2019-05-30 01:57:57 +02:00
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// SPDX-License-Identifier: GPL-2.0-only
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2015-05-02 14:01:07 +02:00
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/* Copyright (C) 2010: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
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* Copyright (C) 2015: Linus Lüssing <linus.luessing@c0d3.blue>
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*
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* Based on the MLD support added to br_multicast.c by YOSHIFUJI Hideaki.
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*/
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#include <linux/skbuff.h>
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#include <net/ipv6.h>
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#include <net/mld.h>
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#include <net/addrconf.h>
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#include <net/ip6_checksum.h>
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static int ipv6_mc_check_ip6hdr(struct sk_buff *skb)
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{
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const struct ipv6hdr *ip6h;
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unsigned int len;
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unsigned int offset = skb_network_offset(skb) + sizeof(*ip6h);
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if (!pskb_may_pull(skb, offset))
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return -EINVAL;
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ip6h = ipv6_hdr(skb);
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if (ip6h->version != 6)
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return -EINVAL;
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len = offset + ntohs(ip6h->payload_len);
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if (skb->len < len || len <= offset)
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return -EINVAL;
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2019-01-21 07:26:28 +01:00
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skb_set_transport_header(skb, offset);
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2015-05-02 14:01:07 +02:00
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return 0;
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}
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static int ipv6_mc_check_exthdrs(struct sk_buff *skb)
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{
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const struct ipv6hdr *ip6h;
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2015-05-05 00:19:35 +02:00
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int offset;
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2015-05-02 14:01:07 +02:00
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u8 nexthdr;
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__be16 frag_off;
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ip6h = ipv6_hdr(skb);
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if (ip6h->nexthdr != IPPROTO_HOPOPTS)
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return -ENOMSG;
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nexthdr = ip6h->nexthdr;
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offset = skb_network_offset(skb) + sizeof(*ip6h);
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offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
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if (offset < 0)
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return -EINVAL;
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if (nexthdr != IPPROTO_ICMPV6)
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return -ENOMSG;
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skb_set_transport_header(skb, offset);
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return 0;
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}
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static int ipv6_mc_check_mld_reportv2(struct sk_buff *skb)
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{
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unsigned int len = skb_transport_offset(skb);
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len += sizeof(struct mld2_report);
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2019-01-21 07:26:26 +01:00
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return ipv6_mc_may_pull(skb, len) ? 0 : -EINVAL;
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2015-05-02 14:01:07 +02:00
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}
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static int ipv6_mc_check_mld_query(struct sk_buff *skb)
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{
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2019-01-21 07:26:26 +01:00
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unsigned int transport_len = ipv6_transport_len(skb);
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2015-05-02 14:01:07 +02:00
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struct mld_msg *mld;
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2019-01-21 07:26:26 +01:00
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unsigned int len;
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2015-05-02 14:01:07 +02:00
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/* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */
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if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL))
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return -EINVAL;
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/* MLDv1? */
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2019-01-21 07:26:26 +01:00
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if (transport_len != sizeof(struct mld_msg)) {
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2015-05-02 14:01:07 +02:00
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/* or MLDv2? */
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2019-01-21 07:26:26 +01:00
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if (transport_len < sizeof(struct mld2_query))
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return -EINVAL;
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len = skb_transport_offset(skb) + sizeof(struct mld2_query);
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if (!ipv6_mc_may_pull(skb, len))
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2015-05-02 14:01:07 +02:00
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return -EINVAL;
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}
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mld = (struct mld_msg *)skb_transport_header(skb);
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/* RFC2710+RFC3810 (MLDv1+MLDv2) require the multicast link layer
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* all-nodes destination address (ff02::1) for general queries
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*/
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if (ipv6_addr_any(&mld->mld_mca) &&
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!ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr))
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return -EINVAL;
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return 0;
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}
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static int ipv6_mc_check_mld_msg(struct sk_buff *skb)
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{
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2019-01-21 07:26:26 +01:00
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unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg);
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struct mld_msg *mld;
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if (!ipv6_mc_may_pull(skb, len))
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return -EINVAL;
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mld = (struct mld_msg *)skb_transport_header(skb);
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2015-05-02 14:01:07 +02:00
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switch (mld->mld_type) {
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case ICMPV6_MGM_REDUCTION:
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case ICMPV6_MGM_REPORT:
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return 0;
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case ICMPV6_MLD2_REPORT:
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return ipv6_mc_check_mld_reportv2(skb);
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case ICMPV6_MGM_QUERY:
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return ipv6_mc_check_mld_query(skb);
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default:
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return -ENOMSG;
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}
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}
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static inline __sum16 ipv6_mc_validate_checksum(struct sk_buff *skb)
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{
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return skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo);
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}
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2019-01-21 07:26:28 +01:00
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int ipv6_mc_check_icmpv6(struct sk_buff *skb)
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2015-05-02 14:01:07 +02:00
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{
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2019-01-21 07:26:26 +01:00
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unsigned int len = skb_transport_offset(skb) + sizeof(struct icmp6hdr);
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unsigned int transport_len = ipv6_transport_len(skb);
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struct sk_buff *skb_chk;
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2015-05-02 14:01:07 +02:00
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2019-01-21 07:26:26 +01:00
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if (!ipv6_mc_may_pull(skb, len))
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return -EINVAL;
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2015-05-02 14:01:07 +02:00
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skb_chk = skb_checksum_trimmed(skb, transport_len,
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ipv6_mc_validate_checksum);
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if (!skb_chk)
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2019-01-21 07:26:26 +01:00
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return -EINVAL;
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2015-08-13 05:54:07 +02:00
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2019-01-21 07:26:26 +01:00
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if (skb_chk != skb)
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2015-08-13 05:54:07 +02:00
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kfree_skb(skb_chk);
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2019-01-21 07:26:26 +01:00
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return 0;
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2015-05-02 14:01:07 +02:00
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}
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2019-01-21 07:26:28 +01:00
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EXPORT_SYMBOL(ipv6_mc_check_icmpv6);
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2015-05-02 14:01:07 +02:00
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/**
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* ipv6_mc_check_mld - checks whether this is a sane MLD packet
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* @skb: the skb to validate
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*
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* Checks whether an IPv6 packet is a valid MLD packet. If so sets
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2015-08-13 05:54:07 +02:00
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* skb transport header accordingly and returns zero.
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2015-05-02 14:01:07 +02:00
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*
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* -EINVAL: A broken packet was detected, i.e. it violates some internet
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* standard
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* -ENOMSG: IP header validation succeeded but it is not an MLD packet.
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* -ENOMEM: A memory allocation failure happened.
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*
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2015-08-13 05:54:07 +02:00
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* Caller needs to set the skb network header and free any returned skb if it
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* differs from the provided skb.
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2015-05-02 14:01:07 +02:00
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*/
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2019-01-21 07:26:25 +01:00
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int ipv6_mc_check_mld(struct sk_buff *skb)
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2015-05-02 14:01:07 +02:00
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{
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int ret;
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ret = ipv6_mc_check_ip6hdr(skb);
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if (ret < 0)
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return ret;
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ret = ipv6_mc_check_exthdrs(skb);
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if (ret < 0)
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return ret;
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2019-01-21 07:26:26 +01:00
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ret = ipv6_mc_check_icmpv6(skb);
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if (ret < 0)
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return ret;
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return ipv6_mc_check_mld_msg(skb);
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2015-05-02 14:01:07 +02:00
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}
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EXPORT_SYMBOL(ipv6_mc_check_mld);
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