This is a note to let you know that I've just added the patch titled
net_sched: cls_route: disallow handle of 0
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net_sched-cls_route-disallow-handle-of-0.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 02799571714dc5dd6948824b9d080b44a295f695 Mon Sep 17 00:00:00 2001
From: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Date: Sun, 14 Aug 2022 11:27:58 +0000
Subject: net_sched: cls_route: disallow handle of 0
From: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
commit 02799571714dc5dd6948824b9d080b44a295f695 upstream.
Follows up on:
https://lore.kernel.org/all/20220809170518.164662-1-cascardo@xxxxxxxxxxxxx/
handle of 0 implies from/to of universe realm which is not very
sensible.
Lets see what this patch will do:
$sudo tc qdisc add dev $DEV root handle 1:0 prio
//lets manufacture a way to insert handle of 0
$sudo tc filter add dev $DEV parent 1:0 protocol ip prio 100 \
route to 0 from 0 classid 1:10 action ok
//gets rejected...
Error: handle of 0 is not valid.
We have an error talking to the kernel, -1
//lets create a legit entry..
sudo tc filter add dev $DEV parent 1:0 protocol ip prio 100 route from 10 \
classid 1:10 action ok
//what did the kernel insert?
$sudo tc filter ls dev $DEV parent 1:0
filter protocol ip pref 100 route chain 0
filter protocol ip pref 100 route chain 0 fh 0x000a8000 flowid 1:10 from 10
action order 1: gact action pass
random type none pass val 0
index 1 ref 1 bind 1
//Lets try to replace that legit entry with a handle of 0
$ sudo tc filter replace dev $DEV parent 1:0 protocol ip prio 100 \
handle 0x000a8000 route to 0 from 0 classid 1:10 action drop
Error: Replacing with handle of 0 is invalid.
We have an error talking to the kernel, -1
And last, lets run Cascardo's POC:
$ ./poc
0
0
-22
-22
-22
Signed-off-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Acked-by: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/cls_route.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -424,6 +424,11 @@ static int route4_set_parms(struct net *
return -EINVAL;
}
+ if (!nhandle) {
+ NL_SET_ERR_MSG(extack, "Replacing with handle of 0 is invalid");
+ return -EINVAL;
+ }
+
h1 = to_hash(nhandle);
b = rtnl_dereference(head->table[h1]);
if (!b) {
@@ -477,6 +482,11 @@ static int route4_change(struct net *net
int err;
bool new = true;
+ if (!handle) {
+ NL_SET_ERR_MSG(extack, "Creating with handle of 0 is invalid");
+ return -EINVAL;
+ }
+
if (opt == NULL)
return handle ? -EINVAL : 0;
Patches currently in stable-queue which might be from jhs@xxxxxxxxxxxx are
queue-5.10/net_sched-cls_route-disallow-handle-of-0.patch
queue-5.10/net_sched-cls_route-remove-from-list-when-handle-is-0.patch
