Merge pull request #817 from antonio-nino-diaz-arm/an/timingsafe
Import constant-time bcmp() and use it where necessary
diff --git a/drivers/auth/mbedtls/mbedtls_crypto.c b/drivers/auth/mbedtls/mbedtls_crypto.c
index 1a96e8f..11d3ede 100644
--- a/drivers/auth/mbedtls/mbedtls_crypto.c
+++ b/drivers/auth/mbedtls/mbedtls_crypto.c
@@ -217,7 +217,7 @@
}
/* Compare values */
- rc = memcmp(data_hash, hash, mbedtls_md_get_size(md_info));
+ rc = timingsafe_bcmp(data_hash, hash, mbedtls_md_get_size(md_info));
if (rc != 0) {
return CRYPTO_ERR_HASH;
}
diff --git a/drivers/auth/mbedtls/mbedtls_x509_parser.c b/drivers/auth/mbedtls/mbedtls_x509_parser.c
index 73da9d1..f9485de 100644
--- a/drivers/auth/mbedtls/mbedtls_x509_parser.c
+++ b/drivers/auth/mbedtls/mbedtls_x509_parser.c
@@ -392,7 +392,7 @@
if (sig_alg1.len != sig_alg2.len) {
return IMG_PARSER_ERR_FORMAT;
}
- if (0 != memcmp(sig_alg1.p, sig_alg2.p, sig_alg1.len)) {
+ if (0 != timingsafe_bcmp(sig_alg1.p, sig_alg2.p, sig_alg1.len)) {
return IMG_PARSER_ERR_FORMAT;
}
memcpy(&sig_alg, &sig_alg1, sizeof(sig_alg));
diff --git a/include/lib/stdlib/string.h b/include/lib/stdlib/string.h
index 9beeb44..902d9c1 100644
--- a/include/lib/stdlib/string.h
+++ b/include/lib/stdlib/string.h
@@ -61,6 +61,7 @@
int strncmp(const char *, const char *, size_t) __pure;
size_t strnlen(const char *, size_t) __pure;
int strcasecmp(const char *, const char *);
+int timingsafe_bcmp(const void *, const void *, size_t);
__END_DECLS
diff --git a/lib/stdlib/stdlib.mk b/lib/stdlib/stdlib.mk
index 4ff405f..5332717 100644
--- a/lib/stdlib/stdlib.mk
+++ b/lib/stdlib/stdlib.mk
@@ -42,7 +42,8 @@
strlen.c \
strncmp.c \
strnlen.c \
- subr_prf.c)
+ subr_prf.c \
+ timingsafe_bcmp.c)
INCLUDES += -Iinclude/lib/stdlib \
-Iinclude/lib/stdlib/sys
diff --git a/lib/stdlib/timingsafe_bcmp.c b/lib/stdlib/timingsafe_bcmp.c
new file mode 100644
index 0000000..d098158
--- /dev/null
+++ b/lib/stdlib/timingsafe_bcmp.c
@@ -0,0 +1,36 @@
+/* $OpenBSD: timingsafe_bcmp.c,v 1.3 2015/08/31 02:53:57 guenther Exp $ */
+/*
+ * Copyright (c) 2010 Damien Miller. All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <string.h>
+
+int __timingsafe_bcmp(const void *, const void *, size_t);
+
+int
+__timingsafe_bcmp(const void *b1, const void *b2, size_t n)
+{
+ const unsigned char *p1 = b1, *p2 = b2;
+ int ret = 0;
+
+ for (; n > 0; n--)
+ ret |= *p1++ ^ *p2++;
+ return (ret != 0);
+}
+
+__weak_reference(__timingsafe_bcmp, timingsafe_bcmp);