From: Al Viro <v...@zeniv.linux.org.uk>
... and produce consistent error on attempt to delete such.
Existing check in u32_delete() is inconsistent - after
tc qdisc add dev eth0 ingress
tc filter add dev eth0 parent ffff: protocol ip prio 100 handle 1: u32 divisor 1
tc filter add dev eth0 parent ffff: protocol ip prio 200 handle 2: u32 divisor 1
both
tc filter delete dev eth0 parent ffff: protocol ip prio 100 handle 801: u32
and
tc filter delete dev eth0 parent ffff: protocol ip prio 100 handle 800: u32
will fail (at least with refcounting fixes), but the former will complain
about an attempt to remove a busy table, while the latter will recognize
it as root and yield "Not allowed to delete root node" instead.
The problem with the existing check is that several tcf_proto instances might
share the same tp->data and handle-to-hnode lookup will be the same for all
of them. So comparing an hnode to be deleted with tp->root won't catch the
case when one tp is used to try deleting the root of another. Solution is
trivial - mark the root hnodes explicitly upon allocation and check for that.
Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
---
net/sched/cls_u32.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index b2c3406a2cf2..c4782aa808c7 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -84,6 +84,7 @@ struct tc_u_hnode {
int refcnt;
unsigned int divisor;
struct idr handle_idr;
+ bool is_root;
struct rcu_head rcu;
u32 flags;
/* The 'ht' field MUST be the last field in structure to allow for
@@ -377,6 +378,7 @@ static int u32_init(struct tcf_proto *tp)
root_ht->refcnt++;
root_ht->handle = tp_c ? gen_new_htid(tp_c, root_ht) : 0x80000000;
root_ht->prio = tp->prio;
+ root_ht->is_root = true;
idr_init(&root_ht->handle_idr);
if (tp_c == NULL) {
@@ -693,7 +695,7 @@ static int u32_delete(struct tcf_proto *tp, void *arg, bool
*last,
goto out;
}
- if (root_ht == ht) {
+ if (ht->is_root) {
NL_SET_ERR_MSG_MOD(extack, "Not allowed to delete root node");
return -EINVAL;
}
--
2.11.0
