From ca0f587c029afa66227f7b932450b1c417403394 Mon Sep 17 00:00:00 2001 From: Leon Hwang Date: Sun, 14 Jun 2026 00:24:42 +0800 Subject: [PATCH 1/2] bpf: Fix bpf_get/setsockopt to tos for ipv4-mapped ipv6 socket When TCP over IPv4 via INET6 API, bpf_get/setsockopt with ipv4 will fail, because sk->sk_family is AF_INET6. With ipv6 will success, not take effect, because inet_csk(sk)->icsk_af_ops is ipv6_mapped and use ip_queue_xmit, inet_sk(sk)->tos. To relax this restriction, allow getting/setting tos for those possible ipv4-mapped ipv6 sockets. Fixes: ee7f1e1302f5 ("bpf: Change bpf_setsockopt(SOL_IP) to reuse do_ip_setsockopt()") Signed-off-by: Feng Zhou Signed-off-by: Leon Hwang Link: https://lore.kernel.org/r/20260613162443.60515-2-leon.hwang@linux.dev Signed-off-by: Alexei Starovoitov --- net/core/filter.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/net/core/filter.c b/net/core/filter.c index 9590877b0714..57b00c6cc8cc 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5544,11 +5544,24 @@ static int sol_tcp_sockopt(struct sock *sk, int optname, KERNEL_SOCKPTR(optval), *optlen); } +static bool sk_allows_sol_ip_sockopt(struct sock *sk) +{ + switch (sk->sk_family) { + case AF_INET: + return true; + case AF_INET6: + /* Allow getting/setting sockopt for possible ipv4-mapped ipv6 socket. */ + return sk->sk_type != SOCK_RAW && !ipv6_only_sock(sk); + default: + return false; + } +} + static int sol_ip_sockopt(struct sock *sk, int optname, char *optval, int *optlen, bool getopt) { - if (sk->sk_family != AF_INET) + if (!sk_allows_sol_ip_sockopt(sk)) return -EINVAL; switch (optname) { From 5cf2c21ab0900b41c0e29c925b9a640a92340d40 Mon Sep 17 00:00:00 2001 From: Leon Hwang Date: Sun, 14 Jun 2026 00:24:43 +0800 Subject: [PATCH 2/2] selftests/bpf: Add test to verify the fix for bpf_setsockopt() helper Verify the fix by: 1. Attach cgroup sockops prog. 2. Build a tcp connection using ipv4 addr in ipv6 socket. 3. Verify the return value of bpf_setsockopt() helper. Assisted-by: Codex:gpt-5.5-xhigh Signed-off-by: Leon Hwang Link: https://lore.kernel.org/r/20260613162443.60515-3-leon.hwang@linux.dev Signed-off-by: Alexei Starovoitov --- .../selftests/bpf/prog_tests/setget_sockopt.c | 78 +++++++++++++++++++ .../selftests/bpf/progs/setget_sockopt.c | 23 ++++++ 2 files changed, 101 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/setget_sockopt.c b/tools/testing/selftests/bpf/prog_tests/setget_sockopt.c index 77fe1bfb7504..4e91d9b615ce 100644 --- a/tools/testing/selftests/bpf/prog_tests/setget_sockopt.c +++ b/tools/testing/selftests/bpf/prog_tests/setget_sockopt.c @@ -199,6 +199,83 @@ static void test_nonstandard_opt(int family) bpf_link__destroy(getsockopt_link); } +static int connect_to_v4mapped_v6_fd(int server_fd) +{ + struct sockaddr_storage addr; + struct sockaddr_in *addr4 = (void *)&addr; + socklen_t addrlen = sizeof(addr); + struct sockaddr_in6 addr6 = {}; + int fd = -1, v6only = 0, err; + + err = getsockname(server_fd, (struct sockaddr *)&addr, &addrlen); + if (!ASSERT_OK(err, "getsockname")) + return -1; + + fd = socket(AF_INET6, SOCK_STREAM, 0); + if (!ASSERT_GE(fd, 0, "socket")) + return -1; + + err = settimeo(fd, 0); + if (!ASSERT_OK(err, "settimeo")) + goto err_out; + + err = setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &v6only, sizeof(v6only)); + if (!ASSERT_OK(err, "clear_v6only")) + goto err_out; + + addr6.sin6_family = AF_INET6; + addr6.sin6_port = addr4->sin_port; + addr6.sin6_addr.s6_addr[10] = 0xff; + addr6.sin6_addr.s6_addr[11] = 0xff; + memcpy(&addr6.sin6_addr.s6_addr[12], &addr4->sin_addr, sizeof(addr4->sin_addr)); + + err = connect(fd, (struct sockaddr *)&addr6, sizeof(addr6)); + if (!ASSERT_OK(err, "connect")) + goto err_out; + + return fd; + +err_out: + close(fd); + return -1; +} + +static void test_v4mapped_v6_ip_tos(void) +{ + struct setget_sockopt__bss *bss = skel->bss; + int sfd = -1, fd = -1, got = 0, exp = 0x1c; + socklen_t optlen; + + memset(bss, 0, sizeof(*bss)); + bss->v4mapped_v6_ip_tos_enable = 1; + bss->v4mapped_v6_ip_tos_ret = -1; + bss->v4mapped_v6_ip_tos_val = exp; + + sfd = start_server(AF_INET, SOCK_STREAM, addr4_str, 0, 0); + if (!ASSERT_GE(sfd, 0, "start_server")) + goto err_out; + + fd = connect_to_v4mapped_v6_fd(sfd); + if (!ASSERT_GE(fd, 0, "connect_to_v4mapped_v6_fd")) + goto err_out; + + ASSERT_GT(bss->v4mapped_v6_ip_tos_cnt, 0, "v4mapped_v6_ip_tos_cnt"); + ASSERT_EQ(bss->v4mapped_v6_ip_tos_ret, 0, "v4mapped_v6_ip_tos_ret"); + + optlen = sizeof(got); + if (!ASSERT_OK(getsockopt(fd, SOL_IP, IP_TOS, &got, &optlen), "getsockopt_ip_tos")) + goto err_out; + + ASSERT_EQ(got, exp, "ip_tos"); + +err_out: + bss->v4mapped_v6_ip_tos_enable = 0; + if (fd >= 0) + close(fd); + if (sfd >= 0) + close(sfd); +} + void test_setget_sockopt(void) { cg_fd = test__join_cgroup(CG_NAME); @@ -238,6 +315,7 @@ void test_setget_sockopt(void) test_ktls(AF_INET); test_nonstandard_opt(AF_INET); test_nonstandard_opt(AF_INET6); + test_v4mapped_v6_ip_tos(); done: setget_sockopt__destroy(skel); diff --git a/tools/testing/selftests/bpf/progs/setget_sockopt.c b/tools/testing/selftests/bpf/progs/setget_sockopt.c index d330b1511979..636a7cd8e2fa 100644 --- a/tools/testing/selftests/bpf/progs/setget_sockopt.c +++ b/tools/testing/selftests/bpf/progs/setget_sockopt.c @@ -387,6 +387,24 @@ int _getsockopt(struct bpf_sockopt *ctx) return 1; } +int v4mapped_v6_ip_tos_enable; +int v4mapped_v6_ip_tos_ret; +int v4mapped_v6_ip_tos_cnt; +int v4mapped_v6_ip_tos_val; + +static void test_v4mapped_v6_ip_tos(struct bpf_sock_ops *skops) +{ + int tos = v4mapped_v6_ip_tos_val; + + if (!v4mapped_v6_ip_tos_enable || skops->op != BPF_SOCK_OPS_TCP_CONNECT_CB) + return; + if (skops->family != AF_INET6) + return; + + v4mapped_v6_ip_tos_cnt++; + v4mapped_v6_ip_tos_ret = bpf_setsockopt(skops, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)); +} + SEC("sockops") int skops_sockopt(struct bpf_sock_ops *skops) { @@ -401,6 +419,11 @@ int skops_sockopt(struct bpf_sock_ops *skops) if (!sk) return 1; + if (v4mapped_v6_ip_tos_enable) { + test_v4mapped_v6_ip_tos(skops); + return 1; + } + switch (skops->op) { case BPF_SOCK_OPS_TCP_LISTEN_CB: nr_listen += !(bpf_test_sockopt(skops, sk) ||