diff mbox series

[bpf-next,v2,1/4] bpf: verifier: make kfuncs args nullalble

Message ID 20240510122823.1530682-2-vadfed@meta.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf: make trusted args nullable | expand

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Commit Message

Vadim Fedorenko May 10, 2024, 12:28 p.m. UTC 
Some arguments to kfuncs might be NULL in some cases. But currently it's
not possible to pass NULL to any BTF structures because the check for
the suffix is located after all type checks. Move it to earlier place
to allow nullable args.

Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
---
 kernel/bpf/verifier.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Eduard Zingerman May 21, 2024, 7:48 p.m. UTC | #1 
On Fri, 2024-05-10 at 05:28 -0700, Vadim Fedorenko wrote:
> Some arguments to kfuncs might be NULL in some cases. But currently it's
> not possible to pass NULL to any BTF structures because the check for
> the suffix is located after all type checks. Move it to earlier place
> to allow nullable args.
> 
> Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

>  kernel/bpf/verifier.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 9e3aba08984e..ed67aed3c284 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -11179,6 +11179,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
>  	if (btf_is_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno))
>  		return KF_ARG_PTR_TO_CTX;
>  
> +	if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && register_is_null(reg))
> +		return KF_ARG_PTR_TO_NULL;
> +

Nit: maybe move this above the KF_ARG_PTR_TO_CTX check as well?
diff mbox series

Patch

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9e3aba08984e..ed67aed3c284 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11179,6 +11179,9 @@  get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
 	if (btf_is_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno))
 		return KF_ARG_PTR_TO_CTX;
 
+	if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && register_is_null(reg))
+		return KF_ARG_PTR_TO_NULL;
+
 	if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno]))
 		return KF_ARG_PTR_TO_ALLOC_BTF_ID;
 
@@ -11224,9 +11227,6 @@  get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
 	if (is_kfunc_arg_callback(env, meta->btf, &args[argno]))
 		return KF_ARG_PTR_TO_CALLBACK;
 
-	if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && register_is_null(reg))
-		return KF_ARG_PTR_TO_NULL;
-
 	if (argno + 1 < nargs &&
 	    (is_kfunc_arg_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1]) ||
 	     is_kfunc_arg_const_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1])))