KEYS: Add placeholder for KDF usage with DH
The values computed during Diffie-Hellman key exchange are often used
in combination with key derivation functions to create cryptographic
keys. Add a placeholder for a later implementation to configure a
key derivation function that will transform the Diffie-Hellman
result returned by the KEYCTL_DH_COMPUTE command.
[This patch was stripped down from a patch produced by Mat Martineau that
had a bug in the compat code - so for the moment Stephan's patch simply
requires that the placeholder argument must be NULL]
Original-signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
diff --git a/security/keys/compat.c b/security/keys/compat.c
index c8783b3..36c80bf 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -134,7 +134,7 @@
case KEYCTL_DH_COMPUTE:
return keyctl_dh_compute(compat_ptr(arg2), compat_ptr(arg3),
- arg4);
+ arg4, compat_ptr(arg5));
default:
return -EOPNOTSUPP;
diff --git a/security/keys/dh.c b/security/keys/dh.c
index 880505a..531ed2e 100644
--- a/security/keys/dh.c
+++ b/security/keys/dh.c
@@ -78,7 +78,8 @@
}
long keyctl_dh_compute(struct keyctl_dh_params __user *params,
- char __user *buffer, size_t buflen)
+ char __user *buffer, size_t buflen,
+ void __user *reserved)
{
long ret;
MPI base, private, prime, result;
@@ -97,6 +98,11 @@
goto out;
}
+ if (reserved) {
+ ret = -EINVAL;
+ goto out;
+ }
+
keylen = mpi_from_key(pcopy.prime, buflen, &prime);
if (keylen < 0 || !prime) {
/* buflen == 0 may be used to query the required buffer size,
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 8ec7a52..a705a7d 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -260,10 +260,11 @@
#ifdef CONFIG_KEY_DH_OPERATIONS
extern long keyctl_dh_compute(struct keyctl_dh_params __user *, char __user *,
- size_t);
+ size_t, void __user *);
#else
static inline long keyctl_dh_compute(struct keyctl_dh_params __user *params,
- char __user *buffer, size_t buflen)
+ char __user *buffer, size_t buflen,
+ void __user *reserved)
{
return -EOPNOTSUPP;
}
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 3b135a0..d580ad0 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1688,8 +1688,8 @@
case KEYCTL_DH_COMPUTE:
return keyctl_dh_compute((struct keyctl_dh_params __user *) arg2,
- (char __user *) arg3,
- (size_t) arg4);
+ (char __user *) arg3, (size_t) arg4,
+ (void __user *) arg5);
default:
return -EOPNOTSUPP;