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authorJamal Hadi Salim <jhs@mojatatu.com>2022-08-14 14:27:58 +0300
committerDavid S. Miller <davem@davemloft.net>2022-08-15 13:46:30 +0300
commit02799571714dc5dd6948824b9d080b44a295f695 (patch)
treed56cdc0ebef2d41b5b6a8e15c482f158c5de1bfc /net
parent7396ba87f1edf549284869451665c7c4e74ecd4f (diff)
downloadlinux-02799571714dc5dd6948824b9d080b44a295f695.tar.xz
net_sched: cls_route: disallow handle of 0
Follows up on: https://lore.kernel.org/all/20220809170518.164662-1-cascardo@canonical.com/ 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@mojatatu.com> Acked-by: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/sched/cls_route.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index 3f935cbbaff6..48712bc51bda 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -424,6 +424,11 @@ static int route4_set_parms(struct net *net, struct tcf_proto *tp,
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, struct sk_buff *in_skb,
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;