t_invalid.c

/* -*- 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.)  This vulnerability also applies to IOV unwrap.
 *
 * 2. A CFX wrap token with a different value of EC between the plaintext and
 *    encrypted copies will be erroneously accepted, which allows a message
 *    truncation attack.  This vulnerability also applies to IOV unwrap.
 *
 * 3. A CFX wrap token with a plaintext length fewer than 16 bytes causes an
 *    access before the beginning of the input buffer, possibly leading to a
 *    crash.
 *
 * 4. A CFX wrap token with a plaintext EC value greater than the plaintext
 *    length - 16 causes an integer underflow when computing the result length,
 *    likely causing a crash.
 *
 * 5. An IOV unwrap operation will overrun the header buffer if an ASN.1
 *    wrapper longer than the header buffer is present.
 *
 * 6. 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.  This vulnerability also applies to IOV unwrap.
 *
 * 7. 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.
 *
 * 8. 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.
 *
 * 9. In the mechglue, truncated encapsulation in the initial context token can
 *    cause input buffer overruns in gss_accept_sec_context().
 */

#include "k5-int.h"
#include "common.h"
#include "mglueP.h"
#include "gssapiP_krb5.h"

/*
 * The following samples contain:
 * - context parameters
 * - otherwise valid seal tokens where the plain text is padded with byte value
 *   100 instead of the proper value 1.
 * - valid MIC tokens for the message "message"
 * - two valid wrap tokens for the message "message", one without
 *   confidentiality and one with
 */
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;
    size_t miclen;
    const char *mic;
    size_t wrap1len;
    const char *wrap1;
    size_t wrap2len;
    const char *wrap2;
} tests[] = {
    {
        ENCTYPE_DES3_CBC_SHA1, ENCTYPE_DES3_CBC_RAW,
        SEAL_ALG_DES3KD, SGN_ALG_HMAC_SHA1_DES3_KD, 20,
        24,
        "\x4F\xEA\x19\x19\x5E\x0E\x10\xDF\x3D\x29\xB5\x13\x8F\x01\xC7\xA7"
        "\x92\x3D\x38\xF7\x26\x73\x0D\x6D",
        65,
        "\x60\x3F\x06\x09\x2A\x86\x48\x86\xF7\x12\x01\x02\x02\x02\x01\x04"
        "\x00\x02\x00\xFF\xFF\xEB\xF3\x9A\x89\x24\x57\xB8\x63\x95\x25\xE8"
        "\x6E\x8E\x79\xE6\x2E\xCA\xD3\xFF\x57\x9F\x8C\xAB\xEF\xDD\x28\x10"
        "\x2F\x93\x21\x2E\xF2\x52\xB6\x6F\xA8\xBB\x8A\x6D\xAA\x6F\xB7\xF4\xD4",
        49,
        "\x60\x2F\x06\x09\x2A\x86\x48\x86\xF7\x12\x01\x02\x02\x01\x01\x04"
        "\x00\xFF\xFF\xFF\xFF\x57\xF5\x77\xC6\xC0\x72\x26\x97\x00\x89\xB2"
        "\xEE\xD9\xD1\x90\xE7\x11\x50\x4F\xE9\x59\x18\xB1\x8F\x82\x8E\x8F\x5E",
        65,
        "\x60\x3F\x06\x09\x2A\x86\x48\x86\xF7\x12\x01\x02\x02\x02\x01\x04"
        "\x00\xFF\xFF\xFF\xFF\x0B\x81\x56\x4A\x02\x1B\xBE\x83\x2B\x35\x08"
        "\x7B\x49\x15\x07\x97\x6A\x64\xEF\xDD\x32\x52\xF0\xA2\xE2\x62\x9B"
        "\xA7\x72\xF7\x3D\x6B\x2D\xAC\x21\xE9\x6D\x65\x73\x73\x61\x67\x65\x01",
        65,
        "\x60\x3F\x06\x09\x2A\x86\x48\x86\xF7\x12\x01\x02\x02\x02\x01\x04"
        "\x00\x02\x00\xFF\xFF\x66\x5A\xE1\xC8\x4F\x69\x33\x97\x5D\x05\xE2"
        "\x86\x40\x14\x15\x14\x27\x01\x9F\x32\x9D\x82\xF4\xE1\xC5\x3E\xFA"
        "\x6D\x7D\x05\x39\xAE\x21\x44\xA0\x87\xA6\x24\xED\xFC\xA3\x53\xF1\x30"
    },
    {
        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",
        37,
        "\x60\x23\x06\x09\x2A\x86\x48\x86\xF7\x12\x01\x02\x02\x01\x01\x11"
        "\x00\xFF\xFF\xFF\xFF\x5D\xE7\x51\xF6\xFB\x6C\x25\x5B\x23\x93\x5A"
        "\x30\x20\x57\xDC\xB5",
        53,
        "\x60\x33\x06\x09\x2A\x86\x48\x86\xF7\x12\x01\x02\x02\x02\x01\x11"
        "\x00\xFF\xFF\xFF\xFF\xAD\xB5\x1D\x01\x39\x7B\xA2\x16\x4C\x1B\x68"
        "\x18\xEC\xAC\xD9\xE5\x9E\xD1\x41\x7A\x89\xE8\xCB\x24\x6D\x65\x73"
        "\x73\x61\x67\x65\x01",
        53,
        "\x60\x33\x06\x09\x2A\x86\x48\x86\xF7\x12\x01\x02\x02\x02\x01\x11"
        "\x00\x10\x00\xFF\xFF\xDD\x6D\x04\xEA\x64\x5C\xE7\x31\x50\xD0\x09"
        "\x44\x9E\x67\xA4\x30\xEC\xFB\xFF\xC0\xF7\x16\x1E\x14\x1A\x82\x42"
        "\xDD\x26\x23\x2B\x02"
    }
};

static void *
ealloc(size_t len)
{
    void *ptr = calloc(len, 1);

    if (ptr == NULL)
        abort();
    return ptr;
}

/* Fake up enough of a CFX GSS context for gss_unwrap, using an AES key.
 * The context takes ownership of subkey. */
static gss_ctx_id_t
make_fake_cfx_context(krb5_key subkey)
{
    gss_union_ctx_id_t uctx;
    krb5_gss_ctx_id_t kgctx;

    kgctx = ealloc(sizeof(*kgctx));
    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;

    kgctx->subkey = subkey;
    kgctx->cksumtype = CKSUMTYPE_HMAC_SHA1_96_AES128;

    uctx = ealloc(sizeof(*uctx));
    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 = ealloc(sizeof(*kgctx));
    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 = ealloc(sizeof(*uctx));
    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 = ealloc(len + 13);
    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;
}

/* Create a 16-byte header for a CFX confidential wrap token to be processed by
 * the fake CFX context. */
static void
write_cfx_header(uint16_t ec, uint8_t *out)
{
    memset(out, 0, 16);
    store_16_be(KG2_TOK_WRAP_MSG, out);
    out[2] = FLAG_WRAP_CONFIDENTIAL;
    out[3] = 0xFF;
    store_16_be(ec, out + 4);
}

/* 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);
}

static void
test_cfx_altered_ec(gss_ctx_id_t ctx, krb5_key subkey)
{
    OM_uint32 major, minor;
    uint8_t tokbuf[128], plainbuf[24];
    krb5_data plain;
    krb5_enc_data cipher;
    gss_buffer_desc in, out;
    gss_iov_buffer_desc iov[2];

    /* Construct a header with a plaintext EC value of 3. */
    write_cfx_header(3, tokbuf);

    /* Encrypt a plaintext and a copy of the header with the EC value 0. */
    memcpy(plainbuf, "truncate", 8);
    memcpy(plainbuf + 8, tokbuf, 16);
    store_16_be(0, plainbuf + 12);
    plain = make_data(plainbuf, 24);
    cipher.ciphertext.data = (char *)tokbuf + 16;
    cipher.ciphertext.length = sizeof(tokbuf) - 16;
    cipher.enctype = subkey->keyblock.enctype;
    if (krb5_k_encrypt(NULL, subkey, KG_USAGE_INITIATOR_SEAL, NULL,
                       &plain, &cipher) != 0)
        abort();

    /* Verify that the token is rejected by gss_unwrap(). */
    in.value = tokbuf;
    in.length = 16 + cipher.ciphertext.length;
    major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
    if (major != GSS_S_DEFECTIVE_TOKEN)
        abort();
    (void)gss_release_buffer(&minor, &out);

    /* Verify that the token is rejected by gss_unwrap_iov(). */
    iov[0].type = GSS_IOV_BUFFER_TYPE_STREAM;
    iov[0].buffer = in;
    iov[1].type = GSS_IOV_BUFFER_TYPE_DATA;
    major = gss_unwrap_iov(&minor, ctx, NULL, NULL, iov, 2);
    if (major != GSS_S_DEFECTIVE_TOKEN)
        abort();
}

static void
test_cfx_short_plaintext(gss_ctx_id_t ctx, krb5_key subkey)
{
    OM_uint32 major, minor;
    uint8_t tokbuf[128], zerobyte = 0;
    krb5_data plain;
    krb5_enc_data cipher;
    gss_buffer_desc in, out;

    write_cfx_header(0, tokbuf);

    /* Encrypt a single byte, with no copy of the header. */
    plain = make_data(&zerobyte, 1);
    cipher.ciphertext.data = (char *)tokbuf + 16;
    cipher.ciphertext.length = sizeof(tokbuf) - 16;
    cipher.enctype = subkey->keyblock.enctype;
    if (krb5_k_encrypt(NULL, subkey, KG_USAGE_INITIATOR_SEAL, NULL,
                       &plain, &cipher) != 0)
        abort();

    /* Verify that the token is rejected by gss_unwrap(). */
    in.value = tokbuf;
    in.length = 16 + cipher.ciphertext.length;
    major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
    if (major != GSS_S_DEFECTIVE_TOKEN)
        abort();
    (void)gss_release_buffer(&minor, &out);
}

static void
test_cfx_large_ec(gss_ctx_id_t ctx, krb5_key subkey)
{
    OM_uint32 major, minor;
    uint8_t tokbuf[128] = { 0 }, plainbuf[20];
    krb5_data plain;
    krb5_enc_data cipher;
    gss_buffer_desc in, out;

    /* Construct a header with an EC value of 5. */
    write_cfx_header(5, tokbuf);

    /* Encrypt a 4-byte plaintext plus the header. */
    memcpy(plainbuf, "abcd", 4);
    memcpy(plainbuf + 4, tokbuf, 16);
    plain = make_data(plainbuf, 20);
    cipher.ciphertext.data = (char *)tokbuf + 16;
    cipher.ciphertext.length = sizeof(tokbuf) - 16;
    cipher.enctype = subkey->keyblock.enctype;
    if (krb5_k_encrypt(NULL, subkey, KG_USAGE_INITIATOR_SEAL, NULL,
                       &plain, &cipher) != 0)
        abort();

    /* Verify that the token is rejected by gss_unwrap(). */
    in.value = tokbuf;
    in.length = 16 + cipher.ciphertext.length;
    major = gss_unwrap(&minor, ctx, &in, &out, NULL, NULL);
    if (major != GSS_S_DEFECTIVE_TOKEN)
        abort();
    (void)gss_release_buffer(&minor, &out);
}

static void
test_iov_large_asn1_wrapper(gss_ctx_id_t ctx)
{
    OM_uint32 minor, major;
    uint8_t databuf[10] = { 0 };
    gss_iov_buffer_desc iov[2];

    /*
     * In this IOV array, the header contains a DER tag with a dangling eight
     * bytes of length field.  The data IOV indicates a total token length
     * sufficient to contain the length bytes.
     */
    iov[0].type = GSS_IOV_BUFFER_TYPE_HEADER;
    iov[0].buffer.value = ealloc(2);
    iov[0].buffer.length = 2;
    memcpy(iov[0].buffer.value, "\x60\x88", 2);
    iov[1].type = GSS_IOV_BUFFER_TYPE_DATA;
    iov[1].buffer.value = databuf;
    iov[1].buffer.length = 10;
    major = gss_unwrap_iov(&minor, ctx, NULL, NULL, iov, 2);
    if (major != GSS_S_DEFECTIVE_TOKEN)
        abort();
    free(iov[0].buffer.value);
}

/* Verify that token is a valid MIC token for ctx and message, and that
 * changing any of the input bytes yields one of the expected errors. */
static void
mictest(gss_ctx_id_t ctx, gss_buffer_t message, gss_buffer_t token)
{
    OM_uint32 major, minor;
    size_t i;
    uint8_t *p;

    major = gss_verify_mic(&minor, ctx, message, token, NULL);
    check_gsserr("gss_verify_mic", major, minor);

    p = token->value;
    for (i = 0; i < token->length; i++) {
        /* Skip sequence number bytes for RC4. */
        if (load_16_le(p + 15) == SGN_ALG_HMAC_MD5 && i >= 21 && i <= 24)
            continue;
        p[i]++;
        major = gss_verify_mic(&minor, ctx, message, token, NULL);
        if (major != GSS_S_DEFECTIVE_TOKEN && major != GSS_S_BAD_SIG)
            abort();
        p[i]--;
    }
    p = message->value;
    for (i = 0; i < message->length; i++) {
        p[i]++;
        major = gss_verify_mic(&minor, ctx, message, token, NULL);
        if (major != GSS_S_DEFECTIVE_TOKEN && major != GSS_S_BAD_SIG)
            abort();
        p[i]--;
    }
}

static void
test_cfx_verify_mic(gss_ctx_id_t ctx)
{
    gss_buffer_desc message, token;
    uint8_t msg[] = "message";
    uint8_t mic[] = "\x04\x04\x00\xFF\xFF\xFF\xFF\xFF"
        "\x00\x00\x00\x00\x00\x00\x00\x00\x97\xE9\x63\x3F\x9D\x82\x2B\x74"
        "\x67\x94\x8A\xD0";

    message.value = msg;
    message.length = sizeof(msg) - 1;
    token.value = mic;
    token.length = sizeof(mic) - 1;
    mictest(ctx, &message, &token);
}

static void
test_verify_mic(gss_ctx_id_t ctx, const struct test *test)
{
    gss_buffer_desc message, token;
    uint8_t msg[] = "message", buf[128];

    assert(test->miclen <= sizeof(buf));
    memcpy(buf, test->mic, test->miclen);

    message.value = msg;
    message.length = sizeof(msg) - 1;
    token.value = buf;
    token.length = test->miclen;
    mictest(ctx, &message, &token);
}

/* Verify that token is a valid wrap token for ctx unwrapping to message, and
 * that changing any of the token bytes yields one of the expected errors. */
static void
unwraptest(gss_ctx_id_t ctx, gss_buffer_t message, gss_buffer_t token)
{
    OM_uint32 major, minor;
    gss_buffer_desc unwrapped;
    size_t i;
    uint8_t *p;

    major = gss_unwrap(&minor, ctx, token, &unwrapped, NULL, NULL);
    check_gsserr("gss_unwrap", major, minor);
    if (unwrapped.length != message->length ||
        memcmp(unwrapped.value, message->value, unwrapped.length) != 0)
        abort();
    gss_release_buffer(&minor, &unwrapped);

    p = token->value;
    for (i = 0; i < token->length; i++) {
        /* Skip sequence number bytes for RC4. */
        if (load_16_le(p + 15) == SGN_ALG_HMAC_MD5 && i >= 21 && i <= 24)
            continue;
        p[i]++;
        major = gss_unwrap(&minor, ctx, token, &unwrapped, NULL, NULL);
        if (major != GSS_S_DEFECTIVE_TOKEN && major != GSS_S_BAD_SIG)
            abort();
        p[i]--;
    }
}

static void
test_cfx_unwrap(gss_ctx_id_t ctx)
{
    gss_buffer_desc message, token;
    uint8_t msg[] = "message";
    uint8_t token1[] = "\x05\x04\x00\xFF\x00\x0C\x00\x00"
        "\x00\x00\x00\x00\x00\x00\x00\x00\x6D\x65\x73\x73\x61\x67\x65\xDF"
        "\x57\xB9\x5E\xA2\xB1\x73\x31\xDB\xCE\x61\x62";
    uint8_t token2[] = "\x05\x04\x02\xFF\x00\x00\x00\x00"
        "\x00\x00\x00\x00\x00\x00\x00\x00\x72\xBB\xD7\xCF\xDE\xB0\xF9\x20"
        "\xE2\x9A\x98\xA7\xA4\xE7\xC9\x9B\x30\xD3\xFE\x61\x51\x2E\x1B\x56"
        "\x88\xB7\x8A\xF5\xA9\xBF\x8F\x82\xB1\xEB\xCC\x88\xE6\x33\x13\xBF"
        "\x52\x4B\xC0\x3B\x24\x3F\x3E\xF5\xF1\xE0\x64";

    message.value = msg;
    message.length = sizeof(msg) - 1;
    token.value = token1;
    token.length = sizeof(token1) - 1;
    unwraptest(ctx, &message, &token);
    token.value = token2;
    token.length = sizeof(token2) - 1;
    unwraptest(ctx, &message, &token);
}

static void
test_unwrap(gss_ctx_id_t ctx, const struct test *test)
{
    gss_buffer_desc message, token;
    uint8_t msg[] = "message", buf[128];

    assert(test->wrap1len <= sizeof(buf) && test->wrap2len <= sizeof(buf));
    token.value = buf;

    message.value = msg;
    message.length = sizeof(msg) - 1;
    memcpy(buf, test->wrap1, test->wrap1len);
    token.length = test->wrap1len;
    unwraptest(ctx, &message, &token);
    memcpy(buf, test->wrap2, test->wrap2len);
    token.length = test->wrap2len;
    unwraptest(ctx, &message, &token);
}

/* 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 = ealloc(len);
    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(void)
{
    /* 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)
{
    krb5_keyblock kb;
    krb5_key cfx_subkey;
    gss_ctx_id_t ctx;
    size_t i;

    kb.enctype = ENCTYPE_AES128_CTS_HMAC_SHA1_96;
    kb.length = 16;
    kb.contents = (unsigned char *)"1234567887654321";
    if (krb5_k_create_key(NULL, &kb, &cfx_subkey) != 0)
        abort();

    ctx = make_fake_cfx_context(cfx_subkey);
    test_bogus_1964_token(ctx);
    test_cfx_altered_ec(ctx, cfx_subkey);
    test_cfx_short_plaintext(ctx, cfx_subkey);
    test_cfx_large_ec(ctx, cfx_subkey);
    test_iov_large_asn1_wrapper(ctx);
    test_cfx_verify_mic(ctx);
    test_cfx_unwrap(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]);
        test_verify_mic(ctx, &tests[i]);
        test_unwrap(ctx, &tests[i]);
        free_fake_context(ctx);
    }

    test_short_encapsulation();

    return 0;
}