linux-kernel - [PATCH bpf-next 06/11] bpf: Rename sanitize_stack_spill to nospec

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Message-ID: <20250313174149.1113165-1-luis.gerhorst@fau.de>
Date: Thu, 13 Mar 2025 18:41:44 +0100
From: Luis Gerhorst <luis.gerhorst@....de>
To: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Puranjay Mohan <puranjay@...nel.org>,
	Xu Kuohai <xukuohai@...weicloud.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Hari Bathini <hbathini@...ux.ibm.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Mykola Lysenko <mykolal@...com>,
	Shuah Khan <shuah@...nel.org>,
	Luis Gerhorst <luis.gerhorst@....de>,
	Henriette Herzog <henriette.herzog@....de>,
	Cupertino Miranda <cupertino.miranda@...cle.com>,
	Matan Shachnai <m.shachnai@...il.com>,
	Dimitar Kanaliev <dimitar.kanaliev@...eground.com>,
	Shung-Hsi Yu <shung-hsi.yu@...e.com>,
	Daniel Xu <dxu@...uu.xyz>,
	bpf@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-kselftest@...r.kernel.org,
	George Guo <guodongtai@...inos.cn>,
	WANG Xuerui <git@...0n.name>,
	Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc: Maximilian Ott <ott@...fau.de>,
	Milan Stephan <milan.stephan@....de>
Subject: [PATCH bpf-next 06/11] bpf: Rename sanitize_stack_spill to nospec_result

This is made to clarify that this flag will cause a nospec to be added
after this insn and can therefore be relied upon to reduce speculative
path analysis.

Signed-off-by: Luis Gerhorst <luis.gerhorst@....de>
Cc: Henriette Herzog <henriette.herzog@....de>
Cc: Maximilian Ott <ott@...fau.de>
Cc: Milan Stephan <milan.stephan@....de>
---
 include/linux/bpf_verifier.h | 2 +-
 kernel/bpf/verifier.c        | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index d6cfc4ee6820..da586dd4703e 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -563,7 +563,7 @@ struct bpf_insn_aux_data {
 	u64 map_key_state; /* constant (32 bit) key tracking for maps */
 	int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
 	u32 seen; /* this insn was processed by the verifier at env->pass_cnt */
-	bool sanitize_stack_spill; /* subject to Spectre v4 sanitation */
+	bool nospec_result; /* result is unsafe under speculation, nospec must follow */
 	bool zext_dst; /* this insn zero extends dst reg */
 	bool needs_zext; /* alu op needs to clear upper bits */
 	bool storage_get_func_atomic; /* bpf_*_storage_get() with atomic memory alloc */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index eb65038682b0..4c1ed31d86af 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5007,7 +5007,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
 		}
 
 		if (sanitize)
-			env->insn_aux_data[insn_idx].sanitize_stack_spill = true;
+			env->insn_aux_data[insn_idx].nospec_result = true;
 	}
 
 	err = destroy_if_dynptr_stack_slot(env, state, spi);
@@ -20719,7 +20719,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 		}
 
 		if (type == BPF_WRITE &&
-		    env->insn_aux_data[i + delta].sanitize_stack_spill) {
+		    env->insn_aux_data[i + delta].nospec_result) {
 			struct bpf_insn patch[] = {
 				*insn,
 				BPF_ST_NOSPEC(),
-- 
2.48.1