// SPDX-License-Identifier: GPL-2.0
/*
 * IPv6 Address Label subsystem
 * for the IPv6 "Default" Source Address Selection
 *
 * Copyright (C)2007 USAGI/WIDE Project
 */
/*
 * Author:
 *      YOSHIFUJI Hideaki @ USAGI/WIDE Project <yoshfuji@linux-ipv6.org>
 */

#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/in6.h>
#include <linux/slab.h>
#include <net/addrconf.h>
#include <linux/if_addrlabel.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>

/*
 * Policy Table
 */
struct ip6addrlbl_entry {
        struct in6_addr prefix;
        int prefixlen;
        int ifindex;
        int addrtype;
        u32 label;
        struct hlist_node list;
        struct rcu_head rcu;
};

/*
 * Default policy table (RFC6724 + extensions)
 *
 * prefix               addr_type       label
 * -------------------------------------------------------------------------
 * ::1/128              LOOPBACK        0
 * ::/0                 N/A             1
 * 2002::/16            N/A             2
 * ::/96                COMPATv4        3
 * ::ffff:0:0/96        V4MAPPED        4
 * fc00::/7             N/A             5               ULA (RFC 4193)
 * 2001::/32            N/A             6               Teredo (RFC 4380)
 * 2001:10::/28         N/A             7               ORCHID (RFC 4843)
 * fec0::/10            N/A             11              Site-local
 *                                                      (deprecated by RFC3879)
 * 3ffe::/16            N/A             12              6bone
 *
 * Note: 0xffffffff is used if we do not have any policies.
 * Note: Labels for ULA and 6to4 are different from labels listed in RFC6724.
 */

#define IPV6_ADDR_LABEL_DEFAULT 0xffffffffUL

static const __net_initconst struct ip6addrlbl_init_table
{
        const struct in6_addr *prefix;
        int prefixlen;
        u32 label;
} ip6addrlbl_init_table[] = {
        {       /* ::/0 */
                .prefix = &in6addr_any,
                .label = 1,
        }, {    /* fc00::/7 */
                .prefix = &(struct in6_addr){ { { 0xfc } } } ,
                .prefixlen = 7,
                .label = 5,
        }, {    /* fec0::/10 */
                .prefix = &(struct in6_addr){ { { 0xfe, 0xc0 } } },
                .prefixlen = 10,
                .label = 11,
        }, {    /* 2002::/16 */
                .prefix = &(struct in6_addr){ { { 0x20, 0x02 } } },
                .prefixlen = 16,
                .label = 2,
        }, {    /* 3ffe::/16 */
                .prefix = &(struct in6_addr){ { { 0x3f, 0xfe } } },
                .prefixlen = 16,
                .label = 12,
        }, {    /* 2001::/32 */
                .prefix = &(struct in6_addr){ { { 0x20, 0x01 } } },
                .prefixlen = 32,
                .label = 6,
        }, {    /* 2001:10::/28 */
                .prefix = &(struct in6_addr){ { { 0x20, 0x01, 0x00, 0x10 } } },
                .prefixlen = 28,
                .label = 7,
        }, {    /* ::ffff:0:0 */
                .prefix = &(struct in6_addr){ { { [10] = 0xff, [11] = 0xff } } },
                .prefixlen = 96,
                .label = 4,
        }, {    /* ::/96 */
                .prefix = &in6addr_any,
                .prefixlen = 96,
                .label = 3,
        }, {    /* ::1/128 */
                .prefix = &in6addr_loopback,
                .prefixlen = 128,
                .label = 0,
        }
};

/* Find label */
static bool __ip6addrlbl_match(const struct ip6addrlbl_entry *p,
                               const struct in6_addr *addr,
                               int addrtype, int ifindex)
{
        if (p->ifindex && p->ifindex != ifindex)
                return false;
        if (p->addrtype && p->addrtype != addrtype)
                return false;
        if (!ipv6_prefix_equal(addr, &p->prefix, p->prefixlen))
                return false;
        return true;
}

static struct ip6addrlbl_entry *__ipv6_addr_label(struct net *net,
                                                  const struct in6_addr *addr,
                                                  int type, int ifindex)
{
        struct ip6addrlbl_entry *p;

        hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
                if (__ip6addrlbl_match(p, addr, type, ifindex))
                        return p;
        }
        return NULL;
}

u32 ipv6_addr_label(struct net *net,
                    const struct in6_addr *addr, int type, int ifindex)
{
        u32 label;
        struct ip6addrlbl_entry *p;

        type &= IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK;

        rcu_read_lock();
        p = __ipv6_addr_label(net, addr, type, ifindex);
        label = p ? p->label : IPV6_ADDR_LABEL_DEFAULT;
        rcu_read_unlock();

        net_dbg_ratelimited("%s(addr=%pI6, type=%d, ifindex=%d) => %08x\n", __func__, addr, type,
                            ifindex, label);

        return label;
}

/* allocate one entry */
static struct ip6addrlbl_entry *ip6addrlbl_alloc(const struct in6_addr *prefix,
                                                 int prefixlen, int ifindex,
                                                 u32 label)
{
        struct ip6addrlbl_entry *newp;
        int addrtype;

        net_dbg_ratelimited("%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u)\n", __func__,
                            prefix, prefixlen, ifindex, (unsigned int)label);

        addrtype = ipv6_addr_type(prefix) & (IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK);

        switch (addrtype) {
        case IPV6_ADDR_MAPPED:
                if (prefixlen > 96)
                        return ERR_PTR(-EINVAL);
                if (prefixlen < 96)
                        addrtype = 0;
                break;
        case IPV6_ADDR_COMPATv4:
                if (prefixlen != 96)
                        addrtype = 0;
                break;
        case IPV6_ADDR_LOOPBACK:
                if (prefixlen != 128)
                        addrtype = 0;
                break;
        }

        newp = kmalloc_obj(*newp);
        if (!newp)
                return ERR_PTR(-ENOMEM);

        ipv6_addr_prefix(&newp->prefix, prefix, prefixlen);
        newp->prefixlen = prefixlen;
        newp->ifindex = ifindex;
        newp->addrtype = addrtype;
        newp->label = label;
        INIT_HLIST_NODE(&newp->list);
        return newp;
}

/* add a label */
static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp,
                            int replace)
{
        struct ip6addrlbl_entry *last = NULL, *p = NULL;
        struct hlist_node *n;
        int ret = 0;

        net_dbg_ratelimited("%s(newp=%p, replace=%d)\n", __func__, newp, replace);

        hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
                if (p->prefixlen == newp->prefixlen &&
                    p->ifindex == newp->ifindex &&
                    ipv6_addr_equal(&p->prefix, &newp->prefix)) {
                        if (!replace) {
                                ret = -EEXIST;
                                goto out;
                        }
                        hlist_replace_rcu(&p->list, &newp->list);
                        kfree_rcu(p, rcu);
                        goto out;
                } else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
                           (p->prefixlen < newp->prefixlen)) {
                        hlist_add_before_rcu(&newp->list, &p->list);
                        goto out;
                }
                last = p;
        }
        if (last)
                hlist_add_behind_rcu(&newp->list, &last->list);
        else
                hlist_add_head_rcu(&newp->list, &net->ipv6.ip6addrlbl_table.head);
out:
        if (!ret)
                WRITE_ONCE(net->ipv6.ip6addrlbl_table.seq,
                           net->ipv6.ip6addrlbl_table.seq + 1);
        return ret;
}

/* add a label */
static int ip6addrlbl_add(struct net *net,
                          const struct in6_addr *prefix, int prefixlen,
                          int ifindex, u32 label, int replace)
{
        struct ip6addrlbl_entry *newp;
        int ret = 0;

        net_dbg_ratelimited("%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u, replace=%d)\n",
                            __func__, prefix, prefixlen, ifindex, (unsigned int)label, replace);

        newp = ip6addrlbl_alloc(prefix, prefixlen, ifindex, label);
        if (IS_ERR(newp))
                return PTR_ERR(newp);
        spin_lock(&net->ipv6.ip6addrlbl_table.lock);
        ret = __ip6addrlbl_add(net, newp, replace);
        spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
        if (ret)
                kfree(newp);
        return ret;
}

/* remove a label */
static int __ip6addrlbl_del(struct net *net,
                            const struct in6_addr *prefix, int prefixlen,
                            int ifindex)
{
        struct ip6addrlbl_entry *p = NULL;
        struct hlist_node *n;
        int ret = -ESRCH;

        net_dbg_ratelimited("%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n", __func__, prefix,
                            prefixlen, ifindex);

        hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
                if (p->prefixlen == prefixlen &&
                    p->ifindex == ifindex &&
                    ipv6_addr_equal(&p->prefix, prefix)) {
                        hlist_del_rcu(&p->list);
                        kfree_rcu(p, rcu);
                        ret = 0;
                        break;
                }
        }
        return ret;
}

static int ip6addrlbl_del(struct net *net,
                          const struct in6_addr *prefix, int prefixlen,
                          int ifindex)
{
        struct in6_addr prefix_buf;
        int ret;

        net_dbg_ratelimited("%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n", __func__, prefix,
                            prefixlen, ifindex);

        ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
        spin_lock(&net->ipv6.ip6addrlbl_table.lock);
        ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);
        spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
        return ret;
}

/* add default label */
static int __net_init ip6addrlbl_net_init(struct net *net)
{
        struct ip6addrlbl_entry *p = NULL;
        struct hlist_node *n;
        int err;
        int i;

        spin_lock_init(&net->ipv6.ip6addrlbl_table.lock);
        INIT_HLIST_HEAD(&net->ipv6.ip6addrlbl_table.head);

        for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {
                err = ip6addrlbl_add(net,
                                     ip6addrlbl_init_table[i].prefix,
                                     ip6addrlbl_init_table[i].prefixlen,
                                     0,
                                     ip6addrlbl_init_table[i].label, 0);
                if (err)
                        goto err_ip6addrlbl_add;
        }
        return 0;

err_ip6addrlbl_add:
        hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
                hlist_del_rcu(&p->list);
                kfree_rcu(p, rcu);
        }
        return err;
}

static void __net_exit ip6addrlbl_net_exit(struct net *net)
{
        struct ip6addrlbl_entry *p = NULL;
        struct hlist_node *n;

        /* Remove all labels belonging to the exiting net */
        spin_lock(&net->ipv6.ip6addrlbl_table.lock);
        hlist_for_each_entry_safe(p, n, &net->ipv6.ip6addrlbl_table.head, list) {
                hlist_del_rcu(&p->list);
                kfree_rcu(p, rcu);
        }
        spin_unlock(&net->ipv6.ip6addrlbl_table.lock);
}

static struct pernet_operations ipv6_addr_label_ops = {
        .init = ip6addrlbl_net_init,
        .exit = ip6addrlbl_net_exit,
};

int __init ipv6_addr_label_init(void)
{
        return register_pernet_subsys(&ipv6_addr_label_ops);
}

void ipv6_addr_label_cleanup(void)
{
        unregister_pernet_subsys(&ipv6_addr_label_ops);
}

static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
        [IFAL_ADDRESS]          = { .len = sizeof(struct in6_addr), },
        [IFAL_LABEL]            = { .len = sizeof(u32), },
};

static bool addrlbl_ifindex_exists(struct net *net, int ifindex)
{

        struct net_device *dev;

        rcu_read_lock();
        dev = dev_get_by_index_rcu(net, ifindex);
        rcu_read_unlock();

        return dev != NULL;
}

static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
                             struct netlink_ext_ack *extack)
{
        struct net *net = sock_net(skb->sk);
        struct ifaddrlblmsg *ifal;
        struct nlattr *tb[IFAL_MAX+1];
        struct in6_addr *pfx;
        u32 label;
        int err = 0;

        err = nlmsg_parse_deprecated(nlh, sizeof(*ifal), tb, IFAL_MAX,
                                     ifal_policy, extack);
        if (err < 0)
                return err;

        ifal = nlmsg_data(nlh);

        if (ifal->ifal_family != AF_INET6 ||
            ifal->ifal_prefixlen > 128)
                return -EINVAL;

        if (!tb[IFAL_ADDRESS])
                return -EINVAL;
        pfx = nla_data(tb[IFAL_ADDRESS]);

        if (!tb[IFAL_LABEL])
                return -EINVAL;
        label = nla_get_u32(tb[IFAL_LABEL]);
        if (label == IPV6_ADDR_LABEL_DEFAULT)
                return -EINVAL;

        switch (nlh->nlmsg_type) {
        case RTM_NEWADDRLABEL:
                if (ifal->ifal_index &&
                    !addrlbl_ifindex_exists(net, ifal->ifal_index))
                        return -EINVAL;

                err = ip6addrlbl_add(net, pfx, ifal->ifal_prefixlen,
                                     ifal->ifal_index, label,
                                     nlh->nlmsg_flags & NLM_F_REPLACE);
                break;
        case RTM_DELADDRLABEL:
                err = ip6addrlbl_del(net, pfx, ifal->ifal_prefixlen,
                                     ifal->ifal_index);
                break;
        default:
                err = -EOPNOTSUPP;
        }
        return err;
}

static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
                              int prefixlen, int ifindex, u32 lseq)
{
        struct ifaddrlblmsg *ifal = nlmsg_data(nlh);
        ifal->ifal_family = AF_INET6;
        ifal->__ifal_reserved = 0;
        ifal->ifal_prefixlen = prefixlen;
        ifal->ifal_flags = 0;
        ifal->ifal_index = ifindex;
        ifal->ifal_seq = lseq;
};

static int ip6addrlbl_fill(struct sk_buff *skb,
                           const struct ip6addrlbl_entry *p,
                           u32 lseq,
                           u32 portid, u32 seq, int event,
                           unsigned int flags)
{
        struct nlmsghdr *nlh = nlmsg_put(skb, portid, seq, event,
                                         sizeof(struct ifaddrlblmsg), flags);
        if (!nlh)
                return -EMSGSIZE;

        ip6addrlbl_putmsg(nlh, p->prefixlen, p->ifindex, lseq);

        if (nla_put_in6_addr(skb, IFAL_ADDRESS, &p->prefix) < 0 ||
            nla_put_u32(skb, IFAL_LABEL, p->label) < 0) {
                nlmsg_cancel(skb, nlh);
                return -EMSGSIZE;
        }

        nlmsg_end(skb, nlh);
        return 0;
}

static int ip6addrlbl_valid_dump_req(const struct nlmsghdr *nlh,
                                     struct netlink_ext_ack *extack)
{
        struct ifaddrlblmsg *ifal;

        ifal = nlmsg_payload(nlh, sizeof(*ifal));
        if (!ifal) {
                NL_SET_ERR_MSG_MOD(extack, "Invalid header for address label dump request");
                return -EINVAL;
        }

        if (ifal->__ifal_reserved || ifal->ifal_prefixlen ||
            ifal->ifal_flags || ifal->ifal_index || ifal->ifal_seq) {
                NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for address label dump request");
                return -EINVAL;
        }

        if (nlmsg_attrlen(nlh, sizeof(*ifal))) {
                NL_SET_ERR_MSG_MOD(extack, "Invalid data after header for address label dump request");
                return -EINVAL;
        }

        return 0;
}

static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
        const struct nlmsghdr *nlh = cb->nlh;
        struct net *net = sock_net(skb->sk);
        struct ip6addrlbl_entry *p;
        int idx = 0, s_idx = cb->args[0];
        int err = 0;
        u32 lseq;

        if (cb->strict_check) {
                err = ip6addrlbl_valid_dump_req(nlh, cb->extack);
                if (err < 0)
                        return err;
        }

        rcu_read_lock();
        lseq = READ_ONCE(net->ipv6.ip6addrlbl_table.seq);
        hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
                if (idx >= s_idx) {
                        err = ip6addrlbl_fill(skb, p,
                                              lseq,
                                              NETLINK_CB(cb->skb).portid,
                                              nlh->nlmsg_seq,
                                              RTM_NEWADDRLABEL,
                                              NLM_F_MULTI);
                        if (err < 0)
                                break;
                }
                idx++;
        }
        rcu_read_unlock();
        cb->args[0] = idx;
        return err;
}

static inline int ip6addrlbl_msgsize(void)
{
        return NLMSG_ALIGN(sizeof(struct ifaddrlblmsg))
                + nla_total_size(16)    /* IFAL_ADDRESS */
                + nla_total_size(4);    /* IFAL_LABEL */
}

static int ip6addrlbl_valid_get_req(struct sk_buff *skb,
                                    const struct nlmsghdr *nlh,
                                    struct nlattr **tb,
                                    struct netlink_ext_ack *extack)
{
        struct ifaddrlblmsg *ifal;
        int i, err;

        ifal = nlmsg_payload(nlh, sizeof(*ifal));
        if (!ifal) {
                NL_SET_ERR_MSG_MOD(extack, "Invalid header for addrlabel get request");
                return -EINVAL;
        }

        if (!netlink_strict_get_check(skb))
                return nlmsg_parse_deprecated(nlh, sizeof(*ifal), tb,
                                              IFAL_MAX, ifal_policy, extack);

        if (ifal->__ifal_reserved || ifal->ifal_flags || ifal->ifal_seq) {
                NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for addrlabel get request");
                return -EINVAL;
        }

        err = nlmsg_parse_deprecated_strict(nlh, sizeof(*ifal), tb, IFAL_MAX,
                                            ifal_policy, extack);
        if (err)
                return err;

        for (i = 0; i <= IFAL_MAX; i++) {
                if (!tb[i])
                        continue;

                switch (i) {
                case IFAL_ADDRESS:
                        break;
                default:
                        NL_SET_ERR_MSG_MOD(extack, "Unsupported attribute in addrlabel get request");
                        return -EINVAL;
                }
        }

        return 0;
}

static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                          struct netlink_ext_ack *extack)
{
        struct net *net = sock_net(in_skb->sk);
        struct ifaddrlblmsg *ifal;
        struct nlattr *tb[IFAL_MAX+1];
        struct in6_addr *addr;
        u32 lseq;
        int err = 0;
        struct ip6addrlbl_entry *p;
        struct sk_buff *skb;

        err = ip6addrlbl_valid_get_req(in_skb, nlh, tb, extack);
        if (err < 0)
                return err;

        ifal = nlmsg_data(nlh);

        if (ifal->ifal_family != AF_INET6 ||
            ifal->ifal_prefixlen != 128)
                return -EINVAL;

        if (ifal->ifal_index &&
            !addrlbl_ifindex_exists(net, ifal->ifal_index))
                return -EINVAL;

        if (!tb[IFAL_ADDRESS])
                return -EINVAL;
        addr = nla_data(tb[IFAL_ADDRESS]);

        skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL);
        if (!skb)
                return -ENOBUFS;

        err = -ESRCH;

        rcu_read_lock();
        p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
        lseq = READ_ONCE(net->ipv6.ip6addrlbl_table.seq);
        if (p)
                err = ip6addrlbl_fill(skb, p, lseq,
                                      NETLINK_CB(in_skb).portid,
                                      nlh->nlmsg_seq,
                                      RTM_NEWADDRLABEL, 0);
        rcu_read_unlock();

        if (err < 0) {
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(skb);
        } else {
                err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
        }
        return err;
}

static const struct rtnl_msg_handler ipv6_adddr_label_rtnl_msg_handlers[] __initconst_or_module = {
        {.owner = THIS_MODULE, .protocol = PF_INET6, .msgtype = RTM_NEWADDRLABEL,
         .doit = ip6addrlbl_newdel, .flags = RTNL_FLAG_DOIT_UNLOCKED},
        {.owner = THIS_MODULE, .protocol = PF_INET6, .msgtype = RTM_DELADDRLABEL,
         .doit = ip6addrlbl_newdel, .flags = RTNL_FLAG_DOIT_UNLOCKED},
        {.owner = THIS_MODULE, .protocol = PF_INET6, .msgtype = RTM_GETADDRLABEL,
         .doit = ip6addrlbl_get, .dumpit = ip6addrlbl_dump,
         .flags = RTNL_FLAG_DOIT_UNLOCKED | RTNL_FLAG_DUMP_UNLOCKED},
};

int __init ipv6_addr_label_rtnl_register(void)
{
        return rtnl_register_many(ipv6_adddr_label_rtnl_msg_handlers);
}