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From:   Daniel Xu <dxu@dxuuu.xyz>
To:     pablo@netfilter.org, fw@strlen.de, kadlec@netfilter.org,
        netfilter-devel@vger.kernel.org
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] netfilter: ctmark: Fix data-races around ctmark
Date:   Wed,  9 Nov 2022 09:46:50 -0700
Message-Id: <22e34710c6e22acc1139b8f8d0a8bd78cf5b64e5.1668012222.git.dxu@dxuuu.xyz>
MIME-Version: 1.0
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Precedence: bulk

nf_conn:mark can be read from and written to in parallel. Use
READ_ONCE()/WRITE_ONCE() for reads and writes to prevent unwanted
compiler optimizations.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
---
 net/core/flow_dissector.c               |  2 +-
 net/ipv4/netfilter/ipt_CLUSTERIP.c      |  4 ++--
 net/netfilter/nf_conntrack_core.c       |  2 +-
 net/netfilter/nf_conntrack_netlink.c    | 24 ++++++++++++++----------
 net/netfilter/nf_conntrack_standalone.c |  2 +-
 net/netfilter/nft_ct.c                  |  6 +++---
 net/netfilter/xt_connmark.c             | 18 ++++++++++--------
 net/openvswitch/conntrack.c             |  8 ++++----
 net/sched/act_connmark.c                |  4 ++--
 net/sched/act_ct.c                      |  8 ++++----
 net/sched/act_ctinfo.c                  |  6 +++---
 11 files changed, 45 insertions(+), 39 deletions(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 25cd35f5922e..007730412947 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -296,7 +296,7 @@ skb_flow_dissect_ct(const struct sk_buff *skb,
 	key->ct_zone = ct->zone.id;
 #endif
 #if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
-	key->ct_mark = ct->mark;
+	key->ct_mark = READ_ONCE(ct->mark);
 #endif
 
 	cl = nf_ct_labels_find(ct);
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index f8e176c77d1c..b3cc416ed292 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -435,7 +435,7 @@ clusterip_tg(struct sk_buff *skb, const struct xt_action_param *par)
 
 	switch (ctinfo) {
 	case IP_CT_NEW:
-		ct->mark = hash;
+		WRITE_ONCE(ct->mark, hash);
 		break;
 	case IP_CT_RELATED:
 	case IP_CT_RELATED_REPLY:
@@ -452,7 +452,7 @@ clusterip_tg(struct sk_buff *skb, const struct xt_action_param *par)
 #ifdef DEBUG
 	nf_ct_dump_tuple_ip(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 #endif
-	pr_debug("hash=%u ct_hash=%u ", hash, ct->mark);
+	pr_debug("hash=%u ct_hash=%u ", hash, READ_ONCE(ct->mark));
 	if (!clusterip_responsible(cipinfo->config, hash)) {
 		pr_debug("not responsible\n");
 		return NF_DROP;
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index f97bda06d2a9..669561fb73bd 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1781,7 +1781,7 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
 			}
 
 #ifdef CONFIG_NF_CONNTRACK_MARK
-			ct->mark = exp->master->mark;
+			WRITE_ONCE(ct->mark, READ_ONCE(exp->master->mark));
 #endif
 #ifdef CONFIG_NF_CONNTRACK_SECMARK
 			ct->secmark = exp->master->secmark;
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 7562b215b932..242b7e2a8b03 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -328,9 +328,9 @@ ctnetlink_dump_timestamp(struct sk_buff *skb, const struct nf_conn *ct)
 }
 
 #ifdef CONFIG_NF_CONNTRACK_MARK
-static int ctnetlink_dump_mark(struct sk_buff *skb, const struct nf_conn *ct)
+static int ctnetlink_dump_mark(struct sk_buff *skb, u32 mark)
 {
-	if (nla_put_be32(skb, CTA_MARK, htonl(ct->mark)))
+	if (nla_put_be32(skb, CTA_MARK, htonl(mark)))
 		goto nla_put_failure;
 	return 0;
 
@@ -543,7 +543,7 @@ static int ctnetlink_dump_extinfo(struct sk_buff *skb,
 static int ctnetlink_dump_info(struct sk_buff *skb, struct nf_conn *ct)
 {
 	if (ctnetlink_dump_status(skb, ct) < 0 ||
-	    ctnetlink_dump_mark(skb, ct) < 0 ||
+	    ctnetlink_dump_mark(skb, READ_ONCE(ct->mark)) < 0 ||
 	    ctnetlink_dump_secctx(skb, ct) < 0 ||
 	    ctnetlink_dump_id(skb, ct) < 0 ||
 	    ctnetlink_dump_use(skb, ct) < 0 ||
@@ -722,6 +722,7 @@ ctnetlink_conntrack_event(unsigned int events, const struct nf_ct_event *item)
 	struct sk_buff *skb;
 	unsigned int type;
 	unsigned int flags = 0, group;
+	u32 mark;
 	int err;
 
 	if (events & (1 << IPCT_DESTROY)) {
@@ -826,8 +827,9 @@ ctnetlink_conntrack_event(unsigned int events, const struct nf_ct_event *item)
 	}
 
 #ifdef CONFIG_NF_CONNTRACK_MARK
-	if ((events & (1 << IPCT_MARK) || ct->mark)
-	    && ctnetlink_dump_mark(skb, ct) < 0)
+	mark = READ_ONCE(ct->mark);
+	if ((events & (1 << IPCT_MARK) || mark)
+	    && ctnetlink_dump_mark(skb, mark) < 0)
 		goto nla_put_failure;
 #endif
 	nlmsg_end(skb, nlh);
@@ -1154,7 +1156,7 @@ static int ctnetlink_filter_match(struct nf_conn *ct, void *data)
 	}
 
 #ifdef CONFIG_NF_CONNTRACK_MARK
-	if ((ct->mark & filter->mark.mask) != filter->mark.val)
+	if ((READ_ONCE(ct->mark) & filter->mark.mask) != filter->mark.val)
 		goto ignore_entry;
 #endif
 	status = (u32)READ_ONCE(ct->status);
@@ -2002,9 +2004,9 @@ static void ctnetlink_change_mark(struct nf_conn *ct,
 		mask = ~ntohl(nla_get_be32(cda[CTA_MARK_MASK]));
 
 	mark = ntohl(nla_get_be32(cda[CTA_MARK]));
-	newmark = (ct->mark & mask) ^ mark;
-	if (newmark != ct->mark)
-		ct->mark = newmark;
+	newmark = (READ_ONCE(ct->mark) & mask) ^ mark;
+	if (newmark != READ_ONCE(ct->mark))
+		WRITE_ONCE(ct->mark, newmark);
 }
 #endif
 
@@ -2669,6 +2671,7 @@ static int __ctnetlink_glue_build(struct sk_buff *skb, struct nf_conn *ct)
 {
 	const struct nf_conntrack_zone *zone;
 	struct nlattr *nest_parms;
+	u32 mark;
 
 	zone = nf_ct_zone(ct);
 
@@ -2730,7 +2733,8 @@ static int __ctnetlink_glue_build(struct sk_buff *skb, struct nf_conn *ct)
 		goto nla_put_failure;
 
 #ifdef CONFIG_NF_CONNTRACK_MARK
-	if (ct->mark && ctnetlink_dump_mark(skb, ct) < 0)
+	mark = READ_ONCE(ct->mark);
+	if (mark && ctnetlink_dump_mark(skb, mark) < 0)
 		goto nla_put_failure;
 #endif
 	if (ctnetlink_dump_labels(skb, ct) < 0)
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 4ffe84c5a82c..bca839ab1ae8 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -366,7 +366,7 @@ static int ct_seq_show(struct seq_file *s, void *v)
 		goto release;
 
 #if defined(CONFIG_NF_CONNTRACK_MARK)
-	seq_printf(s, "mark=%u ", ct->mark);
+	seq_printf(s, "mark=%u ", READ_ONCE(ct->mark));
 #endif
 
 	ct_show_secctx(s, ct);
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index a3f01f209a53..641dc21f92b4 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -98,7 +98,7 @@ static void nft_ct_get_eval(const struct nft_expr *expr,
 		return;
 #ifdef CONFIG_NF_CONNTRACK_MARK
 	case NFT_CT_MARK:
-		*dest = ct->mark;
+		*dest = READ_ONCE(ct->mark);
 		return;
 #endif
 #ifdef CONFIG_NF_CONNTRACK_SECMARK
@@ -297,8 +297,8 @@ static void nft_ct_set_eval(const struct nft_expr *expr,
 	switch (priv->key) {
 #ifdef CONFIG_NF_CONNTRACK_MARK
 	case NFT_CT_MARK:
-		if (ct->mark != value) {
-			ct->mark = value;
+		if (READ_ONCE(ct->mark) != value) {
+			WRITE_ONCE(ct->mark, value);
 			nf_conntrack_event_cache(IPCT_MARK, ct);
 		}
 		break;
diff --git a/net/netfilter/xt_connmark.c b/net/netfilter/xt_connmark.c
index e5ebc0810675..ad3c033db64e 100644
--- a/net/netfilter/xt_connmark.c
+++ b/net/netfilter/xt_connmark.c
@@ -30,6 +30,7 @@ connmark_tg_shift(struct sk_buff *skb, const struct xt_connmark_tginfo2 *info)
 	u_int32_t new_targetmark;
 	struct nf_conn *ct;
 	u_int32_t newmark;
+	u_int32_t oldmark;
 
 	ct = nf_ct_get(skb, &ctinfo);
 	if (ct == NULL)
@@ -37,14 +38,15 @@ connmark_tg_shift(struct sk_buff *skb, const struct xt_connmark_tginfo2 *info)
 
 	switch (info->mode) {
 	case XT_CONNMARK_SET:
-		newmark = (ct->mark & ~info->ctmask) ^ info->ctmark;
+		oldmark = READ_ONCE(ct->mark);
+		newmark = (oldmark & ~info->ctmask) ^ info->ctmark;
 		if (info->shift_dir == D_SHIFT_RIGHT)
 			newmark >>= info->shift_bits;
 		else
 			newmark <<= info->shift_bits;
 
-		if (ct->mark != newmark) {
-			ct->mark = newmark;
+		if (READ_ONCE(ct->mark) != newmark) {
+			WRITE_ONCE(ct->mark, newmark);
 			nf_conntrack_event_cache(IPCT_MARK, ct);
 		}
 		break;
@@ -55,15 +57,15 @@ connmark_tg_shift(struct sk_buff *skb, const struct xt_connmark_tginfo2 *info)
 		else
 			new_targetmark <<= info->shift_bits;
 
-		newmark = (ct->mark & ~info->ctmask) ^
+		newmark = (READ_ONCE(ct->mark) & ~info->ctmask) ^
 			  new_targetmark;
-		if (ct->mark != newmark) {
-			ct->mark = newmark;
+		if (READ_ONCE(ct->mark) != newmark) {
+			WRITE_ONCE(ct->mark, newmark);
 			nf_conntrack_event_cache(IPCT_MARK, ct);
 		}
 		break;
 	case XT_CONNMARK_RESTORE:
-		new_targetmark = (ct->mark & info->ctmask);
+		new_targetmark = (READ_ONCE(ct->mark) & info->ctmask);
 		if (info->shift_dir == D_SHIFT_RIGHT)
 			new_targetmark >>= info->shift_bits;
 		else
@@ -126,7 +128,7 @@ connmark_mt(const struct sk_buff *skb, struct xt_action_param *par)
 	if (ct == NULL)
 		return false;
 
-	return ((ct->mark & info->mask) == info->mark) ^ info->invert;
+	return ((READ_ONCE(ct->mark) & info->mask) == info->mark) ^ info->invert;
 }
 
 static int connmark_mt_check(const struct xt_mtchk_param *par)
diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index c7b10234cf7c..c8eaf4234b2e 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -152,7 +152,7 @@ static u8 ovs_ct_get_state(enum ip_conntrack_info ctinfo)
 static u32 ovs_ct_get_mark(const struct nf_conn *ct)
 {
 #if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
-	return ct ? ct->mark : 0;
+	return ct ? READ_ONCE(ct->mark) : 0;
 #else
 	return 0;
 #endif
@@ -340,9 +340,9 @@ static int ovs_ct_set_mark(struct nf_conn *ct, struct sw_flow_key *key,
 #if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
 	u32 new_mark;
 
-	new_mark = ct_mark | (ct->mark & ~(mask));
-	if (ct->mark != new_mark) {
-		ct->mark = new_mark;
+	new_mark = ct_mark | (READ_ONCE(ct->mark) & ~(mask));
+	if (READ_ONCE(ct->mark) != new_mark) {
+		WRITE_ONCE(ct->mark, new_mark);
 		if (nf_ct_is_confirmed(ct))
 			nf_conntrack_event_cache(IPCT_MARK, ct);
 		key->ct.mark = new_mark;
diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
index 66b143bb04ac..d41002e4613f 100644
--- a/net/sched/act_connmark.c
+++ b/net/sched/act_connmark.c
@@ -61,7 +61,7 @@ static int tcf_connmark_act(struct sk_buff *skb, const struct tc_action *a,
 
 	c = nf_ct_get(skb, &ctinfo);
 	if (c) {
-		skb->mark = c->mark;
+		skb->mark = READ_ONCE(c->mark);
 		/* using overlimits stats to count how many packets marked */
 		ca->tcf_qstats.overlimits++;
 		goto out;
@@ -81,7 +81,7 @@ static int tcf_connmark_act(struct sk_buff *skb, const struct tc_action *a,
 	c = nf_ct_tuplehash_to_ctrack(thash);
 	/* using overlimits stats to count how many packets marked */
 	ca->tcf_qstats.overlimits++;
-	skb->mark = c->mark;
+	skb->mark = READ_ONCE(c->mark);
 	nf_ct_put(c);
 
 out:
diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index b38d91d6b249..4c7f7861ea96 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -178,7 +178,7 @@ static void tcf_ct_flow_table_add_action_meta(struct nf_conn *ct,
 	entry = tcf_ct_flow_table_flow_action_get_next(action);
 	entry->id = FLOW_ACTION_CT_METADATA;
 #if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
-	entry->ct_metadata.mark = ct->mark;
+	entry->ct_metadata.mark = READ_ONCE(ct->mark);
 #endif
 	ctinfo = dir == IP_CT_DIR_ORIGINAL ? IP_CT_ESTABLISHED :
 					     IP_CT_ESTABLISHED_REPLY;
@@ -936,9 +936,9 @@ static void tcf_ct_act_set_mark(struct nf_conn *ct, u32 mark, u32 mask)
 	if (!mask)
 		return;
 
-	new_mark = mark | (ct->mark & ~(mask));
-	if (ct->mark != new_mark) {
-		ct->mark = new_mark;
+	new_mark = mark | (READ_ONCE(ct->mark) & ~(mask));
+	if (READ_ONCE(ct->mark) != new_mark) {
+		WRITE_ONCE(ct->mark, new_mark);
 		if (nf_ct_is_confirmed(ct))
 			nf_conntrack_event_cache(IPCT_MARK, ct);
 	}
diff --git a/net/sched/act_ctinfo.c b/net/sched/act_ctinfo.c
index d4102f0a9abd..eaa02f098d1c 100644
--- a/net/sched/act_ctinfo.c
+++ b/net/sched/act_ctinfo.c
@@ -32,7 +32,7 @@ static void tcf_ctinfo_dscp_set(struct nf_conn *ct, struct tcf_ctinfo *ca,
 {
 	u8 dscp, newdscp;
 
-	newdscp = (((ct->mark & cp->dscpmask) >> cp->dscpmaskshift) << 2) &
+	newdscp = (((READ_ONCE(ct->mark) & cp->dscpmask) >> cp->dscpmaskshift) << 2) &
 		     ~INET_ECN_MASK;
 
 	switch (proto) {
@@ -72,7 +72,7 @@ static void tcf_ctinfo_cpmark_set(struct nf_conn *ct, struct tcf_ctinfo *ca,
 				  struct sk_buff *skb)
 {
 	ca->stats_cpmark_set++;
-	skb->mark = ct->mark & cp->cpmarkmask;
+	skb->mark = READ_ONCE(ct->mark) & cp->cpmarkmask;
 }
 
 static int tcf_ctinfo_act(struct sk_buff *skb, const struct tc_action *a,
@@ -130,7 +130,7 @@ static int tcf_ctinfo_act(struct sk_buff *skb, const struct tc_action *a,
 	}
 
 	if (cp->mode & CTINFO_MODE_DSCP)
-		if (!cp->dscpstatemask || (ct->mark & cp->dscpstatemask))
+		if (!cp->dscpstatemask || (READ_ONCE(ct->mark) & cp->dscpstatemask))
 			tcf_ctinfo_dscp_set(ct, ca, cp, skb, wlen, proto);
 
 	if (cp->mode & CTINFO_MODE_CPMARK)
-- 
2.38.1