[PATCH v8 04/30] hw/s390x/ipl: Create certificate store

[Zhuoying Cai <zycai@linux.ibm.com>]

Create a certificate store for boot certificates used for secure IPL.

Load certificates from the `boot-certs` parameter of s390-ccw-virtio
machine type option into the cert store.

Currently, only X.509 certificates in PEM format are supported, as the
QEMU command line accepts certificates in PEM format only.

Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
---
 docs/specs/s390x-secure-ipl.rst |  16 +++
 hw/s390x/cert-store.c           | 221 ++++++++++++++++++++++++++++++++
 hw/s390x/cert-store.h           |  41 ++++++
 hw/s390x/ipl.c                  |  10 ++
 hw/s390x/ipl.h                  |   3 +
 hw/s390x/meson.build            |   1 +
 include/hw/s390x/ipl/qipl.h     |   2 +
 7 files changed, 294 insertions(+)
 create mode 100644 docs/specs/s390x-secure-ipl.rst
 create mode 100644 hw/s390x/cert-store.c
 create mode 100644 hw/s390x/cert-store.h

diff --git a/docs/specs/s390x-secure-ipl.rst b/docs/specs/s390x-secure-ipl.rst
new file mode 100644
index 0000000000..7ddac98a37
--- /dev/null
+++ b/docs/specs/s390x-secure-ipl.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+s390 Certificate Store and Functions
+====================================
+
+s390 Certificate Store
+----------------------
+
+A certificate store is implemented for s390-ccw guests to retain within
+memory all certificates provided by the user via the command-line, which
+are expected to be stored somewhere on the host's file system. The store
+will keep track of the number of certificates, their respective size,
+and a summation of the sizes.
+
+Note: A maximum of 64 certificates are allowed to be stored in the certificate
+store.
diff --git a/hw/s390x/cert-store.c b/hw/s390x/cert-store.c
new file mode 100644
index 0000000000..f642d50795
--- /dev/null
+++ b/hw/s390x/cert-store.c
@@ -0,0 +1,221 @@
+/*
+ * S390 certificate store implementation
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Zhuoying Cai <zycai@linux.ibm.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "cert-store.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "qemu/option.h"
+#include "qemu/config-file.h"
+#include "hw/s390x/ebcdic.h"
+#include "hw/s390x/s390-virtio-ccw.h"
+#include "qemu/cutils.h"
+#include "crypto/x509-utils.h"
+#include "qapi/qapi-types-machine-s390x.h"
+
+static BootCertificatesList *s390_get_boot_certs(void)
+{
+    return S390_CCW_MACHINE(qdev_get_machine())->boot_certs;
+}
+
+static S390IPLCertificate *init_cert(char *path, Error **errp)
+{
+    int rc;
+    char *buf;
+    size_t size;
+    size_t der_len;
+    char name[CERT_NAME_MAX_LEN];
+    g_autofree gchar *filename = NULL;
+    S390IPLCertificate *cert = NULL;
+    g_autofree uint8_t *cert_der = NULL;
+    Error *local_err = NULL;
+
+    filename = g_path_get_basename(path);
+
+    if (!g_file_get_contents(path, &buf, &size, NULL)) {
+        error_setg(errp, "Failed to load certificate: %s", path);
+        return NULL;
+    }
+
+    rc = qcrypto_x509_convert_cert_der((uint8_t *)buf, size,
+                                       &cert_der, &der_len, &local_err);
+    if (rc != 0) {
+        error_propagate_prepend(errp, local_err,
+                                "Failed to initialize certificate: %s: ", path);
+        g_free(buf);
+        return NULL;
+    }
+
+    cert = g_new0(S390IPLCertificate, 1);
+    cert->size = size;
+    /*
+     * Store DER length only - reused for size calculation.
+     * cert_der is discarded because DER certificate data will be used once
+     * and can be regenerated from cert->raw.
+     */
+    cert->der_size = der_len;
+    /* store raw pointer - ownership transfers to cert */
+    cert->raw = (uint8_t *)buf;
+
+    /*
+     * Left justified certificate name with padding on the right with blanks.
+     * Convert certificate name to EBCDIC.
+     */
+    strpadcpy(name, CERT_NAME_MAX_LEN, filename, ' ');
+    ebcdic_put(cert->name, name, CERT_NAME_MAX_LEN);
+
+    return cert;
+}
+
+static void update_cert_store(S390IPLCertificateStore *cert_store,
+                              S390IPLCertificate *cert)
+{
+    size_t data_buf_size;
+    size_t keyid_buf_size;
+    size_t hash_buf_size;
+    size_t cert_buf_size;
+
+    /* length field is word aligned for later DIAG use */
+    keyid_buf_size = ROUND_UP(CERT_KEY_ID_LEN, 4);
+    hash_buf_size = ROUND_UP(CERT_HASH_LEN, 4);
+    cert_buf_size = ROUND_UP(cert->der_size, 4);
+    data_buf_size = keyid_buf_size + hash_buf_size + cert_buf_size;
+
+    if (cert_store->largest_cert_size < data_buf_size) {
+        cert_store->largest_cert_size = data_buf_size;
+    }
+
+    g_assert(cert_store->count < MAX_CERTIFICATES);
+
+    cert_store->certs[cert_store->count] = *cert;
+    cert_store->total_bytes += data_buf_size;
+    cert_store->count++;
+}
+
+static GPtrArray *get_cert_paths(Error **errp)
+{
+    struct stat st;
+    BootCertificatesList *path_list = NULL;
+    BootCertificatesList *list = NULL;
+    gchar *cert_path;
+    GDir *dir = NULL;
+    const gchar *filename;
+    bool is_empty;
+    g_autoptr(GError) err = NULL;
+    g_autoptr(GPtrArray) cert_path_builder = g_ptr_array_new_full(0, g_free);
+
+    path_list = s390_get_boot_certs();
+
+    for (list = path_list; list; list = list->next) {
+        cert_path = list->value->path;
+
+        if (g_strcmp0(cert_path, "") == 0) {
+            error_setg(errp, "Empty path in certificate path list is not allowed");
+            goto fail;
+        }
+
+        if (stat(cert_path, &st) != 0) {
+            error_setg(errp, "Failed to stat path '%s': %s",
+                       cert_path, g_strerror(errno));
+            goto fail;
+        }
+
+        if (S_ISREG(st.st_mode)) {
+            if (!g_str_has_suffix(cert_path, ".pem")) {
+                error_setg(errp, "Certificate file '%s' must have a .pem extension",
+                           cert_path);
+                goto fail;
+            }
+
+            g_ptr_array_add(cert_path_builder, g_strdup(cert_path));
+        } else if (S_ISDIR(st.st_mode)) {
+            dir = g_dir_open(cert_path, 0, &err);
+            if (dir == NULL) {
+                error_setg(errp, "Failed to open directory '%s': %s",
+                           cert_path, err->message);
+
+                goto fail;
+            }
+
+            is_empty = true;
+            while ((filename = g_dir_read_name(dir))) {
+                is_empty = false;
+
+                if (g_str_has_suffix(filename, ".pem")) {
+                    g_ptr_array_add(cert_path_builder,
+                                    g_build_filename(cert_path, filename, NULL));
+                } else {
+                    warn_report("skipping '%s': not a .pem file", filename);
+                }
+            }
+
+            if (is_empty) {
+                warn_report("'%s' directory is empty", cert_path);
+            }
+
+            g_dir_close(dir);
+        } else {
+            error_setg(errp, "Path '%s' is neither a file nor a directory", cert_path);
+            goto fail;
+        }
+    }
+
+    qapi_free_BootCertificatesList(path_list);
+    return g_steal_pointer(&cert_path_builder);
+
+fail:
+    qapi_free_BootCertificatesList(path_list);
+    return NULL;
+}
+
+void s390_ipl_create_cert_store(S390IPLCertificateStore *cert_store)
+{
+    GPtrArray *cert_path_builder;
+    Error *err = NULL;
+
+    /* If cert store is already populated, then no work to do */
+    if (cert_store->count) {
+        return;
+    }
+
+    cert_path_builder = get_cert_paths(&err);
+    if (cert_path_builder == NULL) {
+        error_report_err(err);
+        exit(1);
+    }
+
+    if (cert_path_builder->len == 0) {
+        g_ptr_array_free(cert_path_builder, TRUE);
+        return;
+    }
+
+    if (cert_path_builder->len > MAX_CERTIFICATES - 1) {
+        error_report("Cert store exceeds maximum of %d certificates", MAX_CERTIFICATES);
+        g_ptr_array_free(cert_path_builder, TRUE);
+        exit(1);
+    }
+
+    cert_store->largest_cert_size = 0;
+    cert_store->total_bytes = 0;
+
+    for (int i = 0; i < cert_path_builder->len; i++) {
+        g_autofree S390IPLCertificate *cert = init_cert(
+                                              (char *) cert_path_builder->pdata[i],
+                                              &err);
+        if (!cert) {
+            error_report_err(err);
+            g_ptr_array_free(cert_path_builder, TRUE);
+            exit(1);
+        }
+
+        update_cert_store(cert_store, cert);
+    }
+
+    g_ptr_array_free(cert_path_builder, TRUE);
+}
diff --git a/hw/s390x/cert-store.h b/hw/s390x/cert-store.h
new file mode 100644
index 0000000000..50e36e2389
--- /dev/null
+++ b/hw/s390x/cert-store.h
@@ -0,0 +1,41 @@
+/*
+ * S390 certificate store
+ *
+ * Copyright 2025 IBM Corp.
+ * Author(s): Zhuoying Cai <zycai@linux.ibm.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef HW_S390_CERT_STORE_H
+#define HW_S390_CERT_STORE_H
+
+#include "hw/s390x/ipl/qipl.h"
+#include "crypto/x509-utils.h"
+
+#define CERT_NAME_MAX_LEN  64
+
+#define CERT_KEY_ID_LEN    QCRYPTO_HASH_DIGEST_LEN_SHA256
+#define CERT_HASH_LEN      QCRYPTO_HASH_DIGEST_LEN_SHA256
+
+struct S390IPLCertificate {
+    uint8_t name[CERT_NAME_MAX_LEN];
+    size_t  size;
+    size_t  der_size;
+    uint8_t *raw;
+};
+typedef struct S390IPLCertificate S390IPLCertificate;
+
+struct S390IPLCertificateStore {
+    uint16_t count;
+    size_t   largest_cert_size;
+    size_t   total_bytes;
+    S390IPLCertificate certs[MAX_CERTIFICATES];
+};
+typedef struct S390IPLCertificateStore S390IPLCertificateStore;
+QEMU_BUILD_BUG_MSG(sizeof(S390IPLCertificateStore) != 5656,
+                   "size of S390IPLCertificateStore is wrong");
+
+void s390_ipl_create_cert_store(S390IPLCertificateStore *cert_store);
+
+#endif
diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index d34adb5522..ea108fe370 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -36,6 +36,7 @@
 #include "qemu/option.h"
 #include "qemu/ctype.h"
 #include "standard-headers/linux/virtio_ids.h"
+#include "cert-store.h"
 
 #define KERN_IMAGE_START                0x010000UL
 #define LINUX_MAGIC_ADDR                0x010008UL
@@ -425,6 +426,13 @@ void s390_ipl_convert_loadparm(char *ascii_lp, uint8_t *ebcdic_lp)
     }
 }
 
+S390IPLCertificateStore *s390_ipl_get_certificate_store(void)
+{
+    S390IPLState *ipl = get_ipl_device();
+
+    return &ipl->cert_store;
+}
+
 static bool s390_build_iplb(DeviceState *dev_st, IplParameterBlock *iplb)
 {
     CcwDevice *ccw_dev = NULL;
@@ -718,6 +726,8 @@ void s390_ipl_prepare_cpu(S390CPU *cpu)
     cpu->env.psw.addr = ipl->start_addr;
     cpu->env.psw.mask = IPL_PSW_MASK;
 
+    s390_ipl_create_cert_store(&ipl->cert_store);
+
     if (!ipl->kernel || ipl->iplb_valid) {
         cpu->env.psw.addr = ipl->bios_start_addr;
         if (!ipl->iplb_valid) {
diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
index 85be03de1b..0c773ac8ce 100644
--- a/hw/s390x/ipl.h
+++ b/hw/s390x/ipl.h
@@ -13,6 +13,7 @@
 #ifndef HW_S390_IPL_H
 #define HW_S390_IPL_H
 
+#include "cert-store.h"
 #include "cpu.h"
 #include "exec/target_page.h"
 #include "system/address-spaces.h"
@@ -35,6 +36,7 @@ int s390_ipl_pv_unpack(struct S390PVResponse *pv_resp);
 void s390_ipl_prepare_cpu(S390CPU *cpu);
 IplParameterBlock *s390_ipl_get_iplb(void);
 IplParameterBlock *s390_ipl_get_iplb_pv(void);
+S390IPLCertificateStore *s390_ipl_get_certificate_store(void);
 
 enum s390_reset {
     /* default is a reset not triggered by a CPU e.g. issued by QMP */
@@ -64,6 +66,7 @@ struct S390IPLState {
     IplParameterBlock iplb;
     IplParameterBlock iplb_pv;
     QemuIplParameters qipl;
+    S390IPLCertificateStore cert_store;
     uint64_t start_addr;
     uint64_t compat_start_addr;
     uint64_t bios_start_addr;
diff --git a/hw/s390x/meson.build b/hw/s390x/meson.build
index 8866012ddc..80d3d4a74d 100644
--- a/hw/s390x/meson.build
+++ b/hw/s390x/meson.build
@@ -17,6 +17,7 @@ s390x_ss.add(files(
   'sclpcpu.c',
   'sclpquiesce.c',
   'tod.c',
+  'cert-store.c',
 ))
 s390x_ss.add(when: 'CONFIG_KVM', if_true: files(
   'tod-kvm.c',
diff --git a/include/hw/s390x/ipl/qipl.h b/include/hw/s390x/ipl/qipl.h
index 6824391111..e505f44020 100644
--- a/include/hw/s390x/ipl/qipl.h
+++ b/include/hw/s390x/ipl/qipl.h
@@ -20,6 +20,8 @@
 #define LOADPARM_LEN    8
 #define NO_LOADPARM "\0\0\0\0\0\0\0\0"
 
+#define MAX_CERTIFICATES  64
+
 /*
  * The QEMU IPL Parameters will be stored at absolute address
  * 204 (0xcc) which means it is 32-bit word aligned but not
-- 
2.52.0