/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* tests/gssapi/t_invalid.c - Invalid message token regression tests */
/*
* Copyright (C) 2014 by the Massachusetts Institute of Technology.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This file contains regression tests for some GSSAPI invalid token
* vulnerabilities.
*
* 1. A pre-CFX wrap or MIC token processed with a CFX-only context causes a
* null pointer dereference. (The token must use SEAL_ALG_NONE or it will
* be rejected.)
*
* 2. A pre-CFX wrap or MIC token with fewer than 24 bytes after the ASN.1
* header causes an input buffer overrun, usually leading to either a segv
* or a GSS_S_DEFECTIVE_TOKEN error due to garbage algorithm, filler, or
* sequence number values.
*
* 3. A pre-CFX wrap token with fewer than 16 + cksumlen bytes after the ASN.1
* header causes an integer underflow when computing the ciphertext length,
* leading to an allocation error on 32-bit platforms or a segv on 64-bit
* platforms. A pre-CFX MIC token of this size causes an input buffer
* overrun when comparing the checksum, perhaps leading to a segv.
*
* 4. A pre-CFX wrap token with fewer than conflen + padlen bytes in the
* ciphertext (where padlen is the last byte of the decrypted ciphertext)
* causes an integer underflow when computing the original message length,
* leading to an allocation error.
*
* 5. In the mechglue, truncated encapsulation in the initial context token can
* cause input buffer overruns in gss_accept_sec_context().
*
* Vulnerabilities #1 and #2 also apply to IOV unwrap, although tokens with
* fewer than 16 bytes after the ASN.1 header will be rejected.
* Vulnerabilities #2 and #5 can only be robustly detected using a
* memory-checking environment such as valgrind.
*/
#include "k5-int.h"
#include "common.h"
#include "mglueP.h"
#include "gssapiP_krb5.h"
/*
* The following samples contain context parameters and otherwise valid seal
* tokens where the plain text is padded with byte value 100 instead of the
* proper value 1.
*/
struct test {
krb5_enctype enctype;
krb5_enctype encseq_enctype;
int sealalg;
int signalg;
size_t cksum_size;
size_t keylen;
const char *keydata;
size_t toklen;
const char *token;
} tests[] = {
{
ENCTYPE_ARCFOUR_HMAC, ENCTYPE_ARCFOUR_HMAC,
SEAL_ALG_MICROSOFT_RC4, SGN_ALG_HMAC_MD5, 8,
16,
"\x66\x64\x41\x64\x55\x78\x21\xD0\xD0\xFD\x05\x6A\xFF\x6F\xE8\x09",
53,
"\x60\x33\x06\x09\x2A\x86\x48\x86\xF7\x12\x01\x02\x02\x02\x01\x11"
"\x00\x10\x00\xFF\xFF\x35\xD4\x79\xF3\x8C\x47\x8F\x6E\x23\x6F\x3E"
"\xCC\x5E\x57\x5C\x6A\x89\xF0\xA2\x03\x4F\x0B\x51\x11\xEE\x89\x7E"
"\xD6\xF6\xB5\xD6\x51"
}
};
/* Fake up enough of a CFX GSS context for gss_unwrap, using an AES key. */
static gss_ctx_id_t
make_fake_cfx_context()
{
gss_union_ctx_id_t uctx;
krb5_gss_ctx_id_t kgctx;
krb5_keyblock kb;
kgctx = calloc(1, sizeof(*kgctx));
if (kgctx == NULL)
abort();
kgctx->established = 1;
kgctx->proto = 1;
if (g_seqstate_init(&kgctx->seqstate, 0, 0, 0, 0) != 0)
abort();
kgctx->mech_used = &mech_krb5;
kgctx->sealalg = -1;
kgctx->signalg = -1;
kb.enctype = ENCTYPE_AES128_CTS_HMAC_SHA1_96;
kb.length = 16;
kb.contents = (unsigned char *)"1234567887654321";
if (krb5_k_create_key(NULL, &kb, &kgctx->subkey) != 0)
abort();
uctx = calloc(1, sizeof(*uctx));
if (uctx == NULL)
abort();
uctx->mech_type = &mech_krb5;
uctx->internal_ctx_id = (gss_ctx_id_t)kgctx;
return (gss_ctx_id_t)uctx;
}
/* Fake up enough of a GSS context for gss_unwrap, using keys from test. */
static gss_ctx_id_t
make_fake_context(const struct test *test)
{
gss_union_ctx_id_t uctx;
krb5_gss_ctx_id_t kgctx;
krb5_keyblock kb;
kgctx = calloc(1, sizeof(*kgctx));
if (kgctx == NULL)
abort();
kgctx->established = 1;
if (g_seqstate_init(&kgctx->seqstate, 0, 0, 0, 0) != 0)
abort();
kgctx->mech_used = &mech_krb5;
kgctx->sealalg = test->sealalg;
kgctx->signalg = test->signalg;
kgctx->cksum_size = test->cksum_size;
kb.enctype = test->enctype;
kb.length = test->keylen;
kb.contents = (unsigned char *)test->keydata;
if (krb5_k_create_key(NULL, &kb, &kgctx->subkey) != 0)
abort();
kb.enctype = test->encseq_enctype;
if (krb5_k_create_key(NULL, &kb, &kgctx->seq) != 0)
abort();
if (krb5_k_create_key(NULL, &kb, &kgctx->enc) != 0)
abort();
uctx = calloc(1, sizeof(*uctx));
if (uctx == NULL)
abort();
uctx->mech_type = &mech_krb5;
uctx->internal_ctx_id = (gss_ctx_id_t)kgctx;
return (gss_ctx_id_t)uctx;
}
/* Free a context created by make_fake_context. */
static void
free_fake_context(gss_ctx_id_t ctx)
{
gss_union_ctx_id_t uctx = (gss_union_ctx_id_t)ctx;
krb5_gss_ctx_id_t kgctx = (krb5_gss_ctx_id_t)uctx->internal_ctx_id;
free(kgctx->seqstate);
krb5_k_free_key(NULL, kgctx->subkey);
krb5_k_free_key(NULL, kgctx->seq);
krb5_k_free_key(NULL, kgctx->enc);
free(kgctx);
free(uctx);
}
/* Prefix a token (starting at the two-byte ID) with an ASN.1 header and return
* it in an allocated block to facilitate checking by valgrind or similar. */
static void
make_token(unsigned char *token, size_t len, gss_buffer_t out)
{
char *wrapped;
assert(mech_krb5.length == 9);
assert(len + 11 < 128);
wrapped = malloc(len + 13);
if (wrapped == NULL)
abort();
wrapped[0] = 0x60;
wrapped[1] = len + 11;
wrapped[2] = 0x06;
wrapped[3] = 9;
memcpy(wrapped + 4, mech_krb5.elements, 9);
memcpy(wrapped + 13, token, len);
out->length = len + 13;
out->value = wrapped;
}
/* Unwrap a superficially valid RFC 1964 token with a CFX-only context, with
* regular and IOV unwrap. */
static void
test_bogus_1964_token(gss_ctx_id_t ctx)
{
OM_uint32 minor, major;
unsigned char tokbuf[128];
gss_buffer_desc in, out;
gss_iov_buffer_desc iov;
store_16_be(KG_TOK_SIGN_MSG, tokbuf);
store_16_le(SGN_ALG_HMAC_MD5, tokbuf + 2);
store_16_le(SEAL_ALG_NONE, tokbuf + 4);
store_16_le(0xFFFF, tokbuf + 6);
memset(tokbuf + 8, 0, 16);
make_token(tokbuf, 24, &in);
major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
(void)gss_release_buffer(&minor, &out);
iov.type = GSS_IOV_BUFFER_TYPE_HEADER;
iov.buffer = in;
major = gss_unwrap_iov(&minor, ctx, NULL, NULL, &iov, 1);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(in.value);
}
/* Process wrap and MIC tokens with incomplete headers. */
static void
test_short_header(gss_ctx_id_t ctx)
{
OM_uint32 minor, major;
unsigned char tokbuf[128];
gss_buffer_desc in, out, empty = GSS_C_EMPTY_BUFFER;
/* Seal token, 2-24 bytes */
store_16_be(KG_TOK_SEAL_MSG, tokbuf);
make_token(tokbuf, 2, &in);
major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(in.value);
(void)gss_release_buffer(&minor, &out);
/* Sign token, 2-24 bytes */
store_16_be(KG_TOK_SIGN_MSG, tokbuf);
make_token(tokbuf, 2, &in);
major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(in.value);
(void)gss_release_buffer(&minor, &out);
/* MIC token, 2-24 bytes */
store_16_be(KG_TOK_MIC_MSG, tokbuf);
make_token(tokbuf, 2, &in);
major = gss_verify_mic(&minor, ctx, &empty, &in, NULL);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(in.value);
}
/* Process wrap and MIC tokens with incomplete headers. */
static void
test_short_header_iov(gss_ctx_id_t ctx, const struct test *test)
{
OM_uint32 minor, major;
unsigned char tokbuf[128];
gss_iov_buffer_desc iov;
/* IOV seal token, 16-23 bytes */
store_16_be(KG_TOK_SEAL_MSG, tokbuf);
store_16_le(test->signalg, tokbuf + 2);
store_16_le(test->sealalg, tokbuf + 4);
store_16_be(0xFFFF, tokbuf + 6);
memset(tokbuf + 8, 0, 8);
iov.type = GSS_IOV_BUFFER_TYPE_HEADER;
make_token(tokbuf, 16, &iov.buffer);
major = gss_unwrap_iov(&minor, ctx, NULL, NULL, &iov, 1);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(iov.buffer.value);
/* IOV sign token, 16-23 bytes */
store_16_be(KG_TOK_SIGN_MSG, tokbuf);
store_16_le(test->signalg, tokbuf + 2);
store_16_le(SEAL_ALG_NONE, tokbuf + 4);
store_16_le(0xFFFF, tokbuf + 6);
memset(tokbuf + 8, 0, 8);
iov.type = GSS_IOV_BUFFER_TYPE_HEADER;
make_token(tokbuf, 16, &iov.buffer);
major = gss_unwrap_iov(&minor, ctx, NULL, NULL, &iov, 1);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(iov.buffer.value);
/* IOV MIC token, 16-23 bytes */
store_16_be(KG_TOK_MIC_MSG, tokbuf);
store_16_be(test->signalg, tokbuf + 2);
store_16_le(SEAL_ALG_NONE, tokbuf + 4);
store_16_le(0xFFFF, tokbuf + 6);
memset(tokbuf + 8, 0, 8);
iov.type = GSS_IOV_BUFFER_TYPE_MIC_TOKEN;
make_token(tokbuf, 16, &iov.buffer);
major = gss_verify_mic_iov(&minor, ctx, NULL, &iov, 1);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(iov.buffer.value);
}
/* Process wrap and MIC tokens with incomplete checksums. */
static void
test_short_checksum(gss_ctx_id_t ctx, const struct test *test)
{
OM_uint32 minor, major;
unsigned char tokbuf[128];
gss_buffer_desc in, out, empty = GSS_C_EMPTY_BUFFER;
/* Can only do this with the DES3 checksum, as we can't easily get past
* retrieving the sequence number when the checksum is only eight bytes. */
if (test->cksum_size <= 8)
return;
/* Seal token, fewer than 16 + cksum_size bytes. Use the token from the
* test data to get a valid sequence number. */
make_token((unsigned char *)test->token + 13, 24, &in);
major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(in.value);
(void)gss_release_buffer(&minor, &out);
/* Sign token, fewer than 16 + cksum_size bytes. */
memcpy(tokbuf, test->token + 13, 24);
store_16_be(KG_TOK_SIGN_MSG, tokbuf);
store_16_le(SEAL_ALG_NONE, tokbuf + 4);
make_token(tokbuf, 24, &in);
major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(in.value);
(void)gss_release_buffer(&minor, &out);
/* MIC token, fewer than 16 + cksum_size bytes. */
memcpy(tokbuf, test->token + 13, 24);
store_16_be(KG_TOK_MIC_MSG, tokbuf);
store_16_le(SEAL_ALG_NONE, tokbuf + 4);
make_token(tokbuf, 24, &in);
major = gss_verify_mic(&minor, ctx, &empty, &in, NULL);
if (major != GSS_S_DEFECTIVE_TOKEN)
abort();
free(in.value);
}
/* Unwrap a token with a bogus padding byte in the decrypted ciphertext. */
static void
test_bad_pad(gss_ctx_id_t ctx, const struct test *test)
{
OM_uint32 minor, major;
gss_buffer_desc in, out;
in.length = test->toklen;
in.value = (char *)test->token;
major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
if (major != GSS_S_BAD_SIG)
abort();
(void)gss_release_buffer(&minor, &out);
}
static void
try_accept(void *value, size_t len)
{
OM_uint32 minor;
gss_buffer_desc in, out;
gss_ctx_id_t ctx = GSS_C_NO_CONTEXT;
/* Copy the provided value to make input overruns more obvious. */
in.value = malloc(len);
if (in.value == NULL)
abort();
memcpy(in.value, value, len);
in.length = len;
(void)gss_accept_sec_context(&minor, &ctx, GSS_C_NO_CREDENTIAL, &in,
GSS_C_NO_CHANNEL_BINDINGS, NULL, NULL,
&out, NULL, NULL, NULL);
gss_release_buffer(&minor, &out);
gss_delete_sec_context(&minor, &ctx, GSS_C_NO_BUFFER);
free(in.value);
}
/* Accept contexts using superficially valid but truncated encapsulations. */
static void
test_short_encapsulation()
{
/* Include just the initial application tag, to see if we overrun reading
* the sequence length. */
try_accept("\x60", 1);
/* Indicate four additional sequence length bytes, to see if we overrun
* reading them (or skipping them and reading the next byte). */
try_accept("\x60\x84", 2);
/* Include an object identifier tag but no length, to see if we overrun
* reading the length. */
try_accept("\x60\x40\x06", 3);
/* Include an object identifier tag with a length matching the krb5 mech,
* but no OID bytes, to see if we overrun comparing against mechs. */
try_accept("\x60\x40\x06\x09", 4);
}
int
main(int argc, char **argv)
{
gss_ctx_id_t ctx;
size_t i;
ctx = make_fake_cfx_context();
test_bogus_1964_token(ctx);
free_fake_context(ctx);
for (i = 0; i < sizeof(tests) / sizeof(*tests); i++) {
ctx = make_fake_context(&tests[i]);
test_short_header(ctx);
test_short_header_iov(ctx, &tests[i]);
test_short_checksum(ctx, &tests[i]);
test_bad_pad(ctx, &tests[i]);
free_fake_context(ctx);
}
test_short_encapsulation();
return 0;
}