net/netfilter/nft_last.c

Source file repositories/reference/linux-study-clean/net/netfilter/nft_last.c

File Facts

System
Linux kernel
Corpus path
net/netfilter/nft_last.c
Extension
.c
Size
3273 bytes
Lines
138
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: implementation source
Status
source implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Dependency Surface

Detected Declarations

Annotated Snippet

struct nft_last {
	unsigned long	jiffies;
	unsigned int	set;
};

struct nft_last_priv {
	struct nft_last	*last;
};

static const struct nla_policy nft_last_policy[NFTA_LAST_MAX + 1] = {
	[NFTA_LAST_SET] = { .type = NLA_U32 },
	[NFTA_LAST_MSECS] = { .type = NLA_U64 },
};

static int nft_last_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
			 const struct nlattr * const tb[])
{
	struct nft_last_priv *priv = nft_expr_priv(expr);
	struct nft_last *last;
	u64 last_jiffies;
	int err;

	last = kzalloc_obj(*last, GFP_KERNEL_ACCOUNT);
	if (!last)
		return -ENOMEM;

	if (tb[NFTA_LAST_SET])
		last->set = ntohl(nla_get_be32(tb[NFTA_LAST_SET]));

	if (last->set && tb[NFTA_LAST_MSECS]) {
		err = nf_msecs_to_jiffies64(tb[NFTA_LAST_MSECS], &last_jiffies);
		if (err < 0)
			goto err;

		last->jiffies = jiffies - (unsigned long)last_jiffies;
	}
	priv->last = last;

	return 0;
err:
	kfree(last);

	return err;
}

static void nft_last_eval(const struct nft_expr *expr,
			  struct nft_regs *regs, const struct nft_pktinfo *pkt)
{
	struct nft_last_priv *priv = nft_expr_priv(expr);
	struct nft_last *last = priv->last;

	if (READ_ONCE(last->jiffies) != jiffies)
		WRITE_ONCE(last->jiffies, jiffies);
	if (READ_ONCE(last->set) == 0)
		WRITE_ONCE(last->set, 1);
}

static int nft_last_dump(struct sk_buff *skb,
			 const struct nft_expr *expr, bool reset)
{
	struct nft_last_priv *priv = nft_expr_priv(expr);
	struct nft_last *last = priv->last;
	unsigned long last_jiffies = READ_ONCE(last->jiffies);
	u32 last_set = READ_ONCE(last->set);
	__be64 msecs;

	if (time_before(jiffies, last_jiffies)) {
		WRITE_ONCE(last->set, 0);
		last_set = 0;
	}

	if (last_set)
		msecs = nf_jiffies64_to_msecs(jiffies - last_jiffies);
	else
		msecs = 0;

	if (nla_put_be32(skb, NFTA_LAST_SET, htonl(last_set)) ||
	    nla_put_be64(skb, NFTA_LAST_MSECS, msecs, NFTA_LAST_PAD))
		goto nla_put_failure;

	return 0;

nla_put_failure:
	return -1;
}

static void nft_last_destroy(const struct nft_ctx *ctx,
			     const struct nft_expr *expr)
{
	struct nft_last_priv *priv = nft_expr_priv(expr);

Annotation

Implementation Notes