summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--Documentation/networking/packet_mmap.txt13
-rw-r--r--include/uapi/linux/if_packet.h1
-rw-r--r--net/packet/af_packet.c46
-rw-r--r--net/packet/internal.h1
4 files changed, 60 insertions, 1 deletions
diff --git a/Documentation/networking/packet_mmap.txt b/Documentation/networking/packet_mmap.txt
index 1c08a4b..7cd879e 100644
--- a/Documentation/networking/packet_mmap.txt
+++ b/Documentation/networking/packet_mmap.txt
@@ -163,6 +163,19 @@ As capture, each frame contains two parts:
A complete tutorial is available at: http://wiki.gnu-log.net/
+By default, the user should put data at :
+ frame base + TPACKET_HDRLEN - sizeof(struct sockaddr_ll)
+
+So, whatever you choose for the socket mode (SOCK_DGRAM or SOCK_RAW),
+the beginning of the user data will be at :
+ frame base + TPACKET_ALIGN(sizeof(struct tpacket_hdr))
+
+If you wish to put user data at a custom offset from the beginning of
+the frame (for payload alignment with SOCK_RAW mode for instance) you
+can set tp_net (with SOCK_DGRAM) or tp_mac (with SOCK_RAW). In order
+to make this work it must be enabled previously with setsockopt()
+and the PACKET_TX_HAS_OFF option.
+
--------------------------------------------------------------------------------
+ PACKET_MMAP settings
--------------------------------------------------------------------------------
diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
index f379929..f9a6037 100644
--- a/include/uapi/linux/if_packet.h
+++ b/include/uapi/linux/if_packet.h
@@ -50,6 +50,7 @@ struct sockaddr_ll {
#define PACKET_TX_TIMESTAMP 16
#define PACKET_TIMESTAMP 17
#define PACKET_FANOUT 18
+#define PACKET_TX_HAS_OFF 19
#define PACKET_FANOUT_HASH 0
#define PACKET_FANOUT_LB 1
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 9034f52..f262dbf 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1881,7 +1881,35 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
skb_reserve(skb, hlen);
skb_reset_network_header(skb);
- data = ph.raw + po->tp_hdrlen - sizeof(struct sockaddr_ll);
+ if (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) {
@@ -3109,6 +3137,19 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
return fanout_add(sk, val & 0xffff, val >> 16);
}
+ case PACKET_TX_HAS_OFF:
+ {
+ unsigned int val;
+
+ if (optlen != sizeof(val))
+ return -EINVAL;
+ if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
+ return -EBUSY;
+ if (copy_from_user(&val, optval, sizeof(val)))
+ return -EFAULT;
+ po->tp_tx_has_off = !!val;
+ return 0;
+ }
default:
return -ENOPROTOOPT;
}
@@ -3200,6 +3241,9 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
((u32)po->fanout->type << 16)) :
0);
break;
+ case PACKET_TX_HAS_OFF:
+ val = po->tp_tx_has_off;
+ break;
default:
return -ENOPROTOOPT;
}
diff --git a/net/packet/internal.h b/net/packet/internal.h
index 44945f6..e84cab8 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -109,6 +109,7 @@ struct packet_sock {
unsigned int tp_hdrlen;
unsigned int tp_reserve;
unsigned int tp_loss:1;
+ unsigned int tp_tx_has_off:1;
unsigned int tp_tstamp;
struct packet_type prot_hook ____cacheline_aligned_in_smp;
};
OpenPOWER on IntegriCloud