Re: [PATCH 4/4] stubdom/vtpm: Support multiple backends and locality

[Daniel De Graaf <dgdegra@tycho.nsa.gov>]

On 11/29/2012 02:09 PM, Matthew Fioravante wrote:
> Looks good. I'm actually kind of surprised that the emulator doesn't provide
> an interface to set the requested locality.

It does; however, it's a rather bad interface: you can send a vendor-specific
command to change the entire STANY_FLAGS data structure, which contains the
locality field along with some others that really shouldn't be changed. This
patch restricts that vendor-specific command interface to locality 8, which
can itself be restricted or unavailable once locality restrictions are
implemented. The number 8 was chosen because it's not usable as a quoting
locality since (1<<8) won't fit in uint8_t.
 
> Acked by: Matthew Fioravante <matthew.fioravante@jhuapl.edu>
> 
> On 11/27/2012 10:14 AM, Daniel De Graaf wrote:
>> The vTPM protocol now contains a field allowing the locality of a
>> command to be specified; pass this to the TPM when processing a packet.
>> This also enables a single vTPM to provide multiple tpmback interfaces
>> so that several closely related domains can share a vTPM (for example, a
>> qemu device stubdom and its target domain).
>>
>> Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
>> ---
>>   stubdom/tpmemu-0.7.4.patch | 61 ++++++++++++++++++++++++++++++++++++++++++----
>>   stubdom/vtpm/vtpm.c        | 16 +++---------
>>   2 files changed, 59 insertions(+), 18 deletions(-)
>>
>> diff --git a/stubdom/tpmemu-0.7.4.patch b/stubdom/tpmemu-0.7.4.patch
>> index b84eff1..31ace1a 100644
>> --- a/stubdom/tpmemu-0.7.4.patch
>> +++ b/stubdom/tpmemu-0.7.4.patch
>> @@ -1,9 +1,60 @@
>> -diff -Naur tpm_emulator-x86_64-back/tpm/tpm_emulator_extern.c tpm_emulator-x86_64/tpm/tpm_emulator_extern.c
>> ---- tpm_emulator-x86_64-back/tpm/tpm_emulator_extern.c    2012-04-27 10:55:46.581963398 -0400
>> -+++ tpm_emulator-x86_64/tpm/tpm_emulator_extern.c    2012-04-27 10:56:02.193034152 -0400
>> -@@ -249,7 +249,7 @@
>> +diff --git a/tpm/tpm_capability.c b/tpm/tpm_capability.c
>> +index 60bbb90..f8f7f0f 100644
>> +--- a/tpm/tpm_capability.c
>> ++++ b/tpm/tpm_capability.c
>> +@@ -949,6 +949,8 @@ static TPM_RESULT set_vendor(UINT32 subCap, BYTE *setValue,
>> +                              UINT32 setValueSize, BOOL ownerAuth,
>> +                              BOOL deactivated, BOOL disabled)
>> + {
>> ++  if (tpmData.stany.flags.localityModifier != 8)
>> ++    return TPM_BAD_PARAMETER;
>> +   /* set the capability area with the specified data, on failure
>> +      deactivate the TPM */
>> +   switch (subCap) {
>> +diff --git a/tpm/tpm_cmd_handler.c b/tpm/tpm_cmd_handler.c
>> +index 288d1ce..9e1cfb4 100644
>> +--- a/tpm/tpm_cmd_handler.c
>> ++++ b/tpm/tpm_cmd_handler.c
>> +@@ -4132,7 +4132,7 @@ void tpm_emulator_shutdown()
>> +   tpm_extern_release();
>> + }
>> +
>> +-int tpm_handle_command(const uint8_t *in, uint32_t in_size, uint8_t **out, uint32_t *out_size)
>> ++int tpm_handle_command(const uint8_t *in, uint32_t in_size, uint8_t **out, uint32_t *out_size, int locality)
>> + {
>> +   TPM_REQUEST req;
>> +   TPM_RESPONSE rsp;
>> +@@ -4140,7 +4140,9 @@ int tpm_handle_command(const uint8_t *in, uint32_t in_size, uint8_t **out, uint3
>> +   UINT32 len;
>> +   BOOL free_out;
>> +
>> +-  debug("tpm_handle_command()");
>> ++  debug("tpm_handle_command(%d)", locality);
>> ++  if (locality != -1)
>> ++    tpmData.stany.flags.localityModifier = locality;
>> +
>> +   /* we need the whole packet at once, otherwise unmarshalling will fail */
>> +   if (tpm_unmarshal_TPM_REQUEST((uint8_t**)&in, &in_size, &req) != 0) {
>> +diff --git a/tpm/tpm_emulator.h b/tpm/tpm_emulator.h
>> +index eed749e..4c228bd 100644
>> +--- a/tpm/tpm_emulator.h
>> ++++ b/tpm/tpm_emulator.h
>> +@@ -59,7 +59,7 @@ void tpm_emulator_shutdown(void);
>> +  * its usage. In case of an error, all internally allocated memory
>> +  * is released and the the state of out and out_size is unspecified.
>> +  */
>> +-int tpm_handle_command(const uint8_t *in, uint32_t in_size, uint8_t **out, uint32_t *out_size);
>> ++int tpm_handle_command(const uint8_t *in, uint32_t in_size, uint8_t **out, uint32_t *out_size, int locality);
>> +
>> + #endif /* _TPM_EMULATOR_H_ */
>> +
>> +diff --git a/tpm/tpm_emulator_extern.c b/tpm/tpm_emulator_extern.c
>> +index aabe6c3..440a01b 100644
>> +--- a/tpm/tpm_emulator_extern.c
>> ++++ b/tpm/tpm_emulator_extern.c
>> +@@ -249,7 +249,7 @@ int (*tpm_read_from_storage)(uint8_t **data, size_t *data_length) = _tpm_read_fr
>>    #else /* TPM_NO_EXTERN */
>> -
>> +
>>    int (*tpm_extern_init)(void)                                      = NULL;
>>   -int (*tpm_extern_release)(void)                                   = NULL;
>>   +void (*tpm_extern_release)(void)                                   = NULL;
>> diff --git a/stubdom/vtpm/vtpm.c b/stubdom/vtpm/vtpm.c
>> index c33e078..dcfc3b9 100644
>> --- a/stubdom/vtpm/vtpm.c
>> +++ b/stubdom/vtpm/vtpm.c
>> @@ -141,8 +141,6 @@ int check_ordinal(tpmcmd_t* tpmcmd) {
>>     static void main_loop(void) {
>>      tpmcmd_t* tpmcmd = NULL;
>> -   domid_t domid;        /* Domid of frontend */
>> -   unsigned int handle;    /* handle of frontend */
>>      int res = -1;
>>        info("VTPM Initializing\n");
>> @@ -162,15 +160,7 @@ static void main_loop(void) {
>>         goto abort_postpcrs;
>>      }
>>   -   /* Wait for the frontend domain to connect */
>> -   info("Waiting for frontend domain to connect..");
>> -   if(tpmback_wait_for_frontend_connect(&domid, &handle) == 0) {
>> -      info("VTPM attached to Frontend %u/%u", (unsigned int) domid, handle);
>> -   } else {
>> -      error("Unable to attach to a frontend");
>> -   }
>> -
>> -   tpmcmd = tpmback_req(domid, handle);
>> +   tpmcmd = tpmback_req_any();
>>      while(tpmcmd) {
>>         /* Handle the request */
>>         if(tpmcmd->req_len) {
>> @@ -183,7 +173,7 @@ static void main_loop(void) {
>>            }
>>            /* If not disabled, do the command */
>>            else {
>> -            if((res = tpm_handle_command(tpmcmd->req, tpmcmd->req_len, &tpmcmd->resp, &tpmcmd->resp_len)) != 0) {
>> +            if((res = tpm_handle_command(tpmcmd->req, tpmcmd->req_len, &tpmcmd->resp, &tpmcmd->resp_len, tpmcmd->locality)) != 0) {
>>                  error("tpm_handle_command() failed");
>>                  create_error_response(tpmcmd, TPM_FAIL);
>>               }
>> @@ -194,7 +184,7 @@ static void main_loop(void) {
>>         tpmback_resp(tpmcmd);
>>           /* Wait for the next request */
>> -      tpmcmd = tpmback_req(domid, handle);
>> +      tpmcmd = tpmback_req_any();
>>        }
>>   
> 
> 


-- 
Daniel De Graaf
National Security Agency