net/ife/ife.c

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

File Facts

System
Linux kernel
Corpus path
net/ife/ife.c
Extension
.c
Size
4515 bytes
Lines
178
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: exported/initcall integration point
Status
integration 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 ifeheadr {
	__be16 metalen;
	u8 tlv_data[];
};

void *ife_encode(struct sk_buff *skb, u16 metalen)
{
	/* OUTERHDR:TOTMETALEN:{TLVHDR:Metadatum:TLVHDR..}:ORIGDATA
	 * where ORIGDATA = original ethernet header ...
	 */
	int hdrm = metalen + IFE_METAHDRLEN;
	int total_push = hdrm + skb->dev->hard_header_len;
	struct ifeheadr *ifehdr;
	struct ethhdr *iethh;	/* inner ether header */
	int skboff = 0;
	int err;

	err = skb_cow_head(skb, total_push);
	if (unlikely(err))
		return NULL;

	iethh = (struct ethhdr *) skb->data;

	__skb_push(skb, total_push);
	memcpy(skb->data, iethh, skb->dev->hard_header_len);
	skb_reset_mac_header(skb);
	skboff += skb->dev->hard_header_len;

	/* total metadata length */
	ifehdr = (struct ifeheadr *) (skb->data + skboff);
	metalen += IFE_METAHDRLEN;
	ifehdr->metalen = htons(metalen);

	return ifehdr->tlv_data;
}
EXPORT_SYMBOL_GPL(ife_encode);

void *ife_decode(struct sk_buff *skb, u16 *metalen)
{
	struct ifeheadr *ifehdr;
	int total_pull;
	u16 ifehdrln;

	if (!pskb_may_pull(skb, skb->dev->hard_header_len + IFE_METAHDRLEN))
		return NULL;

	ifehdr = (struct ifeheadr *) (skb->data + skb->dev->hard_header_len);
	ifehdrln = ntohs(ifehdr->metalen);
	total_pull = skb->dev->hard_header_len + ifehdrln;

	if (unlikely(ifehdrln < 2))
		return NULL;

	if (unlikely(!pskb_may_pull(skb, total_pull + ETH_HLEN)))
		return NULL;

	ifehdr = (struct ifeheadr *)(skb->data + skb->dev->hard_header_len);
	skb_set_mac_header(skb, total_pull);
	__skb_pull(skb, total_pull);
	*metalen = ifehdrln - IFE_METAHDRLEN;

	return &ifehdr->tlv_data;
}
EXPORT_SYMBOL_GPL(ife_decode);

struct meta_tlvhdr {
	__be16 type;
	__be16 len;
};

static bool __ife_tlv_meta_valid(const unsigned char *skbdata,
				 const unsigned char *ifehdr_end)
{
	const struct meta_tlvhdr *tlv;
	u16 tlvlen;

	if (unlikely(skbdata + sizeof(*tlv) > ifehdr_end))
		return false;

	tlv = (const struct meta_tlvhdr *)skbdata;
	tlvlen = ntohs(tlv->len);

	/* tlv length field is inc header, check on minimum */
	if (tlvlen < NLA_HDRLEN)
		return false;

	/* overflow by NLA_ALIGN check */
	if (NLA_ALIGN(tlvlen) < tlvlen)
		return false;

Annotation

Implementation Notes