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Keep only the peer certificate's encoding until it is asked for #12020

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f22107c
Keep only the peer certificate's encoding until it is asked for
LinuxJedi Nov 5, 2026
bbd0042
Name the allocator API's guard where the on-demand test uses it
LinuxJedi Nov 5, 2026
33da09e
Test clearing a connection that kept only the peer encoding
LinuxJedi Nov 5, 2026
cf64cd6
Free the generated Cert only after it was initialized
LinuxJedi Nov 5, 2026
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148 changes: 138 additions & 10 deletions src/internal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6182,6 +6182,7 @@ void FreePeerCert(WOLFSSL* ssl)
wolfSSL_X509_free(ssl->peerCert);
ssl->peerCert = NULL;
}
FreeDer(&ssl->peerCertDer);
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#else
FreeX509(&ssl->peerCert);
InitX509(&ssl->peerCert, 0, ssl->heap);
Expand Down Expand Up @@ -16629,6 +16630,116 @@ int CopyDecodedToX509(WOLFSSL_X509* x509, DecodedCert* dCert)
return ret;
}

#if defined(KEEP_PEER_CERT) && !defined(NO_ASN)
/* Make the certificate in dCert the kept peer certificate, keeping only its
* encoding when the X509 object can be built from it later.
*
* With WOLFSSL_DYNAMIC_PEER_CERT, GetPeerCert() builds the X509 object from
* the encoding on first use, so a connection whose application never asks for
* it does not hold the decoded object, its names and their entries. Otherwise
* the object is filled in now, as by SetPeerCert().
*
* Only for a certificate that was parsed without error, so that decoding it
* again succeeds. Use SetPeerCert() for one accepted despite an error.
*
* @param [in, out] ssl SSL/TLS object.
* @param [in] dCert Decoded peer certificate, with its encoding.
* @return 0 on success.
* @return MEMORY_E when the encoding cannot be stored; no cert is kept.
* @return Other error from SetPeerCert().
*/
int SetPeerCertDer(WOLFSSL* ssl, DecodedCert* dCert)
{
#ifdef WOLFSSL_DYNAMIC_PEER_CERT
if ((dCert->source != NULL) && (dCert->maxIdx > 0)) {
FreePeerCert(ssl);
if (AllocCopyDecodedDer(&ssl->peerCertDer, dCert->source,
dCert->maxIdx, dCert->srcIdx, ssl->heap) != 0) {
return MEMORY_E;
}
return 0;
}
#endif
return SetPeerCert(ssl, dCert);
}

#ifdef WOLFSSL_DYNAMIC_PEER_CERT
/* Build the kept peer certificate object from the kept encoding.
*
* Only the encoding of a certificate that parsed without error is kept, and
* the certificate was verified when it was received, so it is only decoded
* here, as by d2i_X509(). A copy that fails part way is still kept, as by
* SetPeerCert(). When memory runs out the encoding is kept instead, so a
* later call can try again.
*
* @param [in, out] ssl SSL/TLS object with only the encoding kept.
*/
static void BuildPeerCert(WOLFSSL* ssl)
{
int ret = 0;
WOLFSSL_X509* x509 = NULL;
WC_DECLARE_VAR(dCert, DecodedCert, 1, ssl->heap);

WC_ALLOC_VAR_EX(dCert, DecodedCert, 1, ssl->heap, DYNAMIC_TYPE_DCERT,
ret = MEMORY_E);
if (ret == 0) {
InitDecodedCert(dCert, ssl->peerCertDer->buffer,
ssl->peerCertDer->length, ssl->heap);
#if defined(OPENSSL_EXTRA) || defined(OPENSSL_EXTRA_X509_SMALL)
/* CopyDecodedToX509() adds the name entries to the X509 directly. */
dCert->noX509Name = 1;
#endif
ret = ParseCertRelative(dCert, CERT_TYPE, NO_VERIFY, NULL, NULL);
if (ret == 0) {
x509 = wolfSSL_X509_new_ex(ssl->heap);
if (x509 == NULL) {
ret = MEMORY_E;
}
}
if (ret == 0) {
ret = CopyDecodedToX509(x509, dCert);
if (ret == WC_NO_ERR_TRACE(MEMORY_E)) {
wolfSSL_X509_free(x509);
x509 = NULL;
}
}
FreeDecodedCert(dCert);
WC_FREE_VAR_EX(dCert, ssl->heap, DYNAMIC_TYPE_DCERT);
}

if (x509 != NULL) {
/* The object has its own copy of the encoding. */
FreeDer(&ssl->peerCertDer);
ssl->peerCert = x509;
}
else {
WOLFSSL_MSG("Unable to build peer certificate from its encoding");
}
}
#endif /* WOLFSSL_DYNAMIC_PEER_CERT */
#endif /* KEEP_PEER_CERT && !NO_ASN */

#if defined(KEEP_PEER_CERT) && defined(WOLFSSL_DYNAMIC_PEER_CERT)
/* Get the kept peer certificate object.
*
* When only the certificate's encoding is kept, the object is built from it
* now and kept in its place.
*
* @param [in, out] ssl SSL/TLS object.
* @return Kept peer certificate object.
* @return NULL when no certificate is kept or the object cannot be built.
*/
WOLFSSL_X509* GetPeerCert(WOLFSSL* ssl)
{
#ifndef NO_ASN
if ((ssl->peerCert == NULL) && (ssl->peerCertDer != NULL)) {
BuildPeerCert(ssl);
}
#endif
return ssl->peerCert;
}
#endif /* KEEP_PEER_CERT && WOLFSSL_DYNAMIC_PEER_CERT */

#endif /* KEEP_PEER_CERT || SESSION_CERTS */

#if defined(WOLFSSL_ACERT)
Expand Down Expand Up @@ -17247,8 +17358,14 @@ int SetupStoreCtxCallback(WOLFSSL_X509_STORE_CTX** store_pt,
#if defined(OPENSSL_EXTRA) || defined(OPENSSL_EXTRA_X509_SMALL)
#ifdef KEEP_PEER_CERT
if (args->certIdx == 0) {
/* Copy the leaf once, here or in ProcessPeerCerts(). */
if (!args->peerCertSet) {
/* Copy the leaf once, here or in ProcessPeerCerts(). When
* ProcessPeerCerts() kept only its encoding, build the object
* from the decoded leaf rather than decoding it again. */
if (!args->peerCertSet
#ifdef WOLFSSL_DYNAMIC_PEER_CERT
|| ((ssl->peerCert == NULL) && args->dCertInit)
#endif
) {
if (SetPeerCert(ssl, args->dCert) == 0)
args->peerCertSet = 1;
else
Expand Down Expand Up @@ -17993,6 +18110,13 @@ PRAGMA_GCC_DIAG_POP
#endif
/* Parse Certificate */
ret = ParseCertRelative(args->dCert, certType, verify, SSL_CM(ssl), extraSigners);
#ifdef KEEP_PEER_CERT
/* An error here can still be overridden and the leaf accepted, while
* decoding it again later fails the same way. */
if ((certType == CERT_TYPE) && (args->certIdx == 0)) {
args->leafDecodeErr = (ret != 0);
}
#endif
#ifdef WOLFSSL_SMALL_CERT_VERIFY
/* Self signed: the key that verified the signature is its own */
if (verify == VERIFY_NAME && sigRet == 0 && sigCaKey != NULL &&
Expand Down Expand Up @@ -20698,12 +20822,17 @@ int ProcessPeerCerts(WOLFSSL* ssl, byte* input, word32* inOutIdx,

#ifdef KEEP_PEER_CERT
/* The verify callback may have copied the leaf already, on an
* error. Otherwise it is called later and uses this copy. */
* error. Otherwise it is called later and uses what is kept
* here. Only a leaf that parsed without error is kept as its
* encoding alone, as only then can it be decoded again. */
if (args->fatal == 0 && !args->peerCertSet) {
int copyRet = 0;

/* replace old peer cert */
copyRet = SetPeerCert(ssl, args->dCert);
if (args->leafDecodeErr)
copyRet = SetPeerCert(ssl, args->dCert);
else
copyRet = SetPeerCertDer(ssl, args->dCert);
if (copyRet == 0) {
args->peerCertSet = 1;
}
Expand Down Expand Up @@ -45469,13 +45598,12 @@ static int AddPSKtoPreMasterSecret(WOLFSSL* ssl)
if (!ssl->options.dtls) {
const byte* certDer = NULL;
word32 certDerSz = 0;
WOLFSSL_X509* peer = GetPeerCert(ssl);
const DerBuffer* peerDer = GetPeerCertDer(ssl);

if (peer != NULL && peer->derCert != NULL &&
peer->derCert->length > 0) {
if (peerDer != NULL && peerDer->length > 0) {
/* Use current peer certificate */
certDer = peer->derCert->buffer;
certDerSz = peer->derCert->length;
certDer = peerDer->buffer;
certDerSz = peerDer->length;
}
#ifdef SESSION_CERTS
else if (ssl->session->chain.count > 0) {
Expand Down Expand Up @@ -46011,7 +46139,7 @@ static int AddPSKtoPreMasterSecret(WOLFSSL* ssl)
AddSessionCertToChain(&ssl->session->chain,
it->peerCert, peerCertLen);
#endif
ret = SetPeerCert(ssl, dCert);
ret = SetPeerCertDer(ssl, dCert);
if (ret != 0) {
FreePeerCert(ssl);
}
Expand Down
32 changes: 18 additions & 14 deletions src/ssl_api_cert.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2227,12 +2227,12 @@ int wolfSSL_cmp_peer_cert_to_file(WOLFSSL* ssl, const char *fname)
XFILE file = XBADFILE;
long sz = 0;
void* heap = ssl->ctx->heap;
WOLFSSL_X509* peer_cert = GetPeerCert(ssl);
const DerBuffer* peerDer = GetPeerCertDer(ssl);
DerBuffer* fileDer = NULL;

/* handle gracefully if called before handshake, or if peer did not
* present a cert. */
if ((peer_cert == NULL) || (peer_cert->derCert == NULL)) {
if (peerDer == NULL) {
WOLFSSL_MSG("wolfSSL_cmp_peer_cert_to_file without peer cert");
ret = WOLFSSL_FATAL_ERROR;
}
Expand Down Expand Up @@ -2262,8 +2262,8 @@ int wolfSSL_cmp_peer_cert_to_file(WOLFSSL* ssl, const char *fname)
}
/* Peer certificate matches when the DER lengths and bytes are equal. */
if ((ret == 0) && ((fileDer->length == 0) ||
(fileDer->length != peer_cert->derCert->length) ||
(XMEMCMP(peer_cert->derCert->buffer, fileDer->buffer,
(fileDer->length != peerDer->length) ||
(XMEMCMP(peerDer->buffer, fileDer->buffer,
fileDer->length) != 0))) {
ret = WOLFSSL_FATAL_ERROR;
}
Expand Down Expand Up @@ -3055,8 +3055,9 @@ static int DecodeToX509(WOLFSSL_X509* x509, const byte* in, int len)
#ifdef KEEP_PEER_CERT
/* Get the kept peer certificate, owned by the SSL/TLS object.
*
* The certificate is decoded from the session chain, and kept, when not
* already available on the object.
* The certificate is built from its kept encoding on first use. Otherwise it
* is decoded from the session chain, and kept, when not already available on
* the object.
*
* @param [in, out] ssl SSL/TLS object.
* @return Kept peer certificate on success.
Expand Down Expand Up @@ -3215,7 +3216,8 @@ static int PushCAx509Chain(WOLFSSL_CERT_MANAGER* cm,
* certificate, index 0, is taken from the copy kept on the SSL/TLS object
* instead; any other is left out of the stack, as it was before it had a slot.
*
* @param [in] ssl SSL/TLS object.
* @param [in, out] ssl SSL/TLS object. The kept peer certificate may be
* built from its encoding.
* @param [in] idx Index of the certificate in the chain.
* @param [in, out] sk Stack to add the certificate to.
* @param [out] pushed Certificate added to the stack, NULL when the slot
Expand All @@ -3225,7 +3227,7 @@ static int PushCAx509Chain(WOLFSSL_CERT_MANAGER* cm,
* @return Other negative value when the certificate cannot be decoded or
* stored.
*/
static int PushPeerCertToChain(const WOLFSSL* ssl, int idx, WOLFSSL_STACK* sk,
static int PushPeerCertToChain(WOLFSSL* ssl, int idx, WOLFSSL_STACK* sk,
WOLFSSL_X509** pushed)
{
int ret = 0;
Expand All @@ -3235,9 +3237,10 @@ static int PushPeerCertToChain(const WOLFSSL* ssl, int idx, WOLFSSL_STACK* sk,

if (ssl->session->chain.certs[idx].length == 0) {
#ifdef KEEP_PEER_CERT
if ((idx == 0) && (GetPeerCert(ssl) != NULL) &&
(GetPeerCert(ssl)->issuer.sz > 0)) {
x509 = wolfSSL_X509_dup(GetPeerCert(ssl));
WOLFSSL_X509* peer = (idx == 0) ? GetPeerCert(ssl) : NULL;

if ((peer != NULL) && (peer->issuer.sz > 0)) {
x509 = wolfSSL_X509_dup(peer);
if (x509 == NULL) {
WOLFSSL_MSG("Error duplicating peer certificate");
ret = MEMORY_E;
Expand Down Expand Up @@ -3290,13 +3293,14 @@ static int PushPeerCertToChain(const WOLFSSL* ssl, int idx, WOLFSSL_STACK* sk,
* For a verified chain the CA certificates known for the last certificate are
* placed at the bottom of the stack.
*
* @param [in] ssl SSL/TLS object.
* @param [in] verifiedFlag Whether to append the known CA chain.
* @param [in, out] ssl SSL/TLS object. The kept peer certificate
* may be built from its encoding.
* @param [in] verifiedFlag Whether to append the known CA chain.
* @return Stack of the peer's certificates on success.
* @return NULL when ssl is NULL, the session holds no chain, or a certificate
* cannot be created, decoded or stored.
*/
static WOLF_STACK_OF(WOLFSSL_X509)* CreatePeerCertChain(const WOLFSSL* ssl,
static WOLF_STACK_OF(WOLFSSL_X509)* CreatePeerCertChain(WOLFSSL* ssl,
int verifiedFlag)
{
WOLFSSL_STACK* sk = NULL;
Expand Down
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