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PR/39525: Joachim Schueth, Frederik Sausmikat:

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cgd inadvertently encrypts blkno eight times to generate IV
This commit is contained in:
christos 2008-09-12 16:51:54 +00:00
parent fc978808f9
commit 8c6fb6faa5
3 changed files with 48 additions and 22 deletions
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12
sbin/cgdconfig/cgdconfig.8
View File

@ -1,4 +1,4 @@
.\" $NetBSD: cgdconfig.8,v 1.27 2008/05/13 09:31:06 wiz Exp $
.\" $NetBSD: cgdconfig.8,v 1.28 2008/09/12 16:51:55 christos Exp $
.\"
.\" Copyright (c) 2002, The NetBSD Foundation, Inc.
.\" All rights reserved.
@ -27,7 +27,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd May 10, 2008
.Dd September 12, 2008
.Dt CGDCONFIG 8
.Os
.Sh NAME
@ -97,7 +97,7 @@ This may need to prompt for multiple passphrases.
.It Fl g
Generate a paramsfile (to stdout).
.It Fl i Ar ivmeth
Specify the IV method (default: encblkno).
Specify the IV method (default: encblkno1).
.It Fl k Ar kgmeth
Specify the key generation method (default: pkcs5_pbkdf2/sha1).
.It Fl o Ar outfile
@ -316,7 +316,7 @@ cgd configuration file.
.Sh EXAMPLES
To set up and configure a cgd that uses AES with a 192 bit key
in CBC mode with the IV Method
.Sq encblkno
.Sq encblkno1
(encrypted block number):
.Bd -literal
# cgdconfig -g -o /etc/cgd/wd0e aes-cbc 192
@ -359,7 +359,7 @@ reads from stdin:
An example parameters file which uses PKCS#5 PBKDF2:
.Bd -literal
algorithm aes-cbc;
iv-method encblkno;
iv-method encblkno1;
keylength 128;
verify_method none;
keygen pkcs5_pbkdf2/sha1 {
@ -372,7 +372,7 @@ An example parameters file which uses PKCS#5 PBKDF2:
An example parameters file which stores its key locally:
.Bd -literal
algorithm aes-cbc;
iv-method encblkno;
iv-method encblkno1;
keylength 256;
verify_method none;
keygen storedkey key AAABAK3QO6d7xzLfrXTdsgg4 \\

23
sbin/cgdconfig/params.c
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@ -1,4 +1,4 @@
/* $NetBSD: params.c,v 1.23 2008/05/11 03:15:21 elric Exp $ */
/* $NetBSD: params.c,v 1.24 2008/09/12 16:51:55 christos Exp $ */
/*-
* Copyright (c) 2002, 2003 The NetBSD Foundation, Inc.
@ -31,7 +31,7 @@
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: params.c,v 1.23 2008/05/11 03:15:21 elric Exp $");
__RCSID("$NetBSD: params.c,v 1.24 2008/09/12 16:51:55 christos Exp $");
#endif
#include <sys/types.h>
@ -152,7 +152,7 @@ params_filldefaults(struct params *p)
if (p->verify_method == VERIFY_UNKNOWN)
p->verify_method = VERIFY_NONE;
if (!p->ivmeth)
p->ivmeth = string_fromcharstar("encblkno");
p->ivmeth = string_fromcharstar("encblkno1");
if (p->keylen == (size_t)-1) {
i = crypt_defaults_lookup(string_tocharstar(p->algorithm));
if (i != (size_t)-1) {
@ -178,6 +178,11 @@ params_filldefaults(struct params *p)
int
params_verify(const struct params *p)
{
static const char *encblkno[] = {
"encblkno", "encblkno1", "encblkno8"
};
static size_t i;
const char *meth;
if (!p->algorithm) {
warnx("unspecified algorithm");
@ -196,9 +201,15 @@ params_verify(const struct params *p)
warnx("unspecified IV method");
return 0;
}
if (strcmp("encblkno", string_tocharstar(p->ivmeth)))
warnx("unknown IV method \"%s\" (warning)",
string_tocharstar(p->ivmeth));
meth = string_tocharstar(p->ivmeth);
for (i = 0; i < __arraycount(encblkno); i++)
if (strcmp(encblkno[i], meth) == 0)
break;
if (i == __arraycount(encblkno))
warnx("unknown IV method \"%s\" (warning)", meth);
if (p->keylen == (size_t)-1) {
warnx("unspecified key length");
return 0;

35
share/man/man4/cgd.4
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@ -1,4 +1,4 @@
.\" $NetBSD: cgd.4,v 1.10 2008/04/30 13:10:53 martin Exp $
.\" $NetBSD: cgd.4,v 1.11 2008/09/12 16:51:55 christos Exp $
.\"
.\" Copyright (c) 2002, 2003 The NetBSD Foundation, Inc.
.\" All rights reserved.
@ -27,7 +27,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd March 11, 2006
.Dd September 12, 2008
.Dt CGD 4
.Os
.Sh NAME
@ -76,14 +76,29 @@ There are no performance advantages of using shorter keys.
The default key length is 128 bits.
.El
.Ss IV Methods
Currently, the only IV Method supported is
.Ar encblkno
(Encrypted Block Number).
This method encrypts the block number of the
physical disk block with the cipher and key provided and uses that as the
IV for CBC mode.
This method should ensure that each block has a different
IV and that the IV is reasonably unpredictable.
Currently, the following IV Methods are supported:
.Bl -tag -width encblkno1
.It encblkno1
This method encrypts the block number of the physical disk block once with
the cipher and key provided and uses the result as the IV for CBC mode.
This method should ensure that each block has a different IV and that the IV
is reasonably unpredictable.
This is the default method used by
.Xr cgdconfig 8
when configuring new
.Nm Ns 's .
.It encblkno8
This is the original IV method used by
.Nm
and provided for backward compatibility. It repeatedly encrypts the block
number of the physical disk block eight times and uses the result as the IV
for CBC mode.
This method should ensure that each block has a different IV and that the IV
is reasonably unpredictable.
The eightfold encryption was not intended and causes a notable
performance loss with little (if any) increase in security over a
single encryption.
.El
.Ss IOCTLS
A
.Nm