Avoid type errors in EAI-related name check logic.

The incorrectly typed data is read only, used in a compare operation, so
neither remote code execution, nor memory content disclosure were possible.
However, applications performing certificate name checks were vulnerable to
denial of service.

The GENERAL_TYPE data type is a union, and we must take care to access the
correct member, based on `gen->type`, not all the member fields have the same
structure, and a segfault is possible if the wrong member field is read.

The code in question was lightly refactored with the intent to make it more
obviously correct.

CVE-2024-6119

(cherry picked from commit 1486960d6cdb052e4fc0109a56a0597b4e902ba1)
This commit is contained in:
Viktor Dukhovni 2024-06-19 21:04:11 +10:00 committed by Gordon Tetlow
parent 1070e7dca8
commit e60dbfd00b
No known key found for this signature in database
GPG Key ID: E5F7BCCBA3BDDDF8
5 changed files with 142 additions and 26 deletions

View File

@ -916,36 +916,64 @@ static int do_x509_check(X509 *x, const char *chk, size_t chklen,
ASN1_STRING *cstr;
gen = sk_GENERAL_NAME_value(gens, i);
if ((gen->type == GEN_OTHERNAME) && (check_type == GEN_EMAIL)) {
if (OBJ_obj2nid(gen->d.otherName->type_id) ==
NID_id_on_SmtpUTF8Mailbox) {
san_present = 1;
/*
* If it is not a UTF8String then that is unexpected and we
* treat it as no match
switch (gen->type) {
default:
continue;
case GEN_OTHERNAME:
switch (OBJ_obj2nid(gen->d.otherName->type_id)) {
default:
continue;
case NID_id_on_SmtpUTF8Mailbox:
/*-
* https://datatracker.ietf.org/doc/html/rfc8398#section-3
*
* Due to name constraint compatibility reasons described
* in Section 6, SmtpUTF8Mailbox subjectAltName MUST NOT
* be used unless the local-part of the email address
* contains non-ASCII characters. When the local-part is
* ASCII, rfc822Name subjectAltName MUST be used instead
* of SmtpUTF8Mailbox. This is compatible with legacy
* software that supports only rfc822Name (and not
* SmtpUTF8Mailbox). [...]
*
* SmtpUTF8Mailbox is encoded as UTF8String.
*
* If it is not a UTF8String then that is unexpected, and
* we ignore the invalid SAN (neither set san_present nor
* consider it a candidate for equality). This does mean
* that the subject CN may be considered, as would be the
* case when the malformed SmtpUtf8Mailbox SAN is instead
* simply absent.
*
* When CN-ID matching is not desirable, applications can
* choose to turn it off, doing so is at this time a best
* practice.
*/
if (gen->d.otherName->value->type == V_ASN1_UTF8STRING) {
cstr = gen->d.otherName->value->value.utf8string;
/* Positive on success, negative on error! */
if ((rv = do_check_string(cstr, 0, equal, flags,
chk, chklen, peername)) != 0)
break;
}
} else
if (check_type != GEN_EMAIL
|| gen->d.otherName->value->type != V_ASN1_UTF8STRING)
continue;
alt_type = 0;
cstr = gen->d.otherName->value->value.utf8string;
break;
}
break;
case GEN_EMAIL:
if (check_type != GEN_EMAIL)
continue;
} else {
if ((gen->type != check_type) && (gen->type != GEN_OTHERNAME))
cstr = gen->d.rfc822Name;
break;
case GEN_DNS:
if (check_type != GEN_DNS)
continue;
cstr = gen->d.dNSName;
break;
case GEN_IPADD:
if (check_type != GEN_IPADD)
continue;
cstr = gen->d.iPAddress;
break;
}
san_present = 1;
if (check_type == GEN_EMAIL)
cstr = gen->d.rfc822Name;
else if (check_type == GEN_DNS)
cstr = gen->d.dNSName;
else
cstr = gen->d.iPAddress;
/* Positive on success, negative on error! */
if ((rv = do_check_string(cstr, alt_type, equal, flags,
chk, chklen, peername)) != 0)

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@ -21,16 +21,18 @@ setup("test_eai_data");
#./util/wrap.pl apps/openssl verify -nameopt utf8 -no_check_time -CAfile test/recipes/25-test_eai_data/utf8_chain.pem test/recipes/25-test_eai_data/ascii_leaf.pem
#./util/wrap.pl apps/openssl verify -nameopt utf8 -no_check_time -CAfile test/recipes/25-test_eai_data/ascii_chain.pem test/recipes/25-test_eai_data/utf8_leaf.pem
plan tests => 12;
plan tests => 16;
require_ok(srctop_file('test','recipes','tconversion.pl'));
my $folder = "test/recipes/25-test_eai_data";
my $ascii_pem = srctop_file($folder, "ascii_leaf.pem");
my $utf8_pem = srctop_file($folder, "utf8_leaf.pem");
my $kdc_pem = srctop_file($folder, "kdc-cert.pem");
my $ascii_chain_pem = srctop_file($folder, "ascii_chain.pem");
my $utf8_chain_pem = srctop_file($folder, "utf8_chain.pem");
my $kdc_chain_pem = srctop_file($folder, "kdc-root-cert.pem");
my $out;
my $outcnt = 0;
@ -56,10 +58,18 @@ SKIP: {
ok(run(app(["openssl", "verify", "-nameopt", "utf8", "-no_check_time", "-CAfile", $ascii_chain_pem, $ascii_pem])));
ok(run(app(["openssl", "verify", "-nameopt", "utf8", "-no_check_time", "-CAfile", $utf8_chain_pem, $utf8_pem])));
ok(run(app(["openssl", "verify", "-nameopt", "utf8", "-no_check_time", "-CAfile", $kdc_chain_pem, $kdc_pem])));
ok(!run(app(["openssl", "verify", "-nameopt", "utf8", "-no_check_time", "-CAfile", $ascii_chain_pem, $utf8_pem])));
ok(!run(app(["openssl", "verify", "-nameopt", "utf8", "-no_check_time", "-CAfile", $utf8_chain_pem, $ascii_pem])));
# Check an otherName does not get misparsed as an DNS name, (should trigger ASAN errors if violated).
ok(run(app(["openssl", "verify", "-nameopt", "utf8", "-no_check_time", "-verify_hostname", 'mx1.example.com', "-CAfile", $kdc_chain_pem, $kdc_pem])));
# Check an otherName does not get misparsed as an email address, (should trigger ASAN errors if violated).
ok(run(app(["openssl", "verify", "-nameopt", "utf8", "-no_check_time", "-verify_email", 'joe@example.com', "-CAfile", $kdc_chain_pem, $kdc_pem])));
# We expect SmtpUTF8Mailbox to be a UTF8 String, not an IA5String.
ok(!run(app(["openssl", "verify", "-nameopt", "utf8", "-no_check_time", "-verify_email", 'moe@example.com', "-CAfile", $kdc_chain_pem, $kdc_pem])));
#Check that we get the expected failure return code
with({ exit_checker => sub { return shift == 2; } },
sub {

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@ -0,0 +1,21 @@
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

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@ -0,0 +1,16 @@
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

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@ -0,0 +1,41 @@
#! /usr/bin/env bash
# Create a root CA, signing a leaf cert with a KDC principal otherName SAN, and
# also a non-UTF8 smtpUtf8Mailbox SAN followed by an rfc822Name SAN and a DNS
# name SAN. In the vulnerable EAI code, the KDC principal `otherName` should
# trigger ASAN errors in DNS name checks, while the non-UTF8 `smtpUtf8Mailbox`
# should likewise lead to ASAN issues with email name checks.
rm -f root-key.pem root-cert.pem
openssl req -nodes -new -newkey rsa:2048 -keyout kdc-root-key.pem \
-x509 -subj /CN=Root -days 36524 -out kdc-root-cert.pem
exts=$(
printf "%s\n%s\n%s\n%s = " \
"subjectKeyIdentifier = hash" \
"authorityKeyIdentifier = keyid" \
"basicConstraints = CA:false" \
"subjectAltName"
printf "%s, " "otherName:1.3.6.1.5.2.2;SEQUENCE:kdc_princ_name"
printf "%s, " "otherName:1.3.6.1.5.5.7.8.9;IA5:moe@example.com"
printf "%s, " "email:joe@example.com"
printf "%s\n" "DNS:mx1.example.com"
printf "[kdc_princ_name]\n"
printf "realm = EXP:0, GeneralString:TEST.EXAMPLE\n"
printf "principal_name = EXP:1, SEQUENCE:kdc_principal_seq\n"
printf "[kdc_principal_seq]\n"
printf "name_type = EXP:0, INTEGER:1\n"
printf "name_string = EXP:1, SEQUENCE:kdc_principal_components\n"
printf "[kdc_principal_components]\n"
printf "princ1 = GeneralString:krbtgt\n"
printf "princ2 = GeneralString:TEST.EXAMPLE\n"
)
printf "%s\n" "$exts"
openssl req -nodes -new -newkey rsa:2048 -keyout kdc-key.pem \
-subj "/CN=TEST.EXAMPLE" |
openssl x509 -req -out kdc-cert.pem \
-CA "kdc-root-cert.pem" -CAkey "kdc-root-key.pem" \
-set_serial 2 -days 36524 \
-extfile <(printf "%s\n" "$exts")