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Date: Mon, 4 Jul 2022 12:52:23 +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>, Nikolay Aleksandrov <razor@...ckwall.org> Subject: [PATCH net-next v3] 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> Cc: Nikolay Aleksandrov <razor@...ckwall.org> --- 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 | 122 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 121 insertions(+), 1 deletion(-) diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index ec6e1509fc7c..9909ff77f5a6 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 +2512,124 @@ 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_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; + + err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv6_mr_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(extack, + "ipv6: 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(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 in6_addr src = {}, grp = {}; + struct nlattr *tb[RTA_MAX + 1]; + struct sk_buff *skb = NULL; + struct mfc6_cache *cache; + struct mr_table *mrt; + 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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