[PATCH v3] lsm,nscommon: initialize the security blob for the initial namespaces

[sashiko-bot at kernel.org]

> Commit f675d2e95569 ("lsm: add LSM blob and hooks for namespaces")
> added a security blob to struct ns_common and allocates it from
> __ns_common_init(). Most initial namespaces (init_user_ns,
> init_uts_ns, init_pid_ns, init_mnt_ns, and, depending on
> configuration, init_ipc_ns, init_cgroup_ns and init_time_ns) are
> however set up statically via NS_COMMON_INIT() and never pass through
> __ns_common_init(), so their ns_security pointer is left NULL for the
> lifetime of the system. Any LSM that registers an lbs_ns blob and
> dereferences its slice on one of those namespaces (for example from
> the namespace_install hook when a task setns()'s back into an initial
> namespace) will fault.
> 
> Allocate the blob and run the namespace_init hook for each of these
> namespaces at the end of security_init(), after all ordered LSMs have
> registered their hooks, so every LSM sees the initial namespaces the
> same way it sees init_net (which is initialized at runtime via
> ns_common_init(&init_net) from net_ns_init() immediately after
> security_init()) and does not need to special-case them in its own
> ->init() callback.
> 
> Provide a ns_common_init_security() helper in kernel/nscommon.c so
> that the list of statically-defined initial namespaces and their
> Kconfig guards live next to the rest of the ns_common
> infrastructure. init_net is intentionally excluded: pre-initializing
> it here would leak once __ns_common_init() clears ns_security and
> re-allocates.
> 
> Fixes: f675d2e95569 ("lsm: add LSM blob and hooks for namespaces")
> Signed-off-by: Stephen Smalley <stephen.smalley.work at gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260918143142.19435-2-stephen.smalley.work@gmail.com?part=1