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, 60 insertions, 0 deletions

diff --git a/net/handshake/genl.c b/net/handshake/genl.c
new file mode 100644
index 000000000..feac1ad06
--- /dev/null
+++ b/net/handshake/genl.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/handshake.yaml */
+/* YNL-GEN kernel source */
+/* To regenerate run: tools/net/ynl/ynl-regen.sh */
+
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+#include "genl.h"
+
+#include <uapi/linux/handshake.h>
+#include <linux/err.h>
+
+/* HANDSHAKE_CMD_ACCEPT - do */
+static const struct nla_policy handshake_accept_nl_policy[HANDSHAKE_A_ACCEPT_HANDLER_CLASS + 1] = {
+	[HANDSHAKE_A_ACCEPT_HANDLER_CLASS] = NLA_POLICY_MAX(NLA_U32, 2),
+};
+
+/* HANDSHAKE_CMD_DONE - do */
+static const struct nla_policy handshake_done_nl_policy[HANDSHAKE_A_DONE_REMOTE_AUTH + 1] = {
+	[HANDSHAKE_A_DONE_STATUS] = NLA_POLICY_MAX(NLA_U32, MAX_ERRNO),
+	[HANDSHAKE_A_DONE_SOCKFD] = { .type = NLA_S32, },
+	[HANDSHAKE_A_DONE_REMOTE_AUTH] = { .type = NLA_U32, },
+};
+
+/* Ops table for handshake */
+static const struct genl_split_ops handshake_nl_ops[] = {
+	{
+		.cmd		= HANDSHAKE_CMD_ACCEPT,
+		.doit		= handshake_nl_accept_doit,
+		.policy		= handshake_accept_nl_policy,
+		.maxattr	= HANDSHAKE_A_ACCEPT_HANDLER_CLASS,
+		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd		= HANDSHAKE_CMD_DONE,
+		.doit		= handshake_nl_done_doit,
+		.policy		= handshake_done_nl_policy,
+		.maxattr	= HANDSHAKE_A_DONE_REMOTE_AUTH,
+		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+};
+
+static const struct genl_multicast_group handshake_nl_mcgrps[] = {
+	[HANDSHAKE_NLGRP_NONE] = { "none", },
+	[HANDSHAKE_NLGRP_TLSHD] = { "tlshd", },
+};
+
+struct genl_family handshake_nl_family __ro_after_init = {
+	.name		= HANDSHAKE_FAMILY_NAME,
+	.version	= HANDSHAKE_FAMILY_VERSION,
+	.netnsok	= true,
+	.parallel_ops	= true,
+	.module		= THIS_MODULE,
+	.split_ops	= handshake_nl_ops,
+	.n_split_ops	= ARRAY_SIZE(handshake_nl_ops),
+	.mcgrps		= handshake_nl_mcgrps,
+	.n_mcgrps	= ARRAY_SIZE(handshake_nl_mcgrps),
+};