diff options
Diffstat (limited to 'security/integrity/digsig.c')
| -rw-r--r-- | security/integrity/digsig.c | 225 |
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); +} |