diff options
| -rw-r--r-- | include/linux/igmp.h | 1 | ||||
| -rw-r--r-- | include/linux/skbuff.h | 3 | ||||
| -rw-r--r-- | include/net/addrconf.h | 1 | ||||
| -rw-r--r-- | net/bridge/br_multicast.c | 218 | ||||
| -rw-r--r-- | net/core/skbuff.c | 87 | ||||
| -rw-r--r-- | net/ipv4/igmp.c | 162 | ||||
| -rw-r--r-- | net/ipv6/Makefile | 1 | ||||
| -rw-r--r-- | net/ipv6/mcast_snoop.c | 213 |
8 files changed, 498 insertions, 188 deletions
diff --git a/include/linux/igmp.h b/include/linux/igmp.h index 2c677afeea47..193ad488d3e2 100644 --- a/include/linux/igmp.h +++ b/include/linux/igmp.h @@ -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 diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index acb83e249e3f..9c2f793573fa 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3419,6 +3419,9 @@ 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); +struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb, + unsigned int transport_len, + __sum16(*skb_chkf)(struct sk_buff *skb)); u32 skb_get_poff(const struct sk_buff *skb); u32 __skb_get_poff(const struct sk_buff *skb, void *data, diff --git a/include/net/addrconf.h b/include/net/addrconf.h index 80456f72d70a..def59d3a34d5 100644 --- a/include/net/addrconf.h +++ b/include/net/addrconf.h @@ -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, diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index b52f4cb8aee9..2d69d5cab52f 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -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) + 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) + kfree_skb(skb_trimmed); + return err; } #endif diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 3cfff2a3d651..1e4278a4dd7e 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4030,6 +4030,93 @@ int skb_checksum_setup(struct sk_buff *skb, bool recalculate) } EXPORT_SYMBOL(skb_checksum_setup); +/** + * skb_checksum_maybe_trim - maybe trims the given skb + * @skb: the skb to check + * @transport_len: the data length beyond the network header + * + * Checks whether the given skb has data beyond the given transport length. + * If so, returns a cloned skb trimmed to this transport length. + * Otherwise returns the provided skb. Returns NULL in error cases + * (e.g. transport_len exceeds skb length or out-of-memory). + * + * Caller needs to set the skb transport header and release the returned skb. + * Provided skb is consumed. + */ +static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb, + unsigned int transport_len) +{ + struct sk_buff *skb_chk; + unsigned int len = skb_transport_offset(skb) + transport_len; + int ret; + + if (skb->len < len) { + kfree_skb(skb); + return NULL; + } else if (skb->len == len) { + return skb; + } + + skb_chk = skb_clone(skb, GFP_ATOMIC); + kfree_skb(skb); + + if (!skb_chk) + return NULL; + + ret = pskb_trim_rcsum(skb_chk, len); + if (ret) { + kfree_skb(skb_chk); + return NULL; + } + + return skb_chk; +} + +/** + * skb_checksum_trimmed - validate checksum of an skb + * @skb: the skb to check + * @transport_len: the data length beyond the network header + * @skb_chkf: checksum function to use + * + * Applies the given checksum function skb_chkf to the provided skb. + * Returns a checked and maybe trimmed skb. Returns NULL on error. + * + * If the skb has data beyond the given transport length, then a + * trimmed & cloned skb is checked and returned. + * + * Caller needs to set the skb transport header and release the returned skb. + * Provided skb is consumed. + */ +struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb, + unsigned int transport_len, + __sum16(*skb_chkf)(struct sk_buff *skb)) +{ + struct sk_buff *skb_chk; + unsigned int offset = skb_transport_offset(skb); + int ret; + + skb_chk = skb_checksum_maybe_trim(skb, transport_len); + if (!skb_chk) + return NULL; + + if (!pskb_may_pull(skb_chk, offset)) { + kfree_skb(skb_chk); + return NULL; + } + + __skb_pull(skb_chk, offset); + ret = skb_chkf(skb_chk); + __skb_push(skb_chk, offset); + + if (ret) { + kfree_skb(skb_chk); + return NULL; + } + + return skb_chk; +} +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", 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. */ diff --git a/net/ipv6/Makefile b/net/ipv6/Makefile index 2e8c06108ab9..0f3f1999719a 100644 --- a/net/ipv6/Makefile +++ b/net/ipv6/Makefile @@ -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 diff --git a/net/ipv6/mcast_snoop.c b/net/ipv6/mcast_snoop.c new file mode 100644 index 000000000000..1a2cbc13a7d3 --- /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; + 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; + + 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); |