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-rw-r--r--certs/system_keyring.c277
1 files changed, 277 insertions, 0 deletions
diff --git a/certs/system_keyring.c b/certs/system_keyring.c
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+++ b/certs/system_keyring.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/* System trusted keyring for trusted public keys
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/verification.h>
+#include <keys/asymmetric-type.h>
+#include <keys/system_keyring.h>
+#include <crypto/pkcs7.h>
+#include "common.h"
+
+static struct key *builtin_trusted_keys;
+#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
+static struct key *secondary_trusted_keys;
+#endif
+#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
+static struct key *platform_trusted_keys;
+#endif
+
+extern __initconst const u8 system_certificate_list[];
+extern __initconst const unsigned long system_certificate_list_size;
+
+/**
+ * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
+ *
+ * Restrict the addition of keys into a keyring based on the key-to-be-added
+ * being vouched for by a key in the built in system keyring.
+ */
+int restrict_link_by_builtin_trusted(struct key *dest_keyring,
+ const struct key_type *type,
+ const union key_payload *payload,
+ struct key *restriction_key)
+{
+ return restrict_link_by_signature(dest_keyring, type, payload,
+ builtin_trusted_keys);
+}
+
+#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
+/**
+ * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
+ * addition by both builtin and secondary keyrings
+ *
+ * Restrict the addition of keys into a keyring based on the key-to-be-added
+ * being vouched for by a key in either the built-in or the secondary system
+ * keyrings.
+ */
+int restrict_link_by_builtin_and_secondary_trusted(
+ struct key *dest_keyring,
+ const struct key_type *type,
+ const union key_payload *payload,
+ struct key *restrict_key)
+{
+ /* If we have a secondary trusted keyring, then that contains a link
+ * through to the builtin keyring and the search will follow that link.
+ */
+ if (type == &key_type_keyring &&
+ dest_keyring == secondary_trusted_keys &&
+ payload == &builtin_trusted_keys->payload)
+ /* Allow the builtin keyring to be added to the secondary */
+ return 0;
+
+ return restrict_link_by_signature(dest_keyring, type, payload,
+ secondary_trusted_keys);
+}
+
+/**
+ * Allocate a struct key_restriction for the "builtin and secondary trust"
+ * keyring. Only for use in system_trusted_keyring_init().
+ */
+static __init struct key_restriction *get_builtin_and_secondary_restriction(void)
+{
+ struct key_restriction *restriction;
+
+ restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
+
+ if (!restriction)
+ panic("Can't allocate secondary trusted keyring restriction\n");
+
+ restriction->check = restrict_link_by_builtin_and_secondary_trusted;
+
+ return restriction;
+}
+#endif
+
+/*
+ * Create the trusted keyrings
+ */
+static __init int system_trusted_keyring_init(void)
+{
+ pr_notice("Initialise system trusted keyrings\n");
+
+ builtin_trusted_keys =
+ keyring_alloc(".builtin_trusted_keys",
+ KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
+ KEY_ALLOC_NOT_IN_QUOTA,
+ NULL, NULL);
+ if (IS_ERR(builtin_trusted_keys))
+ panic("Can't allocate builtin trusted keyring\n");
+
+#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
+ secondary_trusted_keys =
+ keyring_alloc(".secondary_trusted_keys",
+ KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
+ ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH |
+ KEY_USR_WRITE),
+ KEY_ALLOC_NOT_IN_QUOTA,
+ get_builtin_and_secondary_restriction(),
+ NULL);
+ if (IS_ERR(secondary_trusted_keys))
+ panic("Can't allocate secondary trusted keyring\n");
+
+ if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
+ panic("Can't link trusted keyrings\n");
+#endif
+
+ return 0;
+}
+
+/*
+ * Must be initialised before we try and load the keys into the keyring.
+ */
+device_initcall(system_trusted_keyring_init);
+
+/*
+ * Load the compiled-in list of X.509 certificates.
+ */
+static __init int load_system_certificate_list(void)
+{
+ pr_notice("Loading compiled-in X.509 certificates\n");
+
+ return load_certificate_list(system_certificate_list, system_certificate_list_size,
+ builtin_trusted_keys);
+}
+late_initcall(load_system_certificate_list);
+
+#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
+
+/**
+ * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data.
+ * @data: The data to be verified (NULL if expecting internal data).
+ * @len: Size of @data.
+ * @pkcs7: The PKCS#7 message that is the signature.
+ * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
+ * (void *)1UL for all trusted keys).
+ * @usage: The use to which the key is being put.
+ * @view_content: Callback to gain access to content.
+ * @ctx: Context for callback.
+ */
+int verify_pkcs7_message_sig(const void *data, size_t len,
+ struct pkcs7_message *pkcs7,
+ struct key *trusted_keys,
+ enum key_being_used_for usage,
+ int (*view_content)(void *ctx,
+ const void *data, size_t len,
+ size_t asn1hdrlen),
+ void *ctx)
+{
+ int ret;
+
+ /* The data should be detached - so we need to supply it. */
+ if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
+ pr_err("PKCS#7 signature with non-detached data\n");
+ ret = -EBADMSG;
+ goto error;
+ }
+
+ ret = pkcs7_verify(pkcs7, usage);
+ if (ret < 0)
+ goto error;
+
+ if (!trusted_keys) {
+ trusted_keys = builtin_trusted_keys;
+ } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) {
+#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
+ trusted_keys = secondary_trusted_keys;
+#else
+ trusted_keys = builtin_trusted_keys;
+#endif
+ } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) {
+#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
+ trusted_keys = platform_trusted_keys;
+#else
+ trusted_keys = NULL;
+#endif
+ if (!trusted_keys) {
+ ret = -ENOKEY;
+ pr_devel("PKCS#7 platform keyring is not available\n");
+ goto error;
+ }
+
+ ret = is_key_on_revocation_list(pkcs7);
+ if (ret != -ENOKEY) {
+ pr_devel("PKCS#7 platform key is on revocation list\n");
+ goto error;
+ }
+ }
+ ret = pkcs7_validate_trust(pkcs7, trusted_keys);
+ if (ret < 0) {
+ if (ret == -ENOKEY)
+ pr_devel("PKCS#7 signature not signed with a trusted key\n");
+ goto error;
+ }
+
+ if (view_content) {
+ size_t asn1hdrlen;
+
+ ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
+ if (ret < 0) {
+ if (ret == -ENODATA)
+ pr_devel("PKCS#7 message does not contain data\n");
+ goto error;
+ }
+
+ ret = view_content(ctx, data, len, asn1hdrlen);
+ }
+
+error:
+ pr_devel("<==%s() = %d\n", __func__, ret);
+ return ret;
+}
+
+/**
+ * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.
+ * @data: The data to be verified (NULL if expecting internal data).
+ * @len: Size of @data.
+ * @raw_pkcs7: The PKCS#7 message that is the signature.
+ * @pkcs7_len: The size of @raw_pkcs7.
+ * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
+ * (void *)1UL for all trusted keys).
+ * @usage: The use to which the key is being put.
+ * @view_content: Callback to gain access to content.
+ * @ctx: Context for callback.
+ */
+int verify_pkcs7_signature(const void *data, size_t len,
+ const void *raw_pkcs7, size_t pkcs7_len,
+ struct key *trusted_keys,
+ enum key_being_used_for usage,
+ int (*view_content)(void *ctx,
+ const void *data, size_t len,
+ size_t asn1hdrlen),
+ void *ctx)
+{
+ struct pkcs7_message *pkcs7;
+ int ret;
+
+ pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
+ if (IS_ERR(pkcs7))
+ return PTR_ERR(pkcs7);
+
+ ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage,
+ view_content, ctx);
+
+ pkcs7_free_message(pkcs7);
+ pr_devel("<==%s() = %d\n", __func__, ret);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
+
+#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
+
+#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
+void __init set_platform_trusted_keys(struct key *keyring)
+{
+ platform_trusted_keys = keyring;
+}
+#endif
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