cls_bpf: make binding to classid optional

The binding to a particular classid was so far always mandatory for
cls_bpf, but it doesn't need to be. Therefore, lift this restriction
as similarly done in other classifiers.

Only a couple of qdiscs make use of class from the tcf_result, others
don't strictly care, so let the user choose his needs (those that read
out class can handle situations where it could be NULL).

An explicit check for tcf_unbind_filter() is also not needed here, as
the previous r->class was 0, so the xchg() will return that and
therefore a callback to the qdisc's unbind_tcf() is skipped.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 9 deletions

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 7d9241545188..d6c0a0b44afb 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -307,14 +307,11 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
 {
         bool is_bpf, is_ebpf, have_exts = false;
         struct tcf_exts exts;
-        u32 classid;
         int ret;
 
         is_bpf = tb[TCA_BPF_OPS_LEN] && tb[TCA_BPF_OPS];
         is_ebpf = tb[TCA_BPF_FD];
-
-        if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf) ||
-            !tb[TCA_BPF_CLASSID])
+        if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf))
                 return -EINVAL;
 
         tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE);
@@ -322,7 +319,6 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
         if (ret < 0)
                 return ret;
 
-        classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
         if (tb[TCA_BPF_FLAGS]) {
                 u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]);
 
@@ -334,7 +330,6 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
                 have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT;
         }
 
-        prog->res.classid = classid;
         prog->exts_integrated = have_exts;
 
         ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) :
@@ -344,9 +339,12 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
                 return ret;
         }
 
-        tcf_bind_filter(tp, &prog->res, base);
-        tcf_exts_change(tp, &prog->exts, &exts);
+        if (tb[TCA_BPF_CLASSID]) {
+                prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
+                tcf_bind_filter(tp, &prog->res, base);
+        }
 
+        tcf_exts_change(tp, &prog->exts, &exts);
         return 0;
 }
 
@@ -479,7 +477,8 @@ static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
         if (nest == NULL)
                 goto nla_put_failure;
 
-        if (nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid))
+        if (prog->res.classid &&
+            nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid))
                 goto nla_put_failure;
 
         if (cls_bpf_is_ebpf(prog))