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-rw-r--r--security/integrity/digsig.c225
1 files changed, 225 insertions, 0 deletions
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
new file mode 100644
index 0000000000..df387de29b
--- /dev/null
+++ b/security/integrity/digsig.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 Intel Corporation
+ *
+ * Author:
+ * Dmitry Kasatkin <dmitry.kasatkin@intel.com>
+ */
+
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/kernel_read_file.h>
+#include <linux/key-type.h>
+#include <linux/digsig.h>
+#include <linux/vmalloc.h>
+#include <crypto/public_key.h>
+#include <keys/system_keyring.h>
+
+#include "integrity.h"
+
+static struct key *keyring[INTEGRITY_KEYRING_MAX];
+
+static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
+#ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
+ "_evm",
+ "_ima",
+#else
+ ".evm",
+ ".ima",
+#endif
+ ".platform",
+ ".machine",
+};
+
+#ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
+#define restrict_link_to_ima restrict_link_by_digsig_builtin_and_secondary
+#else
+#define restrict_link_to_ima restrict_link_by_digsig_builtin
+#endif
+
+static struct key *integrity_keyring_from_id(const unsigned int id)
+{
+ if (id >= INTEGRITY_KEYRING_MAX)
+ return ERR_PTR(-EINVAL);
+
+ if (!keyring[id]) {
+ keyring[id] =
+ request_key(&key_type_keyring, keyring_name[id], NULL);
+ if (IS_ERR(keyring[id])) {
+ int err = PTR_ERR(keyring[id]);
+ pr_err("no %s keyring: %d\n", keyring_name[id], err);
+ keyring[id] = NULL;
+ return ERR_PTR(err);
+ }
+ }
+
+ return keyring[id];
+}
+
+int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
+ const char *digest, int digestlen)
+{
+ struct key *keyring;
+
+ if (siglen < 2)
+ return -EINVAL;
+
+ keyring = integrity_keyring_from_id(id);
+ if (IS_ERR(keyring))
+ return PTR_ERR(keyring);
+
+ switch (sig[1]) {
+ case 1:
+ /* v1 API expect signature without xattr type */
+ return digsig_verify(keyring, sig + 1, siglen - 1, digest,
+ digestlen);
+ case 2: /* regular file data hash based signature */
+ case 3: /* struct ima_file_id data based signature */
+ return asymmetric_verify(keyring, sig, siglen, digest,
+ digestlen);
+ }
+
+ return -EOPNOTSUPP;
+}
+
+int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig)
+{
+ struct key *keyring;
+
+ keyring = integrity_keyring_from_id(id);
+ if (IS_ERR(keyring))
+ return PTR_ERR(keyring);
+
+ return ima_modsig_verify(keyring, modsig);
+}
+
+static int __init __integrity_init_keyring(const unsigned int id,
+ key_perm_t perm,
+ struct key_restriction *restriction)
+{
+ const struct cred *cred = current_cred();
+ int err = 0;
+
+ keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
+ KGIDT_INIT(0), cred, perm,
+ KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
+ if (IS_ERR(keyring[id])) {
+ err = PTR_ERR(keyring[id]);
+ pr_info("Can't allocate %s keyring (%d)\n",
+ keyring_name[id], err);
+ keyring[id] = NULL;
+ } else {
+ if (id == INTEGRITY_KEYRING_PLATFORM)
+ set_platform_trusted_keys(keyring[id]);
+ if (id == INTEGRITY_KEYRING_MACHINE && imputed_trust_enabled())
+ set_machine_trusted_keys(keyring[id]);
+ if (id == INTEGRITY_KEYRING_IMA)
+ load_module_cert(keyring[id]);
+ }
+
+ return err;
+}
+
+int __init integrity_init_keyring(const unsigned int id)
+{
+ struct key_restriction *restriction;
+ key_perm_t perm;
+ int ret;
+
+ perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
+ | KEY_USR_READ | KEY_USR_SEARCH;
+
+ if (id == INTEGRITY_KEYRING_PLATFORM ||
+ (id == INTEGRITY_KEYRING_MACHINE &&
+ !IS_ENABLED(CONFIG_INTEGRITY_CA_MACHINE_KEYRING))) {
+ restriction = NULL;
+ goto out;
+ }
+
+ if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
+ return 0;
+
+ restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
+ if (!restriction)
+ return -ENOMEM;
+
+ if (id == INTEGRITY_KEYRING_MACHINE)
+ restriction->check = restrict_link_by_ca;
+ else
+ restriction->check = restrict_link_to_ima;
+
+ /*
+ * MOK keys can only be added through a read-only runtime services
+ * UEFI variable during boot. No additional keys shall be allowed to
+ * load into the machine keyring following init from userspace.
+ */
+ if (id != INTEGRITY_KEYRING_MACHINE)
+ perm |= KEY_USR_WRITE;
+
+out:
+ ret = __integrity_init_keyring(id, perm, restriction);
+ if (ret)
+ kfree(restriction);
+ return ret;
+}
+
+static int __init integrity_add_key(const unsigned int id, const void *data,
+ off_t size, key_perm_t perm)
+{
+ key_ref_t key;
+ int rc = 0;
+
+ if (!keyring[id])
+ return -EINVAL;
+
+ key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
+ NULL, data, size, perm,
+ KEY_ALLOC_NOT_IN_QUOTA);
+ if (IS_ERR(key)) {
+ rc = PTR_ERR(key);
+ pr_err("Problem loading X.509 certificate %d\n", rc);
+ } else {
+ pr_notice("Loaded X.509 cert '%s'\n",
+ key_ref_to_ptr(key)->description);
+ key_ref_put(key);
+ }
+
+ return rc;
+
+}
+
+int __init integrity_load_x509(const unsigned int id, const char *path)
+{
+ void *data = NULL;
+ size_t size;
+ int rc;
+ key_perm_t perm;
+
+ rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL,
+ READING_X509_CERTIFICATE);
+ if (rc < 0) {
+ pr_err("Unable to open file: %s (%d)", path, rc);
+ return rc;
+ }
+ size = rc;
+
+ perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
+
+ pr_info("Loading X.509 certificate: %s\n", path);
+ rc = integrity_add_key(id, (const void *)data, size, perm);
+
+ vfree(data);
+ return rc;
+}
+
+int __init integrity_load_cert(const unsigned int id, const char *source,
+ const void *data, size_t len, key_perm_t perm)
+{
+ if (!data)
+ return -EINVAL;
+
+ pr_info("Loading X.509 certificate: %s\n", source);
+ return integrity_add_key(id, data, len, perm);
+}