On 25-Mär 12:28, Kees Cook wrote: > On Wed, Mar 25, 2020 at 04:26:24PM +0100, KP Singh wrote: > > From: KP Singh <kpsingh@xxxxxxxxxx> > > > > When CONFIG_BPF_LSM is enabled, nop functions, bpf_lsm_<hook_name>, are > > generated for each LSM hook. These functions are initialized as LSM > > hooks in a subsequent patch. > > > > Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx> > > Reviewed-by: Brendan Jackman <jackmanb@xxxxxxxxxx> > > Reviewed-by: Florent Revest <revest@xxxxxxxxxx> > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > > Acked-by: Yonghong Song <yhs@xxxxxx> > > --- > > include/linux/bpf_lsm.h | 22 ++++++++++++++++++++++ > > kernel/bpf/bpf_lsm.c | 14 ++++++++++++++ > > 2 files changed, 36 insertions(+) > > create mode 100644 include/linux/bpf_lsm.h > > > > diff --git a/include/linux/bpf_lsm.h b/include/linux/bpf_lsm.h > > new file mode 100644 > > index 000000000000..83b96895829f > > --- /dev/null > > +++ b/include/linux/bpf_lsm.h > > @@ -0,0 +1,22 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > + > > +/* > > + * Copyright (C) 2020 Google LLC. > > + */ > > + > > +#ifndef _LINUX_BPF_LSM_H > > +#define _LINUX_BPF_LSM_H > > + > > +#include <linux/bpf.h> > > +#include <linux/lsm_hooks.h> > > + > > +#ifdef CONFIG_BPF_LSM > > + > > +#define LSM_HOOK(RET, DEFAULT, NAME, ...) \ > > + RET bpf_lsm_##NAME(__VA_ARGS__); > > +#include <linux/lsm_hook_defs.h> > > +#undef LSM_HOOK > > + > > +#endif /* CONFIG_BPF_LSM */ > > + > > +#endif /* _LINUX_BPF_LSM_H */ > > diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c > > index 82875039ca90..1210a819ca52 100644 > > --- a/kernel/bpf/bpf_lsm.c > > +++ b/kernel/bpf/bpf_lsm.c > > @@ -7,6 +7,20 @@ > > #include <linux/filter.h> > > #include <linux/bpf.h> > > #include <linux/btf.h> > > +#include <linux/lsm_hooks.h> > > +#include <linux/bpf_lsm.h> > > + > > +/* For every LSM hook that allows attachment of BPF programs, declare a nop > > + * function where a BPF program can be attached. > > + */ > > +#define LSM_HOOK(RET, DEFAULT, NAME, ...) \ > > +noinline __weak RET bpf_lsm_##NAME(__VA_ARGS__) \ > > I don't think the __weak is needed any more here? This was suggested in: https://lore.kernel.org/bpf/20200221022537.wbmhdfkdbfvw2pww@ast-mbp/ "I think I saw cases when gcc ignored 'noinline' when function is defined in the same file and still performed inlining while keeping the function body. To be safe I think __weak is necessary. That will guarantee noinline." It happened to work nicely with the previous approach for the special hooks but the actual reason for adding the __weak was to guarrantee that these functions don't get inlined. > > > +{ \ > > + return DEFAULT; \ > > I'm impressed that LSM_RET_VOID actually works. :) All the credit goes to Andrii :) - KP > > -Kees > > > +} > > + > > +#include <linux/lsm_hook_defs.h> > > +#undef LSM_HOOK > > > > const struct bpf_prog_ops lsm_prog_ops = { > > }; > > -- > > 2.20.1 > > > > -- > Kees Cook
