On 09/02/2026 17:44, Ilya Maximets wrote:
External email: Use caution opening links or attachments
On 2/9/26 4:19 PM, Eli Britstein wrote:
A linux interface is limited to IFNAMSIZ length (16). In case a tap
interface is created, add a validity check for it.
Hi, Eli.
OpenFlow and Linux have the same limit for the port name.
How is it possible to create a port that is larger?
ovs-vsctl add-br a234567890b234567890 -- set br a234567890b234567890
datapath_type=netdev
Signed-off-by: Eli Britstein <[email protected]>
---
lib/netdev-linux.c | 7 +++++++
tests/ovs-ofctl.at | 21 +--------------------
2 files changed, 8 insertions(+), 20 deletions(-)
diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index f4d2685a2..32222b683 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -962,6 +962,13 @@ netdev_linux_common_construct(struct netdev *netdev_)
name);
return EINVAL;
}
+ if (strlen(name) >= IFNAMSIZ) {
+ static struct vlog_rate_limit rll = VLOG_RATE_LIMIT_INIT(1, 1);
+
+ VLOG_WARN_RL(&rll, "%s: Linux forbids network device with this name "
+ "(too long)", name);
+ return ENAMETOOLONG;
+ }
/* The device could be in the same network namespace or in another one. */
netnsid_unset(&netdev->netnsid);
diff --git a/tests/ovs-ofctl.at b/tests/ovs-ofctl.at
index 751a934e4..871bdcc19 100644
--- a/tests/ovs-ofctl.at
+++ b/tests/ovs-ofctl.at
@@ -3105,33 +3105,14 @@ AT_KEYWORDS([port names])
OVS_VSWITCHD_START([\
-- add-port br0 xyzzy -- set Interface xyzzy type=dummy -- \
-- add-port br0 x-y -- set Interface x-y type=dummy -- \
- -- add-port br0 abc123 -- set Interface abc123 type=dummy -- \
- -- add-port br0 reallyverylongportname -- set Interface
reallyverylongportname type=dummy -- \
- -- add-port br0 conflictinglongportname1 -- set Interface
conflictinglongportname1 type=dummy -- \
- -- add-port br0 conflictinglongportname2 -- set Interface
conflictinglongportname2 type=dummy])
+ -- add-port br0 abc123 -- set Interface abc123 type=dummy])
# These plain port names should be accepted.
AT_CHECK([ovs-ofctl add-flow br0 in_port=xyzzy,actions=x-y,abc123])
-# reallyverylongportname is accepted truncated, but not in full.
-AT_CHECK([ovs-ofctl add-flow br0 in_port=reallyverylongp,actions=drop])
-AT_CHECK([ovs-ofctl add-flow br0 in_port=reallyverylongportname,actions=drop],
- [1], [], [ovs-ofctl: reallyverylongportname: invalid or unknown port for
in_port
-])
-
-# conflictinglongportname1 and 2 can't be accepted even truncated, since
-# they conflict when truncated.
-AT_CHECK([ovs-ofctl add-flow br0
in_port=conflictinglongportname1,actions=drop], [1], [], [ovs-ofctl:
conflictinglongportname1: invalid or unknown port for in_port
-])
-AT_CHECK([ovs-ofctl add-flow br0
in_port=conflictinglongportname2,actions=drop], [1], [], [ovs-ofctl:
conflictinglongportname2: invalid or unknown port for in_port
-])
-AT_CHECK([ovs-ofctl add-flow br0 in_port=conflictinglong,actions=drop], [1],
[], [ovs-ofctl: conflictinglong: invalid or unknown port for in_port
-])
-
# Show that the port names get displayed properly and that port names that
# aren't alphanumeric get quoted.
AT_CHECK([ovs-ofctl --names dump-flows br0 | ofctl_strip | sort], [0], [dnl
- in_port=reallyverylongp actions=drop
in_port=xyzzy actions=output:"x-y",output:abc123
])
OVS_VSWITCHD_STOP
This test seems completely valid to me. It should stay as is.
Since I add this validity check, deliberately creating too long names
for checking truncating seems wrong to me, as they would fail if not dummy.
Best regards, Ilya Maximets.
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