linux-kernel - [PATCH v14 12/12] selftests/bpf: Add verifier tests for dynamic pointers parameters in kfuncs

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Date:   Tue, 30 Aug 2022 18:17:16 +0200
From:   Roberto Sassu <roberto.sassu@...weicloud.com>
To:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        martin.lau@...ux.dev, song@...nel.org, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
        haoluo@...gle.com, jolsa@...nel.org, mykolal@...com,
        dhowells@...hat.com, jarkko@...nel.org, rostedt@...dmis.org,
        mingo@...hat.com, paul@...l-moore.com, jmorris@...ei.org,
        serge@...lyn.com, shuah@...nel.org
Cc:     bpf@...r.kernel.org, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        deso@...teo.net, memxor@...il.com,
        Roberto Sassu <roberto.sassu@...wei.com>
Subject: [PATCH v14 12/12] selftests/bpf: Add verifier tests for dynamic pointers parameters in kfuncs

From: Roberto Sassu <roberto.sassu@...wei.com>

Add verifier tests to ensure that only supported dynamic pointer types are
accepted, that the passed argument is actually a dynamic pointer, and that
the passed argument is a pointer to the stack.

Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
---
 .../bpf/verifier/kfunc_dynptr_param.c         | 72 +++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/verifier/kfunc_dynptr_param.c

diff --git a/tools/testing/selftests/bpf/verifier/kfunc_dynptr_param.c b/tools/testing/selftests/bpf/verifier/kfunc_dynptr_param.c
new file mode 100644
index 000000000000..8abb8d566321
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/kfunc_dynptr_param.c
@@ -0,0 +1,72 @@
+{
+	"kfunc dynamic pointer param: type not supported",
+	.insns = {
+	BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0),
+	BPF_MOV64_REG(BPF_REG_6, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -16),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_MOV64_IMM(BPF_REG_2, 8),
+	BPF_MOV64_IMM(BPF_REG_3, 0),
+	BPF_MOV64_REG(BPF_REG_4, BPF_REG_6),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve_dynptr),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_6),
+	BPF_MOV64_IMM(BPF_REG_3, 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_MOV64_IMM(BPF_REG_2, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_discard_dynptr),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_ringbuf = { 3 },
+	.prog_type = BPF_PROG_TYPE_LSM,
+	.kfunc = "bpf",
+	.expected_attach_type = BPF_LSM_MAC,
+	.flags = BPF_F_SLEEPABLE,
+	.errstr = "arg#0 pointer type STRUCT bpf_dynptr_kern points to unsupported dynamic pointer type",
+	.result = REJECT,
+	.fixup_kfunc_btf_id = {
+		{ "bpf_verify_pkcs7_signature", 12 },
+	},
+},
+{
+	"kfunc dynamic pointer param: arg not a dynamic pointer",
+	.insns = {
+	BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8),
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_1),
+	BPF_MOV64_IMM(BPF_REG_3, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_LSM,
+	.kfunc = "bpf",
+	.expected_attach_type = BPF_LSM_MAC,
+	.flags = BPF_F_SLEEPABLE,
+	.errstr = "arg#0 pointer type STRUCT bpf_dynptr_kern must be valid and initialized",
+	.result = REJECT,
+	.fixup_kfunc_btf_id = {
+		{ "bpf_verify_pkcs7_signature", 5 },
+	},
+},
+{
+	"kfunc dynamic pointer param: arg not a pointer to stack",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, 0),
+	BPF_MOV64_IMM(BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_3, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_LSM,
+	.kfunc = "bpf",
+	.expected_attach_type = BPF_LSM_MAC,
+	.flags = BPF_F_SLEEPABLE,
+	.errstr = "arg#0 pointer type STRUCT bpf_dynptr_kern not to stack",
+	.result = REJECT,
+	.fixup_kfunc_btf_id = {
+		{ "bpf_verify_pkcs7_signature", 3 },
+	},
+},
-- 
2.25.1