tpm2-tools源码分析之tpm2_createprimary.c(1)
TPM 2.0中的tpm2_createprimary命令对应的源文件就是tpm2_createprimary.c,该文件位于tpm2-tools/tools/下,一共有450行(版本5.5)。
tpm2_createprimary的功能是创建一个主密钥。命令描述为:此命令用于在以下层次结构之一下创建主对象:所有者、平台、背书、NULL。该命令将创建并加载主对象。敏感和公共部分不返回信息。已创建对象句柄的上下文文件保存为文件,以供将来与创建的主对象交互。
下边用几篇文章的篇幅对tpm2_createprimary.c文件结合tpm2_createprimary命令进行深入的、完全的解析。
先来看第一段代码:
// Register this tool with tpm2_tool.c
TPM2_TOOL_REGISTER("createprimary", tpm2_tool_onstart, tpm2_tool_onrun,tpm2_tool_onstop, tpm2_tool_onexit)
TPM2_TOOL_REGISTER是一个宏定义,在tpm2-tools/tools/tpm2_tool.h中,代码如下:
#define TPM2_TOOL_REGISTER(tool_name,tool_onstart,tool_onrun,tool_onstop,tool_onexit) \\static const tpm2_tool tool = { \\.name = tool_name, \\.onstart = tool_onstart, \\.onrun = tool_onrun, \\.onstop = tool_onstop, \\.onexit = tool_onexit, \\}; \\static void \\__attribute__((__constructor__)) \\__attribute__((__used__)) \\_tpm2_tool_init(void) \\{ \\tpm2_tool_register(&tool); \\}
TPM2_TOOLS_REGISTER宏定义是整个tpm2-tools中的命令所共用的,是一个框架性质的代码。
在本文件tpm2_createprimary.c也可以说tpm2_createprimary命令中,宏展开后为:
static const tpm2_tool tool = {.name = createprimary,.onstart = tool_onstart,.onrun = tool_onrun,.onstop = tool_onstop,.onexit = tool_onexit,
};
static void__attribute__((__constructor__))__attribute__((__used__))_tpm2_tool_init(void)
{tpm2_tool_register(&tool);
}
tpm2_tool结构的定义也在tpm2-tools/tools/tpm2_tool.h中,代码如下:
typedef struct {const char * name;tpm2_tool_onstart_t onstart;tpm2_tool_onrun_t onrun;tpm2_tool_onstop_t onstop;tpm2_tool_onexit_t onexit;
} tpm2_tool;
其中包含的相关函数指针如下(同文件中,就在上边):
/*** An optional interface for tools to specify what options they support.* They are concatenated with main's options and passed to getopt_long.* @param opts* The callee can choose to set *opts to a tpm_options pointer allocated* via tpm2_options_new(). Setting *opts to NULL is not an error, and* Indicates that no options are specified by the tool.** @return* True on success, false on error.*/
typedef bool (*tpm2_tool_onstart_t)(tpm2_options **opts);/*** This is the main interface for tools, after tcti and sapi/esapi initialization* are performed.* @param ectx* The system/esapi api context.* @param flags* Flags that tools may wish to respect.* @return* A tool_rc indicating status.*/
typedef tool_rc (*tpm2_tool_onrun_t)(ESYS_CONTEXT *ectx, tpm2_option_flags flags);/*** Called after tpm2_tool_onrun() is invoked. ESAPI context is still valid during this call.* @param ectx* The system/esapi api context.* @return* A tool_rc indicating status.*/
typedef tool_rc (*tpm2_tool_onstop_t)(ESYS_CONTEXT *ectx);/*** Called when the tool is exiting, useful for cleanup.*/
typedef void (*tpm2_tool_onexit_t)(void);
tpm2_tool_register函数在tpm2-tools/tools/tpm2_tools.c中实现,代码如下:
/** Build a list of the TPM2 tools linked into this executable*/
#ifndef TPM2_TOOLS_MAX
#define TPM2_TOOLS_MAX 1024
#endif
static const tpm2_tool *tools[TPM2_TOOLS_MAX];
static unsigned tool_count;void tpm2_tool_register(const tpm2_tool *tool) {if (tool_count < TPM2_TOOLS_MAX) {tools[tool_count++] = tool;} else {LOG_ERR("Over tool count");abort();}
}
回到tpm2_createprimary.c,来看具体的几个函数。
(1)tpm2_tool_onstart
tpm2_tool_onstart函数代码如下:
static bool tpm2_tool_onstart(tpm2_options **opts) {const struct option topts[] = {{ "hierarchy", required_argument, 0, 'C' },{ "hierarchy-auth", required_argument, 0, 'P' },{ "key-auth", required_argument, 0, 'p' },{ "hash-algorithm", required_argument, 0, 'g' },{ "key-algorithm", required_argument, 0, 'G' },{ "key-context", required_argument, 0, 'c' },{ "policy", required_argument, 0, 'L' },{ "attributes", required_argument, 0, 'a' },{ "unique-data", required_argument, 0, 'u' },{ "creation-data", required_argument, 0, 0 },{ "template-data", required_argument, 0, 1 },{ "creation-ticket",required_argument, 0, 't' },{ "creation-hash", required_argument, 0, 'd' },{ "outside-info", required_argument, 0, 'q' },{ "pcr-list", required_argument, 0, 'l' },{ "cphash", required_argument, 0, 2 },{ "format", required_argument, 0, 'f' },{ "output", required_argument, 0, 'o' },};*opts = tpm2_options_new("C:P:p:g:G:c:L:a:u:t:d:q:l:o:f:", ARRAY_LEN(topts),topts, on_option, 0, 0);return *opts != 0;
}
(2)tpm2_tool_onrun
tpm2_tool_onrun函数代码如下:
static tool_rc tpm2_tool_onrun(ESYS_CONTEXT *ectx, tpm2_option_flags flags) {UNUSED(flags);/** 1. Process options*/tool_rc rc = check_options(ectx);if (rc != tool_rc_success) {return rc;}/** 2. Process inputs*/rc = process_inputs(ectx);if (rc != tool_rc_success) {return rc;}/** 3. TPM2_CC_<command> call*/rc = createprimary(ectx);if (rc != tool_rc_success) {return rc;}/** 4. Process outputs*/return process_output(ectx);
}
(3)tpm2_tool_onstop
tpm2_tool_onstop函数代码如下:
static tool_rc tpm2_tool_onstop(ESYS_CONTEXT *ectx) {UNUSED(ectx);/** 1. Free objects*//** 2. Close authorization sessions*/tool_rc rc = tpm2_session_close(&ctx.auth_hierarchy.object.session);/** 3. Close auxiliary sessions*/return rc;
}
(4)tpm2_tool_onexit
tpm2_tool_onexit函数代码如下:
static void tpm2_tool_onexit(void) {tpm2_hierarchy_pdata_free(&ctx.objdata);
}
后续文章对这几个函数进行深入解析。