From: "Stephan Müller" <smueller@chronox.de>
To: herbert@gondor.apana.org.au
Cc: linux-crypto@vger.kernel.org,
Marcelo Cerri <marcelo.cerri@canonical.com>,
Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Subject: [PATCH 2/3] lib/mpi: Add mpi_sub_ui()
Date: Fri, 10 Jul 2020 12:10:40 +0200 [thread overview]
Message-ID: <4577235.31r3eYUQgx@positron.chronox.de> (raw)
In-Reply-To: <2543601.mvXUDI8C0e@positron.chronox.de>
Add mpi_sub_ui() based on Gnu PG mpz_sub_ui() from mpz/aors_ui.h
adapting the code to the kernel's structures and coding style and also
removing the defines used to produce mpz_sub_ui() and mpz_add_ui()
from the same code.
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
include/linux/mpi.h | 3 +++
lib/mpi/Makefile | 1 +
lib/mpi/mpi-sub-ui.c | 60 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 64 insertions(+)
create mode 100644 lib/mpi/mpi-sub-ui.c
diff --git a/include/linux/mpi.h b/include/linux/mpi.h
index 7bd6d8af0004..5d906dfbf3ed 100644
--- a/include/linux/mpi.h
+++ b/include/linux/mpi.h
@@ -63,6 +63,9 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod);
int mpi_cmp_ui(MPI u, ulong v);
int mpi_cmp(MPI u, MPI v);
+/*-- mpi-sub-ui.c --*/
+int mpi_sub_ui(MPI w, MPI u, unsigned long vval);
+
/*-- mpi-bit.c --*/
void mpi_normalize(MPI a);
unsigned mpi_get_nbits(MPI a);
diff --git a/lib/mpi/Makefile b/lib/mpi/Makefile
index d5874a7f5ff9..43b8fce14079 100644
--- a/lib/mpi/Makefile
+++ b/lib/mpi/Makefile
@@ -16,6 +16,7 @@ mpi-y = \
mpicoder.o \
mpi-bit.o \
mpi-cmp.o \
+ mpi-sub-ui.o \
mpih-cmp.o \
mpih-div.o \
mpih-mul.o \
diff --git a/lib/mpi/mpi-sub-ui.c b/lib/mpi/mpi-sub-ui.c
new file mode 100644
index 000000000000..fa6b085bac36
--- /dev/null
+++ b/lib/mpi/mpi-sub-ui.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* mpi-sub-ui.c - MPI functions
+ * Copyright 1991, 1993, 1994, 1996, 1999-2002, 2004, 2012, 2013, 2015
+ * Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ * Actually it's the same code with only minor changes in the
+ * way the data is stored; this is to support the abstraction
+ * of an optional secure memory allocation which may be used
+ * to avoid revealing of sensitive data due to paging etc.
+ * The GNU MP Library itself is published under the LGPL;
+ * however I decided to publish this code under the plain GPL.
+ */
+
+#include "mpi-internal.h"
+
+int mpi_sub_ui(MPI w, MPI u, unsigned long vval)
+{
+ if (u->nlimbs == 0) {
+ if (mpi_resize(w, 1) < 0)
+ return -ENOMEM;
+ w->d[0] = vval;
+ w->nlimbs = (vval != 0);
+ w->sign = (vval != 0);
+ return 0;
+ }
+
+ /* If not space for W (and possible carry), increase space. */
+ if (mpi_resize(w, u->nlimbs + 1))
+ return -ENOMEM;
+
+ if (u->sign) {
+ mpi_limb_t cy;
+
+ cy = mpihelp_add_1(w->d, u->d, u->nlimbs, (mpi_limb_t) vval);
+ w->d[u->nlimbs] = cy;
+ w->nlimbs = u->nlimbs + cy;
+ w->sign = 1;
+ } else {
+ /* The signs are different. Need exact comparison to determine
+ * which operand to subtract from which.
+ */
+ if (u->nlimbs == 1 && u->d[0] < vval) {
+ w->d[0] = vval - u->d[0];
+ w->nlimbs = 1;
+ w->sign = 1;
+ } else {
+ mpihelp_sub_1(w->d, u->d, u->nlimbs, (mpi_limb_t) vval);
+ /* Size can decrease with at most one limb. */
+ w->nlimbs = (u->nlimbs - (w->d[u->nlimbs - 1] == 0));
+ w->sign = 0;
+ }
+ }
+
+ mpi_normalize(w);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(mpi_sub_ui);
--
2.26.2
next prev parent reply other threads:[~2020-07-10 10:16 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 10:09 [PATCH 0/3] DH: SP800-56A rev 3 compliant shared secret Stephan Müller
2020-07-10 10:10 ` [PATCH 1/3] crypto: ECDH - check validity of Z before export Stephan Müller
2020-07-10 10:10 ` Stephan Müller [this message]
2020-07-10 14:42 ` [PATCH 2/3] lib/mpi: Add mpi_sub_ui() Ard Biesheuvel
2020-07-10 15:10 ` Stephan Mueller
2020-07-10 10:15 ` [PATCH 3/3] crypto: DH - check validity of Z before export Stephan Müller
2020-07-12 16:38 ` [PATCH v2 0/5] DH: SP800-56A rev 3 compliant validation checks Stephan Müller
2020-07-12 16:39 ` [PATCH v2 1/5] crypto: ECDH - check validity of Z before export Stephan Müller
2020-07-12 18:02 ` Vitaly Chikunov
2020-07-15 13:17 ` Marcelo Henrique Cerri
2020-07-12 16:39 ` [PATCH v2 2/5] lib/mpi: Add mpi_sub_ui() Stephan Müller
2020-07-16 7:30 ` Herbert Xu
2020-07-16 8:41 ` Ard Biesheuvel
2020-07-16 12:50 ` Marcelo Henrique Cerri
2020-07-16 13:09 ` Ard Biesheuvel
2020-07-16 13:41 ` Marcelo Henrique Cerri
2020-07-16 13:53 ` Ard Biesheuvel
2020-07-16 14:23 ` Marcelo Henrique Cerri
2020-07-16 14:37 ` Ard Biesheuvel
2020-07-16 14:56 ` Marcelo Henrique Cerri
2020-07-16 15:20 ` Ard Biesheuvel
2020-07-12 16:40 ` [PATCH v2 3/5] crypto: DH - check validity of Z before export Stephan Müller
2020-07-15 13:17 ` Marcelo Henrique Cerri
2020-07-12 16:40 ` [PATCH v2 4/5] crypto: DH SP800-56A rev 3 local public key validation Stephan Müller
2020-07-15 13:18 ` Marcelo Henrique Cerri
2020-07-12 16:42 ` [PATCH v2 5/5] crypto: ECDH " Stephan Müller
2020-07-12 18:06 ` Vitaly Chikunov
2020-07-13 5:04 ` Stephan Mueller
2020-07-13 5:59 ` Vitaly Chikunov
2020-07-13 6:02 ` Stephan Müller
2020-07-15 13:19 ` Marcelo Henrique Cerri
2020-07-20 17:05 ` [PATCH v3 0/5] DH: SP800-56A rev 3 compliant validation checks Stephan Müller
2020-07-20 17:07 ` [PATCH v3 1/5] crypto: ECDH - check validity of Z before export Stephan Müller
2020-07-22 13:11 ` Vitaly Chikunov
2020-07-24 17:47 ` Neil Horman
2020-07-20 17:08 ` [PATCH v3 2/5] lib/mpi: Add mpi_sub_ui() Stephan Müller
2020-07-20 17:08 ` [PATCH v3 3/5] crypto: DH - check validity of Z before export Stephan Müller
2020-07-24 18:02 ` Neil Horman
2020-07-20 17:08 ` [PATCH v3 4/5] crypto: DH SP800-56A rev 3 local public key validation Stephan Müller
2020-07-20 17:09 ` [PATCH v3 5/5] crypto: ECDH " Stephan Müller
2020-07-21 11:35 ` [PATCH v3 0/5] DH: SP800-56A rev 3 compliant validation checks Marcelo Henrique Cerri
2020-07-31 13:29 ` Herbert Xu
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