check for IAs
+ * @rem_len: Remaining message length, host order
+ * @addr: Address we want to lease to the client
*
* Return: pointer to non-appropriate IA_NA or IA_TA, if any, NULL otherwise
*/
-static struct opt_hdr *dhcpv6_ia_notonlink(struct opt_hdr *o, size_t rem_len,
- struct in6_addr *addr)
+static struct opt_hdr *dhcpv6_ia_notonlink(struct pool *p, struct in6_addr *la)
{
- struct opt_hdr *ia, *ia_addr;
char buf[INET6_ADDRSTRLEN];
struct in6_addr *req_addr;
- size_t len;
+ struct opt_hdr *ia, *h;
+ size_t offset;
int ia_type;
ia_type = OPT_IA_NA;
ia_ta:
- len = rem_len;
- ia = o;
-
- while ((ia = dhcpv6_opt(ia, ia_type, &len))) {
- size_t ia_len = ntohs(ia->l);
-
- if (ia_type == OPT_IA_NA) {
- struct opt_ia_na *subopt = (struct opt_ia_na *)ia + 1;
-
- ia_addr = (struct opt_hdr *)subopt;
- } else if (ia_type == OPT_IA_TA) {
- struct opt_ia_ta *subopt = (struct opt_ia_ta *)ia + 1;
-
- ia_addr = (struct opt_hdr *)subopt;
- }
+ offset = 0;
+ while ((ia = dhcpv6_opt(p, &offset, ia_type))) {
+ if (ntohs(ia->l) < OPT_VSIZE(ia_na))
+ return NULL;
- ia_len -= sizeof(struct opt_ia_na) - sizeof(struct opt_hdr);
+ offset += sizeof(struct opt_ia_na);
- while ((ia_addr = dhcpv6_opt(ia_addr, OPT_IAAADR, &ia_len))) {
- struct opt_ia_addr *next;
+ while ((h = dhcpv6_opt(p, &offset, OPT_IAAADR))) {
+ struct opt_ia_addr *opt_addr = (struct opt_ia_addr *)h;
- req_addr = (struct in6_addr *)(ia_addr + 1);
+ if (ntohs(h->l) != OPT_VSIZE(ia_addr))
+ return NULL;
- if (!IN6_ARE_ADDR_EQUAL(addr, req_addr)) {
+ req_addr = &opt_addr->addr;
+ if (!IN6_ARE_ADDR_EQUAL(la, req_addr)) {
info("DHCPv6: requested address %s not on link",
inet_ntop(AF_INET6, req_addr,
buf, sizeof(buf)));
return ia;
}
- next = (struct opt_ia_addr *)ia_addr + 1;
- ia_addr = (struct opt_hdr *)next;
+ offset += sizeof(struct opt_ia_addr);
}
-
- if (!ia_addr)
- break;
-
- ia = ia_addr;
}
if (ia_type == OPT_IA_NA) {
@@ -449,59 +441,58 @@ search:
/**
* dhcpv6() - Check if this is a DHCPv6 message, reply as needed
* @c: Execution context
- * @eh: Packet buffer, Ethernet header
- * @len: Total L2 packet length
+ * @p: Packet pool, single packet starting from UDP header
+ * @saddr: Source IPv6 address of original message
+ * @daddr: Destination IPv6 address of original message
*
* Return: 0 if it's not a DHCPv6 message, 1 if handled, -1 on failure
*/
-int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
+int dhcpv6(struct ctx *c, struct pool *p,
+ const struct in6_addr *saddr, const struct in6_addr *daddr)
{
- struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1);
struct opt_hdr *ia, *bad_ia, *client_id, *server_id;
struct in6_addr *src;
struct msg_hdr *mh;
struct udphdr *uh;
- uint8_t proto;
- size_t mlen;
- size_t n;
+ size_t mlen, n;
- uh = (struct udphdr *)ipv6_l4hdr(ip6h, &proto);
- if (!uh || proto != IPPROTO_UDP || uh->dest != htons(547))
+ uh = packet_get(p, 0, 0, sizeof(*uh), &mlen);
+ if (!uh)
+ return -1;
+
+ if (uh->dest != htons(547))
return 0;
if (c->no_dhcpv6)
return 1;
- if (!IN6_IS_ADDR_MULTICAST(&ip6h->daddr))
+ if (!IN6_IS_ADDR_MULTICAST(daddr))
return -1;
- mlen = len - ((intptr_t)uh - (intptr_t)eh) - sizeof(*uh);
-
- if (mlen != ntohs(uh->len) - sizeof(*uh) ||
- mlen < sizeof(struct msg_hdr))
+ if (mlen + sizeof(*uh) != ntohs(uh->len) || mlen < sizeof(*mh))
return -1;
- c->addr6_ll_seen = ip6h->saddr;
+ c->addr6_ll_seen = *saddr;
if (IN6_IS_ADDR_LINKLOCAL(&c->gw6))
src = &c->gw6;
else
src = &c->addr6_ll;
- mh = (struct msg_hdr *)(uh + 1);
- mlen -= sizeof(struct msg_hdr);
+ mh = packet_get(p, 0, sizeof(*uh), sizeof(*mh), NULL);
+ if (!mh)
+ return -1;
- n = mlen;
- client_id = dhcpv6_opt((struct opt_hdr *)(mh + 1), OPT_CLIENTID, &n);
- if (!client_id || ntohs(client_id->l) > ntohs(OPT_SIZE(client_id)))
+ client_id = dhcpv6_opt(p, &(size_t){ 0 }, OPT_CLIENTID);
+ if (!client_id || ntohs(client_id->l) > OPT_VSIZE(client_id))
return -1;
- n = mlen;
- server_id = dhcpv6_opt((struct opt_hdr *)(mh + 1), OPT_SERVERID, &n);
+ server_id = dhcpv6_opt(p, &(size_t){ 0 }, OPT_SERVERID);
+ if (server_id && ntohs(server_id->l) != OPT_VSIZE(server_id))
+ return -1;
- n = mlen;
- ia = dhcpv6_opt((struct opt_hdr *)(mh + 1), OPT_IA_NA, &n);
- if (ia && ntohs(ia->l) < ntohs(OPT_SIZE(ia_na)))
+ ia = dhcpv6_opt(p, &(size_t){ 0 }, OPT_IA_NA);
+ if (ia && ntohs(ia->l) < MIN(OPT_VSIZE(ia_na), OPT_VSIZE(ia_ta)))
return -1;
resp.hdr.type = TYPE_REPLY;
@@ -516,18 +507,17 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
if (mh->type == TYPE_CONFIRM && server_id)
return -1;
- if ((bad_ia = dhcpv6_ia_notonlink((struct opt_hdr *)(mh + 1),
- mlen, &c->addr6))) {
+ if ((bad_ia = dhcpv6_ia_notonlink(p, &c->addr6))) {
info("DHCPv6: received CONFIRM with inappropriate IA,"
" sending NotOnLink status in REPLY");
- n = ntohs(bad_ia->l) + sizeof(struct opt_hdr);
- bad_ia->l = htons(n - sizeof(struct opt_hdr) +
+ bad_ia->l = htons(OPT_VSIZE(ia_na) +
sizeof(sc_not_on_link));
+ n = sizeof(struct opt_ia_na);
memcpy(resp_not_on_link.var, bad_ia, n);
- memcpy(resp_not_on_link.var + n, &sc_not_on_link,
- sizeof(sc_not_on_link));
+ memcpy(resp_not_on_link.var + n,
+ &sc_not_on_link, sizeof(sc_not_on_link));
n += sizeof(sc_not_on_link);
memcpy(resp_not_on_link.var + n, client_id,
@@ -552,8 +542,7 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
memcmp(&resp.server_id, server_id, sizeof(resp.server_id)))
return -1;
- n = mlen;
- if (ia || dhcpv6_opt((struct opt_hdr *)(mh + 1), OPT_IA_TA, &n))
+ if (ia || dhcpv6_opt(p, &(size_t){ 0 }, OPT_IA_TA))
return -1;
info("DHCPv6: received INFORMATION_REQUEST, sending REPLY");
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-01 07:24:29 +0000