From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1ABFE4FDA69; Tue, 13 Oct 2026 12:12:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893578; cv=none; b=mGdSK5WXNS3tCWMxZiW/6pVZwgt6l1iyK6clvJGb+iwqxP9zEa5lmAGGy5/y7P4M1YDd4AhN8UL7MWYgsLNWighOzHAp8hdxcJW+6MekzLyXPrPKNBfMFJHKqOMo6r69LtEhlCFyz2DT9D6lZiMthPyD7jynptS8IpfC8irAWCw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791893578; c=relaxed/simple; bh=NcwDaVX4yUrZbZ1OOAXatidwDevk7xgA3XjhvPCsXxQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BBnviPHmAGfXHWm9+ESjgUfYVNDBajyqxHMi+4sMh2T0pourshgqx/2/7iBsZtQn1+RaCmZHrPhiazu2i+Hx1gXV6tS+tD5ZzsuzGdrJDA3qJR9FzUMTu5F+1icgluWIUqaXUgbd+iOTTtTnELMgnUmpPAXSAj/qiBtoElQqUMw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=QbfafwSh; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="QbfafwSh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 785711F000FF; Tue, 13 Oct 2026 12:12:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791893577; bh=jpbUHCF+0Fw6veEo2EyywKid28Ze/ZzmnWtKx97FwPk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QbfafwShrisxLylVauX3PFF1+ZOwki9gXtuxU2GG+xZtiljH+VvCMhuvShDFmLk9r ZOTHSa2pyT+MiimkdagecpxivS9FDsZhjHdEwkomCZ3R2BsDVt791G2qPk89JP5Owx bKIhqr2g32aLkZiYTeUEzlb3O3/okdiMiYzZLuvk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Victor Nogueira , Jamal Hadi Salim , Daniel Borkmann , Sebastian Andrzej Siewior , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 272/621] net/sched: Handle TC_ACT_REDIRECT from qdisc filter chains Date: Tue, 13 Oct 2026 13:34:27 +0200 Message-ID: <20261013112927.315328586@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112920.855194808@linuxfoundation.org> References: <20261013112920.855194808@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jamal Hadi Salim [ Upstream commit ec48b3be2c8595dd290be883dbd4fb8b2f9f5d5e ] When a TC filter attached to a qdisc filter chain returns TC_ACT_REDIRECT (ex: via an eBPF program calling bpf_redirect() or an act_bpf action), the redirect was silently lost i.e no qdisc classify function handled TC_ACT_REDIRECT, so the packet fell through the switch and was enqueued normally instead of being redirected. This has been broken since bpf_redirect() was introduced for TC in commit 27b29f63058d ("bpf: add bpf_redirect() helper"). We got lucky for a long time because bpf_net_context was a per-CPU variable that was always available. commit 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") turned bpf_net_context into a task_struct member that is only set up by explicit callers. Without a caller setting it up, bpf_redirect() itself crashes with a NULL pointer dereference in bpf_net_ctx_get_ri(). However, even with bpf_net_context available, TC_ACT_REDIRECT from qdisc filter chains cannot be honored without adding skb_do_redirect() calls to every qdisc classify function, which would require changes across net/sched/. Isolate it to ebpf core where it belongs. Instead, add a tcf_classify_qdisc() inline helper in pkt_cls.h, as a wrapper around tcf_classify() for use by qdisc classify functions and tcf_qevent_handle(). When the classify verdict is TC_ACT_REDIRECT, the wrapper converts it to TC_ACT_SHOT, dropping the packet rather than letting it continue silently. Dropping is preferred over letting the packet through because the user immediately sees packet loss. Silently passing the packet through would hide the problem and leave the user wondering why their redirect is not working. The clsact fast path, tc_run() continues to call tcf_classify() directly and is unaffected: TC_ACT_REDIRECT is returned as-is and handled by sch_handle_egress/ingress() calling skb_do_redirect() as before. Fixes: 27b29f63058d ("bpf: add bpf_redirect() helper") Fixes: 401cb7dae813 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.") Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Signed-off-by: Daniel Borkmann Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260706185609.330006-3-daniel@iogearbox.net Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/pkt_cls.h | 14 +++++++++++++- net/sched/cls_api.c | 4 +--- net/sched/sch_cake.c | 2 +- net/sched/sch_drr.c | 2 +- net/sched/sch_dualpi2.c | 2 +- net/sched/sch_ets.c | 2 +- net/sched/sch_fq_codel.c | 2 +- net/sched/sch_fq_pie.c | 2 +- net/sched/sch_hfsc.c | 2 +- net/sched/sch_htb.c | 2 +- net/sched/sch_multiq.c | 2 +- net/sched/sch_prio.c | 2 +- net/sched/sch_qfq.c | 2 +- net/sched/sch_sfb.c | 2 +- net/sched/sch_sfq.c | 2 +- 15 files changed, 27 insertions(+), 17 deletions(-) diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h index 99ac747b79060..7f0c422307f45 100644 --- a/include/net/pkt_cls.h +++ b/include/net/pkt_cls.h @@ -156,8 +156,20 @@ static inline int tcf_classify(struct sk_buff *skb, { return TC_ACT_UNSPEC; } - #endif +static inline int tcf_classify_qdisc(struct sk_buff *skb, + const struct tcf_proto *tp, + struct tcf_result *res, bool compat_mode) +{ + int ret = tcf_classify(skb, NULL, tp, res, compat_mode); + + /* TC_ACT_REDIRECT from qdisc filter chains is not supported. + * Use BPF via tcx or mirred redirect instead. + */ + if (unlikely(ret == TC_ACT_REDIRECT)) + ret = TC_ACT_SHOT; + return ret; +} static inline unsigned long __cls_set_class(unsigned long *clp, unsigned long cl) diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 0bc0c010434cb..e56de2d3dc102 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -4082,9 +4082,7 @@ struct sk_buff *tcf_qevent_handle(struct tcf_qevent *qe, struct Qdisc *sch, stru fl = rcu_dereference_bh(qe->filter_chain); - switch (tcf_classify(skb, NULL, fl, &cl_res, false)) { - case TC_ACT_REDIRECT: - fallthrough; + switch (tcf_classify_qdisc(skb, fl, &cl_res, false)) { case TC_ACT_SHOT: qdisc_qstats_drop(sch); __qdisc_drop(skb, to_free); diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c index 8ed8ac120693d..0e7007c545e8a 100644 --- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -1709,7 +1709,7 @@ static u32 cake_classify(struct Qdisc *sch, struct cake_tin_data **t, goto hash; *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; - result = tcf_classify(skb, NULL, filter, &res, false); + result = tcf_classify_qdisc(skb, filter, &res, false); if (result >= 0) { #ifdef CONFIG_NET_CLS_ACT diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c index ba802db279932..8035ffeef2e92 100644 --- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -313,7 +313,7 @@ static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch, *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; fl = rcu_dereference_bh(q->filter_list); - result = tcf_classify(skb, NULL, fl, &res, false); + result = tcf_classify_qdisc(skb, fl, &res, false); if (result >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { diff --git a/net/sched/sch_dualpi2.c b/net/sched/sch_dualpi2.c index 4ee841f7a94d4..4642549f2f524 100644 --- a/net/sched/sch_dualpi2.c +++ b/net/sched/sch_dualpi2.c @@ -367,7 +367,7 @@ static int dualpi2_skb_classify(struct dualpi2_sched_data *q, if (!fl) return NET_XMIT_SUCCESS; - result = tcf_classify(skb, NULL, fl, &res, false); + result = tcf_classify_qdisc(skb, fl, &res, false); if (result >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { diff --git a/net/sched/sch_ets.c b/net/sched/sch_ets.c index 27e549646dee1..03f5bb812a274 100644 --- a/net/sched/sch_ets.c +++ b/net/sched/sch_ets.c @@ -389,7 +389,7 @@ static struct ets_class *ets_classify(struct sk_buff *skb, struct Qdisc *sch, *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; if (TC_H_MAJ(skb->priority) != sch->handle) { fl = rcu_dereference_bh(q->filter_list); - err = tcf_classify(skb, NULL, fl, &res, false); + err = tcf_classify_qdisc(skb, fl, &res, false); #ifdef CONFIG_NET_CLS_ACT switch (err) { case TC_ACT_STOLEN: diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c index c135b1dd5972b..4d32fd90f590a 100644 --- a/net/sched/sch_fq_codel.c +++ b/net/sched/sch_fq_codel.c @@ -91,7 +91,7 @@ static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch, return fq_codel_hash(q, skb) + 1; *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; - result = tcf_classify(skb, NULL, filter, &res, false); + result = tcf_classify_qdisc(skb, filter, &res, false); if (result >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c index ff26999afe4c6..0d09c7e9f7549 100644 --- a/net/sched/sch_fq_pie.c +++ b/net/sched/sch_fq_pie.c @@ -96,7 +96,7 @@ static unsigned int fq_pie_classify(struct sk_buff *skb, struct Qdisc *sch, return fq_pie_hash(q, skb) + 1; *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; - result = tcf_classify(skb, NULL, filter, &res, false); + result = tcf_classify_qdisc(skb, filter, &res, false); if (result >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c index df3501dfe01a8..b7c7121c36114 100644 --- a/net/sched/sch_hfsc.c +++ b/net/sched/sch_hfsc.c @@ -1154,7 +1154,7 @@ hfsc_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr) head = &q->root; drift = HFSC_CLASSIFY_MAX_DRIFT; tcf = rcu_dereference_bh(q->root.filter_list); - while (tcf && (result = tcf_classify(skb, NULL, tcf, &res, false)) >= 0) { + while (tcf && (result = tcf_classify_qdisc(skb, tcf, &res, false)) >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { case TC_ACT_QUEUED: diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index fc8c540393433..ae1bb2834c744 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -243,7 +243,7 @@ static struct htb_class *htb_classify(struct sk_buff *skb, struct Qdisc *sch, } *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; - while (tcf && (result = tcf_classify(skb, NULL, tcf, &res, false)) >= 0) { + while (tcf && (result = tcf_classify_qdisc(skb, tcf, &res, false)) >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { case TC_ACT_QUEUED: diff --git a/net/sched/sch_multiq.c b/net/sched/sch_multiq.c index e50a37b7cec1a..7962fc0292a5e 100644 --- a/net/sched/sch_multiq.c +++ b/net/sched/sch_multiq.c @@ -36,7 +36,7 @@ multiq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr) int err; *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; - err = tcf_classify(skb, NULL, fl, &res, false); + err = tcf_classify_qdisc(skb, fl, &res, false); #ifdef CONFIG_NET_CLS_ACT switch (err) { case TC_ACT_STOLEN: diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c index 9e2b9a490db23..6f4388cf10488 100644 --- a/net/sched/sch_prio.c +++ b/net/sched/sch_prio.c @@ -39,7 +39,7 @@ prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr) *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; if (TC_H_MAJ(skb->priority) != sch->handle) { fl = rcu_dereference_bh(q->filter_list); - err = tcf_classify(skb, NULL, fl, &res, false); + err = tcf_classify_qdisc(skb, fl, &res, false); #ifdef CONFIG_NET_CLS_ACT switch (err) { case TC_ACT_STOLEN: diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index f94c9c9c90424..7d93690cb4360 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -709,7 +709,7 @@ static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch, *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; fl = rcu_dereference_bh(q->filter_list); - result = tcf_classify(skb, NULL, fl, &res, false); + result = tcf_classify_qdisc(skb, fl, &res, false); if (result >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c index 14ac889778475..1b326b459ce9b 100644 --- a/net/sched/sch_sfb.c +++ b/net/sched/sch_sfb.c @@ -260,7 +260,7 @@ static bool sfb_classify(struct sk_buff *skb, struct tcf_proto *fl, struct tcf_result res; int result; - result = tcf_classify(skb, NULL, fl, &res, false); + result = tcf_classify_qdisc(skb, fl, &res, false); if (result >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index d11b0b192e2c2..123c0d199b0bf 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -171,7 +171,7 @@ static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch, return sfq_hash(q, skb) + 1; *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; - result = tcf_classify(skb, NULL, fl, &res, false); + result = tcf_classify_qdisc(skb, fl, &res, false); if (result >= 0) { #ifdef CONFIG_NET_CLS_ACT switch (result) { -- 2.53.0