On Fri, Feb 21, 2025 at 12:49 PM Stephen Smalley
<stephen.smalley.work@xxxxxxxxx> wrote:
>
> On Fri, Feb 21, 2025 at 10:59 AM Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote:
> >
> > The NFS4 security label code does not support multiple labels, and
> > is intentionally unaware of which LSM is providing them. It is also
> > the case that currently only one LSM that use security contexts is
> > permitted to be active, as enforced by LSM_FLAG_EXCLUSIVE. Any LSM
> > that receives a release_secctx that is not explicitly designated as
> > for another LSM can safely carry out the release process. The NFS4
> > code identifies the lsm_context as LSM_ID_UNDEF, so allowing the
> > called LSM to perform the release is safe. Additional sophistication
> > will be required when context using LSMs are allowed to be used
> > together.
>
> Shrug. This seems less safe to me but I will give it a try with
> SELinux labeled NFS tests.
My kernel with this patch seems to be crashing during the NFS tests
but not 100% sure yet if it is your patch's fault or something else.
>
> >
> > Fixes: b530104f50e8 ("lsm: lsm_context in security_dentry_init_security")
> > Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
> > ---
> > security/apparmor/secid.c | 2 +-
> > security/selinux/hooks.c | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/security/apparmor/secid.c b/security/apparmor/secid.c
> > index 28caf66b9033..db484c214cda 100644
> > --- a/security/apparmor/secid.c
> > +++ b/security/apparmor/secid.c
> > @@ -108,7 +108,7 @@ int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
> >
> > void apparmor_release_secctx(struct lsm_context *cp)
> > {
> > - if (cp->id == LSM_ID_APPARMOR) {
> > + if (cp->id == LSM_ID_APPARMOR || cp->id == LSM_ID_UNDEF) {
> > kfree(cp->context);
> > cp->context = NULL;
> > cp->id = LSM_ID_UNDEF;
> > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > index 7b867dfec88b..b89d3438b3df 100644
> > --- a/security/selinux/hooks.c
> > +++ b/security/selinux/hooks.c
> > @@ -6673,7 +6673,7 @@ static int selinux_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
> >
> > static void selinux_release_secctx(struct lsm_context *cp)
> > {
> > - if (cp->id == LSM_ID_SELINUX) {
> > + if (cp->id == LSM_ID_SELINUX || cp->id == LSM_ID_UNDEF) {
> > kfree(cp->context);
> > cp->context = NULL;
> > cp->id = LSM_ID_UNDEF;
> >
