[PATCH bpf-next v5 3/3] selftests/bpf: Add tests for bpf_set_retval validation

[Xu Kuohai]

From: Xu Kuohai <xukuohai@xxxxxxxxxx>

Add verifier tests to validate bpf_set_retval argument for cgroup
program types.

Reviewed-by: Emil Tsalapatis <emil@xxxxxxxxxxxxxxx> #v1
Signed-off-by: Xu Kuohai <xukuohai@xxxxxxxxxx>
---
 .../selftests/bpf/prog_tests/verifier.c       |   2 +
 .../selftests/bpf/progs/verifier_set_retval.c | 107 ++++++++++++++++++
 2 files changed, 109 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/verifier_set_retval.c

diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index 219ff2969868..89779d897aba 100644
--- a/tools/testing/selftests/bpf/prog_tests/verifier.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -117,6 +117,7 @@
 #include "verifier_xdp.skel.h"
 #include "verifier_xdp_direct_packet_access.skel.h"
 #include "verifier_bits_iter.skel.h"
+#include "verifier_set_retval.skel.h"
 #include "verifier_lsm.skel.h"
 #include "verifier_jit_inline.skel.h"
 #include "irq.skel.h"
@@ -266,6 +267,7 @@ void test_verifier_xadd(void)                 { RUN(verifier_xadd); }
 void test_verifier_xdp(void)                  { RUN(verifier_xdp); }
 void test_verifier_xdp_direct_packet_access(void) { RUN(verifier_xdp_direct_packet_access); }
 void test_verifier_bits_iter(void) { RUN(verifier_bits_iter); }
+void test_verifier_set_retval(void)            { RUN(verifier_set_retval); }
 void test_verifier_lsm(void)                  { RUN(verifier_lsm); }
 void test_irq(void)			      { RUN(irq); }
 void test_verifier_mtu(void)		      { RUN(verifier_mtu); }
diff --git a/tools/testing/selftests/bpf/progs/verifier_set_retval.c b/tools/testing/selftests/bpf/progs/verifier_set_retval.c
new file mode 100644
index 000000000000..1415cd15cede
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/verifier_set_retval.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+
+SEC("lsm_cgroup/socket_create")
+__description("lsm_cgroup bpf_set_retval success")
+__success
+int BPF_PROG(lsm_cgroup_set_retval_zero_valid, int family, int type, int protocol, int kern)
+{
+	bpf_set_retval(0);
+	return 0;
+}
+
+SEC("lsm_cgroup/socket_create")
+__description("lsm_cgroup bpf_set_retval valid errno")
+__success
+int BPF_PROG(lsm_cgroup_set_retval_negative_valid, int family, int type, int protocol, int kern)
+{
+	bpf_set_retval(-12);
+	return 0;
+}
+
+SEC("lsm_cgroup/socket_create")
+__description("lsm_cgroup bpf_set_retval invalid negative value")
+__failure __msg("should have been in [-4095, 0]")
+int BPF_PROG(lsm_cgroup_set_retval_negative_invalid, int family, int type, int protocol, int kern)
+{
+	bpf_set_retval(-4096);
+	return 0;
+}
+
+SEC("lsm_cgroup/socket_create")
+__description("lsm_cgroup bpf_set_retval invalid positive value")
+__failure __msg("should have been in [-4095, 0]")
+int BPF_PROG(lsm_cgroup_set_retval_positive_invalid, int family, int type, int protocol, int kern)
+{
+	bpf_set_retval(1);
+	return 0;
+}
+
+SEC("cgroup/dev")
+__description("cgroup_device bpf_set_retval success")
+__success
+int cgroup_dev_set_retval_0(struct bpf_cgroup_dev_ctx *ctx)
+{
+	bpf_set_retval(0);
+	return 1;
+}
+
+SEC("cgroup/dev")
+__description("cgroup_device bpf_set_retval valid errno")
+__success
+int cgroup_dev_set_retval_neg_maxerrno(struct bpf_cgroup_dev_ctx *ctx)
+{
+	bpf_set_retval(-4095);
+	return 1;
+}
+
+SEC("cgroup/dev")
+__description("cgroup_device bpf_set_retval invalid positive value")
+__failure __msg("should have been in [-4095, 0]")
+int cgroup_dev_set_retval_1(struct bpf_cgroup_dev_ctx *ctx)
+{
+	bpf_set_retval(1);
+	return 1;
+}
+
+SEC("cgroup/dev")
+__description("cgroup_device bpf_set_retval invalid negative value")
+__failure __msg("should have been in [-4095, 0]")
+int cgroup_dev_set_retval_neg_4096(struct bpf_cgroup_dev_ctx *ctx)
+{
+	bpf_set_retval(-4096);
+	return 1;
+}
+
+SEC("cgroup/dev")
+__description("bpf_set_retval bounds check survives state pruning")
+__failure __msg("should have been in [-4095, 0]")
+__naked int cgroup_dev_set_retval_pruning_bypass(struct bpf_cgroup_dev_ctx *ctx)
+{
+	asm volatile (
+		"call %[bpf_get_prandom_u32];"
+		"if r0 != 0 goto 1f;"
+		"r0 = r0;"
+		"r0 = r0;"
+		"r0 = r0;"
+		"r0 = r0;"
+		"goto 2f;"
+	"1:"
+		"call %[bpf_get_prandom_u32];"
+	"2:"
+		"r1 = r0;"
+		"call %[bpf_set_retval];"
+		"r0 = 1;"
+		"exit;"
+		:
+		: __imm(bpf_get_prandom_u32),
+		  __imm(bpf_set_retval)
+		: __clobber_common
+	);
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.47.3