[PATCH 4.18 130/150] net/sched: cls_api: add missing validation of netlink attributes

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Davide Caratti <dcaratti@xxxxxxxxxx>

[ Upstream commit e331473fee3d500bb0d2582a1fe598df3326d8cd ]

Similarly to what has been done in 8b4c3cdd9dd8 ("net: sched: Add policy
validation for tc attributes"), fix classifier code to add validation of
TCA_CHAIN and TCA_KIND netlink attributes.

tested with:
 # ./tdc.py -c filter

v2: Let sch_api and cls_api share nla_policy they have in common, thanks
    to David Ahern.
v3: Avoid EXPORT_SYMBOL(), as validation of those attributes is not done
    by TC modules, thanks to Cong Wang.
    While at it, restore the 'Delete / get qdisc' comment to its orginal
    position, just above tc_get_qdisc() function prototype.

Fixes: 5bc1701881e39 ("net: sched: introduce multichain support for filters")
Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/sched/cls_api.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -31,6 +31,8 @@
 #include <net/pkt_sched.h>
 #include <net/pkt_cls.h>
 
+extern const struct nla_policy rtm_tca_policy[TCA_MAX + 1];
+
 /* The list of all installed classifier types */
 static LIST_HEAD(tcf_proto_base);
 
@@ -1083,7 +1085,7 @@ static int tc_new_tfilter(struct sk_buff
 replay:
 	tp_created = 0;
 
-	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL, extack);
+	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, rtm_tca_policy, extack);
 	if (err < 0)
 		return err;
 
@@ -1226,7 +1228,7 @@ static int tc_del_tfilter(struct sk_buff
 	if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
-	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL, extack);
+	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, rtm_tca_policy, extack);
 	if (err < 0)
 		return err;
 
@@ -1334,7 +1336,7 @@ static int tc_get_tfilter(struct sk_buff
 	void *fh = NULL;
 	int err;
 
-	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL, extack);
+	err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, rtm_tca_policy, extack);
 	if (err < 0)
 		return err;
 
@@ -1488,7 +1490,8 @@ static int tc_dump_tfilter(struct sk_buf
 	if (nlmsg_len(cb->nlh) < sizeof(*tcm))
 		return skb->len;
 
-	err = nlmsg_parse(cb->nlh, sizeof(*tcm), tca, TCA_MAX, NULL, NULL);
+	err = nlmsg_parse(cb->nlh, sizeof(*tcm), tca, TCA_MAX, rtm_tca_policy,
+			  NULL);
 	if (err)
 		return err;