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

[Bobby Eshleman <bobbyeshleman@gmail.com>]

On Fri, May 01, 2026 at 08:52:53AM -0700, Breno Leitao wrote:
> 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>

This all looks good to me. My only thought was
SO_VM_SOCKETS_CONNECT_TIMEOUT_NEW/OLD would be a nice add-on for testing
greater than u64, but probably overkill since you already have
NETLINK_LIST_MEMBERSHIPS.

Code all looks reasonable.

Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>

> ---
>  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
>