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Message-Id: <20220712121002.262794-1-equinox@diac24.net>
Date: Tue, 12 Jul 2022 14:10:02 +0200
From: David Lamparter <equinox@...c24.net>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
David Lamparter <equinox@...c24.net>,
Nikolay Aleksandrov <razor@...ckwall.org>,
David Ahern <dsahern@...nel.org>,
Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next v6] 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>
Reviewed-by: Nikolay Aleksandrov <razor@...ckwall.org>
Reviewed-by: David Ahern <dsahern@...nel.org>
Cc: Jakub Kicinski <kuba@...nel.org>
---
v6: more style polishing (replace goto with return, ?:), Thanks Jakub!
v5: consistently use NL_SET_ERR_MSG_MOD for "ipv6: " prefix
v4: rename policy to indicate it is dedicated for getroute, remove
extra validation loop to reject attrs, and add missing "static".
v3: reorder/remove some redundant bits, fix style. Thanks Nikolay for
pointing them out. The "extra" validation loop is still there for the
time being; happy to drop it if that's the consensus.
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 | 93 +++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 92 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index ec6e1509fc7c..d546fc09d803 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 +2512,95 @@ static void mrt6msg_netlink_event(const struct mr_table *mrt, struct sk_buff *pk
rtnl_set_sk_err(net, RTNLGRP_IPV6_MROUTE_R, -ENOBUFS);
}
+static const struct nla_policy ip6mr_getroute_policy[RTA_MAX + 1] = {
+ [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 err;
+
+ err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, ip6mr_getroute_policy,
+ extack);
+ if (err)
+ return err;
+
+ 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_MOD(extack,
+ "Invalid values in header for multicast route get request");
+ return -EINVAL;
+ }
+
+ if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
+ (tb[RTA_DST] && !rtm->rtm_dst_len)) {
+ NL_SET_ERR_MSG_MOD(extack, "rtm_src_len and rtm_dst_len must be 128 for IPv6");
+ 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 in6_addr src = {}, grp = {};
+ struct nlattr *tb[RTA_MAX + 1];
+ struct mfc6_cache *cache;
+ struct mr_table *mrt;
+ struct sk_buff *skb;
+ u32 tableid;
+ int err;
+
+ err = ip6mr_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
+ if (err < 0)
+ return err;
+
+ 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 ?: RT_TABLE_DEFAULT);
+ if (!mrt) {
+ NL_SET_ERR_MSG_MOD(extack, "MR table does not exist");
+ return -ENOENT;
+ }
+
+ /* 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, "MR cache entry not found");
+ return -ENOENT;
+ }
+
+ skb = nlmsg_new(mr6_msgsize(false, mrt->maxvif), GFP_KERNEL);
+ if (!skb)
+ return -ENOBUFS;
+
+ err = ip6mr_fill_mroute(mrt, skb, NETLINK_CB(in_skb).portid,
+ nlh->nlmsg_seq, cache, RTM_NEWROUTE, 0);
+ if (err < 0) {
+ kfree_skb(skb);
+ return err;
+ }
+
+ return rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
+}
+
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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