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Add entire issuer chain to trusted X509_STORE when stapling OCSP_Resp…
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…onse (dotnet#96792)

* Add entire issuer chain to trusted X509_STORE when validating OCSP_Response

* Code review feedback

* More code review feedback

* Update src/libraries/System.Net.Security/src/System/Net/Security/SslStreamCertificateContext.Linux.cs

Co-authored-by: Jeremy Barton <jbarton@microsoft.com>

* Fix compilation

* Always include root certificate

---------

Co-authored-by: Jeremy Barton <jbarton@microsoft.com>
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@rzikm @bartonjs
rzikm and bartonjs committed Jan 11, 2024
1 parent 39c885c commit a6bf4e4
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Showing 4 changed files with 56 additions and 21 deletions.
9 changes: 6 additions & 3 deletions src/libraries/Common/src/Interop/Unix/System.Security.Cryptography.Native/Interop.OCSP.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,27 +29,30 @@ private static unsafe partial int CryptoNative_X509DecodeOcspToExpiration(
int len,
SafeOcspRequestHandle req,
IntPtr subject,
IntPtr issuer,
IntPtr* issuers,
int issuersLen,
ref long expiration);

internal static unsafe bool X509DecodeOcspToExpiration(
ReadOnlySpan<byte> buf,
SafeOcspRequestHandle request,
IntPtr x509Subject,
IntPtr x509Issuer,
ReadOnlySpan<IntPtr> x509Issuers,
out DateTimeOffset expiration)
{
long timeT = 0;
int ret;

fixed (byte* pBuf = buf)
fixed (IntPtr* pIssuers = x509Issuers)
{
ret = CryptoNative_X509DecodeOcspToExpiration(
pBuf,
buf.Length,
request,
x509Subject,
x509Issuer,
pIssuers,
x509Issuers.Length,
ref timeT);
}

Expand Down
49 changes: 36 additions & 13 deletions ...ibraries/System.Net.Security/src/System/Net/Security/SslStreamCertificateContext.Linux.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,13 +26,30 @@ public partial class SslStreamCertificateContext
private byte[]? _ocspResponse;
private DateTimeOffset _ocspExpiration;
private DateTimeOffset _nextDownload;
// Private copy of the intermediate certificates, in case the user decides to dispose the
// instances reachable through IntermediateCertificates property.
private X509Certificate2[] _privateIntermediateCertificates;
private X509Certificate2? _rootCertificate;
private Task<byte[]?>? _pendingDownload;
private List<string>? _ocspUrls;
private X509Certificate2? _ca;

private SslStreamCertificateContext(X509Certificate2 target, ReadOnlyCollection<X509Certificate2> intermediates, SslCertificateTrust? trust)
{
IntermediateCertificates = intermediates;
if (intermediates.Count > 0)
{
_privateIntermediateCertificates = new X509Certificate2[intermediates.Count];

for (int i = 0; i < intermediates.Count; i++)
{
_privateIntermediateCertificates[i] = new X509Certificate2(intermediates[i]);
}
}
else
{
_privateIntermediateCertificates = Array.Empty<X509Certificate2>();
}

TargetCertificate = target;
Trust = trust;
SslContexts = new ConcurrentDictionary<SslProtocols, SafeSslContextHandle>();
Expand Down Expand Up @@ -76,15 +93,8 @@ partial void SetNoOcspFetch(bool noOcspFetch)

partial void AddRootCertificate(X509Certificate2? rootCertificate, ref bool transferredOwnership)
{
if (IntermediateCertificates.Count == 0)
{
_ca = rootCertificate;
transferredOwnership = true;
}
else
{
_ca = IntermediateCertificates[0];
}
_rootCertificate = rootCertificate;
transferredOwnership = rootCertificate != null;

if (!_staplingForbidden)
{
Expand Down Expand Up @@ -149,7 +159,7 @@ partial void AddRootCertificate(X509Certificate2? rootCertificate, ref bool tran
return new ValueTask<byte[]?>(pending);
}

if (_ocspUrls is null && _ca is not null)
if (_ocspUrls is null && _rootCertificate is not null)
{
foreach (X509Extension ext in TargetCertificate.Extensions)
{
Expand Down Expand Up @@ -192,7 +202,9 @@ partial void AddRootCertificate(X509Certificate2? rootCertificate, ref bool tran

private async Task<byte[]?> FetchOcspAsync()
{
X509Certificate2? caCert = _ca;
Debug.Assert(_rootCertificate != null);
X509Certificate2? caCert = _privateIntermediateCertificates.Length > 0 ? _privateIntermediateCertificates[0] : _rootCertificate;

Debug.Assert(_ocspUrls is not null);
Debug.Assert(_ocspUrls.Count > 0);
Debug.Assert(caCert is not null);
Expand All @@ -211,6 +223,13 @@ partial void AddRootCertificate(X509Certificate2? rootCertificate, ref bool tran
return null;
}

IntPtr[] issuerHandles = ArrayPool<IntPtr>.Shared.Rent(_privateIntermediateCertificates.Length + 1);
for (int i = 0; i < _privateIntermediateCertificates.Length; i++)
{
issuerHandles[i] = _privateIntermediateCertificates[i].Handle;
}
issuerHandles[_privateIntermediateCertificates.Length] = _rootCertificate.Handle;

using (SafeOcspRequestHandle ocspRequest = Interop.Crypto.X509BuildOcspRequest(subject, issuer))
{
byte[] rentedBytes = ArrayPool<byte>.Shared.Rent(Interop.Crypto.GetOcspRequestDerSize(ocspRequest));
Expand All @@ -227,7 +246,7 @@ partial void AddRootCertificate(X509Certificate2? rootCertificate, ref bool tran

if (ret is not null)
{
if (!Interop.Crypto.X509DecodeOcspToExpiration(ret, ocspRequest, subject, issuer, out DateTimeOffset expiration))
if (!Interop.Crypto.X509DecodeOcspToExpiration(ret, ocspRequest, subject, issuerHandles.AsSpan(0, _privateIntermediateCertificates.Length + 1), out DateTimeOffset expiration))
{
ret = null;
continue;
Expand All @@ -251,9 +270,13 @@ partial void AddRootCertificate(X509Certificate2? rootCertificate, ref bool tran
}
}

issuerHandles.AsSpan().Clear();
ArrayPool<IntPtr>.Shared.Return(issuerHandles);
ArrayPool<byte>.Shared.Return(rentedBytes);
ArrayPool<char>.Shared.Return(rentedChars.Array!);
GC.KeepAlive(TargetCertificate);
GC.KeepAlive(_privateIntermediateCertificates);
GC.KeepAlive(_rootCertificate);
GC.KeepAlive(caCert);

_pendingDownload = null;
Expand Down
17 changes: 13 additions & 4 deletions src/native/libs/System.Security.Cryptography.Native/pal_x509.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1302,11 +1302,11 @@ CryptoNative_X509ChainVerifyOcsp(X509_STORE_CTX* storeCtx, OCSP_REQUEST* req, OC
return X509ChainVerifyOcsp(storeCtx, subject, issuer, req, resp, cachePath);
}

int32_t CryptoNative_X509DecodeOcspToExpiration(const uint8_t* buf, int32_t len, OCSP_REQUEST* req, X509* subject, X509* issuer, int64_t* expiration)
int32_t CryptoNative_X509DecodeOcspToExpiration(const uint8_t* buf, int32_t len, OCSP_REQUEST* req, X509* subject, X509** issuers, int issuersLen, int64_t* expiration)
{
ERR_clear_error();

if (buf == NULL || len == 0)
if (buf == NULL || len == 0 || issuersLen == 0)
{
return 0;
}
Expand All @@ -1329,7 +1329,16 @@ int32_t CryptoNative_X509DecodeOcspToExpiration(const uint8_t* buf, int32_t len,

if (bag != NULL)
{
if (X509_STORE_add_cert(store, issuer) && sk_X509_push(bag, issuer))
int i;
for (i = 0; i < issuersLen; i++)
{
if (!X509_STORE_add_cert(store, issuers[i]) || !sk_X509_push(bag, issuers[i]))
{
break;
}
}

if (i == issuersLen)
{
ctx = X509_STORE_CTX_new();
}
Expand All @@ -1343,7 +1352,7 @@ int32_t CryptoNative_X509DecodeOcspToExpiration(const uint8_t* buf, int32_t len,
{
int canCache = 0;
time_t expiration_t = 0;
X509VerifyStatusCode code = CheckOcspGetExpiry(req, resp, subject, issuer, ctx, &canCache, &expiration_t);
X509VerifyStatusCode code = CheckOcspGetExpiry(req, resp, subject, issuers[0], ctx, &canCache, &expiration_t);

if (sizeof(time_t) == sizeof(int64_t))
{
Expand Down
2 changes: 1 addition & 1 deletion src/native/libs/System.Security.Cryptography.Native/pal_x509.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -412,4 +412,4 @@ PALEXPORT int32_t CryptoNative_X509ChainVerifyOcsp(X509_STORE_CTX* storeCtx,
Decode len bytes of buf into an OCSP response, process it against the OCSP request, and return if the bytes were valid.
If the bytes were valid, and the OCSP response had a nextUpdate value, assign it to expiration.
*/
PALEXPORT int32_t CryptoNative_X509DecodeOcspToExpiration(const uint8_t* buf, int32_t len, OCSP_REQUEST* req, X509* subject, X509* issuer, int64_t* expiration);
PALEXPORT int32_t CryptoNative_X509DecodeOcspToExpiration(const uint8_t* buf, int32_t len, OCSP_REQUEST* req, X509* subject, X509** issuers, int issuersLen, int64_t* expiration);

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