Re: SSL_CTX_set_ssl_version changes security level
On Mon, 2020-05-11 at 13:37 -0700, Benjamin Kaduk via openssl-users wrote: > On Tue, May 12, 2020 at 05:22:29AM +0900, NAKANO Takuho wrote: > > 2020年5月12日(火) 0:31 Benjamin Kaduk : > > > > > OS-vendor customization > > > > Thank you. That's very helpful. I get how to configure (but don't > > know why...). > > > > On CentOS 8: > > First result of SSL_CTX_get_security_level depends on > > A: /etc/pki/tls/openssl.cnf . > > > > To be more precise, set "CipherString = @SECLEVEL=5:..." > > or "CipherString = @SECLEVEL=0:..." in > > B: /etc/crypto-policies/back-ends/opensslcnf.config > > that is included by A. > > > > *BUT* second result of SSL_CTX_get_security_level depends on > > C: /etc/crypto-policies/back-ends/openssl.config > > (I assume SSL_CTX_set_ssl_version internally refer this file). > > File C has a single line beginning with: > > @SECLEVEL=2:kEECDH:.. > > If I change this level, the second result changes. > > Maybe it's on RHEL8 patch (system-cipherlist.patch). > > https://src.fedoraproject.org/rpms/openssl/blob/master/f/openssl-1.1.1-system-cipherlist.patch > suggests (the ssl.h chunk) that this patch does force the use of the > "system > profile" as the default cipher list. Yes, on Fedora/RHEL 8 you need to replace the cipher strings in both /etc/crypto-policies/back-ends/openssl.config and /etc/crypto- policies/back-ends/opensslcnf.config config files or you have to override the cipher string with a non-default one from the application. -- Tomáš Mráz No matter how far down the wrong road you've gone, turn back. Turkish proverb [You'll know whether the road is wrong if you carefully listen to your conscience.]
Re: SSL_CTX_set_ssl_version changes security level
> https://src.fedoraproject.org/rpms/openssl/blob/master/f/openssl-1.1.1-system-cipherlist.patch
> suggests (the ssl.h chunk) that this patch does force the use of the "system
> profile" as the default cipher list.
https://src.fedoraproject.org/rpms/openssl/blob/master/f/openssl.spec
"./Configure" with option below:
--system-ciphers-file=%{_sysconfdir}/crypto-policies/back-ends/openssl.config
this path is where I pointed.
Takuho
Re: SSL_CTX_set_ssl_version changes security level
On Tue, May 12, 2020 at 05:22:29AM +0900, NAKANO Takuho wrote: > 2020年5月12日(火) 0:31 Benjamin Kaduk : > > > OS-vendor customization > > Thank you. That's very helpful. I get how to configure (but don't know > why...). > > On CentOS 8: > First result of SSL_CTX_get_security_level depends on > A: /etc/pki/tls/openssl.cnf . > > To be more precise, set "CipherString = @SECLEVEL=5:..." > or "CipherString = @SECLEVEL=0:..." in > B: /etc/crypto-policies/back-ends/opensslcnf.config > that is included by A. > > *BUT* second result of SSL_CTX_get_security_level depends on > C: /etc/crypto-policies/back-ends/openssl.config > (I assume SSL_CTX_set_ssl_version internally refer this file). > File C has a single line beginning with: > @SECLEVEL=2:kEECDH:.. > If I change this level, the second result changes. > Maybe it's on RHEL8 patch (system-cipherlist.patch). https://src.fedoraproject.org/rpms/openssl/blob/master/f/openssl-1.1.1-system-cipherlist.patch suggests (the ssl.h chunk) that this patch does force the use of the "system profile" as the default cipher list. -Ben
Re: SSL_CTX_set_ssl_version changes security level
2020年5月12日(火) 0:31 Benjamin Kaduk :
>
> On Mon, May 11, 2020 at 05:01:27PM +0900, NAKANO Takuho wrote:
> > Hello,
> >
> > I've found SSL_CTX_set_ssl_version changes security level:
> >
> > =
> > int main(void){
> > int i;
> > struct ssl_ctx_st *ctx = SSL_CTX_new(SSLv23_method());
> >
> > printf("seclevel: %d\n", SSL_CTX_get_security_level(ctx));
> > // 0--5 any
> >
> > i = SSL_CTX_set_ssl_version(ctx, SSLv23_client_method());
> > printf("SSL_CTX_set_ssl_version result: %d\n", i);
> > // i ==1; success
> >
> > printf("seclevel: %d\n", SSL_CTX_get_security_level(ctx));
> > // result 2
> >
> > return 0;
> > }
> > =
> >
> > OS: CentOS 8
> > OpenSSL 1.1.1c FIPS 28 May 2019
> >
> > Are there any reasons?
> > I know SSLv23_method is deprecated. That does not matter.
>
> Note that SSL_CTX_set_ssl_version() has to re-set the cipher list
> to filter out ciphers unsupported by the new version. It uses
> the default cipher list as its starting point, which I assume on
> EL8 includes the security level in the cipher string.
> You can set the cipher list (and security level) back to what you
> want afterward, but I note that this behavior is a result of the
> OS-vendor customization and not inherent to openssl.
> OS-vendor customization
Thank you. That's very helpful. I get how to configure (but don't know why...).
On CentOS 8:
First result of SSL_CTX_get_security_level depends on
A: /etc/pki/tls/openssl.cnf .
To be more precise, set "CipherString = @SECLEVEL=5:..."
or "CipherString = @SECLEVEL=0:..." in
B: /etc/crypto-policies/back-ends/opensslcnf.config
that is included by A.
*BUT* second result of SSL_CTX_get_security_level depends on
C: /etc/crypto-policies/back-ends/openssl.config
(I assume SSL_CTX_set_ssl_version internally refer this file).
File C has a single line beginning with:
@SECLEVEL=2:kEECDH:..
If I change this level, the second result changes.
Maybe it's on RHEL8 patch (system-cipherlist.patch).
If I tried on Ubuntu 18.04 with "OpenSSL 1.1.1d 10 Sep 2019",
security level diddn't change.
Regards,
Takuho
Re: SSL_CTX_set_ssl_version changes security level
On Mon, May 11, 2020 at 05:01:27PM +0900, NAKANO Takuho wrote:
> Hello,
>
> I've found SSL_CTX_set_ssl_version changes security level:
>
> =
> int main(void){
> int i;
> struct ssl_ctx_st *ctx = SSL_CTX_new(SSLv23_method());
>
> printf("seclevel: %d\n", SSL_CTX_get_security_level(ctx));
> // 0--5 any
>
> i = SSL_CTX_set_ssl_version(ctx, SSLv23_client_method());
> printf("SSL_CTX_set_ssl_version result: %d\n", i);
> // i ==1; success
>
> printf("seclevel: %d\n", SSL_CTX_get_security_level(ctx));
> // result 2
>
> return 0;
> }
> =
>
> OS: CentOS 8
> OpenSSL 1.1.1c FIPS 28 May 2019
>
> Are there any reasons?
> I know SSLv23_method is deprecated. That does not matter.
Note that SSL_CTX_set_ssl_version() has to re-set the cipher list
to filter out ciphers unsupported by the new version. It uses
the default cipher list as its starting point, which I assume on
EL8 includes the security level in the cipher string.
You can set the cipher list (and security level) back to what you
want afterward, but I note that this behavior is a result of the
OS-vendor customization and not inherent to openssl.
-Ben
SSL_CTX_set_ssl_version changes security level
Hello,
I've found SSL_CTX_set_ssl_version changes security level:
=
int main(void){
int i;
struct ssl_ctx_st *ctx = SSL_CTX_new(SSLv23_method());
printf("seclevel: %d\n", SSL_CTX_get_security_level(ctx));
// 0--5 any
i = SSL_CTX_set_ssl_version(ctx, SSLv23_client_method());
printf("SSL_CTX_set_ssl_version result: %d\n", i);
// i ==1; success
printf("seclevel: %d\n", SSL_CTX_get_security_level(ctx));
// result 2
return 0;
}
=
OS: CentOS 8
OpenSSL 1.1.1c FIPS 28 May 2019
Are there any reasons?
I know SSLv23_method is deprecated. That does not matter.
Regards,
Takuho
