backports: add signature verification code

Uh, this was awful. Because the crypto/ things are completely
impossible to backport, I've actually implemented this by using
mbedtls and embedding the relevant functions it has...

The mbedtls code is taken from mbedtls version 2.6.0 and only
minimally modified (mostly to remove <string.h> and similar).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 356 insertions, 0 deletions

diff --git a/backport/compat/verification/mbedtls/md.h b/backport/compat/verification/mbedtls/md.h
new file mode 100644
index 00000000..9385116c
--- /dev/null
+++ b/backport/compat/verification/mbedtls/md.h
@@ -0,0 +1,356 @@
+/**
+ * \file md.h
+ *
+ * \brief Generic message digest wrapper
+ *
+ * \author Adriaan de Jong <dejong@fox-it.com>
+ *
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: GPL-2.0
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+#ifndef MBEDTLS_MD_H
+#define MBEDTLS_MD_H
+
+#include <stddef.h>
+
+#define MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE                -0x5080  /**< The selected feature is not available. */
+#define MBEDTLS_ERR_MD_BAD_INPUT_DATA                     -0x5100  /**< Bad input parameters to function. */
+#define MBEDTLS_ERR_MD_ALLOC_FAILED                       -0x5180  /**< Failed to allocate memory. */
+#define MBEDTLS_ERR_MD_FILE_IO_ERROR                      -0x5200  /**< Opening or reading of file failed. */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum {
+    MBEDTLS_MD_NONE=0,
+    MBEDTLS_MD_MD2,
+    MBEDTLS_MD_MD4,
+    MBEDTLS_MD_MD5,
+    MBEDTLS_MD_SHA1,
+    MBEDTLS_MD_SHA224,
+    MBEDTLS_MD_SHA256,
+    MBEDTLS_MD_SHA384,
+    MBEDTLS_MD_SHA512,
+    MBEDTLS_MD_RIPEMD160,
+} mbedtls_md_type_t;
+
+#if defined(MBEDTLS_SHA512_C)
+#define MBEDTLS_MD_MAX_SIZE         64  /* longest known is SHA512 */
+#else
+#define MBEDTLS_MD_MAX_SIZE         32  /* longest known is SHA256 or less */
+#endif
+
+/**
+ * Opaque struct defined in md_internal.h
+ */
+typedef struct mbedtls_md_info_t mbedtls_md_info_t;
+
+/**
+ * Generic message digest context.
+ */
+typedef struct {
+    /** Information about the associated message digest */
+    const mbedtls_md_info_t *md_info;
+
+    /** Digest-specific context */
+    void *md_ctx;
+
+    /** HMAC part of the context */
+    void *hmac_ctx;
+} mbedtls_md_context_t;
+
+/**
+ * \brief Returns the list of digests supported by the generic digest module.
+ *
+ * \return          a statically allocated array of digests, the last entry
+ *                  is 0.
+ */
+const int *mbedtls_md_list( void );
+
+/**
+ * \brief           Returns the message digest information associated with the
+ *                  given digest name.
+ *
+ * \param md_name   Name of the digest to search for.
+ *
+ * \return          The message digest information associated with md_name or
+ *                  NULL if not found.
+ */
+const mbedtls_md_info_t *mbedtls_md_info_from_string( const char *md_name );
+
+/**
+ * \brief           Returns the message digest information associated with the
+ *                  given digest type.
+ *
+ * \param md_type   type of digest to search for.
+ *
+ * \return          The message digest information associated with md_type or
+ *                  NULL if not found.
+ */
+const mbedtls_md_info_t *mbedtls_md_info_from_type( mbedtls_md_type_t md_type );
+
+/**
+ * \brief           Initialize a md_context (as NONE)
+ *                  This should always be called first.
+ *                  Prepares the context for mbedtls_md_setup() or mbedtls_md_free().
+ */
+void mbedtls_md_init( mbedtls_md_context_t *ctx );
+
+/**
+ * \brief           Free and clear the internal structures of ctx.
+ *                  Can be called at any time after mbedtls_md_init().
+ *                  Mandatory once mbedtls_md_setup() has been called.
+ */
+void mbedtls_md_free( mbedtls_md_context_t *ctx );
+
+#if ! defined(MBEDTLS_DEPRECATED_REMOVED)
+#if defined(MBEDTLS_DEPRECATED_WARNING)
+#define MBEDTLS_DEPRECATED    __attribute__((deprecated))
+#else
+#define MBEDTLS_DEPRECATED
+#endif
+/**
+ * \brief           Select MD to use and allocate internal structures.
+ *                  Should be called after mbedtls_md_init() or mbedtls_md_free().
+ *                  Makes it necessary to call mbedtls_md_free() later.
+ *
+ * \deprecated      Superseded by mbedtls_md_setup() in 2.0.0
+ *
+ * \param ctx       Context to set up.
+ * \param md_info   Message digest to use.
+ *
+ * \returns         \c 0 on success,
+ *                  \c MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter failure,
+ *                  \c MBEDTLS_ERR_MD_ALLOC_FAILED memory allocation failure.
+ */
+int mbedtls_md_init_ctx( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info ) MBEDTLS_DEPRECATED;
+#undef MBEDTLS_DEPRECATED
+#endif /* MBEDTLS_DEPRECATED_REMOVED */
+
+/**
+ * \brief           Select MD to use and allocate internal structures.
+ *                  Should be called after mbedtls_md_init() or mbedtls_md_free().
+ *                  Makes it necessary to call mbedtls_md_free() later.
+ *
+ * \param ctx       Context to set up.
+ * \param md_info   Message digest to use.
+ * \param hmac      0 to save some memory if HMAC will not be used,
+ *                  non-zero is HMAC is going to be used with this context.
+ *
+ * \returns         \c 0 on success,
+ *                  \c MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter failure,
+ *                  \c MBEDTLS_ERR_MD_ALLOC_FAILED memory allocation failure.
+ */
+int mbedtls_md_setup( mbedtls_md_context_t *ctx, const mbedtls_md_info_t *md_info, int hmac );
+
+/**
+ * \brief           Clone the state of an MD context
+ *
+ * \note            The two contexts must have been setup to the same type
+ *                  (cloning from SHA-256 to SHA-512 make no sense).
+ *
+ * \warning         Only clones the MD state, not the HMAC state! (for now)
+ *
+ * \param dst       The destination context
+ * \param src       The context to be cloned
+ *
+ * \return          \c 0 on success,
+ *                  \c MBEDTLS_ERR_MD_BAD_INPUT_DATA on parameter failure.
+ */
+int mbedtls_md_clone( mbedtls_md_context_t *dst,
+                      const mbedtls_md_context_t *src );
+
+/**
+ * \brief           Returns the size of the message digest output.
+ *
+ * \param md_info   message digest info
+ *
+ * \return          size of the message digest output in bytes.
+ */
+unsigned char mbedtls_md_get_size( const mbedtls_md_info_t *md_info );
+
+/**
+ * \brief           Returns the type of the message digest output.
+ *
+ * \param md_info   message digest info
+ *
+ * \return          type of the message digest output.
+ */
+mbedtls_md_type_t mbedtls_md_get_type( const mbedtls_md_info_t *md_info );
+
+/**
+ * \brief           Returns the name of the message digest output.
+ *
+ * \param md_info   message digest info
+ *
+ * \return          name of the message digest output.
+ */
+const char *mbedtls_md_get_name( const mbedtls_md_info_t *md_info );
+
+/**
+ * \brief           Prepare the context to digest a new message.
+ *                  Generally called after mbedtls_md_setup() or mbedtls_md_finish().
+ *                  Followed by mbedtls_md_update().
+ *
+ * \param ctx       generic message digest context.
+ *
+ * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                  verification fails.
+ */
+int mbedtls_md_starts( mbedtls_md_context_t *ctx );
+
+/**
+ * \brief           Generic message digest process buffer
+ *                  Called between mbedtls_md_starts() and mbedtls_md_finish().
+ *                  May be called repeatedly.
+ *
+ * \param ctx       Generic message digest context
+ * \param input     buffer holding the  datal
+ * \param ilen      length of the input data
+ *
+ * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                  verification fails.
+ */
+int mbedtls_md_update( mbedtls_md_context_t *ctx, const unsigned char *input, size_t ilen );
+
+/**
+ * \brief           Generic message digest final digest
+ *                  Called after mbedtls_md_update().
+ *                  Usually followed by mbedtls_md_free() or mbedtls_md_starts().
+ *
+ * \param ctx       Generic message digest context
+ * \param output    Generic message digest checksum result
+ *
+ * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                  verification fails.
+ */
+int mbedtls_md_finish( mbedtls_md_context_t *ctx, unsigned char *output );
+
+/**
+ * \brief          Output = message_digest( input buffer )
+ *
+ * \param md_info  message digest info
+ * \param input    buffer holding the  data
+ * \param ilen     length of the input data
+ * \param output   Generic message digest checksum result
+ *
+ * \returns        0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                 verification fails.
+ */
+int mbedtls_md( const mbedtls_md_info_t *md_info, const unsigned char *input, size_t ilen,
+        unsigned char *output );
+
+#if defined(MBEDTLS_FS_IO)
+/**
+ * \brief          Output = message_digest( file contents )
+ *
+ * \param md_info  message digest info
+ * \param path     input file name
+ * \param output   generic message digest checksum result
+ *
+ * \return         0 if successful,
+ *                 MBEDTLS_ERR_MD_FILE_IO_ERROR if file input failed,
+ *                 MBEDTLS_ERR_MD_BAD_INPUT_DATA if md_info was NULL.
+ */
+int mbedtls_md_file( const mbedtls_md_info_t *md_info, const char *path,
+                     unsigned char *output );
+#endif /* MBEDTLS_FS_IO */
+
+/**
+ * \brief           Set HMAC key and prepare to authenticate a new message.
+ *                  Usually called after mbedtls_md_setup() or mbedtls_md_hmac_finish().
+ *
+ * \param ctx       HMAC context
+ * \param key       HMAC secret key
+ * \param keylen    length of the HMAC key in bytes
+ *
+ * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                  verification fails.
+ */
+int mbedtls_md_hmac_starts( mbedtls_md_context_t *ctx, const unsigned char *key,
+                    size_t keylen );
+
+/**
+ * \brief           Generic HMAC process buffer.
+ *                  Called between mbedtls_md_hmac_starts() or mbedtls_md_hmac_reset()
+ *                  and mbedtls_md_hmac_finish().
+ *                  May be called repeatedly.
+ *
+ * \param ctx       HMAC context
+ * \param input     buffer holding the  data
+ * \param ilen      length of the input data
+ *
+ * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                  verification fails.
+ */
+int mbedtls_md_hmac_update( mbedtls_md_context_t *ctx, const unsigned char *input,
+                    size_t ilen );
+
+/**
+ * \brief           Output HMAC.
+ *                  Called after mbedtls_md_hmac_update().
+ *                  Usually followed by mbedtls_md_hmac_reset(),
+ *                  mbedtls_md_hmac_starts(), or mbedtls_md_free().
+ *
+ * \param ctx       HMAC context
+ * \param output    Generic HMAC checksum result
+ *
+ * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                  verification fails.
+ */
+int mbedtls_md_hmac_finish( mbedtls_md_context_t *ctx, unsigned char *output);
+
+/**
+ * \brief           Prepare to authenticate a new message with the same key.
+ *                  Called after mbedtls_md_hmac_finish() and before
+ *                  mbedtls_md_hmac_update().
+ *
+ * \param ctx       HMAC context to be reset
+ *
+ * \returns         0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                  verification fails.
+ */
+int mbedtls_md_hmac_reset( mbedtls_md_context_t *ctx );
+
+/**
+ * \brief          Output = Generic_HMAC( hmac key, input buffer )
+ *
+ * \param md_info  message digest info
+ * \param key      HMAC secret key
+ * \param keylen   length of the HMAC key in bytes
+ * \param input    buffer holding the  data
+ * \param ilen     length of the input data
+ * \param output   Generic HMAC-result
+ *
+ * \returns        0 on success, MBEDTLS_ERR_MD_BAD_INPUT_DATA if parameter
+ *                 verification fails.
+ */
+int mbedtls_md_hmac( const mbedtls_md_info_t *md_info, const unsigned char *key, size_t keylen,
+                const unsigned char *input, size_t ilen,
+                unsigned char *output );
+
+/* Internal use */
+int mbedtls_md_process( mbedtls_md_context_t *ctx, const unsigned char *data );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MBEDTLS_MD_H */