From 49ca0d8bfaf3bc46d5eef60ce67b00eb195bd392 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Fri, 30 Jan 2015 13:29:31 -0500 Subject: [PATCH] net-timestamp: no-payload option 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. Signed-off-by: Willem de Bruijn ---- Changes (rfc -> v1) - add documentation - remove unnecessary skb->len test (thanks to Richard Cochran) Signed-off-by: David S. Miller --- Documentation/networking/timestamping.txt | 21 +++++++++++++++++++++ include/uapi/linux/net_tstamp.h | 3 ++- net/core/skbuff.c | 19 ++++++++++++++----- net/ipv4/ip_sockglue.c | 7 ++++--- net/ipv6/datagram.c | 5 ++--- net/rxrpc/ar-error.c | 5 +++++ 6 files changed, 48 insertions(+), 12 deletions(-) diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt index a5c784c89312..5f0922613f1a 100644 --- a/Documentation/networking/timestamping.txt +++ b/Documentation/networking/timestamping.txt @@ -162,6 +162,27 @@ SOF_TIMESTAMPING_OPT_CMSG: option IP_PKTINFO simultaneously. +SOF_TIMESTAMPING_OPT_TSONLY: + + Applies to transmit timestamps only. Makes the kernel return the + timestamp as a cmsg alongside an empty packet, as opposed to + alongside the original packet. This reduces the amount of memory + charged to the socket's receive budget (SO_RCVBUF) and delivers + the timestamp even if sysctl net.core.tstamp_allow_data is 0. + This option disables SOF_TIMESTAMPING_OPT_CMSG. + + +New applications are encouraged to pass SOF_TIMESTAMPING_OPT_ID to +disambiguate timestamps and SOF_TIMESTAMPING_OPT_TSONLY to operate +regardless of the setting of sysctl net.core.tstamp_allow_data. + +An exception is when a process needs additional cmsg data, for +instance SOL_IP/IP_PKTINFO to detect the egress network interface. +Then pass option SOF_TIMESTAMPING_OPT_CMSG. This option depends on +having access to the contents of the original packet, so cannot be +combined with SOF_TIMESTAMPING_OPT_TSONLY. + + 1.4 Bytestream Timestamps The SO_TIMESTAMPING interface supports timestamping of bytes in a diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h index edbc888ceb51..6d1abea9746e 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 56db472e9b86..65a3798f43e6 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 db5e0f81ce0a..31d8c71986b4 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -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; memset(sin, 0, sizeof(*sin)); - 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))) { sin->sin_family = AF_INET; sin->sin_addr.s_addr = ip_hdr(skb)->saddr; if (inet_sk(sk)->cmsg_flags) diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c index 49f5e73db122..c215be70cac0 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; @@ -394,8 +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; memset(sin, 0, sizeof(*sin)); - - 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; if (np->rxopt.all) { if (serr->ee.ee_origin != SO_EE_ORIGIN_ICMP && diff --git a/net/rxrpc/ar-error.c b/net/rxrpc/ar-error.c index 74c0fcd36838..5394b6be46ec 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); -- 2.20.1