@@ -130,5 +130,6 @@ extern void ip_mc_unmap(struct in_device *);
extern void ip_mc_remap(struct in_device *);
extern void ip_mc_dec_group(struct in_device *in_dev, __be32 addr);
extern void ip_mc_inc_group(struct in_device *in_dev, __be32 addr);
+int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed);
#endif
@@ -3404,6 +3404,9 @@ static inline void skb_checksum_none_assert(const struct sk_buff *skb)
bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
+int skb_checksum_trimmed(struct sk_buff *skb, unsigned int transport_len,
+ __sum16(*skb_check_func)(struct sk_buff *skb),
+ struct sk_buff **skb_trimmed);
u32 skb_get_poff(const struct sk_buff *skb);
u32 __skb_get_poff(const struct sk_buff *skb, void *data,
@@ -142,6 +142,7 @@ void ipv6_mc_unmap(struct inet6_dev *idev);
void ipv6_mc_remap(struct inet6_dev *idev);
void ipv6_mc_init_dev(struct inet6_dev *idev);
void ipv6_mc_destroy_dev(struct inet6_dev *idev);
+int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed);
void addrconf_dad_failure(struct inet6_ifaddr *ifp);
bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
@@ -975,9 +975,6 @@ static int br_ip4_multicast_igmp3_report(struct net_bridge *br,
int err = 0;
__be32 group;
- if (!pskb_may_pull(skb, sizeof(*ih)))
- return -EINVAL;
-
ih = igmpv3_report_hdr(skb);
num = ntohs(ih->ngrec);
len = sizeof(*ih);
@@ -1248,25 +1245,14 @@ static int br_ip4_multicast_query(struct net_bridge *br,
max_delay = 10 * HZ;
group = 0;
}
- } else {
- if (!pskb_may_pull(skb, sizeof(struct igmpv3_query))) {
- err = -EINVAL;
- goto out;
- }
-
+ } else if (skb->len >= sizeof(*ih3)) {
ih3 = igmpv3_query_hdr(skb);
if (ih3->nsrcs)
goto out;
max_delay = ih3->code ?
IGMPV3_MRC(ih3->code) * (HZ / IGMP_TIMER_SCALE) : 1;
- }
-
- /* RFC2236+RFC3376 (IGMPv2+IGMPv3) require the multicast link layer
- * all-systems destination addresses (224.0.0.1) for general queries
- */
- if (!group && iph->daddr != htonl(INADDR_ALLHOSTS_GROUP)) {
- err = -EINVAL;
+ } else {
goto out;
}
@@ -1329,12 +1315,6 @@ static int br_ip6_multicast_query(struct net_bridge *br,
(port && port->state == BR_STATE_DISABLED))
goto out;
- /* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */
- if (!(ipv6_addr_type(&ip6h->saddr) & IPV6_ADDR_LINKLOCAL)) {
- err = -EINVAL;
- goto out;
- }
-
if (skb->len == sizeof(*mld)) {
if (!pskb_may_pull(skb, sizeof(*mld))) {
err = -EINVAL;
@@ -1358,14 +1338,6 @@ static int br_ip6_multicast_query(struct net_bridge *br,
is_general_query = group && ipv6_addr_any(group);
- /* RFC2710+RFC3810 (MLDv1+MLDv2) require the multicast link layer
- * all-nodes destination address (ff02::1) for general queries
- */
- if (is_general_query && !ipv6_addr_is_ll_all_nodes(&ip6h->daddr)) {
- err = -EINVAL;
- goto out;
- }
-
if (is_general_query) {
saddr.proto = htons(ETH_P_IPV6);
saddr.u.ip6 = ip6h->saddr;
@@ -1557,66 +1529,22 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br,
struct sk_buff *skb,
u16 vid)
{
- struct sk_buff *skb2 = skb;
- const struct iphdr *iph;
+ struct sk_buff *skb_trimmed = NULL;
struct igmphdr *ih;
- unsigned int len;
- unsigned int offset;
int err;
- /* We treat OOM as packet loss for now. */
- if (!pskb_may_pull(skb, sizeof(*iph)))
- return -EINVAL;
-
- iph = ip_hdr(skb);
-
- if (iph->ihl < 5 || iph->version != 4)
- return -EINVAL;
-
- if (!pskb_may_pull(skb, ip_hdrlen(skb)))
- return -EINVAL;
-
- iph = ip_hdr(skb);
+ err = ip_mc_check_igmp(skb, &skb_trimmed);
- if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
- return -EINVAL;
-
- if (iph->protocol != IPPROTO_IGMP) {
- if (!ipv4_is_local_multicast(iph->daddr))
+ if (err == -ENOMSG) {
+ if (!ipv4_is_local_multicast(ip_hdr(skb)->daddr))
BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
return 0;
+ } else if (err < 0) {
+ return err;
}
- len = ntohs(iph->tot_len);
- if (skb->len < len || len < ip_hdrlen(skb))
- return -EINVAL;
-
- if (skb->len > len) {
- skb2 = skb_clone(skb, GFP_ATOMIC);
- if (!skb2)
- return -ENOMEM;
-
- err = pskb_trim_rcsum(skb2, len);
- if (err)
- goto err_out;
- }
-
- len -= ip_hdrlen(skb2);
- offset = skb_network_offset(skb2) + ip_hdrlen(skb2);
- __skb_pull(skb2, offset);
- skb_reset_transport_header(skb2);
-
- err = -EINVAL;
- if (!pskb_may_pull(skb2, sizeof(*ih)))
- goto out;
-
- if (skb_checksum_simple_validate(skb2))
- goto out;
-
- err = 0;
-
BR_INPUT_SKB_CB(skb)->igmp = 1;
- ih = igmp_hdr(skb2);
+ ih = igmp_hdr(skb);
switch (ih->type) {
case IGMP_HOST_MEMBERSHIP_REPORT:
@@ -1625,21 +1553,19 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br,
err = br_ip4_multicast_add_group(br, port, ih->group, vid);
break;
case IGMPV3_HOST_MEMBERSHIP_REPORT:
- err = br_ip4_multicast_igmp3_report(br, port, skb2, vid);
+ err = br_ip4_multicast_igmp3_report(br, port, skb_trimmed, vid);
break;
case IGMP_HOST_MEMBERSHIP_QUERY:
- err = br_ip4_multicast_query(br, port, skb2, vid);
+ err = br_ip4_multicast_query(br, port, skb_trimmed, vid);
break;
case IGMP_HOST_LEAVE_MESSAGE:
br_ip4_multicast_leave_group(br, port, ih->group, vid);
break;
}
-out:
- __skb_push(skb2, offset);
-err_out:
- if (skb2 != skb)
- kfree_skb(skb2);
+ if (skb_trimmed && skb_trimmed != skb)
+ kfree_skb(skb_trimmed);
+
return err;
}
@@ -1649,126 +1575,42 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
struct sk_buff *skb,
u16 vid)
{
- struct sk_buff *skb2;
- const struct ipv6hdr *ip6h;
- u8 icmp6_type;
- u8 nexthdr;
- __be16 frag_off;
- unsigned int len;
- int offset;
+ struct sk_buff *skb_trimmed = NULL;
+ struct mld_msg *mld;
int err;
- if (!pskb_may_pull(skb, sizeof(*ip6h)))
- return -EINVAL;
+ err = ipv6_mc_check_mld(skb, &skb_trimmed);
- ip6h = ipv6_hdr(skb);
-
- /*
- * We're interested in MLD messages only.
- * - Version is 6
- * - MLD has always Router Alert hop-by-hop option
- * - But we do not support jumbrograms.
- */
- if (ip6h->version != 6)
- return 0;
-
- /* Prevent flooding this packet if there is no listener present */
- if (!ipv6_addr_is_ll_all_nodes(&ip6h->daddr))
- BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
-
- if (ip6h->nexthdr != IPPROTO_HOPOPTS ||
- ip6h->payload_len == 0)
- return 0;
-
- len = ntohs(ip6h->payload_len) + sizeof(*ip6h);
- if (skb->len < len)
- return -EINVAL;
-
- nexthdr = ip6h->nexthdr;
- offset = ipv6_skip_exthdr(skb, sizeof(*ip6h), &nexthdr, &frag_off);
-
- if (offset < 0 || nexthdr != IPPROTO_ICMPV6)
+ if (err == -ENOMSG) {
+ if (!ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr))
+ BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
return 0;
-
- /* Okay, we found ICMPv6 header */
- skb2 = skb_clone(skb, GFP_ATOMIC);
- if (!skb2)
- return -ENOMEM;
-
- err = -EINVAL;
- if (!pskb_may_pull(skb2, offset + sizeof(struct icmp6hdr)))
- goto out;
-
- len -= offset - skb_network_offset(skb2);
-
- __skb_pull(skb2, offset);
- skb_reset_transport_header(skb2);
- skb_postpull_rcsum(skb2, skb_network_header(skb2),
- skb_network_header_len(skb2));
-
- icmp6_type = icmp6_hdr(skb2)->icmp6_type;
-
- switch (icmp6_type) {
- case ICMPV6_MGM_QUERY:
- case ICMPV6_MGM_REPORT:
- case ICMPV6_MGM_REDUCTION:
- case ICMPV6_MLD2_REPORT:
- break;
- default:
- err = 0;
- goto out;
- }
-
- /* Okay, we found MLD message. Check further. */
- if (skb2->len > len) {
- err = pskb_trim_rcsum(skb2, len);
- if (err)
- goto out;
- err = -EINVAL;
+ } else if (err < 0) {
+ return err;
}
- ip6h = ipv6_hdr(skb2);
-
- if (skb_checksum_validate(skb2, IPPROTO_ICMPV6, ip6_compute_pseudo))
- goto out;
-
- err = 0;
-
BR_INPUT_SKB_CB(skb)->igmp = 1;
+ mld = (struct mld_msg *)skb_transport_header(skb);
- switch (icmp6_type) {
+ switch (mld->mld_type) {
case ICMPV6_MGM_REPORT:
- {
- struct mld_msg *mld;
- if (!pskb_may_pull(skb2, sizeof(*mld))) {
- err = -EINVAL;
- goto out;
- }
- mld = (struct mld_msg *)skb_transport_header(skb2);
BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
err = br_ip6_multicast_add_group(br, port, &mld->mld_mca, vid);
break;
- }
case ICMPV6_MLD2_REPORT:
- err = br_ip6_multicast_mld2_report(br, port, skb2, vid);
+ err = br_ip6_multicast_mld2_report(br, port, skb_trimmed, vid);
break;
case ICMPV6_MGM_QUERY:
- err = br_ip6_multicast_query(br, port, skb2, vid);
+ err = br_ip6_multicast_query(br, port, skb_trimmed, vid);
break;
case ICMPV6_MGM_REDUCTION:
- {
- struct mld_msg *mld;
- if (!pskb_may_pull(skb2, sizeof(*mld))) {
- err = -EINVAL;
- goto out;
- }
- mld = (struct mld_msg *)skb_transport_header(skb2);
br_ip6_multicast_leave_group(br, port, &mld->mld_mca, vid);
- }
+ break;
}
-out:
- kfree_skb(skb2);
+ if (skb_trimmed && skb_trimmed != skb)
+ kfree_skb(skb_trimmed);
+
return err;
}
#endif
@@ -4012,6 +4012,44 @@ int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
}
EXPORT_SYMBOL(skb_checksum_setup);
+int skb_checksum_trimmed(struct sk_buff *skb, unsigned int transport_len,
+ __sum16(*skb_check_func)(struct sk_buff *skb),
+ struct sk_buff **skb_trimmed)
+{
+ struct sk_buff *skb_chk = skb;
+ unsigned int offset = skb_transport_offset(skb);
+ int ret = 0;
+
+ __skb_pull(skb, offset);
+
+ /* if there's data beyond the IP packet:
+ * avoid it in checksum validation by using a trimmed clone
+ */
+ if (skb->len > transport_len) {
+ skb_chk = skb_clone(skb, GFP_ATOMIC);
+ if (!skb_chk) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ret = pskb_trim_rcsum(skb_chk, transport_len);
+ if (ret)
+ goto out;
+ }
+
+ ret = skb_check_func(skb_chk);
+ if (ret)
+ goto out;
+
+ if (skb_trimmed)
+ *skb_trimmed = skb_chk;
+
+out:
+ __skb_push(skb, offset);
+ return ret;
+}
+EXPORT_SYMBOL(skb_checksum_trimmed);
+
void __skb_warn_lro_forwarding(const struct sk_buff *skb)
{
net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
@@ -1339,6 +1339,158 @@ out:
}
EXPORT_SYMBOL(ip_mc_inc_group);
+static int ip_mc_check_iphdr(struct sk_buff *skb)
+{
+ const struct iphdr *iph;
+ unsigned int len;
+ unsigned int offset = skb_network_offset(skb) + sizeof(*iph);
+
+ if (!pskb_may_pull(skb, offset))
+ return -EINVAL;
+
+ iph = ip_hdr(skb);
+
+ if (iph->version != 4 || ip_hdrlen(skb) < sizeof(*iph))
+ return -EINVAL;
+
+ offset += ip_hdrlen(skb) - sizeof(*iph);
+
+ if (!pskb_may_pull(skb, offset))
+ return -EINVAL;
+
+ iph = ip_hdr(skb);
+
+ if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
+ return -EINVAL;
+
+ len = skb_network_offset(skb) + ntohs(iph->tot_len);
+ if (skb->len < len || len < offset)
+ return -EINVAL;
+
+ skb_set_transport_header(skb, offset);
+
+ return 0;
+}
+
+static int ip_mc_check_igmp_reportv3(struct sk_buff *skb)
+{
+ unsigned int len = skb_transport_offset(skb);
+
+ len += sizeof(struct igmpv3_report);
+
+ return pskb_may_pull(skb, len) ? 0 : -EINVAL;
+}
+
+static int ip_mc_check_igmp_query(struct sk_buff *skb)
+{
+ unsigned int len = skb_transport_offset(skb);
+
+ len += sizeof(struct igmphdr);
+ if (skb->len < len)
+ return -EINVAL;
+
+ /* IGMPv{1,2}? */
+ if (skb->len != len) {
+ /* or IGMPv3? */
+ len += sizeof(struct igmpv3_query) - sizeof(struct igmphdr);
+ if (skb->len < len || !pskb_may_pull(skb, len))
+ return -EINVAL;
+ }
+
+ /* RFC2236+RFC3376 (IGMPv2+IGMPv3) require the multicast link layer
+ * all-systems destination addresses (224.0.0.1) for general queries
+ */
+ if (!igmp_hdr(skb)->group &&
+ ip_hdr(skb)->daddr != htonl(INADDR_ALLHOSTS_GROUP))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int ip_mc_check_igmp_msg(struct sk_buff *skb)
+{
+ switch (igmp_hdr(skb)->type) {
+ case IGMP_HOST_LEAVE_MESSAGE:
+ case IGMP_HOST_MEMBERSHIP_REPORT:
+ case IGMPV2_HOST_MEMBERSHIP_REPORT:
+ /* fall through */
+ return 0;
+ case IGMPV3_HOST_MEMBERSHIP_REPORT:
+ return ip_mc_check_igmp_reportv3(skb);
+ case IGMP_HOST_MEMBERSHIP_QUERY:
+ return ip_mc_check_igmp_query(skb);
+ default:
+ return -ENOMSG;
+ }
+}
+
+static inline __sum16 ip_mc_validate_checksum(struct sk_buff *skb)
+{
+ return skb_checksum_simple_validate(skb);
+}
+
+static int __ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+
+{
+ struct sk_buff *skb_chk = NULL;
+ unsigned int transport_len;
+ unsigned int len = skb_transport_offset(skb) + sizeof(struct igmphdr);
+ int ret;
+
+ if (!pskb_may_pull(skb, len))
+ return -EINVAL;
+
+ transport_len = ntohs(ip_hdr(skb)->tot_len) - ip_hdrlen(skb);
+
+ if (skb_checksum_trimmed(skb, transport_len,
+ ip_mc_validate_checksum, &skb_chk))
+ return -EINVAL;
+
+ ret = ip_mc_check_igmp_msg(skb_chk);
+
+ if (!ret && skb_trimmed)
+ *skb_trimmed = skb_chk;
+ else if (skb_chk && skb_chk != skb)
+ kfree_skb(skb_chk);
+
+ return ret;
+}
+
+/**
+ * ip_mc_check_igmp - checks whether this is a sane IGMP packet
+ * @skb: the skb to validate
+ * @skb_trimmed: to store an skb pointer trimmed to IPv4 packet tail (optional)
+ *
+ * Checks whether an IPv4 packet is a valid IGMP packet. If so sets
+ * skb network and transport headers accordingly and returns zero.
+ *
+ * -EINVAL: A broken packet was detected, i.e. it violates some internet
+ * standard
+ * -ENOMSG: IP header validation succeeded but it is not an IGMP packet.
+ * -ENOMEM: A memory allocation failure happened.
+ *
+ * Optionally, an skb pointer might be provided via skb_trimmed (or set it
+ * to NULL): After parsing an IGMP packet successfully it will point to
+ * an skb which has its tail aligned to the IP packet end. This might
+ * either be the originally provided skb or a trimmed, cloned version if
+ * the skb frame was padded beyond the IP header. A cloned skb allows us
+ * to leave the original skb and its full frame unchanged (which might be
+ * desirable for layer 2 frame jugglers).
+ */
+int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+{
+ int ret = ip_mc_check_iphdr(skb);
+
+ if (ret < 0)
+ return ret;
+
+ if (ip_hdr(skb)->protocol != IPPROTO_IGMP)
+ return -ENOMSG;
+
+ return __ip_mc_check_igmp(skb, skb_trimmed);
+}
+EXPORT_SYMBOL(ip_mc_check_igmp);
+
/*
* Resend IGMP JOIN report; used by netdev notifier.
*/
@@ -48,4 +48,5 @@ obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o
ifneq ($(CONFIG_IPV6),)
obj-$(CONFIG_NET_UDP_TUNNEL) += ip6_udp_tunnel.o
+obj-y += mcast_snoop.o
endif
new file mode 100644
@@ -0,0 +1,198 @@
+/* Copyright (C) 2015: Linus Lüssing <linus.luessing@c0d3.blue>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/skbuff.h>
+#include <net/ipv6.h>
+#include <net/mld.h>
+#include <net/addrconf.h>
+#include <net/ip6_checksum.h>
+
+static int ipv6_mc_check_ip6hdr(struct sk_buff *skb)
+{
+ const struct ipv6hdr *ip6h;
+ unsigned int len;
+ unsigned int offset = skb_network_offset(skb) + sizeof(*ip6h);
+
+ if (!pskb_may_pull(skb, offset))
+ return -EINVAL;
+
+ ip6h = ipv6_hdr(skb);
+
+ if (ip6h->version != 6)
+ return -EINVAL;
+
+ len = offset + ntohs(ip6h->payload_len);
+ if (skb->len < len || len <= offset)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int ipv6_mc_check_exthdrs(struct sk_buff *skb)
+{
+ const struct ipv6hdr *ip6h;
+ unsigned int offset;
+ u8 nexthdr;
+ __be16 frag_off;
+
+ ip6h = ipv6_hdr(skb);
+
+ if (ip6h->nexthdr != IPPROTO_HOPOPTS)
+ return -ENOMSG;
+
+ nexthdr = ip6h->nexthdr;
+ offset = skb_network_offset(skb) + sizeof(*ip6h);
+ offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
+
+ if (offset < 0)
+ return -EINVAL;
+
+ if (nexthdr != IPPROTO_ICMPV6)
+ return -ENOMSG;
+
+ skb_set_transport_header(skb, offset);
+
+ return 0;
+}
+
+static int ipv6_mc_check_mld_reportv2(struct sk_buff *skb)
+{
+ unsigned int len = skb_transport_offset(skb);
+
+ len += sizeof(struct mld2_report);
+
+ return pskb_may_pull(skb, len) ? 0 : -EINVAL;
+}
+
+static int ipv6_mc_check_mld_query(struct sk_buff *skb)
+{
+ struct mld_msg *mld;
+ unsigned int len = skb_transport_offset(skb);
+
+ /* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */
+ if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL))
+ return -EINVAL;
+
+ len += sizeof(struct mld_msg);
+ if (skb->len < len)
+ return -EINVAL;
+
+ /* MLDv1? */
+ if (skb->len != len) {
+ /* or MLDv2? */
+ len += sizeof(struct mld2_query) - sizeof(struct mld_msg);
+ if (skb->len < len || !pskb_may_pull(skb, len))
+ return -EINVAL;
+ }
+
+ mld = (struct mld_msg *)skb_transport_header(skb);
+
+ /* RFC2710+RFC3810 (MLDv1+MLDv2) require the multicast link layer
+ * all-nodes destination address (ff02::1) for general queries
+ */
+ if (ipv6_addr_any(&mld->mld_mca) &&
+ !ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int ipv6_mc_check_mld_msg(struct sk_buff *skb)
+{
+ struct mld_msg *mld = (struct mld_msg *)skb_transport_header(skb);
+
+ switch (mld->mld_type) {
+ case ICMPV6_MGM_REDUCTION:
+ case ICMPV6_MGM_REPORT:
+ /* fall through */
+ return 0;
+ case ICMPV6_MLD2_REPORT:
+ return ipv6_mc_check_mld_reportv2(skb);
+ case ICMPV6_MGM_QUERY:
+ return ipv6_mc_check_mld_query(skb);
+ default:
+ return -ENOMSG;
+ }
+}
+
+static inline __sum16 ipv6_mc_validate_checksum(struct sk_buff *skb)
+{
+ return skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo);
+}
+
+static int __ipv6_mc_check_mld(struct sk_buff *skb,
+ struct sk_buff **skb_trimmed)
+
+{
+ struct sk_buff *skb_chk = NULL;
+ unsigned int transport_len;
+ unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg);
+ int ret;
+
+ if (!pskb_may_pull(skb, len))
+ return -EINVAL;
+
+ transport_len = ipv6_hdr(skb)->payload_len;
+
+ if (skb_checksum_trimmed(skb, transport_len,
+ ipv6_mc_validate_checksum, &skb_chk))
+ return -EINVAL;
+
+ ret = ipv6_mc_check_mld_msg(skb_chk);
+
+ if (!ret && skb_trimmed)
+ *skb_trimmed = skb_chk;
+ else if (skb_chk && skb_chk != skb)
+ kfree_skb(skb_chk);
+
+ return ret;
+}
+
+/**
+ * ipv6_mc_check_mld - checks whether this is a sane MLD packet
+ * @skb: the skb to validate
+ * @skb_trimmed: to store an skb pointer trimmed to IPv6 packet tail (optional)
+ *
+ * Checks whether an IPv6 packet is a valid MLD packet. If so sets
+ * skb network and transport headers accordingly and returns zero.
+ *
+ * -EINVAL: A broken packet was detected, i.e. it violates some internet
+ * standard
+ * -ENOMSG: IP header validation succeeded but it is not an IGMP packet.
+ * -ENOMEM: A memory allocation failure happened.
+ *
+ * Optionally, an skb pointer might be provided via skb_trimmed (or set it
+ * to NULL): After parsing an MLD packet successfully it will point to
+ * an skb which has its tail aligned to the IP packet end. This might
+ * either be the originally provided skb or a trimmed, cloned version if
+ * the skb frame was padded beyond the IP header. A cloned skb allows us
+ * to leave the original skb and its full frame unchanged (which might be
+ * desirable for layer 2 frame jugglers).
+ */
+int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+{
+ int ret;
+
+ ret = ipv6_mc_check_ip6hdr(skb);
+ if (ret < 0)
+ return ret;
+
+ ret = ipv6_mc_check_exthdrs(skb);
+ if (ret < 0)
+ return ret;
+
+ return __ipv6_mc_check_mld(skb, skb_trimmed);
+}
+EXPORT_SYMBOL(ipv6_mc_check_mld);