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rtnetlink: Allow deleting FDB entries in user namespace

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Creating FDB entries is possible from a non-initial user namespace when
having CAP_NET_ADMIN, yet, when deleting FDB entries, processes receive
an EPERM because the capability is always checked against the initial
user namespace. This restricts the FDB management from unprivileged
containers.

Drop the netlink_capable check in rtnl_fdb_del as it was originally
dropped in c5c351088a and reintroduced in 1690be63a2 without
intention.

This patch was tested using a container on GyroidOS, where it was
possible to delete FDB entries from an unprivileged user namespace and
private network namespace.

Fixes: 1690be63a2 ("bridge: Add vlan support to static neighbors")
Reviewed-by: Michael Weiß <michael.weiss@aisec.fraunhofer.de>
Tested-by: Harshal Gohel <hg@simonwunderlich.de>
Signed-off-by: Johannes Wiesböck <johannes.wiesboeck@aisec.fraunhofer.de>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20251015201548.319871-1-johannes.wiesboeck@aisec.fraunhofer.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Johannes Wiesböck
2025-10-15 22:15:43 +02:00
committed by Jakub Kicinski
parent 1b0124ad50
commit bf29555f5b
1 changed files with 0 additions and 3 deletions
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3
net/core/rtnetlink.c
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@@ -4715,9 +4715,6 @@ static int rtnl_fdb_del(struct sk_buff *skb, struct nlmsghdr *nlh,
int err;
u16 vid;
if (!netlink_capable(skb, CAP_NET_ADMIN))
return -EPERM;
if (!del_bulk) {
err = nlmsg_parse_deprecated(nlh, sizeof(*ndm), tb, NDA_MAX,
NULL, extack);