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_PERMANENT marks entries added with SIOCADDMULTI
(netdev_hw_addr::global_use, "static" in "ip maddr")
- ifa_scope is RT_SCOPE_LINK
This covers every column of /proc/net/dev_mcast. Strict requests are
validated like the IPv4 dump, except that no attributes are accepted;
a non-zero ifa_index restricts the dump to that device. The dump runs
under RCU and netif_addr_lock_bh() and does not need RTNL.
Signed-off-by: Yuyang Huang <[email protected]>
---
net/core/rtnetlink.c | 132 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 132 insertions(+)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 81c5a6104dea..5e83232c1504 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -4566,6 +4566,136 @@ 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)
+{
+ 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 = ha->global_use ? IFA_F_PERMANENT : 0;
+ ifm->ifa_scope = RT_SCOPE_LINK;
+ ifm->ifa_index = dev->ifindex;
+
+ if (nla_put(skb, IFA_MULTICAST, dev->addr_len, ha->addr) ||
+ nla_put_u32(skb, IFA_MC_USERS, ha->refcount)) {
+ 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)
+{
+ 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);
+ if (err < 0)
+ break;
+ addr_idx++;
+ }
+ netif_addr_unlock_bh(dev);
+
+ *s_addr_idx = err < 0 ? addr_idx : 0;
+
+ return err;
+}
+
+static int rtnl_valid_dump_mcaddr_req(const struct nlmsghdr *nlh,
+ struct netlink_ext_ack *extack,
+ int *pifindex)
+{
+ struct ifaddrmsg *ifm;
+
+ 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;
+ }
+
+ if (nlmsg_attrlen(nlh, sizeof(*ifm))) {
+ NL_SET_ERR_MSG(extack,
+ "Invalid data after multicast dump header");
+ return -EINVAL;
+ }
+
+ *pifindex = ifm->ifa_index;
+
+ return 0;
+}
+
+static int rtnl_dump_mcaddr(struct sk_buff *skb, struct netlink_callback *cb)
+{
+ struct net *net = sock_net(skb->sk);
+ unsigned int flags = NLM_F_MULTI;
+ struct {
+ unsigned long ifindex;
+ int addr_idx;
+ } *ctx = (void *)cb->ctx;
+ struct net_device *dev;
+ int ifindex = 0;
+ int err = 0;
+
+ if (cb->strict_check) {
+ err = rtnl_valid_dump_mcaddr_req(cb->nlh, cb->extack,
+ &ifindex);
+ if (err < 0)
+ return err;
+ }
+
+ rcu_read_lock();
+
+ if (ifindex) {
+ cb->answer_flags |= NLM_F_DUMP_FILTERED;
+ flags |= NLM_F_DUMP_FILTERED;
+ dev = dev_get_by_index_rcu(net, ifindex);
+ if (!dev) {
+ err = -ENODEV;
+ goto out;
+ }
+ err = rtnl_dump_mcaddr_dev(dev, skb, cb, &ctx->addr_idx, flags);
+ goto out;
+ }
+
+ for_each_netdev_dump(net, dev, ctx->ifindex) {
+ err = rtnl_dump_mcaddr_dev(dev, skb, cb, &ctx->addr_idx,
+ flags);
+ if (err < 0)
+ break;
+ }
+out:
+ rcu_read_unlock();
+ 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 +7381,8 @@ 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
