libssh/examples/keygen2.c
Jakub Jelen 14ff31490f examples: Update keygen2 example to show fingerprints
Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit f193e6840d)
2022-08-03 10:49:22 +02:00

506 lines
14 KiB
C

/*
* keygen2.c - Generate SSH keys using libssh
* Author: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
*/
/*
* Copyright (c) 2019 Red Hat, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see http://www.gnu.org/licenses/.
*/
#include "config.h"
#include <libssh/libssh.h>
#include <stdio.h>
#include <stdlib.h>
#include <argp.h>
#include <errno.h>
#include <string.h>
#include <ctype.h>
#include <fcntl.h>
#include <sys/stat.h>
struct arguments_st {
enum ssh_keytypes_e type;
unsigned long bits;
char *file;
char *passphrase;
int action_list;
};
static struct argp_option options[] = {
{
.name = "bits",
.key = 'b',
.arg = "BITS",
.flags = 0,
.doc = "The size of the key to be generated. "
"If omitted, a default value is used depending on the TYPE. "
"Accepted values are: "
"1024, 2048, 3072 (default), 4096, and 8192 for TYPE=\"rsa\"; "
"256 (default), 384, and 521 for TYPE=\"ecdsa\"; "
"1024 (default) and 2048 for TYPE=\"dsa\"; "
"can be omitted for TYPE=\"ed25519\" "
"(it will be ignored if provided).\n",
.group = 0
},
{
.name = "file",
.key = 'f',
.arg = "FILE",
.flags = 0,
.doc = "The output file. "
"If not provided, the used file name will be generated "
"according to the key type as \"id_TYPE\" "
"(e.g. \"id_rsa\" for type \"rsa\"). "
"The public key file name is generated from the private key "
"file name by appending \".pub\".\n",
.group = 0
},
{
.name = "passphrase",
.key = 'p',
.arg = "PASSPHRASE",
.flags = 0,
.doc = "The passphrase used to encrypt the private key. "
"If omitted the file will not be encrypted.\n",
.group = 0
},
{
.name = "type",
.key = 't',
.arg = "TYPE",
.flags = 0,
.doc = "The type of the key to be generated. "
"Accepted values are: "
"\"rsa\", \"ecdsa\", \"ed25519\", and \"dsa\".\n",
.group = 0
},
{
.name = "list",
.key = 'l',
.arg = NULL,
.flags = 0,
.doc = "List the Fingerprint of the given key\n",
.group = 0
},
{
/* End of the options */
0
},
};
/* Parse a single option. */
static error_t parse_opt (int key, char *arg, struct argp_state *state)
{
/* Get the input argument from argp_parse, which we
* know is a pointer to our arguments structure.
*/
struct arguments_st *arguments = NULL;
error_t rc = 0;
if (state == NULL) {
return EINVAL;
}
arguments = state->input;
if (arguments == NULL) {
fprintf(stderr, "Error: NULL pointer to arguments structure "
"provided\n");
rc = EINVAL;
goto end;
}
switch (key) {
case 'b':
errno = 0;
arguments->bits = strtoul(arg, NULL, 10);
if (errno != 0) {
rc = errno;
goto end;
}
break;
case 'f':
arguments->file = strdup(arg);
if (arguments->file == NULL) {
fprintf(stderr, "Error: Out of memory\n");
rc = ENOMEM;
goto end;
}
break;
case 'p':
arguments->passphrase = strdup(arg);
if (arguments->passphrase == NULL) {
fprintf(stderr, "Error: Out of memory\n");
rc = ENOMEM;
goto end;
}
break;
case 't':
if (!strcmp(arg, "rsa")) {
arguments->type = SSH_KEYTYPE_RSA;
}
else if (!strcmp(arg, "dsa")) {
arguments->type = SSH_KEYTYPE_DSS;
}
else if (!strcmp(arg, "ecdsa")) {
arguments->type = SSH_KEYTYPE_ECDSA;
}
else if (!strcmp(arg, "ed25519")) {
arguments->type = SSH_KEYTYPE_ED25519;
}
else {
fprintf(stderr, "Error: Invalid key type\n");
argp_usage(state);
rc = EINVAL;
goto end;
}
break;
case 'l':
arguments->action_list = 1;
break;
case ARGP_KEY_ARG:
if (state->arg_num > 0) {
/* Too many arguments. */
printf("Error: Too many arguments\n");
argp_usage(state);
}
break;
case ARGP_KEY_END:
break;
default:
return ARGP_ERR_UNKNOWN;
}
end:
return rc;
}
static int validate_args(struct arguments_st *args)
{
int rc = 0;
if (args == NULL) {
return EINVAL;
}
/* no other arguments needed for listing key fingerprints */
if (args->action_list) {
return 0;
}
switch (args->type) {
case SSH_KEYTYPE_RSA:
switch (args->bits) {
case 0:
/* If not provided, use default value */
args->bits = 3072;
break;
case 1024:
case 2048:
case 3072:
case 4096:
case 8192:
break;
default:
fprintf(stderr, "Error: Invalid bits parameter provided\n");
rc = EINVAL;
break;
}
if (args->file == NULL) {
args->file = strdup("id_rsa");
if (args->file == NULL) {
rc = ENOMEM;
break;
}
}
break;
case SSH_KEYTYPE_ECDSA:
switch (args->bits) {
case 0:
/* If not provided, use default value */
args->bits = 256;
break;
case 256:
case 384:
case 521:
break;
default:
fprintf(stderr, "Error: Invalid bits parameter provided\n");
rc = EINVAL;
break;
}
if (args->file == NULL) {
args->file = strdup("id_ecdsa");
if (args->file == NULL) {
rc = ENOMEM;
break;
}
}
break;
case SSH_KEYTYPE_DSS:
switch (args->bits) {
case 0:
/* If not provided, use default value */
args->bits = 1024;
break;
case 1024:
case 2048:
break;
default:
fprintf(stderr, "Error: Invalid bits parameter provided\n");
rc = EINVAL;
break;
}
if (args->file == NULL) {
args->file = strdup("id_dsa");
if (args->file == NULL) {
rc = ENOMEM;
break;
}
}
break;
case SSH_KEYTYPE_ED25519:
/* Ignore value and overwrite with a zero */
args->bits = 0;
if (args->file == NULL) {
args->file = strdup("id_ed25519");
if (args->file == NULL) {
rc = ENOMEM;
break;
}
}
break;
default:
fprintf(stderr, "Error: unknown key type\n");
rc = EINVAL;
break;
}
return rc;
}
/* Program documentation. */
static char doc[] = "Generate an SSH key pair. "
"The \"--type\" (short: \"-t\") option is required.";
/* Our argp parser */
static struct argp argp = {options, parse_opt, NULL, doc, NULL, NULL, NULL};
static void
list_fingerprint(char *file)
{
ssh_key key = NULL;
unsigned char *hash = NULL;
size_t hlen = 0;
int rc;
rc = ssh_pki_import_privkey_file(file, NULL, NULL, NULL, &key);
if (rc != SSH_OK) {
fprintf(stderr, "Failed to import private key %s\n", file);
return;
}
rc = ssh_get_publickey_hash(key, SSH_PUBLICKEY_HASH_SHA256, &hash, &hlen);
if (rc != SSH_OK) {
fprintf(stderr, "Failed to get key fingerprint\n");
return;
}
ssh_print_hash(SSH_PUBLICKEY_HASH_SHA256, hash, hlen);
ssh_clean_pubkey_hash(&hash);
ssh_key_free(key);
}
int main(int argc, char *argv[])
{
ssh_key key = NULL;
int rc = 0;
char overwrite[1024] = "";
char *pubkey_file = NULL;
struct arguments_st arguments = {
.type = SSH_KEYTYPE_UNKNOWN,
.bits = 0,
.file = NULL,
.passphrase = NULL,
.action_list = 0,
};
if (argc < 2) {
argp_help(&argp, stdout, ARGP_HELP_DOC | ARGP_HELP_USAGE, argv[0]);
goto end;
}
rc = argp_parse(&argp, argc, argv, 0, 0, &arguments);
if (rc != 0) {
goto end;
}
rc = validate_args(&arguments);
if (rc != 0) {
goto end;
}
if (arguments.action_list && arguments.file) {
list_fingerprint(arguments.file);
goto end;
}
errno = 0;
rc = open(arguments.file, O_CREAT | O_EXCL | O_WRONLY, S_IRUSR | S_IWUSR);
if (rc < 0) {
if (errno == EEXIST) {
printf("File \"%s\" exists. Overwrite it? (y|n) ", arguments.file);
rc = scanf("%1023s", overwrite);
if (rc > 0 && tolower(overwrite[0]) == 'y') {
rc = open(arguments.file, O_WRONLY);
if (rc > 0) {
close(rc);
errno = 0;
rc = chmod(arguments.file, S_IRUSR | S_IWUSR);
if (rc != 0) {
fprintf(stderr,
"Error(%d): Could not set file permissions\n",
errno);
goto end;
}
} else {
fprintf(stderr,
"Error: Could not create private key file\n");
goto end;
}
} else {
goto end;
}
} else {
fprintf(stderr, "Error opening \"%s\" file\n", arguments.file);
goto end;
}
} else {
close(rc);
}
/* Generate a new private key */
rc = ssh_pki_generate(arguments.type, arguments.bits, &key);
if (rc != SSH_OK) {
fprintf(stderr, "Error: Failed to generate keys");
goto end;
}
/* Write the private key */
rc = ssh_pki_export_privkey_file(key, arguments.passphrase, NULL, NULL,
arguments.file);
if (rc != SSH_OK) {
fprintf(stderr, "Error: Failed to write private key file");
goto end;
}
/* If a passphrase was provided, overwrite and free it as it is not needed
* anymore */
if (arguments.passphrase != NULL) {
#ifdef HAVE_EXPLICIT_BZERO
explicit_bzero(arguments.passphrase, strlen(arguments.passphrase));
#else
bzero(arguments.passphrase, strlen(arguments.passphrase));
#endif
free(arguments.passphrase);
arguments.passphrase = NULL;
}
pubkey_file = (char *)malloc(strlen(arguments.file) + 5);
if (pubkey_file == NULL) {
rc = ENOMEM;
goto end;
}
sprintf(pubkey_file, "%s.pub", arguments.file);
errno = 0;
rc = open(pubkey_file,
O_CREAT | O_EXCL | O_WRONLY,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (rc < 0) {
if (errno == EEXIST) {
printf("File \"%s\" exists. Overwrite it? (y|n) ", pubkey_file);
rc = scanf("%1023s", overwrite);
if (rc > 0 && tolower(overwrite[0]) == 'y') {
rc = open(pubkey_file, O_WRONLY);
if (rc > 0) {
close(rc);
errno = 0;
rc = chmod(pubkey_file,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (rc != 0) {
fprintf(stderr,
"Error(%d): Could not set file permissions\n",
errno);
goto end;
}
} else {
fprintf(stderr,
"Error: Could not create public key file\n");
goto end;
}
} else {
goto end;
}
} else {
fprintf(stderr, "Error opening \"%s\" file\n", pubkey_file);
goto end;
}
} else {
close(rc);
}
/* Write the public key */
rc = ssh_pki_export_pubkey_file(key, pubkey_file);
if (rc != SSH_OK) {
fprintf(stderr, "Error: Failed to write public key file");
goto end;
}
end:
if (key != NULL) {
ssh_key_free(key);
}
if (arguments.file != NULL) {
free(arguments.file);
}
if (arguments.passphrase != NULL) {
#ifdef HAVE_EXPLICIT_BZERO
explicit_bzero(arguments.passphrase, strlen(arguments.passphrase));
#else
bzero(arguments.passphrase, strlen(arguments.passphrase));
#endif
free(arguments.passphrase);
}
if (pubkey_file != NULL) {
free(pubkey_file);
}
return rc;
}