[PATCH net] hsr: check protocol version in hsr_newlink()

[PATCH net] hsr: check protocol version in hsr_newlink()

[Taehee Yoo]

In the current hsr code, only 0 and 1 protocol versions are valid.
But current hsr code doesn't check the version, which is received by
userspace.

Test commands:
    ip link add dummy0 type dummy
    ip link add dummy1 type dummy
    ip link add hsr0 type hsr slave1 dummy0 slave2 dummy1 version 4

In the test commands, version 4 is invalid.
So, the command should be failed.

After this patch, following error will occur.
"Error: hsr: Only versions 0..1 are supported."

Fixes: ee1c27977284 ("net/hsr: Added support for HSR v1")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
---
 net/hsr/hsr_netlink.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
index 5465a395da04..1decb25f6764 100644
--- a/net/hsr/hsr_netlink.c
+++ b/net/hsr/hsr_netlink.c
@@ -69,10 +69,16 @@ static int hsr_newlink(struct net *src_net, struct net_device *dev,
 	else
 		multicast_spec = nla_get_u8(data[IFLA_HSR_MULTICAST_SPEC]);
 
-	if (!data[IFLA_HSR_VERSION])
+	if (!data[IFLA_HSR_VERSION]) {
 		hsr_version = 0;
-	else
+	} else {
 		hsr_version = nla_get_u8(data[IFLA_HSR_VERSION]);
+		if (hsr_version > 1) {
+			NL_SET_ERR_MSG_MOD(extack,
+					   "Only versions 0..1 are supported");
+			return -EINVAL;
+		}
+	}
 
 	return hsr_dev_finalize(dev, link, multicast_spec, hsr_version, extack);
 }
-- 
2.17.1

Re: [PATCH net] hsr: check protocol version in hsr_newlink()

[David Miller]

From: Taehee Yoo <ap420073@gmail.com>
Date: Tue,  7 Apr 2020 13:23:21 +0000

> In the current hsr code, only 0 and 1 protocol versions are valid.
> But current hsr code doesn't check the version, which is received by
> userspace.
> 
> Test commands:
>     ip link add dummy0 type dummy
>     ip link add dummy1 type dummy
>     ip link add hsr0 type hsr slave1 dummy0 slave2 dummy1 version 4
> 
> In the test commands, version 4 is invalid.
> So, the command should be failed.
> 
> After this patch, following error will occur.
> "Error: hsr: Only versions 0..1 are supported."
> 
> Fixes: ee1c27977284 ("net/hsr: Added support for HSR v1")
> Signed-off-by: Taehee Yoo <ap420073@gmail.com>

Applied, thank you.