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authorBernhard Schmidt <berni@debian.org>2020-08-15 21:29:50 +0200
committerBernhard Schmidt <berni@debian.org>2020-08-15 21:29:50 +0200
commit1079962e4c06f88a54e50d997c1b7e84303d30b4 (patch)
tree4d019426928435425214ccedd6f89b70dbdf035d /src/openvpn/crypto_mbedtls.c
parent620785fe268a1221c1ba7a9cb5a70f3140a4f1ca (diff)
New upstream version 2.5~beta1upstream/2.5_beta1
Diffstat (limited to 'src/openvpn/crypto_mbedtls.c')
-rw-r--r--src/openvpn/crypto_mbedtls.c173
1 files changed, 129 insertions, 44 deletions
diff --git a/src/openvpn/crypto_mbedtls.c b/src/openvpn/crypto_mbedtls.c
index 748043e..fbb1f12 100644
--- a/src/openvpn/crypto_mbedtls.c
+++ b/src/openvpn/crypto_mbedtls.c
@@ -34,21 +34,24 @@
#include "syshead.h"
-#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS)
+#if defined(ENABLE_CRYPTO_MBEDTLS)
#include "errlevel.h"
#include "basic.h"
#include "buffer.h"
+#include "crypto.h"
#include "integer.h"
#include "crypto_backend.h"
#include "otime.h"
#include "misc.h"
+#include <mbedtls/base64.h>
#include <mbedtls/des.h>
#include <mbedtls/error.h>
#include <mbedtls/md5.h>
#include <mbedtls/cipher.h>
#include <mbedtls/havege.h>
+#include <mbedtls/pem.h>
#include <mbedtls/entropy.h>
@@ -138,26 +141,6 @@ const cipher_name_pair cipher_name_translation_table[] = {
const size_t cipher_name_translation_table_count =
sizeof(cipher_name_translation_table) / sizeof(*cipher_name_translation_table);
-static void
-print_cipher(const cipher_kt_t *info)
-{
- if (info && (cipher_kt_mode_cbc(info)
-#ifdef HAVE_AEAD_CIPHER_MODES
- || cipher_kt_mode_aead(info)
-#endif
- ))
- {
- const char *ssl_only = cipher_kt_mode_cbc(info) ?
- "" : ", TLS client/server mode only";
- const char *var_key_size = info->flags & MBEDTLS_CIPHER_VARIABLE_KEY_LEN ?
- " by default" : "";
-
- printf("%s (%d bit key%s, %d bit block%s)\n",
- cipher_kt_name(info), cipher_kt_key_size(info) * 8, var_key_size,
- cipher_kt_block_size(info) * 8, ssl_only);
- }
-}
-
void
show_available_ciphers(void)
{
@@ -166,14 +149,16 @@ show_available_ciphers(void)
#ifndef ENABLE_SMALL
printf("The following ciphers and cipher modes are available for use\n"
"with " PACKAGE_NAME ". Each cipher shown below may be used as a\n"
- "parameter to the --cipher option. Using a CBC or GCM mode is\n"
- "recommended. In static key mode only CBC mode is allowed.\n\n");
+ "parameter to the --data-ciphers (or --cipher) option. Using a\n"
+ "GCM or CBC mode is recommended. In static key mode only CBC\n"
+ "mode is allowed.\n\n");
#endif
while (*ciphers != 0)
{
const cipher_kt_t *info = mbedtls_cipher_info_from_type(*ciphers);
- if (info && cipher_kt_block_size(info) >= 128/8)
+ if (info && !cipher_kt_insecure(info)
+ && (cipher_kt_mode_aead(info) || cipher_kt_mode_cbc(info)))
{
print_cipher(info);
}
@@ -186,7 +171,8 @@ show_available_ciphers(void)
while (*ciphers != 0)
{
const cipher_kt_t *info = mbedtls_cipher_info_from_type(*ciphers);
- if (info && cipher_kt_block_size(info) < 128/8)
+ if (info && cipher_kt_insecure(info)
+ && (cipher_kt_mode_aead(info) || cipher_kt_mode_cbc(info)))
{
print_cipher(info);
}
@@ -229,6 +215,84 @@ show_available_engines(void)
"available\n");
}
+bool
+crypto_pem_encode(const char *name, struct buffer *dst,
+ const struct buffer *src, struct gc_arena *gc)
+{
+ /* 1000 chars is the PEM line length limit (+1 for tailing NUL) */
+ char header[1000+1] = { 0 };
+ char footer[1000+1] = { 0 };
+
+ if (!openvpn_snprintf(header, sizeof(header), "-----BEGIN %s-----\n", name))
+ {
+ return false;
+ }
+ if (!openvpn_snprintf(footer, sizeof(footer), "-----END %s-----\n", name))
+ {
+ return false;
+ }
+
+ size_t out_len = 0;
+ if (MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL !=
+ mbedtls_pem_write_buffer(header, footer, BPTR(src), BLEN(src),
+ NULL, 0, &out_len))
+ {
+ return false;
+ }
+
+ /* We set the size buf to out_len-1 to NOT include the 0 byte that
+ * mbedtls_pem_write_buffer in its length calculation */
+ *dst = alloc_buf_gc(out_len, gc);
+ if (!mbed_ok(mbedtls_pem_write_buffer(header, footer, BPTR(src), BLEN(src),
+ BPTR(dst), BCAP(dst), &out_len))
+ || !buf_inc_len(dst, out_len-1))
+ {
+ CLEAR(*dst);
+ return false;
+ }
+
+ return true;
+}
+
+bool
+crypto_pem_decode(const char *name, struct buffer *dst,
+ const struct buffer *src)
+{
+ /* 1000 chars is the PEM line length limit (+1 for tailing NUL) */
+ char header[1000+1] = { 0 };
+ char footer[1000+1] = { 0 };
+
+ if (!openvpn_snprintf(header, sizeof(header), "-----BEGIN %s-----", name))
+ {
+ return false;
+ }
+ if (!openvpn_snprintf(footer, sizeof(footer), "-----END %s-----", name))
+ {
+ return false;
+ }
+
+ /* mbed TLS requires the src to be null-terminated */
+ /* allocate a new buffer to avoid modifying the src buffer */
+ struct gc_arena gc = gc_new();
+ struct buffer input = alloc_buf_gc(BLEN(src) + 1, &gc);
+ buf_copy(&input, src);
+ buf_null_terminate(&input);
+
+ size_t use_len = 0;
+ mbedtls_pem_context ctx = { 0 };
+ bool ret = mbed_ok(mbedtls_pem_read_buffer(&ctx, header, footer, BPTR(&input),
+ NULL, 0, &use_len));
+ if (ret && !buf_write(dst, ctx.buf, ctx.buflen))
+ {
+ ret = false;
+ msg(M_WARN, "PEM decode error: destination buffer too small");
+ }
+
+ mbedtls_pem_free(&ctx);
+ gc_free(&gc);
+ return ret;
+}
+
/*
*
* Random number functions, used in cases where we want
@@ -402,6 +466,7 @@ cipher_kt_get(const char *ciphername)
ASSERT(ciphername);
+ ciphername = translate_cipher_name_from_openvpn(ciphername);
cipher = mbedtls_cipher_info_from_string(ciphername);
if (NULL == cipher)
@@ -466,15 +531,23 @@ cipher_kt_block_size(const mbedtls_cipher_info_t *cipher_kt)
int
cipher_kt_tag_size(const mbedtls_cipher_info_t *cipher_kt)
{
-#ifdef HAVE_AEAD_CIPHER_MODES
if (cipher_kt && cipher_kt_mode_aead(cipher_kt))
{
return OPENVPN_AEAD_TAG_LENGTH;
}
-#endif
return 0;
}
+bool
+cipher_kt_insecure(const mbedtls_cipher_info_t *cipher_kt)
+{
+ return !(cipher_kt_block_size(cipher_kt) >= 128 / 8
+#ifdef MBEDTLS_CHACHAPOLY_C
+ || cipher_kt->type == MBEDTLS_CIPHER_CHACHA20_POLY1305
+#endif
+ );
+}
+
int
cipher_kt_mode(const mbedtls_cipher_info_t *cipher_kt)
{
@@ -498,7 +571,11 @@ cipher_kt_mode_ofb_cfb(const cipher_kt_t *cipher)
bool
cipher_kt_mode_aead(const cipher_kt_t *cipher)
{
- return cipher && cipher_kt_mode(cipher) == OPENVPN_MODE_GCM;
+ return cipher && (cipher_kt_mode(cipher) == OPENVPN_MODE_GCM
+#ifdef MBEDTLS_CHACHAPOLY_C
+ || cipher_kt_mode(cipher) == MBEDTLS_MODE_CHACHAPOLY
+#endif
+ );
}
@@ -554,7 +631,6 @@ cipher_ctx_iv_length(const mbedtls_cipher_context_t *ctx)
int
cipher_ctx_get_tag(cipher_ctx_t *ctx, uint8_t *tag, int tag_len)
{
-#ifdef HAVE_AEAD_CIPHER_MODES
if (tag_len > SIZE_MAX)
{
return 0;
@@ -566,9 +642,6 @@ cipher_ctx_get_tag(cipher_ctx_t *ctx, uint8_t *tag, int tag_len)
}
return 1;
-#else /* ifdef HAVE_AEAD_CIPHER_MODES */
- ASSERT(0);
-#endif /* HAVE_AEAD_CIPHER_MODES */
}
int
@@ -592,7 +665,7 @@ cipher_ctx_get_cipher_kt(const cipher_ctx_t *ctx)
}
int
-cipher_ctx_reset(mbedtls_cipher_context_t *ctx, uint8_t *iv_buf)
+cipher_ctx_reset(mbedtls_cipher_context_t *ctx, const uint8_t *iv_buf)
{
if (!mbed_ok(mbedtls_cipher_reset(ctx)))
{
@@ -610,7 +683,6 @@ cipher_ctx_reset(mbedtls_cipher_context_t *ctx, uint8_t *iv_buf)
int
cipher_ctx_update_ad(cipher_ctx_t *ctx, const uint8_t *src, int src_len)
{
-#ifdef HAVE_AEAD_CIPHER_MODES
if (src_len > SIZE_MAX)
{
return 0;
@@ -622,9 +694,6 @@ cipher_ctx_update_ad(cipher_ctx_t *ctx, const uint8_t *src, int src_len)
}
return 1;
-#else /* ifdef HAVE_AEAD_CIPHER_MODES */
- ASSERT(0);
-#endif /* HAVE_AEAD_CIPHER_MODES */
}
int
@@ -663,7 +732,6 @@ int
cipher_ctx_final_check_tag(mbedtls_cipher_context_t *ctx, uint8_t *dst,
int *dst_len, uint8_t *tag, size_t tag_len)
{
-#ifdef HAVE_AEAD_CIPHER_MODES
size_t olen = 0;
if (MBEDTLS_DECRYPT != ctx->operation)
@@ -695,9 +763,6 @@ cipher_ctx_final_check_tag(mbedtls_cipher_context_t *ctx, uint8_t *dst,
}
return 1;
-#else /* ifdef HAVE_AEAD_CIPHER_MODES */
- ASSERT(0);
-#endif /* HAVE_AEAD_CIPHER_MODES */
}
void
@@ -751,7 +816,7 @@ md_kt_name(const mbedtls_md_info_t *kt)
return mbedtls_md_get_name(kt);
}
-int
+unsigned char
md_kt_size(const mbedtls_md_info_t *kt)
{
if (NULL == kt)
@@ -781,7 +846,8 @@ md_ctx_new(void)
return ctx;
}
-void md_ctx_free(mbedtls_md_context_t *ctx)
+void
+md_ctx_free(mbedtls_md_context_t *ctx)
{
free(ctx);
}
@@ -899,4 +965,23 @@ hmac_ctx_final(mbedtls_md_context_t *ctx, uint8_t *dst)
ASSERT(0 == mbedtls_md_hmac_finish(ctx, dst));
}
-#endif /* ENABLE_CRYPTO && ENABLE_CRYPTO_MBEDTLS */
+int
+memcmp_constant_time(const void *a, const void *b, size_t size)
+{
+ /* mbed TLS has a no const time memcmp function that it exposes
+ * via its APIs like OpenSSL does with CRYPTO_memcmp
+ * Adapt the function that mbedtls itself uses in
+ * mbedtls_safer_memcmp as it considers that to be safe */
+ volatile const unsigned char *A = (volatile const unsigned char *) a;
+ volatile const unsigned char *B = (volatile const unsigned char *) b;
+ volatile unsigned char diff = 0;
+
+ for (size_t i = 0; i < size; i++)
+ {
+ unsigned char x = A[i], y = B[i];
+ diff |= x ^ y;
+ }
+
+ return diff;
+}
+#endif /* ENABLE_CRYPTO_MBEDTLS */