cda774223d
And update find-doc-nits to complain if "=head1 EXAMPLE" is found. Reviewed-by: Richard Levitte <levitte@openssl.org> Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> (Merged from https://github.com/openssl/openssl/pull/9602)
169 lines
4.9 KiB
Text
169 lines
4.9 KiB
Text
=pod
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=head1 NAME
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OSSL_PARAM_construct_from_text, OSSL_PARAM_allocate_from_text
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- OSSL_PARAM construction utilities
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=head1 SYNOPSIS
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#include <openssl/params.h>
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int OSSL_PARAM_construct_from_text(OSSL_PARAM *to,
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const OSSL_PARAM *paramdefs,
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const char *key, const char *value,
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size_t value_n,
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void *buf, size_t *buf_n)
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int OSSL_PARAM_allocate_from_text(OSSL_PARAM *to,
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const OSSL_PARAM *paramdefs,
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const char *key, const char *value,
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size_t value_n);
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=head1 DESCRIPTION
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With OpenSSL before version 3.0, parameters were passed down to or
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retrieved from algorithm implementations via control functions.
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Some of these control functions existed in variants that took string
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parameters, for example L<EVP_PKEY_CTX_ctrl_str(3)>.
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OpenSSL 3.0 introduces a new mechanism to do the same thing with an
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array of parameters that contain name, value, value type and value
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size (see L<OSSL_PARAM(3)> for more information).
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OSSL_PARAM_construct_from_text() takes a control I<key>, I<value> and
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value size I<value_n>, and given a parameter descriptor array
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I<paramdefs>, it converts the value to something suitable for
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L<OSSL_PARAM(3)> and stores that in the buffer I<buf>, and modifies
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the parameter I<to> to match.
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I<buf_n>, if not NULL, will be assigned the number of bytes used in
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I<buf>.
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If I<buf> is NULL, only I<buf_n> will be modified, everything else is
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left untouched, allowing a caller to find out how large the buffer
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should be.
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I<buf> needs to be correctly aligned for the type of the B<OSSL_PARAM>
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I<key>.
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OSSL_PARAM_allocate_from_text() works like OSSL_PARAM_construct_from_text(),
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except it allocates the buffer internally.
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The caller must remember to free the data of I<to> when it's not
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useful any more.
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For parameters having the type B<OSSL_PARAM_INTEGER>,
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B<OSSL_PARAM_UNSIGNED_INTEGER>, or B<OSSL_PARAM_OCTET_STRING>, both
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functions will interpret the I<value> differently if the key starts
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with "hex".
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In that case, the value is decoded first, and the result will be used
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as parameter value.
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=head1 RETURN VALUES
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OSSL_PARAM_construct_from_text() and OSSL_PARAM_allocate_from_text()
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returns 1 on success, and 0 on error.
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=head1 NOTES
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The parameter descriptor array comes from functions dedicated to
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return them.
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The following B<OSSL_PARAM> attributes are used:
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=over 4
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=item I<key>
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=item I<data>
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=item I<data_size>
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=back
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All other attributes are ignored.
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The I<data_size> attribute can be zero, meaning that the parameter it
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describes expects arbitrary length data.
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=head1 EXAMPLES
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Code that looked like this:
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int mac_ctrl_string(EVP_PKEY_CTX *ctx, const char *value)
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{
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int rv;
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char *stmp, *vtmp = NULL;
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stmp = OPENSSL_strdup(value);
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if (stmp == NULL)
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return -1;
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vtmp = strchr(stmp, ':');
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if (vtmp != NULL)
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*vtmp++ = '\0';
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rv = EVP_MAC_ctrl_str(ctx, stmp, vtmp);
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OPENSSL_free(stmp);
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return rv;
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}
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...
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for (i = 0; i < sk_OPENSSL_STRING_num(macopts); i++) {
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char *macopt = sk_OPENSSL_STRING_value(macopts, i);
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if (pkey_ctrl_string(mac_ctx, macopt) <= 0) {
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BIO_printf(bio_err,
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"MAC parameter error \"%s\"\n", macopt);
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ERR_print_errors(bio_err);
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goto mac_end;
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}
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}
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Can be written like this instead:
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OSSL_PARAM *params =
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OPENSSL_zalloc(sizeof(*params)
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* (sk_OPENSSL_STRING_num(opts) + 1));
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const OSSL_PARAM *paramdefs = EVP_MAC_CTX_settable_params(mac);
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size_t params_n;
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char *opt = "<unknown>";
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for (params_n = 0; params_n < (size_t)sk_OPENSSL_STRING_num(opts);
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params_n++) {
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char *stmp, *vtmp = NULL;
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opt = sk_OPENSSL_STRING_value(opts, (int)params_n);
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if ((stmp = OPENSSL_strdup(opt)) == NULL
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|| (vtmp = strchr(stmp, ':')) == NULL)
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goto err;
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*vtmp++ = '\0';
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if (!OSSL_PARAM_allocate_from_text(¶ms[params_n],
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paramdefs, stmp,
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vtmp, strlen(vtmp)))
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goto err;
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}
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params[params_n] = OSSL_PARAM_construct_end();
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if (!EVP_MAC_CTX_set_params(ctx, params))
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goto err;
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while (params_n-- > 0)
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OPENSSL_free(params[params_n].data);
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OPENSSL_free(params);
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/* ... */
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return;
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err:
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BIO_printf(bio_err, "MAC parameter error '%s'\n", opt);
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ERR_print_errors(bio_err);
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=head1 SEE ALSO
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L<OSSL_PARAM(3)>, L<OSSL_PARAM_TYPE(3)>
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=head1 COPYRIGHT
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Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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