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Message-Id: <20171230175804.7354-3-alonid@gmail.com>
Date: Sat, 30 Dec 2017 19:58:01 +0200
From: Dan Aloni <dan@...nelim.com>
To: linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Cc: Dan Aloni <dan@...nelim.com>
Subject: [PATCH 2/5] certs: allow in-kernel access of trusted keys
From: Dan Aloni <dan@...nelim.com>
Signed-off-by: Dan Aloni <dan@...nelim.com>
---
certs/system_keyring.c | 56 ++++++++++++++++++++++++++++++++++++++++++-
include/keys/system_keyring.h | 3 +++
2 files changed, 58 insertions(+), 1 deletion(-)
diff --git a/certs/system_keyring.c b/certs/system_keyring.c
index 6251d1b27f0c..ff7c18d8e67c 100644
--- a/certs/system_keyring.c
+++ b/certs/system_keyring.c
@@ -131,6 +131,8 @@ static __init int system_trusted_keyring_init(void)
*/
device_initcall(system_trusted_keyring_init);
+static char *first_asymmetric_key_description;
+
/*
* Load the compiled-in list of X.509 certificates.
*/
@@ -172,8 +174,11 @@ static __init int load_system_certificate_list(void)
pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
PTR_ERR(key));
} else {
+ first_asymmetric_key_description =
+ kstrdup(key_ref_to_ptr(key)->description,
+ GFP_KERNEL);
pr_notice("Loaded X.509 cert '%s'\n",
- key_ref_to_ptr(key)->description);
+ first_asymmetric_key_description);
key_ref_put(key);
}
p += plen;
@@ -265,3 +270,52 @@ int verify_pkcs7_signature(const void *data, size_t len,
EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
+
+/**
+ * get_first_asymmetric_key - Find a key by ID.
+ * @keyring: The keys to search.
+ *
+ * Return the first assymmetric key in a keyring.
+ */
+static struct key *get_first_asymmetric_key(struct key *keyring)
+{
+ key_ref_t ref;
+
+ ref = keyring_search(make_key_ref(keyring, 1),
+ &key_type_asymmetric,
+ first_asymmetric_key_description);
+ if (IS_ERR(ref)) {
+ switch (PTR_ERR(ref)) {
+ case -EACCES:
+ case -ENOTDIR:
+ case -EAGAIN:
+ return ERR_PTR(-ENOKEY);
+ default:
+ return ERR_CAST(ref);
+ }
+ }
+
+ return key_ref_to_ptr(ref);
+}
+
+/**
+ * find_asymmetric_key - Find a key by ID in the builtin trusted keys
+ * keyring, or return the first key in that keyring.
+ *
+ * @id_0: The first ID to look for or NULL.
+ * @id_1: The second ID to look for or NULL.
+ *
+ * The preferred identifier is the id_0 and the fallback identifier is
+ * the id_1. If both are given, the lookup is by the former, but the
+ * latter must also match. If none are given, the first key is returned.
+ */
+struct key *find_trusted_asymmetric_key(const struct asymmetric_key_id *id_0,
+ const struct asymmetric_key_id *id_1)
+{
+ struct key *keyring = builtin_trusted_keys;
+ if (!id_0 && !id_1) {
+ return get_first_asymmetric_key(keyring);
+ }
+
+ return find_asymmetric_key(keyring, id_0, id_1, false);
+}
diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
index 359c2f936004..0bef29eb8297 100644
--- a/include/keys/system_keyring.h
+++ b/include/keys/system_keyring.h
@@ -13,6 +13,7 @@
#define _KEYS_SYSTEM_KEYRING_H
#include <linux/key.h>
+#include <keys/asymmetric-type.h>
#ifdef CONFIG_SYSTEM_TRUSTED_KEYRING
@@ -61,5 +62,7 @@ static inline struct key *get_ima_blacklist_keyring(void)
}
#endif /* CONFIG_IMA_BLACKLIST_KEYRING */
+struct key *find_trusted_asymmetric_key(const struct asymmetric_key_id *id_0,
+ const struct asymmetric_key_id *id_1);
#endif /* _KEYS_SYSTEM_KEYRING_H */
--
2.13.6
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