mirror of
https://gitlab.com/cryptsetup/cryptsetup.git
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Add some examples. (thanks to okozina)
git-svn-id: https://cryptsetup.googlecode.com/svn/trunk@618 36d66b0a-2a48-0410-832c-cd162a569da5
This commit is contained in:
Milan Broz
20
docs/examples/crypt_examples.h
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20
docs/examples/crypt_examples.h
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@@ -0,0 +1,20 @@
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#define EX_STEP(step_nr, format, args...) do { \
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printf("STEP_%02d: Entering "format"... ", step_nr, ##args); \
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} while(0)
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#define EX_FAIL(format, args...) do { \
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printf("FAIL\n"); \
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fprintf(stderr, "\t"format"\n", ##args); \
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} while(0)
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#define EX_SUCCESS(format, args...) do { \
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printf("OK\n\t"format"\n", ##args); \
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} while(0)
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#define EX_DELIM printf("-------------------------------\n")
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#define EX_PRESS_ENTER(msg, args...) do { \
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printf(msg "\nPress <ENTER> to continue: ", ##args); \
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getc(stdin); \
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} while(0)
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98
docs/examples/crypt_log_usage.c
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98
docs/examples/crypt_log_usage.c
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#include <libcryptsetup.h>
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#include <syslog.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "crypt_examples.h"
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#define LOG_PREFIX_CD "cslog_example_prefix"
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int log_ready = 0;
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/*
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* This is an example of function that can be registered using crypt_set_log_callback API.
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*
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* Its prototype is void (*log)(int level, const char *msg, void *usrptr) as defined
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* in crypt_set_log_callback
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*
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* NOTE: that some syslog message levels may not be visible with respect to your
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* syslog setings
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*
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* If your syslog daemon is turned off, messages should be printed to stderr
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*/
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static void simple_syslog_wrapper(int level, const char *msg, void *usrptr)
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{
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if(!log_ready) {
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openlog((char *)usrptr, LOG_CONS | LOG_PID, LOG_USER);
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log_ready = 1;
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}
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switch(level) {
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case CRYPT_LOG_NORMAL:
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syslog(LOG_NOTICE, msg);
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break;
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case CRYPT_LOG_ERROR:
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syslog(LOG_ERR, msg);
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break;
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case CRYPT_LOG_VERBOSE:
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syslog(LOG_INFO, msg);
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break;
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case CRYPT_LOG_DEBUG:
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syslog(LOG_DEBUG, msg);
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break;
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default:
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fprintf(stderr, "Unsupported log level requested!\n");
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}
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}
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int main(void)
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{
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int step = 0, r = 0;
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struct crypt_device *cd;
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if (geteuid())
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fprintf(stderr, "WARN: Process doesn't have super user privileges. "
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"Most of examples will fail because of that.\n");
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EX_STEP(++step, "crypt_init() to get an empty device context");
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if ((r = crypt_init(&cd, NULL))) {
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EX_FAIL("crypt_init() failed.");
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return r;
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}
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EX_SUCCESS("crypt_init() successfull");
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EX_STEP(++step, "crypt_set_log_callback() to register a log function tied with context");
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crypt_set_log_callback(cd, &simple_syslog_wrapper, LOG_PREFIX_CD);
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EX_SUCCESS("");
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EX_DELIM;
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EX_STEP(++step, "multiple crypt_log() to send messages into the context set log function. "
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"The messages should be prefixed with '" LOG_PREFIX_CD "'");
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crypt_log(cd, CRYPT_LOG_NORMAL, "This is normal log message");
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crypt_log(cd, CRYPT_LOG_ERROR, "This is error log message");
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crypt_log(cd, CRYPT_LOG_VERBOSE, "This is verbose log message");
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crypt_log(cd, CRYPT_LOG_DEBUG, "This is debug message");
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EX_SUCCESS("");
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EX_DELIM;
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crypt_free(cd);
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if (log_ready)
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closelog();
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log_ready = 0;
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EX_STEP(++step, "crypt_set_log_callback() to register a default (global) log function");
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crypt_set_log_callback(NULL, &simple_syslog_wrapper, NULL);
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EX_SUCCESS("");
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EX_DELIM;
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EX_STEP(++step, "multiple crypt_log() to send messages into default log");
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crypt_log(NULL, CRYPT_LOG_NORMAL, "This is normal log message");
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crypt_log(NULL, CRYPT_LOG_ERROR, "This is error log message");
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crypt_log(NULL, CRYPT_LOG_VERBOSE, "This is verbose log message");
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crypt_log(NULL, CRYPT_LOG_DEBUG, "This is debug message");
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EX_SUCCESS("");
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return r;
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}
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306
docs/examples/crypt_luks_usage.c
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306
docs/examples/crypt_luks_usage.c
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@@ -0,0 +1,306 @@
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#include <inttypes.h>
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#include <libcryptsetup.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "crypt_examples.h"
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#define KEY_SIZE 32
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#define EX_DEV_NAME "ex_crypt_dev"
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#define DMDIR "/dev/mapper/"
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#define SECTOR_SIZE 512
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/*
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* You can use this example with command line parameters as follows,
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* but please note, that this example will not do any sophisticated parameters
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* checking at all.
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*
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* ./crypt_luks_usage <path>
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*
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* where:
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* <path> is either regular file or block device. DO NOT use your physical HDD
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* with running system or another device containing valuable data otherwise you risk
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* partial or complete loss of it.
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*/
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static void usage(const char *msg)
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{
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fprintf(stderr, "ERROR: %s\nusage: ./crypt_luks_usage <path>\n"
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"The <path> can refer to either a regular file or a block device.\n",
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msg ?: "");
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}
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int main(int argc, char **argv)
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{
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char *answer = NULL, *cipher, *cipher_mode, *dev;
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int step = 0, r;
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size_t size = 0;
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/* crypt device handle */
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struct crypt_active_device cad;
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struct crypt_device *cd;
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struct crypt_params_luks1 params;
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if (geteuid())
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fprintf(stderr, "WARN: Process doesn't have super user privileges. "
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"Most of examples will fail because of that.\n");
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if (argc != 2) {
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usage("Wrong number of cmd line parameters.");
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exit(1);
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}
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dev = argv[1];
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/*
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* __STEP_01__
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*
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* crypt_init() call precedes most of operations of cryptsetup API. The call is used
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* to initialize crypt device context stored in structure referenced by _cd_ in
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* the example. Second parameter is used to pass underlaying device path.
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*
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* Note:
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* If path refers to a regular file it'll be attached to a first free loop device.
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* crypt_init() operation fails in case there's no more loop device available.
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* Also, loop device will have the AUTOCLEAR flag set, so the file will be
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* detached after crypt_free() call on the concerned context.
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*/
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EX_STEP(++step, "crypt_init()");
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if ((r = crypt_init(&cd, dev))) {
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EX_FAIL("crypt_init() failed for '%s'\n", dev ?: "(not set)");
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return r;
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}
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EX_SUCCESS("crypt_init() on '%s' has been successful", dev);
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if (strcmp(dev, crypt_get_device_name(cd)))
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printf("\tFile '%s' has been attached to %s\n", dev, crypt_get_device_name(cd));
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EX_DELIM;
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/*
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* So far no data were written on your device. This will change with call of
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* crypt_format() only if you specify CRYPT_LUKS1 as device type.
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*/
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printf("8 initial sectors of the device will be overwritten\n"
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"Are you sure you want to call crypt_format() over '%s'?\n"
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"If you're absolutely sure the device doesn't contain any valuable data,\n"
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"approve the operation by typing 'yes' in upper case: ", crypt_get_device_name(cd));
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if ((r = getline(&answer, &size, stdin)) == -1) {
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perror("getline");
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goto out;
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}
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if (strcmp(answer, "YES\n"))
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goto out;
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/* Example of crypt_format() follows: */
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/*
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* cipher and cipher_mode:
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*
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* you'll get more on _cipher_ and _cipher_mode_ in man page
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* for cryptsetup userspace utility or at cryptsetup project
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* documentation.
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*/
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cipher = "aes";
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cipher_mode = "cbc-essiv:sha256";
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params.hash = "sha1";
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/*
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* This parameter is relevant only in case of the luks header
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* and the payload are both stored on same device.
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*
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* In this particular case, payload offset (which is
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* computed internaly, according to volume key size)
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* is aligned to 2048 sectors
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*
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* if you set data_alignment = 0, cryptsetup will autodetect
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* data_alignment from underlaying device topology.
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*/
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params.data_alignment = 2048;
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/*
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* this parameter defines that no external device
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* for luks header will be used
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*/
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params.data_device = NULL;
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/*
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* __STEP_02__
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*
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* NULLs for uuid and volume_key means that these attributes will be
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* generated during crypt_format(). Volume key is generated with respect
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* to key size parameter passed to function.
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*
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* Note that in crypt_format() device is checked wheter it's large enough to
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* store the luks header only.
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*/
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EX_STEP(++step, "crypt_format()");
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if((r = crypt_format(cd, CRYPT_LUKS1, cipher, cipher_mode, NULL, NULL, KEY_SIZE, ¶ms))) {
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EX_FAIL("crypt_format() failed on device %s\n", crypt_get_device_name(cd));
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goto out;
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}
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EX_SUCCESS("crypt_format() on device %s formated successfully. "
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"The device now contains LUKS1 header, but there is no active keyslot with encrypted "
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"volume key.", crypt_get_device_name(cd));
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EX_DELIM;
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/*
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* __STEP_03__
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*
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* This call is intended to store volume_key in encrypted form into structure called keyslot.
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* Without keyslot you can't manipulate with LUKS device after the context will be freed.
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*
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* To create a new keyslot you need to supply the existing one (to get the volume key from) or
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* you need to supply the volume key. Now we have volume key stored internally and we have no active
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* keyslot so this the only option.
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*
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*/
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printf("Going to create a new keyslot...\n");
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EX_STEP(++step, "crypt_keyslot_add_by_volume_key()");
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if ((r = crypt_keyslot_add_by_volume_key(cd, CRYPT_ANY_SLOT, NULL, 0, NULL, 0)) < 0) {
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EX_FAIL("Adding keyslot failed.");
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goto out;
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}
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EX_SUCCESS("Keyslot nr. %d created successfully on device %s.", r, crypt_get_device_name(cd));
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EX_DELIM;
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/*
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* __STEP_04__
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*
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* This is the example of the second method mentioned in STEP 03. By supplying passphrase for
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* the active keyslot you can create a new one.
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*/
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printf("Now let's try to add a keyslot using the existing active keyslot\n");
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EX_STEP(++step, "crypt_keyslot_add_by_passphrase()");
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if ((r = crypt_keyslot_add_by_passphrase(cd, CRYPT_ANY_SLOT, NULL, 0, NULL, 0)) < 0) {
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EX_FAIL("Adding keyslot failed\n");
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goto out;
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}
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EX_SUCCESS("Keyslot nr. %d created successfully and written on device %s.", r, crypt_get_device_name(cd));
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EX_DELIM;
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crypt_free(cd);
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cd = NULL;
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/*
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* __STEP_05__
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*
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* In previous steps the device was formatted (LUKS header was written to backing device)
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* and keyslots were activated (volume key was written in two separate structures encrypted
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* by two user supplied passwords).
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*
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* This example demonstrates typical use case for LUKS device activation.
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* It's sequence of sub-steps: device initialization (crypt_init), LUKS header load (crypt_load())
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* and finally the device activation itself
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*/
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EX_PRESS_ENTER("Device context going to be freed. New one will initialized to demonstrate activation process.");
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EX_STEP(++step, "crypt_init()");
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if ((r = crypt_init(&cd, dev))) {
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EX_FAIL("crypt_init() failed for '%s'!", dev);
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goto out;
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}
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EX_SUCCESS("crypt_init() on '%s' has been successful.", dev);
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if (strcmp(dev, crypt_get_device_name(cd)))
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printf("\tFile '%s' has been attached to %s\n", dev, crypt_get_device_name(cd));
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EX_DELIM;
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/* __STEP_05__
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*
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* crypt_load() is used to load the LUKS header from backing block device
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* into crypt_device context
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*/
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EX_PRESS_ENTER("Going to load LUKS header.");
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EX_STEP(step, "crypt_load()");
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if ((r = crypt_load(cd, CRYPT_LUKS1, ¶ms))) {
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EX_FAIL("crypt_load() failed on device '%s'!", crypt_get_device_name(cd));
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goto out;
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}
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EX_SUCCESS("crypt_load() successful. The header has been read from %s.", crypt_get_device_name(cd));
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EX_DELIM;
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/*
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* __STEP_05__
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*
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* Device activation creates mapping in device-mapper with name EX_DEV_NAME.
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* The volume key is stored into kernel mem. space and the encryption of backing
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* device is now set in motion.
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*/
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printf("Going to activate LUKS device\n");
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EX_STEP(step, "crypt_activate_by_passphrase()");
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if ((r = crypt_activate_by_passphrase(cd, EX_DEV_NAME, CRYPT_ANY_SLOT, NULL, 0, 0)) < 0) {
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EX_FAIL("Device activation failed!");
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goto out;
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}
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EX_SUCCESS("Encrypted device is active on " DMDIR EX_DEV_NAME ".");
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printf("\tThe cipher used in device context: '%s'\n", crypt_get_cipher(cd) ?: "(not set) !");
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printf("\tThe cipher mode used in device context: '%s'\n", crypt_get_cipher_mode(cd) ?: "(not set) !");
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printf("\tThe device UUID '%s'\n", crypt_get_uuid(cd) ?: "(not set) !");
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EX_DELIM;
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/*
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* __STEP_06__
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*
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* Get info about active device (query DM backend)
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*/
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EX_PRESS_ENTER("Going to get active active device parameters.");
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EX_STEP(++step, "crypt_get_active_device()");
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if ((r = crypt_get_active_device(cd, EX_DEV_NAME, &cad))) {
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EX_FAIL("Get info about active device '%s' failed!", EX_DEV_NAME);
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goto out;
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}
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EX_SUCCESS("Active device parameters for " EX_DEV_NAME ":\n"
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"\tPayload offset (in sectors): %" PRIu64 "\n"
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"\tEncrypted payload area size in sectors: %" PRIu64 " and bytes: %" PRIu64 "\n"
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"\tThe device has a read-only flag %sset",
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cad.offset, cad.size, cad.size * SECTOR_SIZE,
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cad.flags & CRYPT_ACTIVATE_READONLY ? "" : "not ");
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EX_DELIM;
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crypt_free(cd);
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cd = NULL;
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/*
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* __STEP_07__
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*
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* crypt_init_by_name() initializes device context and loads LUKS header from backing device
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*/
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EX_PRESS_ENTER("The context used in previous examples is going to be freed to demonstrate "
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"how to initialize a device context from the active device.");
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EX_STEP(++step, "crypt_init_by_name()");
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if ((r = crypt_init_by_name(&cd, EX_DEV_NAME))) {
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EX_FAIL("crypt_init_by_name() failed for the device name: " EX_DEV_NAME);
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goto out;
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}
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EX_SUCCESS("A new context has been initialized, LUKS header has been restored"
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"\n\tDevice UUID is '%s'", crypt_get_uuid(cd));
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/*
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* __STEP_08__
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*
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* crypt_deactivate() is used to remove the volume_key from kernel mem. space and to remove the
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* device nod associated with decrypted backing device.
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*
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*/
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EX_PRESS_ENTER("\n\tGoing to deactivate the crypt device. Note that the device "
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"won't be deactivated while it's opened with O_EXCL flag (e.g. mounted).");
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EX_STEP(++step, "crypt_deactivate()");
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//printf("\nPress <ENTER> to continue to device deactivation of the test device.\n"
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// "Note that mounted device won't be deactivated. First unmount the device!");
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//getc(stdin);
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while ((r = crypt_deactivate(cd, EX_DEV_NAME))) {
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EX_FAIL("crypt_deactivate() failed. Most propably the device is still busy!");
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EX_PRESS_ENTER("Going to retry device deactivation");
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}
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EX_SUCCESS("crypt_deactivate() successful. Device " DMDIR EX_DEV_NAME " is now deactivated");
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out:
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if (crypt_status(cd, EX_DEV_NAME) == CRYPT_ACTIVE)
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crypt_deactivate(cd, EX_DEV_NAME);
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if (answer)
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free(answer);
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/* always free context which is no longer used */
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if (cd)
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crypt_free(cd);
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return r;
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}
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