psp: add op for rotation of device key

Rotating the device key is a key part of the PSP protocol design.
Some external daemon needs to do it once a day, or so.
Add a netlink op to perform this operation.
Add a notification group for informing users that key has been
rotated and they should rekey (next rotation will cut them off).

Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250917000954.859376-6-daniel.zahka@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

4 files changed, 59 insertions, 1 deletions

diff --git a/net/psp/psp-nl-gen.c b/net/psp/psp-nl-gen.c
index 859712e7c2c1..7f49577ac72f 100644
--- a/net/psp/psp-nl-gen.c
+++ b/net/psp/psp-nl-gen.c
@@ -21,6 +21,11 @@ static const struct nla_policy psp_dev_set_nl_policy[PSP_A_DEV_PSP_VERSIONS_ENA
 	[PSP_A_DEV_PSP_VERSIONS_ENA] = NLA_POLICY_MASK(NLA_U32, 0xf),
 };
 
+/* PSP_CMD_KEY_ROTATE - do */
+static const struct nla_policy psp_key_rotate_nl_policy[PSP_A_DEV_ID + 1] = {
+	[PSP_A_DEV_ID] = NLA_POLICY_MIN(NLA_U32, 1),
+};
+
 /* Ops table for psp */
 static const struct genl_split_ops psp_nl_ops[] = {
 	{
@@ -46,10 +51,20 @@ static const struct genl_split_ops psp_nl_ops[] = {
 		.maxattr	= PSP_A_DEV_PSP_VERSIONS_ENA,
 		.flags		= GENL_CMD_CAP_DO,
 	},
+	{
+		.cmd		= PSP_CMD_KEY_ROTATE,
+		.pre_doit	= psp_device_get_locked,
+		.doit		= psp_nl_key_rotate_doit,
+		.post_doit	= psp_device_unlock,
+		.policy		= psp_key_rotate_nl_policy,
+		.maxattr	= PSP_A_DEV_ID,
+		.flags		= GENL_CMD_CAP_DO,
+	},
 };
 
 static const struct genl_multicast_group psp_nl_mcgrps[] = {
 	[PSP_NLGRP_MGMT] = { "mgmt", },
+	[PSP_NLGRP_USE] = { "use", },
 };
 
 struct genl_family psp_nl_family __ro_after_init = {
diff --git a/net/psp/psp-nl-gen.h b/net/psp/psp-nl-gen.h
index a099686cab5d..00a2d4ec59e4 100644
--- a/net/psp/psp-nl-gen.h
+++ b/net/psp/psp-nl-gen.h
@@ -20,9 +20,11 @@ psp_device_unlock(const struct genl_split_ops *ops, struct sk_buff *skb,
 int psp_nl_dev_get_doit(struct sk_buff *skb, struct genl_info *info);
 int psp_nl_dev_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb);
 int psp_nl_dev_set_doit(struct sk_buff *skb, struct genl_info *info);
+int psp_nl_key_rotate_doit(struct sk_buff *skb, struct genl_info *info);
 
 enum {
 	PSP_NLGRP_MGMT,
+	PSP_NLGRP_USE,
 };
 
 extern struct genl_family psp_nl_family;
diff --git a/net/psp/psp_main.c b/net/psp/psp_main.c
index e09499b7b14a..f60155493afc 100644
--- a/net/psp/psp_main.c
+++ b/net/psp/psp_main.c
@@ -54,7 +54,8 @@ psp_dev_create(struct net_device *netdev,
 	int err;
 
 	if (WARN_ON(!psd_caps->versions ||
-		    !psd_ops->set_config))
+		    !psd_ops->set_config ||
+		    !psd_ops->key_rotate))
 		return ERR_PTR(-EINVAL);
 
 	psd = kzalloc(sizeof(*psd), GFP_KERNEL);
diff --git a/net/psp/psp_nl.c b/net/psp/psp_nl.c
index fda5ce800f82..75f2702c1029 100644
--- a/net/psp/psp_nl.c
+++ b/net/psp/psp_nl.c
@@ -221,3 +221,43 @@ err_free_rsp:
 	nlmsg_free(rsp);
 	return err;
 }
+
+int psp_nl_key_rotate_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	struct psp_dev *psd = info->user_ptr[0];
+	struct genl_info ntf_info;
+	struct sk_buff *ntf, *rsp;
+	int err;
+
+	rsp = psp_nl_reply_new(info);
+	if (!rsp)
+		return -ENOMEM;
+
+	genl_info_init_ntf(&ntf_info, &psp_nl_family, PSP_CMD_KEY_ROTATE_NTF);
+	ntf = psp_nl_reply_new(&ntf_info);
+	if (!ntf) {
+		err = -ENOMEM;
+		goto err_free_rsp;
+	}
+
+	if (nla_put_u32(rsp, PSP_A_DEV_ID, psd->id) ||
+	    nla_put_u32(ntf, PSP_A_DEV_ID, psd->id)) {
+		err = -EMSGSIZE;
+		goto err_free_ntf;
+	}
+
+	err = psd->ops->key_rotate(psd, info->extack);
+	if (err)
+		goto err_free_ntf;
+
+	nlmsg_end(ntf, (struct nlmsghdr *)ntf->data);
+	genlmsg_multicast_netns(&psp_nl_family, dev_net(psd->main_netdev), ntf,
+				0, PSP_NLGRP_USE, GFP_KERNEL);
+	return psp_nl_reply_send(rsp, info);
+
+err_free_ntf:
+	nlmsg_free(ntf);
+err_free_rsp:
+	nlmsg_free(rsp);
+	return err;
+}