diff options
Diffstat (limited to 'net/ipv6/mcast_snoop.c')
| -rw-r--r-- | net/ipv6/mcast_snoop.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/net/ipv6/mcast_snoop.c b/net/ipv6/mcast_snoop.c new file mode 100644 index 000000000..04d5fcdfa --- /dev/null +++ b/net/ipv6/mcast_snoop.c @@ -0,0 +1,190 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (C) 2010: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> + * Copyright (C) 2015: Linus Lüssing <linus.luessing@c0d3.blue> + * + * 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; + + skb_set_transport_header(skb, offset); + + 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 ipv6_mc_may_pull(skb, len) ? 0 : -EINVAL; +} + +static int ipv6_mc_check_mld_query(struct sk_buff *skb) +{ + unsigned int transport_len = ipv6_transport_len(skb); + struct mld_msg *mld; + unsigned int len; + + /* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */ + if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) + return -EINVAL; + + /* MLDv1? */ + if (transport_len != sizeof(struct mld_msg)) { + /* or MLDv2? */ + if (transport_len < sizeof(struct mld2_query)) + return -EINVAL; + + len = skb_transport_offset(skb) + sizeof(struct mld2_query); + if (!ipv6_mc_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) +{ + unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg); + struct mld_msg *mld; + + if (!ipv6_mc_may_pull(skb, len)) + return -ENODATA; + + mld = (struct mld_msg *)skb_transport_header(skb); + + switch (mld->mld_type) { + case ICMPV6_MGM_REDUCTION: + case ICMPV6_MGM_REPORT: + 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 -ENODATA; + } +} + +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_icmpv6(struct sk_buff *skb) +{ + unsigned int len = skb_transport_offset(skb) + sizeof(struct icmp6hdr); + unsigned int transport_len = ipv6_transport_len(skb); + struct sk_buff *skb_chk; + + if (!ipv6_mc_may_pull(skb, len)) + return -EINVAL; + + skb_chk = skb_checksum_trimmed(skb, transport_len, + ipv6_mc_validate_checksum); + if (!skb_chk) + return -EINVAL; + + if (skb_chk != skb) + kfree_skb(skb_chk); + + return 0; +} + +/** + * ipv6_mc_check_mld - checks whether this is a sane MLD packet + * @skb: the skb to validate + * + * Checks whether an IPv6 packet is a valid MLD packet. If so sets + * skb transport header 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 ICMPv6 packet + * with a hop-by-hop option. + * -ENODATA: IP+ICMPv6 header with hop-by-hop option validation succeeded + * but it is not an MLD packet. + * -ENOMEM: A memory allocation failure happened. + * + * Caller needs to set the skb network header and free any returned skb if it + * differs from the provided skb. + */ +int ipv6_mc_check_mld(struct sk_buff *skb) +{ + int ret; + + ret = ipv6_mc_check_ip6hdr(skb); + if (ret < 0) + return ret; + + ret = ipv6_mc_check_exthdrs(skb); + if (ret < 0) + return ret; + + ret = ipv6_mc_check_icmpv6(skb); + if (ret < 0) + return ret; + + return ipv6_mc_check_mld_msg(skb); +} +EXPORT_SYMBOL(ipv6_mc_check_mld); |