Commit a58f00ed authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Paolo Abeni
Browse files

net: sched: cls_api: improve the error message for ID allocation failure 



We run into an exhaustion problem with the kernel-allocated filter IDs.
Our allocation problem can be fixed on the user space side,
but the error message in this case was quite misleading:

  "Filter with specified priority/protocol not found" (EINVAL)

Specifically when we can't allocate a _new_ ID because filter with
lowest ID already _exists_, saying "filter not found", is confusing.

Kernel allocates IDs in range of 0xc0000 -> 0x8000, giving out ID one
lower than lowest existing in that range. The error message makes sense
when tcf_chain_tp_find() gets called for GET and DEL but for NEW we
need to provide more specific error messages for all three cases:

 - user wants the ID to be auto-allocated but filter with ID 0x8000
   already exists

 - filter already exists and can be replaced, but user asked
   for a protocol change

 - filter doesn't exist

Caller of tcf_chain_tp_insert_unique() doesn't set extack today,
so don't bother plumbing it in.

Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Acked-by: default avatarJamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20241108010254.2995438-1-kuba@kernel.org


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 12079a59

net/sched/cls_api.c

+25 −14
Original line number Diff line number Diff line
@@ -1933,7 +1933,8 @@ static void tcf_chain_tp_remove(struct tcf_chain *chain, 
static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,

					   struct tcf_chain_info *chain_info,

					   u32 protocol, u32 prio,

					   bool prio_allocate);

					   bool prio_allocate,

					   struct netlink_ext_ack *extack);



/* Try to insert new proto.

 * If proto with specified priority already exists, free new proto
@@ -1957,8 +1958,7 @@ static struct tcf_proto *tcf_chain_tp_insert_unique(struct tcf_chain *chain, 
		return ERR_PTR(-EAGAIN);

	}



	tp = tcf_chain_tp_find(chain, &chain_info,

			       protocol, prio, false);

	tp = tcf_chain_tp_find(chain, &chain_info, protocol, prio, false, NULL);

	if (!tp)

		err = tcf_chain_tp_insert(chain, &chain_info, tp_new);

	mutex_unlock(&chain->filter_chain_lock);
@@ -2018,7 +2018,8 @@ static void tcf_chain_tp_delete_empty(struct tcf_chain *chain, 
static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain,

					   struct tcf_chain_info *chain_info,

					   u32 protocol, u32 prio,

					   bool prio_allocate)

					   bool prio_allocate,

					   struct netlink_ext_ack *extack)

{

	struct tcf_proto **pprev;

	struct tcf_proto *tp;
@@ -2029,9 +2030,14 @@ static struct tcf_proto *tcf_chain_tp_find(struct tcf_chain *chain, 
	     pprev = &tp->next) {

		if (tp->prio >= prio) {

			if (tp->prio == prio) {

				if (prio_allocate ||

				    (tp->protocol != protocol && protocol))

				if (prio_allocate) {

					NL_SET_ERR_MSG(extack, "Lowest ID from auto-alloc range already in use");

					return ERR_PTR(-ENOSPC);

				}

				if (tp->protocol != protocol && protocol) {

					NL_SET_ERR_MSG(extack, "Protocol mismatch for filter with specified priority");

					return ERR_PTR(-EINVAL);

				}

			} else {

				tp = NULL;

			}
@@ -2312,9 +2318,8 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n, 


	mutex_lock(&chain->filter_chain_lock);

	tp = tcf_chain_tp_find(chain, &chain_info, protocol,

			       prio, prio_allocate);

			       prio, prio_allocate, extack);

	if (IS_ERR(tp)) {

		NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");

		err = PTR_ERR(tp);

		goto errout_locked;

	}
@@ -2539,10 +2544,13 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n, 


	mutex_lock(&chain->filter_chain_lock);

	tp = tcf_chain_tp_find(chain, &chain_info, protocol,

			       prio, false);

	if (!tp || IS_ERR(tp)) {

			       prio, false, extack);

	if (!tp) {

		err = -ENOENT;

		NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");

		err = tp ? PTR_ERR(tp) : -ENOENT;

		goto errout_locked;

	} else if (IS_ERR(tp)) {

		err = PTR_ERR(tp);

		goto errout_locked;

	} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind)) {

		NL_SET_ERR_MSG(extack, "Specified filter kind does not match existing one");
@@ -2679,11 +2687,14 @@ static int tc_get_tfilter(struct sk_buff *skb, struct nlmsghdr *n, 


	mutex_lock(&chain->filter_chain_lock);

	tp = tcf_chain_tp_find(chain, &chain_info, protocol,

			       prio, false);

			       prio, false, extack);

	mutex_unlock(&chain->filter_chain_lock);

	if (!tp || IS_ERR(tp)) {

	if (!tp) {

		err = -ENOENT;

		NL_SET_ERR_MSG(extack, "Filter with specified priority/protocol not found");

		err = tp ? PTR_ERR(tp) : -ENOENT;

		goto errout;

	} else if (IS_ERR(tp)) {

		err = PTR_ERR(tp);

		goto errout;

	} else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind)) {

		NL_SET_ERR_MSG(extack, "Specified filter kind does not match existing one");