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ssl: support wildcard matching for verify_subject_alt_name #1298

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3ed769d
ssl: support wildcard matching for verify_subject_alt_name
crazytan Jul 20, 2017
bef14f1
rewrite uriMatch for better performance
crazytan Jul 21, 2017
e4b97c7
change back to using std::string::compare()
crazytan Jul 25, 2017
ad7d440
change back to use strncmp()
crazytan Jul 25, 2017
c878f8b
fix dNSNameMatch and update the doc
crazytan Jul 26, 2017
9347913
cert and config changes for ssl integration tests
crazytan Jul 27, 2017
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4 changes: 3 additions & 1 deletion docs/configuration/cluster_manager/cluster_ssl.rst
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Expand Up @@ -43,7 +43,9 @@ verify_certificate_hash

verify_subject_alt_name
*(optional, array)* An optional list of subject alt names. If specified, Envoy will verify
that the server certificate's subject alt name matches one of the specified values.
that the server certificate's subject alt name matches one of the specified values. The names
support wildcard at the end. For example, ``foo.com/*`` will match certificate with subject alt

@myidpt myidpt Jul 26, 2017

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Could you make it clear that this wildcard support is only for URI type SAN. And also for DNS type SAN, there's a wildcard support for "*.foo.com" style?

name ``foo.com/bar``.

cipher_suites
*(optional, string)* If specified, the TLS connection will only support the specified `cipher list
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4 changes: 3 additions & 1 deletion docs/configuration/listeners/ssl.rst
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Expand Up @@ -65,7 +65,9 @@ verify_certificate_hash

verify_subject_alt_name
*(optional, array)* An optional list of subject alt names. If specified, Envoy will verify
that the client certificate's subject alt name matches one of the specified values.
that the client certificate's subject alt name matches one of the specified values. The names
support wildcard at the end. For example, ``foo.com/*`` will match certificate with subject alt
name ``foo.com/bar``.

cipher_suites
*(optional, string)* If specified, the TLS listener will only support the specified `cipher list
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11 changes: 10 additions & 1 deletion source/common/ssl/context_impl.cc
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Expand Up @@ -209,7 +209,7 @@ bool ContextImpl::verifySubjectAltName(X509* cert,
ASN1_STRING* str = altname->d.uniformResourceIdentifier;
char* crt_san = reinterpret_cast<char*>(ASN1_STRING_data(str));

@PiotrSikora PiotrSikora Jul 26, 2017

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It just occurred to me that there is ASN1_STRING_length(), which is O(1), so this could be changed to:

std::string crt_san(reinterpret_cast<char *>(ASN1_STRING_data(str)), ASN1_STRING_length(str));

and then we could compare strings only if crt_san.length() >= uriPattern.length() and use std::string::compare() again.

Sorry for not catching this yesterday!

@crazytan crazytan Jul 26, 2017

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I'll fix this along with the problem mentioned below.

@crazytan crazytan Jul 26, 2017 •
edited
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a side question though, if we use string (const char* s, size_t n) then isn't it also O(n)? Since the constructor always copies the characters

@mattklein123 mattklein123 Jul 26, 2017

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Yes, that is correct. Optimally, You would just pass char* and length to the function, then still use strncmp (or compare if you can). At this point though let's just get something working that everyone agrees with. :)

@crazytan crazytan Jul 26, 2017

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cool, I'll stick to the current way then

@PiotrSikora PiotrSikora Jul 26, 2017

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...it is. Feel free to ignore this.

Alternatively, you could use ASN1_STRING_length() and pass size_t to do the crt_san_len >= uriPattern.length() check and use std::string::compare().

@crazytan crazytan Jul 26, 2017

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right. I'll pass size_t since it also makes DNS match easier.

for (auto& config_san : subject_alt_names) {
if (config_san.compare(crt_san) == 0) {
if (uriMatch(config_san, crt_san)) {
verified = true;
break;
}
Expand All @@ -223,6 +223,15 @@ bool ContextImpl::verifySubjectAltName(X509* cert,
return verified;
}

bool ContextImpl::uriMatch(const std::string& uriPattern, const char* uri) {

@PiotrSikora PiotrSikora Jul 24, 2017

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This whole function is low-level C instead of C++11.

Please consider using std::string::back() and std::string::compare(0, uriPattern.length() - 1, uri)

@mattklein123 mattklein123 Jul 24, 2017 •
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Yes that would be much better. :)

@crazytan crazytan Jul 24, 2017

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I'm confused but std::string::compare is what I was using. So should I use pointer walk through or string::compare?

@PiotrSikora PiotrSikora Jul 24, 2017

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You should use std::string::back() - O(1), std::string::length() - O(1) and std::string::compare() - O(n).

Previously, you were using strlen() - O(n) and std::string::compare() - O(n), i.e. walking the same string twice, which resulted in suboptimal performance, although the difference is probably negligible.

@crazytan crazytan Jul 25, 2017

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got it. Since my original strlen() was unnecessary, I'll change back to string::compare() to match c++11 style so that future change will be easier.

@myidpt myidpt Jul 26, 2017

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nit: Maybe move this function after dNSNameMatch, to be consistent with the order in the .h file.

size_t pattern_len = uriPattern.length();

@mattklein123 mattklein123 Jul 26, 2017

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nit: const size_t

if (pattern_len > 1 && uriPattern.substr(pattern_len - 2) == "/*") {
return strncmp(uriPattern.c_str(), uri, pattern_len - 1) == 0 && uri[pattern_len - 1];
}

return uriPattern == uri;
}

bool ContextImpl::dNSNameMatch(const std::string& dNSName, const char* pattern) {

@myidpt myidpt Jul 26, 2017

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Sorry to bring this up ... I feel like how this function is called (line 203 in context_impl.cc) is not right. It should be:
dNSNameMatch(dns_name, config_san)
config_san should be the pattern, not dns_name from the cert.

It makes sense to me that we support wildcard in config, not in certificates. Unfortunately I didn't notice this when I modified this function. This was unnoticed because we don't have integration tests, nor did we tell users this wildcard is supported.
@mattklein123 Could you confirm?

@mattklein123 mattklein123 Jul 26, 2017

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@myidpt yes that make sense to me. Can we fix?

@crazytan crazytan Jul 26, 2017 •
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@myidpt @mattklein123 I can fix this and update the doc. So the SAN field, whether it's URI or DNS, should never contain a wildcard; and we allow configs to optionally use wildcard to match multiple SAN values.

@myidpt myidpt Jul 26, 2017

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Thank you very much. Please also make sure the function signature (parameter naming&order) aligns with the uriMatch function :)

if (dNSName == pattern) {
return true;
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8 changes: 8 additions & 0 deletions source/common/ssl/context_impl.h
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Expand Up @@ -68,6 +68,14 @@ class ContextImpl : public virtual Context {
*/
static bool dNSNameMatch(const std::string& dnsName, const char* pattern);

/**
* Determines whether the given URI matches 'pattern' which may end with a wildcard.
* @param uriPattern the pattern to match against
* @param uri the URI to match
* @return true if uri matches pattern
*/
static bool uriMatch(const std::string& uriPattern, const char* uri);

SslStats& stats() { return stats_; }

// Ssl::Context
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20 changes: 20 additions & 0 deletions test/common/ssl/context_impl_test.cc
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Expand Up @@ -30,6 +30,21 @@ TEST_F(SslContextImplTest, TestdNSNameMatching) {
EXPECT_FALSE(ContextImpl::dNSNameMatch("lyft.com", ""));
}

TEST_F(SslContextImplTest, TestURIMatch) {
EXPECT_TRUE(ContextImpl::uriMatch("spiffe://lyft.com/foo", "spiffe://lyft.com/foo"));
EXPECT_TRUE(ContextImpl::uriMatch("spiffe://lyft.com/*", "spiffe://lyft.com/foo"));
EXPECT_TRUE(ContextImpl::uriMatch("spiffe://lyft.com/foo/*", "spiffe://lyft.com/foo/bar"));

@PiotrSikora PiotrSikora Jul 25, 2017

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Could you also add test for:

EXPECT_TRUE(ContextImpl::uriMatch("spiffe://lyft.com/*", "spiffe://lyft.com/foo/bar"));

@crazytan crazytan Jul 25, 2017

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will add

EXPECT_TRUE(ContextImpl::uriMatch("spiffe://lyft.com/*", "spiffe://lyft.com/foo/bar"));
EXPECT_FALSE(ContextImpl::uriMatch("spiffe://lyft.com/*", "spiffe://lyft.com/"));
EXPECT_FALSE(ContextImpl::uriMatch("spiffe://lyft.com/foo", "spiffe://lyft.com/foo/bar"));
EXPECT_FALSE(ContextImpl::uriMatch("spiffe://lyft.com/*", ""));
EXPECT_FALSE(ContextImpl::uriMatch("spiffe://lyft.com/*", "spiffe://lyft.net/foo"));
EXPECT_FALSE(ContextImpl::uriMatch("spiffe://lyft.com*", "spiffe://lyft.com/foo"));
EXPECT_FALSE(ContextImpl::uriMatch("spiffe://lyft.com/*", "spiffe://lyft.comfoo"));
EXPECT_FALSE(ContextImpl::uriMatch("*", "foo"));
EXPECT_FALSE(ContextImpl::uriMatch("f", "foo"));
}

TEST_F(SslContextImplTest, TestVerifySubjectAltNameDNSMatched) {
FILE* fp = fopen(
TestEnvironment::runfilesPath("test/common/ssl/test_data/san_dns_cert.pem").c_str(), "r");
Expand All @@ -52,6 +67,11 @@ TEST_F(SslContextImplTest, TestVerifySubjectAltNameURIMatched) {
std::vector<std::string> verify_subject_alt_name_list = {"spiffe://lyft.com/fake-team",
"spiffe://lyft.com/test-team"};
EXPECT_TRUE(ContextImpl::verifySubjectAltName(cert, verify_subject_alt_name_list));

verify_subject_alt_name_list.clear();
verify_subject_alt_name_list.push_back("spiffe://lyft.com/*");
EXPECT_TRUE(ContextImpl::verifySubjectAltName(cert, verify_subject_alt_name_list));

X509_free(cert);
fclose(fp);
}
Expand Down