Re: [RFC PATCH v1 02/11] security: Add LSM_AUDIT_DATA_NS for namespace audit records

Günther Noack
2026-04-22T21:21:38Z

On Thu, Mar 12, 2026 at 11:04:35AM +0100, Mickaël Salaün wrote:
> Add a new LSM audit data type LSM_AUDIT_DATA_NS that logs namespace
> information in audit records. Two fields are provided, matching the
> field names of struct ns_common:
>
> - ns_type: the CLONE_NEW* flag identifying the namespace type, logged in
> hexadecimal.
>
> - inum: the proc inode number identifying a specific namespace instance.
> Namespace inode numbers are allocated by proc_alloc_inum() via
> ida_alloc_max() bounded to UINT_MAX, so the value always fits in 32
> bits.
>
> A new audit data type is needed because no existing LSM_AUDIT_DATA_*
> type carries namespace information. The closest alternatives (e.g.
> LSM_AUDIT_DATA_TASK or LSM_AUDIT_DATA_NONE with custom strings) would
> either lose the namespace type or require ad-hoc formatting that
> bypasses the structured audit data union.
>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Günther Noack <gnoack@google.com>
> Cc: Paul Moore <paul@paul-moore.com>
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> ---
> include/linux/lsm_audit.h | 5 +++++
> security/lsm_audit.c | 4 ++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
> index 382c56a97bba..6e20a56b8c22 100644
> --- a/include/linux/lsm_audit.h
> +++ b/include/linux/lsm_audit.h
> @@ -78,6 +78,7 @@ struct common_audit_data {
> #define LSM_AUDIT_DATA_NOTIFICATION 16
> #define LSM_AUDIT_DATA_ANONINODE 17
> #define LSM_AUDIT_DATA_NLMSGTYPE 18
> +#define LSM_AUDIT_DATA_NS 19
> union {
> struct path path;
> struct dentry *dentry;
> @@ -100,6 +101,10 @@ struct common_audit_data {
> int reason;
> const char *anonclass;
> u16 nlmsg_type;
> + struct {
> + u32 ns_type;
> + unsigned int inum;
> + } ns;
> } u;
> /* this union contains LSM specific data */
> union {
> diff --git a/security/lsm_audit.c b/security/lsm_audit.c
> index 7d623b00495c..7f71a77c1c12 100644
> --- a/security/lsm_audit.c
> +++ b/security/lsm_audit.c
> @@ -403,6 +403,10 @@ void audit_log_lsm_data(struct audit_buffer *ab,
> case LSM_AUDIT_DATA_NLMSGTYPE:
> audit_log_format(ab, " nl-msgtype=%hu", a->u.nlmsg_type);
> break;
> + case LSM_AUDIT_DATA_NS:
> + audit_log_format(ab, " namespace_type=0x%x namespace_inum=%u",
> + a->u.ns.ns_type, a->u.ns.inum);
> + break;
> } /* switch (a->type) */
> }
>
> --
> 2.53.0
>

Reviewed-by: Günther Noack <gnoack3000@gmail.com>