From 8913336a7e8d56e984109a3137d6c0e3362596a4 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Fri, 18 Jul 2008 18:05:19 -0700 Subject: [PATCH] packet: add PACKET_RESERVE sockopt Add new sockopt to reserve some headroom in the mmaped ring frames in front of the packet payload. This can be used f.i. when the VLAN header needs to be (re)constructed to avoid moving the entire payload. Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- include/linux/if_packet.h | 1 + net/packet/af_packet.c | 29 ++++++++++++++++++++++++++--- 2 files changed, 27 insertions(+), 3 deletions(-) diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h index a630295b255f..18db0668065a 100644 --- a/include/linux/if_packet.h +++ b/include/linux/if_packet.h @@ -45,6 +45,7 @@ struct sockaddr_ll #define PACKET_ORIGDEV 9 #define PACKET_VERSION 10 #define PACKET_HDRLEN 11 +#define PACKET_RESERVE 12 struct tpacket_stats { diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index db792e02a37f..de73bcb5235a 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -188,6 +188,7 @@ struct packet_sock { unsigned int pg_vec_len; enum tpacket_versions tp_version; unsigned int tp_hdrlen; + unsigned int tp_reserve; #endif }; @@ -635,11 +636,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe snaplen = res; if (sk->sk_type == SOCK_DGRAM) { - macoff = netoff = TPACKET_ALIGN(po->tp_hdrlen) + 16; + macoff = netoff = TPACKET_ALIGN(po->tp_hdrlen) + 16 + + po->tp_reserve; } else { unsigned maclen = skb_network_offset(skb); netoff = TPACKET_ALIGN(po->tp_hdrlen + - (maclen < 16 ? 16 : maclen)); + (maclen < 16 ? 16 : maclen)) + + po->tp_reserve; macoff = netoff - maclen; } @@ -1448,6 +1451,19 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv return -EINVAL; } } + case PACKET_RESERVE: + { + unsigned int val; + + if (optlen != sizeof(val)) + return -EINVAL; + if (po->pg_vec) + return -EBUSY; + if (copy_from_user(&val, optval, sizeof(val))) + return -EFAULT; + po->tp_reserve = val; + return 0; + } #endif case PACKET_AUXDATA: { @@ -1547,6 +1563,12 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, } data = &val; break; + case PACKET_RESERVE: + if (len > sizeof(unsigned int)) + len = sizeof(unsigned int); + val = po->tp_reserve; + data = &val; + break; #endif default: return -ENOPROTOOPT; @@ -1790,7 +1812,8 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing return -EINVAL; if (unlikely(req->tp_block_size & (PAGE_SIZE - 1))) return -EINVAL; - if (unlikely(req->tp_frame_size < po->tp_hdrlen)) + if (unlikely(req->tp_frame_size < po->tp_hdrlen + + po->tp_reserve)) return -EINVAL; if (unlikely(req->tp_frame_size & (TPACKET_ALIGNMENT - 1))) return -EINVAL; -- 2.20.1