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Miller" , "AKASHI, Takahiro" , Thiago Jung Bauermann Subject: [PATCH v6 03/12] PKCS#7: Introduce pkcs7_get_digest() Date: Fri, 16 Mar 2018 17:38:28 -0300 X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180316203837.10174-1-bauerman@linux.vnet.ibm.com> References: <20180316203837.10174-1-bauerman@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18031620-0008-0000-0000-00000977E340 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008686; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000254; SDB=6.01004029; UDB=6.00511020; IPR=6.00783317; MB=3.00020079; MTD=3.00000008; XFM=3.00000015; UTC=2018-03-16 20:39:37 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18031620-0009-0000-0000-0000466BDD2C Message-Id: <20180316203837.10174-4-bauerman@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2018-03-16_13:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1803160244 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP IMA will need to access the digest of the PKCS7 message (as calculated by the kernel) before the signature is verified, so introduce pkcs7_get_digest() for that purpose. Also, modify pkcs7_digest() to detect when the digest was already calculated so that it doesn't have to do redundant work. Verifying that sinfo->sig->digest isn't NULL is sufficient because both places which allocate sinfo->sig (pkcs7_parse_message() and pkcs7_note_signed_info()) use kzalloc() so sig->digest is always initialized to zero. Signed-off-by: Thiago Jung Bauermann Cc: David Howells Cc: Herbert Xu Cc: "David S. Miller" Reviewed-by: Mimi Zohar --- crypto/asymmetric_keys/pkcs7_verify.c | 25 +++++++++++++++++++++++++ include/crypto/pkcs7.h | 3 +++ 2 files changed, 28 insertions(+) diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c index 39e6de0c2761..bd02360f8be5 100644 --- a/crypto/asymmetric_keys/pkcs7_verify.c +++ b/crypto/asymmetric_keys/pkcs7_verify.c @@ -33,6 +33,10 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7, kenter(",%u,%s", sinfo->index, sinfo->sig->hash_algo); + /* The digest was calculated already. */ + if (sig->digest) + return 0; + if (!sinfo->sig->hash_algo) return -ENOPKG; @@ -122,6 +126,27 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7, return ret; } +int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf, u8 *len) +{ + struct pkcs7_signed_info *sinfo = pkcs7->signed_infos; + int ret; + + /* + * This function doesn't support messages with more than one signature. + */ + if (sinfo == NULL || sinfo->next != NULL) + return -EBADMSG; + + ret = pkcs7_digest(pkcs7, sinfo); + if (ret) + return ret; + + *buf = sinfo->sig->digest; + *len = sinfo->sig->digest_size; + + return 0; +} + /* * Find the key (X.509 certificate) to use to verify a PKCS#7 message. PKCS#7 * uses the issuer's name and the issuing certificate serial number for diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h index 6f51d0cb6d12..cfaea9c37f4a 100644 --- a/include/crypto/pkcs7.h +++ b/include/crypto/pkcs7.h @@ -46,4 +46,7 @@ extern int pkcs7_verify(struct pkcs7_message *pkcs7, extern int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7, const void *data, size_t datalen); +extern int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf, + u8 *len); + #endif /* _CRYPTO_PKCS7_H */