mctp: emit RTM_NEWADDR and RTM_DELADDR

Userspace can receive notification of MCTP address changes via
RTNLGRP_MCTP_IFADDR rtnetlink multicast group.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20211220023104.1965509-1-matt@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index 5888492a5257b450d6518718a80c82a4d6c17b93..93d934cc4613dbc04339adcc7ce4a9f4fdf569d6 100644 (file)
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -754,6 +754,8 @@ enum rtnetlink_groups {
 #define RTNLGRP_NEXTHOP                RTNLGRP_NEXTHOP
        RTNLGRP_BRVLAN,
 #define RTNLGRP_BRVLAN         RTNLGRP_BRVLAN
+       RTNLGRP_MCTP_IFADDR,
+#define RTNLGRP_MCTP_IFADDR    RTNLGRP_MCTP_IFADDR
        __RTNLGRP_MAX
 };
 #define RTNLGRP_MAX    (__RTNLGRP_MAX - 1)

diff --git a/net/mctp/device.c b/net/mctp/device.c
index 8799ee77e7b7fa09bdf042f87fd494bd8f43df2e..ef2755f82f87b38d604db30498c250c489ac7a53 100644 (file)
--- a/net/mctp/device.c
+++ b/net/mctp/device.c
@@ -35,14 +35,24 @@ struct mctp_dev *mctp_dev_get_rtnl(const struct net_device *dev)
        return rtnl_dereference(dev->mctp_ptr);
 }
 
-static int mctp_fill_addrinfo(struct sk_buff *skb, struct netlink_callback *cb,
-                             struct mctp_dev *mdev, mctp_eid_t eid)
+static int mctp_addrinfo_size(void)
+{
+       return NLMSG_ALIGN(sizeof(struct ifaddrmsg))
+               + nla_total_size(1) // IFA_LOCAL
+               + nla_total_size(1) // IFA_ADDRESS
+               ;
+}
+
+/* flag should be NLM_F_MULTI for dump calls */
+static int mctp_fill_addrinfo(struct sk_buff *skb,
+                             struct mctp_dev *mdev, mctp_eid_t eid,
+                             int msg_type, u32 portid, u32 seq, int flag)
 {
        struct ifaddrmsg *hdr;
        struct nlmsghdr *nlh;
 
-       nlh = nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
-                       RTM_NEWADDR, sizeof(*hdr), NLM_F_MULTI);
+       nlh = nlmsg_put(skb, portid, seq,
+                       msg_type, sizeof(*hdr), flag);
        if (!nlh)
                return -EMSGSIZE;
 
@@ -72,10 +82,14 @@ static int mctp_dump_dev_addrinfo(struct mctp_dev *mdev, struct sk_buff *skb,
                                  struct netlink_callback *cb)
 {
        struct mctp_dump_cb *mcb = (void *)cb->ctx;
+       u32 portid, seq;
        int rc = 0;
 
+       portid = NETLINK_CB(cb->skb).portid;
+       seq = cb->nlh->nlmsg_seq;
        for (; mcb->a_idx < mdev->num_addrs; mcb->a_idx++) {
-               rc = mctp_fill_addrinfo(skb, cb, mdev, mdev->addrs[mcb->a_idx]);
+               rc = mctp_fill_addrinfo(skb, mdev, mdev->addrs[mcb->a_idx],
+                                       RTM_NEWADDR, portid, seq, NLM_F_MULTI);
                if (rc < 0)
                        break;
        }
@@ -127,6 +141,32 @@ out:
        return skb->len;
 }
 
+static void mctp_addr_notify(struct mctp_dev *mdev, mctp_eid_t eid, int msg_type,
+                            struct sk_buff *req_skb, struct nlmsghdr *req_nlh)
+{
+       u32 portid = NETLINK_CB(req_skb).portid;
+       struct net *net = dev_net(mdev->dev);
+       struct sk_buff *skb;
+       int rc = -ENOBUFS;
+
+       skb = nlmsg_new(mctp_addrinfo_size(), GFP_KERNEL);
+       if (!skb)
+               goto out;
+
+       rc = mctp_fill_addrinfo(skb, mdev, eid, msg_type,
+                               portid, req_nlh->nlmsg_seq, 0);
+       if (rc < 0) {
+               WARN_ON_ONCE(rc == -EMSGSIZE);
+               goto out;
+       }
+
+       rtnl_notify(skb, net, portid, RTNLGRP_MCTP_IFADDR, req_nlh, GFP_KERNEL);
+       return;
+out:
+       kfree_skb(skb);
+       rtnl_set_sk_err(net, RTNLGRP_MCTP_IFADDR, rc);
+}
+
 static const struct nla_policy ifa_mctp_policy[IFA_MAX + 1] = {
        [IFA_ADDRESS]           = { .type = NLA_U8 },
        [IFA_LOCAL]             = { .type = NLA_U8 },
@@ -189,6 +229,7 @@ static int mctp_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
 
        kfree(tmp_addrs);
 
+       mctp_addr_notify(mdev, addr->s_addr, RTM_NEWADDR, skb, nlh);
        mctp_route_add_local(mdev, addr->s_addr);
 
        return 0;
@@ -244,6 +285,8 @@ static int mctp_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
        mdev->num_addrs--;
        spin_unlock_irqrestore(&mdev->addrs_lock, flags);
 
+       mctp_addr_notify(mdev, addr->s_addr, RTM_DELADDR, skb, nlh);
+
        return 0;
 }