[PATCH v5 08/15] coco: host: arm64: Register device public key with RMM
Aneesh Kumar K.V (Arm)
aneesh.kumar at kernel.org
Thu Sep 10 07:05:01 PDT 2026
- Introduce the SMC_RMI_PDEV_SET_PUBKEY helper and the associated struct
rmi_public_key_params so the host can hand the device’s public key to
the RMM.
- Parse the certificate chain cached during SPDM session setup, extract the
final certificate’s public key, and recognise RSA-3072, ECDSA-P256, and
ECDSA-P384 keys before calling into the RMM.
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar at kernel.org>
---
drivers/virt/coco/arm-cca-host/Kconfig | 7 ++
drivers/virt/coco/arm-cca-host/rmi-da.c | 152 ++++++++++++++++++++++++
drivers/virt/coco/arm-cca-host/rmi-da.h | 2 +
include/linux/arm-rmi-cmds.h | 9 ++
include/linux/arm-smccc-rmi.h | 18 +++
5 files changed, 188 insertions(+)
diff --git a/drivers/virt/coco/arm-cca-host/Kconfig b/drivers/virt/coco/arm-cca-host/Kconfig
index d2bf44f9776a..43f0f0228e0c 100644
--- a/drivers/virt/coco/arm-cca-host/Kconfig
+++ b/drivers/virt/coco/arm-cca-host/Kconfig
@@ -9,6 +9,13 @@ config ARM_CCA_HOST
depends on ARM_RMM_RMI
depends on HAVE_ARM_SMCCC_DISCOVERY
select PCI_TSM
+ select KEYS
+ select ASYMMETRIC_KEY_TYPE
+ select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+ select CRYPTO
+ select X509_CERTIFICATE_PARSER
+ select CRYPTO_ECDSA
+ select CRYPTO_RSA
help
ARM CCA RMM firmware is the trusted runtime that enforces memory
diff --git a/drivers/virt/coco/arm-cca-host/rmi-da.c b/drivers/virt/coco/arm-cca-host/rmi-da.c
index 7a72e8eead90..394b6a87f2d3 100644
--- a/drivers/virt/coco/arm-cca-host/rmi-da.c
+++ b/drivers/virt/coco/arm-cca-host/rmi-da.c
@@ -8,6 +8,9 @@
#include <linux/pci-ecam.h>
#include <linux/pci-doe.h>
#include <linux/delay.h>
+#include <crypto/internal/rsa.h>
+#include <keys/asymmetric-type.h>
+#include <keys/x509-parser.h>
#include "rmi-da.h"
@@ -378,6 +381,154 @@ static int wait_for_pdev_state(struct pci_tsm *tsm, enum rmi_pdev_state target_s
return wait_for_dev_state(PDEV_COMMUNICATE, tsm, target_state, RMI_PDEV_ERROR);
}
+static int __maybe_unused parse_certificate_chain(struct pci_tsm *tsm)
+{
+ struct cca_host_pf0_ep_dsc *pf0_ep_dsc;
+ unsigned int chain_size;
+ unsigned int offset = 0;
+ u8 *chain_data;
+
+ pf0_ep_dsc = to_cca_pf0_ep_dsc(tsm->pdev);
+
+ /* If device communication didn't results in certificate caching. */
+ if (!pf0_ep_dsc->cert_chain.cache || !pf0_ep_dsc->cert_chain.cache->offset)
+ return -EINVAL;
+
+ chain_size = pf0_ep_dsc->cert_chain.cache->offset;
+ chain_data = pf0_ep_dsc->cert_chain.cache->buf;
+
+ while (offset < chain_size) {
+ ssize_t cert_len =
+ x509_get_certificate_length(chain_data + offset,
+ chain_size - offset);
+ if (cert_len < 0)
+ return cert_len;
+
+ struct x509_certificate *cert __free(x509_free_certificate) =
+ x509_cert_parse(chain_data + offset, cert_len);
+
+ if (IS_ERR(cert)) {
+ pci_warn(tsm->pdev, "parsing of certificate chain not successful\n");
+ return PTR_ERR(cert);
+ }
+
+ /* The key in the last cert in the chain is used */
+ if (offset + cert_len == chain_size) {
+ char *signature_algorithm __free(kfree) = NULL;
+ void *public_key __free(kfree) =
+ kzalloc(cert->pub->keylen, GFP_KERNEL);
+
+ if (!public_key)
+ return -ENOMEM;
+
+ if (!strcmp("rsa", cert->pub->pkey_algo)) {
+ struct rsa_key rsa_key = {0};
+ size_t skip = 0;
+ int ret;
+
+ ret = rsa_parse_pub_key(&rsa_key, cert->pub->key,
+ cert->pub->keylen);
+ if (ret)
+ return ret;
+
+ while (skip < rsa_key.n_sz && !rsa_key.n[skip])
+ skip++;
+
+ /* check we have 3072 bits len */
+ if ((rsa_key.n_sz - skip) != (3072 >> 3))
+ return -EINVAL;
+ } else if (strcmp("ecdsa-nist-p256", cert->pub->pkey_algo) &&
+ strcmp("ecdsa-nist-p384", cert->pub->pkey_algo)) {
+ return -EINVAL;
+ }
+
+ signature_algorithm = kstrdup(cert->pub->pkey_algo, GFP_KERNEL);
+ if (!signature_algorithm)
+ return -ENOMEM;
+
+ memcpy(public_key, cert->pub->key, cert->pub->keylen);
+ pf0_ep_dsc->rmi_signature_algorithm =
+ no_free_ptr(signature_algorithm);
+ pf0_ep_dsc->cert_chain.public_key = no_free_ptr(public_key);
+ pf0_ep_dsc->cert_chain.public_key_size = cert->pub->keylen;
+ pf0_ep_dsc->cert_chain.valid = true;
+ return 0;
+ }
+
+ offset += cert_len;
+ }
+
+ /* something wrong with chain size and parsing. */
+ return -EINVAL;
+}
+
+static inline void key_param_free(struct rmi_public_key_params *param)
+{
+ return free_page((unsigned long)param);
+}
+
+static inline int copy_key_part(u8 *buf, const u8 *key_buf, size_t sz)
+{
+ int skip;
+
+ /* skip leading zero in asn.1 */
+ for (skip = 0; skip < sz; skip++)
+ if (key_buf[skip])
+ break;
+
+ memcpy(buf, key_buf + skip, sz - skip);
+ return sz - skip;
+}
+
+DEFINE_FREE(key_param_free, struct rmi_public_key_params *, if (_T) key_param_free(_T))
+static int __maybe_unused pdev_set_public_key(struct pci_tsm *tsm)
+{
+ struct cca_host_pf0_ep_dsc *pf0_ep_dsc;
+
+ pf0_ep_dsc = to_cca_pf0_ep_dsc(tsm->pdev);
+ /* Check that all the necessary information was captured from communication */
+ if (!pf0_ep_dsc->cert_chain.valid)
+ return -EINVAL;
+
+ u8 *key __free(free_page) = (u8 *)get_zeroed_page(GFP_KERNEL);
+ u8 *metadata __free(free_page) = (u8 *)get_zeroed_page(GFP_KERNEL);
+ struct rmi_public_key_params *key_params __free(key_param_free) =
+ (struct rmi_public_key_params *)get_zeroed_page(GFP_KERNEL);
+ if (!key_params || !key || !metadata)
+ return -ENOMEM;
+
+ if (!strcmp("ecdsa-nist-p384", pf0_ep_dsc->rmi_signature_algorithm) ||
+ !strcmp("ecdsa-nist-p256", pf0_ep_dsc->rmi_signature_algorithm)) {
+ key_params->key_len = pf0_ep_dsc->cert_chain.public_key_size;
+ memcpy(key, pf0_ep_dsc->cert_chain.public_key,
+ pf0_ep_dsc->cert_chain.public_key_size);
+ key_params->metadata_len = 0;
+ } else if (!strcmp("rsa", pf0_ep_dsc->rmi_signature_algorithm)) {
+ int ret;
+ struct rsa_key rsa_key = {0};
+
+ ret = rsa_parse_pub_key(&rsa_key,
+ pf0_ep_dsc->cert_chain.public_key,
+ pf0_ep_dsc->cert_chain.public_key_size);
+ if (ret)
+ return ret;
+
+ key_params->key_len = copy_key_part(key, rsa_key.n, rsa_key.n_sz);
+ key_params->metadata_len = copy_key_part(metadata,
+ rsa_key.e, rsa_key.e_sz);
+ } else {
+ return -EINVAL;
+ }
+
+ key_params->key_addr = virt_to_phys(key);
+ key_params->metadata_addr = virt_to_phys(metadata);
+
+ if (rmi_pdev_set_pubkey(virt_to_phys(pf0_ep_dsc->pdev.rmm_pdev),
+ virt_to_phys(key_params)))
+ return -ENXIO;
+ return 0;
+}
+
static void pdev_state_transition_workfn(struct work_struct *work)
{
unsigned long state;
@@ -454,6 +605,7 @@ void cca_pdev_stop_and_destroy(struct pci_dev *pdev)
return;
if (pf0_ep_dsc) {
+ kfree(pf0_ep_dsc->rmi_signature_algorithm);
kfree(pf0_ep_dsc->cert_chain.public_key);
kvfree(pf0_ep_dsc->cert_chain.cache);
kvfree(pf0_ep_dsc->vca);
diff --git a/drivers/virt/coco/arm-cca-host/rmi-da.h b/drivers/virt/coco/arm-cca-host/rmi-da.h
index f3bd106c8a54..92bcd9571cb8 100644
--- a/drivers/virt/coco/arm-cca-host/rmi-da.h
+++ b/drivers/virt/coco/arm-cca-host/rmi-da.h
@@ -59,6 +59,7 @@ struct cca_host_pdev_dsc {
* @pci: Physical Function 0 TDISP link context
* @pdev: pdev communication context
* @sel_stream: Selective IDE Stream descriptor
+ * @rmi_signature_algorithm: Signature algorithm used for public key
* @cert_chain: cetrificate chain
* @vca: SPDM's Version-Capabilities-Algorithms cache object
*/
@@ -67,6 +68,7 @@ struct cca_host_pf0_ep_dsc {
struct cca_host_pdev_dsc pdev;
struct pci_ide *sel_stream;
+ char *rmi_signature_algorithm;
struct {
struct cache_object *cache;
diff --git a/include/linux/arm-rmi-cmds.h b/include/linux/arm-rmi-cmds.h
index f947b2f4909a..1f1dc771a8ff 100644
--- a/include/linux/arm-rmi-cmds.h
+++ b/include/linux/arm-rmi-cmds.h
@@ -715,4 +715,13 @@ static inline unsigned long rmi_pdev_stop(unsigned long pdev_phys)
return res.a0;
}
+static inline unsigned long rmi_pdev_set_pubkey(unsigned long pdev_phys, unsigned long key_phys)
+{
+ struct arm_smccc_res res;
+
+ arm_smccc_1_1_invoke(SMC_RMI_PDEV_SET_PUBKEY, pdev_phys, key_phys, &res);
+
+ return res.a0;
+}
+
#endif
diff --git a/include/linux/arm-smccc-rmi.h b/include/linux/arm-smccc-rmi.h
index 3133b34354ce..fdc830379060 100644
--- a/include/linux/arm-smccc-rmi.h
+++ b/include/linux/arm-smccc-rmi.h
@@ -596,4 +596,22 @@ struct rmi_dev_comm_data {
};
};
+struct rmi_public_key_params {
+ union {
+ struct {
+ union { /* 0x0 */
+ u64 key_addr;
+ u8 padding0[0x400];
+ };
+ union { /* 0x400 */
+ u64 metadata_addr;
+ u8 padding1[0x400];
+ };
+ u64 key_len;
+ u64 metadata_len;
+ };
+ u8 padding[0x1000];
+ };
+};
+
#endif /* __LINUX_ARM_SMCCC_RMI_H_ */
--
2.43.0
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