[openssl] master update
Matt Caswell
matt at openssl.org
Tue Sep 10 10:48:04 UTC 2019
The branch master has been updated
via 5840ed0cd1e6487d247efbc1a04136a41d7b3a37 (commit)
from fa3eb248e29ca8031e6a14e8a2c6f3cd58b5450e (commit)
- Log -----------------------------------------------------------------
commit 5840ed0cd1e6487d247efbc1a04136a41d7b3a37
Author: Bernd Edlinger <bernd.edlinger at hotmail.de>
Date: Sun Sep 1 00:16:28 2019 +0200
Fix a padding oracle in PKCS7_dataDecode and CMS_decrypt_set1_pkey
An attack is simple, if the first CMS_recipientInfo is valid but the
second CMS_recipientInfo is chosen ciphertext. If the second
recipientInfo decodes to PKCS #1 v1.5 form plaintext, the correct
encryption key will be replaced by garbage, and the message cannot be
decoded, but if the RSA decryption fails, the correct encryption key is
used and the recipient will not notice the attack.
As a work around for this potential attack the length of the decrypted
key must be equal to the cipher default key length, in case the
certifiate is not given and all recipientInfo are tried out.
The old behaviour can be re-enabled in the CMS code by setting the
CMS_DEBUG_DECRYPT flag.
Reviewed-by: Matt Caswell <matt at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9777)
-----------------------------------------------------------------------
Summary of changes:
CHANGES | 14 ++++++++++++++
crypto/cms/cms_env.c | 18 +++++++++++++++++-
crypto/cms/cms_lcl.h | 2 ++
crypto/cms/cms_smime.c | 4 ++++
crypto/pkcs7/pk7_doit.c | 12 ++++++++----
5 files changed, 45 insertions(+), 5 deletions(-)
diff --git a/CHANGES b/CHANGES
index 3d2f94303a..29ab546d91 100644
--- a/CHANGES
+++ b/CHANGES
@@ -27,6 +27,20 @@
(CVE-2019-1547)
[Billy Bob Brumley]
+ *) Fixed a padding oracle in PKCS7_dataDecode and CMS_decrypt_set1_pkey.
+ An attack is simple, if the first CMS_recipientInfo is valid but the
+ second CMS_recipientInfo is chosen ciphertext. If the second
+ recipientInfo decodes to PKCS #1 v1.5 form plaintext, the correct
+ encryption key will be replaced by garbage, and the message cannot be
+ decoded, but if the RSA decryption fails, the correct encryption key is
+ used and the recipient will not notice the attack.
+ As a work around for this potential attack the length of the decrypted
+ key must be equal to the cipher default key length, in case the
+ certifiate is not given and all recipientInfo are tried out.
+ The old behaviour can be re-enabled in the CMS code by setting the
+ CMS_DEBUG_DECRYPT flag.
+ [Bernd Edlinger]
+
*) Early start up entropy quality from the DEVRANDOM seed source has been
improved for older Linux systems. The RAND subsystem will wait for
/dev/random to be producing output before seeding from /dev/urandom.
diff --git a/crypto/cms/cms_env.c b/crypto/cms/cms_env.c
index acfbf8c50a..27e98ce0a7 100644
--- a/crypto/cms/cms_env.c
+++ b/crypto/cms/cms_env.c
@@ -363,6 +363,7 @@ static int cms_RecipientInfo_ktri_decrypt(CMS_ContentInfo *cms,
unsigned char *ek = NULL;
size_t eklen;
int ret = 0;
+ size_t fixlen = 0;
CMS_EncryptedContentInfo *ec;
ec = cms->d.envelopedData->encryptedContentInfo;
@@ -371,6 +372,19 @@ static int cms_RecipientInfo_ktri_decrypt(CMS_ContentInfo *cms,
return 0;
}
+ if (cms->d.envelopedData->encryptedContentInfo->havenocert
+ && !cms->d.envelopedData->encryptedContentInfo->debug) {
+ X509_ALGOR *calg = ec->contentEncryptionAlgorithm;
+ const EVP_CIPHER *ciph = EVP_get_cipherbyobj(calg->algorithm);
+
+ if (ciph == NULL) {
+ CMSerr(CMS_F_CMS_RECIPIENTINFO_KTRI_DECRYPT, CMS_R_UNKNOWN_CIPHER);
+ return 0;
+ }
+
+ fixlen = EVP_CIPHER_key_length(ciph);
+ }
+
ktri->pctx = EVP_PKEY_CTX_new(pkey, NULL);
if (ktri->pctx == NULL)
return 0;
@@ -401,7 +415,9 @@ static int cms_RecipientInfo_ktri_decrypt(CMS_ContentInfo *cms,
if (EVP_PKEY_decrypt(ktri->pctx, ek, &eklen,
ktri->encryptedKey->data,
- ktri->encryptedKey->length) <= 0) {
+ ktri->encryptedKey->length) <= 0
+ || eklen == 0
+ || (fixlen != 0 && eklen != fixlen)) {
CMSerr(CMS_F_CMS_RECIPIENTINFO_KTRI_DECRYPT, CMS_R_CMS_LIB);
goto err;
}
diff --git a/crypto/cms/cms_lcl.h b/crypto/cms/cms_lcl.h
index 08f086b589..40d9c4bb7d 100644
--- a/crypto/cms/cms_lcl.h
+++ b/crypto/cms/cms_lcl.h
@@ -125,6 +125,8 @@ struct CMS_EncryptedContentInfo_st {
size_t keylen;
/* Set to 1 if we are debugging decrypt and don't fake keys for MMA */
int debug;
+ /* Set to 1 if we have no cert and need extra safety measures for MMA */
+ int havenocert;
};
struct CMS_RecipientInfo_st {
diff --git a/crypto/cms/cms_smime.c b/crypto/cms/cms_smime.c
index 5f1a47d768..ae95ff2dd2 100644
--- a/crypto/cms/cms_smime.c
+++ b/crypto/cms/cms_smime.c
@@ -743,6 +743,10 @@ int CMS_decrypt(CMS_ContentInfo *cms, EVP_PKEY *pk, X509 *cert,
cms->d.envelopedData->encryptedContentInfo->debug = 1;
else
cms->d.envelopedData->encryptedContentInfo->debug = 0;
+ if (!cert)
+ cms->d.envelopedData->encryptedContentInfo->havenocert = 1;
+ else
+ cms->d.envelopedData->encryptedContentInfo->havenocert = 0;
if (!pk && !cert && !dcont && !out)
return 1;
if (pk && !CMS_decrypt_set1_pkey(cms, pk, cert))
diff --git a/crypto/pkcs7/pk7_doit.c b/crypto/pkcs7/pk7_doit.c
index cc09bbf1f2..030718a1cb 100644
--- a/crypto/pkcs7/pk7_doit.c
+++ b/crypto/pkcs7/pk7_doit.c
@@ -137,7 +137,8 @@ static int pkcs7_encode_rinfo(PKCS7_RECIP_INFO *ri,
}
static int pkcs7_decrypt_rinfo(unsigned char **pek, int *peklen,
- PKCS7_RECIP_INFO *ri, EVP_PKEY *pkey)
+ PKCS7_RECIP_INFO *ri, EVP_PKEY *pkey,
+ size_t fixlen)
{
EVP_PKEY_CTX *pctx = NULL;
unsigned char *ek = NULL;
@@ -170,7 +171,9 @@ static int pkcs7_decrypt_rinfo(unsigned char **pek, int *peklen,
}
if (EVP_PKEY_decrypt(pctx, ek, &eklen,
- ri->enc_key->data, ri->enc_key->length) <= 0) {
+ ri->enc_key->data, ri->enc_key->length) <= 0
+ || eklen == 0
+ || (fixlen != 0 && eklen != fixlen)) {
ret = 0;
PKCS7err(PKCS7_F_PKCS7_DECRYPT_RINFO, ERR_R_EVP_LIB);
goto err;
@@ -499,13 +502,14 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
for (i = 0; i < sk_PKCS7_RECIP_INFO_num(rsk); i++) {
ri = sk_PKCS7_RECIP_INFO_value(rsk, i);
- if (pkcs7_decrypt_rinfo(&ek, &eklen, ri, pkey) < 0)
+ if (pkcs7_decrypt_rinfo(&ek, &eklen, ri, pkey,
+ EVP_CIPHER_key_length(evp_cipher)) < 0)
goto err;
ERR_clear_error();
}
} else {
/* Only exit on fatal errors, not decrypt failure */
- if (pkcs7_decrypt_rinfo(&ek, &eklen, ri, pkey) < 0)
+ if (pkcs7_decrypt_rinfo(&ek, &eklen, ri, pkey, 0) < 0)
goto err;
ERR_clear_error();
}
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