commit 1da12e34ed69cec206f3a251a1e62ceeb694a6ea
author Richard Levitte <levitte@openssl.org> Mon Apr 25 20:28:54 2016 +0200
committer Richard Levitte <levitte@openssl.org> Wed Apr 27 15:07:53 2016 +0200
tree 5dfc32c8085b5e1cf77134786e778b861e38640d
parent 3aec886ed4af1ca945f5d10da2ce40e4538fe5fc

RSA, DSA, DH: Allow some given input to be NULL on already initialised keys

The diverse {RSA,DSA,DH}_set0_* functions are made to allow some
parameters to be NULL IF the corresponding numbers in the given key
structure have already been previously initialised.  Specifically,
this allows the addition of private components to be added to a key
that already has the public half, approximately like this:

    RSA_get0_key(rsa, NULL, &e, NULL);
    RSA_get0_factors(rsa, &p, &q);
    /* calculate new d */
    RSA_set0_key(rsa, NULL, NULL, d);

Reviewed-by: Matt Caswell <matt@openssl.org>

crypto/dsa/dsa_lib.c

diff --git a/crypto/dsa/dsa_lib.c b/crypto/dsa/dsa_lib.c
index facb97f..383b48b 100644
--- a/crypto/dsa/dsa_lib.c
+++ b/crypto/dsa/dsa_lib.c
@@ -315,14 +315,27 @@
 
 int DSA_set0_pqg(DSA *d, BIGNUM *p, BIGNUM *q, BIGNUM *g)
 {
-    if (p == NULL || q == NULL || g == NULL)
+    /* If the fields in d are NULL, the corresponding input
+     * parameters MUST be non-NULL.
+     *
+     * It is an error to give the results from get0 on d
+     * as input parameters.
+     */
+    if (p == d->p || q == d->q || g == d->g)
         return 0;
-    BN_free(d->p);
-    BN_free(d->q);
-    BN_free(d->g);
-    d->p = p;
-    d->q = q;
-    d->g = g;
+
+    if (p != NULL) {
+        BN_free(d->p);
+        d->p = p;
+    }
+    if (q != NULL) {
+        BN_free(d->q);
+        d->q = q;
+    }
+    if (g != NULL) {
+        BN_free(d->g);
+        d->g = g;
+    }
 
     return 1;
 }
@@ -337,14 +350,25 @@
 
 int DSA_set0_key(DSA *d, BIGNUM *pub_key, BIGNUM *priv_key)
 {
-    /* Note that it is valid for priv_key to be NULL */
-    if (pub_key == NULL)
+    /* If the pub_key in d is NULL, the corresponding input
+     * parameters MUST be non-NULL.  The priv_key field may
+     * be left NULL.
+     *
+     * It is an error to give the results from get0 on d
+     * as input parameters.
+     */
+    if (d->pub_key == pub_key
+        || (d->priv_key != NULL && priv_key != d->priv_key))
         return 0;
 
-    BN_free(d->pub_key);
-    BN_free(d->priv_key);
-    d->pub_key = pub_key;
-    d->priv_key = priv_key;
+    if (pub_key != NULL) {
+        BN_free(d->pub_key);
+        d->pub_key = pub_key;
+    }
+    if (priv_key != NULL) {
+        BN_free(d->priv_key);
+        d->priv_key = priv_key;
+    }
 
     return 1;
 }