selftests/bpf: Add tests for bpf_set_retval validation

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

Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> #v1
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20260605140243.664590-4-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index 219ff29698687355b5ab8d26d51dca8dcf03713d..89779d897abae0ff7ba6131247dedeb8a7b65c9f 100644 (file)
--- 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 (file)
index 0000000..1415cd1
--- /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";