selftests/bpf: Add verifier tests for bpf_lookup_*_key() and bpf_key_put()

Add verifier tests for bpf_lookup_*_key() and bpf_key_put(), to ensure that
acquired key references stored in the bpf_key structure are released, that
a non-NULL bpf_key pointer is passed to bpf_key_put(), and that key
references are not leaked.

Also, slightly modify test_verifier.c, to find the BTF ID of the attach
point for the LSM program type (currently, it is done only for TRACING).
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220920075951.929132-11-roberto.sassu@huaweicloud.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/config

@@ -30,6 +30,7 @@ CONFIG_IPV6_GRE=y
 CONFIG_IPV6_SEG6_BPF=y
 CONFIG_IPV6_SIT=y
 CONFIG_IPV6_TUNNEL=y
+CONFIG_KEYS=y
 CONFIG_LIRC=y
 CONFIG_LWTUNNEL=y
 CONFIG_MPLS=y

tools/testing/selftests/bpf/test_verifier.c

@@ -1498,7 +1498,8 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 		opts.log_level = DEFAULT_LIBBPF_LOG_LEVEL;
 	opts.prog_flags = pflags;
 
-	if (prog_type == BPF_PROG_TYPE_TRACING && test->kfunc) {
+	if ((prog_type == BPF_PROG_TYPE_TRACING ||
+	     prog_type == BPF_PROG_TYPE_LSM) && test->kfunc) {
 		int attach_btf_id;
 
 		attach_btf_id = libbpf_find_vmlinux_btf_id(test->kfunc,

tools/testing/selftests/bpf/verifier/ref_tracking.c

@@ -84,6 +84,145 @@
 	.errstr = "Unreleased reference",
 	.result = REJECT,
 },
+{
+	"reference tracking: acquire/release user key reference",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, -3),
+	BPF_MOV64_IMM(BPF_REG_2, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+	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_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_LSM,
+	.kfunc = "bpf",
+	.expected_attach_type = BPF_LSM_MAC,
+	.flags = BPF_F_SLEEPABLE,
+	.fixup_kfunc_btf_id = {
+		{ "bpf_lookup_user_key", 2 },
+		{ "bpf_key_put", 5 },
+	},
+	.result = ACCEPT,
+},
+{
+	"reference tracking: acquire/release system key reference",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, 1),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+	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_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_LSM,
+	.kfunc = "bpf",
+	.expected_attach_type = BPF_LSM_MAC,
+	.flags = BPF_F_SLEEPABLE,
+	.fixup_kfunc_btf_id = {
+		{ "bpf_lookup_system_key", 1 },
+		{ "bpf_key_put", 4 },
+	},
+	.result = ACCEPT,
+},
+{
+	"reference tracking: release user key reference without check",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, -3),
+	BPF_MOV64_IMM(BPF_REG_2, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 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_IMM(BPF_REG_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_key must point to scalar, or struct with scalar",
+	.fixup_kfunc_btf_id = {
+		{ "bpf_lookup_user_key", 2 },
+		{ "bpf_key_put", 4 },
+	},
+	.result = REJECT,
+},
+{
+	"reference tracking: release system key reference without check",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, 1),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 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_IMM(BPF_REG_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_key must point to scalar, or struct with scalar",
+	.fixup_kfunc_btf_id = {
+		{ "bpf_lookup_system_key", 1 },
+		{ "bpf_key_put", 3 },
+	},
+	.result = REJECT,
+},
+{
+	"reference tracking: release with NULL key pointer",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, 0),
+	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_LSM,
+	.kfunc = "bpf",
+	.expected_attach_type = BPF_LSM_MAC,
+	.flags = BPF_F_SLEEPABLE,
+	.errstr = "arg#0 pointer type STRUCT bpf_key must point to scalar, or struct with scalar",
+	.fixup_kfunc_btf_id = {
+		{ "bpf_key_put", 1 },
+	},
+	.result = REJECT,
+},
+{
+	"reference tracking: leak potential reference to user key",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, -3),
+	BPF_MOV64_IMM(BPF_REG_2, 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 = "Unreleased reference",
+	.fixup_kfunc_btf_id = {
+		{ "bpf_lookup_user_key", 2 },
+	},
+	.result = REJECT,
+},
+{
+	"reference tracking: leak potential reference to system key",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_1, 1),
+	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 = "Unreleased reference",
+	.fixup_kfunc_btf_id = {
+		{ "bpf_lookup_system_key", 1 },
+	},
+	.result = REJECT,
+},
 {
 	"reference tracking: release reference without check",
 	.insns = {