[PATCH] netfilter: ctmark: Fix data-races around ctmark

From: Daniel Xu
Date: Wed Nov 09 2022 - 11:47:19 EST

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@xxxxxxxxx>
---
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