linux-kernel - [PATCH bpf-next v5 05/11] bpf: Move BPF_STX reserved field check into BPF

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Message-Id: <20201215121816.1048557-7-jackmanb@google.com>
Date:   Tue, 15 Dec 2020 12:18:10 +0000
From:   Brendan Jackman <jackmanb@...gle.com>
To:     bpf@...r.kernel.org
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Florent Revest <revest@...omium.org>,
        linux-kernel@...r.kernel.org,
        Brendan Jackman <jackmanb@...gle.com>,
        Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>
Subject: [PATCH bpf-next v5 05/11] bpf: Move BPF_STX reserved field check into
 BPF_STX verifier code

I can't find a reason why this code is in resolve_pseudo_ldimm64;
since I'll be modifying it in a subsequent commit, tidy it up.

Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
Acked-by: Yonghong Song <yhs@...com>
Acked-by: John Fastabend <john.fastabend@...il.com>
---
 kernel/bpf/verifier.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d562268c1fd1..48e398667a69 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9528,6 +9528,12 @@ static int do_check(struct bpf_verifier_env *env)
 		} else if (class == BPF_STX) {
 			enum bpf_reg_type *prev_dst_type, dst_reg_type;
 
+			if (((BPF_MODE(insn->code) != BPF_MEM &&
+			      BPF_MODE(insn->code) != BPF_ATOMIC) || insn->imm != 0)) {
+				verbose(env, "BPF_STX uses reserved fields\n");
+				return -EINVAL;
+			}
+
 			if (BPF_MODE(insn->code) == BPF_ATOMIC) {
 				err = check_atomic(env, env->insn_idx, insn);
 				if (err)
@@ -9940,13 +9946,6 @@ static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env)
 			return -EINVAL;
 		}
 
-		if (BPF_CLASS(insn->code) == BPF_STX &&
-		    ((BPF_MODE(insn->code) != BPF_MEM &&
-		      BPF_MODE(insn->code) != BPF_ATOMIC) || insn->imm != 0)) {
-			verbose(env, "BPF_STX uses reserved fields\n");
-			return -EINVAL;
-		}
-
 		if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
 			struct bpf_insn_aux_data *aux;
 			struct bpf_map *map;
-- 
2.29.2.684.gfbc64c5ab5-goog