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inspector: harden IP address validation again
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Use inet_pton() to parse IP addresses, which restricts IP addresses
to a small number of well-defined formats. In particular, octal and
hexadecimal number formats are not allowed, and neither are leading
zeros. Also explicitly reject 0.0.0.0/8 and ::/128 as non-routable.

Refs: https://hackerone.com/reports/1710652
CVE-ID: CVE-2022-43548
PR-URL: nodejs-private/node-private#354
Reviewed-by: Michael Dawson <[email protected]>
Reviewed-by: Rafael Gonzaga <[email protected]>
Reviewed-by: Rich Trott <[email protected]>
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@tniessen @RafaelGSS
tniessen authored and RafaelGSS committed Nov 2, 2022
1 parent 6546435 commit 43403f5
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Showing 2 changed files with 141 additions and 16 deletions.
77 changes: 61 additions & 16 deletions src/inspector_socket.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -162,25 +162,70 @@ static std::string TrimPort(const std::string& host) {
}

static bool IsIPAddress(const std::string& host) {
if (host.length() >= 4 && host.front() == '[' && host.back() == ']')
return true;
if (host.front() == '0') return false;
uint_fast16_t accum = 0;
uint_fast8_t quads = 0;
bool empty = true;
auto endOctet = [&accum, &quads, &empty](bool final = false) {
return !empty && accum <= 0xff && ++quads <= 4 && final == (quads == 4) &&
(empty = true) && !(accum = 0);
};
for (char c : host) {
if (isdigit(c)) {
if ((accum = (accum * 10) + (c - '0')) > 0xff) return false;
empty = false;
} else if (c != '.' || !endOctet()) {
// TODO(tniessen): add CVEs to the following bullet points
// To avoid DNS rebinding attacks, we are aware of the following requirements:
// * the host name must be an IP address,
// * the IP address must be routable, and
// * the IP address must be formatted unambiguously.

// The logic below assumes that the string is null-terminated, so ensure that
// we did not somehow end up with null characters within the string.
if (host.find('\0') != std::string::npos) return false;

// All IPv6 addresses must be enclosed in square brackets, and anything
// enclosed in square brackets must be an IPv6 address.
if (host.length() >= 4 && host.front() == '[' && host.back() == ']') {
// INET6_ADDRSTRLEN is the maximum length of the dual format (including the
// terminating null character), which is the longest possible representation
// of an IPv6 address: xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:ddd.ddd.ddd.ddd
if (host.length() - 2 >= INET6_ADDRSTRLEN) return false;

// Annoyingly, libuv's implementation of inet_pton() deviates from other
// implementations of the function in that it allows '%' in IPv6 addresses.
if (host.find('%') != std::string::npos) return false;

// Parse the IPv6 address to ensure it is syntactically valid.
char ipv6_str[INET6_ADDRSTRLEN];
std::copy(host.begin() + 1, host.end() - 1, ipv6_str);
ipv6_str[host.length()] = '\0';
unsigned char ipv6[sizeof(struct in6_addr)];
if (uv_inet_pton(AF_INET6, ipv6_str, ipv6) != 0) return false;

// The only non-routable IPv6 address is ::/128. It should not be necessary
// to explicitly reject it because it will still be enclosed in square
// brackets and not even macOS should make DNS requests in that case, but
// history has taught us that we cannot be careful enough.
// Note that RFC 4291 defines both "IPv4-Compatible IPv6 Addresses" and
// "IPv4-Mapped IPv6 Addresses", which means that there are IPv6 addresses
// (other than ::/128) that represent non-routable IPv4 addresses. However,
// this translation assumes that the host is interpreted as an IPv6 address
// in the first place, at which point DNS rebinding should not be an issue.
if (std::all_of(ipv6, ipv6 + sizeof(ipv6), [](auto b) { return b == 0; })) {
return false;
}

// It is a syntactically valid and routable IPv6 address enclosed in square
// brackets. No client should be able to misinterpret this.
return true;
}
return endOctet(true);

// Anything not enclosed in square brackets must be an IPv4 address. It is
// important here that inet_pton() accepts only the so-called dotted-decimal
// notation, which is a strict subset of the so-called numbers-and-dots
// notation that is allowed by inet_aton() and inet_addr(). This subset does
// not allow hexadecimal or octal number formats.
unsigned char ipv4[sizeof(struct in_addr)];
if (uv_inet_pton(AF_INET, host.c_str(), ipv4) != 0) return false;

// The only strictly non-routable IPv4 address is 0.0.0.0, and macOS will make
// DNS requests for this IP address, so we need to explicitly reject it. In
// fact, we can safely reject all of 0.0.0.0/8 (see Section 3.2 of RFC 791 and
// Section 3.2.1.3 of RFC 1122).
// Note that inet_pton() stores the IPv4 address in network byte order.
if (ipv4[0] == 0) return false;

// It is a routable IPv4 address in dotted-decimal notation.
return true;
}

// Constants for hybi-10 frame format.
Expand Down
80 changes: 80 additions & 0 deletions test/cctest/test_inspector_socket.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -925,6 +925,54 @@ TEST_F(InspectorSocketTest, HostIpTooManyOctetsChecked) {
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIpInvalidOctalOctetStartChecked) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: 08.1.1.1:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIpInvalidOctalOctetMidChecked) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: 1.09.1.1:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIpInvalidOctalOctetEndChecked) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: 1.1.1.009:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIpLeadingZeroStartChecked) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: 01.1.1.1:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIpLeadingZeroMidChecked) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: 1.1.001.1:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIpLeadingZeroEndChecked) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: 1.1.1.01:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIPNonRoutable) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: 0.0.0.0:9229\r\n\r\n";
Expand All @@ -933,4 +981,36 @@ TEST_F(InspectorSocketTest, HostIPNonRoutable) {
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIPv6NonRoutable) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: [::]:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIPv6NonRoutableDual) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: [::0.0.0.0]:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIPv4InSquareBrackets) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: [127.0.0.1]:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

TEST_F(InspectorSocketTest, HostIPv6InvalidAbbreviation) {
const std::string INVALID_HOST_IP_REQUEST = "GET /json HTTP/1.1\r\n"
"Host: [:::1]:9229\r\n\r\n";
send_in_chunks(INVALID_HOST_IP_REQUEST.c_str(),
INVALID_HOST_IP_REQUEST.length());
expect_handshake_failure();
}

} // anonymous namespace

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