Hello Thomas, I've created a pull request that should clarify the matter: https://github.com/openssl/openssl/pull/22265 Please look there. Tomas Mraz, OpenSSL On Mon, 2023-10-02 at 09:41 +0200, Thomas Bailleux wrote: > Hello OpenSSL, > > I'm currently migrating a codebase from OpenSSL 1.1.1 to OpenSSL 3. > Since I may use OpenSSL providers in the future, I decided to use > these new `_ex` functions from OpenSSL 3. > > While reading the "Old functions that should be changed" from the > migration guide[1], I came across an oddity: it is claimed that in > order to use a non-default library context when parsing an `X509` or > an `EVP_PKEY`, `TYPE_new_ex` must be used (e.g. `X509_new_ex`), and > then we have to use the "reuse" capability from the various parsing > functions (`PEM_read_bio_X509`): > > > Some functions can be passed an object that has already been set up > > with a library context such as d2i_X509(3), d2i_X509_CRL(3), > > d2i_X509_REQ(3) and d2i_X509_PUBKEY(3). If NULL is passed instead > > then the created object will be set up with the default library > > context. Use X509_new_ex(3), X509_CRL_new_ex(3), X509_REQ_new_ex(3) > > and X509_PUBKEY_new_ex(3) if a library context is required. > > So basically we have to do the following: > > > BIO *bio; > > OSSL_LIB_CTX* lib_ctx; > > X509 *x509 = X509_new_ex(lib_ctx, NULL); > > if (d2i_X509_bio(bio, &x509) != NULL) { > > // success > > } else { > > // error > > } > > > > > However, in the `D2I_X509` manpage[2], the following is stated: > > > On a successful return, if *a is not NULL then it is assumed that > > *a contains a valid TYPE structure and an attempt is made to reuse > > it. This "reuse" capability is present for historical compatibility > > but its use is strongly discouraged (see BUGS below, and the > > discussion in the RETURN VALUES section). > > … > > BUGS > > … > > As a result of the above issues the "reuse" behaviour is strongly > > discouraged. > > > > So if I'm understanding correctly, this "reuse" capability is > discouraged, still present for historical compatibility, but in > OpenSSL 3 we have to use it if we want to use a custom library > context. > > This divergence between these two bits of documentation bothers me. > Do you have an opinion on this? > > Regards, > > - thomas > > > [1]: > https://www.openssl.org/docs/man3.1/man7/migration_guide.html#Using-a-Library-Context---Old-functions-that-should-be-changed > [2]: https://www.openssl.org/docs/man3.1/man3/d2i_X509.html -- Tomáš Mráz, OpenSSL
