net: fib_rules: annotate data-races around rule->[io]ifindex

rule->iifindex and rule->oifindex can be read without holding RTNL.

Add READ_ONCE()/WRITE_ONCE() annotations where needed.

Fixes: 32affa5578f0 ("fib: rules: no longer hold RTNL in fib_nl_dumprule()")
Signed-off-by: Eric Dumazet <[email protected]>
Reviewed-by: Kuniyuki Iwashima <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index e684ba3ebb38563abefc034c16ba381635285953..94a7872ab231855dd9965efb099c09fe3728e1a2 100644 (file)
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -37,8 +37,8 @@ static const struct fib_kuid_range fib_kuid_range_unset = {
 
 bool fib_rule_matchall(const struct fib_rule *rule)
 {
-       if (rule->iifindex || rule->oifindex || rule->mark || rule->tun_id ||
-           rule->flags)
+       if (READ_ONCE(rule->iifindex) || READ_ONCE(rule->oifindex) ||
+           rule->mark || rule->tun_id || rule->flags)
                return false;
        if (rule->suppress_ifgroup != -1 || rule->suppress_prefixlen != -1)
                return false;
@@ -261,12 +261,14 @@ static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
                          struct flowi *fl, int flags,
                          struct fib_lookup_arg *arg)
 {
-       int ret = 0;
+       int iifindex, oifindex, ret = 0;
 
-       if (rule->iifindex && (rule->iifindex != fl->flowi_iif))
+       iifindex = READ_ONCE(rule->iifindex);
+       if (iifindex && (iifindex != fl->flowi_iif))
                goto out;
 
-       if (rule->oifindex && (rule->oifindex != fl->flowi_oif))
+       oifindex = READ_ONCE(rule->oifindex);
+       if (oifindex && (oifindex != fl->flowi_oif))
                goto out;
 
        if ((rule->mark ^ fl->flowi_mark) & rule->mark_mask)
@@ -1041,14 +1043,14 @@ static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
        if (rule->iifname[0]) {
                if (nla_put_string(skb, FRA_IIFNAME, rule->iifname))
                        goto nla_put_failure;
-               if (rule->iifindex == -1)
+               if (READ_ONCE(rule->iifindex) == -1)
                        frh->flags |= FIB_RULE_IIF_DETACHED;
        }
 
        if (rule->oifname[0]) {
                if (nla_put_string(skb, FRA_OIFNAME, rule->oifname))
                        goto nla_put_failure;
-               if (rule->oifindex == -1)
+               if (READ_ONCE(rule->oifindex) == -1)
                        frh->flags |= FIB_RULE_OIF_DETACHED;
        }
 
@@ -1220,10 +1222,10 @@ static void attach_rules(struct list_head *rules, struct net_device *dev)
        list_for_each_entry(rule, rules, list) {
                if (rule->iifindex == -1 &&
                    strcmp(dev->name, rule->iifname) == 0)
-                       rule->iifindex = dev->ifindex;
+                       WRITE_ONCE(rule->iifindex, dev->ifindex);
                if (rule->oifindex == -1 &&
                    strcmp(dev->name, rule->oifname) == 0)
-                       rule->oifindex = dev->ifindex;
+                       WRITE_ONCE(rule->oifindex, dev->ifindex);
        }
 }
 
@@ -1233,9 +1235,9 @@ static void detach_rules(struct list_head *rules, struct net_device *dev)
 
        list_for_each_entry(rule, rules, list) {
                if (rule->iifindex == dev->ifindex)
-                       rule->iifindex = -1;
+                       WRITE_ONCE(rule->iifindex, -1);
                if (rule->oifindex == dev->ifindex)
-                       rule->oifindex = -1;
+                       WRITE_ONCE(rule->oifindex, -1);
        }
 }