From: Andre Noll <maan@tuebingen.mpg.de>
Date: Tue, 28 Aug 2018 18:50:53 +0000 (+0200)
Subject: gcrypt: Factor out read_pem_rsa_params().
X-Git-Tag: v0.6.3~33^2~6
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=3699a583f3a7e9514c0f47b8b07f56b050430b67

gcrypt: Factor out read_pem_rsa_params().

We'll soon add a similar function which reads bignums from an RFC4716
key file, so it's good to separate this functionality from the rest
of get_private_key().

The patch also introduces struct rsa_params which contains
the six bignums used for RSA private key operations. This way
read_pem_rsa_params() only needs three arguments.
---

diff --git a/gcrypt.c b/gcrypt.c
index abc3272a..58fa507b 100644
--- a/gcrypt.c
+++ b/gcrypt.c
@@ -256,6 +256,54 @@ static int read_bignum(unsigned char *start, unsigned char *end, gcry_mpi_t *bn,
 	return cp - start;
 }
 
+struct rsa_params {
+	gcry_mpi_t n, e, d, p, q, u;
+};
+
+static int read_pem_rsa_params(unsigned char *start, unsigned char *end,
+		struct rsa_params *p)
+{
+	unsigned char *cp = start;
+	unsigned bits;
+	int ret;
+
+	ret = read_bignum(cp, end, &p->n, &bits);
+	if (ret < 0)
+		return ret;
+	cp += ret;
+	ret = read_bignum(cp, end, &p->e, NULL);
+	if (ret < 0)
+		goto release_n;
+	cp += ret;
+	ret = read_bignum(cp, end, &p->d, NULL);
+	if (ret < 0)
+		goto release_e;
+	cp += ret;
+	ret = read_bignum(cp, end, &p->p, NULL);
+	if (ret < 0)
+		goto release_d;
+	cp += ret;
+	ret = read_bignum(cp, end, &p->q, NULL);
+	if (ret < 0)
+		goto release_p;
+	cp += ret;
+	ret = read_bignum(cp, end, &p->u, NULL);
+	if (ret < 0)
+		goto release_q;
+	return bits;
+release_q:
+	gcry_mpi_release(p->q);
+release_p:
+	gcry_mpi_release(p->p);
+release_d:
+	gcry_mpi_release(p->d);
+release_e:
+	gcry_mpi_release(p->e);
+release_n:
+	gcry_mpi_release(p->n);
+	return ret;
+}
+
 static int find_privkey_bignum_offset(const unsigned char *data, int len)
 {
 	const unsigned char *p = data, *end = data + len;
@@ -290,9 +338,8 @@ static int find_privkey_bignum_offset(const unsigned char *data, int len)
 
 static int get_private_key(const char *key_file, struct asymmetric_key **result)
 {
-	gcry_mpi_t n = NULL, e = NULL, d = NULL, p = NULL, q = NULL,
-		u = NULL;
-	unsigned char *blob, *cp, *end;
+	struct rsa_params params;
+	unsigned char *blob, *end;
 	int ret;
 	unsigned bits;
 	gcry_error_t gret;
@@ -309,69 +356,40 @@ static int get_private_key(const char *key_file, struct asymmetric_key **result)
 	if (ret < 0)
 		goto free_blob;
 	PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
-	cp = blob + ret;
-
-	ret = read_bignum(cp, end, &n, &bits);
+	ret = read_pem_rsa_params(blob + ret, end, &params);
 	if (ret < 0)
 		goto free_blob;
-	cp += ret;
-
-	ret = read_bignum(cp, end, &e, NULL);
-	if (ret < 0)
-		goto release_n;
-	cp += ret;
-
-	ret = read_bignum(cp, end, &d, NULL);
-	if (ret < 0)
-		goto release_e;
-	cp += ret;
-
-	ret = read_bignum(cp, end, &p, NULL);
-	if (ret < 0)
-		goto release_d;
-	cp += ret;
-
-	ret = read_bignum(cp, end, &q, NULL);
-	if (ret < 0)
-		goto release_p;
-	cp += ret;
-	ret = read_bignum(cp, end, &u, NULL);
-	if (ret < 0)
-		goto release_q;
+	bits = ret;
 	/*
 	 * OpenSSL uses slightly different parameters than gcrypt. To use these
 	 * parameters we need to swap the values of p and q and recompute u.
 	 */
-	if (gcry_mpi_cmp(p, q) > 0) {
-		gcry_mpi_swap(p, q);
-		gcry_mpi_invm(u, p, q);
+	if (gcry_mpi_cmp(params.p, params.q) > 0) {
+		gcry_mpi_swap(params.p, params.q);
+		gcry_mpi_invm(params.u, params.p, params.q);
 	}
-	gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP,
-		n, e, d, p, q, u);
+	gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP, params.n,
+		params.e, params.d, params.p, params.q, params.u);
 
 	if (gret) {
 		PARA_ERROR_LOG("offset %zu: %s\n", erroff,
 			gcry_strerror(gcry_err_code(gret)));
 		ret = -E_SEXP_BUILD;
-		goto release_u;
+		goto free_params;
 	}
 	key = para_malloc(sizeof(*key));
 	key->sexp = sexp;
 	*result = key;
 	ret = bits;
 	PARA_INFO_LOG("succesfully read %d bit private key\n", ret);
-release_u:
-	gcry_mpi_release(u);
-release_q:
-	gcry_mpi_release(q);
-release_p:
-	gcry_mpi_release(p);
-release_d:
-	gcry_mpi_release(d);
-release_e:
-	gcry_mpi_release(e);
-release_n:
-	gcry_mpi_release(n);
+free_params:
+	gcry_mpi_release(params.n);
+	gcry_mpi_release(params.e);
+	gcry_mpi_release(params.d);
+	gcry_mpi_release(params.u);
+	gcry_mpi_release(params.p);
+	gcry_mpi_release(params.q);
+
 free_blob:
 	free(blob);
 	return ret;