.\" Automatically generated by Pod::Man 4.14 (Pod::Simple 3.40) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. 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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" TPMLIB_RegisterCallbacks \- Register callbacks for implementing customized behavior of certain functions .SH "LIBRARY" .IX Header "LIBRARY" \&\s-1TPM\s0 library (libtpms, \-ltpms) .SH "SYNOPSIS" .IX Header "SYNOPSIS" \&\fB#include .PP \&\fB#include .PP \&\fB#include .PP \&\fB\s-1TPM_RESULT\s0 TPMLIB_RegisterCallbacks(struct tpmlibrary_callbacks *);\fR .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \fB\fBTPMLIB_RegisterCallbacks()\fB\fR functions allows to register several callback functions with libtpms that enable a user to implement customized behavior of several library-internal functions. This feature will typically be used if the behavior of the provided internal functions is not as needed. An example would be that libtpms writes all data into files with certain names. If, however, the data needs to be written into a special type of storage the user will register callbacks with the library that are invoked when the \s-1TPM\s0 needs to write, read or delete data from storage and the user may then implement custom behavior in these functions. .PP The following shows the data structure used for registering the callbacks. .PP .Vb 10 \& struct libtpms_callbacks { \& int sizeOfStruct; \& TPM_RESULT (*tpm_nvram_init)(void); \& TPM_RESULT (*tpm_nvram_loaddata)(unsigned char **data, \& uint32_t *length, \& uint32_t tpm_number, \& const char *name); \& TPM_RESULT (*tpm_nvram_storedata)(const unsigned char *data, \& uint32_t length, \& uint32_t tpm_number, \& const char *name); \& TPM_RESULT (*tpm_nvram_deletename)(uint32_t tpm_number, \& const char *name, \& TPM_BOOL mustExist); \& TPM_RESULT (*tpm_io_init)(void); \& TPM_RESULT (*tpm_io_getlocality)(TPM_MODIFIER_INDICATOR *localityModifer, \& uint32_t tpm_number); \& TPM_RESULT (*tpm_io_getphysicalpresence)(TPM_BOOL *physicalPresence, \& uint32_t tpm_number); \& }; .Ve .PP Currently 7 callbacks are supported. If a callback pointer in the above structure is set to \s-1NULL\s0 the default library-internal implementation of that function will be used. .PP If one of the callbacks in either the \fItpm_nvram\fR or \fItpm_io\fR group is set, then all of the callbacks in the respective group should be implemented. .IP "\fBtpm_nvram_init\fR" 4 .IX Item "tpm_nvram_init" This function is called before any access to persitent storage is done. It allows the user to perform initialization of access to persitent storage. .Sp Upon success this function should return \fB\s-1TPM_SUCCESS\s0\fR, a failure code otherwise. .Sp The default implementation requires that the environment variable \&\fI\s-1TPM_PATH\s0\fR is set and points to a directory where the \s-1TPM\s0's state can be written to. If the variable is not set, it will return \fB\s-1TPM_FAIL\s0\fR and the initialization of the \s-1TPM\s0 in \fB\fBTPMLIB_MainInit()\fB\fR will fail. .IP "\fBtpm_nvram_loaddata\fR" 4 .IX Item "tpm_nvram_loaddata" This function is called when the \s-1TPM\s0 wants to load state from persistent storage. The implementing function must allocate a buffer (\fIdata\fR) and return it to the \s-1TPM\s0 along with the length of the buffer (\fIlength\fR). The \fItpm_number\fR is always 0 and can be ignored. The \fIname\fR parameter is either one of \fB\s-1TPM_SAVESTATE_NAME\s0\fR, \&\fB\s-1TPM_VOLATILESTATE_NAME\s0\fR, or \fB\s-1TPM_PERMANENT_ALL_NAME\s0\fR and indicates which one of the 3 types of state is supposed to be loaded. .Sp Upon success this function should return \fB\s-1TPM_SUCCESS\s0\fR, a failure code otherwise. .Sp The default implementation writes the \s-1TPM\s0's state into files in a directory where the \fI\s-1TPM_PATH\s0\fR environment variable pointed to when \&\fB\fBTPMLIB_MainInit()\fB\fR was executed. Failure to write the \s-1TPM\s0's state into files will put the \s-1TPM\s0 into failure mode. .Sp If this function is not set (\s-1NULL\s0), then the original NVChip file will be read when using a \s-1TPM 2.\s0 This file contains the memory dump of internal data structures and is neither portable between endianesses or architectures of different sizes (32 bit, 64 bit), nor will it allow handling extensions of those internal data structures it carries through additions in the \s-1TPM 2\s0 code. In the worst case this may result in memory access errors by internal functions and result in crashes. Therefore, it is recommended to set this function and handle the writing of the \s-1TPM\s0 state. .IP "\fBtpm_nvram_storedata\fR" 4 .IX Item "tpm_nvram_storedata" This function is called when the \s-1TPM\s0 wants to store state to persistent storage. The \fIdata\fR and \fIlength\fR parameters provide the data to be stored and the number of bytes. The implementing function must not free the \fIdata\fR buffer. The \fItpm_number\fR is always 0 and can be ignored. The \fIname\fR parameter is either one of \fB\s-1TPM_SAVESTATE_NAME\s0\fR, \&\fB\s-1TPM_VOLATILESTATE_NAME\s0\fR, or \fB\s-1TPM_PERMANENT_ALL_NAME\s0\fR and indicates which one of the 3 types of state is supposed to be stored. .Sp Upon success this function should return \fB\s-1TPM_SUCCESS\s0\fR, a failure code otherwise. .Sp The default implementation reads the \s-1TPM\s0's state from files in a directory where the \fI\s-1TPM_PATH\s0\fR environment variable pointed to when \&\fB\fBTPMLIB_MainInit()\fB\fR was executed. Failure to read the \s-1TPM\s0's state from files may put the \s-1TPM\s0 into failure mode. .Sp If this function is not set (\s-1NULL\s0), the memory dump will be written to the NVChip file (\s-1TPM 2\s0) and the same comments apply as when the \&\fItpm_nvram_loaddata\fR interface function is not set. .IP "\fBtpm_nvram_deletename\fR" 4 .IX Item "tpm_nvram_deletename" This function is called when the \s-1TPM\s0 wants to delete state on persistent storage. The \fItpm_number\fR is always 0 and can be ignored. The \fIname\fR parameter is either one of \fB\s-1TPM_SAVESTATE_NAME\s0\fR, \&\fB\s-1TPM_VOLATILESTATE_NAME\s0\fR, or \fB\s-1TPM_PERMANENT_ALL_NAME\s0\fR and indicates which one of the 3 types of state is supposed to be deleted. The \fImustExist\fR parameter indicates whether the given data must exist and the implementing function should return \fB\s-1TPM_FAIL\s0\fR if the data did not exist. .Sp Upon success this function should return \fB\s-1TPM_SUCCESS\s0\fR, a failure code otherwise. .Sp The default implementation deletes the \s-1TPM\s0's state files in a directory where the \fI\s-1TPM_PATH\s0\fR environment variable pointed to when \&\fB\fBTPMLIB_MainInit()\fB\fR was executed. Failure to delete the \s-1TPM\s0's state files may put the \s-1TPM\s0 into failure mode. .IP "\fBtpm_io_init\fR" 4 .IX Item "tpm_io_init" This function is called to initialize the \s-1IO\s0 subsystem of the \s-1TPM.\s0 .Sp Upon success this function should return \fB\s-1TPM_SUCCESS\s0\fR, a failure code otherwise. .Sp The default implementation simply returns \fB\s-1TPM_SUCCESS\s0\fR. .IP "\fBtpm_io_getlocality\fR" 4 .IX Item "tpm_io_getlocality" This function is called when the \s-1TPM\s0 needs to determine the locality under which a command is supposed to be executed. The implementing function should return the number of the locality by writing it into the \&\fBlocalityModifier\fR pointer. .Sp Upon success this function should return \fB\s-1TPM_SUCCESS\s0\fR, a failure code otherwise. .Sp The default implementation returns 0 as the locality. .IP "\fBtpm_io_getphysicalpresence\fR" 4 .IX Item "tpm_io_getphysicalpresence" This function is called when the \s-1TPM\s0 needs to determine whether physical presence has been asserted. The implementing function should write either \&\fB\s-1TRUE\s0\fR or \fB\s-1FALSE\s0\fR into the physicalPresence pointer. .Sp Upon success this function should return \fB\s-1TPM_SUCCESS\s0\fR, a failure code otherwise. .Sp The default implementation returns \fB\s-1FALSE\s0\fR for physical presence. .SH "RETURN VALUE" .IX Header "RETURN VALUE" Upon successful completion, \fB\fBTPMLIB_MainInit()\fB\fR returns \fB\s-1TPM_SUCCESS\s0\fR, an error value otherwise. .SH "ERRORS" .IX Header "ERRORS" .IP "\fB\s-1TPM_SUCCESS\s0\fR" 4 .IX Item "TPM_SUCCESS" The function completed successfully. .IP "\fB\s-1TPM_FAIL\s0\fR" 4 .IX Item "TPM_FAIL" General failure. .PP For a complete list of \s-1TPM\s0 error codes please consult the include file \&\fBlibtpms/tpm_error.h\fR .SH "EXAMPLE" .IX Header "EXAMPLE" .Vb 3 \& #include \& #include \& #include \& \& static TPM_MODIFIER_INDICATOR locality; \& \& static TPM_RESULT mytpm_io_init(void) \& { \& return TPM_SUCCESS; \& } \& \& static TPM_RESULT mytpm_io_getlocality(TPM_MODIFIER_INDICATOR *locModif, \& uint32_t tpm_number) \& { \& *locModif = locality; \& \& return TPM_SUCCESS: \& } \& \& static TPM_RESULT mytpm_io_getphysicalpresence(TPM_BOOL *physicalPresence, \& uint32_t tpm_number) \& { \& *physicalPresence = FALSE; \& \& return TPM_SUCCESS; \& } \& \& int main(void) { \& TPM_RESULT res; \& unsigned char *respbuffer; \& uint32_t resp_size; \& uint32_t respbufsize; \& unsigned char *command; \& uint32_t command_size; \& \& struct libtpms_callbacks cbs = { \& .sizeOfStruct = sizeof(struct libtpms_callbacks), \& .tpm_nvram_init = NULL, \& .tpm_nvram_loaddata = NULL, \& .tpm_nvram_storedata = NULL, \& .tpm_nvram_deletename = NULL, \& .tpm_io_init = mytpm_io_init, \& .tpm_io_getlocality = mytpm_io_getlocality, \& .tpm_io_getphysicalpresence = mytpm_io_getphysicalpresence, \& }; \& \& \& [...] \& \& if (TPMLIB_RegisterCallbacks(&cbs) != TPM_SUCCESS) { \& fprintf(stderr, "Could not register the callbacks.\en"); \& return 1; \& } \& \& if (TPMLIB_MainInit()) != TPM_SUCCESS) { \& fprintf(stderr, "Could not start the TPM.\en"); \& return 1; \& } \& \& [...] \& /* build TPM command */ \& [...] \& \& res = TPMLIB_Process(&respbuffer, &resp_size, \& &respbufsize, \& command, command_size); \& [...] \& \& TPMLIB_Terminate(); \& \& return 0; \& } .Ve .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBTPMLIB_Process\fR(3), \fBTPMLIB_MainInit\fR(3), \fBTPMLIB_Terminate\fR(3), \&\fBTPMLIB_DecodeBlobs\fR(3)