[PATCH v4 4/6] KEYS: X.509: Parse Key Usage
flat view
STALE1338d
SUPERSEDED
From: Eric Snowberg <eric.snowberg@oracle.com>
Date: 2023-02-07 03:01:26
Also in:
keyrings, linux-crypto, linux-integrity, lkml
Subsystem:
asymmetric keys, crypto api, the rest · Maintainers:
David Howells, Lukas Wunner, Ignat Korchagin, Herbert Xu, "David S. Miller", Linus Torvalds
Revision v4 of 6 in this series.
Revisions (6)
Parse the X.509 Key Usage. The key usage extension defines the purpose of
the key contained in the certificate.
id-ce-keyUsage OBJECT IDENTIFIER ::= { id-ce 15 }
KeyUsage ::= BIT STRING {
digitalSignature (0),
contentCommitment (1),
keyEncipherment (2),
dataEncipherment (3),
keyAgreement (4),
keyCertSign (5),
cRLSign (6),
encipherOnly (7),
decipherOnly (8) }
If the keyCertSign or digitalSignature is set, store it in the
public_key structure. This will be used in a follow on patch that
requires knowing the certificate key usage type.
Link: https://www.rfc-editor.org/rfc/rfc5280#section-4.2.1.3
Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
---
crypto/asymmetric_keys/x509_cert_parser.c | 28 +++++++++++++++++++++++
include/crypto/public_key.h | 2 ++
2 files changed, 30 insertions(+)
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 77547d4bd94d..0a7049b470c1 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c@@ -579,6 +579,34 @@ int x509_process_extension(void *context, size_t hdrlen, return 0; } + if (ctx->last_oid == OID_keyUsage) { + /* + * Get hold of the keyUsage bit string + * v[1] is the encoding size + * (Expect either 0x02 or 0x03, making it 1 or 2 bytes) + * v[2] is the number of unused bits in the bit string + * (If >= 3 keyCertSign is missing when v[1] = 0x02) + * v[3] and possibly v[4] contain the bit string + * + * From RFC 5280 4.2.1.3: + * 0x04 is where keyCertSign lands in this bit string + * 0x80 is where digitalSignature lands in this bit string + */ + if (v[0] != ASN1_BTS) + return -EBADMSG; + if (vlen < 4) + return -EBADMSG; + if (v[2] >= 8) + return -EBADMSG; + if (v[3] & 0x80) + ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_DIGITALSIG; + if (v[1] == 0x02 && v[2] <= 2 && (v[3] & 0x04)) + ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN; + else if (vlen > 4 && v[1] == 0x03 && (v[3] & 0x04)) + ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN; + return 0; + } + if (ctx->last_oid == OID_authorityKeyIdentifier) { /* Get hold of the CA key fingerprint */ ctx->raw_akid = v;
diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index c401762850f2..03c3fb990d59 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h@@ -30,6 +30,8 @@ struct public_key { const char *pkey_algo; unsigned long key_eflags; /* key extension flags */ #define KEY_EFLAG_CA 0 /* set if the CA basic constraints is set */ +#define KEY_EFLAG_DIGITALSIG 1 /* set if the digitalSignature usage is set */ +#define KEY_EFLAG_KEYCERTSIGN 2 /* set if the keyCertSign usage is set */ }; extern void public_key_free(struct public_key *key);
--
2.27.0