[PATCH bpf-next v2 2/2] selftests/bpf: Add tests for accessing ifindex in bpf_sk_lookup

From: Mark Pashmfouroush
Date: Thu Nov 04 2021 - 08:23:41 EST


A new field was added to the bpf_sk_lookup data that users can access.
Add tests that validate that the new ifindex field contains the right
data.

Signed-off-by: Mark Pashmfouroush <markpash@xxxxxxxxxxxxxx>

diff --git a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
index 6db07401bc49..57846cc7ce36 100644
--- a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
+++ b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
@@ -937,6 +937,37 @@ static void test_drop_on_lookup(struct test_sk_lookup *skel)
.connect_to = { EXT_IP6, EXT_PORT },
.listen_at = { EXT_IP6, INT_PORT },
},
+ /* The program will drop on success, meaning that the ifindex
+ * was 1.
+ */
+ {
+ .desc = "TCP IPv4 drop on valid ifindex",
+ .lookup_prog = skel->progs.check_ifindex,
+ .sotype = SOCK_STREAM,
+ .connect_to = { EXT_IP4, EXT_PORT },
+ .listen_at = { EXT_IP4, EXT_PORT },
+ },
+ {
+ .desc = "TCP IPv6 drop on valid ifindex",
+ .lookup_prog = skel->progs.check_ifindex,
+ .sotype = SOCK_STREAM,
+ .connect_to = { EXT_IP6, EXT_PORT },
+ .listen_at = { EXT_IP6, EXT_PORT },
+ },
+ {
+ .desc = "UDP IPv4 drop on valid ifindex",
+ .lookup_prog = skel->progs.check_ifindex,
+ .sotype = SOCK_DGRAM,
+ .connect_to = { EXT_IP4, EXT_PORT },
+ .listen_at = { EXT_IP4, EXT_PORT },
+ },
+ {
+ .desc = "UDP IPv6 drop on valid ifindex",
+ .lookup_prog = skel->progs.check_ifindex,
+ .sotype = SOCK_DGRAM,
+ .connect_to = { EXT_IP6, EXT_PORT },
+ .listen_at = { EXT_IP6, EXT_PORT },
+ },
};
const struct test *t;

diff --git a/tools/testing/selftests/bpf/progs/test_sk_lookup.c b/tools/testing/selftests/bpf/progs/test_sk_lookup.c
index 19d2465d9442..0f3283bfe3b6 100644
--- a/tools/testing/selftests/bpf/progs/test_sk_lookup.c
+++ b/tools/testing/selftests/bpf/progs/test_sk_lookup.c
@@ -84,6 +84,14 @@ int lookup_drop(struct bpf_sk_lookup *ctx)
return SK_DROP;
}

+SEC("sk_lookup")
+int check_ifindex(struct bpf_sk_lookup *ctx)
+{
+ if (ctx->ifindex == 1)
+ return SK_DROP;
+ return SK_PASS;
+}
+
SEC("sk_reuseport")
int reuseport_pass(struct sk_reuseport_md *ctx)
{
diff --git a/tools/testing/selftests/bpf/verifier/ctx_sk_lookup.c b/tools/testing/selftests/bpf/verifier/ctx_sk_lookup.c
index d78627be060f..0b3088da1e89 100644
--- a/tools/testing/selftests/bpf/verifier/ctx_sk_lookup.c
+++ b/tools/testing/selftests/bpf/verifier/ctx_sk_lookup.c
@@ -229,6 +229,24 @@
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
offsetof(struct bpf_sk_lookup, local_port)),

+ /* 1-byte read from ifindex field */
+ BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
+ offsetof(struct bpf_sk_lookup, ifindex)),
+ BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
+ offsetof(struct bpf_sk_lookup, ifindex) + 1),
+ BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
+ offsetof(struct bpf_sk_lookup, ifindex) + 2),
+ BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
+ offsetof(struct bpf_sk_lookup, ifindex) + 3),
+ /* 2-byte read from ifindex field */
+ BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
+ offsetof(struct bpf_sk_lookup, ifindex)),
+ BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
+ offsetof(struct bpf_sk_lookup, ifindex) + 2),
+ /* 4-byte read from ifindex field */
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+ offsetof(struct bpf_sk_lookup, ifindex)),
+
/* 8-byte read from sk field */
BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
offsetof(struct bpf_sk_lookup, sk)),
@@ -351,6 +369,20 @@
.expected_attach_type = BPF_SK_LOOKUP,
.flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
},
+{
+ "invalid 8-byte read from bpf_sk_lookup ifindex field",
+ .insns = {
+ BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
+ offsetof(struct bpf_sk_lookup, ifindex)),
+ BPF_MOV32_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "invalid bpf_context access",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_SK_LOOKUP,
+ .expected_attach_type = BPF_SK_LOOKUP,
+ .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
+},
/* invalid 1,2,4-byte reads from 8-byte fields in bpf_sk_lookup */
{
"invalid 4-byte read from bpf_sk_lookup sk field",
--
2.31.1