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Date: Fri, 9 Jan 2015 11:43:26 -0800
From: Andy Lutomirski <luto@...capital.net>
To: Willem de Bruijn <willemb@...gle.com>
Cc: Network Development <netdev@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>,
Richard Cochran <richardcochran@...il.com>,
Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net-next RFC 1/5] net-timestamp: no-payload option
On Fri, Jan 9, 2015 at 9:31 AM, Willem de Bruijn <willemb@...gle.com> wrote:
> From: Willem de Bruijn <willemb@...gle.com>
>
> Add timestamping option SOF_TIMESTAMPING_OPT_TSONLY. For transmit
> timestamps, this loops timestamps on top of empty packets.
>
> Doing so reduces the pressure on SO_RCVBUF. Payload inspection and
> cmsg reception (aside from timestamps) are no longer possible. This
> works together with a follow on patch that allows administrators to
> only allow tx timestamping if it does not loop payload or metadata.
If this loses IP_PKTINFO, that will be a bit unfortunate.
--Andy
>
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>
> ---
> include/uapi/linux/net_tstamp.h | 3 ++-
> net/core/skbuff.c | 19 ++++++++++++++-----
> net/ipv4/ip_sockglue.c | 9 +++++----
> net/ipv6/datagram.c | 4 ++--
> net/rxrpc/ar-error.c | 5 +++++
> 5 files changed, 28 insertions(+), 12 deletions(-)
>
> diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h
> index edbc888..6d1abea 100644
> --- a/include/uapi/linux/net_tstamp.h
> +++ b/include/uapi/linux/net_tstamp.h
> @@ -24,8 +24,9 @@ enum {
> SOF_TIMESTAMPING_TX_SCHED = (1<<8),
> SOF_TIMESTAMPING_TX_ACK = (1<<9),
> SOF_TIMESTAMPING_OPT_CMSG = (1<<10),
> + SOF_TIMESTAMPING_OPT_TSONLY = (1<<11),
>
> - SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_CMSG,
> + SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_TSONLY,
> SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) |
> SOF_TIMESTAMPING_LAST
> };
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 5a2a2e8..ece2bb8 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -3710,19 +3710,28 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
> struct sock *sk, int tstype)
> {
> struct sk_buff *skb;
> + bool tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
>
> if (!sk)
> return;
>
> - if (hwtstamps)
> - *skb_hwtstamps(orig_skb) = *hwtstamps;
> + if (tsonly)
> + skb = alloc_skb(0, GFP_ATOMIC);
> else
> - orig_skb->tstamp = ktime_get_real();
> -
> - skb = skb_clone(orig_skb, GFP_ATOMIC);
> + skb = skb_clone(orig_skb, GFP_ATOMIC);
> if (!skb)
> return;
>
> + if (tsonly) {
> + skb_shinfo(skb)->tx_flags = skb_shinfo(orig_skb)->tx_flags;
> + skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
> + }
> +
> + if (hwtstamps)
> + *skb_hwtstamps(skb) = *hwtstamps;
> + else
> + skb->tstamp = ktime_get_real();
> +
> __skb_complete_tx_timestamp(skb, sk, tstype);
> }
> EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index a317797..d81ef70 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -440,7 +440,7 @@ static bool ipv4_pktinfo_prepare_errqueue(const struct sock *sk,
>
> if ((ee_origin != SO_EE_ORIGIN_TIMESTAMPING) ||
> (!(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_CMSG)) ||
> - (!skb->dev))
> + (!skb->dev) || (!skb->len))
> return false;
>
> info->ipi_spec_dst.s_addr = ip_hdr(skb)->saddr;
> @@ -483,7 +483,7 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
>
> serr = SKB_EXT_ERR(skb);
>
> - if (sin) {
> + if (sin && skb->len) {
> sin->sin_family = AF_INET;
> sin->sin_addr.s_addr = *(__be32 *)(skb_network_header(skb) +
> serr->addr_offset);
> @@ -496,8 +496,9 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
> sin = &errhdr.offender;
> sin->sin_family = AF_UNSPEC;
>
> - if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
> - ipv4_pktinfo_prepare_errqueue(sk, skb, serr->ee.ee_origin)) {
> + if (skb->len &&
> + (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
> + ipv4_pktinfo_prepare_errqueue(sk, skb, serr->ee.ee_origin))) {
> struct inet_sock *inet = inet_sk(sk);
>
> sin->sin_family = AF_INET;
> diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
> index 100c589..91a31ea 100644
> --- a/net/ipv6/datagram.c
> +++ b/net/ipv6/datagram.c
> @@ -369,7 +369,7 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
>
> serr = SKB_EXT_ERR(skb);
>
> - if (sin) {
> + if (sin && skb->len) {
> const unsigned char *nh = skb_network_header(skb);
> sin->sin6_family = AF_INET6;
> sin->sin6_flowinfo = 0;
> @@ -394,7 +394,7 @@ int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
> memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
> sin = &errhdr.offender;
> sin->sin6_family = AF_UNSPEC;
> - if (serr->ee.ee_origin != SO_EE_ORIGIN_LOCAL) {
> + if (serr->ee.ee_origin != SO_EE_ORIGIN_LOCAL && skb->len) {
> sin->sin6_family = AF_INET6;
> sin->sin6_flowinfo = 0;
> sin->sin6_port = 0;
> diff --git a/net/rxrpc/ar-error.c b/net/rxrpc/ar-error.c
> index 74c0fcd..5394b6b 100644
> --- a/net/rxrpc/ar-error.c
> +++ b/net/rxrpc/ar-error.c
> @@ -42,6 +42,11 @@ void rxrpc_UDP_error_report(struct sock *sk)
> _leave("UDP socket errqueue empty");
> return;
> }
> + if (!skb->len) {
> + _leave("UDP empty message");
> + kfree_skb(skb);
> + return;
> + }
>
> rxrpc_new_skb(skb);
>
> --
> 2.2.0.rc0.207.ga3a616c
>
--
Andy Lutomirski
AMA Capital Management, LLC
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