openssl/doc/man3/X509_STORE_get0_param.pod
David Benjamin 08cecb4448 Add X509_STORE_get1_objects
X509_STORE_get0_objects returns a pointer to the X509_STORE's storage,
but this function is a bit deceptive. It is practically unusable in a
multi-threaded program. See, for example, RUSTSEC-2023-0072, a security
vulnerability caused by this OpenSSL API.

One might think that, if no other threads are mutating the X509_STORE,
it is safe to read the resulting list. However, the documention does not
mention that other logically-const operations on the X509_STORE, notably
certifcate verifications when a hash_dir is installed, will, under a
lock, write to the X509_STORE. The X509_STORE also internally re-sorts
the list on the first query.

If the caller knows to call X509_STORE_lock and X509_STORE_unlock, it
can work around this. But this is not obvious, and the documentation
does not discuss how X509_STORE_lock is very rarely safe to use. E.g.
one cannot call any APIs like X509_STORE_add_cert or
X509_STORE_CTX_get1_issuer while holding the lock because those
functions internally expect to take the lock. (X509_STORE_lock is
another such API which is not safe to export as public API.)

Rather than leave all this to the caller to figure out, the API should
have returned a shallow copy of the list, refcounting the values. Then
it could be internally locked and the caller can freely inspect the
result without synchronization with the X509_STORE.

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23224)
2024-01-15 16:29:54 +01:00

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=pod
=head1 NAME
X509_STORE_get0_param, X509_STORE_set1_param,
X509_STORE_get1_objects, X509_STORE_get0_objects, X509_STORE_get1_all_certs
- X509_STORE setter and getter functions
=head1 SYNOPSIS
#include <openssl/x509_vfy.h>
X509_VERIFY_PARAM *X509_STORE_get0_param(const X509_STORE *xs);
int X509_STORE_set1_param(X509_STORE *xs, const X509_VERIFY_PARAM *pm);
STACK_OF(X509_OBJECT) *X509_STORE_get1_objects(X509_STORE *xs);
STACK_OF(X509_OBJECT) *X509_STORE_get0_objects(const X509_STORE *xs);
STACK_OF(X509) *X509_STORE_get1_all_certs(X509_STORE *xs);
=head1 DESCRIPTION
X509_STORE_set1_param() sets the verification parameters to I<pm> for I<xs>.
X509_STORE_get0_param() retrieves an internal pointer to the verification
parameters for I<xs>. The returned pointer must not be freed by the
calling application
X509_STORE_get1_objects() returns a snapshot of all objects in the store's X509
cache. The cache contains B<X509> and B<X509_CRL> objects. The caller is
responsible for freeing the returned list.
X509_STORE_get0_objects() retrieves an internal pointer to the store's
X509 object cache. The cache contains B<X509> and B<X509_CRL> objects. The
returned pointer must not be freed by the calling application. If the store is
shared across multiple threads, it is not safe to use the result of this
function. Use X509_STORE_get1_objects() instead, which avoids this problem.
X509_STORE_get1_all_certs() returns a list of all certificates in the store.
The caller is responsible for freeing the returned list.
=head1 RETURN VALUES
X509_STORE_get0_param() returns a pointer to an
B<X509_VERIFY_PARAM> structure.
X509_STORE_set1_param() returns 1 for success and 0 for failure.
X509_STORE_get1_objects() returns a pointer to a stack of the retrieved
objects on success, else NULL.
X509_STORE_get0_objects() returns a pointer to a stack of B<X509_OBJECT>.
X509_STORE_get1_all_certs() returns a pointer to a stack of the retrieved
certificates on success, else NULL.
=head1 SEE ALSO
L<X509_STORE_new(3)>
=head1 HISTORY
B<X509_STORE_get0_param> and B<X509_STORE_get0_objects> were added in
OpenSSL 1.1.0.
B<X509_STORE_get1_certs> was added in OpenSSL 3.0.
B<X509_STORE_get1_objects> was added in OpenSSL 3.3.
=head1 COPYRIGHT
Copyright 2016-2020 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
L<https://www.openssl.org/source/license.html>.
=cut