Hi Varad, Thanks for your review! On Tue, Apr 13, 2021 at 04:28:11PM +0200, Varad Gautam wrote: > Hi, > > On 3/9/21 10:10 AM, 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) > > A bad cert might get here with vlen < 2, which would cause indexing into v to break. > Please add a check for vlen >= 2 before this. > I will add the check, thanks for your suggestion! > > + 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) > > Same here, for i == (vlen - 1), v[i + 1] would fetch outside of v. Or, does the > ASN.1 layout protect against this? > I will move the "(i + 10) > vlen" to the front of "v[i + 1] != 8". It can avoid that the last octet blob is less than 10 bytes. Thanks! Joey Lee > > + 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); > > + return 0; > > + } > > + > > return 0; > > } > > > > diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h > > index 47accec68cb0..1ccaebe2a28b 100644 > > --- a/include/crypto/public_key.h > > +++ b/include/crypto/public_key.h > > @@ -28,6 +28,7 @@ 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); > > > > -- > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5 > 90409 Nürnberg > Germany > > HRB 36809, AG Nürnberg > Geschäftsführer: Felix Imendörffer