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Message-Id: <20220704095845.365359-1-equinox@diac24.net>
Date: Mon, 4 Jul 2022 11:58:45 +0200
From: David Lamparter <equinox@...c24.net>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
David Ahern <dsahern@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
David Lamparter <equinox@...c24.net>
Subject: [PATCH net-next v2] net: ip6mr: add RTM_GETROUTE netlink op
The IPv6 multicast routing code previously implemented only the dump
variant of RTM_GETROUTE. Implement single MFC item retrieval by copying
and adapting the respective IPv4 code.
Tested against FRRouting's IPv6 PIM stack.
Signed-off-by: David Lamparter <equinox@...c24.net>
Cc: David Ahern <dsahern@...nel.org>
---
v2: changeover to strict netlink attribute parsing. Doing so actually
exposed a bunch of other issues, first and foremost that rtm_ipv6_policy
does not have RTA_SRC or RTA_DST. This made reusing that policy rather
pointless so I changed it to use a separate rtm_ipv6_mr_policy.
Thanks again dsahern@ for the feedback on the previous version!
---
net/ipv6/ip6mr.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 127 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index ec6e1509fc7c..95dc366a2d9b 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -95,6 +95,8 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt,
static void mr6_netlink_event(struct mr_table *mrt, struct mfc6_cache *mfc,
int cmd);
static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pkt);
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+ struct netlink_ext_ack *extack);
static int ip6mr_rtm_dumproute(struct sk_buff *skb,
struct netlink_callback *cb);
static void mroute_clean_tables(struct mr_table *mrt, int flags);
@@ -1390,7 +1392,7 @@ int __init ip6_mr_init(void)
}
#endif
err = rtnl_register_module(THIS_MODULE, RTNL_FAMILY_IP6MR, RTM_GETROUTE,
- NULL, ip6mr_rtm_dumproute, 0);
+ ip6mr_rtm_getroute, ip6mr_rtm_dumproute, 0);
if (err == 0)
return 0;
@@ -2510,6 +2512,130 @@ static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pk
rtnl_set_sk_err(net, RTNLGRP_IPV6_MROUTE_R, -ENOBUFS);
}
+const struct nla_policy rtm_ipv6_mr_policy[RTA_MAX + 1] = {
+ [RTA_UNSPEC] = { .strict_start_type = RTA_UNSPEC },
+ [RTA_SRC] = NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
+ [RTA_DST] = NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
+ [RTA_TABLE] = { .type = NLA_U32 },
+};
+
+static int ip6mr_rtm_valid_getroute_req(struct sk_buff *skb,
+ const struct nlmsghdr *nlh,
+ struct nlattr **tb,
+ struct netlink_ext_ack *extack)
+{
+ struct rtmsg *rtm;
+ int i, err;
+
+ if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
+ NL_SET_ERR_MSG(extack, "ipv6: Invalid header for multicast route get request");
+ return -EINVAL;
+ }
+
+ rtm = nlmsg_data(nlh);
+ if ((rtm->rtm_src_len && rtm->rtm_src_len != 128) ||
+ (rtm->rtm_dst_len && rtm->rtm_dst_len != 128) ||
+ rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
+ rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
+ NL_SET_ERR_MSG(extack,
+ "ipv6: Invalid values in header for multicast route get request");
+ return -EINVAL;
+ }
+
+ err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv6_mr_policy,
+ extack);
+ if (err)
+ return err;
+
+ if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
+ (tb[RTA_DST] && !rtm->rtm_dst_len)) {
+ NL_SET_ERR_MSG(extack, "ipv6: rtm_src_len and rtm_dst_len must be 128 for IPv6");
+ return -EINVAL;
+ }
+
+ /* rtm_ipv6_mr_policy does not list other attributes right now, but
+ * future changes may reuse rtm_ipv6_mr_policy with adding further
+ * attrs. Enforce the subset.
+ */
+ for (i = 0; i <= RTA_MAX; i++) {
+ if (!tb[i])
+ continue;
+
+ switch (i) {
+ case RTA_SRC:
+ case RTA_DST:
+ case RTA_TABLE:
+ break;
+ default:
+ NL_SET_ERR_MSG_ATTR(extack, tb[i],
+ "ipv6: Unsupported attribute in multicast route get request");
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+ struct netlink_ext_ack *extack)
+{
+ struct net *net = sock_net(in_skb->sk);
+ struct nlattr *tb[RTA_MAX + 1];
+ struct sk_buff *skb = NULL;
+ struct mfc6_cache *cache;
+ struct mr_table *mrt;
+ struct in6_addr src = {}, grp = {};
+ u32 tableid;
+ int err;
+
+ err = ip6mr_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
+ if (err < 0)
+ goto errout;
+
+ if (tb[RTA_SRC])
+ src = nla_get_in6_addr(tb[RTA_SRC]);
+ if (tb[RTA_DST])
+ grp = nla_get_in6_addr(tb[RTA_DST]);
+ tableid = tb[RTA_TABLE] ? nla_get_u32(tb[RTA_TABLE]) : 0;
+
+ mrt = ip6mr_get_table(net, tableid ? tableid : RT_TABLE_DEFAULT);
+ if (!mrt) {
+ NL_SET_ERR_MSG_MOD(extack, "ipv6 MR table does not exist");
+ err = -ENOENT;
+ goto errout_free;
+ }
+
+ /* entries are added/deleted only under RTNL */
+ rcu_read_lock();
+ cache = ip6mr_cache_find(mrt, &src, &grp);
+ rcu_read_unlock();
+ if (!cache) {
+ NL_SET_ERR_MSG_MOD(extack, "ipv6 MR cache entry not found");
+ err = -ENOENT;
+ goto errout_free;
+ }
+
+ skb = nlmsg_new(mr6_msgsize(false, mrt->maxvif), GFP_KERNEL);
+ if (!skb) {
+ err = -ENOBUFS;
+ goto errout_free;
+ }
+
+ err = ip6mr_fill_mroute(mrt, skb, NETLINK_CB(in_skb).portid,
+ nlh->nlmsg_seq, cache, RTM_NEWROUTE, 0);
+ if (err < 0)
+ goto errout_free;
+
+ err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+
+errout:
+ return err;
+
+errout_free:
+ kfree_skb(skb);
+ goto errout;
+}
+
static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
{
const struct nlmsghdr *nlh = cb->nlh;
--
2.36.1
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