// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/static_key.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_log.h>
#include <net/netfilter/nft_meta.h>

#ifdef CONFIG_MITIGATION_RETPOLINE
static struct static_key_false nf_tables_skip_direct_calls;

static inline bool nf_skip_indirect_calls(void)
{
        return static_branch_likely(&nf_tables_skip_direct_calls);
}

static inline void __init nf_skip_indirect_calls_enable(void)
{
        if (!cpu_feature_enabled(X86_FEATURE_RETPOLINE))
                static_branch_enable(&nf_tables_skip_direct_calls);
}
#else
static inline void nf_skip_indirect_calls_enable(void) { }
#endif /* CONFIG_MITIGATION_RETPOLINE */

static noinline void __nft_trace_packet(const struct nft_pktinfo *pkt,
                                        const struct nft_verdict *verdict,
                                        const struct nft_rule_dp *rule,
                                        struct nft_traceinfo *info,
                                        enum nft_trace_types type)
{
        if (!info->trace || !info->nf_trace)
                return;

        info->type = type;

        nft_trace_notify(pkt, verdict, rule, info);
}

static inline void nft_trace_packet(const struct nft_pktinfo *pkt,
                                    struct nft_verdict *verdict,
                                    struct nft_traceinfo *info,
                                    const struct nft_rule_dp *rule,
                                    enum nft_trace_types type)
{
        if (static_branch_unlikely(&nft_trace_enabled)) {
                info->nf_trace = pkt->skb->nf_trace;
                __nft_trace_packet(pkt, verdict, rule, info, type);
        }
}

static inline void nft_trace_copy_nftrace(const struct nft_pktinfo *pkt,
                                          struct nft_traceinfo *info)
{
        if (static_branch_unlikely(&nft_trace_enabled))
                info->nf_trace = pkt->skb->nf_trace;
}

static void nft_bitwise_fast_eval(const struct nft_expr *expr,
                                  struct nft_regs *regs)
{
        const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
        u32 *src = &regs->data[priv->sreg];
        u32 *dst = &regs->data[priv->dreg];

        *dst = (*src & priv->mask) ^ priv->xor;
}

static void nft_cmp_fast_eval(const struct nft_expr *expr,
                              struct nft_regs *regs)
{
        const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);

        if (((regs->data[priv->sreg] & priv->mask) == priv->data) ^ priv->inv)
                return;
        regs->verdict.code = NFT_BREAK;
}

static void nft_cmp16_fast_eval(const struct nft_expr *expr,
                                struct nft_regs *regs)
{
        const struct nft_cmp16_fast_expr *priv = nft_expr_priv(expr);
        const u64 *reg_data = (const u64 *)&regs->data[priv->sreg];
        const u64 *mask = (const u64 *)&priv->mask;
        const u64 *data = (const u64 *)&priv->data;

        if (((reg_data[0] & mask[0]) == data[0] &&
            ((reg_data[1] & mask[1]) == data[1])) ^ priv->inv)
                return;
        regs->verdict.code = NFT_BREAK;
}

static noinline void __nft_trace_verdict(const struct nft_pktinfo *pkt,
                                         struct nft_traceinfo *info,
                                         const struct nft_rule_dp *rule,
                                         const struct nft_regs *regs)
{
        enum nft_trace_types type;

        switch (regs->verdict.code & NF_VERDICT_MASK) {
        case NFT_CONTINUE:
        case NFT_RETURN:
                type = NFT_TRACETYPE_RETURN;
                break;
        case NF_STOLEN:
                type = NFT_TRACETYPE_RULE;
                /* can't access skb->nf_trace; use copy */
                break;
        default:
                type = NFT_TRACETYPE_RULE;

                if (info->trace)
                        info->nf_trace = pkt->skb->nf_trace;
                break;
        }

        __nft_trace_packet(pkt, &regs->verdict, rule, info, type);
}

static inline void nft_trace_verdict(const struct nft_pktinfo *pkt,
                                     struct nft_traceinfo *info,
                                     const struct nft_rule_dp *rule,
                                     const struct nft_regs *regs)
{
        if (static_branch_unlikely(&nft_trace_enabled))
                __nft_trace_verdict(pkt, info, rule, regs);
}

static bool nft_payload_fast_eval(const struct nft_expr *expr,
                                  struct nft_regs *regs,
                                  const struct nft_pktinfo *pkt)
{
        const struct nft_payload *priv = nft_expr_priv(expr);
        const struct sk_buff *skb = pkt->skb;
        u32 *dest = &regs->data[priv->dreg];
        unsigned char *ptr;

        if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
                ptr = skb_network_header(skb);
        else {
                if (!(pkt->flags & NFT_PKTINFO_L4PROTO))
                        return false;
                ptr = skb->data + nft_thoff(pkt);
        }

        ptr += priv->offset;

        if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
                return false;

        *dest = 0;
        if (priv->len == 2)
                *(u16 *)dest = *(u16 *)ptr;
        else if (priv->len == 4)
                *(u32 *)dest = *(u32 *)ptr;
        else
                *(u8 *)dest = *(u8 *)ptr;
        return true;
}

DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);

static noinline void nft_update_chain_stats(const struct nft_chain *chain,
                                            const struct nft_pktinfo *pkt)
{
        struct nft_base_chain *base_chain;
        struct nft_stats __percpu *pstats;
        struct nft_stats *stats;

        base_chain = nft_base_chain(chain);

        pstats = READ_ONCE(base_chain->stats);
        if (pstats) {
                local_bh_disable();
                stats = this_cpu_ptr(pstats);
                u64_stats_update_begin(&stats->syncp);
                stats->pkts++;
                stats->bytes += pkt->skb->len;
                u64_stats_update_end(&stats->syncp);
                local_bh_enable();
        }
}

struct nft_jumpstack {
        const struct nft_rule_dp *rule;
};

static void expr_call_ops_eval(const struct nft_expr *expr,
                               struct nft_regs *regs,
                               struct nft_pktinfo *pkt)
{
#ifdef CONFIG_MITIGATION_RETPOLINE
        unsigned long e;

        if (nf_skip_indirect_calls())
                goto indirect_call;

        e = (unsigned long)expr->ops->eval;
#define X(e, fun) \
        do { if ((e) == (unsigned long)(fun)) \
                return fun(expr, regs, pkt); } while (0)

        X(e, nft_payload_eval);
        X(e, nft_cmp_eval);
        X(e, nft_counter_eval);
        X(e, nft_meta_get_eval);
        X(e, nft_lookup_eval);
#if IS_ENABLED(CONFIG_NFT_CT)
        X(e, nft_ct_get_fast_eval);
#endif
        X(e, nft_range_eval);
        X(e, nft_immediate_eval);
        X(e, nft_byteorder_eval);
        X(e, nft_dynset_eval);
        X(e, nft_rt_get_eval);
        X(e, nft_bitwise_eval);
        X(e, nft_objref_eval);
        X(e, nft_objref_map_eval);
#undef  X
indirect_call:
#endif /* CONFIG_MITIGATION_RETPOLINE */
        expr->ops->eval(expr, regs, pkt);
}

#define nft_rule_expr_first(rule)       (struct nft_expr *)&rule->data[0]
#define nft_rule_expr_next(expr)        ((void *)expr) + expr->ops->size
#define nft_rule_expr_last(rule)        (struct nft_expr *)&rule->data[rule->dlen]

#define nft_rule_dp_for_each_expr(expr, last, rule) \
        for ((expr) = nft_rule_expr_first(rule), (last) = nft_rule_expr_last(rule); \
             (expr) != (last); \
             (expr) = nft_rule_expr_next(expr))

unsigned int
nft_do_chain(struct nft_pktinfo *pkt, void *priv)
{
        const struct nft_chain *chain = priv, *basechain = chain;
        const struct net *net = nft_net(pkt);
        const struct nft_expr *expr, *last;
        const struct nft_rule_dp *rule;
        struct nft_regs regs;
        unsigned int stackptr = 0;
        struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
        bool genbit = READ_ONCE(net->nft.gencursor);
        struct nft_rule_blob *blob;
        struct nft_traceinfo info;

        info.trace = false;
        if (static_branch_unlikely(&nft_trace_enabled))
                nft_trace_init(&info, pkt, basechain);
do_chain:
        if (genbit)
                blob = rcu_dereference(chain->blob_gen_1);
        else
                blob = rcu_dereference(chain->blob_gen_0);

        rule = (struct nft_rule_dp *)blob->data;
next_rule:
        regs.verdict.code = NFT_CONTINUE;
        for (; !rule->is_last ; rule = nft_rule_next(rule)) {
                nft_rule_dp_for_each_expr(expr, last, rule) {
                        if (expr->ops == &nft_cmp_fast_ops)
                                nft_cmp_fast_eval(expr, &regs);
                        else if (expr->ops == &nft_cmp16_fast_ops)
                                nft_cmp16_fast_eval(expr, &regs);
                        else if (expr->ops == &nft_bitwise_fast_ops)
                                nft_bitwise_fast_eval(expr, &regs);
                        else if (expr->ops != &nft_payload_fast_ops ||
                                 !nft_payload_fast_eval(expr, &regs, pkt))
                                expr_call_ops_eval(expr, &regs, pkt);

                        if (regs.verdict.code != NFT_CONTINUE)
                                break;
                }

                switch (regs.verdict.code) {
                case NFT_BREAK:
                        regs.verdict.code = NFT_CONTINUE;
                        nft_trace_copy_nftrace(pkt, &info);
                        continue;
                case NFT_CONTINUE:
                        nft_trace_packet(pkt, &regs.verdict,  &info, rule,
                                         NFT_TRACETYPE_RULE);
                        continue;
                }
                break;
        }

        nft_trace_verdict(pkt, &info, rule, &regs);

        switch (regs.verdict.code & NF_VERDICT_MASK) {
        case NF_ACCEPT:
        case NF_QUEUE:
        case NF_STOLEN:
                return regs.verdict.code;
        case NF_DROP:
                return NF_DROP_REASON(pkt->skb, SKB_DROP_REASON_NETFILTER_DROP, EPERM);
        }

        switch (regs.verdict.code) {
        case NFT_JUMP:
                if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
                        return NF_DROP;
                jumpstack[stackptr].rule = nft_rule_next(rule);
                stackptr++;
                fallthrough;
        case NFT_GOTO:
                chain = regs.verdict.chain;
                goto do_chain;
        case NFT_CONTINUE:
        case NFT_RETURN:
                break;
        default:
                WARN_ON_ONCE(1);
        }

        if (stackptr > 0) {
                stackptr--;
                rule = jumpstack[stackptr].rule;
                goto next_rule;
        }

        nft_trace_packet(pkt, &regs.verdict, &info, NULL, NFT_TRACETYPE_POLICY);

        if (static_branch_unlikely(&nft_counters_enabled))
                nft_update_chain_stats(basechain, pkt);

        if (nft_base_chain(basechain)->policy == NF_DROP)
                return NF_DROP_REASON(pkt->skb, SKB_DROP_REASON_NETFILTER_DROP, EPERM);

        return nft_base_chain(basechain)->policy;
}
EXPORT_SYMBOL_GPL(nft_do_chain);

static struct nft_expr_type *nft_basic_types[] = {
        &nft_imm_type,
        &nft_cmp_type,
        &nft_lookup_type,
        &nft_bitwise_type,
        &nft_byteorder_type,
        &nft_payload_type,
        &nft_dynset_type,
        &nft_range_type,
        &nft_meta_type,
        &nft_rt_type,
        &nft_exthdr_type,
        &nft_last_type,
        &nft_counter_type,
        &nft_objref_type,
        &nft_inner_type,
};

static struct nft_object_type *nft_basic_objects[] = {
#ifdef CONFIG_NETWORK_SECMARK
        &nft_secmark_obj_type,
#endif
        &nft_counter_obj_type,
};

int __init nf_tables_core_module_init(void)
{
        int err, i, j = 0;

        nft_counter_init_seqcount();

        for (i = 0; i < ARRAY_SIZE(nft_basic_objects); i++) {
                err = nft_register_obj(nft_basic_objects[i]);
                if (err)
                        goto err;
        }

        for (j = 0; j < ARRAY_SIZE(nft_basic_types); j++) {
                err = nft_register_expr(nft_basic_types[j]);
                if (err)
                        goto err;
        }

        nf_skip_indirect_calls_enable();

        return 0;

err:
        while (j-- > 0)
                nft_unregister_expr(nft_basic_types[j]);

        while (i-- > 0)
                nft_unregister_obj(nft_basic_objects[i]);

        return err;
}

void nf_tables_core_module_exit(void)
{
        int i;

        i = ARRAY_SIZE(nft_basic_types);
        while (i-- > 0)
                nft_unregister_expr(nft_basic_types[i]);

        i = ARRAY_SIZE(nft_basic_objects);
        while (i-- > 0)
                nft_unregister_obj(nft_basic_objects[i]);
}