void
DecryptionManager::PacketHandler::decryptApplicationMessage(bool fromClient) {
// Split and coalesce the cipher data into a continuous buffer
unique_ptr<IOBuf> msg = cipher_->split(cipher_->chainLength());
msg->coalesce();
// Start decryption. This is mostly copied from k5sealv3.c.
krb5_error_code code;
unsigned char *ptr;
unsigned int bodysize;
ptr = (unsigned char *)msg->data() + 4;
code = gssint_g_verify_token_header(gss_mech_krb5, // always use krb5
&bodysize,
&ptr,
-1,
msg->length() - 4,
0);
if (code) {
onError("Failed to verify application message header");
return;
}
size_t ec = load_16_be(ptr+4);
size_t rrc = load_16_be(ptr+6);
if (!gss_krb5int_rotate_left(ptr+16, bodysize-16, rrc)) {
throw std::runtime_error("Cannot allocate memory");
}
krb5_enc_data cipher;
krb5_data plain;
int keyUsage;
cipher.enctype = subkey_->enctype;
cipher.ciphertext.length = bodysize - 16;
cipher.ciphertext.data = (char*)ptr + 16;
plain.length = bodysize - 16;
plain.data = (char*)malloc(plain.length);
if (!plain.data) {
throw std::runtime_error("Cannot allocate memory");
}
SCOPE_EXIT {
free(plain.data);
};
keyUsage = (fromClient ? KG_USAGE_INITIATOR_SEAL : KG_USAGE_ACCEPTOR_SEAL);
code = krb5_c_decrypt(ctx_->get(), subkey_, keyUsage, 0, &cipher, &plain);
if (code) {
onError("Cannot decrypt application message");
return;
}
decryptedMessages_.push_back(IOBuf::copyBuffer(plain.data,
plain.length - ec - 16));
}
krb5_error_code
gss_krb5int_make_seal_token_v3 (krb5_context context,
krb5_gss_ctx_id_rec *ctx,
const gss_buffer_desc * message,
gss_buffer_t token,
int conf_req_flag, int toktype)
{
size_t bufsize = 16;
unsigned char *outbuf = 0;
krb5_error_code err;
int key_usage;
unsigned char acceptor_flag;
const gss_buffer_desc *message2 = message;
#ifdef CFX_EXERCISE
size_t rrc;
#endif
size_t ec;
unsigned short tok_id;
krb5_checksum sum;
krb5_key key;
krb5_cksumtype cksumtype;
acceptor_flag = ctx->initiate ? 0 : FLAG_SENDER_IS_ACCEPTOR;
key_usage = (toktype == KG_TOK_WRAP_MSG
? (ctx->initiate
? KG_USAGE_INITIATOR_SEAL
: KG_USAGE_ACCEPTOR_SEAL)
: (ctx->initiate
? KG_USAGE_INITIATOR_SIGN
: KG_USAGE_ACCEPTOR_SIGN));
if (ctx->have_acceptor_subkey) {
key = ctx->acceptor_subkey;
cksumtype = ctx->acceptor_subkey_cksumtype;
} else {
key = ctx->subkey;
cksumtype = ctx->cksumtype;
}
assert(key != NULL);
#ifdef CFX_EXERCISE
{
static int initialized = 0;
if (!initialized) {
srand(time(0));
initialized = 1;
}
}
#endif
if (toktype == KG_TOK_WRAP_MSG && conf_req_flag) {
krb5_data plain;
krb5_enc_data cipher;
size_t ec_max;
/* 300: Adds some slop. */
if (SIZE_MAX - 300 < message->length)
return ENOMEM;
ec_max = SIZE_MAX - message->length - 300;
if (ec_max > 0xffff)
ec_max = 0xffff;
#ifdef CFX_EXERCISE
/* For testing only. For performance, always set ec = 0. */
ec = ec_max & rand();
#else
ec = 0;
#endif
plain.length = message->length + 16 + ec;
plain.data = malloc(message->length + 16 + ec);
if (plain.data == NULL)
return ENOMEM;
/* Get size of ciphertext. */
bufsize = 16 + krb5_encrypt_size (plain.length, key->keyblock.enctype);
/* Allocate space for header plus encrypted data. */
outbuf = gssalloc_malloc(bufsize);
if (outbuf == NULL) {
free(plain.data);
return ENOMEM;
}
/* TOK_ID */
store_16_be(KG2_TOK_WRAP_MSG, outbuf);
/* flags */
outbuf[2] = (acceptor_flag
| (conf_req_flag ? FLAG_WRAP_CONFIDENTIAL : 0)
| (ctx->have_acceptor_subkey ? FLAG_ACCEPTOR_SUBKEY : 0));
/* filler */
outbuf[3] = 0xff;
/* EC */
store_16_be(ec, outbuf+4);
/* RRC */
store_16_be(0, outbuf+6);
store_64_be(ctx->seq_send, outbuf+8);
memcpy(plain.data, message->value, message->length);
if (ec != 0)
memset(plain.data + message->length, 'x', ec);
memcpy(plain.data + message->length + ec, outbuf, 16);
cipher.ciphertext.data = (char *)outbuf + 16;
cipher.ciphertext.length = bufsize - 16;
cipher.enctype = key->keyblock.enctype;
err = krb5_k_encrypt(context, key, key_usage, 0, &plain, &cipher);
zap(plain.data, plain.length);
free(plain.data);
plain.data = 0;
if (err)
goto error;
/* Now that we know we're returning a valid token.... */
ctx->seq_send++;
#ifdef CFX_EXERCISE
rrc = rand() & 0xffff;
if (gss_krb5int_rotate_left(outbuf+16, bufsize-16,
(bufsize-16) - (rrc % (bufsize - 16))))
store_16_be(rrc, outbuf+6);
/* If the rotate fails, don't worry about it. */
#endif
} else if (toktype == KG_TOK_WRAP_MSG && !conf_req_flag) {
krb5_data plain;
size_t cksumsize;
/* Here, message is the application-supplied data; message2 is
what goes into the output token. They may be the same, or
message2 may be empty (for MIC). */
tok_id = KG2_TOK_WRAP_MSG;
wrap_with_checksum:
plain.length = message->length + 16;
plain.data = malloc(message->length + 16);
if (plain.data == NULL)
return ENOMEM;
err = krb5_c_checksum_length(context, cksumtype, &cksumsize);
if (err)
goto error;
assert(cksumsize <= 0xffff);
bufsize = 16 + message2->length + cksumsize;
outbuf = gssalloc_malloc(bufsize);
if (outbuf == NULL) {
free(plain.data);
plain.data = 0;
err = ENOMEM;
goto error;
}
/* TOK_ID */
store_16_be(tok_id, outbuf);
/* flags */
outbuf[2] = (acceptor_flag
| (ctx->have_acceptor_subkey ? FLAG_ACCEPTOR_SUBKEY : 0));
/* filler */
outbuf[3] = 0xff;
if (toktype == KG_TOK_WRAP_MSG) {
/* Use 0 for checksum calculation, substitute
checksum length later. */
/* EC */
store_16_be(0, outbuf+4);
/* RRC */
store_16_be(0, outbuf+6);
} else {
/* MIC and DEL store 0xFF in EC and RRC. */
store_16_be(0xffff, outbuf+4);
store_16_be(0xffff, outbuf+6);
}
store_64_be(ctx->seq_send, outbuf+8);
memcpy(plain.data, message->value, message->length);
memcpy(plain.data + message->length, outbuf, 16);
/* Fill in the output token -- data contents, if any, and
space for the checksum. */
if (message2->length)
memcpy(outbuf + 16, message2->value, message2->length);
sum.contents = outbuf + 16 + message2->length;
sum.length = cksumsize;
err = krb5_k_make_checksum(context, cksumtype, key,
key_usage, &plain, &sum);
zap(plain.data, plain.length);
free(plain.data);
plain.data = 0;
if (err) {
zap(outbuf,bufsize);
goto error;
}
if (sum.length != cksumsize)
abort();
memcpy(outbuf + 16 + message2->length, sum.contents, cksumsize);
krb5_free_checksum_contents(context, &sum);
sum.contents = 0;
/* Now that we know we're actually generating the token... */
ctx->seq_send++;
if (toktype == KG_TOK_WRAP_MSG) {
#ifdef CFX_EXERCISE
rrc = rand() & 0xffff;
/* If the rotate fails, don't worry about it. */
if (gss_krb5int_rotate_left(outbuf+16, bufsize-16,
(bufsize-16) - (rrc % (bufsize - 16))))
store_16_be(rrc, outbuf+6);
#endif
/* Fix up EC field. */
store_16_be(cksumsize, outbuf+4);
} else {
store_16_be(0xffff, outbuf+6);
}
} else if (toktype == KG_TOK_MIC_MSG) {
tok_id = KG2_TOK_MIC_MSG;
message2 = &empty_message;
goto wrap_with_checksum;
} else if (toktype == KG_TOK_DEL_CTX) {
tok_id = KG2_TOK_DEL_CTX;
message = message2 = &empty_message;
goto wrap_with_checksum;
} else
abort();
token->value = outbuf;
token->length = bufsize;
return 0;
error:
gssalloc_free(outbuf);
token->value = NULL;
token->length = 0;
return err;
}
OM_uint32
gss_krb5int_unseal_token_v3(krb5_context *contextptr,
OM_uint32 *minor_status,
krb5_gss_ctx_id_rec *ctx,
unsigned char *ptr, unsigned int bodysize,
gss_buffer_t message_buffer,
int *conf_state, gss_qop_t *qop_state, int toktype)
{
krb5_context context = *contextptr;
krb5_data plain;
gssint_uint64 seqnum;
size_t ec, rrc;
int key_usage;
unsigned char acceptor_flag;
krb5_checksum sum;
krb5_error_code err;
krb5_boolean valid;
krb5_key key;
krb5_cksumtype cksumtype;
if (qop_state)
*qop_state = GSS_C_QOP_DEFAULT;
acceptor_flag = ctx->initiate ? FLAG_SENDER_IS_ACCEPTOR : 0;
key_usage = (toktype == KG_TOK_WRAP_MSG
? (!ctx->initiate
? KG_USAGE_INITIATOR_SEAL
: KG_USAGE_ACCEPTOR_SEAL)
: (!ctx->initiate
? KG_USAGE_INITIATOR_SIGN
: KG_USAGE_ACCEPTOR_SIGN));
/* Oops. I wrote this code assuming ptr would be at the start of
the token header. */
ptr -= 2;
bodysize += 2;
if (bodysize < 16) {
defective:
*minor_status = 0;
return GSS_S_DEFECTIVE_TOKEN;
}
if ((ptr[2] & FLAG_SENDER_IS_ACCEPTOR) != acceptor_flag) {
*minor_status = (OM_uint32)G_BAD_DIRECTION;
return GSS_S_BAD_SIG;
}
/* Two things to note here.
First, we can't really enforce the use of the acceptor's subkey,
if we're the acceptor; the initiator may have sent messages
before getting the subkey. We could probably enforce it if
we're the initiator.
Second, if someone tweaks the code to not set the flag telling
the krb5 library to generate a new subkey in the AP-REP
message, the MIT library may include a subkey anyways --
namely, a copy of the AP-REQ subkey, if it was provided. So
the initiator may think we wanted a subkey, and set the flag,
even though we weren't trying to set the subkey. The "other"
key, the one not asserted by the acceptor, will have the same
value in that case, though, so we can just ignore the flag. */
if (ctx->have_acceptor_subkey && (ptr[2] & FLAG_ACCEPTOR_SUBKEY)) {
key = ctx->acceptor_subkey;
cksumtype = ctx->acceptor_subkey_cksumtype;
} else {
key = ctx->subkey;
cksumtype = ctx->cksumtype;
}
assert(key != NULL);
if (toktype == KG_TOK_WRAP_MSG) {
if (load_16_be(ptr) != KG2_TOK_WRAP_MSG)
goto defective;
if (ptr[3] != 0xff)
goto defective;
ec = load_16_be(ptr+4);
rrc = load_16_be(ptr+6);
seqnum = load_64_be(ptr+8);
if (!gss_krb5int_rotate_left(ptr+16, bodysize-16, rrc)) {
no_mem:
*minor_status = ENOMEM;
return GSS_S_FAILURE;
}
if (ptr[2] & FLAG_WRAP_CONFIDENTIAL) {
/* confidentiality */
krb5_enc_data cipher;
unsigned char *althdr;
if (conf_state)
*conf_state = 1;
/* Do we have no decrypt_size function?
For all current cryptosystems, the ciphertext size will
be larger than the plaintext size. */
cipher.enctype = key->keyblock.enctype;
cipher.ciphertext.length = bodysize - 16;
cipher.ciphertext.data = (char *)ptr + 16;
plain.length = bodysize - 16;
plain.data = gssalloc_malloc(plain.length);
if (plain.data == NULL)
goto no_mem;
err = krb5_k_decrypt(context, key, key_usage, 0,
&cipher, &plain);
if (err) {
gssalloc_free(plain.data);
goto error;
}
/* Don't use bodysize here! Use the fact that
cipher.ciphertext.length has been adjusted to the
correct length. */
althdr = (unsigned char *)plain.data + plain.length - 16;
if (load_16_be(althdr) != KG2_TOK_WRAP_MSG
|| althdr[2] != ptr[2]
|| althdr[3] != ptr[3]
|| memcmp(althdr+8, ptr+8, 8)) {
free(plain.data);
goto defective;
}
message_buffer->value = plain.data;
message_buffer->length = plain.length - ec - 16;
if(message_buffer->length == 0) {
gssalloc_free(message_buffer->value);
message_buffer->value = NULL;
}
} else {
size_t cksumsize;
err = krb5_c_checksum_length(context, cksumtype, &cksumsize);
if (err)
goto error;
/* no confidentiality */
if (conf_state)
*conf_state = 0;
if (ec + 16 < ec)
/* overflow check */
goto defective;
if (ec + 16 > bodysize)
goto defective;
/* We have: header | msg | cksum.
We need cksum(msg | header).
Rotate the first two. */
store_16_be(0, ptr+4);
store_16_be(0, ptr+6);
plain.length = bodysize-ec;
plain.data = (char *)ptr;
if (!gss_krb5int_rotate_left(ptr, bodysize-ec, 16))
goto no_mem;
sum.length = ec;
if (sum.length != cksumsize) {
*minor_status = 0;
return GSS_S_BAD_SIG;
}
sum.contents = ptr+bodysize-ec;
sum.checksum_type = cksumtype;
err = krb5_k_verify_checksum(context, key, key_usage,
&plain, &sum, &valid);
if (err)
goto error;
if (!valid) {
*minor_status = 0;
return GSS_S_BAD_SIG;
}
message_buffer->length = plain.length - 16;
message_buffer->value = gssalloc_malloc(message_buffer->length);
if (message_buffer->value == NULL)
goto no_mem;
memcpy(message_buffer->value, plain.data, message_buffer->length);
}
err = g_order_check(&ctx->seqstate, seqnum);
*minor_status = 0;
return err;
} else if (toktype == KG_TOK_MIC_MSG) {
/* wrap token, no confidentiality */
if (load_16_be(ptr) != KG2_TOK_MIC_MSG)
goto defective;
verify_mic_1:
if (ptr[3] != 0xff)
goto defective;
if (load_32_be(ptr+4) != 0xffffffffL)
goto defective;
seqnum = load_64_be(ptr+8);
plain.length = message_buffer->length + 16;
plain.data = malloc(plain.length);
if (plain.data == NULL)
goto no_mem;
if (message_buffer->length)
memcpy(plain.data, message_buffer->value, message_buffer->length);
memcpy(plain.data + message_buffer->length, ptr, 16);
sum.length = bodysize - 16;
sum.contents = ptr + 16;
sum.checksum_type = cksumtype;
err = krb5_k_verify_checksum(context, key, key_usage,
&plain, &sum, &valid);
free(plain.data);
plain.data = NULL;
if (err) {
error:
*minor_status = err;
save_error_info(*minor_status, context);
return GSS_S_BAD_SIG; /* XXX */
}
if (!valid) {
*minor_status = 0;
return GSS_S_BAD_SIG;
}
err = g_order_check(&ctx->seqstate, seqnum);
*minor_status = 0;
return err;
} else if (toktype == KG_TOK_DEL_CTX) {
if (load_16_be(ptr) != KG2_TOK_DEL_CTX)
goto defective;
message_buffer = (gss_buffer_t)&empty_message;
goto verify_mic_1;
} else {
goto defective;
}
}
/*
* Split a STREAM | SIGN_DATA | DATA into
* HEADER | SIGN_DATA | DATA | PADDING | TRAILER
*/
static OM_uint32
kg_unseal_stream_iov(OM_uint32 *minor_status,
krb5_gss_ctx_id_rec *ctx,
int *conf_state,
gss_qop_t *qop_state,
gss_iov_buffer_desc *iov,
int iov_count,
int toktype)
{
unsigned char *ptr;
unsigned int bodysize;
OM_uint32 code = 0, major_status = GSS_S_FAILURE;
krb5_context context = ctx->k5_context;
int conf_req_flag, toktype2;
int i = 0, j;
gss_iov_buffer_desc *tiov = NULL;
gss_iov_buffer_t stream, data = NULL;
gss_iov_buffer_t theader, tdata = NULL, tpadding, ttrailer;
assert(toktype == KG_TOK_WRAP_MSG);
if (toktype != KG_TOK_WRAP_MSG || (ctx->gss_flags & GSS_C_DCE_STYLE)) {
code = EINVAL;
goto cleanup;
}
stream = kg_locate_iov(iov, iov_count, GSS_IOV_BUFFER_TYPE_STREAM);
assert(stream != NULL);
ptr = (unsigned char *)stream->buffer.value;
code = g_verify_token_header(ctx->mech_used,
&bodysize, &ptr, -1,
stream->buffer.length, 0);
if (code != 0) {
major_status = GSS_S_DEFECTIVE_TOKEN;
goto cleanup;
}
if (bodysize < 2) {
*minor_status = (OM_uint32)G_BAD_TOK_HEADER;
return GSS_S_DEFECTIVE_TOKEN;
}
toktype2 = load_16_be(ptr);
ptr += 2;
bodysize -= 2;
tiov = (gss_iov_buffer_desc *)calloc((size_t)iov_count + 2, sizeof(gss_iov_buffer_desc));
if (tiov == NULL) {
code = ENOMEM;
goto cleanup;
}
/* HEADER */
theader = &tiov[i++];
theader->type = GSS_IOV_BUFFER_TYPE_HEADER;
theader->buffer.value = stream->buffer.value;
theader->buffer.length = ptr - (unsigned char *)stream->buffer.value;
if (bodysize < 14 ||
stream->buffer.length != theader->buffer.length + bodysize) {
major_status = GSS_S_DEFECTIVE_TOKEN;
goto cleanup;
}
theader->buffer.length += 14;
/* n[SIGN_DATA] | DATA | m[SIGN_DATA] */
for (j = 0; j < iov_count; j++) {
OM_uint32 type = GSS_IOV_BUFFER_TYPE(iov[j].type);
if (type == GSS_IOV_BUFFER_TYPE_DATA) {
if (data != NULL) {
/* only a single DATA buffer can appear */
code = EINVAL;
goto cleanup;
}
data = &iov[j];
tdata = &tiov[i];
}
if (type == GSS_IOV_BUFFER_TYPE_DATA ||
type == GSS_IOV_BUFFER_TYPE_SIGN_ONLY)
tiov[i++] = iov[j];
}
if (data == NULL) {
/* a single DATA buffer must be present */
code = EINVAL;
goto cleanup;
}
/* PADDING | TRAILER */
tpadding = &tiov[i++];
tpadding->type = GSS_IOV_BUFFER_TYPE_PADDING;
tpadding->buffer.length = 0;
tpadding->buffer.value = NULL;
ttrailer = &tiov[i++];
ttrailer->type = GSS_IOV_BUFFER_TYPE_TRAILER;
switch (toktype2) {
case KG2_TOK_MIC_MSG:
case KG2_TOK_WRAP_MSG:
case KG2_TOK_DEL_CTX: {
size_t ec, rrc;
krb5_enctype enctype;
unsigned int k5_headerlen = 0;
unsigned int k5_trailerlen = 0;
if (ctx->have_acceptor_subkey)
enctype = ctx->acceptor_subkey->keyblock.enctype;
else
enctype = ctx->subkey->keyblock.enctype;
conf_req_flag = ((ptr[0] & FLAG_WRAP_CONFIDENTIAL) != 0);
ec = conf_req_flag ? load_16_be(ptr + 2) : 0;
rrc = load_16_be(ptr + 4);
if (rrc != 0) {
if (!gss_krb5int_rotate_left((unsigned char *)stream->buffer.value + 16,
stream->buffer.length - 16, rrc)) {
code = ENOMEM;
goto cleanup;
}
store_16_be(0, ptr + 4); /* set RRC to zero */
}
if (conf_req_flag) {
code = krb5_c_crypto_length(context, enctype, KRB5_CRYPTO_TYPE_HEADER, &k5_headerlen);
if (code != 0)
goto cleanup;
theader->buffer.length += k5_headerlen; /* length validated later */
}
/* no PADDING for CFX, EC is used instead */
code = krb5_c_crypto_length(context, enctype,
conf_req_flag ? KRB5_CRYPTO_TYPE_TRAILER : KRB5_CRYPTO_TYPE_CHECKSUM,
&k5_trailerlen);
if (code != 0)
goto cleanup;
ttrailer->buffer.length = ec + (conf_req_flag ? 16 : 0 /* E(Header) */) + k5_trailerlen;
ttrailer->buffer.value = (unsigned char *)stream->buffer.value +
stream->buffer.length - ttrailer->buffer.length;
break;
}
case KG_TOK_MIC_MSG:
case KG_TOK_WRAP_MSG:
case KG_TOK_DEL_CTX:
theader->buffer.length += ctx->cksum_size +
kg_confounder_size(context, ctx->enc->keyblock.enctype);
/*
* we can't set the padding accurately until decryption;
* kg_fixup_padding_iov() will take care of this
*/
tpadding->buffer.length = 1;
tpadding->buffer.value = (unsigned char *)stream->buffer.value + stream->buffer.length - 1;
/* no TRAILER for pre-CFX */
ttrailer->buffer.length = 0;
ttrailer->buffer.value = NULL;
break;
default:
code = (OM_uint32)G_BAD_TOK_HEADER;
major_status = GSS_S_DEFECTIVE_TOKEN;
goto cleanup;
break;
}
/* IOV: -----------0-------------+---1---+--2--+----------------3--------------*/
/* Old: GSS-Header | Conf | Data | Pad | */
/* CFX: GSS-Header | Kerb-Header | Data | | EC | E(Header) | Kerb-Trailer */
/* GSS: -------GSS-HEADER--------+-DATA--+-PAD-+----------GSS-TRAILER----------*/
/* validate lengths */
if (stream->buffer.length < theader->buffer.length +
tpadding->buffer.length +
ttrailer->buffer.length)
{
code = (OM_uint32)KRB5_BAD_MSIZE;
major_status = GSS_S_DEFECTIVE_TOKEN;
goto cleanup;
}
/* setup data */
tdata->buffer.length = stream->buffer.length - ttrailer->buffer.length -
tpadding->buffer.length - theader->buffer.length;
assert(data != NULL);
if (data->type & GSS_IOV_BUFFER_FLAG_ALLOCATE) {
code = kg_allocate_iov(tdata, tdata->buffer.length);
if (code != 0)
goto cleanup;
memcpy(tdata->buffer.value,
(unsigned char *)stream->buffer.value + theader->buffer.length, tdata->buffer.length);
} else
tdata->buffer.value = (unsigned char *)stream->buffer.value + theader->buffer.length;
assert(i <= iov_count + 2);
major_status = kg_unseal_iov_token(&code, ctx, conf_state, qop_state,
tiov, i, toktype);
if (major_status == GSS_S_COMPLETE)
*data = *tdata;
else
kg_release_iov(tdata, 1);
cleanup:
if (tiov != NULL)
free(tiov);
*minor_status = code;
return major_status;
}
