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Message-Id: <20221028164948.385783-3-roberto.sassu@huaweicloud.com>
Date: Fri, 28 Oct 2022 18:49:48 +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,
revest@...omium.org, jackmanb@...omium.org, shuah@...nel.org,
paul@...l-moore.com, casey@...aufler-ca.com
Cc: bpf@...r.kernel.org, linux-security-module@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC][PATCH 3/3] selftests/bpf: Check if return values of LSM programs are allowed
From: Roberto Sassu <roberto.sassu@...wei.com>
Ensure that the eBPF verifier allows to load only LSM programs that return
an allowed value depending on the LSM hook they attach to.
Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
---
.../testing/selftests/bpf/verifier/lsm_ret.c | 148 ++++++++++++++++++
1 file changed, 148 insertions(+)
create mode 100644 tools/testing/selftests/bpf/verifier/lsm_ret.c
diff --git a/tools/testing/selftests/bpf/verifier/lsm_ret.c b/tools/testing/selftests/bpf/verifier/lsm_ret.c
new file mode 100644
index 000000000000..1a11f47fb24a
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/lsm_ret.c
@@ -0,0 +1,148 @@
+{
+ "lsm return value: positive not allowed, return -EPERM",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, -EPERM),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "inode_permission",
+ .expected_attach_type = BPF_LSM_MAC,
+ .result = ACCEPT,
+},
+{
+ "lsm return value: positive not allowed, return zero",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "inode_permission",
+ .expected_attach_type = BPF_LSM_MAC,
+ .result = ACCEPT,
+},
+{
+ "lsm return value: positive not allowed, return one",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "inode_permission",
+ .expected_attach_type = BPF_LSM_MAC,
+ .errstr = "Invalid R0, cannot return positive value",
+ .result = REJECT,
+},
+{
+ "lsm return value: zero/positive not allowed, return -EPERM",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, -EPERM),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "inode_init_security",
+ .expected_attach_type = BPF_LSM_MAC,
+ .result = ACCEPT,
+},
+{
+ "lsm return value: zero/positive not allowed, return zero",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "inode_init_security",
+ .expected_attach_type = BPF_LSM_MAC,
+ .errstr = "Invalid R0, cannot return zero value",
+ .result = REJECT,
+},
+{
+ "lsm return value: zero/positive not allowed, return one",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "inode_init_security",
+ .expected_attach_type = BPF_LSM_MAC,
+ .errstr = "Invalid R0, cannot return positive value",
+ .result = REJECT,
+},
+{
+ "lsm return value: positive allowed, return one",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "getprocattr",
+ .expected_attach_type = BPF_LSM_MAC,
+ .result = ACCEPT,
+},
+{
+ "lsm return value: positive allowed, return two",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 2),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "getprocattr",
+ .expected_attach_type = BPF_LSM_MAC,
+ .result = ACCEPT,
+},
+{
+ "lsm return value: only one allowed, return one",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "audit_rule_match",
+ .expected_attach_type = BPF_LSM_MAC,
+ .result = ACCEPT,
+},
+{
+ "lsm return value: only one allowed, return two",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 2),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "audit_rule_match",
+ .expected_attach_type = BPF_LSM_MAC,
+ .errstr = "Invalid R0, can return only one as positive value",
+ .result = REJECT,
+},
+{
+ "lsm return value: negative not allowed, return -EPERM",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, -EPERM),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "vm_enough_memory",
+ .expected_attach_type = BPF_LSM_MAC,
+ .errstr = "Invalid R0, cannot return negative value",
+ .result = REJECT,
+},
+{
+ "lsm return value: negative not allowed, return zero",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "vm_enough_memory",
+ .expected_attach_type = BPF_LSM_MAC,
+ .result = ACCEPT,
+},
+{
+ "lsm return value: negative not allowed, return one",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_LSM,
+ .kfunc = "vm_enough_memory",
+ .expected_attach_type = BPF_LSM_MAC,
+ .result = ACCEPT,
+},
--
2.25.1
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