On Wed, Jan 20, 2021 at 05:05:14PM +0800, Lee, Chun-Yi wrote: > This patch adds the logic for parsing the CodeSign extended key usage > extension in X.509. The parsing result will be set to the eku flag > which is carried by public key. It can be used in the PKCS#7 > verification. > > Signed-off-by: "Lee, Chun-Yi" <jlee@xxxxxxxx> > --- > crypto/asymmetric_keys/x509_cert_parser.c | 24 ++++++++++++++++++++++++ > include/crypto/public_key.h | 1 + > include/linux/oid_registry.h | 5 +++++ > 3 files changed, 30 insertions(+) > > diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c > index 52c9b455fc7d..65721313b265 100644 > --- a/crypto/asymmetric_keys/x509_cert_parser.c > +++ b/crypto/asymmetric_keys/x509_cert_parser.c > @@ -497,6 +497,8 @@ int x509_process_extension(void *context, size_t hdrlen, > struct x509_parse_context *ctx = context; > struct asymmetric_key_id *kid; > const unsigned char *v = value; > + int i = 0; > + enum OID oid; > > pr_debug("Extension: %u\n", ctx->last_oid); > > @@ -526,6 +528,28 @@ int x509_process_extension(void *context, size_t hdrlen, > return 0; > } > > + if (ctx->last_oid == OID_extKeyUsage) { > + if (v[0] != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ) || > + v[1] != vlen - 2) > + return -EBADMSG; > + i += 2; > + > + while (i < vlen) { > + /* A 10 bytes EKU OID Octet blob = > + * ASN1_OID + size byte + 8 bytes OID */ > + if (v[i] != ASN1_OID || v[i + 1] != 8 || (i + 10) > vlen) > + return -EBADMSG; > + > + oid = look_up_OID(v + i + 2, v[i + 1]); > + if (oid == OID_codeSigning) { > + ctx->cert->pub->eku |= EKU_codeSigning; > + } > + i += 10; > + } > + pr_debug("extKeyUsage: %d\n", ctx->cert->pub->eku); With eBPF around, does this make any sense? /Jarkko > + return 0; > + } > + > return 0; > } > > diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h > index 948c5203ca9c..07a1b28460a2 100644 > --- a/include/crypto/public_key.h > +++ b/include/crypto/public_key.h > @@ -29,6 +29,7 @@ struct public_key { > bool key_is_private; > const char *id_type; > const char *pkey_algo; > + unsigned int eku : 9; /* Extended Key Usage (9-bit) */ > }; > > extern void public_key_free(struct public_key *key); > diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h > index 4462ed2c18cd..e20e8eb53b21 100644 > --- a/include/linux/oid_registry.h > +++ b/include/linux/oid_registry.h > @@ -113,9 +113,14 @@ enum OID { > OID_SM2_with_SM3, /* 1.2.156.10197.1.501 */ > OID_sm3WithRSAEncryption, /* 1.2.156.10197.1.504 */ > > + /* Extended key purpose OIDs [RFC 5280] */ > + OID_codeSigning, /* 1.3.6.1.5.5.7.3.3 */ > + > OID__NR > }; > > +#define EKU_codeSigning (1 << 2) > + > extern enum OID look_up_OID(const void *data, size_t datasize); > extern int sprint_oid(const void *, size_t, char *, size_t); > extern int sprint_OID(enum OID, char *, size_t); > -- > 2.16.4 > >