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authorMat Martineau <mathew.j.martineau@linux.intel.com>2016-05-06 14:25:39 -0700
committerMat Martineau <mathew.j.martineau@linux.intel.com>2017-04-04 14:10:12 -0700
commit97d3aa0f313435a24440e7157c9c9115c58ca463 (patch)
tree56c00ecd720a6b1f9564ec01f5e6a3d8b805c455
parent6563c91fd645556c7801748f15bc727c77fcd311 (diff)
KEYS: Add a lookup_restriction function for the asymmetric key type
Look up asymmetric keyring restriction information using the key-type lookup_restrict hook. Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
-rw-r--r--Documentation/crypto/asymmetric-keys.txt35
-rw-r--r--crypto/asymmetric_keys/asymmetric_type.c52
2 files changed, 79 insertions, 8 deletions
diff --git a/Documentation/crypto/asymmetric-keys.txt b/Documentation/crypto/asymmetric-keys.txt
index 2b7816dea370..4373e7d86c6a 100644
--- a/Documentation/crypto/asymmetric-keys.txt
+++ b/Documentation/crypto/asymmetric-keys.txt
@@ -311,3 +311,38 @@ Functions are provided to register and unregister parsers:
Parsers may not have the same name. The names are otherwise only used for
displaying in debugging messages.
+
+
+=========================
+KEYRING LINK RESTRICTIONS
+=========================
+
+Keyrings created from userspace using add_key can be configured to check the
+signature of the key being linked.
+
+Several restriction methods are available:
+
+ (1) Restrict using the kernel builtin trusted keyring
+
+ - Option string used with KEYCTL_RESTRICT_KEYRING:
+ - "builtin_trusted"
+
+ The kernel builtin trusted keyring will be searched for the signing
+ key. The ca_keys kernel parameter also affects which keys are used for
+ signature verification.
+
+ (2) Restrict using the kernel builtin and secondary trusted keyrings
+
+ - Option string used with KEYCTL_RESTRICT_KEYRING:
+ - "builtin_and_secondary_trusted"
+
+ The kernel builtin and secondary trusted keyrings will be searched for the
+ signing key. The ca_keys kernel parameter also affects which keys are used
+ for signature verification.
+
+In all of these cases, if the signing key is found the signature of the key to
+be linked will be verified using the signing key. The requested key is added
+to the keyring only if the signature is successfully verified. -ENOKEY is
+returned if the parent certificate could not be found, or -EKEYREJECTED is
+returned if the signature check fails or the key is blacklisted. Other errors
+may be returned if the signature check could not be performed.
diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index 6600181d5d01..2e3380d09631 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -17,6 +17,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ctype.h>
+#include <keys/system_keyring.h>
#include "asymmetric_keys.h"
MODULE_LICENSE("GPL");
@@ -451,15 +452,50 @@ static void asymmetric_key_destroy(struct key *key)
asymmetric_key_free_kids(kids);
}
+static struct key_restriction *asymmetric_restriction_alloc(
+ key_restrict_link_func_t check,
+ struct key *key)
+{
+ struct key_restriction *keyres =
+ kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
+
+ if (!keyres)
+ return ERR_PTR(-ENOMEM);
+
+ keyres->check = check;
+ keyres->key = key;
+ keyres->keytype = &key_type_asymmetric;
+
+ return keyres;
+}
+
+/*
+ * look up keyring restrict functions for asymmetric keys
+ */
+static struct key_restriction *asymmetric_lookup_restriction(
+ const char *restriction)
+{
+ if (strcmp("builtin_trusted", restriction) == 0)
+ return asymmetric_restriction_alloc(
+ restrict_link_by_builtin_trusted, NULL);
+
+ if (strcmp("builtin_and_secondary_trusted", restriction) == 0)
+ return asymmetric_restriction_alloc(
+ restrict_link_by_builtin_and_secondary_trusted, NULL);
+
+ return ERR_PTR(-EINVAL);
+}
+
struct key_type key_type_asymmetric = {
- .name = "asymmetric",
- .preparse = asymmetric_key_preparse,
- .free_preparse = asymmetric_key_free_preparse,
- .instantiate = generic_key_instantiate,
- .match_preparse = asymmetric_key_match_preparse,
- .match_free = asymmetric_key_match_free,
- .destroy = asymmetric_key_destroy,
- .describe = asymmetric_key_describe,
+ .name = "asymmetric",
+ .preparse = asymmetric_key_preparse,
+ .free_preparse = asymmetric_key_free_preparse,
+ .instantiate = generic_key_instantiate,
+ .match_preparse = asymmetric_key_match_preparse,
+ .match_free = asymmetric_key_match_free,
+ .destroy = asymmetric_key_destroy,
+ .describe = asymmetric_key_describe,
+ .lookup_restriction = asymmetric_lookup_restriction,
};
EXPORT_SYMBOL_GPL(key_type_asymmetric);