// SPDX-License-Identifier: GPL-2.0-or-later
/* Structure dynamic extension infrastructure
 * Copyright (C) 2004 Rusty Russell IBM Corporation
 * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
 * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>
 */
#include <linux/kernel.h>
#include <linux/kmemleak.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <net/netfilter/nf_conntrack_extend.h>

#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_acct.h>
#include <net/netfilter/nf_conntrack_seqadj.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/nf_conntrack_timestamp.h>
#include <net/netfilter/nf_conntrack_timeout.h>
#include <net/netfilter/nf_conntrack_labels.h>
#include <net/netfilter/nf_conntrack_synproxy.h>
#include <net/netfilter/nf_conntrack_act_ct.h>
#include <net/netfilter/nf_nat.h>

#define NF_CT_EXT_PREALLOC      128u /* conntrack events are on by default */

atomic_t nf_conntrack_ext_genid __read_mostly = ATOMIC_INIT(1);

static const u8 nf_ct_ext_type_len[NF_CT_EXT_NUM] = {
        [NF_CT_EXT_HELPER] = sizeof(struct nf_conn_help),
#if IS_ENABLED(CONFIG_NF_NAT)
        [NF_CT_EXT_NAT] = sizeof(struct nf_conn_nat),
#endif
        [NF_CT_EXT_SEQADJ] = sizeof(struct nf_conn_seqadj),
        [NF_CT_EXT_ACCT] = sizeof(struct nf_conn_acct),
#ifdef CONFIG_NF_CONNTRACK_EVENTS
        [NF_CT_EXT_ECACHE] = sizeof(struct nf_conntrack_ecache),
#endif
#ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
        [NF_CT_EXT_TSTAMP] = sizeof(struct nf_conn_tstamp),
#endif
#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
        [NF_CT_EXT_TIMEOUT] = sizeof(struct nf_conn_timeout),
#endif
#ifdef CONFIG_NF_CONNTRACK_LABELS
        [NF_CT_EXT_LABELS] = sizeof(struct nf_conn_labels),
#endif
#if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
        [NF_CT_EXT_SYNPROXY] = sizeof(struct nf_conn_synproxy),
#endif
#if IS_ENABLED(CONFIG_NET_ACT_CT)
        [NF_CT_EXT_ACT_CT] = sizeof(struct nf_conn_act_ct_ext),
#endif
};

static __always_inline unsigned int total_extension_size(void)
{
        /* remember to add new extensions below */
        BUILD_BUG_ON(NF_CT_EXT_NUM > 10);

        return sizeof(struct nf_ct_ext) +
               sizeof(struct nf_conn_help)
#if IS_ENABLED(CONFIG_NF_NAT)
                + sizeof(struct nf_conn_nat)
#endif
                + sizeof(struct nf_conn_seqadj)
                + sizeof(struct nf_conn_acct)
#ifdef CONFIG_NF_CONNTRACK_EVENTS
                + sizeof(struct nf_conntrack_ecache)
#endif
#ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
                + sizeof(struct nf_conn_tstamp)
#endif
#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
                + sizeof(struct nf_conn_timeout)
#endif
#ifdef CONFIG_NF_CONNTRACK_LABELS
                + sizeof(struct nf_conn_labels)
#endif
#if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
                + sizeof(struct nf_conn_synproxy)
#endif
#if IS_ENABLED(CONFIG_NET_ACT_CT)
                + sizeof(struct nf_conn_act_ct_ext)
#endif
        ;
}

void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
{
        unsigned int newlen, newoff, oldlen, alloc;
        struct nf_ct_ext *new;

        /* Conntrack must not be confirmed to avoid races on reallocation. */
        WARN_ON(nf_ct_is_confirmed(ct));

        /* struct nf_ct_ext uses u8 to store offsets/size */
        BUILD_BUG_ON(total_extension_size() > 255u);

        if (ct->ext) {
                const struct nf_ct_ext *old = ct->ext;

                if (__nf_ct_ext_exist(old, id))
                        return NULL;
                oldlen = old->len;
        } else {
                oldlen = sizeof(*new);
        }

        newoff = ALIGN(oldlen, __alignof__(struct nf_ct_ext));
        newlen = newoff + nf_ct_ext_type_len[id];

        alloc = max(newlen, NF_CT_EXT_PREALLOC);
        new = krealloc(ct->ext, alloc, gfp);
        if (!new)
                return NULL;

        if (!ct->ext) {
                memset(new->offset, 0, sizeof(new->offset));
                new->gen_id = atomic_read(&nf_conntrack_ext_genid);
        }

        new->offset[id] = newoff;
        new->len = newlen;
        memset((void *)new + newoff, 0, newlen - newoff);

        ct->ext = new;
        return (void *)new + newoff;
}
EXPORT_SYMBOL(nf_ct_ext_add);

/* Use nf_ct_ext_find wrapper. This is only useful for unconfirmed entries. */
void *__nf_ct_ext_find(const struct nf_ct_ext *ext, u8 id)
{
        unsigned int gen_id = atomic_read(&nf_conntrack_ext_genid);
        unsigned int this_id = READ_ONCE(ext->gen_id);

        if (!__nf_ct_ext_exist(ext, id))
                return NULL;

        if (this_id == 0 || ext->gen_id == gen_id)
                return (void *)ext + ext->offset[id];

        return NULL;
}
EXPORT_SYMBOL(__nf_ct_ext_find);

void nf_ct_ext_bump_genid(void)
{
        unsigned int value = atomic_inc_return(&nf_conntrack_ext_genid);

        if (value == UINT_MAX)
                atomic_set(&nf_conntrack_ext_genid, 1);

        msleep(HZ);
}