[PATCH AUTOSEL 4.19 25/83] selftests/bpf: Test [::] -> [::1] rewrite in sys_sendmsg in test_sock_addr

Sasha Levin
2019-02-13T02:55:23Z

From: Andrey Ignatov <rdna@fb.com>

[ Upstream commit 976b4f3a4646fbf0d189caca25f91f82e4be4b5a ]

Test that sys_sendmsg BPF hook doesn't break sys_sendmsg behaviour to
rewrite destination IPv6 = [::] with [::1] (BSD'ism).

Two test cases are added:

1) User passes dst IPv6 = [::] and BPF_CGROUP_UDP6_SENDMSG program
doesn't touch it.

2) User passes dst IPv6 != [::], but BPF_CGROUP_UDP6_SENDMSG program
rewrites it with [::].

In both cases [::1] is used by sys_sendmsg code eventually and datagram
is sent successfully for unconnected UDP socket.

Example of relevant output:
Test case: sendmsg6: set dst IP = [::] (BSD'ism) .. [PASS]
Test case: sendmsg6: preserve dst IP = [::] (BSD'ism) .. [PASS]

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/bpf/test_sock_addr.c | 53 ++++++++++++++++++--
1 file changed, 50 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_sock_addr.c b/tools/testing/selftests/bpf/test_sock_addr.c
index aeeb76a54d63..e38f1cb7089d 100644
--- a/tools/testing/selftests/bpf/test_sock_addr.c
+++ b/tools/testing/selftests/bpf/test_sock_addr.c
@@ -44,6 +44,7 @@
#define SERV6_V4MAPPED_IP "::ffff:192.168.0.4"
#define SRC6_IP "::1"
#define SRC6_REWRITE_IP "::6"
+#define WILDCARD6_IP "::"
#define SERV6_PORT 6060
#define SERV6_REWRITE_PORT 6666

@@ -85,12 +86,14 @@ static int bind4_prog_load(const struct sock_addr_test *test);
static int bind6_prog_load(const struct sock_addr_test *test);
static int connect4_prog_load(const struct sock_addr_test *test);
static int connect6_prog_load(const struct sock_addr_test *test);
+static int sendmsg_allow_prog_load(const struct sock_addr_test *test);
static int sendmsg_deny_prog_load(const struct sock_addr_test *test);
static int sendmsg4_rw_asm_prog_load(const struct sock_addr_test *test);
static int sendmsg4_rw_c_prog_load(const struct sock_addr_test *test);
static int sendmsg6_rw_asm_prog_load(const struct sock_addr_test *test);
static int sendmsg6_rw_c_prog_load(const struct sock_addr_test *test);
static int sendmsg6_rw_v4mapped_prog_load(const struct sock_addr_test *test);
+static int sendmsg6_rw_wildcard_prog_load(const struct sock_addr_test *test);

static struct sock_addr_test tests[] = {
/* bind */
@@ -462,6 +465,34 @@ static struct sock_addr_test tests[] = {
SRC6_REWRITE_IP,
SYSCALL_ENOTSUPP,
},
+ {
+ "sendmsg6: set dst IP = [::] (BSD'ism)",
+ sendmsg6_rw_wildcard_prog_load,
+ BPF_CGROUP_UDP6_SENDMSG,
+ BPF_CGROUP_UDP6_SENDMSG,
+ AF_INET6,
+ SOCK_DGRAM,
+ SERV6_IP,
+ SERV6_PORT,
+ SERV6_REWRITE_IP,
+ SERV6_REWRITE_PORT,
+ SRC6_REWRITE_IP,
+ SUCCESS,
+ },
+ {
+ "sendmsg6: preserve dst IP = [::] (BSD'ism)",
+ sendmsg_allow_prog_load,
+ BPF_CGROUP_UDP6_SENDMSG,
+ BPF_CGROUP_UDP6_SENDMSG,
+ AF_INET6,
+ SOCK_DGRAM,
+ WILDCARD6_IP,
+ SERV6_PORT,
+ SERV6_REWRITE_IP,
+ SERV6_PORT,
+ SRC6_IP,
+ SUCCESS,
+ },
{
"sendmsg6: deny call",
sendmsg_deny_prog_load,
@@ -714,16 +745,27 @@ static int connect6_prog_load(const struct sock_addr_test *test)
return load_path(test, CONNECT6_PROG_PATH);
}

-static int sendmsg_deny_prog_load(const struct sock_addr_test *test)
+static int sendmsg_ret_only_prog_load(const struct sock_addr_test *test,
+ int32_t rc)
{
struct bpf_insn insns[] = {
- /* return 0 */
- BPF_MOV64_IMM(BPF_REG_0, 0),
+ /* return rc */
+ BPF_MOV64_IMM(BPF_REG_0, rc),
BPF_EXIT_INSN(),
};
return load_insns(test, insns, sizeof(insns) / sizeof(struct bpf_insn));
}

+static int sendmsg_allow_prog_load(const struct sock_addr_test *test)
+{
+ return sendmsg_ret_only_prog_load(test, /*rc*/ 1);
+}
+
+static int sendmsg_deny_prog_load(const struct sock_addr_test *test)
+{
+ return sendmsg_ret_only_prog_load(test, /*rc*/ 0);
+}
+
static int sendmsg4_rw_asm_prog_load(const struct sock_addr_test *test)
{
struct sockaddr_in dst4_rw_addr;
@@ -844,6 +886,11 @@ static int sendmsg6_rw_v4mapped_prog_load(const struct sock_addr_test *test)
return sendmsg6_rw_dst_asm_prog_load(test, SERV6_V4MAPPED_IP);
}

+static int sendmsg6_rw_wildcard_prog_load(const struct sock_addr_test *test)
+{
+ return sendmsg6_rw_dst_asm_prog_load(test, WILDCARD6_IP);
+}
+
static int sendmsg6_rw_c_prog_load(const struct sock_addr_test *test)
{
return load_path(test, SENDMSG6_PROG_PATH);
--
2.19.1