generic-library/openssl
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Add additional DigestInfo checks.

Browse Source 
Reencode DigestInto in DER and check against the original: this
will reject any improperly encoded DigestInfo structures.

Note: this is a precautionary measure, there is no known attack
which can exploit this.

Thanks to Brian Smith for reporting this issue.
Reviewed-by: Tim Hudson <tjh@openssl.org>
This commit is contained in:
Dr. Stephen Henson 2014-09-25 23:28:48 +01:00
parent 0853b2c5e4
commit 5df07a7210
2 changed files with 32 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
CHANGES
View File

@ -405,6 +405,18 @@
bogus results, with non-infinity inputs mapped to infinity too.)
[Bodo Moeller]
Changes between 1.0.1i and 1.0.1j [xx XXX xxxx]
*) Add additional DigestInfo checks.
Reencode DigestInto in DER and check against the original when
verifying RSA signature: this will reject any improperly encoded
DigestInfo structures.
Note: this is a precautionary measure and no attacks are currently known.
[Steve Henson]
Changes between 1.0.1g and 1.0.1h [5 Jun 2014]
*) Fix for SSL/TLS MITM flaw. An attacker using a carefully crafted

21
crypto/rsa/rsa_sign.c
View File

@ -151,6 +151,25 @@ int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
return(ret);
}
/*
* Check DigestInfo structure does not contain extraneous data by reencoding
* using DER and checking encoding against original.
*/
static int rsa_check_digestinfo(X509_SIG *sig, const unsigned char *dinfo, int dinfolen)
{
unsigned char *der = NULL;
int derlen;
int ret = 0;
derlen = i2d_X509_SIG(sig, &der);
if (derlen <= 0)
return 0;
if (derlen == dinfolen && !memcmp(dinfo, der, derlen))
ret = 1;
OPENSSL_cleanse(der, derlen);
OPENSSL_free(der);
return ret;
}
int int_rsa_verify(int dtype, const unsigned char *m,
unsigned int m_len,
unsigned char *rm, size_t *prm_len,
@ -228,7 +247,7 @@ int int_rsa_verify(int dtype, const unsigned char *m,
if (sig == NULL) goto err;
/* Excess data can be used to create forgeries */
if(p != s+i)
if(p != s+i || !rsa_check_digestinfo(sig, s, i))
{
RSAerr(RSA_F_INT_RSA_VERIFY,RSA_R_BAD_SIGNATURE);
goto err;