[PATCH v2 0/1] net/sched: taprio: Check if sk_flags are valid

[PATCH v2 0/1] net/sched: taprio: Check if sk_flags are valid

[Benedikt Spranger]

While testing the software based scheduling of the taprio scheduler
new TCP connection failed to establish. Digging it down let to a missing
validity check in the enqueue function. Add the missing check.

v1..v2:
Fix a typo
Add a acked-by

Benedikt Spranger (1):
  net/sched: taprio: Check if socket flags are valid

 net/sched/sch_taprio.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

-- 
2.20.1

[PATCH v2 1/1] net/sched: taprio: Check if socket flags are valid

[Benedikt Spranger]

A user may set the SO_TXTIME socket option to ensure a packet is send
at a given time. The taprio scheduler has to confirm, that it is allowed
to send a packet at that given time, by a check against the packet time
schedule. The scheduler drop the packet, if the gates are closed at the
given send time.

The check, if SO_TXTIME is set, may fail since sk_flags are part of an
union and the union is used otherwise. This happen, if a socket is not
a full socket, like a request socket for example.

Add a check to verify, if the union is used for sk_flags.

Fixes: 4cfd5779bd6e ("taprio: Add support for txtime-assist mode")
Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
---
 net/sched/sch_taprio.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 1ce6416b4810..a871b3ef4bca 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -419,7 +419,8 @@ static int taprio_enqueue_one(struct sk_buff *skb, struct Qdisc *sch,
 {
 	struct taprio_sched *q = qdisc_priv(sch);
 
-	if (skb->sk && sock_flag(skb->sk, SOCK_TXTIME)) {
+	/* sk_flags are only safe to use on full sockets. */
+	if (skb->sk && sk_fullsock(skb->sk) && sock_flag(skb->sk, SOCK_TXTIME)) {
 		if (!is_valid_interval(skb, sch))
 			return qdisc_drop(skb, sch, to_free);
 	} else if (TXTIME_ASSIST_IS_ENABLED(q->flags)) {
-- 
2.20.1

Re: [PATCH v2 0/1] net/sched: taprio: Check if sk_flags are valid

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Fri,  8 Apr 2022 11:47:44 +0200 you wrote:
> While testing the software based scheduling of the taprio scheduler
> new TCP connection failed to establish. Digging it down let to a missing
> validity check in the enqueue function. Add the missing check.
> 
> v1..v2:
> Fix a typo
> Add a acked-by
> 
> [...]

Here is the summary with links:
  - [v2,1/1] net/sched: taprio: Check if socket flags are valid
    https://git.kernel.org/netdev/net/c/e8a64bbaaad1

You are awesome, thank you!
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