[PATCH net-next 3/3] net: selftests: add getsockopt_iter regression tests

Breno Leitao
2026-05-01T15:53:23Z

Add a single kselftest covering the proto_ops getsockopt_iter
conversions for AF_NETLINK and AF_VSOCK, using one fixture per protocol:

netlink:

NETLINK_PKTINFO covers the flag-style int path (exact size, oversize
clamp, undersize -EINVAL); NETLINK_LIST_MEMBERSHIPS covers the
size-discovery path that always reports the required buffer length back
via optlen, even when the user buffer is too small to receive any group
bits.

vsock:
SO_VM_SOCKETS_BUFFER_SIZE covers the u64 path (exact size, oversize
clamp, undersize -EINVAL).

Each fixture also exercises an unknown optname and a bogus level so
the returned-length / errno semantics preserved by the sockopt_t
conversion are pinned down.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
tools/testing/selftests/net/Makefile | 1 +
tools/testing/selftests/net/getsockopt_iter.c | 213 ++++++++++++++++++++++++++
2 files changed, 214 insertions(+)

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index a275ed5840265..baa30287cf222 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -176,6 +176,7 @@ TEST_GEN_PROGS := \
bind_timewait \
bind_wildcard \
epoll_busy_poll \
+ getsockopt_iter \
icmp_rfc4884 \
ipv6_fragmentation \
proc_net_pktgen \
diff --git a/tools/testing/selftests/net/getsockopt_iter.c b/tools/testing/selftests/net/getsockopt_iter.c
new file mode 100644
index 0000000000000..179f9e84926fd
--- /dev/null
+++ b/tools/testing/selftests/net/getsockopt_iter.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Quick test for getsockopt{_iter} tests.
+ *
+ * Each fixture targets one converted protocol and pins down the
+ * returned-length / errno semantics across buffer-size variations,
+ * an unknown optname and a bogus level.
+ *
+ * - netlink: NETLINK_PKTINFO covers the flag-style int path; the
+ * NETLINK_LIST_MEMBERSHIPS cases cover the size-discovery path
+ * that always reports the required buffer length back via optlen,
+ * even when the user buffer is too small to receive any group bits.
+ * - vsock: SO_VM_SOCKETS_BUFFER_SIZE covers the u64 path.
+ *
+ * Author: Breno Leitao <leitao@debian.org>
+ */
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/vm_sockets.h>
+#include <sys/socket.h>
+#include "kselftest_harness.h"
+
+#ifndef AF_VSOCK
+#define AF_VSOCK 40
+#endif
+
+/* ---------- netlink ---------- */
+
+FIXTURE(netlink)
+{
+ int fd;
+};
+
+FIXTURE_SETUP(netlink)
+{
+ int group = RTNLGRP_LINK;
+
+ self->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+ if (self->fd < 0)
+ SKIP(return, "AF_NETLINK socket: %s", strerror(errno));
+
+ /* Joining a multicast group grows nlk->ngroups so the
+ * NETLINK_LIST_MEMBERSHIPS path has a non-zero size to report.
+ */
+ if (setsockopt(self->fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
+ &group, sizeof(group)) < 0)
+ SKIP(return, "NETLINK_ADD_MEMBERSHIP: %s", strerror(errno));
+}
+
+FIXTURE_TEARDOWN(netlink)
+{
+ if (self->fd >= 0)
+ close(self->fd);
+}
+
+TEST_F(netlink, pktinfo_exact)
+{
+ int val = -1;
+ socklen_t optlen = sizeof(val);
+
+ ASSERT_EQ(0, getsockopt(self->fd, SOL_NETLINK, NETLINK_PKTINFO,
+ &val, &optlen));
+ ASSERT_EQ(sizeof(int), optlen);
+ ASSERT_TRUE(val == 0 || val == 1);
+}
+
+TEST_F(netlink, pktinfo_oversize_clamped)
+{
+ char buf[16] = {};
+ socklen_t optlen = sizeof(buf);
+
+ ASSERT_EQ(0, getsockopt(self->fd, SOL_NETLINK, NETLINK_PKTINFO,
+ buf, &optlen));
+ ASSERT_EQ(sizeof(int), optlen);
+}
+
+TEST_F(netlink, pktinfo_undersize)
+{
+ char buf[2] = {};
+ socklen_t optlen = sizeof(buf);
+
+ ASSERT_EQ(-1, getsockopt(self->fd, SOL_NETLINK, NETLINK_PKTINFO,
+ buf, &optlen));
+ ASSERT_EQ(EINVAL, errno);
+}
+
+TEST_F(netlink, list_memberships_size_discovery)
+{
+ socklen_t optlen = 0;
+ char dummy;
+
+ ASSERT_EQ(0, getsockopt(self->fd, SOL_NETLINK,
+ NETLINK_LIST_MEMBERSHIPS,
+ &dummy, &optlen));
+ ASSERT_GT(optlen, 0);
+ ASSERT_EQ(0, optlen % sizeof(__u32));
+}
+
+TEST_F(netlink, list_memberships_full_read)
+{
+ __u32 buf[64] = {};
+ socklen_t optlen = sizeof(buf);
+
+ ASSERT_EQ(0, getsockopt(self->fd, SOL_NETLINK,
+ NETLINK_LIST_MEMBERSHIPS,
+ buf, &optlen));
+ ASSERT_GT(optlen, 0);
+ ASSERT_LE(optlen, sizeof(buf));
+ ASSERT_EQ(0, optlen % sizeof(__u32));
+}
+
+TEST_F(netlink, bad_level)
+{
+ int val;
+ socklen_t optlen = sizeof(val);
+
+ ASSERT_EQ(-1, getsockopt(self->fd, SOL_SOCKET + 1, NETLINK_PKTINFO,
+ &val, &optlen));
+ ASSERT_EQ(ENOPROTOOPT, errno);
+}
+
+TEST_F(netlink, bad_optname)
+{
+ int val;
+ socklen_t optlen = sizeof(val);
+
+ ASSERT_EQ(-1, getsockopt(self->fd, SOL_NETLINK, 0x7fff,
+ &val, &optlen));
+ ASSERT_EQ(ENOPROTOOPT, errno);
+}
+
+/* ---------- vsock ---------- */
+
+FIXTURE(vsock)
+{
+ int fd;
+};
+
+FIXTURE_SETUP(vsock)
+{
+ self->fd = socket(AF_VSOCK, SOCK_STREAM, 0);
+ if (self->fd < 0)
+ SKIP(return, "AF_VSOCK socket: %s", strerror(errno));
+}
+
+FIXTURE_TEARDOWN(vsock)
+{
+ if (self->fd >= 0)
+ close(self->fd);
+}
+
+TEST_F(vsock, buffer_size_exact)
+{
+ uint64_t val = 0;
+ socklen_t optlen = sizeof(val);
+
+ ASSERT_EQ(0, getsockopt(self->fd, AF_VSOCK,
+ SO_VM_SOCKETS_BUFFER_SIZE,
+ &val, &optlen));
+ ASSERT_EQ(sizeof(uint64_t), optlen);
+ ASSERT_GT(val, 0);
+}
+
+TEST_F(vsock, buffer_size_oversize_clamped)
+{
+ char buf[16] = {};
+ socklen_t optlen = sizeof(buf);
+
+ ASSERT_EQ(0, getsockopt(self->fd, AF_VSOCK,
+ SO_VM_SOCKETS_BUFFER_SIZE,
+ buf, &optlen));
+ ASSERT_EQ(sizeof(uint64_t), optlen);
+}
+
+TEST_F(vsock, buffer_size_undersize)
+{
+ char buf[4] = {};
+ socklen_t optlen = sizeof(buf);
+
+ ASSERT_EQ(-1, getsockopt(self->fd, AF_VSOCK,
+ SO_VM_SOCKETS_BUFFER_SIZE,
+ buf, &optlen));
+ ASSERT_EQ(EINVAL, errno);
+}
+
+TEST_F(vsock, bad_level)
+{
+ uint64_t val;
+ socklen_t optlen = sizeof(val);
+
+ ASSERT_EQ(-1, getsockopt(self->fd, SOL_SOCKET + 1,
+ SO_VM_SOCKETS_BUFFER_SIZE,
+ &val, &optlen));
+ ASSERT_EQ(ENOPROTOOPT, errno);
+}
+
+TEST_F(vsock, bad_optname)
+{
+ uint64_t val;
+ socklen_t optlen = sizeof(val);
+
+ ASSERT_EQ(-1, getsockopt(self->fd, AF_VSOCK, 0x7fff,
+ &val, &optlen));
+ ASSERT_EQ(ENOPROTOOPT, errno);
+}
+
+TEST_HARNESS_MAIN

--
2.52.0