On Sep 27, 2023 Andrii Nakryiko <andrii@xxxxxxxxxx> wrote:
>
> Add basic support of BPF token to BPF_PROG_LOAD. Wire through a set of
> allowed BPF program types and attach types, derived from BPF FS at BPF
> token creation time. Then make sure we perform bpf_token_capable()
> checks everywhere where it's relevant.
>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> ---
> include/linux/bpf.h | 6 ++
> include/uapi/linux/bpf.h | 2 +
> kernel/bpf/core.c | 1 +
> kernel/bpf/inode.c | 6 +-
> kernel/bpf/syscall.c | 87 ++++++++++++++-----
> kernel/bpf/token.c | 25 ++++++
> tools/include/uapi/linux/bpf.h | 2 +
> .../selftests/bpf/prog_tests/libbpf_probes.c | 2 +
> .../selftests/bpf/prog_tests/libbpf_str.c | 3 +
> 9 files changed, 108 insertions(+), 26 deletions(-)
...
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 5c5c2b6648b2..d0b219f09bcc 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2685,6 +2718,10 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
> prog->aux->sleepable = attr->prog_flags & BPF_F_SLEEPABLE;
> prog->aux->xdp_has_frags = attr->prog_flags & BPF_F_XDP_HAS_FRAGS;
>
> + /* move token into prog->aux, reuse taken refcnt */
> + prog->aux->token = token;
> + token = NULL;
> +
> err = security_bpf_prog_alloc(prog->aux);
> if (err)
> goto free_prog;
As we discussed in the earlier thread, let's tweak/rename/move the
security_bpf_prog_alloc() call down to just before the bpf_check() call
so it looks something like this:
err = security_bpf_prog_load(prog, &attr, token);
if (err)
goto proper_jump_label;
err = bpf_check(...);
With the idea being that LSMs which implement the token hooks would
skip any BPF_PROG_LOAD access controls in security_bpf() and instead
implement them in security_bpf_prog_load().
We should also do something similar for map_create() and
security_bpf_map_alloc() in patch 4/13.
--
paul-moore.com
