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![Eric Snowberg](/assets/img/avatar_default.png)
Add machine keyring CA restriction options to control the type of keys that may be added to it. The motivation is separation of certificate signing from code signing keys. Subsquent work will limit certificates being loaded into the IMA keyring to code signing keys used for signature verification. When no restrictions are selected, all Machine Owner Keys (MOK) are added to the machine keyring. When CONFIG_INTEGRITY_CA_MACHINE_KEYRING is selected, the CA bit must be true. Also the key usage must contain keyCertSign, any other usage field may be set as well. When CONFIG_INTEGRITY_CA_MACHINE_KEYRING_MAX is selected, the CA bit must be true. Also the key usage must contain keyCertSign and the digitialSignature usage may not be set. Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com> Acked-by: Mimi Zohar <zohar@linux.ibm.com> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Tested-by: Mimi Zohar <zohar@linux.ibm.com> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
225 lines
5.3 KiB
C
225 lines
5.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2011 Intel Corporation
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*
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* Author:
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* Dmitry Kasatkin <dmitry.kasatkin@intel.com>
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*/
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/cred.h>
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#include <linux/kernel_read_file.h>
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#include <linux/key-type.h>
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#include <linux/digsig.h>
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#include <linux/vmalloc.h>
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#include <crypto/public_key.h>
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#include <keys/system_keyring.h>
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#include "integrity.h"
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static struct key *keyring[INTEGRITY_KEYRING_MAX];
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static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
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#ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
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"_evm",
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"_ima",
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#else
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".evm",
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".ima",
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#endif
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".platform",
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".machine",
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};
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#ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
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#define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
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#else
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#define restrict_link_to_ima restrict_link_by_builtin_trusted
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#endif
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static struct key *integrity_keyring_from_id(const unsigned int id)
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{
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if (id >= INTEGRITY_KEYRING_MAX)
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return ERR_PTR(-EINVAL);
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if (!keyring[id]) {
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keyring[id] =
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request_key(&key_type_keyring, keyring_name[id], NULL);
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if (IS_ERR(keyring[id])) {
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int err = PTR_ERR(keyring[id]);
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pr_err("no %s keyring: %d\n", keyring_name[id], err);
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keyring[id] = NULL;
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return ERR_PTR(err);
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}
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}
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return keyring[id];
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}
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int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
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const char *digest, int digestlen)
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{
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struct key *keyring;
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if (siglen < 2)
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return -EINVAL;
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keyring = integrity_keyring_from_id(id);
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if (IS_ERR(keyring))
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return PTR_ERR(keyring);
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switch (sig[1]) {
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case 1:
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/* v1 API expect signature without xattr type */
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return digsig_verify(keyring, sig + 1, siglen - 1, digest,
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digestlen);
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case 2: /* regular file data hash based signature */
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case 3: /* struct ima_file_id data based signature */
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return asymmetric_verify(keyring, sig, siglen, digest,
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digestlen);
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}
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return -EOPNOTSUPP;
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}
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int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig)
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{
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struct key *keyring;
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keyring = integrity_keyring_from_id(id);
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if (IS_ERR(keyring))
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return PTR_ERR(keyring);
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return ima_modsig_verify(keyring, modsig);
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}
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static int __init __integrity_init_keyring(const unsigned int id,
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key_perm_t perm,
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struct key_restriction *restriction)
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{
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const struct cred *cred = current_cred();
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int err = 0;
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keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
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KGIDT_INIT(0), cred, perm,
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KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
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if (IS_ERR(keyring[id])) {
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err = PTR_ERR(keyring[id]);
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pr_info("Can't allocate %s keyring (%d)\n",
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keyring_name[id], err);
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keyring[id] = NULL;
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} else {
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if (id == INTEGRITY_KEYRING_PLATFORM)
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set_platform_trusted_keys(keyring[id]);
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if (id == INTEGRITY_KEYRING_MACHINE && trust_moklist())
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set_machine_trusted_keys(keyring[id]);
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if (id == INTEGRITY_KEYRING_IMA)
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load_module_cert(keyring[id]);
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}
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return err;
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}
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int __init integrity_init_keyring(const unsigned int id)
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{
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struct key_restriction *restriction;
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key_perm_t perm;
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int ret;
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perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
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| KEY_USR_READ | KEY_USR_SEARCH;
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if (id == INTEGRITY_KEYRING_PLATFORM ||
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(id == INTEGRITY_KEYRING_MACHINE &&
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!IS_ENABLED(CONFIG_INTEGRITY_CA_MACHINE_KEYRING))) {
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restriction = NULL;
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goto out;
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}
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if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
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return 0;
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restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
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if (!restriction)
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return -ENOMEM;
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if (id == INTEGRITY_KEYRING_MACHINE)
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restriction->check = restrict_link_by_ca;
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else
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restriction->check = restrict_link_to_ima;
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/*
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* MOK keys can only be added through a read-only runtime services
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* UEFI variable during boot. No additional keys shall be allowed to
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* load into the machine keyring following init from userspace.
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*/
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if (id != INTEGRITY_KEYRING_MACHINE)
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perm |= KEY_USR_WRITE;
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out:
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ret = __integrity_init_keyring(id, perm, restriction);
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if (ret)
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kfree(restriction);
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return ret;
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}
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static int __init integrity_add_key(const unsigned int id, const void *data,
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off_t size, key_perm_t perm)
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{
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key_ref_t key;
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int rc = 0;
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if (!keyring[id])
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return -EINVAL;
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key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
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NULL, data, size, perm,
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KEY_ALLOC_NOT_IN_QUOTA);
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if (IS_ERR(key)) {
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rc = PTR_ERR(key);
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pr_err("Problem loading X.509 certificate %d\n", rc);
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} else {
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pr_notice("Loaded X.509 cert '%s'\n",
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key_ref_to_ptr(key)->description);
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key_ref_put(key);
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}
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return rc;
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}
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int __init integrity_load_x509(const unsigned int id, const char *path)
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{
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void *data = NULL;
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size_t size;
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int rc;
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key_perm_t perm;
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rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL,
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READING_X509_CERTIFICATE);
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if (rc < 0) {
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pr_err("Unable to open file: %s (%d)", path, rc);
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return rc;
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}
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size = rc;
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perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
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pr_info("Loading X.509 certificate: %s\n", path);
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rc = integrity_add_key(id, (const void *)data, size, perm);
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vfree(data);
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return rc;
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}
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int __init integrity_load_cert(const unsigned int id, const char *source,
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const void *data, size_t len, key_perm_t perm)
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{
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if (!data)
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return -EINVAL;
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pr_info("Loading X.509 certificate: %s\n", source);
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return integrity_add_key(id, data, len, perm);
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}
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