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);