root/net/sched/act_mpls.c
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (C) 2019 Netronome Systems, Inc. */

#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mpls.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/tc_act/tc_mpls.h>
#include <net/mpls.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <net/tc_act/tc_mpls.h>
#include <net/tc_wrapper.h>

static struct tc_action_ops act_mpls_ops;

#define ACT_MPLS_TTL_DEFAULT    255

static __be32 tcf_mpls_get_lse(struct mpls_shim_hdr *lse,
                               struct tcf_mpls_params *p, bool set_bos)
{
        u32 new_lse = 0;

        if (lse)
                new_lse = be32_to_cpu(lse->label_stack_entry);

        if (p->tcfm_label != ACT_MPLS_LABEL_NOT_SET) {
                new_lse &= ~MPLS_LS_LABEL_MASK;
                new_lse |= p->tcfm_label << MPLS_LS_LABEL_SHIFT;
        }
        if (p->tcfm_ttl) {
                new_lse &= ~MPLS_LS_TTL_MASK;
                new_lse |= p->tcfm_ttl << MPLS_LS_TTL_SHIFT;
        }
        if (p->tcfm_tc != ACT_MPLS_TC_NOT_SET) {
                new_lse &= ~MPLS_LS_TC_MASK;
                new_lse |= p->tcfm_tc << MPLS_LS_TC_SHIFT;
        }
        if (p->tcfm_bos != ACT_MPLS_BOS_NOT_SET) {
                new_lse &= ~MPLS_LS_S_MASK;
                new_lse |= p->tcfm_bos << MPLS_LS_S_SHIFT;
        } else if (set_bos) {
                new_lse |= 1 << MPLS_LS_S_SHIFT;
        }

        return cpu_to_be32(new_lse);
}

TC_INDIRECT_SCOPE int tcf_mpls_act(struct sk_buff *skb,
                                   const struct tc_action *a,
                                   struct tcf_result *res)
{
        struct tcf_mpls *m = to_mpls(a);
        struct tcf_mpls_params *p;
        __be32 new_lse;
        int mac_len;

        tcf_lastuse_update(&m->tcf_tm);
        bstats_update(this_cpu_ptr(m->common.cpu_bstats), skb);

        /* Ensure 'data' points at mac_header prior calling mpls manipulating
         * functions.
         */
        if (skb_at_tc_ingress(skb)) {
                skb_push_rcsum(skb, skb->mac_len);
                mac_len = skb->mac_len;
        } else {
                mac_len = skb_network_offset(skb);
        }

        p = rcu_dereference_bh(m->mpls_p);

        switch (p->tcfm_action) {
        case TCA_MPLS_ACT_POP:
                if (skb_mpls_pop(skb, p->tcfm_proto, mac_len,
                                 skb->dev && skb->dev->type == ARPHRD_ETHER))
                        goto drop;
                break;
        case TCA_MPLS_ACT_PUSH:
                new_lse = tcf_mpls_get_lse(NULL, p, !eth_p_mpls(skb_protocol(skb, true)));
                if (skb_mpls_push(skb, new_lse, p->tcfm_proto, mac_len,
                                  skb->dev && skb->dev->type == ARPHRD_ETHER))
                        goto drop;
                break;
        case TCA_MPLS_ACT_MAC_PUSH:
                if (skb_vlan_tag_present(skb)) {
                        if (__vlan_insert_inner_tag(skb, skb->vlan_proto,
                                                    skb_vlan_tag_get(skb),
                                                    ETH_HLEN) < 0)
                                goto drop;

                        skb->protocol = skb->vlan_proto;
                        __vlan_hwaccel_clear_tag(skb);
                }

                new_lse = tcf_mpls_get_lse(NULL, p, mac_len ||
                                           !eth_p_mpls(skb->protocol));

                if (skb_mpls_push(skb, new_lse, p->tcfm_proto, 0, false))
                        goto drop;
                break;
        case TCA_MPLS_ACT_MODIFY:
                if (!pskb_may_pull(skb,
                                   skb_network_offset(skb) + MPLS_HLEN))
                        goto drop;
                new_lse = tcf_mpls_get_lse(mpls_hdr(skb), p, false);
                if (skb_mpls_update_lse(skb, new_lse))
                        goto drop;
                break;
        case TCA_MPLS_ACT_DEC_TTL:
                if (skb_mpls_dec_ttl(skb))
                        goto drop;
                break;
        }

        if (skb_at_tc_ingress(skb))
                skb_pull_rcsum(skb, skb->mac_len);

        return p->action;

drop:
        qstats_drop_inc(this_cpu_ptr(m->common.cpu_qstats));
        return TC_ACT_SHOT;
}

static int valid_label(const struct nlattr *attr,
                       struct netlink_ext_ack *extack)
{
        const u32 *label = nla_data(attr);

        if (nla_len(attr) != sizeof(*label)) {
                NL_SET_ERR_MSG_MOD(extack, "Invalid MPLS label length");
                return -EINVAL;
        }

        if (*label & ~MPLS_LABEL_MASK || *label == MPLS_LABEL_IMPLNULL) {
                NL_SET_ERR_MSG_MOD(extack, "MPLS label out of range");
                return -EINVAL;
        }

        return 0;
}

static const struct nla_policy mpls_policy[TCA_MPLS_MAX + 1] = {
        [TCA_MPLS_PARMS]        = NLA_POLICY_EXACT_LEN(sizeof(struct tc_mpls)),
        [TCA_MPLS_PROTO]        = { .type = NLA_U16 },
        [TCA_MPLS_LABEL]        = NLA_POLICY_VALIDATE_FN(NLA_BINARY,
                                                         valid_label),
        [TCA_MPLS_TC]           = NLA_POLICY_RANGE(NLA_U8, 0, 7),
        [TCA_MPLS_TTL]          = NLA_POLICY_MIN(NLA_U8, 1),
        [TCA_MPLS_BOS]          = NLA_POLICY_RANGE(NLA_U8, 0, 1),
};

static int tcf_mpls_init(struct net *net, struct nlattr *nla,
                         struct nlattr *est, struct tc_action **a,
                         struct tcf_proto *tp, u32 flags,
                         struct netlink_ext_ack *extack)
{
        struct tc_action_net *tn = net_generic(net, act_mpls_ops.net_id);
        bool bind = flags & TCA_ACT_FLAGS_BIND;
        struct nlattr *tb[TCA_MPLS_MAX + 1];
        struct tcf_chain *goto_ch = NULL;
        struct tcf_mpls_params *p;
        struct tc_mpls *parm;
        bool exists = false;
        struct tcf_mpls *m;
        int ret = 0, err;
        u8 mpls_ttl = 0;
        u32 index;

        if (!nla) {
                NL_SET_ERR_MSG_MOD(extack, "Missing netlink attributes");
                return -EINVAL;
        }

        err = nla_parse_nested(tb, TCA_MPLS_MAX, nla, mpls_policy, extack);
        if (err < 0)
                return err;

        if (!tb[TCA_MPLS_PARMS]) {
                NL_SET_ERR_MSG_MOD(extack, "No MPLS params");
                return -EINVAL;
        }
        parm = nla_data(tb[TCA_MPLS_PARMS]);
        index = parm->index;

        err = tcf_idr_check_alloc(tn, &index, a, bind);
        if (err < 0)
                return err;
        exists = err;
        if (exists && bind)
                return ACT_P_BOUND;

        if (!exists) {
                ret = tcf_idr_create(tn, index, est, a, &act_mpls_ops, bind,
                                     true, flags);
                if (ret) {
                        tcf_idr_cleanup(tn, index);
                        return ret;
                }

                ret = ACT_P_CREATED;
        } else if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
                tcf_idr_release(*a, bind);
                return -EEXIST;
        }

        /* Verify parameters against action type. */
        switch (parm->m_action) {
        case TCA_MPLS_ACT_POP:
                if (!tb[TCA_MPLS_PROTO]) {
                        NL_SET_ERR_MSG_MOD(extack, "Protocol must be set for MPLS pop");
                        err = -EINVAL;
                        goto release_idr;
                }
                if (!eth_proto_is_802_3(nla_get_be16(tb[TCA_MPLS_PROTO]))) {
                        NL_SET_ERR_MSG_MOD(extack, "Invalid protocol type for MPLS pop");
                        err = -EINVAL;
                        goto release_idr;
                }
                if (tb[TCA_MPLS_LABEL] || tb[TCA_MPLS_TTL] || tb[TCA_MPLS_TC] ||
                    tb[TCA_MPLS_BOS]) {
                        NL_SET_ERR_MSG_MOD(extack, "Label, TTL, TC or BOS cannot be used with MPLS pop");
                        err = -EINVAL;
                        goto release_idr;
                }
                break;
        case TCA_MPLS_ACT_DEC_TTL:
                if (tb[TCA_MPLS_PROTO] || tb[TCA_MPLS_LABEL] ||
                    tb[TCA_MPLS_TTL] || tb[TCA_MPLS_TC] || tb[TCA_MPLS_BOS]) {
                        NL_SET_ERR_MSG_MOD(extack, "Label, TTL, TC, BOS or protocol cannot be used with MPLS dec_ttl");
                        err = -EINVAL;
                        goto release_idr;
                }
                break;
        case TCA_MPLS_ACT_PUSH:
        case TCA_MPLS_ACT_MAC_PUSH:
                if (!tb[TCA_MPLS_LABEL]) {
                        NL_SET_ERR_MSG_MOD(extack, "Label is required for MPLS push");
                        err = -EINVAL;
                        goto release_idr;
                }
                if (tb[TCA_MPLS_PROTO] &&
                    !eth_p_mpls(nla_get_be16(tb[TCA_MPLS_PROTO]))) {
                        NL_SET_ERR_MSG_MOD(extack, "Protocol must be an MPLS type for MPLS push");
                        err = -EPROTONOSUPPORT;
                        goto release_idr;
                }
                /* Push needs a TTL - if not specified, set a default value. */
                if (!tb[TCA_MPLS_TTL]) {
#if IS_ENABLED(CONFIG_MPLS)
                        mpls_ttl = net->mpls.default_ttl ?
                                   net->mpls.default_ttl : ACT_MPLS_TTL_DEFAULT;
#else
                        mpls_ttl = ACT_MPLS_TTL_DEFAULT;
#endif
                }
                break;
        case TCA_MPLS_ACT_MODIFY:
                if (tb[TCA_MPLS_PROTO]) {
                        NL_SET_ERR_MSG_MOD(extack, "Protocol cannot be used with MPLS modify");
                        err = -EINVAL;
                        goto release_idr;
                }
                break;
        default:
                NL_SET_ERR_MSG_MOD(extack, "Unknown MPLS action");
                err = -EINVAL;
                goto release_idr;
        }

        err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
        if (err < 0)
                goto release_idr;

        m = to_mpls(*a);

        p = kzalloc_obj(*p);
        if (!p) {
                err = -ENOMEM;
                goto put_chain;
        }

        p->tcfm_action = parm->m_action;
        p->tcfm_label = nla_get_u32_default(tb[TCA_MPLS_LABEL],
                                            ACT_MPLS_LABEL_NOT_SET);
        p->tcfm_tc = nla_get_u8_default(tb[TCA_MPLS_TC], ACT_MPLS_TC_NOT_SET);
        p->tcfm_ttl = nla_get_u8_default(tb[TCA_MPLS_TTL], mpls_ttl);
        p->tcfm_bos = nla_get_u8_default(tb[TCA_MPLS_BOS],
                                         ACT_MPLS_BOS_NOT_SET);
        p->tcfm_proto = nla_get_be16_default(tb[TCA_MPLS_PROTO],
                                             htons(ETH_P_MPLS_UC));
        p->action = parm->action;

        spin_lock_bh(&m->tcf_lock);
        goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
        p = rcu_replace_pointer(m->mpls_p, p, lockdep_is_held(&m->tcf_lock));
        spin_unlock_bh(&m->tcf_lock);

        if (goto_ch)
                tcf_chain_put_by_act(goto_ch);
        if (p)
                kfree_rcu(p, rcu);

        return ret;
put_chain:
        if (goto_ch)
                tcf_chain_put_by_act(goto_ch);
release_idr:
        tcf_idr_release(*a, bind);
        return err;
}

static void tcf_mpls_cleanup(struct tc_action *a)
{
        struct tcf_mpls *m = to_mpls(a);
        struct tcf_mpls_params *p;

        p = rcu_dereference_protected(m->mpls_p, 1);
        if (p)
                kfree_rcu(p, rcu);
}

static int tcf_mpls_dump(struct sk_buff *skb, struct tc_action *a,
                         int bind, int ref)
{
        unsigned char *b = skb_tail_pointer(skb);
        const struct tcf_mpls *m = to_mpls(a);
        const struct tcf_mpls_params *p;
        struct tc_mpls opt = {
                .index    = m->tcf_index,
                .refcnt   = refcount_read(&m->tcf_refcnt) - ref,
                .bindcnt  = atomic_read(&m->tcf_bindcnt) - bind,
        };
        struct tcf_t t;

        rcu_read_lock();
        p = rcu_dereference(m->mpls_p);
        opt.m_action = p->tcfm_action;
        opt.action = p->action;

        if (nla_put(skb, TCA_MPLS_PARMS, sizeof(opt), &opt))
                goto nla_put_failure;

        if (p->tcfm_label != ACT_MPLS_LABEL_NOT_SET &&
            nla_put_u32(skb, TCA_MPLS_LABEL, p->tcfm_label))
                goto nla_put_failure;

        if (p->tcfm_tc != ACT_MPLS_TC_NOT_SET &&
            nla_put_u8(skb, TCA_MPLS_TC, p->tcfm_tc))
                goto nla_put_failure;

        if (p->tcfm_ttl && nla_put_u8(skb, TCA_MPLS_TTL, p->tcfm_ttl))
                goto nla_put_failure;

        if (p->tcfm_bos != ACT_MPLS_BOS_NOT_SET &&
            nla_put_u8(skb, TCA_MPLS_BOS, p->tcfm_bos))
                goto nla_put_failure;

        if (nla_put_be16(skb, TCA_MPLS_PROTO, p->tcfm_proto))
                goto nla_put_failure;

        tcf_tm_dump(&t, &m->tcf_tm);

        if (nla_put_64bit(skb, TCA_MPLS_TM, sizeof(t), &t, TCA_MPLS_PAD))
                goto nla_put_failure;

        rcu_read_unlock();

        return skb->len;

nla_put_failure:
        rcu_read_unlock();
        nlmsg_trim(skb, b);
        return -EMSGSIZE;
}

static int tcf_mpls_offload_act_setup(struct tc_action *act, void *entry_data,
                                      u32 *index_inc, bool bind,
                                      struct netlink_ext_ack *extack)
{
        if (bind) {
                struct flow_action_entry *entry = entry_data;

                switch (tcf_mpls_action(act)) {
                case TCA_MPLS_ACT_PUSH:
                        entry->id = FLOW_ACTION_MPLS_PUSH;
                        entry->mpls_push.proto = tcf_mpls_proto(act);
                        entry->mpls_push.label = tcf_mpls_label(act);
                        entry->mpls_push.tc = tcf_mpls_tc(act);
                        entry->mpls_push.bos = tcf_mpls_bos(act);
                        entry->mpls_push.ttl = tcf_mpls_ttl(act);
                        break;
                case TCA_MPLS_ACT_POP:
                        entry->id = FLOW_ACTION_MPLS_POP;
                        entry->mpls_pop.proto = tcf_mpls_proto(act);
                        break;
                case TCA_MPLS_ACT_MODIFY:
                        entry->id = FLOW_ACTION_MPLS_MANGLE;
                        entry->mpls_mangle.label = tcf_mpls_label(act);
                        entry->mpls_mangle.tc = tcf_mpls_tc(act);
                        entry->mpls_mangle.bos = tcf_mpls_bos(act);
                        entry->mpls_mangle.ttl = tcf_mpls_ttl(act);
                        break;
                case TCA_MPLS_ACT_DEC_TTL:
                        NL_SET_ERR_MSG_MOD(extack, "Offload not supported when \"dec_ttl\" option is used");
                        return -EOPNOTSUPP;
                case TCA_MPLS_ACT_MAC_PUSH:
                        NL_SET_ERR_MSG_MOD(extack, "Offload not supported when \"mac_push\" option is used");
                        return -EOPNOTSUPP;
                default:
                        NL_SET_ERR_MSG_MOD(extack, "Unsupported MPLS mode offload");
                        return -EOPNOTSUPP;
                }
                *index_inc = 1;
        } else {
                struct flow_offload_action *fl_action = entry_data;

                switch (tcf_mpls_action(act)) {
                case TCA_MPLS_ACT_PUSH:
                        fl_action->id = FLOW_ACTION_MPLS_PUSH;
                        break;
                case TCA_MPLS_ACT_POP:
                        fl_action->id = FLOW_ACTION_MPLS_POP;
                        break;
                case TCA_MPLS_ACT_MODIFY:
                        fl_action->id = FLOW_ACTION_MPLS_MANGLE;
                        break;
                default:
                        return -EOPNOTSUPP;
                }
        }

        return 0;
}

static struct tc_action_ops act_mpls_ops = {
        .kind           =       "mpls",
        .id             =       TCA_ID_MPLS,
        .owner          =       THIS_MODULE,
        .act            =       tcf_mpls_act,
        .dump           =       tcf_mpls_dump,
        .init           =       tcf_mpls_init,
        .cleanup        =       tcf_mpls_cleanup,
        .offload_act_setup =    tcf_mpls_offload_act_setup,
        .size           =       sizeof(struct tcf_mpls),
};
MODULE_ALIAS_NET_ACT("mpls");

static __net_init int mpls_init_net(struct net *net)
{
        struct tc_action_net *tn = net_generic(net, act_mpls_ops.net_id);

        return tc_action_net_init(net, tn, &act_mpls_ops);
}

static void __net_exit mpls_exit_net(struct list_head *net_list)
{
        tc_action_net_exit(net_list, act_mpls_ops.net_id);
}

static struct pernet_operations mpls_net_ops = {
        .init = mpls_init_net,
        .exit_batch = mpls_exit_net,
        .id   = &act_mpls_ops.net_id,
        .size = sizeof(struct tc_action_net),
};

static int __init mpls_init_module(void)
{
        return tcf_register_action(&act_mpls_ops, &mpls_net_ops);
}

static void __exit mpls_cleanup_module(void)
{
        tcf_unregister_action(&act_mpls_ops, &mpls_net_ops);
}

module_init(mpls_init_module);
module_exit(mpls_cleanup_module);

MODULE_SOFTDEP("post: mpls_gso");
MODULE_AUTHOR("Netronome Systems <oss-drivers@netronome.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MPLS manipulation actions");