netdev - [PATCH v3 bpf-next 2/5] selftests/bpf: Add verifier selftests for forced kfunc ref args

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Message-Id: <987c9577695ef9d03c839100289dc432c7e22e4a.1652870182.git.lorenzo@kernel.org>
Date:   Wed, 18 May 2022 12:43:35 +0200
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, davem@...emloft.net, kuba@...nel.org,
        edumazet@...gle.com, pabeni@...hat.com, pablo@...filter.org,
        fw@...len.de, netfilter-devel@...r.kernel.org,
        lorenzo.bianconi@...hat.com, brouer@...hat.com, toke@...hat.com,
        memxor@...il.com
Subject: [PATCH v3 bpf-next 2/5] selftests/bpf: Add verifier selftests for forced kfunc ref args

From: Kumar Kartikeya Dwivedi <memxor@...il.com>

Make sure verifier rejects the bad cases and ensure the good case keeps
working. The selftests make use of the bpf_kfunc_call_test_ref kfunc
added in the previous patch only for verification.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@...il.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 tools/testing/selftests/bpf/verifier/calls.c | 53 ++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c
index 743ed34c1238..3fb4f69b1962 100644
--- a/tools/testing/selftests/bpf/verifier/calls.c
+++ b/tools/testing/selftests/bpf/verifier/calls.c
@@ -218,6 +218,59 @@
 	.result = REJECT,
 	.errstr = "variable ptr_ access var_off=(0x0; 0x7) disallowed",
 },
+{
+	"calls: invalid kfunc call: referenced arg needs refcounted PTR_TO_BTF_ID",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+	BPF_EXIT_INSN(),
+	BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 16),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.fixup_kfunc_btf_id = {
+		{ "bpf_kfunc_call_test_acquire", 3 },
+		{ "bpf_kfunc_call_test_ref", 8 },
+		{ "bpf_kfunc_call_test_ref", 10 },
+	},
+	.result_unpriv = REJECT,
+	.result = REJECT,
+	.errstr = "R1 must be referenced",
+},
+{
+	"calls: valid kfunc call: referenced arg needs refcounted PTR_TO_BTF_ID",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+	BPF_EXIT_INSN(),
+	BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.fixup_kfunc_btf_id = {
+		{ "bpf_kfunc_call_test_acquire", 3 },
+		{ "bpf_kfunc_call_test_ref", 8 },
+		{ "bpf_kfunc_call_test_release", 10 },
+	},
+	.result_unpriv = REJECT,
+	.result = ACCEPT,
+},
 {
 	"calls: basic sanity",
 	.insns = {
-- 
2.35.3