decode_msblob2key.c

/*
 * Copyright 2020-2023 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*
 * low level APIs are deprecated for public use, but still ok for
 * internal use.
 */
#include "internal/deprecated.h"

#include <string.h>

#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/core_object.h>
#include <openssl/crypto.h>
#include <openssl/params.h>
#include <openssl/pem.h> /* For public PVK functions */
#include <openssl/x509.h>
#include <openssl/err.h>
#include "internal/passphrase.h"
#include "crypto/pem.h" /* For internal PVK and "blob" headers */
#include "crypto/rsa.h"
#include "prov/bio.h"
#include "prov/implementations.h"
#include "endecoder_local.h"

struct msblob2key_ctx_st; /* Forward declaration */
typedef void *b2i_of_void_fn(const unsigned char **in, unsigned int bitlen,
    int ispub);
typedef void adjust_key_fn(void *, struct msblob2key_ctx_st *ctx);
typedef void free_key_fn(void *);
struct keytype_desc_st {
    int type; /* EVP key type */
    const char *name; /* Keytype */
    const OSSL_DISPATCH *fns; /* Keymgmt (to pilfer functions from) */

    b2i_of_void_fn *read_private_key;
    b2i_of_void_fn *read_public_key;
    adjust_key_fn *adjust_key;
    free_key_fn *free_key;
};

static OSSL_FUNC_decoder_freectx_fn msblob2key_freectx;
static OSSL_FUNC_decoder_decode_fn msblob2key_decode;
static OSSL_FUNC_decoder_export_object_fn msblob2key_export_object;

/*
 * Context used for DER to key decoding.
 */
struct msblob2key_ctx_st {
    PROV_CTX *provctx;
    const struct keytype_desc_st *desc;
    /* The selection that is passed to msblob2key_decode() */
    int selection;
};

static struct msblob2key_ctx_st *
msblob2key_newctx(void *provctx, const struct keytype_desc_st *desc)
{
    struct msblob2key_ctx_st *ctx = OPENSSL_zalloc(sizeof(*ctx));

    if (ctx != NULL) {
        ctx->provctx = provctx;
        ctx->desc = desc;
    }
    return ctx;
}

static void msblob2key_freectx(void *vctx)
{
    struct msblob2key_ctx_st *ctx = vctx;

    OPENSSL_free(ctx);
}

static int msblob2key_does_selection(void *provctx, int selection)
{
    if (selection == 0)
        return 1;

    if ((selection & (OSSL_KEYMGMT_SELECT_PRIVATE_KEY | OSSL_KEYMGMT_SELECT_PUBLIC_KEY)) != 0)
        return 1;

    return 0;
}

static int msblob2key_decode(void *vctx, OSSL_CORE_BIO *cin, int selection,
    OSSL_CALLBACK *data_cb, void *data_cbarg,
    OSSL_PASSPHRASE_CALLBACK *pw_cb, void *pw_cbarg)
{
    struct msblob2key_ctx_st *ctx = vctx;
    BIO *in = ossl_bio_new_from_core_bio(ctx->provctx, cin);
    const unsigned char *p;
    unsigned char hdr_buf[16], *buf = NULL;
    unsigned int bitlen, magic, length;
    int isdss = -1;
    int ispub = -1;
    void *key = NULL;
    int ok = 0;

    if (in == NULL)
        return 0;

    if (BIO_read(in, hdr_buf, 16) != 16) {
        ERR_raise(ERR_LIB_PEM, PEM_R_KEYBLOB_TOO_SHORT);
        goto next;
    }
    ERR_set_mark();
    p = hdr_buf;
    ok = ossl_do_blob_header(&p, 16, &magic, &bitlen, &isdss, &ispub) > 0;
    ERR_pop_to_mark();
    if (!ok)
        goto next;

    ctx->selection = selection;
    ok = 0; /* Assume that we fail */

    if ((isdss && ctx->desc->type != EVP_PKEY_DSA)
        || (!isdss && ctx->desc->type != EVP_PKEY_RSA))
        goto next;

    length = ossl_blob_length(bitlen, isdss, ispub);
    if (length > BLOB_MAX_LENGTH) {
        ERR_raise(ERR_LIB_PEM, PEM_R_HEADER_TOO_LONG);
        goto next;
    }
    buf = OPENSSL_malloc(length);
    if (buf == NULL)
        goto end;
    p = buf;
    if (BIO_read(in, buf, length) != (int)length) {
        ERR_raise(ERR_LIB_PEM, PEM_R_KEYBLOB_TOO_SHORT);
        goto next;
    }

    if ((selection == 0
            || (selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0)
        && !ispub
        && ctx->desc->read_private_key != NULL) {
        struct ossl_passphrase_data_st pwdata;

        memset(&pwdata, 0, sizeof(pwdata));
        if (!ossl_pw_set_ossl_passphrase_cb(&pwdata, pw_cb, pw_cbarg))
            goto end;
        p = buf;
        key = ctx->desc->read_private_key(&p, bitlen, ispub);
        if (selection != 0 && key == NULL)
            goto next;
    }
    if (key == NULL && (selection == 0 || (selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0)
        && ispub
        && ctx->desc->read_public_key != NULL) {
        p = buf;
        key = ctx->desc->read_public_key(&p, bitlen, ispub);
        if (selection != 0 && key == NULL)
            goto next;
    }

    if (key != NULL && ctx->desc->adjust_key != NULL)
        ctx->desc->adjust_key(key, ctx);

next:
    /*
     * Indicated that we successfully decoded something, or not at all.
     * Ending up "empty handed" is not an error.
     */
    ok = 1;

    /*
     * We free resources here so it's not held up during the callback, because
     * we know the process is recursive and the allocated chunks of memory
     * add up.
     */
    OPENSSL_free(buf);
    BIO_free(in);
    buf = NULL;
    in = NULL;

    if (key != NULL) {
        OSSL_PARAM params[4];
        int object_type = OSSL_OBJECT_PKEY;

        params[0] = OSSL_PARAM_construct_int(OSSL_OBJECT_PARAM_TYPE, &object_type);
        params[1] = OSSL_PARAM_construct_utf8_string(OSSL_OBJECT_PARAM_DATA_TYPE,
            (char *)ctx->desc->name, 0);
        /* The address of the key becomes the octet string */
        params[2] = OSSL_PARAM_construct_octet_string(OSSL_OBJECT_PARAM_REFERENCE,
            &key, sizeof(key));
        params[3] = OSSL_PARAM_construct_end();

        ok = data_cb(params, data_cbarg);
    }

end:
    BIO_free(in);
    OPENSSL_free(buf);
    ctx->desc->free_key(key);

    return ok;
}

static int
msblob2key_export_object(void *vctx,
    const void *reference, size_t reference_sz,
    OSSL_CALLBACK *export_cb, void *export_cbarg)
{
    struct msblob2key_ctx_st *ctx = vctx;
    OSSL_FUNC_keymgmt_export_fn *export = ossl_prov_get_keymgmt_export(ctx->desc->fns);
    void *keydata;

    if (reference_sz == sizeof(keydata) && export != NULL) {
        int selection = ctx->selection;

        if (selection == 0)
            selection = OSSL_KEYMGMT_SELECT_ALL;
        /* The contents of the reference is the address to our object */
        keydata = *(void **)reference;

        return export(keydata, selection, export_cb, export_cbarg);
    }
    return 0;
}

/* ---------------------------------------------------------------------- */

#define dsa_decode_private_key (b2i_of_void_fn *)ossl_b2i_DSA_after_header
#define dsa_decode_public_key (b2i_of_void_fn *)ossl_b2i_DSA_after_header
#define dsa_adjust NULL
#define dsa_free (void (*)(void *)) DSA_free

/* ---------------------------------------------------------------------- */

#define rsa_decode_private_key (b2i_of_void_fn *)ossl_b2i_RSA_after_header
#define rsa_decode_public_key (b2i_of_void_fn *)ossl_b2i_RSA_after_header

static void rsa_adjust(void *key, struct msblob2key_ctx_st *ctx)
{
    ossl_rsa_set0_libctx(key, PROV_LIBCTX_OF(ctx->provctx));
}

#define rsa_free (void (*)(void *)) RSA_free

/* ---------------------------------------------------------------------- */

#define IMPLEMENT_MSBLOB(KEYTYPE, keytype)                             \
    static const struct keytype_desc_st mstype##2##keytype##_desc = {  \
        EVP_PKEY_##KEYTYPE, #KEYTYPE,                                  \
        ossl_##keytype##_keymgmt_functions,                            \
        keytype##_decode_private_key,                                  \
        keytype##_decode_public_key,                                   \
        keytype##_adjust,                                              \
        keytype##_free                                                 \
    };                                                                 \
    static OSSL_FUNC_decoder_newctx_fn msblob2##keytype##_newctx;      \
    static void *msblob2##keytype##_newctx(void *provctx)              \
    {                                                                  \
        return msblob2key_newctx(provctx, &mstype##2##keytype##_desc); \
    }                                                                  \
    const OSSL_DISPATCH                                                \
        ossl_msblob_to_##keytype##_decoder_functions[]                 \
        = {                                                            \
              { OSSL_FUNC_DECODER_NEWCTX,                              \
                  (void (*)(void))msblob2##keytype##_newctx },         \
              { OSSL_FUNC_DECODER_FREECTX,                             \
                  (void (*)(void))msblob2key_freectx },                \
              { OSSL_FUNC_DECODER_DOES_SELECTION,                      \
                  (void (*)(void))msblob2key_does_selection },         \
              { OSSL_FUNC_DECODER_DECODE,                              \
                  (void (*)(void))msblob2key_decode },                 \
              { OSSL_FUNC_DECODER_EXPORT_OBJECT,                       \
                  (void (*)(void))msblob2key_export_object },          \
              OSSL_DISPATCH_END                                        \
          }

#ifndef OPENSSL_NO_DSA
IMPLEMENT_MSBLOB(DSA, dsa);
#endif
IMPLEMENT_MSBLOB(RSA, rsa);