selftests/bpf: Add a testcase for 64-bit bounds propagation issue.

./test_progs-no_alu32 -vv -t twfw

Before the 64-bit_into_32-bit fix:
19: (25) if r1 > 0x3f goto pc+6
 R1_w=inv(id=0,umax_value=63,var_off=(0x0; 0xff),s32_max_value=255,u32_max_value=255)

and eventually:

invalid access to map value, value_size=8 off=7 size=8
R6 max value is outside of the allowed memory range
libbpf: failed to load object 'no_alu32/twfw.o'

After the fix:
19: (25) if r1 > 0x3f goto pc+6
 R1_w=inv(id=0,umax_value=63,var_off=(0x0; 0x3f))

verif_twfw:OK

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-3-alexei.starovoitov@gmail.com

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
index 867349e4ed9e3532d72d137ce8c55257397ce4e8..27f5d8ea7964d94478e4c680b1c28577d398e3c6 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
@@ -202,3 +202,8 @@ void test_verif_scale_seg6_loop()
 {
        scale_test("test_seg6_loop.o", BPF_PROG_TYPE_LWT_SEG6LOCAL, false);
 }
+
+void test_verif_twfw()
+{
+       scale_test("twfw.o", BPF_PROG_TYPE_CGROUP_SKB, false);
+}

diff --git a/tools/testing/selftests/bpf/progs/twfw.c b/tools/testing/selftests/bpf/progs/twfw.c
new file mode 100644 (file)
index 0000000..de1b18a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/twfw.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+#include <linux/types.h>
+#include <bpf/bpf_helpers.h>
+#include <linux/bpf.h>
+#include <stdint.h>
+
+#define TWFW_MAX_TIERS (64)
+/*
+ * load is successful
+ * #define TWFW_MAX_TIERS (64u)$
+ */
+
+struct twfw_tier_value {
+       unsigned long mask[1];
+};
+
+struct rule {
+       uint8_t seqnum;
+};
+
+struct rules_map {
+       __uint(type, BPF_MAP_TYPE_ARRAY);
+       __type(key, __u32);
+       __type(value, struct rule);
+       __uint(max_entries, 1);
+};
+
+struct tiers_map {
+       __uint(type, BPF_MAP_TYPE_ARRAY);
+       __type(key, __u32);
+       __type(value, struct twfw_tier_value);
+       __uint(max_entries, 1);
+};
+
+struct rules_map rules SEC(".maps");
+struct tiers_map tiers SEC(".maps");
+
+SEC("cgroup_skb/ingress")
+int twfw_verifier(struct __sk_buff* skb)
+{
+       const uint32_t key = 0;
+       const struct twfw_tier_value* tier = bpf_map_lookup_elem(&tiers, &key);
+       if (!tier)
+               return 1;
+
+       struct rule* rule = bpf_map_lookup_elem(&rules, &key);
+       if (!rule)
+               return 1;
+
+       if (rule && rule->seqnum < TWFW_MAX_TIERS) {
+               /* rule->seqnum / 64 should always be 0 */
+               unsigned long mask = tier->mask[rule->seqnum / 64];
+               if (mask)
+                       return 0;
+       }
+       return 1;
+}