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mctp: Add neighbour netlink interface
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This change adds the netlink interfaces for manipulating the MCTP
neighbour table.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Matt Johnston authored and David S. Miller committed Jul 29, 2021
1 parent 4d8b931 commit 831119f
Showing 1 changed file with 204 additions and 3 deletions.
207 changes: 204 additions & 3 deletions net/mctp/neigh.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,9 +21,9 @@
#include <net/netlink.h>
#include <net/sock.h>

static int __always_unused mctp_neigh_add(struct mctp_dev *mdev, mctp_eid_t eid,
enum mctp_neigh_source source,
size_t lladdr_len, const void *lladdr)
static int mctp_neigh_add(struct mctp_dev *mdev, mctp_eid_t eid,
enum mctp_neigh_source source,
size_t lladdr_len, const void *lladdr)
{
struct net *net = dev_net(mdev->dev);
struct mctp_neigh *neigh;
Expand Down Expand Up @@ -85,6 +85,196 @@ void mctp_neigh_remove_dev(struct mctp_dev *mdev)
mutex_unlock(&net->mctp.neigh_lock);
}

// TODO: add a "source" flag so netlink can only delete static neighbours?
static int mctp_neigh_remove(struct mctp_dev *mdev, mctp_eid_t eid)
{
struct net *net = dev_net(mdev->dev);
struct mctp_neigh *neigh, *tmp;
bool dropped = false;

mutex_lock(&net->mctp.neigh_lock);
list_for_each_entry_safe(neigh, tmp, &net->mctp.neighbours, list) {
if (neigh->dev == mdev && neigh->eid == eid) {
list_del_rcu(&neigh->list);
/* TODO: immediate RTM_DELNEIGH */
call_rcu(&neigh->rcu, __mctp_neigh_free);
dropped = true;
}
}

mutex_unlock(&net->mctp.neigh_lock);
return dropped ? 0 : -ENOENT;
}

static const struct nla_policy nd_mctp_policy[NDA_MAX + 1] = {
[NDA_DST] = { .type = NLA_U8 },
[NDA_LLADDR] = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
};

static int mctp_rtm_newneigh(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(skb->sk);
struct net_device *dev;
struct mctp_dev *mdev;
struct ndmsg *ndm;
struct nlattr *tb[NDA_MAX + 1];
int rc;
mctp_eid_t eid;
void *lladdr;
int lladdr_len;

rc = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, nd_mctp_policy,
extack);
if (rc < 0) {
NL_SET_ERR_MSG(extack, "lladdr too large?");
return rc;
}

if (!tb[NDA_DST]) {
NL_SET_ERR_MSG(extack, "Neighbour EID must be specified");
return -EINVAL;
}

if (!tb[NDA_LLADDR]) {
NL_SET_ERR_MSG(extack, "Neighbour lladdr must be specified");
return -EINVAL;
}

eid = nla_get_u8(tb[NDA_DST]);
if (!mctp_address_ok(eid)) {
NL_SET_ERR_MSG(extack, "Invalid neighbour EID");
return -EINVAL;
}

lladdr = nla_data(tb[NDA_LLADDR]);
lladdr_len = nla_len(tb[NDA_LLADDR]);

ndm = nlmsg_data(nlh);

dev = __dev_get_by_index(net, ndm->ndm_ifindex);
if (!dev)
return -ENODEV;

mdev = mctp_dev_get_rtnl(dev);
if (!mdev)
return -ENODEV;

if (lladdr_len != dev->addr_len) {
NL_SET_ERR_MSG(extack, "Wrong lladdr length");
return -EINVAL;
}

return mctp_neigh_add(mdev, eid, MCTP_NEIGH_STATIC,
lladdr_len, lladdr);
}

static int mctp_rtm_delneigh(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(skb->sk);
struct nlattr *tb[NDA_MAX + 1];
struct net_device *dev;
struct mctp_dev *mdev;
struct ndmsg *ndm;
int rc;
mctp_eid_t eid;

rc = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, nd_mctp_policy,
extack);
if (rc < 0) {
NL_SET_ERR_MSG(extack, "incorrect format");
return rc;
}

if (!tb[NDA_DST]) {
NL_SET_ERR_MSG(extack, "Neighbour EID must be specified");
return -EINVAL;
}
eid = nla_get_u8(tb[NDA_DST]);

ndm = nlmsg_data(nlh);
dev = __dev_get_by_index(net, ndm->ndm_ifindex);
if (!dev)
return -ENODEV;

mdev = mctp_dev_get_rtnl(dev);
if (!mdev)
return -ENODEV;

return mctp_neigh_remove(mdev, eid);
}

static int mctp_fill_neigh(struct sk_buff *skb, u32 portid, u32 seq, int event,
unsigned int flags, struct mctp_neigh *neigh)
{
struct net_device *dev = neigh->dev->dev;
struct nlmsghdr *nlh;
struct ndmsg *hdr;

nlh = nlmsg_put(skb, portid, seq, event, sizeof(*hdr), flags);
if (!nlh)
return -EMSGSIZE;

hdr = nlmsg_data(nlh);
hdr->ndm_family = AF_MCTP;
hdr->ndm_ifindex = dev->ifindex;
hdr->ndm_state = 0; // TODO other state bits?
if (neigh->source == MCTP_NEIGH_STATIC)
hdr->ndm_state |= NUD_PERMANENT;
hdr->ndm_flags = 0;
hdr->ndm_type = RTN_UNICAST; // TODO: is loopback RTN_LOCAL?

if (nla_put_u8(skb, NDA_DST, neigh->eid))
goto cancel;

if (nla_put(skb, NDA_LLADDR, dev->addr_len, neigh->ha))
goto cancel;

nlmsg_end(skb, nlh);

return 0;
cancel:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}

static int mctp_rtm_getneigh(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
int rc, idx, req_ifindex;
struct mctp_neigh *neigh;
struct ndmsg *ndmsg;
struct {
int idx;
} *cbctx = (void *)cb->ctx;

ndmsg = nlmsg_data(cb->nlh);
req_ifindex = ndmsg->ndm_ifindex;

idx = 0;
rcu_read_lock();
list_for_each_entry_rcu(neigh, &net->mctp.neighbours, list) {
if (idx < cbctx->idx)
goto cont;

rc = 0;
if (req_ifindex == 0 || req_ifindex == neigh->dev->dev->ifindex)
rc = mctp_fill_neigh(skb, NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
RTM_NEWNEIGH, NLM_F_MULTI, neigh);

if (rc)
break;
cont:
idx++;
}
rcu_read_unlock();

cbctx->idx = idx;
return skb->len;
}

int mctp_neigh_lookup(struct mctp_dev *mdev, mctp_eid_t eid, void *ret_hwaddr)
{
struct net *net = dev_net(mdev->dev);
Expand All @@ -111,6 +301,7 @@ static int __net_init mctp_neigh_net_init(struct net *net)
struct netns_mctp *ns = &net->mctp;

INIT_LIST_HEAD(&ns->neighbours);
mutex_init(&ns->neigh_lock);
return 0;
}

Expand All @@ -132,10 +323,20 @@ static struct pernet_operations mctp_net_ops = {

int __init mctp_neigh_init(void)
{
rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_NEWNEIGH,
mctp_rtm_newneigh, NULL, 0);
rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_DELNEIGH,
mctp_rtm_delneigh, NULL, 0);
rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_GETNEIGH,
NULL, mctp_rtm_getneigh, 0);

return register_pernet_subsys(&mctp_net_ops);
}

void __exit mctp_neigh_exit(void)
{
unregister_pernet_subsys(&mctp_net_ops);
rtnl_unregister(PF_MCTP, RTM_GETNEIGH);
rtnl_unregister(PF_MCTP, RTM_DELNEIGH);
rtnl_unregister(PF_MCTP, RTM_NEWNEIGH);
}

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