From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file

---
 kernel/net/sched/sch_api.c |   94 +++++++++++++++++++++++++++++++++++------------
 1 files changed, 70 insertions(+), 24 deletions(-)

diff --git a/kernel/net/sched/sch_api.c b/kernel/net/sched/sch_api.c
index d8ffe41..5c2d230 100644
--- a/kernel/net/sched/sch_api.c
+++ b/kernel/net/sched/sch_api.c
@@ -1044,12 +1044,12 @@
 
 	if (parent == NULL) {
 		unsigned int i, num_q, ingress;
+		struct netdev_queue *dev_queue;
 
 		ingress = 0;
 		num_q = dev->num_tx_queues;
 		if ((q && q->flags & TCQ_F_INGRESS) ||
 		    (new && new->flags & TCQ_F_INGRESS)) {
-			num_q = 1;
 			ingress = 1;
 			if (!dev_ingress_queue(dev)) {
 				NL_SET_ERR_MSG(extack, "Device does not have an ingress queue");
@@ -1065,18 +1065,18 @@
 		if (new && new->ops->attach)
 			goto skip;
 
-		for (i = 0; i < num_q; i++) {
-			struct netdev_queue *dev_queue = dev_ingress_queue(dev);
-
-			if (!ingress)
+		if (!ingress) {
+			for (i = 0; i < num_q; i++) {
 				dev_queue = netdev_get_tx_queue(dev, i);
+				old = dev_graft_qdisc(dev_queue, new);
 
-			old = dev_graft_qdisc(dev_queue, new);
-			if (new && i > 0)
-				qdisc_refcount_inc(new);
-
-			if (!ingress)
+				if (new && i > 0)
+					qdisc_refcount_inc(new);
 				qdisc_put(old);
+			}
+		} else {
+			dev_queue = dev_ingress_queue(dev);
+			old = dev_graft_qdisc(dev_queue, new);
 		}
 
 skip:
@@ -1112,6 +1112,11 @@
 		if (!cl) {
 			NL_SET_ERR_MSG(extack, "Specified class not found");
 			return -ENOENT;
+		}
+
+		if (new && new->ops == &noqueue_qdisc_ops) {
+			NL_SET_ERR_MSG(extack, "Cannot assign noqueue to a class");
+			return -EINVAL;
 		}
 
 		err = cops->graft(parent, cl, new, &old, extack);
@@ -1218,7 +1223,12 @@
 	sch->parent = parent;
 
 	if (handle == TC_H_INGRESS) {
-		sch->flags |= TCQ_F_INGRESS;
+		if (!(sch->flags & TCQ_F_INGRESS)) {
+			NL_SET_ERR_MSG(extack,
+				       "Specified parent ID is reserved for ingress and clsact Qdiscs");
+			err = -EINVAL;
+			goto err_out3;
+		}
 		handle = TC_H_MAKE(TC_H_INGRESS, 0);
 	} else {
 		if (handle == 0) {
@@ -1503,10 +1513,28 @@
 	return 0;
 }
 
+static bool req_create_or_replace(struct nlmsghdr *n)
+{
+	return (n->nlmsg_flags & NLM_F_CREATE &&
+		n->nlmsg_flags & NLM_F_REPLACE);
+}
+
+static bool req_create_exclusive(struct nlmsghdr *n)
+{
+	return (n->nlmsg_flags & NLM_F_CREATE &&
+		n->nlmsg_flags & NLM_F_EXCL);
+}
+
+static bool req_change(struct nlmsghdr *n)
+{
+	return (!(n->nlmsg_flags & NLM_F_CREATE) &&
+		!(n->nlmsg_flags & NLM_F_REPLACE) &&
+		!(n->nlmsg_flags & NLM_F_EXCL));
+}
+
 /*
  * Create/change qdisc.
  */
-
 static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 			   struct netlink_ext_ack *extack)
 {
@@ -1579,10 +1607,19 @@
 					NL_SET_ERR_MSG(extack, "Invalid qdisc name");
 					return -EINVAL;
 				}
+				if (q->flags & TCQ_F_INGRESS) {
+					NL_SET_ERR_MSG(extack,
+						       "Cannot regraft ingress or clsact Qdiscs");
+					return -EINVAL;
+				}
 				if (q == p ||
 				    (p && check_loop(q, p, 0))) {
 					NL_SET_ERR_MSG(extack, "Qdisc parent/child loop detected");
 					return -ELOOP;
+				}
+				if (clid == TC_H_INGRESS) {
+					NL_SET_ERR_MSG(extack, "Ingress cannot graft directly");
+					return -EINVAL;
 				}
 				qdisc_refcount_inc(q);
 				goto graft;
@@ -1594,27 +1631,35 @@
 				 *
 				 *   We know, that some child q is already
 				 *   attached to this parent and have choice:
-				 *   either to change it or to create/graft new one.
+				 *   1) change it or 2) create/graft new one.
+				 *   If the requested qdisc kind is different
+				 *   than the existing one, then we choose graft.
+				 *   If they are the same then this is "change"
+				 *   operation - just let it fallthrough..
 				 *
 				 *   1. We are allowed to create/graft only
-				 *   if CREATE and REPLACE flags are set.
+				 *   if the request is explicitly stating
+				 *   "please create if it doesn't exist".
 				 *
-				 *   2. If EXCL is set, requestor wanted to say,
-				 *   that qdisc tcm_handle is not expected
+				 *   2. If the request is to exclusive create
+				 *   then the qdisc tcm_handle is not expected
 				 *   to exist, so that we choose create/graft too.
 				 *
 				 *   3. The last case is when no flags are set.
+				 *   This will happen when for example tc
+				 *   utility issues a "change" command.
 				 *   Alas, it is sort of hole in API, we
 				 *   cannot decide what to do unambiguously.
-				 *   For now we select create/graft, if
-				 *   user gave KIND, which does not match existing.
+				 *   For now we select create/graft.
 				 */
-				if ((n->nlmsg_flags & NLM_F_CREATE) &&
-				    (n->nlmsg_flags & NLM_F_REPLACE) &&
-				    ((n->nlmsg_flags & NLM_F_EXCL) ||
-				     (tca[TCA_KIND] &&
-				      nla_strcmp(tca[TCA_KIND], q->ops->id))))
-					goto create_n_graft;
+				if (tca[TCA_KIND] &&
+				    nla_strcmp(tca[TCA_KIND], q->ops->id)) {
+					if (req_create_or_replace(n) ||
+					    req_create_exclusive(n))
+						goto create_n_graft;
+					else if (req_change(n))
+						goto create_n_graft2;
+				}
 			}
 		}
 	} else {
@@ -1648,6 +1693,7 @@
 		NL_SET_ERR_MSG(extack, "Qdisc not found. To create specify NLM_F_CREATE flag");
 		return -ENOENT;
 	}
+create_n_graft2:
 	if (clid == TC_H_INGRESS) {
 		if (dev_ingress_queue(dev)) {
 			q = qdisc_create(dev, dev_ingress_queue(dev), p,

--
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