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Commit 8d39b4a6 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller
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packet: parse tpacket header before skb alloc 



GSO packet headers must be stored in the linear skb segment.
Move tpacket header parsing before sock_alloc_send_skb. The GSO
follow-on patch will later increase the skb linear argument to
sock_alloc_send_skb if needed for large packets.

The header parsing code does not require an allocated skb, so is
safe to move. Later pass to tpacket_fill_skb the computed data
start and length.

Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 58d19b19

net/packet/af_packet.c

+65 −46
Original line number Diff line number Diff line
@@ -2494,14 +2494,13 @@ static int packet_snd_vnet_gso(struct sk_buff *skb, 
}



static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,

		void *frame, struct net_device *dev, int size_max,

		void *frame, struct net_device *dev, void *data, int tp_len,

		__be16 proto, unsigned char *addr, int hlen)

{

	union tpacket_uhdr ph;

	int to_write, offset, len, tp_len, nr_frags, len_max;

	int to_write, offset, len, nr_frags, len_max;

	struct socket *sock = po->sk.sk_socket;

	struct page *page;

	void *data;

	int err;



	ph.raw = frame;
@@ -2513,51 +2512,9 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb, 
	sock_tx_timestamp(&po->sk, &skb_shinfo(skb)->tx_flags);

	skb_shinfo(skb)->destructor_arg = ph.raw;



	switch (po->tp_version) {

	case TPACKET_V2:

		tp_len = ph.h2->tp_len;

		break;

	default:

		tp_len = ph.h1->tp_len;

		break;

	}

	if (unlikely(tp_len > size_max)) {

		pr_err("packet size is too long (%d > %d)\n", tp_len, size_max);

		return -EMSGSIZE;

	}



	skb_reserve(skb, hlen);

	skb_reset_network_header(skb);



	if (unlikely(po->tp_tx_has_off)) {

		int off_min, off_max, off;

		off_min = po->tp_hdrlen - sizeof(struct sockaddr_ll);

		off_max = po->tx_ring.frame_size - tp_len;

		if (sock->type == SOCK_DGRAM) {

			switch (po->tp_version) {

			case TPACKET_V2:

				off = ph.h2->tp_net;

				break;

			default:

				off = ph.h1->tp_net;

				break;

			}

		} else {

			switch (po->tp_version) {

			case TPACKET_V2:

				off = ph.h2->tp_mac;

				break;

			default:

				off = ph.h1->tp_mac;

				break;

			}

		}

		if (unlikely((off < off_min) || (off_max < off)))

			return -EINVAL;

		data = ph.raw + off;

	} else {

		data = ph.raw + po->tp_hdrlen - sizeof(struct sockaddr_ll);

	}

	to_write = tp_len;



	if (sock->type == SOCK_DGRAM) {
@@ -2615,6 +2572,61 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb, 
	return tp_len;

}



static int tpacket_parse_header(struct packet_sock *po, void *frame,

				int size_max, void **data)

{

	union tpacket_uhdr ph;

	int tp_len, off;



	ph.raw = frame;



	switch (po->tp_version) {

	case TPACKET_V2:

		tp_len = ph.h2->tp_len;

		break;

	default:

		tp_len = ph.h1->tp_len;

		break;

	}

	if (unlikely(tp_len > size_max)) {

		pr_err("packet size is too long (%d > %d)\n", tp_len, size_max);

		return -EMSGSIZE;

	}



	if (unlikely(po->tp_tx_has_off)) {

		int off_min, off_max;



		off_min = po->tp_hdrlen - sizeof(struct sockaddr_ll);

		off_max = po->tx_ring.frame_size - tp_len;

		if (po->sk.sk_type == SOCK_DGRAM) {

			switch (po->tp_version) {

			case TPACKET_V2:

				off = ph.h2->tp_net;

				break;

			default:

				off = ph.h1->tp_net;

				break;

			}

		} else {

			switch (po->tp_version) {

			case TPACKET_V2:

				off = ph.h2->tp_mac;

				break;

			default:

				off = ph.h1->tp_mac;

				break;

			}

		}

		if (unlikely((off < off_min) || (off_max < off)))

			return -EINVAL;

	} else {

		off = po->tp_hdrlen - sizeof(struct sockaddr_ll);

	}



	*data = frame + off;

	return tp_len;

}



static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)

{

	struct sk_buff *skb;
@@ -2626,6 +2638,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) 
	bool need_wait = !(msg->msg_flags & MSG_DONTWAIT);

	int tp_len, size_max;

	unsigned char *addr;

	void *data;

	int len_sum = 0;

	int status = TP_STATUS_AVAILABLE;

	int hlen, tlen;
@@ -2673,6 +2686,11 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) 
			continue;

		}



		skb = NULL;

		tp_len = tpacket_parse_header(po, ph, size_max, &data);

		if (tp_len < 0)

			goto tpacket_error;



		status = TP_STATUS_SEND_REQUEST;

		hlen = LL_RESERVED_SPACE(dev);

		tlen = dev->needed_tailroom;
@@ -2686,7 +2704,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) 
				err = len_sum;

			goto out_status;

		}

		tp_len = tpacket_fill_skb(po, skb, ph, dev, size_max, proto,

		tp_len = tpacket_fill_skb(po, skb, ph, dev, data, tp_len, proto,

					  addr, hlen);

		if (likely(tp_len >= 0) &&

		    tp_len > dev->mtu + reserve &&
@@ -2694,6 +2712,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) 
			tp_len = -EMSGSIZE;



		if (unlikely(tp_len < 0)) {

tpacket_error:

			if (po->tp_loss) {

				__packet_set_status(po, ph,

						TP_STATUS_AVAILABLE);