netdev - [PATCH net] bpf/verifier: reject BPF_ALU64|BPF

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Message-ID: <8c3d5513-6171-3e68-56df-1efd0e87f071@solarflare.com>
Date:   Fri, 15 Sep 2017 14:37:38 +0100
From:   Edward Cree <ecree@...arflare.com>
To:     David Miller <davem@...emloft.net>
CC:     netdev <netdev@...r.kernel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH net] bpf/verifier: reject BPF_ALU64|BPF_END

Neither ___bpf_prog_run nor the JITs accept it.
Also adds a new test case.

Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)")
Signed-off-by: Edward Cree <ecree@...arflare.com>
---
 kernel/bpf/verifier.c                       |  3 ++-
 tools/testing/selftests/bpf/test_verifier.c | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 477b693..799b245 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2292,7 +2292,8 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
 			}
 		} else {
 			if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
-			    (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
+			    (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
+			    BPF_CLASS(insn->code) == BPF_ALU64) {
 				verbose("BPF_END uses reserved fields\n");
 				return -EINVAL;
 			}
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 8eb0995..26f3250 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -6629,6 +6629,22 @@ static struct bpf_test tests[] = {
 		.result = REJECT,
 		.flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
 	},
+	{
+		"invalid 64-bit BPF_END",
+		.insns = {
+			BPF_MOV32_IMM(BPF_REG_0, 0),
+			{
+				.code  = BPF_ALU64 | BPF_END | BPF_TO_LE,
+				.dst_reg = BPF_REG_0,
+				.src_reg = 0,
+				.off   = 0,
+				.imm   = 32,
+			},
+			BPF_EXIT_INSN(),
+		},
+		.errstr = "BPF_END uses reserved fields",
+		.result = REJECT,
+	},
 };
 
 static int probe_filter_length(const struct bpf_insn *fp)