[RFC PATCH net-next 2/2] net: Reset forwarded skb->tstamp before delivering to user space
flat view
STALE1777d
From: Martin KaFai Lau <hidden>
Date: 2021-12-07 02:01:16
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The skb->tstamp may be set by a local sk (as a sender in tcp) which then
forwarded and delivered to another sk (as a receiver).
An example:
sender-sk => veth@netns =====> veth@host => receiver-sk
^^^
__dev_forward_skb
The skb->tstamp is marked with a future TX time. This future
skb->tstamp will confuse the receiver-sk.
This patch marks the skb if the skb->tstamp is forwarded.
Before using the skb->tstamp as a rx timestamp, it needs
to be re-stamped to avoid getting a future time. It is
done in the RX timestamp reading helper skb_get_ktime().
Signed-off-by: Martin KaFai Lau <redacted>
---
include/linux/skbuff.h | 14 +++++++++-----
net/core/dev.c | 4 +++-
net/core/skbuff.c | 6 +++++-
3 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index b609bdc5398b..bc4ae34c4e22 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h@@ -867,6 +867,7 @@ struct sk_buff { __u8 decrypted:1; #endif __u8 slow_gro:1; + __u8 fwd_tstamp:1; #ifdef CONFIG_NET_SCHED __u16 tc_index; /* traffic control index */
@@ -3806,9 +3807,12 @@ static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb, } void skb_init(void); +void net_timestamp_set(struct sk_buff *skb); -static inline ktime_t skb_get_ktime(const struct sk_buff *skb) +static inline ktime_t skb_get_ktime(struct sk_buff *skb) { + if (unlikely(skb->fwd_tstamp)) + net_timestamp_set(skb); return ktime_mono_to_real_cond(skb->tstamp); }
@@ -3821,13 +3825,13 @@ static inline ktime_t skb_get_ktime(const struct sk_buff *skb) * This function converts the offset back to a struct timeval and stores * it in stamp. */ -static inline void skb_get_timestamp(const struct sk_buff *skb, +static inline void skb_get_timestamp(struct sk_buff *skb, struct __kernel_old_timeval *stamp) { *stamp = ns_to_kernel_old_timeval(skb_get_ktime(skb)); } -static inline void skb_get_new_timestamp(const struct sk_buff *skb, +static inline void skb_get_new_timestamp(struct sk_buff *skb, struct __kernel_sock_timeval *stamp) { struct timespec64 ts = ktime_to_timespec64(skb_get_ktime(skb));
@@ -3836,7 +3840,7 @@ static inline void skb_get_new_timestamp(const struct sk_buff *skb, stamp->tv_usec = ts.tv_nsec / 1000; } -static inline void skb_get_timestampns(const struct sk_buff *skb, +static inline void skb_get_timestampns(struct sk_buff *skb, struct __kernel_old_timespec *stamp) { struct timespec64 ts = ktime_to_timespec64(skb_get_ktime(skb));
@@ -3845,7 +3849,7 @@ static inline void skb_get_timestampns(const struct sk_buff *skb, stamp->tv_nsec = ts.tv_nsec; } -static inline void skb_get_new_timestampns(const struct sk_buff *skb, +static inline void skb_get_new_timestampns(struct sk_buff *skb, struct __kernel_timespec *stamp) { struct timespec64 ts = ktime_to_timespec64(skb_get_ktime(skb));
diff --git a/net/core/dev.c b/net/core/dev.c
index 4420086f3aeb..96cd31d9a359 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -2058,12 +2058,14 @@ void net_disable_timestamp(void) } EXPORT_SYMBOL(net_disable_timestamp); -static inline void net_timestamp_set(struct sk_buff *skb) +void net_timestamp_set(struct sk_buff *skb) { skb->tstamp = 0; + skb->fwd_tstamp = 0; if (static_branch_unlikely(&netstamp_needed_key)) __net_timestamp(skb); } +EXPORT_SYMBOL(net_timestamp_set); #define net_timestamp_check(COND, SKB) \ if (static_branch_unlikely(&netstamp_needed_key)) { \
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f091c7807a9e..181ddc989ead 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -5295,8 +5295,12 @@ void skb_scrub_tstamp(struct sk_buff *skb) { struct sock *sk = skb->sk; - if (sk && sk_fullsock(sk) && sock_flag(sk, SOCK_TXTIME)) + if (sk && sk_fullsock(sk) && sock_flag(sk, SOCK_TXTIME)) { skb->tstamp = 0; + skb->fwd_tstamp = 0; + } else if (skb->tstamp) { + skb->fwd_tstamp = 1; + } } /**
--
2.30.2