[B.A.T.M.A.N.] [PATCH net-next 0/4] bridge: implement Multicast Router Discovery (RFC4286)
Hi,
This patchset adds initial Multicast Router Discovery support to the Linux bridge (RFC4286). With MRD it is possible to detect multicast routers and mark bridge ports and forward multicast packets to such routers accordingly.
So far, multicast routers are detected via IGMP/MLD queries and PIM messages in the Linux bridge. As there is only one active, selected querier at a time RFC4541 ("Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches") section 2.1.1.a) recommends snooping Multicast Router Advertisements as provided by MRD (RFC4286).
The first two patches are refactoring some existing code which is reused for parsing the Multicast Router Advertisements later in the fourth patch. The third patch lets the bridge join the all-snoopers multicast address to be able to reliably receive the Multicast Router Advertisements.
What is not implemented yet from RFC4286 yet:
* Sending Multicast Router Solicitations: -> RFC4286: "[...] may be sent when [...] an interface is (re-)initialized [or] MRD is enabled" * Snooping Multicast Router Terminations: -> currently this only relies on our own timeouts * Adjusting timeouts with the values provided in the announcements
Regards, Linus
This patch refactors ip_mc_check_igmp(), ipv6_mc_check_mld() and their callers (more precisely, the Linux bridge) to not rely on the skb_trimmed parameter anymore.
An skb with its tail trimmed to the IP packet length was initially introduced for the following three reasons:
1) To be able to verify the ICMPv6 checksum. 2) To be able to distinguish the version of an IGMP or MLD query. They are distinguishable only by their size. 3) To avoid parsing data for an IGMPv3 or MLDv2 report that is beyond the IP packet but still within the skb.
The first case still uses a cloned and potentially trimmed skb to verfiy. However, there is no need to propagate it to the caller. For the second and third case explicit IP packet length checks were added.
This hopefully makes ip_mc_check_igmp() and ipv6_mc_check_mld() easier to read and verfiy, as well as easier to use.
Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue --- include/linux/igmp.h | 11 ++++++++- include/linux/ip.h | 5 ++++ include/linux/ipv6.h | 6 +++++ include/net/addrconf.h | 12 +++++++++- net/batman-adv/multicast.c | 4 ++-- net/bridge/br_multicast.c | 57 +++++++++++++++++++++++----------------------- net/ipv4/igmp.c | 23 ++++--------------- net/ipv6/mcast_snoop.c | 24 ++++--------------- 8 files changed, 70 insertions(+), 72 deletions(-)
diff --git a/include/linux/igmp.h b/include/linux/igmp.h index 119f53941c12..8b4348f69bc5 100644 --- a/include/linux/igmp.h +++ b/include/linux/igmp.h @@ -18,6 +18,7 @@ #include <linux/skbuff.h> #include <linux/timer.h> #include <linux/in.h> +#include <linux/ip.h> #include <linux/refcount.h> #include <uapi/linux/igmp.h>
@@ -106,6 +107,14 @@ struct ip_mc_list { #define IGMPV3_QQIC(value) IGMPV3_EXP(0x80, 4, 3, value) #define IGMPV3_MRC(value) IGMPV3_EXP(0x80, 4, 3, value)
+static inline int ip_mc_may_pull(struct sk_buff *skb, unsigned int len) +{ + if (skb_transport_offset(skb) + ip_transport_len(skb) < len) + return -EINVAL; + + return pskb_may_pull(skb, len); +} + extern int ip_check_mc_rcu(struct in_device *dev, __be32 mc_addr, __be32 src_addr, u8 proto); extern int igmp_rcv(struct sk_buff *); extern int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr); @@ -130,6 +139,6 @@ 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); +int ip_mc_check_igmp(struct sk_buff *skb);
#endif diff --git a/include/linux/ip.h b/include/linux/ip.h index 492bc6513533..482b7b7c9f30 100644 --- a/include/linux/ip.h +++ b/include/linux/ip.h @@ -34,4 +34,9 @@ static inline struct iphdr *ipip_hdr(const struct sk_buff *skb) { return (struct iphdr *)skb_transport_header(skb); } + +static inline unsigned int ip_transport_len(const struct sk_buff *skb) +{ + return ntohs(ip_hdr(skb)->tot_len) - skb_network_header_len(skb); +} #endif /* _LINUX_IP_H */ diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index 495e834c1367..6d45ce784bea 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -104,6 +104,12 @@ static inline struct ipv6hdr *ipipv6_hdr(const struct sk_buff *skb) return (struct ipv6hdr *)skb_transport_header(skb); }
+static inline unsigned int ipv6_transport_len(const struct sk_buff *skb) +{ + return ntohs(ipv6_hdr(skb)->payload_len) + sizeof(struct ipv6hdr) - + skb_network_header_len(skb); +} + /* This structure contains results of exthdrs parsing as offsets from skb->nh. diff --git a/include/net/addrconf.h b/include/net/addrconf.h index 1656c5978498..daf11dcb0f70 100644 --- a/include/net/addrconf.h +++ b/include/net/addrconf.h @@ -49,6 +49,7 @@ struct prefix_info { struct in6_addr prefix; };
+#include <linux/ipv6.h> #include <linux/netdevice.h> #include <net/if_inet6.h> #include <net/ipv6.h> @@ -201,6 +202,15 @@ u32 ipv6_addr_label(struct net *net, const struct in6_addr *addr, /* * multicast prototypes (mcast.c) */ +static inline int ipv6_mc_may_pull(struct sk_buff *skb, + unsigned int len) +{ + if (skb_transport_offset(skb) + ipv6_transport_len(skb) < len) + return -EINVAL; + + return pskb_may_pull(skb, len); +} + int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr); int ipv6_sock_mc_drop(struct sock *sk, int ifindex, @@ -219,7 +229,7 @@ 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); +int ipv6_mc_check_mld(struct sk_buff *skb); void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp);
bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group, diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c index 69244e4598f5..1dd70f048e7b 100644 --- a/net/batman-adv/multicast.c +++ b/net/batman-adv/multicast.c @@ -674,7 +674,7 @@ static void batadv_mcast_mla_update(struct work_struct *work) */ static bool batadv_mcast_is_report_ipv4(struct sk_buff *skb) { - if (ip_mc_check_igmp(skb, NULL) < 0) + if (ip_mc_check_igmp(skb) < 0) return false;
switch (igmp_hdr(skb)->type) { @@ -741,7 +741,7 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv, */ static bool batadv_mcast_is_report_ipv6(struct sk_buff *skb) { - if (ipv6_mc_check_mld(skb, NULL) < 0) + if (ipv6_mc_check_mld(skb) < 0) return false;
switch (icmp6_hdr(skb)->icmp6_type) { diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 3aeff0895669..156c4905639e 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -938,7 +938,7 @@ static int br_ip4_multicast_igmp3_report(struct net_bridge *br,
for (i = 0; i < num; i++) { len += sizeof(*grec); - if (!pskb_may_pull(skb, len)) + if (!ip_mc_may_pull(skb, len)) return -EINVAL;
grec = (void *)(skb->data + len - sizeof(*grec)); @@ -946,7 +946,7 @@ static int br_ip4_multicast_igmp3_report(struct net_bridge *br, type = grec->grec_type;
len += ntohs(grec->grec_nsrcs) * 4; - if (!pskb_may_pull(skb, len)) + if (!ip_mc_may_pull(skb, len)) return -EINVAL;
/* We treat this as an IGMPv2 report for now. */ @@ -985,15 +985,17 @@ static int br_ip6_multicast_mld2_report(struct net_bridge *br, struct sk_buff *skb, u16 vid) { + unsigned int nsrcs_offset; const unsigned char *src; struct icmp6hdr *icmp6h; struct mld2_grec *grec; + unsigned int grec_len; int i; int len; int num; int err = 0;
- if (!pskb_may_pull(skb, sizeof(*icmp6h))) + if (!ipv6_mc_may_pull(skb, sizeof(*icmp6h))) return -EINVAL;
icmp6h = icmp6_hdr(skb); @@ -1003,21 +1005,25 @@ static int br_ip6_multicast_mld2_report(struct net_bridge *br, for (i = 0; i < num; i++) { __be16 *nsrcs, _nsrcs;
- nsrcs = skb_header_pointer(skb, - len + offsetof(struct mld2_grec, - grec_nsrcs), + nsrcs_offset = len + offsetof(struct mld2_grec, grec_nsrcs); + + if (skb_transport_offset(skb) + ipv6_transport_len(skb) < + nsrcs_offset + sizeof(_nsrcs)) + return -EINVAL; + + nsrcs = skb_header_pointer(skb, nsrcs_offset, sizeof(_nsrcs), &_nsrcs); if (!nsrcs) return -EINVAL;
- if (!pskb_may_pull(skb, - len + sizeof(*grec) + - sizeof(struct in6_addr) * ntohs(*nsrcs))) + grec_len = sizeof(*grec) + + sizeof(struct in6_addr) * ntohs(*nsrcs); + + if (!ipv6_mc_may_pull(skb, len + grec_len)) return -EINVAL;
grec = (struct mld2_grec *)(skb->data + len); - len += sizeof(*grec) + - sizeof(struct in6_addr) * ntohs(*nsrcs); + len += grec_len;
/* We treat these as MLDv1 reports for now. */ switch (grec->grec_type) { @@ -1219,6 +1225,7 @@ static void br_ip4_multicast_query(struct net_bridge *br, struct sk_buff *skb, u16 vid) { + unsigned int transport_len = ip_transport_len(skb); const struct iphdr *iph = ip_hdr(skb); struct igmphdr *ih = igmp_hdr(skb); struct net_bridge_mdb_entry *mp; @@ -1228,7 +1235,6 @@ static void br_ip4_multicast_query(struct net_bridge *br, struct br_ip saddr; unsigned long max_delay; unsigned long now = jiffies; - unsigned int offset = skb_transport_offset(skb); __be32 group;
spin_lock(&br->multicast_lock); @@ -1238,14 +1244,14 @@ static void br_ip4_multicast_query(struct net_bridge *br,
group = ih->group;
- if (skb->len == offset + sizeof(*ih)) { + if (transport_len == sizeof(*ih)) { max_delay = ih->code * (HZ / IGMP_TIMER_SCALE);
if (!max_delay) { max_delay = 10 * HZ; group = 0; } - } else if (skb->len >= offset + sizeof(*ih3)) { + } else if (transport_len >= sizeof(*ih3)) { ih3 = igmpv3_query_hdr(skb); if (ih3->nsrcs) goto out; @@ -1296,6 +1302,7 @@ static int br_ip6_multicast_query(struct net_bridge *br, struct sk_buff *skb, u16 vid) { + unsigned int transport_len = ipv6_transport_len(skb); const struct ipv6hdr *ip6h = ipv6_hdr(skb); struct mld_msg *mld; struct net_bridge_mdb_entry *mp; @@ -1315,7 +1322,7 @@ static int br_ip6_multicast_query(struct net_bridge *br, (port && port->state == BR_STATE_DISABLED)) goto out;
- if (skb->len == offset + sizeof(*mld)) { + if (transport_len == sizeof(*mld)) { if (!pskb_may_pull(skb, offset + sizeof(*mld))) { err = -EINVAL; goto out; @@ -1581,12 +1588,11 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br, struct sk_buff *skb, u16 vid) { - struct sk_buff *skb_trimmed = NULL; const unsigned char *src; struct igmphdr *ih; int err;
- err = ip_mc_check_igmp(skb, &skb_trimmed); + err = ip_mc_check_igmp(skb);
if (err == -ENOMSG) { if (!ipv4_is_local_multicast(ip_hdr(skb)->daddr)) { @@ -1612,19 +1618,16 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br, err = br_ip4_multicast_add_group(br, port, ih->group, vid, src); break; case IGMPV3_HOST_MEMBERSHIP_REPORT: - err = br_ip4_multicast_igmp3_report(br, port, skb_trimmed, vid); + err = br_ip4_multicast_igmp3_report(br, port, skb, vid); break; case IGMP_HOST_MEMBERSHIP_QUERY: - br_ip4_multicast_query(br, port, skb_trimmed, vid); + br_ip4_multicast_query(br, port, skb, vid); break; case IGMP_HOST_LEAVE_MESSAGE: br_ip4_multicast_leave_group(br, port, ih->group, vid, src); break; }
- if (skb_trimmed && skb_trimmed != skb) - kfree_skb(skb_trimmed); - br_multicast_count(br, port, skb, BR_INPUT_SKB_CB(skb)->igmp, BR_MCAST_DIR_RX);
@@ -1637,12 +1640,11 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br, struct sk_buff *skb, u16 vid) { - struct sk_buff *skb_trimmed = NULL; const unsigned char *src; struct mld_msg *mld; int err;
- err = ipv6_mc_check_mld(skb, &skb_trimmed); + err = ipv6_mc_check_mld(skb);
if (err == -ENOMSG) { if (!ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr)) @@ -1664,10 +1666,10 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br, src); break; case ICMPV6_MLD2_REPORT: - err = br_ip6_multicast_mld2_report(br, port, skb_trimmed, vid); + err = br_ip6_multicast_mld2_report(br, port, skb, vid); break; case ICMPV6_MGM_QUERY: - err = br_ip6_multicast_query(br, port, skb_trimmed, vid); + err = br_ip6_multicast_query(br, port, skb, vid); break; case ICMPV6_MGM_REDUCTION: src = eth_hdr(skb)->h_source; @@ -1675,9 +1677,6 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br, break; }
- if (skb_trimmed && skb_trimmed != skb) - kfree_skb(skb_trimmed); - br_multicast_count(br, port, skb, BR_INPUT_SKB_CB(skb)->igmp, BR_MCAST_DIR_RX);
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 765b2b32c4a4..b1f6d93282d7 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -1544,7 +1544,7 @@ 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) +static int __ip_mc_check_igmp(struct sk_buff *skb)
{ struct sk_buff *skb_chk; @@ -1566,16 +1566,10 @@ static int __ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed) if (ret) goto err;
- if (skb_trimmed) - *skb_trimmed = skb_chk; - /* free now unneeded clone */ - else if (skb_chk != skb) - kfree_skb(skb_chk); - ret = 0;
err: - if (ret && skb_chk && skb_chk != skb) + if (skb_chk && skb_chk != skb) kfree_skb(skb_chk);
return ret; @@ -1584,7 +1578,6 @@ static int __ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed) /** * 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 transport header accordingly and returns zero. @@ -1594,18 +1587,10 @@ static int __ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed) * -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). - * * Caller needs to set the skb network header and free any returned skb if it * differs from the provided skb. */ -int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed) +int ip_mc_check_igmp(struct sk_buff *skb) { int ret = ip_mc_check_iphdr(skb);
@@ -1615,7 +1600,7 @@ int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed) if (ip_hdr(skb)->protocol != IPPROTO_IGMP) return -ENOMSG;
- return __ip_mc_check_igmp(skb, skb_trimmed); + return __ip_mc_check_igmp(skb); } EXPORT_SYMBOL(ip_mc_check_igmp);
diff --git a/net/ipv6/mcast_snoop.c b/net/ipv6/mcast_snoop.c index 9405b04eecc6..1a917dc80d5e 100644 --- a/net/ipv6/mcast_snoop.c +++ b/net/ipv6/mcast_snoop.c @@ -136,8 +136,7 @@ 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) +static int __ipv6_mc_check_mld(struct sk_buff *skb)
{ struct sk_buff *skb_chk = NULL; @@ -160,16 +159,10 @@ static int __ipv6_mc_check_mld(struct sk_buff *skb, if (ret) goto err;
- if (skb_trimmed) - *skb_trimmed = skb_chk; - /* free now unneeded clone */ - else if (skb_chk != skb) - kfree_skb(skb_chk); - ret = 0;
err: - if (ret && skb_chk && skb_chk != skb) + if (skb_chk && skb_chk != skb) kfree_skb(skb_chk);
return ret; @@ -178,7 +171,6 @@ static int __ipv6_mc_check_mld(struct sk_buff *skb, /** * 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 transport header accordingly and returns zero. @@ -188,18 +180,10 @@ static int __ipv6_mc_check_mld(struct sk_buff *skb, * -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). - * * 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, struct sk_buff **skb_trimmed) +int ipv6_mc_check_mld(struct sk_buff *skb) { int ret;
@@ -211,6 +195,6 @@ int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed) if (ret < 0) return ret;
- return __ipv6_mc_check_mld(skb, skb_trimmed); + return __ipv6_mc_check_mld(skb); } EXPORT_SYMBOL(ipv6_mc_check_mld);
With this patch the internal use of the skb_trimmed is reduced to the ICMPv6/IGMP checksum verification. And for the length checks the newly introduced helper functions are used instead of calculating and checking with skb->len directly.
These changes should hopefully make it easier to verify that length checks are performed properly.
Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue --- net/ipv4/igmp.c | 51 ++++++++++++++++++----------------------- net/ipv6/mcast_snoop.c | 62 ++++++++++++++++++++++++-------------------------- 2 files changed, 52 insertions(+), 61 deletions(-)
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index b1f6d93282d7..a40e48ded10d 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -1493,22 +1493,22 @@ static int ip_mc_check_igmp_reportv3(struct sk_buff *skb)
len += sizeof(struct igmpv3_report);
- return pskb_may_pull(skb, len) ? 0 : -EINVAL; + return ip_mc_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; + unsigned int transport_len = ip_transport_len(skb); + unsigned int len;
/* IGMPv{1,2}? */ - if (skb->len != len) { + if (transport_len != sizeof(struct igmphdr)) { /* or IGMPv3? */ - len += sizeof(struct igmpv3_query) - sizeof(struct igmphdr); - if (skb->len < len || !pskb_may_pull(skb, len)) + if (transport_len < sizeof(struct igmpv3_query)) + return -EINVAL; + + len = skb_transport_offset(skb) + sizeof(struct igmpv3_query); + if (!ip_mc_may_pull(skb, len)) return -EINVAL; }
@@ -1544,35 +1544,24 @@ 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) - +static int ip_mc_check_igmp_csum(struct sk_buff *skb) { - struct sk_buff *skb_chk; - unsigned int transport_len; unsigned int len = skb_transport_offset(skb) + sizeof(struct igmphdr); - int ret = -EINVAL; + unsigned int transport_len = ip_transport_len(skb); + struct sk_buff *skb_chk;
- transport_len = ntohs(ip_hdr(skb)->tot_len) - ip_hdrlen(skb); + if (!ip_mc_may_pull(skb, len)) + return -EINVAL;
skb_chk = skb_checksum_trimmed(skb, transport_len, ip_mc_validate_checksum); if (!skb_chk) - goto err; + return -EINVAL;
- if (!pskb_may_pull(skb_chk, len)) - goto err; - - ret = ip_mc_check_igmp_msg(skb_chk); - if (ret) - goto err; - - ret = 0; - -err: - if (skb_chk && skb_chk != skb) + if (skb_chk != skb) kfree_skb(skb_chk);
- return ret; + return 0; }
/** @@ -1600,7 +1589,11 @@ int ip_mc_check_igmp(struct sk_buff *skb) if (ip_hdr(skb)->protocol != IPPROTO_IGMP) return -ENOMSG;
- return __ip_mc_check_igmp(skb); + ret = ip_mc_check_igmp_csum(skb); + if (ret < 0) + return ret; + + return ip_mc_check_igmp_msg(skb); } EXPORT_SYMBOL(ip_mc_check_igmp);
diff --git a/net/ipv6/mcast_snoop.c b/net/ipv6/mcast_snoop.c index 1a917dc80d5e..a72ddfc40eb3 100644 --- a/net/ipv6/mcast_snoop.c +++ b/net/ipv6/mcast_snoop.c @@ -77,27 +77,27 @@ static int ipv6_mc_check_mld_reportv2(struct sk_buff *skb)
len += sizeof(struct mld2_report);
- return pskb_may_pull(skb, len) ? 0 : -EINVAL; + 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 = skb_transport_offset(skb); + 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;
- len += sizeof(struct mld_msg); - if (skb->len < len) - return -EINVAL; - /* MLDv1? */ - if (skb->len != len) { + if (transport_len != sizeof(struct mld_msg)) { /* or MLDv2? */ - len += sizeof(struct mld2_query) - sizeof(struct mld_msg); - if (skb->len < len || !pskb_may_pull(skb, len)) + 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; }
@@ -115,7 +115,13 @@ static int ipv6_mc_check_mld_query(struct sk_buff *skb)
static int ipv6_mc_check_mld_msg(struct sk_buff *skb) { - struct mld_msg *mld = (struct mld_msg *)skb_transport_header(skb); + unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg); + struct mld_msg *mld; + + if (!ipv6_mc_may_pull(skb, len)) + return -EINVAL; + + mld = (struct mld_msg *)skb_transport_header(skb);
switch (mld->mld_type) { case ICMPV6_MGM_REDUCTION: @@ -136,36 +142,24 @@ 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) - +static int ipv6_mc_check_icmpv6(struct sk_buff *skb) { - struct sk_buff *skb_chk = NULL; - unsigned int transport_len; - unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg); - int ret = -EINVAL; + unsigned int len = skb_transport_offset(skb) + sizeof(struct icmp6hdr); + unsigned int transport_len = ipv6_transport_len(skb); + struct sk_buff *skb_chk;
- transport_len = ntohs(ipv6_hdr(skb)->payload_len); - transport_len -= skb_transport_offset(skb) - sizeof(struct ipv6hdr); + if (!ipv6_mc_may_pull(skb, len)) + return -EINVAL;
skb_chk = skb_checksum_trimmed(skb, transport_len, ipv6_mc_validate_checksum); if (!skb_chk) - goto err; + return -EINVAL;
- if (!pskb_may_pull(skb_chk, len)) - goto err; - - ret = ipv6_mc_check_mld_msg(skb_chk); - if (ret) - goto err; - - ret = 0; - -err: - if (skb_chk && skb_chk != skb) + if (skb_chk != skb) kfree_skb(skb_chk);
- return ret; + return 0; }
/** @@ -195,6 +189,10 @@ int ipv6_mc_check_mld(struct sk_buff *skb) if (ret < 0) return ret;
- return __ipv6_mc_check_mld(skb); + ret = ipv6_mc_check_icmpv6(skb); + if (ret < 0) + return ret; + + return ipv6_mc_check_mld_msg(skb); } EXPORT_SYMBOL(ipv6_mc_check_mld);
Next to snooping IGMP/MLD queries RFC4541, section 2.1.1.a) recommends to snoop multicast router advertisements to detect multicast routers.
Multicast router advertisements are sent to an "all-snoopers" multicast address. To be able to receive them reliably, we need to join this group.
Otherwise other snooping switches might refrain from forwarding these advertisements to us.
Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue --- include/uapi/linux/in.h | 9 +++--- net/bridge/br_multicast.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++- net/ipv6/mcast.c | 2 ++ 3 files changed, 78 insertions(+), 5 deletions(-)
diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h index f6052e70bf40..7ab685cacb8f 100644 --- a/include/uapi/linux/in.h +++ b/include/uapi/linux/in.h @@ -292,10 +292,11 @@ struct sockaddr_in { #define IN_LOOPBACK(a) ((((long int) (a)) & 0xff000000) == 0x7f000000)
/* Defines for Multicast INADDR */ -#define INADDR_UNSPEC_GROUP 0xe0000000U /* 224.0.0.0 */ -#define INADDR_ALLHOSTS_GROUP 0xe0000001U /* 224.0.0.1 */ -#define INADDR_ALLRTRS_GROUP 0xe0000002U /* 224.0.0.2 */ -#define INADDR_MAX_LOCAL_GROUP 0xe00000ffU /* 224.0.0.255 */ +#define INADDR_UNSPEC_GROUP 0xe0000000U /* 224.0.0.0 */ +#define INADDR_ALLHOSTS_GROUP 0xe0000001U /* 224.0.0.1 */ +#define INADDR_ALLRTRS_GROUP 0xe0000002U /* 224.0.0.2 */ +#define INADDR_ALLSNOOPERS_GROUP 0xe000006aU /* 224.0.0.106 */ +#define INADDR_MAX_LOCAL_GROUP 0xe00000ffU /* 224.0.0.255 */ #endif
/* <asm/byteorder.h> contains the htonl type stuff.. */ diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 156c4905639e..2366f4a2780e 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1780,6 +1780,68 @@ void br_multicast_init(struct net_bridge *br) INIT_HLIST_HEAD(&br->mdb_list); }
+static void br_ip4_multicast_join_snoopers(struct net_bridge *br) +{ + struct in_device *in_dev = in_dev_get(br->dev); + + if (!in_dev) + return; + + ip_mc_inc_group(in_dev, htonl(INADDR_ALLSNOOPERS_GROUP)); + in_dev_put(in_dev); +} + +#if IS_ENABLED(CONFIG_IPV6) +static void br_ip6_multicast_join_snoopers(struct net_bridge *br) +{ + struct in6_addr addr; + + ipv6_addr_set(&addr, htonl(0xff020000), 0, 0, htonl(0x6a)); + ipv6_dev_mc_inc(br->dev, &addr); +} +#else +static inline void br_ip6_multicast_join_snoopers(struct net_bridge *br) +{ +} +#endif + +static void br_multicast_join_snoopers(struct net_bridge *br) +{ + br_ip4_multicast_join_snoopers(br); + br_ip6_multicast_join_snoopers(br); +} + +static void br_ip4_multicast_leave_snoopers(struct net_bridge *br) +{ + struct in_device *in_dev = in_dev_get(br->dev); + + if (WARN_ON(!in_dev)) + return; + + ip_mc_dec_group(in_dev, htonl(INADDR_ALLSNOOPERS_GROUP)); + in_dev_put(in_dev); +} + +#if IS_ENABLED(CONFIG_IPV6) +static void br_ip6_multicast_leave_snoopers(struct net_bridge *br) +{ + struct in6_addr addr; + + ipv6_addr_set(&addr, htonl(0xff020000), 0, 0, htonl(0x6a)); + ipv6_dev_mc_dec(br->dev, &addr); +} +#else +static inline void br_ip6_multicast_leave_snoopers(struct net_bridge *br) +{ +} +#endif + +static void br_multicast_leave_snoopers(struct net_bridge *br) +{ + br_ip4_multicast_leave_snoopers(br); + br_ip6_multicast_leave_snoopers(br); +} + static void __br_multicast_open(struct net_bridge *br, struct bridge_mcast_own_query *query) { @@ -1793,6 +1855,9 @@ static void __br_multicast_open(struct net_bridge *br,
void br_multicast_open(struct net_bridge *br) { + if (br_opt_get(br, BROPT_MULTICAST_ENABLED)) + br_multicast_join_snoopers(br); + __br_multicast_open(br, &br->ip4_own_query); #if IS_ENABLED(CONFIG_IPV6) __br_multicast_open(br, &br->ip6_own_query); @@ -1808,6 +1873,9 @@ void br_multicast_stop(struct net_bridge *br) del_timer_sync(&br->ip6_other_query.timer); del_timer_sync(&br->ip6_own_query.timer); #endif + + if (br_opt_get(br, BROPT_MULTICAST_ENABLED)) + br_multicast_leave_snoopers(br); }
void br_multicast_dev_del(struct net_bridge *br) @@ -1943,8 +2011,10 @@ int br_multicast_toggle(struct net_bridge *br, unsigned long val)
br_mc_disabled_update(br->dev, val); br_opt_toggle(br, BROPT_MULTICAST_ENABLED, !!val); - if (!br_opt_get(br, BROPT_MULTICAST_ENABLED)) + if (!br_opt_get(br, BROPT_MULTICAST_ENABLED)) { + br_multicast_leave_snoopers(br); goto unlock; + }
if (!netif_running(br->dev)) goto unlock; diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 21f6deb2aec9..42f3f5cd349f 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -940,6 +940,7 @@ int ipv6_dev_mc_inc(struct net_device *dev, const struct in6_addr *addr) { return __ipv6_dev_mc_inc(dev, addr, MCAST_EXCLUDE); } +EXPORT_SYMBOL(ipv6_dev_mc_inc);
/* * device multicast group del @@ -987,6 +988,7 @@ int ipv6_dev_mc_dec(struct net_device *dev, const struct in6_addr *addr)
return err; } +EXPORT_SYMBOL(ipv6_dev_mc_dec);
/* * check if the interface/address pair is valid
When multiple multicast routers are present in a broadcast domain then only one of them will be detectable via IGMP/MLD query snooping. The multicast router with the lowest IP address will become the selected and active querier while all other multicast routers will then refrain from sending queries.
To detect such rather silent multicast routers, too, RFC4286 ("Multicast Router Discovery") provides a standardized protocol to detect multicast routers for multicast snooping switches.
This patch implements the necessary MRD Advertisement message parsing and after successful processing adds such routers to the internal multicast router list.
Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue --- include/linux/in.h | 5 +++++ include/net/addrconf.h | 15 +++++++++++++ include/uapi/linux/icmpv6.h | 2 ++ include/uapi/linux/igmp.h | 1 + net/bridge/br_multicast.c | 55 +++++++++++++++++++++++++++++++++++++++++++++ net/ipv6/mcast_snoop.c | 5 ++++- 6 files changed, 82 insertions(+), 1 deletion(-)
diff --git a/include/linux/in.h b/include/linux/in.h index 31b493734763..435e7f2a513a 100644 --- a/include/linux/in.h +++ b/include/linux/in.h @@ -60,6 +60,11 @@ static inline bool ipv4_is_lbcast(__be32 addr) return addr == htonl(INADDR_BROADCAST); }
+static inline bool ipv4_is_all_snoopers(__be32 addr) +{ + return addr == htonl(INADDR_ALLSNOOPERS_GROUP); +} + static inline bool ipv4_is_zeronet(__be32 addr) { return (addr & htonl(0xff000000)) == htonl(0x00000000); diff --git a/include/net/addrconf.h b/include/net/addrconf.h index daf11dcb0f70..20d523ee2fec 100644 --- a/include/net/addrconf.h +++ b/include/net/addrconf.h @@ -229,6 +229,7 @@ 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_icmpv6(struct sk_buff *skb); int ipv6_mc_check_mld(struct sk_buff *skb); void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp);
@@ -499,6 +500,20 @@ static inline bool ipv6_addr_is_solict_mult(const struct in6_addr *addr) #endif }
+static inline bool ipv6_addr_is_all_snoopers(const struct in6_addr *addr) +{ +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 + __be64 *p = (__be64 *)addr; + + return ((p[0] ^ cpu_to_be64(0xff02000000000000UL)) | + (p[1] ^ cpu_to_be64(0x6a))) == 0UL; +#else + return ((addr->s6_addr32[0] ^ htonl(0xff020000)) | + addr->s6_addr32[1] | addr->s6_addr32[2] | + (addr->s6_addr32[3] ^ htonl(0x0000006a))) == 0; +#endif +} + #ifdef CONFIG_PROC_FS int if6_proc_init(void); void if6_proc_exit(void); diff --git a/include/uapi/linux/icmpv6.h b/include/uapi/linux/icmpv6.h index caf8dc019250..325395f56bfa 100644 --- a/include/uapi/linux/icmpv6.h +++ b/include/uapi/linux/icmpv6.h @@ -108,6 +108,8 @@ struct icmp6hdr { #define ICMPV6_MOBILE_PREFIX_SOL 146 #define ICMPV6_MOBILE_PREFIX_ADV 147
+#define ICMPV6_MRDISC_ADV 151 + /* * Codes for Destination Unreachable */ diff --git a/include/uapi/linux/igmp.h b/include/uapi/linux/igmp.h index 7e44ac02ca18..90c28bc466c6 100644 --- a/include/uapi/linux/igmp.h +++ b/include/uapi/linux/igmp.h @@ -93,6 +93,7 @@ struct igmpv3_query { #define IGMP_MTRACE_RESP 0x1e #define IGMP_MTRACE 0x1f
+#define IGMP_MRDISC_ADV 0x30 /* From RFC4286 */
/* * Use the BSD names for these for compatibility diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 2366f4a2780e..2c46c7aca571 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -14,6 +14,7 @@ #include <linux/export.h> #include <linux/if_ether.h> #include <linux/igmp.h> +#include <linux/in.h> #include <linux/jhash.h> #include <linux/kernel.h> #include <linux/log2.h> @@ -29,10 +30,12 @@ #include <net/ip.h> #include <net/switchdev.h> #if IS_ENABLED(CONFIG_IPV6) +#include <linux/icmpv6.h> #include <net/ipv6.h> #include <net/mld.h> #include <net/ip6_checksum.h> #include <net/addrconf.h> +#include <net/ipv6.h> #endif
#include "br_private.h" @@ -1583,6 +1586,19 @@ static void br_multicast_pim(struct net_bridge *br, br_multicast_mark_router(br, port); }
+static int br_ip4_multicast_mrd_rcv(struct net_bridge *br, + struct net_bridge_port *port, + struct sk_buff *skb) +{ + if (ip_hdr(skb)->protocol != IPPROTO_IGMP || + igmp_hdr(skb)->type != IGMP_MRDISC_ADV) + return -ENOMSG; + + br_multicast_mark_router(br, port); + + return 0; +} + static int br_multicast_ipv4_rcv(struct net_bridge *br, struct net_bridge_port *port, struct sk_buff *skb, @@ -1600,7 +1616,15 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br, } else if (pim_ipv4_all_pim_routers(ip_hdr(skb)->daddr)) { if (ip_hdr(skb)->protocol == IPPROTO_PIM) br_multicast_pim(br, port, skb); + } else if (ipv4_is_all_snoopers(ip_hdr(skb)->daddr)) { + err = br_ip4_multicast_mrd_rcv(br, port, skb); + + if (err < 0 && err != -ENOMSG) { + br_multicast_err_count(br, port, skb->protocol); + return err; + } } + return 0; } else if (err < 0) { br_multicast_err_count(br, port, skb->protocol); @@ -1635,6 +1659,27 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br, }
#if IS_ENABLED(CONFIG_IPV6) +static int br_ip6_multicast_mrd_rcv(struct net_bridge *br, + struct net_bridge_port *port, + struct sk_buff *skb) +{ + int ret; + + if (ipv6_hdr(skb)->nexthdr != IPPROTO_ICMPV6) + return -ENOMSG; + + ret = ipv6_mc_check_icmpv6(skb); + if (ret < 0) + return ret; + + if (icmp6_hdr(skb)->icmp6_type != ICMPV6_MRDISC_ADV) + return -ENOMSG; + + br_multicast_mark_router(br, port); + + return 0; +} + static int br_multicast_ipv6_rcv(struct net_bridge *br, struct net_bridge_port *port, struct sk_buff *skb, @@ -1649,6 +1694,16 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br, if (err == -ENOMSG) { if (!ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr)) BR_INPUT_SKB_CB(skb)->mrouters_only = 1; + + if (ipv6_addr_is_all_snoopers(&ipv6_hdr(skb)->daddr)) { + err = br_ip6_multicast_mrd_rcv(br, port, skb); + + if (err < 0 && err != -ENOMSG) { + br_multicast_err_count(br, port, skb->protocol); + return err; + } + } + return 0; } else if (err < 0) { br_multicast_err_count(br, port, skb->protocol); diff --git a/net/ipv6/mcast_snoop.c b/net/ipv6/mcast_snoop.c index a72ddfc40eb3..55e2ac179f28 100644 --- a/net/ipv6/mcast_snoop.c +++ b/net/ipv6/mcast_snoop.c @@ -41,6 +41,8 @@ static int ipv6_mc_check_ip6hdr(struct sk_buff *skb) if (skb->len < len || len <= offset) return -EINVAL;
+ skb_set_transport_header(skb, offset); + return 0; }
@@ -142,7 +144,7 @@ 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) +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); @@ -161,6 +163,7 @@ static int ipv6_mc_check_icmpv6(struct sk_buff *skb)
return 0; } +EXPORT_SYMBOL(ipv6_mc_check_icmpv6);
/** * ipv6_mc_check_mld - checks whether this is a sane MLD packet
On 12/21/18 5:15 PM, Linus Lüssing wrote:
Hi,
This patchset adds initial Multicast Router Discovery support to the Linux bridge (RFC4286). With MRD it is possible to detect multicast routers and mark bridge ports and forward multicast packets to such routers accordingly.
So far, multicast routers are detected via IGMP/MLD queries and PIM messages in the Linux bridge. As there is only one active, selected querier at a time RFC4541 ("Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches") section 2.1.1.a) recommends snooping Multicast Router Advertisements as provided by MRD (RFC4286).
The first two patches are refactoring some existing code which is reused for parsing the Multicast Router Advertisements later in the fourth patch. The third patch lets the bridge join the all-snoopers multicast address to be able to reliably receive the Multicast Router Advertisements.
What is not implemented yet from RFC4286 yet:
- Sending Multicast Router Solicitations: -> RFC4286: "[...] may be sent when [...] an interface is (re-)initialized [or] MRD is enabled"
- Snooping Multicast Router Terminations: -> currently this only relies on our own timeouts
- Adjusting timeouts with the values provided in the announcements
Regards, Linus
Hi Linus, Nice work, unfortunately net-next is currenty closed. Anyway I'll review the patches in detail after the holidays so if there's anything it can be adjusted for when net-next opens up.
Thanks, Nik
From: Linus Lüssing linus.luessing@c0d3.blue Date: Fri, 21 Dec 2018 16:15:07 +0100
This patchset adds initial Multicast Router Discovery support to the Linux bridge (RFC4286). With MRD it is possible to detect multicast routers and mark bridge ports and forward multicast packets to such routers accordingly.
...
The net-next tree is currently closed, please resubmit this when it opens back up again.
Thank you.
b.a.t.m.a.n@lists.open-mesh.org
-
David Miller -
Linus Lüssing -
Nikolay Aleksandrov