[PATCH net v3] net/sched: cls_api: add missing validation of netlink attributes

[Davide Caratti]

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 <dcara...@redhat.com>
---
 net/sched/cls_api.c | 13 ++++++++-----
 net/sched/sch_api.c |  8 ++++----
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 0a75cb2e5e7b..70f144ac5e1d 100644
--- 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);
 
@@ -1211,7 +1213,7 @@ static int tc_new_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
 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;
 
@@ -1360,7 +1362,7 @@ static int tc_del_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
        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;
 
@@ -1475,7 +1477,7 @@ static int tc_get_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
        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;
 
@@ -1838,7 +1840,7 @@ static int tc_ctl_chain(struct sk_buff *skb, struct 
nlmsghdr *n,
                return -EPERM;
 
 replay:
-       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;
 
@@ -1949,7 +1951,8 @@ static int tc_dump_chain(struct sk_buff *skb, struct 
netlink_callback *cb)
        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;
 
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 85e73f48e48f..6684641ea344 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1307,10 +1307,6 @@ check_loop_fn(struct Qdisc *q, unsigned long cl, struct 
qdisc_walker *w)
        return 0;
 }
 
-/*
- * Delete/get qdisc.
- */
-
 const struct nla_policy rtm_tca_policy[TCA_MAX + 1] = {
        [TCA_KIND]              = { .type = NLA_STRING },
        [TCA_OPTIONS]           = { .type = NLA_NESTED },
@@ -1323,6 +1319,10 @@ const struct nla_policy rtm_tca_policy[TCA_MAX + 1] = {
        [TCA_EGRESS_BLOCK]      = { .type = NLA_U32 },
 };
 
+/*
+ * Delete/get qdisc.
+ */
+
 static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
                        struct netlink_ext_ack *extack)
 {
-- 
2.17.1