diff options
| author | Vadim Fedorenko <vadfed@meta.com> | 2024-02-13 03:04:28 -0800 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2024-02-15 12:04:04 +0100 |
| commit | 488b6d91b07112eaaaa4454332c1480894d4e06e (patch) | |
| tree | 3dc7052af956c4df9e8de2353d41061a11c8d619 /net/ipv6 | |
| parent | 2ec197fda25f57afccac7f2846e509471488614c (diff) | |
net-timestamp: make sk_tskey more predictable in error path
When SOF_TIMESTAMPING_OPT_ID is used to ambiguate timestamped datagrams,
the sk_tskey can become unpredictable in case of any error happened
during sendmsg(). Move increment later in the code and make decrement of
sk_tskey in error path. This solution is still racy in case of multiple
threads doing snedmsg() over the very same socket in parallel, but still
makes error path much more predictable.
Fixes: 09c2d251b707 ("net-timestamp: add key to disambiguate concurrent datagrams")
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20240213110428.1681540-1-vadfed@meta.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/ip6_output.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index a722a43dd668..31b86fe661aa 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1424,11 +1424,11 @@ static int __ip6_append_data(struct sock *sk, bool zc = false; u32 tskey = 0; struct rt6_info *rt = (struct rt6_info *)cork->dst; + bool paged, hold_tskey, extra_uref = false; struct ipv6_txoptions *opt = v6_cork->opt; int csummode = CHECKSUM_NONE; unsigned int maxnonfragsize, headersize; unsigned int wmem_alloc_delta = 0; - bool paged, extra_uref = false; skb = skb_peek_tail(queue); if (!skb) { @@ -1440,10 +1440,6 @@ static int __ip6_append_data(struct sock *sk, mtu = cork->gso_size ? IP6_MAX_MTU : cork->fragsize; orig_mtu = mtu; - if (cork->tx_flags & SKBTX_ANY_TSTAMP && - READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) - tskey = atomic_inc_return(&sk->sk_tskey) - 1; - hh_len = LL_RESERVED_SPACE(rt->dst.dev); fragheaderlen = sizeof(struct ipv6hdr) + rt->rt6i_nfheader_len + @@ -1538,6 +1534,11 @@ emsgsize: flags &= ~MSG_SPLICE_PAGES; } + hold_tskey = cork->tx_flags & SKBTX_ANY_TSTAMP && + READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID; + if (hold_tskey) + tskey = atomic_inc_return(&sk->sk_tskey) - 1; + /* * Let's try using as much space as possible. * Use MTU if total length of the message fits into the MTU. @@ -1794,6 +1795,8 @@ error: cork->length -= length; IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS); refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); + if (hold_tskey) + atomic_dec(&sk->sk_tskey); return err; } |