KEYS: validate certificate trust only with builtin keys
Instead of allowing public keys, with certificates signed by any
key on the system trusted keyring, to be added to a trusted keyring,
this patch further restricts the certificates to those signed only by
builtin keys on the system keyring.
This patch defines a new option 'builtin' for the kernel parameter
'keys_ownerid' to allow trust validation using builtin keys.
Simplified Mimi's "KEYS: define an owner trusted keyring" patch
Changelog v7:
- rename builtin_keys to use_builtin_keys
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bdb193a..90c12c5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -569,7 +569,7 @@
ca_keys= [KEYS] This parameter identifies a specific key(s) on
the system trusted keyring to be used for certificate
trust validation.
- format: id:<keyid>
+ format: { id:<keyid> | builtin }
ccw_timeout_log [S390]
See Documentation/s390/CommonIO for details.
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index d376195..927ce75 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -24,6 +24,7 @@
#include "public_key.h"
#include "x509_parser.h"
+static bool use_builtin_keys;
static char *ca_keyid;
#ifndef MODULE
@@ -34,6 +35,8 @@
if (strncmp(str, "id:", 3) == 0)
ca_keyid = str; /* owner key 'id:xxxxxx' */
+ else if (strcmp(str, "builtin") == 0)
+ use_builtin_keys = true;
return 1;
}
@@ -180,7 +183,6 @@
static int x509_validate_trust(struct x509_certificate *cert,
struct key *trust_keyring)
{
- const struct public_key *pk;
struct key *key;
int ret = 1;
@@ -195,8 +197,9 @@
cert->authority,
strlen(cert->authority));
if (!IS_ERR(key)) {
- pk = key->payload.data;
- ret = x509_check_signature(pk, cert);
+ if (!use_builtin_keys
+ || test_bit(KEY_FLAG_BUILTIN, &key->flags))
+ ret = x509_check_signature(key->payload.data, cert);
key_put(key);
}
return ret;
diff --git a/include/linux/key.h b/include/linux/key.h
index 017b082..65316f7 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -170,6 +170,7 @@
#define KEY_FLAG_INVALIDATED 7 /* set if key has been invalidated */
#define KEY_FLAG_TRUSTED 8 /* set if key is trusted */
#define KEY_FLAG_TRUSTED_ONLY 9 /* set if keyring only accepts links to trusted keys */
+#define KEY_FLAG_BUILTIN 10 /* set if key is builtin */
/* the key type and key description string
* - the desc is used to match a key against search criteria
diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c
index 52ebc70..875f64e 100644
--- a/kernel/system_keyring.c
+++ b/kernel/system_keyring.c
@@ -89,6 +89,7 @@
pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
PTR_ERR(key));
} else {
+ set_bit(KEY_FLAG_BUILTIN, &key_ref_to_ptr(key)->flags);
pr_notice("Loaded X.509 cert '%s'\n",
key_ref_to_ptr(key)->description);
key_ref_put(key);