From 03c0566542f4c7a45ce3193f27cbf5700b506c18 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 3 Mar 2015 19:13:56 -0600 Subject: [PATCH] mpls: Netlink commands to add, remove, and dump routes This change adds two new netlink routing attributes: RTA_VIA and RTA_NEWDST. RTA_VIA specifies the specifies the next machine to send a packet to like RTA_GATEWAY. RTA_VIA differs from RTA_GATEWAY in that it includes the address family of the address of the next machine to send a packet to. Currently the MPLS code supports addresses in AF_INET, AF_INET6 and AF_PACKET. For AF_INET and AF_INET6 the destination mac address is acquired from the neighbour table. For AF_PACKET the destination mac_address is specified in the netlink configuration. I think raw destination mac address support with the family AF_PACKET will prove useful. There is MPLS-TP which is defined to operate on machines that do not support internet packets of any flavor. Further seem to be corner cases where it can be useful. At this point I don't care much either way. RTA_NEWDST specifies the destination address to forward the packet with. MPLS typically changes it's destination address at every hop. For a swap operation RTA_NEWDST is specified with a length of one label. For a push operation RTA_NEWDST is specified with two or more labels. For a pop operation RTA_NEWDST is not specified or equivalently an emtpy RTAN_NEWDST is specified. Those new netlink attributes are used to implement handling of rt-netlink RTM_NEWROUTE, RTM_DELROUTE, and RTM_GETROUTE messages, to maintain the MPLS label table. rtm_to_route_config parses a netlink RTM_NEWROUTE or RTM_DELROUTE message, verify no unhandled attributes or unhandled values are present and sets up the data structures for mpls_route_add and mpls_route_del. I did my best to match up with the existing conventions with the caveats that MPLS addresses are all destination-specific-addresses, and so don't properly have a scope. Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller --- include/uapi/linux/rtnetlink.h | 8 ++ net/mpls/af_mpls.c | 229 +++++++++++++++++++++++++++++++++ 2 files changed, 237 insertions(+) diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h index 5cc5d66bf519..bad65550ae3e 100644 --- a/include/uapi/linux/rtnetlink.h +++ b/include/uapi/linux/rtnetlink.h @@ -303,6 +303,8 @@ enum rtattr_type_t { RTA_TABLE, RTA_MARK, RTA_MFC_STATS, + RTA_VIA, + RTA_NEWDST, __RTA_MAX }; @@ -344,6 +346,12 @@ struct rtnexthop { #define RTNH_SPACE(len) RTNH_ALIGN(RTNH_LENGTH(len)) #define RTNH_DATA(rtnh) ((struct rtattr*)(((char*)(rtnh)) + RTNH_LENGTH(0))) +/* RTA_VIA */ +struct rtvia { + __kernel_sa_family_t rtvia_family; + __u8 rtvia_addr[0]; +}; + /* RTM_CACHEINFO */ struct rta_cacheinfo { diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index 2d6612a10e30..b4d7cec398d2 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -212,6 +212,11 @@ static struct packet_type mpls_packet_type __read_mostly = { .func = mpls_forward, }; +const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = { + [RTA_DST] = { .type = NLA_U32 }, + [RTA_OIF] = { .type = NLA_U32 }, +}; + struct mpls_route_config { u32 rc_protocol; u32 rc_ifindex; @@ -410,6 +415,22 @@ static struct notifier_block mpls_dev_notifier = { .notifier_call = mpls_dev_notify, }; +static int nla_put_via(struct sk_buff *skb, + u16 family, const void *addr, int alen) +{ + struct nlattr *nla; + struct rtvia *via; + + nla = nla_reserve(skb, RTA_VIA, alen + 2); + if (!nla) + return -EMSGSIZE; + + via = nla_data(nla); + via->rtvia_family = family; + memcpy(via->rtvia_addr, addr, alen); + return 0; +} + int nla_put_labels(struct sk_buff *skb, int attrtype, u8 labels, const u32 label[]) { @@ -467,6 +488,210 @@ int nla_get_labels(const struct nlattr *nla, return 0; } +static int rtm_to_route_config(struct sk_buff *skb, struct nlmsghdr *nlh, + struct mpls_route_config *cfg) +{ + struct rtmsg *rtm; + struct nlattr *tb[RTA_MAX+1]; + int index; + int err; + + err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_mpls_policy); + if (err < 0) + goto errout; + + err = -EINVAL; + rtm = nlmsg_data(nlh); + memset(cfg, 0, sizeof(*cfg)); + + if (rtm->rtm_family != AF_MPLS) + goto errout; + if (rtm->rtm_dst_len != 20) + goto errout; + if (rtm->rtm_src_len != 0) + goto errout; + if (rtm->rtm_tos != 0) + goto errout; + if (rtm->rtm_table != RT_TABLE_MAIN) + goto errout; + /* Any value is acceptable for rtm_protocol */ + + /* As mpls uses destination specific addresses + * (or source specific address in the case of multicast) + * all addresses have universal scope. + */ + if (rtm->rtm_scope != RT_SCOPE_UNIVERSE) + goto errout; + if (rtm->rtm_type != RTN_UNICAST) + goto errout; + if (rtm->rtm_flags != 0) + goto errout; + + cfg->rc_label = LABEL_NOT_SPECIFIED; + cfg->rc_protocol = rtm->rtm_protocol; + cfg->rc_nlflags = nlh->nlmsg_flags; + cfg->rc_nlinfo.portid = NETLINK_CB(skb).portid; + cfg->rc_nlinfo.nlh = nlh; + cfg->rc_nlinfo.nl_net = sock_net(skb->sk); + + for (index = 0; index <= RTA_MAX; index++) { + struct nlattr *nla = tb[index]; + if (!nla) + continue; + + switch(index) { + case RTA_OIF: + cfg->rc_ifindex = nla_get_u32(nla); + break; + case RTA_NEWDST: + if (nla_get_labels(nla, MAX_NEW_LABELS, + &cfg->rc_output_labels, + cfg->rc_output_label)) + goto errout; + break; + case RTA_DST: + { + u32 label_count; + if (nla_get_labels(nla, 1, &label_count, + &cfg->rc_label)) + goto errout; + + /* The first 16 labels are reserved, and may not be set */ + if (cfg->rc_label < 16) + goto errout; + + break; + } + case RTA_VIA: + { + struct rtvia *via = nla_data(nla); + cfg->rc_via_family = via->rtvia_family; + cfg->rc_via_alen = nla_len(nla) - 2; + if (cfg->rc_via_alen > MAX_VIA_ALEN) + goto errout; + + /* Validate the address family */ + switch(cfg->rc_via_family) { + case AF_PACKET: + break; + case AF_INET: + if (cfg->rc_via_alen != 4) + goto errout; + break; + case AF_INET6: + if (cfg->rc_via_alen != 16) + goto errout; + break; + default: + /* Unsupported address family */ + goto errout; + } + + memcpy(cfg->rc_via, via->rtvia_addr, cfg->rc_via_alen); + break; + } + default: + /* Unsupported attribute */ + goto errout; + } + } + + err = 0; +errout: + return err; +} + +static int mpls_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh) +{ + struct mpls_route_config cfg; + int err; + + err = rtm_to_route_config(skb, nlh, &cfg); + if (err < 0) + return err; + + return mpls_route_del(&cfg); +} + + +static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh) +{ + struct mpls_route_config cfg; + int err; + + err = rtm_to_route_config(skb, nlh, &cfg); + if (err < 0) + return err; + + return mpls_route_add(&cfg); +} + +static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event, + u32 label, struct mpls_route *rt, int flags) +{ + struct nlmsghdr *nlh; + struct rtmsg *rtm; + + nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags); + if (nlh == NULL) + return -EMSGSIZE; + + rtm = nlmsg_data(nlh); + rtm->rtm_family = AF_MPLS; + rtm->rtm_dst_len = 20; + rtm->rtm_src_len = 0; + rtm->rtm_tos = 0; + rtm->rtm_table = RT_TABLE_MAIN; + rtm->rtm_protocol = rt->rt_protocol; + rtm->rtm_scope = RT_SCOPE_UNIVERSE; + rtm->rtm_type = RTN_UNICAST; + rtm->rtm_flags = 0; + + if (rt->rt_labels && + nla_put_labels(skb, RTA_NEWDST, rt->rt_labels, rt->rt_label)) + goto nla_put_failure; + if (nla_put_via(skb, rt->rt_via_family, rt->rt_via, rt->rt_via_alen)) + goto nla_put_failure; + if (rt->rt_dev && nla_put_u32(skb, RTA_OIF, rt->rt_dev->ifindex)) + goto nla_put_failure; + if (nla_put_labels(skb, RTA_DST, 1, &label)) + goto nla_put_failure; + + nlmsg_end(skb, nlh); + return 0; + +nla_put_failure: + nlmsg_cancel(skb, nlh); + return -EMSGSIZE; +} + +static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb) +{ + struct net *net = sock_net(skb->sk); + unsigned int index; + + ASSERT_RTNL(); + + index = cb->args[0]; + if (index < 16) + index = 16; + + for (; index < net->mpls.platform_labels; index++) { + struct mpls_route *rt; + rt = net->mpls.platform_label[index]; + if (!rt) + continue; + + if (mpls_dump_route(skb, NETLINK_CB(cb->skb).portid, + cb->nlh->nlmsg_seq, RTM_NEWROUTE, + index, rt, NLM_F_MULTI) < 0) + break; + } + cb->args[0] = index; + + return skb->len; +} + static int resize_platform_label_table(struct net *net, size_t limit) { size_t size = sizeof(struct mpls_route *) * limit; @@ -662,6 +887,9 @@ static int __init mpls_init(void) dev_add_pack(&mpls_packet_type); + rtnl_register(PF_MPLS, RTM_NEWROUTE, mpls_rtm_newroute, NULL, NULL); + rtnl_register(PF_MPLS, RTM_DELROUTE, mpls_rtm_delroute, NULL, NULL); + rtnl_register(PF_MPLS, RTM_GETROUTE, NULL, mpls_dump_routes, NULL); err = 0; out: return err; @@ -674,6 +902,7 @@ module_init(mpls_init); static void __exit mpls_exit(void) { + rtnl_unregister_all(PF_MPLS); dev_remove_pack(&mpls_packet_type); unregister_netdevice_notifier(&mpls_dev_notifier); unregister_pernet_subsys(&mpls_net_ops); -- 2.20.1