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-rw-r--r--net/ipv4/igmp.c162
1 files changed, 162 insertions, 0 deletions
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index a3a697f5ffba..651cdf648ec4 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1339,6 +1339,168 @@ 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;
+ unsigned int transport_len;
+ unsigned int len = skb_transport_offset(skb) + sizeof(struct igmphdr);
+ int ret;
+
+ transport_len = ntohs(ip_hdr(skb)->tot_len) - ip_hdrlen(skb);
+
+ skb_get(skb);
+ skb_chk = skb_checksum_trimmed(skb, transport_len,
+ ip_mc_validate_checksum);
+ if (!skb_chk)
+ return -EINVAL;
+
+ if (!pskb_may_pull(skb_chk, len)) {
+ kfree_skb(skb_chk);
+ return -EINVAL;
+ }
+
+ ret = ip_mc_check_igmp_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;
+}
+
+/**
+ * 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 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 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.
*/