RTM_GETMULTICAST dumps IPv4 and IPv6 multicast group memberships, but
the device multicast list (dev->mc) is only available through
/proc/net/dev_mcast, so "ip maddr show" still has to parse procfs for
its link-layer entries.
Handle RTM_GETMULTICAST dumps with ifa_family set to AF_PACKET and
report every entry of dev->mc in the existing ifaddrmsg format:
- IFA_MULTICAST carries the raw link-layer address
- IFA_MC_USERS carries the entry reference count
- IFA_F_GLOBAL in IFA_FLAGS reports netdev_hw_addr::global_use, set
by dev_mc_add_global() (SIOCADDMULTI) and dev_mc_add_excl()
("bridge fdb add ... self"), i.e. entries added explicitly rather
than by a protocol join. This is the static column of
/proc/net/dev_mcast
- ifa_scope is RT_SCOPE_LINK
This covers every column of /proc/net/dev_mcast. AF_PACKET is the
family iproute2 already uses for link-layer addresses ("ip -0"), and
AF_UNSPEC keeps its "all families" meaning from RTM_GETADDR.
The default FDB dump also walks dev->mc, but only for Ethernet devices
without an ndo_fdb_dump of their own, so bridge, vxlan or macvlan
devices never show their multicast filter there, and it has no users
count or global_use bit. Extending it would change "bridge fdb show"
output and add NDA_* attributes.
There are no legacy users of AF_PACKET requests, so they are always
validated: prefixlen, flags and scope must be zero and a non-zero
ifa_index restricts the dump to that device. IFA_TARGET_NETNSID selects
another netns like the IPv4 and IPv6 dumps and is the only attribute
accepted. The dump runs under RCU and netif_addr_lock_bh() and does not
need RTNL.
Signed-off-by: Yuyang Huang <[email protected]>
---
include/uapi/linux/if_addr.h | 1 +
net/core/rtnetlink.c | 165 +++++++++++++++++++++++++++++++++++
2 files changed, 166 insertions(+)
diff --git a/include/uapi/linux/if_addr.h b/include/uapi/linux/if_addr.h
index 7fb630b7fe31..0a1ad9ebb47b 100644
--- a/include/uapi/linux/if_addr.h
+++ b/include/uapi/linux/if_addr.h
@@ -57,6 +57,7 @@ enum {
#define IFA_F_NOPREFIXROUTE 0x200
#define IFA_F_MCAUTOJOIN 0x400
#define IFA_F_STABLE_PRIVACY 0x800
+#define IFA_F_GLOBAL 0x1000
struct ifa_cacheinfo {
__u32 ifa_prefered;
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 81c5a6104dea..f54e9cb3bf30 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -4566,6 +4566,169 @@ static int rtnl_dump_all(struct sk_buff *skb, struct
netlink_callback *cb)
return skb->len ? : ret;
}
+static int rtnl_fill_mcaddr(struct sk_buff *skb, const struct net_device *dev,
+ const struct netdev_hw_addr *ha, u32 portid,
+ u32 seq, unsigned int flags, int netnsid)
+{
+ u32 ifa_flags = ha->global_use ? IFA_F_GLOBAL : 0;
+ struct ifaddrmsg *ifm;
+ struct nlmsghdr *nlh;
+
+ nlh = nlmsg_put(skb, portid, seq, RTM_GETMULTICAST, sizeof(*ifm),
+ flags);
+ if (!nlh)
+ return -EMSGSIZE;
+
+ ifm = nlmsg_data(nlh);
+ ifm->ifa_family = AF_PACKET;
+ ifm->ifa_prefixlen = 0;
+ /* ifm->ifa_flags holds 8 bits, the full value is in IFA_FLAGS */
+ ifm->ifa_flags = (__u8)ifa_flags;
+ ifm->ifa_scope = RT_SCOPE_LINK;
+ ifm->ifa_index = dev->ifindex;
+
+ if ((netnsid >= 0 &&
+ nla_put_s32(skb, IFA_TARGET_NETNSID, netnsid)) ||
+ nla_put(skb, IFA_MULTICAST, dev->addr_len, ha->addr) ||
+ nla_put_u32(skb, IFA_MC_USERS, ha->refcount) ||
+ nla_put_u32(skb, IFA_FLAGS, ifa_flags)) {
+ nlmsg_cancel(skb, nlh);
+ return -EMSGSIZE;
+ }
+
+ nlmsg_end(skb, nlh);
+ return 0;
+}
+
+static int rtnl_dump_mcaddr_dev(struct net_device *dev, struct sk_buff *skb,
+ struct netlink_callback *cb, int *s_addr_idx,
+ unsigned int flags, int netnsid)
+{
+ struct netdev_hw_addr *ha;
+ int addr_idx = 0;
+ int err = 0;
+
+ netif_addr_lock_bh(dev);
+ netdev_for_each_mc_addr(ha, dev) {
+ if (addr_idx < *s_addr_idx) {
+ addr_idx++;
+ continue;
+ }
+ err = rtnl_fill_mcaddr(skb, dev, ha, NETLINK_CB(cb->skb).portid,
+ cb->nlh->nlmsg_seq, flags, netnsid);
+ if (err < 0)
+ break;
+ addr_idx++;
+ }
+ netif_addr_unlock_bh(dev);
+
+ *s_addr_idx = err < 0 ? addr_idx : 0;
+
+ return err;
+}
+
+struct rtnl_mcaddr_dump_filter {
+ struct net *tgt_net;
+ int netnsid;
+ int ifindex;
+};
+
+static const struct nla_policy rtnl_mcaddr_dump_policy[IFA_MAX + 1] = {
+ [IFA_TARGET_NETNSID] = { .type = NLA_S32 },
+};
+
+static int rtnl_valid_dump_mcaddr_req(const struct nlmsghdr *nlh,
+ struct sock *sk,
+ struct rtnl_mcaddr_dump_filter *filter,
+ struct netlink_ext_ack *extack)
+{
+ struct nlattr *tb[IFA_MAX + 1];
+ struct ifaddrmsg *ifm;
+ int err;
+
+ ifm = nlmsg_payload(nlh, sizeof(*ifm));
+ if (!ifm) {
+ NL_SET_ERR_MSG(extack,
+ "Invalid header for multicast dump request");
+ return -EINVAL;
+ }
+
+ if (ifm->ifa_prefixlen || ifm->ifa_flags || ifm->ifa_scope) {
+ NL_SET_ERR_MSG(extack,
+ "Invalid values in multicast dump header");
+ return -EINVAL;
+ }
+
+ err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX,
+ rtnl_mcaddr_dump_policy, extack);
+ if (err < 0)
+ return err;
+
+ if (tb[IFA_TARGET_NETNSID]) {
+ struct net *net;
+
+ filter->netnsid = nla_get_s32(tb[IFA_TARGET_NETNSID]);
+ net = rtnl_get_net_ns_capable(sk, filter->netnsid);
+ if (IS_ERR(net)) {
+ NL_SET_ERR_MSG(extack,
+ "Invalid target network namespace id");
+ return PTR_ERR(net);
+ }
+ filter->tgt_net = net;
+ }
+
+ filter->ifindex = ifm->ifa_index;
+
+ return 0;
+}
+
+static int rtnl_dump_mcaddr(struct sk_buff *skb, struct netlink_callback *cb)
+{
+ struct rtnl_mcaddr_dump_filter filter = {
+ .tgt_net = sock_net(skb->sk),
+ .netnsid = -1,
+ };
+ unsigned int flags = NLM_F_MULTI;
+ struct {
+ unsigned long ifindex;
+ int addr_idx;
+ } *ctx = (void *)cb->ctx;
+ struct net_device *dev;
+ int err;
+
+ err = rtnl_valid_dump_mcaddr_req(cb->nlh, skb->sk, &filter,
+ cb->extack);
+ if (err < 0)
+ return err;
+
+ rcu_read_lock();
+
+ if (filter.ifindex) {
+ cb->answer_flags |= NLM_F_DUMP_FILTERED;
+ flags |= NLM_F_DUMP_FILTERED;
+ dev = dev_get_by_index_rcu(filter.tgt_net, filter.ifindex);
+ if (!dev) {
+ err = -ENODEV;
+ goto out;
+ }
+ err = rtnl_dump_mcaddr_dev(dev, skb, cb, &ctx->addr_idx, flags,
+ filter.netnsid);
+ goto out;
+ }
+
+ for_each_netdev_dump(filter.tgt_net, dev, ctx->ifindex) {
+ err = rtnl_dump_mcaddr_dev(dev, skb, cb, &ctx->addr_idx, flags,
+ filter.netnsid);
+ if (err < 0)
+ break;
+ }
+out:
+ rcu_read_unlock();
+ if (filter.netnsid >= 0)
+ put_net(filter.tgt_net);
+ return err;
+}
+
struct sk_buff *rtmsg_ifinfo_build_skb(int type, struct net_device *dev,
unsigned int change,
u32 event, gfp_t flags, int *new_nsid,
@@ -7251,6 +7414,8 @@ static const struct rtnl_msg_handler
rtnetlink_rtnl_msg_handlers[] __initconst =
{.msgtype = RTM_SETSTATS, .doit = rtnl_stats_set},
{.msgtype = RTM_NEWLINKPROP, .doit = rtnl_newlinkprop},
{.msgtype = RTM_DELLINKPROP, .doit = rtnl_dellinkprop},
+ {.protocol = PF_PACKET, .msgtype = RTM_GETMULTICAST,
+ .dumpit = rtnl_dump_mcaddr, .flags = RTNL_FLAG_DUMP_UNLOCKED},
{.protocol = PF_BRIDGE, .msgtype = RTM_GETLINK,
.dumpit = rtnl_bridge_getlink},
{.protocol = PF_BRIDGE, .msgtype = RTM_DELLINK,
--
2.43.0
