mirror of
https://github.com/yuzu-emu/unicorn.git
synced 2024-12-23 18:35:27 +00:00
484 lines
22 KiB
Plaintext
484 lines
22 KiB
Plaintext
This file documents the CAC (Common Access Card) library in the libcacard
|
|
subdirectory.
|
|
|
|
Virtual Smart Card Emulator
|
|
|
|
This emulator is designed to provide emulation of actual smart cards to a
|
|
virtual card reader running in a guest virtual machine. The emulated smart
|
|
cards can be representations of real smart cards, where the necessary functions
|
|
such as signing, card removal/insertion, etc. are mapped to real, physical
|
|
cards which are shared with the client machine the emulator is running on, or
|
|
the cards could be pure software constructs.
|
|
|
|
The emulator is structured to allow multiple replaceable or additional pieces,
|
|
so it can be easily modified for future requirements. The primary envisioned
|
|
modifications are:
|
|
|
|
1) The socket connection to the virtual card reader (presumably a CCID reader,
|
|
but other ISO-7816 compatible readers could be used). The code that handles
|
|
this is in vscclient.c.
|
|
|
|
2) The virtual card low level emulation. This is currently supplied by using
|
|
NSS. This emulation could be replaced by implementations based on other
|
|
security libraries, including but not limitted to openssl+pkcs#11 library,
|
|
raw pkcs#11, Microsoft CAPI, direct opensc calls, etc. The code that handles
|
|
this is in vcard_emul_nss.c.
|
|
|
|
3) Emulation for new types of cards. The current implementation emulates the
|
|
original DoD CAC standard with separate pki containers. This emulator lives in
|
|
cac.c. More than one card type emulator could be included. Other cards could
|
|
be emulated as well, including PIV, newer versions of CAC, PKCS #15, etc.
|
|
|
|
--------------------
|
|
Replacing the Socket Based Virtual Reader Interface.
|
|
|
|
The current implementation contains a replaceable module vscclient.c. The
|
|
current vscclient.c implements a sockets interface to the virtual ccid reader
|
|
on the guest. CCID commands that are pertinent to emulation are passed
|
|
across the socket, and their responses are passed back along that same socket.
|
|
The protocol that vscclient uses is defined in vscard_common.h and connects
|
|
to a qemu ccid usb device. Since this socket runs as a client, vscclient.c
|
|
implements a program with a main entry. It also handles argument parsing for
|
|
the emulator.
|
|
|
|
An application that wants to use the virtual reader can replace vscclient.c
|
|
with its own implementation that connects to its own CCID reader. The calls
|
|
that the CCID reader can call are:
|
|
|
|
VReaderList * vreader_get_reader_list();
|
|
|
|
This function returns a list of virtual readers. These readers may map to
|
|
physical devices, or simulated devices depending on vcard the back end. Each
|
|
reader in the list should represent a reader to the virtual machine. Virtual
|
|
USB address mapping is left to the CCID reader front end. This call can be
|
|
made any time to get an updated list. The returned list is a copy of the
|
|
internal list that can be referenced by the caller without locking. This copy
|
|
must be freed by the caller with vreader_list_delete when it is no longer
|
|
needed.
|
|
|
|
VReaderListEntry *vreader_list_get_first(VReaderList *);
|
|
|
|
This function gets the first entry on the reader list. Along with
|
|
vreader_list_get_next(), vreader_list_get_first() can be used to walk the
|
|
reader list returned from vreader_get_reader_list(). VReaderListEntries are
|
|
part of the list themselves and do not need to be freed separately from the
|
|
list. If there are no entries on the list, it will return NULL.
|
|
|
|
VReaderListEntry *vreader_list_get_next(VReaderListEntry *);
|
|
|
|
This function gets the next entry in the list. If there are no more entries
|
|
it will return NULL.
|
|
|
|
VReader * vreader_list_get_reader(VReaderListEntry *)
|
|
|
|
This function returns the reader stored in the reader List entry. Caller gets
|
|
a new reference to a reader. The caller must free its reference when it is
|
|
finished with vreader_free().
|
|
|
|
void vreader_free(VReader *reader);
|
|
|
|
This function frees a reference to a reader. Readers are reference counted
|
|
and are automatically deleted when the last reference is freed.
|
|
|
|
void vreader_list_delete(VReaderList *list);
|
|
|
|
This function frees the list, all the elements on the list, and all the
|
|
reader references held by the list.
|
|
|
|
VReaderStatus vreader_power_on(VReader *reader, char *atr, int *len);
|
|
|
|
This function simulates a card power on. A virtual card does not care about
|
|
the actual voltage and other physical parameters, but it does care that the
|
|
card is actually on or off. Cycling the card causes the card to reset. If
|
|
the caller provides enough space, vreader_power_on will return the ATR of
|
|
the virtual card. The amount of space provided in atr should be indicated
|
|
in *len. The function modifies *len to be the actual length of of the
|
|
returned ATR.
|
|
|
|
VReaderStatus vreader_power_off(VReader *reader);
|
|
|
|
This function simulates a power off of a virtual card.
|
|
|
|
VReaderStatus vreader_xfer_bytes(VReader *reader, unsigne char *send_buf,
|
|
int send_buf_len,
|
|
unsigned char *receive_buf,
|
|
int receive_buf_len);
|
|
|
|
This function sends a raw apdu to a card and returns the card's response.
|
|
The CCID front end should return the response back. Most of the emulation
|
|
is driven from these APDUs.
|
|
|
|
VReaderStatus vreader_card_is_present(VReader *reader);
|
|
|
|
This function returns whether or not the reader has a card inserted. The
|
|
vreader_power_on, vreader_power_off, and vreader_xfer_bytes will return
|
|
VREADER_NO_CARD.
|
|
|
|
const char *vreader_get_name(VReader *reader);
|
|
|
|
This function returns the name of the reader. The name comes from the card
|
|
emulator level and is usually related to the name of the physical reader.
|
|
|
|
VReaderID vreader_get_id(VReader *reader);
|
|
|
|
This function returns the id of a reader. All readers start out with an id
|
|
of -1. The application can set the id with vreader_set_id.
|
|
|
|
VReaderStatus vreader_get_id(VReader *reader, VReaderID id);
|
|
|
|
This function sets the reader id. The application is responsible for making
|
|
sure that the id is unique for all readers it is actively using.
|
|
|
|
VReader *vreader_find_reader_by_id(VReaderID id);
|
|
|
|
This function returns the reader which matches the id. If two readers match,
|
|
only one is returned. The function returns NULL if the id is -1.
|
|
|
|
Event *vevent_wait_next_vevent();
|
|
|
|
This function blocks waiting for reader and card insertion events. There
|
|
will be one event for each card insertion, each card removal, each reader
|
|
insertion and each reader removal. At start up, events are created for all
|
|
the initial readers found, as well as all the cards that are inserted.
|
|
|
|
Event *vevent_get_next_vevent();
|
|
|
|
This function returns a pending event if it exists, otherwise it returns
|
|
NULL. It does not block.
|
|
|
|
----------------
|
|
Card Type Emulator: Adding a New Virtual Card Type
|
|
|
|
The ISO 7816 card spec describes 2 types of cards:
|
|
1) File system cards, where the smartcard is managed by reading and writing
|
|
data to files in a file system. There is currently only boiler plate
|
|
implemented for file system cards.
|
|
2) VM cards, where the card has loadable applets which perform the card
|
|
functions. The current implementation supports VM cards.
|
|
|
|
In the case of VM cards, the difference between various types of cards is
|
|
really what applets have been installed in that card. This structure is
|
|
mirrored in card type emulators. The 7816 emulator already handles the basic
|
|
ISO 7186 commands. Card type emulators simply need to add the virtual applets
|
|
which emulate the real card applets. Card type emulators have exactly one
|
|
public entry point:
|
|
|
|
VCARDStatus xxx_card_init(VCard *card, const char *flags,
|
|
const unsigned char *cert[],
|
|
int cert_len[],
|
|
VCardKey *key[],
|
|
int cert_count);
|
|
|
|
The parameters for this are:
|
|
card - the virtual card structure which will represent this card.
|
|
flags - option flags that may be specific to this card type.
|
|
cert - array of binary certificates.
|
|
cert_len - array of lengths of each of the certificates specified in cert.
|
|
key - array of opaque key structures representing the private keys on
|
|
the card.
|
|
cert_count - number of entries in cert, cert_len, and key arrays.
|
|
|
|
Any cert, cert_len, or key with the same index are matching sets. That is
|
|
cert[0] is cert_len[0] long and has the corresponding private key of key[0].
|
|
|
|
The card type emulator is expected to own the VCardKeys, but it should copy
|
|
any raw cert data it wants to save. It can create new applets and add them to
|
|
the card using the following functions:
|
|
|
|
VCardApplet *vcard_new_applet(VCardProcessAPDU apdu_func,
|
|
VCardResetApplet reset_func,
|
|
const unsigned char *aid,
|
|
int aid_len);
|
|
|
|
This function creates a new applet. Applet structures store the following
|
|
information:
|
|
1) the AID of the applet (set by aid and aid_len).
|
|
2) a function to handle APDUs for this applet. (set by apdu_func, more on
|
|
this below).
|
|
3) a function to reset the applet state when the applet is selected.
|
|
(set by reset_func, more on this below).
|
|
3) applet private data, a data pointer used by the card type emulator to
|
|
store any data or state it needs to complete requests. (set by a
|
|
separate call).
|
|
4) applet private data free, a function used to free the applet private
|
|
data when the applet itself is destroyed.
|
|
The created applet can be added to the card with vcard_add_applet below.
|
|
|
|
void vcard_set_applet_private(VCardApplet *applet,
|
|
VCardAppletPrivate *private,
|
|
VCardAppletPrivateFree private_free);
|
|
This function sets the private data and the corresponding free function.
|
|
VCardAppletPrivate is an opaque data structure to the rest of the emulator.
|
|
The card type emulator can define it any way it wants by defining
|
|
struct VCardAppletPrivateStruct {};. If there is already a private data
|
|
structure on the applet, the old one is freed before the new one is set up.
|
|
passing two NULL clear any existing private data.
|
|
|
|
VCardStatus vcard_add_applet(VCard *card, VCardApplet *applet);
|
|
|
|
Add an applet onto the list of applets attached to the card. Once an applet
|
|
has been added, it can be selected by its AID, and then commands will be
|
|
routed to it VCardProcessAPDU function. This function adopts the applet that
|
|
is passed into it. Note: 2 applets with the same AID should not be added to
|
|
the same card. It is permissible to add more than one applet. Multiple applets
|
|
may have the same VCardPRocessAPDU entry point.
|
|
|
|
The certs and keys should be attached to private data associated with one or
|
|
more appropriate applets for that card. Control will come to the card type
|
|
emulators once one of its applets are selected through the VCardProcessAPDU
|
|
function it specified when it created the applet.
|
|
|
|
The signature of VCardResetApplet is:
|
|
VCardStatus (*VCardResetApplet) (VCard *card, int channel);
|
|
This function will reset the any internal applet state that needs to be
|
|
cleared after a select applet call. It should return VCARD_DONE;
|
|
|
|
The signature of VCardProcessAPDU is:
|
|
VCardStatus (*VCardProcessAPDU)(VCard *card, VCardAPDU *apdu,
|
|
VCardResponse **response);
|
|
This function examines the APDU and determines whether it should process
|
|
the apdu directly, reject the apdu as invalid, or pass the apdu on to
|
|
the basic 7816 emulator for processing.
|
|
If the 7816 emulator should process the apdu, then the VCardProcessAPDU
|
|
should return VCARD_NEXT.
|
|
If there is an error, then VCardProcessAPDU should return an error
|
|
response using vcard_make_response and the appropriate 7816 error code
|
|
(see card_7816t.h) or vcard_make_response with a card type specific error
|
|
code. It should then return VCARD_DONE.
|
|
If the apdu can be processed correctly, VCardProcessAPDU should do so,
|
|
set the response value appropriately for that APDU, and return VCARD_DONE.
|
|
VCardProcessAPDU should always set the response if it returns VCARD_DONE.
|
|
It should always either return VCARD_DONE or VCARD_NEXT.
|
|
|
|
Parsing the APDU --
|
|
|
|
Prior to processing calling the card type emulator's VCardProcessAPDU function, the emulator has already decoded the APDU header and set several fields:
|
|
|
|
apdu->a_data - The raw apdu data bytes.
|
|
apdu->a_len - The len of the raw apdu data.
|
|
apdu->a_body - The start of any post header parameter data.
|
|
apdu->a_Lc - The parameter length value.
|
|
apdu->a_Le - The expected length of any returned data.
|
|
apdu->a_cla - The raw apdu class.
|
|
apdu->a_channel - The channel (decoded from the class).
|
|
apdu->a_secure_messaging_type - The decoded secure messaging type
|
|
(from class).
|
|
apdu->a_type - The decode class type.
|
|
apdu->a_gen_type - the generic class type (7816, PROPRIETARY, RFU, PTS).
|
|
apdu->a_ins - The instruction byte.
|
|
apdu->a_p1 - Parameter 1.
|
|
apdu->a_p2 - Parameter 2.
|
|
|
|
Creating a Response --
|
|
|
|
The expected result of any APDU call is a response. The card type emulator must
|
|
set *response with an appropriate VCardResponse value if it returns VCARD_DONE.
|
|
Responses could be as simple as returning a 2 byte status word response, to as
|
|
complex as returning a block of data along with a 2 byte response. Which is
|
|
returned will depend on the semantics of the APDU. The following functions will
|
|
create card responses.
|
|
|
|
VCardResponse *vcard_make_response(VCard7816Status status);
|
|
|
|
This is the most basic function to get a response. This function will
|
|
return a response the consists solely one 2 byte status code. If that status
|
|
code is defined in card_7816t.h, then this function is guaranteed to
|
|
return a response with that status. If a cart type specific status code
|
|
is passed and vcard_make_response fails to allocate the appropriate memory
|
|
for that response, then vcard_make_response will return a VCardResponse
|
|
of VCARD7816_STATUS_EXC_ERROR_MEMORY. In any case, this function is
|
|
guaranteed to return a valid VCardResponse.
|
|
|
|
VCardResponse *vcard_response_new(unsigned char *buf, int len,
|
|
VCard7816Status status);
|
|
|
|
This function is similar to vcard_make_response except it includes some
|
|
returned data with the response. It could also fail to allocate enough
|
|
memory, in which case it will return NULL.
|
|
|
|
VCardResponse *vcard_response_new_status_bytes(unsigned char sw1,
|
|
unsigned char sw2);
|
|
|
|
Sometimes in 7816 the response bytes are treated as two separate bytes with
|
|
split meanings. This function allows you to create a response based on
|
|
two separate bytes. This function could fail, in which case it will return
|
|
NULL.
|
|
|
|
VCardResponse *vcard_response_new_bytes(unsigned char *buf, int len,
|
|
unsigned char sw1,
|
|
unsigned char sw2);
|
|
|
|
This function is the same as vcard_response_new except you may specify
|
|
the status as two separate bytes like vcard_response_new_status_bytes.
|
|
|
|
|
|
Implementing functionality ---
|
|
|
|
The following helper functions access information about the current card
|
|
and applet.
|
|
|
|
VCARDAppletPrivate *vcard_get_current_applet_private(VCard *card,
|
|
int channel);
|
|
|
|
This function returns any private data set by the card type emulator on
|
|
the currently selected applet. The card type emulator keeps track of the
|
|
current applet state in this data structure. Any certs and keys associated
|
|
with a particular applet is also stored here.
|
|
|
|
int vcard_emul_get_login_count(VCard *card);
|
|
|
|
This function returns the the number of remaining login attempts for this
|
|
card. If the card emulator does not know, or the card does not have a
|
|
way of giving this information, this function returns -1.
|
|
|
|
|
|
VCard7816Status vcard_emul_login(VCard *card, unsigned char *pin,
|
|
int pin_len);
|
|
|
|
This function logs into the card and returns the standard 7816 status
|
|
word depending on the success or failure of the call.
|
|
|
|
void vcard_emul_delete_key(VCardKey *key);
|
|
|
|
This function frees the VCardKey passed in to xxxx_card_init. The card
|
|
type emulator is responsible for freeing this key when it no longer needs
|
|
it.
|
|
|
|
VCard7816Status vcard_emul_rsa_op(VCard *card, VCardKey *key,
|
|
unsigned char *buffer,
|
|
int buffer_size);
|
|
|
|
This function does a raw rsa op on the buffer with the given key.
|
|
|
|
The sample card type emulator is found in cac.c. It implements the cac specific
|
|
applets. Only those applets needed by the coolkey pkcs#11 driver on the guest
|
|
have been implemented. To support the full range CAC middleware, a complete CAC
|
|
card according to the CAC specs should be implemented here.
|
|
|
|
------------------------------
|
|
Virtual Card Emulator
|
|
|
|
This code accesses both real smart cards and simulated smart cards through
|
|
services provided on the client. The current implementation uses NSS, which
|
|
already knows how to talk to various PKCS #11 modules on the client, and is
|
|
portable to most operating systems. A particular emulator can have only one
|
|
virtual card implementation at a time.
|
|
|
|
The virtual card emulator consists of a series of virtual card services. In
|
|
addition to the services describe above (services starting with
|
|
vcard_emul_xxxx), the virtual card emulator also provides the following
|
|
functions:
|
|
|
|
VCardEmulError vcard_emul_init(cont VCardEmulOptions *options);
|
|
|
|
The options structure is built by another function in the virtual card
|
|
interface where a string of virtual card emulator specific strings are
|
|
mapped to the options. The actual structure is defined by the virtual card
|
|
emulator and is used to determine the configuration of soft cards, or to
|
|
determine which physical cards to present to the guest.
|
|
|
|
The vcard_emul_init function will build up sets of readers, create any
|
|
threads that are needed to watch for changes in the reader state. If readers
|
|
have cards present in them, they are also initialized.
|
|
|
|
Readers are created with the function.
|
|
|
|
VReader *vreader_new(VReaderEmul *reader_emul,
|
|
VReaderEmulFree reader_emul_free);
|
|
|
|
The freeFunc is used to free the VReaderEmul * when the reader is
|
|
destroyed. The VReaderEmul structure is an opaque structure to the
|
|
rest of the code, but defined by the virtual card emulator, which can
|
|
use it to store any reader specific state.
|
|
|
|
Once the reader has been created, it can be added to the front end with the
|
|
call:
|
|
|
|
VReaderStatus vreader_add_reader(VReader *reader);
|
|
|
|
This function will automatically generate the appropriate new reader
|
|
events and add the reader to the list.
|
|
|
|
To create a new card, the virtual card emulator will call a similar
|
|
function.
|
|
|
|
VCard *vcard_new(VCardEmul *card_emul,
|
|
VCardEmulFree card_emul_free);
|
|
|
|
Like vreader_new, this function takes a virtual card emulator specific
|
|
structure which it uses to keep track of the card state.
|
|
|
|
Once the card is created, it is attached to a card type emulator with the
|
|
following function:
|
|
|
|
VCardStatus vcard_init(VCard *vcard, VCardEmulType type,
|
|
const char *flags,
|
|
unsigned char *const *certs,
|
|
int *cert_len,
|
|
VCardKey *key[],
|
|
int cert_count);
|
|
|
|
The vcard is the value returned from vcard_new. The type is the
|
|
card type emulator that this card should presented to the guest as.
|
|
The flags are card type emulator specific options. The certs,
|
|
cert_len, and keys are all arrays of length cert_count. These are the
|
|
the same of the parameters xxxx_card_init() accepts.
|
|
|
|
Finally the card is associated with its reader by the call:
|
|
|
|
VReaderStatus vreader_insert_card(VReader *vreader, VCard *vcard);
|
|
|
|
This function, like vreader_add_reader, will take care of any event
|
|
notification for the card insert.
|
|
|
|
|
|
VCardEmulError vcard_emul_force_card_remove(VReader *vreader);
|
|
|
|
Force a card that is present to appear to be removed to the guest, even if
|
|
that card is a physical card and is present.
|
|
|
|
|
|
VCardEmulError vcard_emul_force_card_insert(VReader *reader);
|
|
|
|
Force a card that has been removed by vcard_emul_force_card_remove to be
|
|
reinserted from the point of view of the guest. This will only work if the
|
|
card is physically present (which is always true fro a soft card).
|
|
|
|
void vcard_emul_get_atr(Vcard *card, unsigned char *atr, int *atr_len);
|
|
|
|
Return the virtual ATR for the card. By convention this should be the value
|
|
VCARD_ATR_PREFIX(size) followed by several ascii bytes related to this
|
|
particular emulator. For instance the NSS emulator returns
|
|
{VCARD_ATR_PREFIX(3), 'N', 'S', 'S' }. Do ot return more data then *atr_len;
|
|
|
|
void vcard_emul_reset(VCard *card, VCardPower power)
|
|
|
|
Set the state of 'card' to the current power level and reset its internal
|
|
state (logout, etc).
|
|
|
|
-------------------------------------------------------
|
|
List of files and their function:
|
|
README - This file
|
|
card_7816.c - emulate basic 7816 functionality. Parse APDUs.
|
|
card_7816.h - apdu and response services definitions.
|
|
card_7816t.h - 7816 specific structures, types and definitions.
|
|
event.c - event handling code.
|
|
event.h - event handling services definitions.
|
|
eventt.h - event handling structures and types
|
|
vcard.c - handle common virtual card services like creation, destruction, and
|
|
applet management.
|
|
vcard.h - common virtual card services function definitions.
|
|
vcardt.h - comon virtual card types
|
|
vreader.c - common virtual reader services.
|
|
vreader.h - common virtual reader services definitions.
|
|
vreadert.h - comon virtual reader types.
|
|
vcard_emul_type.c - manage the card type emulators.
|
|
vcard_emul_type.h - definitions for card type emulators.
|
|
cac.c - card type emulator for CAC cards
|
|
vcard_emul.h - virtual card emulator service definitions.
|
|
vcard_emul_nss.c - virtual card emulator implementation for nss.
|
|
vscclient.c - socket connection to guest qemu usb driver.
|
|
vscard_common.h - common header with the guest qemu usb driver.
|
|
mutex.h - header file for machine independent mutexes.
|
|
link_test.c - static test to make sure all the symbols are properly defined.
|