net: sched: fix erspan_opt settings in cls_flower

JIRA: https://issues.redhat.com/browse/RHEL-73195
Tested: compile only

commit 2922078
Author: Xin Long <lucien.xin@gmail.com>
Date:   Mon Dec 2 10:21:38 2024 -0500

    net: sched: fix erspan_opt settings in cls_flower

    When matching erspan_opt in cls_flower, only the (version, dir, hwid)
    fields are relevant. However, in fl_set_erspan_opt() it initializes
    all bits of erspan_opt and its mask to 1. This inadvertently requires
    packets to match not only the (version, dir, hwid) fields but also the
    other fields that are unexpectedly set to 1.

    This patch resolves the issue by ensuring that only the (version, dir,
    hwid) fields are configured in fl_set_erspan_opt(), leaving the other
    fields to 0 in erspan_opt.

    Fixes: 79b1011 ("net: sched: allow flower to match erspan options")
    Reported-by: Shuang Li <shuali@redhat.com>
    Signed-off-by: Xin Long <lucien.xin@gmail.com>
    Reviewed-by: Cong Wang <cong.wang@bytedance.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Xin Long <lxin@redhat.com>

Author: Xin Long

net/sched/cls_flower.c

@@ -1369,7 +1369,6 @@ static int fl_set_erspan_opt(const struct nlattr *nla, struct fl_flow_key *key,
 	int err;
 
 	md = (struct erspan_metadata *)&key->enc_opts.data[key->enc_opts.len];
-	memset(md, 0xff, sizeof(*md));
 	md->version = 1;
 
 	if (!depth)
@@ -1398,9 +1397,9 @@ static int fl_set_erspan_opt(const struct nlattr *nla, struct fl_flow_key *key,
 			NL_SET_ERR_MSG(extack, "Missing tunnel key erspan option index");
 			return -EINVAL;
 		}
+		memset(&md->u.index, 0xff, sizeof(md->u.index));
 		if (tb[TCA_FLOWER_KEY_ENC_OPT_ERSPAN_INDEX]) {
 			nla = tb[TCA_FLOWER_KEY_ENC_OPT_ERSPAN_INDEX];
-			memset(&md->u, 0x00, sizeof(md->u));
 			md->u.index = nla_get_be32(nla);
 		}
 	} else if (md->version == 2) {
@@ -1409,10 +1408,12 @@ static int fl_set_erspan_opt(const struct nlattr *nla, struct fl_flow_key *key,
 			NL_SET_ERR_MSG(extack, "Missing tunnel key erspan option dir or hwid");
 			return -EINVAL;
 		}
+		md->u.md2.dir = 1;
 		if (tb[TCA_FLOWER_KEY_ENC_OPT_ERSPAN_DIR]) {
 			nla = tb[TCA_FLOWER_KEY_ENC_OPT_ERSPAN_DIR];
 			md->u.md2.dir = nla_get_u8(nla);
 		}
+		set_hwid(&md->u.md2, 0xff);
 		if (tb[TCA_FLOWER_KEY_ENC_OPT_ERSPAN_HWID]) {
 			nla = tb[TCA_FLOWER_KEY_ENC_OPT_ERSPAN_HWID];
 			set_hwid(&md->u.md2, nla_get_u8(nla));