bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 145 insertions, 0 deletions

diff --git a/net/ethtool/linkinfo.c b/net/ethtool/linkinfo.c
new file mode 100644
index 000000000..d5b3dbc53
--- /dev/null
+++ b/net/ethtool/linkinfo.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "common.h"
+#include "netlink.h"
+
+struct linkinfo_req_info {
+	struct ethnl_req_info		base;
+};
+
+struct linkinfo_reply_data {
+	struct ethnl_reply_data		base;
+	struct ethtool_link_ksettings	ksettings;
+	struct ethtool_link_settings	*lsettings;
+};
+
+#define LINKINFO_REPDATA(__reply_base) \
+	container_of(__reply_base, struct linkinfo_reply_data, base)
+
+const struct nla_policy ethnl_linkinfo_get_policy[] = {
+	[ETHTOOL_A_LINKINFO_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+};
+
+static int linkinfo_prepare_data(const struct ethnl_req_info *req_base,
+				 struct ethnl_reply_data *reply_base,
+				 const struct genl_info *info)
+{
+	struct linkinfo_reply_data *data = LINKINFO_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	int ret;
+
+	data->lsettings = &data->ksettings.base;
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		return ret;
+	ret = netif_get_link_ksettings(dev, &data->ksettings);
+	if (ret < 0)
+		GENL_SET_ERR_MSG(info, "failed to retrieve link settings");
+	ethnl_ops_complete(dev);
+
+	return ret;
+}
+
+static int linkinfo_reply_size(const struct ethnl_req_info *req_base,
+			       const struct ethnl_reply_data *reply_base)
+{
+	return nla_total_size(sizeof(u8)) /* LINKINFO_PORT */
+		+ nla_total_size(sizeof(u8)) /* LINKINFO_PHYADDR */
+		+ nla_total_size(sizeof(u8)) /* LINKINFO_TP_MDIX */
+		+ nla_total_size(sizeof(u8)) /* LINKINFO_TP_MDIX_CTRL */
+		+ nla_total_size(sizeof(u8)) /* LINKINFO_TRANSCEIVER */
+		+ 0;
+}
+
+static int linkinfo_fill_reply(struct sk_buff *skb,
+			       const struct ethnl_req_info *req_base,
+			       const struct ethnl_reply_data *reply_base)
+{
+	const struct linkinfo_reply_data *data = LINKINFO_REPDATA(reply_base);
+
+	if (nla_put_u8(skb, ETHTOOL_A_LINKINFO_PORT, data->lsettings->port) ||
+	    nla_put_u8(skb, ETHTOOL_A_LINKINFO_PHYADDR,
+		       data->lsettings->phy_address) ||
+	    nla_put_u8(skb, ETHTOOL_A_LINKINFO_TP_MDIX,
+		       data->lsettings->eth_tp_mdix) ||
+	    nla_put_u8(skb, ETHTOOL_A_LINKINFO_TP_MDIX_CTRL,
+		       data->lsettings->eth_tp_mdix_ctrl) ||
+	    nla_put_u8(skb, ETHTOOL_A_LINKINFO_TRANSCEIVER,
+		       data->lsettings->transceiver))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+/* LINKINFO_SET */
+
+const struct nla_policy ethnl_linkinfo_set_policy[] = {
+	[ETHTOOL_A_LINKINFO_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+	[ETHTOOL_A_LINKINFO_PORT]		= { .type = NLA_U8 },
+	[ETHTOOL_A_LINKINFO_PHYADDR]		= { .type = NLA_U8 },
+	[ETHTOOL_A_LINKINFO_TP_MDIX_CTRL]	= { .type = NLA_U8 },
+};
+
+static int
+ethnl_set_linkinfo_validate(struct ethnl_req_info *req_info,
+			    struct genl_info *info)
+{
+	const struct ethtool_ops *ops = req_info->dev->ethtool_ops;
+
+	if (!ops->get_link_ksettings || !ops->set_link_ksettings)
+		return -EOPNOTSUPP;
+	return 1;
+}
+
+static int
+ethnl_set_linkinfo(struct ethnl_req_info *req_info, struct genl_info *info)
+{
+	struct ethtool_link_ksettings ksettings = {};
+	struct ethtool_link_settings *lsettings;
+	struct net_device *dev = req_info->dev;
+	struct nlattr **tb = info->attrs;
+	bool mod = false;
+	int ret;
+
+	ret = netif_get_link_ksettings(dev, &ksettings);
+	if (ret < 0) {
+		GENL_SET_ERR_MSG(info, "failed to retrieve link settings");
+		return ret;
+	}
+	lsettings = &ksettings.base;
+
+	ethnl_update_u8(&lsettings->port, tb[ETHTOOL_A_LINKINFO_PORT], &mod);
+	ethnl_update_u8(&lsettings->phy_address, tb[ETHTOOL_A_LINKINFO_PHYADDR],
+			&mod);
+	ethnl_update_u8(&lsettings->eth_tp_mdix_ctrl,
+			tb[ETHTOOL_A_LINKINFO_TP_MDIX_CTRL], &mod);
+	if (!mod)
+		return 0;
+
+	ret = dev->ethtool_ops->set_link_ksettings(dev, &ksettings);
+	if (ret < 0) {
+		GENL_SET_ERR_MSG(info, "link settings update failed");
+		return ret;
+	}
+
+	return 1;
+}
+
+const struct ethnl_request_ops ethnl_linkinfo_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_LINKINFO_GET,
+	.reply_cmd		= ETHTOOL_MSG_LINKINFO_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_LINKINFO_HEADER,
+	.req_info_size		= sizeof(struct linkinfo_req_info),
+	.reply_data_size	= sizeof(struct linkinfo_reply_data),
+
+	.prepare_data		= linkinfo_prepare_data,
+	.reply_size		= linkinfo_reply_size,
+	.fill_reply		= linkinfo_fill_reply,
+
+	.set_validate		= ethnl_set_linkinfo_validate,
+	.set			= ethnl_set_linkinfo,
+	.set_ntf_cmd		= ETHTOOL_MSG_LINKINFO_NTF,
+};