[PATCH 4.10 37/62] tcp: mark skbs with SCM_TIMESTAMPING_OPT_STATS

[Greg Kroah-Hartman]

4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Soheil Hassas Yeganeh <soh...@google.com>


[ Upstream commit 4ef1b2869447411ad3ef91ad7d4891a83c1a509a ]

SOF_TIMESTAMPING_OPT_STATS can be enabled and disabled
while packets are collected on the error queue.
So, checking SOF_TIMESTAMPING_OPT_STATS in sk->sk_tsflags
is not enough to safely assume that the skb contains
OPT_STATS data.

Add a bit in sock_exterr_skb to indicate whether the
skb contains opt_stats data.

Fixes: 1c885808e456 ("tcp: SOF_TIMESTAMPING_OPT_STATS option for 
SO_TIMESTAMPING")
Reported-by: JongHwan Kim <zzoru...@gmail.com>
Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: Willem de Bruijn <will...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 include/linux/errqueue.h |    2 ++
 net/core/skbuff.c        |   17 +++++++++++------
 net/socket.c             |    2 +-
 3 files changed, 14 insertions(+), 7 deletions(-)

--- a/include/linux/errqueue.h
+++ b/include/linux/errqueue.h
@@ -20,6 +20,8 @@ struct sock_exterr_skb {
        struct sock_extended_err        ee;
        u16                             addr_offset;
        __be16                          port;
+       u8                              opt_stats:1,
+                                       unused:7;
 };
 
 #endif
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3799,16 +3799,20 @@ EXPORT_SYMBOL(skb_clone_sk);
 
 static void __skb_complete_tx_timestamp(struct sk_buff *skb,
                                        struct sock *sk,
-                                       int tstype)
+                                       int tstype,
+                                       bool opt_stats)
 {
        struct sock_exterr_skb *serr;
        int err;
 
+       BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));
+
        serr = SKB_EXT_ERR(skb);
        memset(serr, 0, sizeof(*serr));
        serr->ee.ee_errno = ENOMSG;
        serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
        serr->ee.ee_info = tstype;
+       serr->opt_stats = opt_stats;
        serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0;
        if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID) {
                serr->ee.ee_data = skb_shinfo(skb)->tskey;
@@ -3850,7 +3854,7 @@ void skb_complete_tx_timestamp(struct sk
         */
        if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {
                *skb_hwtstamps(skb) = *hwtstamps;
-               __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
+               __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
                sock_put(sk);
        }
 }
@@ -3861,7 +3865,7 @@ void __skb_tstamp_tx(struct sk_buff *ori
                     struct sock *sk, int tstype)
 {
        struct sk_buff *skb;
-       bool tsonly;
+       bool tsonly, opt_stats = false;
 
        if (!sk)
                return;
@@ -3874,9 +3878,10 @@ void __skb_tstamp_tx(struct sk_buff *ori
 #ifdef CONFIG_INET
                if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
                    sk->sk_protocol == IPPROTO_TCP &&
-                   sk->sk_type == SOCK_STREAM)
+                   sk->sk_type == SOCK_STREAM) {
                        skb = tcp_get_timestamping_opt_stats(sk);
-               else
+                       opt_stats = true;
+               } else
 #endif
                        skb = alloc_skb(0, GFP_ATOMIC);
        } else {
@@ -3895,7 +3900,7 @@ void __skb_tstamp_tx(struct sk_buff *ori
        else
                skb->tstamp = ktime_get_real();
 
-       __skb_complete_tx_timestamp(skb, sk, tstype);
+       __skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
 }
 EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
 
--- a/net/socket.c
+++ b/net/socket.c
@@ -708,7 +708,7 @@ void __sock_recv_timestamp(struct msghdr
                         SCM_TIMESTAMPING, sizeof(tss), &tss);
 
                if (skb_is_err_queue(skb) && skb->len &&
-                   (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS))
+                   SKB_EXT_ERR(skb)->opt_stats)
                        put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPING_OPT_STATS,
                                 skb->len, skb->data);
        }