From: joeyli <jlee@suse.com>
To: Varad Gautam <varad.gautam@suse.com>
Cc: "Lee, Chun-Yi" <joeyli.kernel@gmail.com>,
David Howells <dhowells@redhat.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S . Miller" <davem@davemloft.net>,
Ben Boeckel <me@benboeckel.net>,
Randy Dunlap <rdunlap@infradead.org>,
Malte Gell <malte.gell@gmx.de>,
keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] X.509: Add CodeSigning extended key usage parsing
Date: Thu, 15 Apr 2021 00:01:15 +0800 [thread overview]
Message-ID: <20210414160115.GC25844@linux-l9pv.suse> (raw)
In-Reply-To: <5eb3e055-8e41-80b5-8caf-c80bbf2f4068@suse.com>
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@suse.com>
> > ---
> > 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);
> >
>
> --
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> Maxfeldstr. 5
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next prev parent reply other threads:[~2021-04-14 16:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 9:10 [PATCH v5 0/4] Check codeSigning extended key usage extension Lee, Chun-Yi
2021-03-09 9:10 ` [PATCH 1/4] X.509: Add CodeSigning extended key usage parsing Lee, Chun-Yi
2021-04-13 14:28 ` Varad Gautam
2021-04-14 16:01 ` joeyli [this message]
2021-03-09 9:10 ` [PATCH 2/4] PKCS#7: Check codeSigning EKU for kernel module and kexec pe verification Lee, Chun-Yi
2021-03-09 9:10 ` [PATCH 3/4] modsign: Add codeSigning EKU when generating X.509 key generation config Lee, Chun-Yi
2021-03-09 9:10 ` [PATCH 4/4] Documentation/admin-guide/module-signing.rst: add openssl command option example for CodeSign EKU Lee, Chun-Yi
-- strict thread matches above, loose matches on Subject: below --
2021-04-09 2:46 [PATCH v5 0/4] Check codeSigning extended key usage extension Lee, Chun-Yi
2021-04-09 2:46 ` [PATCH 1/4] X.509: Add CodeSigning extended key usage parsing Lee, Chun-Yi
2021-03-23 3:55 [PATCH v5 0/4] Check codeSigning extended key usage extension Lee, Chun-Yi
2021-03-23 3:55 ` [PATCH 1/4] X.509: Add CodeSigning extended key usage parsing Lee, Chun-Yi
2021-02-22 6:42 [PATCH v4 0/4] Check codeSigning extended key usage extension Lee, Chun-Yi
2021-02-22 6:42 ` [PATCH 1/4] X.509: Add CodeSigning extended key usage parsing Lee, Chun-Yi
2021-01-20 9:05 [PATCH v4 0/4] Check codeSigning extended key usage extension Lee, Chun-Yi
2021-01-20 9:05 ` [PATCH 1/4] X.509: Add CodeSigning extended key usage parsing Lee, Chun-Yi
2021-01-20 23:40 ` Jarkko Sakkinen
2021-01-21 4:23 ` joeyli
2021-01-21 14:32 ` Jarkko Sakkinen
2021-01-21 15:23 ` joeyli
2021-01-22 17:28 ` Jarkko Sakkinen
2021-01-27 9:40 ` David Howells
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