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datapath: Avoid accesses past the end of skbuff data in actions.

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Some of the flow actions that modify skbuff data did not check that the
skbuff was long enough before doing so.  This commit fixes that problem.

Previously, the strategy for avoiding this was to only indicate the layer-3
nw_proto field in the flow if the corresponding layer-4 header was fully
present, so that if, for example, nw_proto was IPPROTO_TCP, this meant
that a TCP header was present.  The original motivation for this patch was
to add corresponding code to only indicate a layer-2 dl_type if the
corresponding layer-3 header was fully present.  But I'm now convinced that
this approach is conceptually wrong, because the meaning of a layer-N
header should not be affected by the meaning of a layer-(N+1) header.

This commit switches to a new approach.  Now, when a header is missing, its
fields in the flow are simply zeroed and have no effect on the "type" field
for the outer header.  Responsibility for ensuring that a header is fully
present is now shifted to the actions that wish to modify that header.

Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Ben Pfaff
2010-08-13 10:46:12 -07:00
parent 59a18f80dd
commit ca78c6b69c
4 changed files with 102 additions and 77 deletions
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20
lib/dpif-netdev.c
View File

@@ -1151,19 +1151,25 @@ dp_netdev_set_dl_dst(struct ofpbuf *packet, const uint8_t dl_addr[ETH_ADDR_LEN])
memcpy(eh->eth_dst, dl_addr, sizeof eh->eth_dst);
}
static bool
is_ip(const struct ofpbuf *packet, const flow_t *key)
{
return key->dl_type == htons(ETH_TYPE_IP) && packet->l4;
}
static void
dp_netdev_set_nw_addr(struct ofpbuf *packet, const flow_t *key,
const struct odp_action_nw_addr *a)
{
if (key->dl_type == htons(ETH_TYPE_IP)) {
if (is_ip(packet, key)) {
struct ip_header *nh = packet->l3;
uint32_t *field;
field = a->type == ODPAT_SET_NW_SRC ? &nh->ip_src : &nh->ip_dst;
if (key->nw_proto == IP_TYPE_TCP) {
if (key->nw_proto == IP_TYPE_TCP && packet->l7) {
struct tcp_header *th = packet->l4;
th->tcp_csum = recalc_csum32(th->tcp_csum, *field, a->nw_addr);
} else if (key->nw_proto == IP_TYPE_UDP) {
} else if (key->nw_proto == IP_TYPE_UDP && packet->l7) {
struct udp_header *uh = packet->l4;
if (uh->udp_csum) {
uh->udp_csum = recalc_csum32(uh->udp_csum, *field, a->nw_addr);
@@ -1181,7 +1187,7 @@ static void
dp_netdev_set_nw_tos(struct ofpbuf *packet, const flow_t *key,
const struct odp_action_nw_tos *a)
{
if (key->dl_type == htons(ETH_TYPE_IP)) {
if (is_ip(packet, key)) {
struct ip_header *nh = packet->l3;
uint8_t *field = &nh->ip_tos;
@@ -1198,14 +1204,14 @@ static void
dp_netdev_set_tp_port(struct ofpbuf *packet, const flow_t *key,
const struct odp_action_tp_port *a)
{
if (key->dl_type == htons(ETH_TYPE_IP)) {
if (is_ip(packet, key)) {
uint16_t *field;
if (key->nw_proto == IPPROTO_TCP) {
if (key->nw_proto == IPPROTO_TCP && packet->l7) {
struct tcp_header *th = packet->l4;
field = a->type == ODPAT_SET_TP_SRC ? &th->tcp_src : &th->tcp_dst;
th->tcp_csum = recalc_csum16(th->tcp_csum, *field, a->tp_port);
*field = a->tp_port;
} else if (key->nw_proto == IPPROTO_UDP) {
} else if (key->nw_proto == IPPROTO_UDP && packet->l7) {
struct udp_header *uh = packet->l4;
field = a->type == ODPAT_SET_TP_SRC ? &uh->udp_src : &uh->udp_dst;
uh->udp_csum = recalc_csum16(uh->udp_csum, *field, a->tp_port);