On Tue, Oct 24, 2023 at 4:56 PM Song Liu <song@xxxxxxxxxx> wrote: > > ARG_PTR_TO_CONST_STR is used to specify constant string args for BPF > helpers. The logic that verifies a reg is ARG_PTR_TO_CONST_STR is > implemented in check_func_arg(). > > As we introduce kfuncs with constant string args, it is necessary to > do the same check for kfuncs (in check_kfunc_args). Factor out the logic > for ARG_PTR_TO_CONST_STR to a new check_reg_const_str() so that it can be > reused. > > check_func_arg() ensures check_reg_const_str() is only called with reg of > type PTR_TO_MAP_VALUE. Add a redundent type check in check_reg_const_str() > to avoid misuse in the future. Other than this redundent check, there is > no change in behavior. > > Signed-off-by: Song Liu <song@xxxxxxxxxx> > --- > kernel/bpf/verifier.c | 85 +++++++++++++++++++++++++------------------ > 1 file changed, 49 insertions(+), 36 deletions(-) > LGTM, I don't feel too strongly about that added WARN_ON_ONCE. Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 857d76694517..238a8e08e781 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -8571,6 +8571,54 @@ static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env, > return state->stack[spi].spilled_ptr.dynptr.type; > } > [...]
