[RFC net-next 05/15] psp: add op for rotation of secret state

Jakub Kicinski
2024-05-10T03:04:48Z

Rotating the secret state 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).

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
Documentation/netlink/specs/psp.yaml | 21 +++++++++++++++
include/net/psp/types.h | 5 ++++
include/uapi/linux/psp.h | 3 +++
net/psp/psp-nl-gen.c | 15 +++++++++++
net/psp/psp-nl-gen.h | 2 ++
net/psp/psp_main.c | 3 ++-
net/psp/psp_nl.c | 40 ++++++++++++++++++++++++++++
7 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/psp.yaml b/Documentation/netlink/specs/psp.yaml
index dbb5ef148045..6ae598a60b3f 100644
--- a/Documentation/netlink/specs/psp.yaml
+++ b/Documentation/netlink/specs/psp.yaml
@@ -88,7 +88,28 @@ name: psp
notify: dev-get
mcgrp: mgmt

+ -
+ name: key-rotate
+ doc: Rotate the secret state.
+ attribute-set: dev
+ do:
+ request:
+ attributes:
+ - id
+ reply:
+ attributes:
+ - id
+ pre: psp-device-get-locked
+ post: psp-device-unlock
+ -
+ name: key-rotate-ntf
+ doc: Notification about secret state getting rotated.
+ notify: key-rotate
+ mcgrp: use
+
mcast-groups:
list:
-
name: mgmt
+ -
+ name: use
diff --git a/include/net/psp/types.h b/include/net/psp/types.h
index a23d9bd9ce96..43950caf70f1 100644
--- a/include/net/psp/types.h
+++ b/include/net/psp/types.h
@@ -104,6 +104,11 @@ struct psp_dev_ops {
*/
int (*set_config)(struct psp_dev *psd, struct psp_dev_config *conf,
struct netlink_ext_ack *extack);
+
+ /**
+ * @key_rotate: rotate the secret state
+ */
+ int (*key_rotate)(struct psp_dev *psd, struct netlink_ext_ack *extack);
};

#endif /* __NET_PSP_H */
diff --git a/include/uapi/linux/psp.h b/include/uapi/linux/psp.h
index 4a404f085190..cbfbf3f0f364 100644
--- a/include/uapi/linux/psp.h
+++ b/include/uapi/linux/psp.h
@@ -32,11 +32,14 @@ enum {
PSP_CMD_DEV_DEL_NTF,
PSP_CMD_DEV_SET,
PSP_CMD_DEV_CHANGE_NTF,
+ PSP_CMD_KEY_ROTATE,
+ PSP_CMD_KEY_ROTATE_NTF,

__PSP_CMD_MAX,
PSP_CMD_MAX = (__PSP_CMD_MAX - 1)
};

#define PSP_MCGRP_MGMT "mgmt"
+#define PSP_MCGRP_USE "use"

#endif /* _UAPI_LINUX_PSP_H */
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 cf463f757892..536f50d82fb2 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..b7006e50dc87 100644
--- a/net/psp/psp_nl.c
+++ b/net/psp/psp_nl.c
@@ -221,3 +221,43 @@ int psp_nl_dev_set_doit(struct sk_buff *skb, struct genl_info *info)
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 = 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;
+}
--
2.45.0