[PATCH v3 07/10] KEYS: X.509: Flag Intermediate CA certs as endorsed

Eric Snowberg
2022-12-14T00:35:02Z

Currently X.509 intermediate certs with the CA flag set to false do not
have the endorsed CA (KEY_FLAG_ECA) set. Allow these intermediate certs to
be added. Requirements for an intermediate include: Usage extension
defined as keyCertSign, Basic Constrains for CA is false, and the
intermediate cert is signed by a current endorsed CA.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
---
crypto/asymmetric_keys/x509_public_key.c | 14 ++++++++++++--
include/linux/ima.h | 11 +++++++++++
include/linux/key-type.h | 1 +
security/keys/key.c | 5 +++++
4 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index fd1d7d6e68e7..75699987a6b1 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -208,8 +208,18 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
goto error_free_kids;
}

- if (cert->kcs_set && cert->root_ca)
- prep->payload_flags |= KEY_ALLOC_PECA;
+ if (cert->kcs_set) {
+ if (cert->root_ca)
+ prep->payload_flags |= KEY_ALLOC_PECA;
+ /*
+ * In this case it could be an Intermediate CA. Set
+ * KEY_MAYBE_PECA for now. If the restriction check
+ * passes later, the key will be allocated with the
+ * correct CA flag
+ */
+ else
+ prep->payload_flags |= KEY_MAYBE_PECA;
+ }

/* We're pinning the module by being linked against it */
__module_get(public_key_subtype.owner);
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 81708ca0ebc7..6597081b6b1a 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -12,6 +12,7 @@
#include <linux/security.h>
#include <linux/kexec.h>
#include <crypto/hash_info.h>
+#include <keys/system_keyring.h>
struct linux_binprm;

#ifdef CONFIG_IMA
@@ -181,6 +182,16 @@ static inline void ima_post_key_create_or_update(struct key *keyring,
bool create) {}
#endif /* CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS */

+#ifdef CONFIG_ASYMMETRIC_KEY_TYPE
+#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
+#define ima_validate_builtin_ca restrict_link_by_ca_builtin_and_secondary_trusted
+#else
+#define ima_validate_builtin_ca restrict_link_by_ca_builtin_trusted
+#endif
+#else
+#define ima_validate_builtin_ca restrict_link_reject
+#endif
+
#ifdef CONFIG_IMA_APPRAISE
extern bool is_ima_appraise_enabled(void);
extern void ima_inode_post_setattr(struct user_namespace *mnt_userns,
diff --git a/include/linux/key-type.h b/include/linux/key-type.h
index 0b500578441c..0d2f95f6b8a1 100644
--- a/include/linux/key-type.h
+++ b/include/linux/key-type.h
@@ -38,6 +38,7 @@ struct key_preparsed_payload {
time64_t expiry; /* Expiry time of key */
unsigned int payload_flags; /* Proposed payload flags */
#define KEY_ALLOC_PECA 0x0001 /* Proposed Endorsed CA (ECA) key */
+#define KEY_MAYBE_PECA 0x0002 /* Proposed possible ECA key */
} __randomize_layout;

typedef int (*request_key_actor_t)(struct key *auth_key, void *aux);
diff --git a/security/keys/key.c b/security/keys/key.c
index e6b4946aca70..69d5f143683f 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -900,6 +900,11 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
}
}

+ /* Previous restriction check passed therefore try to validate endorsed ca */
+ if ((prep.payload_flags & KEY_MAYBE_PECA) &&
+ !(ima_validate_builtin_ca(keyring, index_key.type, &prep.payload, NULL)))
+ prep.payload_flags |= KEY_ALLOC_PECA;
+
/* if we're going to allocate a new key, we're going to have
* to modify the keyring */
ret = key_permission(keyring_ref, KEY_NEED_WRITE);
--
2.27.0