diff options
| author | Eyal Birger <eyal.birger@gmail.com> | 2015-03-01 14:58:28 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-03-02 00:19:29 -0500 |
| commit | 2472d7613bd3bae40a7dc75539c0858d5b9e795a (patch) | |
| tree | 0c08b919ed13050fef72a0e2f1f8552157d833ea /net/packet | |
| parent | 2cfdf9fcb85bf6c0bb4556384ba800b9f443f601 (diff) | |
| download | linux-2472d7613bd3bae40a7dc75539c0858d5b9e795a.tar.bz2 | |
net: packet: use sockaddr_ll fields as storage for skb original length in recvmsg path
As part of an effort to move skb->dropcount to skb->cb[], 4 bytes
of additional room are needed in skb->cb[] in packet sockets.
Store the skb original length in the first two fields of sockaddr_ll
(sll_family and sll_protocol) as they can be derived from the skb when
needed.
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
| -rw-r--r-- | net/packet/af_packet.c | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 9c28cec1a083..7eea30b9c8e5 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -216,10 +216,16 @@ static void prb_fill_vlan_info(struct tpacket_kbdq_core *, static void packet_flush_mclist(struct sock *sk); struct packet_skb_cb { - unsigned int origlen; union { struct sockaddr_pkt pkt; - struct sockaddr_ll ll; + union { + /* Trick: alias skb original length with + * ll.sll_family and ll.protocol in order + * to save room. + */ + unsigned int origlen; + struct sockaddr_ll ll; + }; } sa; }; @@ -1814,9 +1820,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, sizeof(skb->cb)); sll = &PACKET_SKB_CB(skb)->sa.ll; - sll->sll_family = AF_PACKET; sll->sll_hatype = dev->type; - sll->sll_protocol = skb->protocol; sll->sll_pkttype = skb->pkt_type; if (unlikely(po->origdev)) sll->sll_ifindex = orig_dev->ifindex; @@ -1825,7 +1829,10 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, sll->sll_halen = dev_parse_header(skb, sll->sll_addr); - PACKET_SKB_CB(skb)->origlen = skb->len; + /* sll->sll_family and sll->sll_protocol are set in packet_recvmsg(). + * Use their space for storing the original skb length. + */ + PACKET_SKB_CB(skb)->sa.origlen = skb->len; if (pskb_trim(skb, snaplen)) goto drop_n_acct; @@ -2883,6 +2890,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock, struct sk_buff *skb; int copied, err; int vnet_hdr_len = 0; + unsigned int origlen = 0; err = -EINVAL; if (flags & ~(MSG_PEEK|MSG_DONTWAIT|MSG_TRUNC|MSG_CMSG_COMPAT|MSG_ERRQUEUE)) @@ -2982,6 +2990,15 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock, if (err) goto out_free; + if (sock->type != SOCK_PACKET) { + struct sockaddr_ll *sll = &PACKET_SKB_CB(skb)->sa.ll; + + /* Original length was stored in sockaddr_ll fields */ + origlen = PACKET_SKB_CB(skb)->sa.origlen; + sll->sll_family = AF_PACKET; + sll->sll_protocol = skb->protocol; + } + sock_recv_ts_and_drops(msg, sk, skb); if (msg->msg_name) { @@ -2993,6 +3010,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock, msg->msg_namelen = sizeof(struct sockaddr_pkt); } else { struct sockaddr_ll *sll = &PACKET_SKB_CB(skb)->sa.ll; + msg->msg_namelen = sll->sll_halen + offsetof(struct sockaddr_ll, sll_addr); } @@ -3006,7 +3024,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock, aux.tp_status = TP_STATUS_USER; if (skb->ip_summed == CHECKSUM_PARTIAL) aux.tp_status |= TP_STATUS_CSUMNOTREADY; - aux.tp_len = PACKET_SKB_CB(skb)->origlen; + aux.tp_len = origlen; aux.tp_snaplen = skb->len; aux.tp_mac = 0; aux.tp_net = skb_network_offset(skb); |