[PATCHv2 net] net: sched: fix erspan_opt settings in cls_flower

[PATCHv2 net] net: sched: fix erspan_opt settings in cls_flower

[Xin Long]

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: 79b1011cb33d ("net: sched: allow flower to match erspan options")
Reported-by: Shuang Li <shuali@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
v1 -> v2:
 - Initialize the hwid by invoking set_hwid() with 0xff instead of 0x3f,
   as suggested by Cong.
---
 net/sched/cls_flower.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index e280c27cb9f9..1008ec8a464c 100644
--- a/net/sched/cls_flower.c
+++ b/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));
-- 
2.43.0

Re: [PATCHv2 net] net: sched: fix erspan_opt settings in cls_flower

[Cong Wang]

On Mon, Dec 02, 2024 at 10:21:38AM -0500, Xin Long wrote:
> 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: 79b1011cb33d ("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>

Looking forward to your selftest. :)

Thanks.

Re: [PATCHv2 net] net: sched: fix erspan_opt settings in cls_flower

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Mon,  2 Dec 2024 10:21:38 -0500 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [PATCHv2,net] net: sched: fix erspan_opt settings in cls_flower
    https://git.kernel.org/netdev/net/c/292207809486

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html