On Fri, Oct 13, 2023 at 2:15 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote:
>
> On Oct 12, 2023 Andrii Nakryiko <andrii@xxxxxxxxxx> wrote:
> >
> > Wire up bpf_token_create and bpf_token_free LSM hooks, which allow to
> > allocate LSM security blob (we add `void *security` field to struct
> > bpf_token for that), but also control who can instantiate BPF token.
> > This follows existing pattern for BPF map and BPF prog.
> >
> > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> > ---
> > include/linux/bpf.h | 3 +++
> > include/linux/lsm_hook_defs.h | 3 +++
> > include/linux/security.h | 11 +++++++++++
> > kernel/bpf/bpf_lsm.c | 2 ++
> > kernel/bpf/token.c | 6 ++++++
> > security/security.c | 28 ++++++++++++++++++++++++++++
> > 6 files changed, 53 insertions(+)
>
> ...
>
> > diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c
> > index d4e0cc8075d3..18fd1e04f92d 100644
> > --- a/kernel/bpf/token.c
> > +++ b/kernel/bpf/token.c
> > @@ -7,6 +7,7 @@
> > #include <linux/idr.h>
> > #include <linux/namei.h>
> > #include <linux/user_namespace.h>
> > +#include <linux/security.h>
> >
> > bool bpf_token_capable(const struct bpf_token *token, int cap)
> > {
> > @@ -28,6 +29,7 @@ void bpf_token_inc(struct bpf_token *token)
> >
> > static void bpf_token_free(struct bpf_token *token)
> > {
> > + security_bpf_token_free(token);
> > put_user_ns(token->userns);
> > kvfree(token);
> > }
> > @@ -183,6 +185,10 @@ int bpf_token_create(union bpf_attr *attr)
> > token->allowed_progs = mnt_opts->delegate_progs;
> > token->allowed_attachs = mnt_opts->delegate_attachs;
> >
> > + err = security_bpf_token_create(token, attr, &path);
> > + if (err)
> > + goto out_token;
> > +
> > fd = get_unused_fd_flags(O_CLOEXEC);
> > if (fd < 0) {
> > err = fd;
>
> As long as bpf_token_alloc() remains separate from bpf_token_create()
> I'm not comfortable not having a security_bpf_token_alloc() hook in
> bpf_token_alloc(). If you really don't want a LSM token alloc hook
> can you fold bpf_token_alloc() into bpf_token_create()?
Yeah, that's easy, I'll just inline it into bpf_token_create(), which
is the only place where I was intending to use it anyways. I just want
to keep all this consistent between map, token, and progs.
>
> --
> paul-moore.com
