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-rw-r--r--net/ipv6/mcast_snoop.c213
1 files changed, 213 insertions, 0 deletions
diff --git a/net/ipv6/mcast_snoop.c b/net/ipv6/mcast_snoop.c
new file mode 100644
index 000000000000..df8afe5ab31e
--- /dev/null
+++ b/net/ipv6/mcast_snoop.c
@@ -0,0 +1,213 @@
+/* Copyright (C) 2010: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+ * 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/>.
+ *
+ *
+ * Based on the MLD support added to br_multicast.c by YOSHIFUJI Hideaki.
+ */
+
+#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;
+ 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;
+
+ transport_len = ntohs(ipv6_hdr(skb)->payload_len);
+ transport_len -= skb_transport_offset(skb) - sizeof(struct ipv6hdr);
+
+ skb_get(skb);
+ skb_chk = skb_checksum_trimmed(skb, transport_len,
+ ipv6_mc_validate_checksum);
+ if (!skb_chk)
+ return -EINVAL;
+
+ if (!pskb_may_pull(skb_chk, len)) {
+ kfree_skb(skb_chk);
+ return -EINVAL;
+ }
+
+ ret = ipv6_mc_check_mld_msg(skb_chk);
+ if (ret) {
+ kfree_skb(skb_chk);
+ return ret;
+ }
+
+ if (skb_trimmed)
+ *skb_trimmed = skb_chk;
+ else
+ kfree_skb(skb_chk);
+
+ return 0;
+}
+
+/**
+ * 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 MLD 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 had data beyond the IP packet. A cloned skb allows us
+ * to leave the original skb and its full frame unchanged (which might be
+ * desirable for layer 2 frame jugglers).
+ *
+ * The caller needs to release a reference count from any returned skb_trimmed.
+ */
+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);