[PATCH 5/8] ns: allocate the namespace id before the namespace_init hook

[sashiko-bot at kernel.org]

> Currently the namespace id is allocated only after __ns_common_init()
> has called the namespace_init LSM hook. Most namespace types allocate it
> in ns_tree_add() right before the namespace is added to the namespace
> trees. So the namespace_init hook always sees an id of zero.
> 
> The namespace id is the only identifier of a namespace that is never
> recycled. A bpf LSM wants to use it to track a namespace from
> namespace_init until namespace_free, e.g., by using it as the key into a
> map that associates data with the namespace. The inode number doesn't
> work for that as it is quickly recycled.
> 
> So allocate the id in __ns_common_init() before calling the
> namespace_init hook. Every namespace then has its id by the time it is
> added to the namespace trees. The initial namespaces still get their
> fixed ids, either statically from NS_COMMON_INIT() or for init_net from
> [ ... ]
>   after:  @[set]: 200
> 
> Fixes: f675d2e95569 ("lsm: add LSM blob and hooks for namespaces")
> Cc: <stable at kernel.org> # mainline only
> Signed-off-by: Christian Brauner (Amutable) <brauner at kernel.org>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261026-work-security-namespace_free-v1-0-ffa3ebbf71bd@kernel.org?part=5