In the Linux kernel, the following vulnerability has been resolved:
net: sit: require CAP_NET_ADMIN in the device netns for changelink
ipip6_changelink() operates on at most two netns, dev_net(dev) and the tunnel link netns t->net. They differ once the device is created in or moved to a netns other than the one the request runs in. The rtnl changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a caller privileged there but not in t->net can rewrite a tunnel that lives in t->net.
Gate ipip6_changelink() on rtnl_dev_link_net_capable() at its top, before any attribute is parsed. sit was the one tunnel type not covered by the recent series that added this check to the other changelink() handlers.
References
- https://git.kernel.org/stable/c/27ccb68e7cccead5d8c611665a45d23032d468b3
- https://git.kernel.org/stable/c/3118e97dae533fb45964b87bbed1801afcff7c65
- https://git.kernel.org/stable/c/388ccffbd2e7e5e4271f291085a7451865705305
- https://git.kernel.org/stable/c/7d139dec96691cde96cb40ed293e2d13d994fb4f
- https://git.kernel.org/stable/c/99ae3248b33df94201915d9c32e7470cdf08cfcd
- https://git.kernel.org/stable/c/c0ea1aedb37bb979e864ed7787975434bbd9db73
- https://git.kernel.org/stable/c/c5a0ae895432596b2f464172da8218e2d84e2932
- https://git.kernel.org/stable/c/cb41b308e9d867725d965b291dd085028e36a480