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/* $OpenBSD: ssh-add.c,v 1.144 2019/11/12 19:33:08 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Adds an identity to the authentication server, or removes an identity.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
* SSH2 implementation,
* Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/stat.h>
#ifdef WITH_OPENSSL
# include <openssl/evp.h>
# include "openbsd-compat/openssl-compat.h"
#endif
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include "xmalloc.h"
#include "ssh.h"
#include "log.h"
#include "sshkey.h"
#include "sshbuf.h"
#include "authfd.h"
#include "authfile.h"
#include "pathnames.h"
#include "misc.h"
#include "ssherr.h"
#include "digest.h"
/* argv0 */
extern char *__progname;
/* Default files to add */
static char *default_files[] = {
#ifdef WITH_OPENSSL
_PATH_SSH_CLIENT_ID_RSA,
_PATH_SSH_CLIENT_ID_DSA,
#ifdef OPENSSL_HAS_ECC
_PATH_SSH_CLIENT_ID_ECDSA,
_PATH_SSH_CLIENT_ID_ECDSA_SK,
#endif
#endif /* WITH_OPENSSL */
_PATH_SSH_CLIENT_ID_ED25519,
_PATH_SSH_CLIENT_ID_ED25519_SK,
_PATH_SSH_CLIENT_ID_XMSS,
NULL
};
static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
/* Default lifetime (0 == forever) */
static int lifetime = 0;
/* User has to confirm key use */
static int confirm = 0;
/* Maximum number of signatures (XMSS) */
static u_int maxsign = 0;
static u_int minleft = 0;
/* we keep a cache of one passphrase */
static char *pass = NULL;
static void
clear_pass(void)
{
if (pass) {
explicit_bzero(pass, strlen(pass));
free(pass);
pass = NULL;
}
}
static int
delete_file(int agent_fd, const char *filename, int key_only, int qflag)
{
struct sshkey *public, *cert = NULL;
char *certpath = NULL, *comment = NULL;
int r, ret = -1;
if ((r = sshkey_load_public(filename, &public, &comment)) != 0) {
printf("Bad key file %s: %s\n", filename, ssh_err(r));
return -1;
}
if ((r = ssh_remove_identity(agent_fd, public)) == 0) {
if (!qflag) {
fprintf(stderr, "Identity removed: %s (%s)\n",
filename, comment);
}
ret = 0;
} else
fprintf(stderr, "Could not remove identity \"%s\": %s\n",
filename, ssh_err(r));
if (key_only)
goto out;
/* Now try to delete the corresponding certificate too */
free(comment);
comment = NULL;
xasprintf(&certpath, "%s-cert.pub", filename);
if ((r = sshkey_load_public(certpath, &cert, &comment)) != 0) {
if (r != SSH_ERR_SYSTEM_ERROR || errno != ENOENT)
error("Failed to load certificate \"%s\": %s",
certpath, ssh_err(r));
goto out;
}
if (!sshkey_equal_public(cert, public))
fatal("Certificate %s does not match private key %s",
certpath, filename);
if ((r = ssh_remove_identity(agent_fd, cert)) == 0) {
if (!qflag) {
fprintf(stderr, "Identity removed: %s (%s)\n",
certpath, comment);
}
ret = 0;
} else
fprintf(stderr, "Could not remove identity \"%s\": %s\n",
certpath, ssh_err(r));
out:
sshkey_free(cert);
sshkey_free(public);
free(certpath);
free(comment);
return ret;
}
/* Send a request to remove all identities. */
static int
delete_all(int agent_fd, int qflag)
{
int ret = -1;
/*
* Since the agent might be forwarded, old or non-OpenSSH, when asked
* to remove all keys, attempt to remove both protocol v.1 and v.2
* keys.
*/
if (ssh_remove_all_identities(agent_fd, 2) == 0)
ret = 0;
/* ignore error-code for ssh1 */
ssh_remove_all_identities(agent_fd, 1);
if (ret != 0)
fprintf(stderr, "Failed to remove all identities.\n");
else if (!qflag)
fprintf(stderr, "All identities removed.\n");
return ret;
}
static int
add_file(int agent_fd, const char *filename, int key_only, int qflag,
const char *skprovider)
{
struct sshkey *private, *cert;
char *comment = NULL;
char msg[1024], *certpath = NULL;
int r, fd, ret = -1;
size_t i;
u_int32_t left;
struct sshbuf *keyblob;
struct ssh_identitylist *idlist;
if (strcmp(filename, "-") == 0) {
fd = STDIN_FILENO;
filename = "(stdin)";
} else if ((fd = open(filename, O_RDONLY)) == -1) {
perror(filename);
return -1;
}
/*
* Since we'll try to load a keyfile multiple times, permission errors
* will occur multiple times, so check perms first and bail if wrong.
*/
if (fd != STDIN_FILENO) {
if (sshkey_perm_ok(fd, filename) != 0) {
close(fd);
return -1;
}
}
if ((keyblob = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshkey_load_file(fd, keyblob)) != 0) {
fprintf(stderr, "Error loading key \"%s\": %s\n",
filename, ssh_err(r));
sshbuf_free(keyblob);
close(fd);
return -1;
}
close(fd);
/* At first, try empty passphrase */
if ((r = sshkey_parse_private_fileblob(keyblob, "", &private,
&comment)) != 0 && r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
fprintf(stderr, "Error loading key \"%s\": %s\n",
filename, ssh_err(r));
goto fail_load;
}
/* try last */
if (private == NULL && pass != NULL) {
if ((r = sshkey_parse_private_fileblob(keyblob, pass, &private,
&comment)) != 0 && r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
fprintf(stderr, "Error loading key \"%s\": %s\n",
filename, ssh_err(r));
goto fail_load;
}
}
if (private == NULL) {
/* clear passphrase since it did not work */
clear_pass();
snprintf(msg, sizeof msg, "Enter passphrase for %s%s: ",
filename, confirm ? " (will confirm each use)" : "");
for (;;) {
pass = read_passphrase(msg, RP_ALLOW_STDIN);
if (strcmp(pass, "") == 0)
goto fail_load;
if ((r = sshkey_parse_private_fileblob(keyblob, pass,
&private, &comment)) == 0)
break;
else if (r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
fprintf(stderr,
"Error loading key \"%s\": %s\n",
filename, ssh_err(r));
fail_load:
clear_pass();
sshbuf_free(keyblob);
return -1;
}
clear_pass();
snprintf(msg, sizeof msg,
"Bad passphrase, try again for %s%s: ", filename,
confirm ? " (will confirm each use)" : "");
}
}
if (comment == NULL || *comment == '\0')
comment = xstrdup(filename);
sshbuf_free(keyblob);
/* For XMSS */
if ((r = sshkey_set_filename(private, filename)) != 0) {
fprintf(stderr, "Could not add filename to private key: %s (%s)\n",
filename, comment);
goto out;
}
if (maxsign && minleft &&
(r = ssh_fetch_identitylist(agent_fd, &idlist)) == 0) {
for (i = 0; i < idlist->nkeys; i++) {
if (!sshkey_equal_public(idlist->keys[i], private))
continue;
left = sshkey_signatures_left(idlist->keys[i]);
if (left < minleft) {
fprintf(stderr,
"Only %d signatures left.\n", left);
break;
}
fprintf(stderr, "Skipping update: ");
if (left == minleft) {
fprintf(stderr,
"required signatures left (%d).\n", left);
} else {
fprintf(stderr,
"more signatures left (%d) than"
" required (%d).\n", left, minleft);
}
ssh_free_identitylist(idlist);
goto out;
}
ssh_free_identitylist(idlist);
}
if (!sshkey_is_sk(private))
skprovider = NULL; /* Don't send constraint for other keys */
else if (skprovider == NULL) {
fprintf(stderr, "Cannot load security key %s without "
"provider\n", filename);
goto out;
}
if ((r = ssh_add_identity_constrained(agent_fd, private, comment,
lifetime, confirm, maxsign, skprovider)) == 0) {
ret = 0;
if (!qflag) {
fprintf(stderr, "Identity added: %s (%s)\n",
filename, comment);
if (lifetime != 0) {
fprintf(stderr,
"Lifetime set to %d seconds\n", lifetime);
}
if (confirm != 0) {
fprintf(stderr, "The user must confirm "
"each use of the key\n");
}
}
} else {
fprintf(stderr, "Could not add identity \"%s\": %s\n",
filename, ssh_err(r));
}
/* Skip trying to load the cert if requested */
if (key_only)
goto out;
/* Now try to add the certificate flavour too */
xasprintf(&certpath, "%s-cert.pub", filename);
if ((r = sshkey_load_public(certpath, &cert, NULL)) != 0) {
if (r != SSH_ERR_SYSTEM_ERROR || errno != ENOENT)
error("Failed to load certificate \"%s\": %s",
certpath, ssh_err(r));
goto out;
}
if (!sshkey_equal_public(cert, private)) {
error("Certificate %s does not match private key %s",
certpath, filename);
sshkey_free(cert);
goto out;
}
/* Graft with private bits */
if ((r = sshkey_to_certified(private)) != 0) {
error("%s: sshkey_to_certified: %s", __func__, ssh_err(r));
sshkey_free(cert);
goto out;
}
if ((r = sshkey_cert_copy(cert, private)) != 0) {
error("%s: sshkey_cert_copy: %s", __func__, ssh_err(r));
sshkey_free(cert);
goto out;
}
sshkey_free(cert);
if ((r = ssh_add_identity_constrained(agent_fd, private, comment,
lifetime, confirm, maxsign, skprovider)) != 0) {
error("Certificate %s (%s) add failed: %s", certpath,
private->cert->key_id, ssh_err(r));
goto out;
}
/* success */
if (!qflag) {
fprintf(stderr, "Certificate added: %s (%s)\n", certpath,
private->cert->key_id);
if (lifetime != 0) {
fprintf(stderr, "Lifetime set to %d seconds\n",
lifetime);
}
if (confirm != 0) {
fprintf(stderr, "The user must confirm each use "
"of the key\n");
}
}
out:
free(certpath);
free(comment);
sshkey_free(private);
return ret;
}
static int
update_card(int agent_fd, int add, const char *id, int qflag)
{
char *pin = NULL;
int r, ret = -1;
if (add) {
if ((pin = read_passphrase("Enter passphrase for PKCS#11: ",
RP_ALLOW_STDIN)) == NULL)
return -1;
}
if ((r = ssh_update_card(agent_fd, add, id, pin == NULL ? "" : pin,
lifetime, confirm)) == 0) {
ret = 0;
if (!qflag) {
fprintf(stderr, "Card %s: %s\n",
add ? "added" : "removed", id);
}
} else {
fprintf(stderr, "Could not %s card \"%s\": %s\n",
add ? "add" : "remove", id, ssh_err(r));
ret = -1;
}
free(pin);
return ret;
}
static int
test_key(int agent_fd, const char *filename)
{
struct sshkey *key = NULL;
u_char *sig = NULL;
size_t slen = 0;
int r, ret = -1;
char data[1024];
if ((r = sshkey_load_public(filename, &key, NULL)) != 0) {
error("Couldn't read public key %s: %s", filename, ssh_err(r));
return -1;
}
arc4random_buf(data, sizeof(data));
if ((r = ssh_agent_sign(agent_fd, key, &sig, &slen, data, sizeof(data),
NULL, 0)) != 0) {
error("Agent signature failed for %s: %s",
filename, ssh_err(r));
goto done;
}
if ((r = sshkey_verify(key, sig, slen, data, sizeof(data),
NULL, 0)) != 0) {
error("Signature verification failed for %s: %s",
filename, ssh_err(r));
goto done;
}
/* success */
ret = 0;
done:
free(sig);
sshkey_free(key);
return ret;
}
static int
list_identities(int agent_fd, int do_fp)
{
char *fp;
int r;
struct ssh_identitylist *idlist;
u_int32_t left;
size_t i;
if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
if (r != SSH_ERR_AGENT_NO_IDENTITIES)
fprintf(stderr, "error fetching identities: %s\n",
ssh_err(r));
else
printf("The agent has no identities.\n");
return -1;
}
for (i = 0; i < idlist->nkeys; i++) {
if (do_fp) {
fp = sshkey_fingerprint(idlist->keys[i],
fingerprint_hash, SSH_FP_DEFAULT);
printf("%u %s %s (%s)\n", sshkey_size(idlist->keys[i]),
fp == NULL ? "(null)" : fp, idlist->comments[i],
sshkey_type(idlist->keys[i]));
free(fp);
} else {
if ((r = sshkey_write(idlist->keys[i], stdout)) != 0) {
fprintf(stderr, "sshkey_write: %s\n",
ssh_err(r));
continue;
}
fprintf(stdout, " %s", idlist->comments[i]);
left = sshkey_signatures_left(idlist->keys[i]);
if (left > 0)
fprintf(stdout,
" [signatures left %d]", left);
fprintf(stdout, "\n");
}
}
ssh_free_identitylist(idlist);
return 0;
}
static int
lock_agent(int agent_fd, int lock)
{
char prompt[100], *p1, *p2;
int r, passok = 1, ret = -1;
strlcpy(prompt, "Enter lock password: ", sizeof(prompt));
p1 = read_passphrase(prompt, RP_ALLOW_STDIN);
if (lock) {
strlcpy(prompt, "Again: ", sizeof prompt);
p2 = read_passphrase(prompt, RP_ALLOW_STDIN);
if (strcmp(p1, p2) != 0) {
fprintf(stderr, "Passwords do not match.\n");
passok = 0;
}
explicit_bzero(p2, strlen(p2));
free(p2);
}
if (passok) {
if ((r = ssh_lock_agent(agent_fd, lock, p1)) == 0) {
fprintf(stderr, "Agent %slocked.\n", lock ? "" : "un");
ret = 0;
} else {
fprintf(stderr, "Failed to %slock agent: %s\n",
lock ? "" : "un", ssh_err(r));
}
}
explicit_bzero(p1, strlen(p1));
free(p1);
return (ret);
}
static int
do_file(int agent_fd, int deleting, int key_only, char *file, int qflag,
const char *skprovider)
{
if (deleting) {
if (delete_file(agent_fd, file, key_only, qflag) == -1)
return -1;
} else {
if (add_file(agent_fd, file, key_only, qflag, skprovider) == -1)
return -1;
}
return 0;
}
static void
usage(void)
{
fprintf(stderr, "usage: %s [options] [file ...]\n", __progname);
fprintf(stderr, "Options:\n");
fprintf(stderr, " -l List fingerprints of all identities.\n");
fprintf(stderr, " -E hash Specify hash algorithm used for fingerprints.\n");
fprintf(stderr, " -L List public key parameters of all identities.\n");
fprintf(stderr, " -k Load only keys and not certificates.\n");
fprintf(stderr, " -c Require confirmation to sign using identities\n");
fprintf(stderr, " -m minleft Maxsign is only changed if less than minleft are left (for XMSS)\n");
fprintf(stderr, " -M maxsign Maximum number of signatures allowed (for XMSS)\n");
fprintf(stderr, " -t life Set lifetime (in seconds) when adding identities.\n");
fprintf(stderr, " -d Delete identity.\n");
fprintf(stderr, " -D Delete all identities.\n");
fprintf(stderr, " -x Lock agent.\n");
fprintf(stderr, " -X Unlock agent.\n");
fprintf(stderr, " -s pkcs11 Add keys from PKCS#11 provider.\n");
fprintf(stderr, " -e pkcs11 Remove keys provided by PKCS#11 provider.\n");
fprintf(stderr, " -T pubkey Test if ssh-agent can access matching private key.\n");
fprintf(stderr, " -S provider Specify security key provider.\n");
fprintf(stderr, " -q Be quiet after a successful operation.\n");
fprintf(stderr, " -v Be more verbose.\n");
}
int
main(int argc, char **argv)
{
extern char *optarg;
extern int optind;
int agent_fd;
char *pkcs11provider = NULL, *skprovider = NULL;
int r, i, ch, deleting = 0, ret = 0, key_only = 0;
int xflag = 0, lflag = 0, Dflag = 0, qflag = 0, Tflag = 0;
SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
LogLevel log_level = SYSLOG_LEVEL_INFO;
/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
sanitise_stdfd();
__progname = ssh_get_progname(argv[0]);
seed_rng();
log_init(__progname, log_level, log_facility, 1);
setvbuf(stdout, NULL, _IOLBF, 0);
/* First, get a connection to the authentication agent. */
switch (r = ssh_get_authentication_socket(&agent_fd)) {
case 0:
break;
case SSH_ERR_AGENT_NOT_PRESENT:
fprintf(stderr, "Could not open a connection to your "
"authentication agent.\n");
exit(2);
default:
fprintf(stderr, "Error connecting to agent: %s\n", ssh_err(r));
exit(2);
}
skprovider = getenv("SSH_SK_PROVIDER");
while ((ch = getopt(argc, argv, "vklLcdDTxXE:e:M:m:qs:S:t:")) != -1) {
switch (ch) {
case 'v':
if (log_level == SYSLOG_LEVEL_INFO)
log_level = SYSLOG_LEVEL_DEBUG1;
else if (log_level < SYSLOG_LEVEL_DEBUG3)
log_level++;
break;
case 'E':
fingerprint_hash = ssh_digest_alg_by_name(optarg);
if (fingerprint_hash == -1)
fatal("Invalid hash algorithm \"%s\"", optarg);
break;
case 'k':
key_only = 1;
break;
case 'l':
case 'L':
if (lflag != 0)
fatal("-%c flag already specified", lflag);
lflag = ch;
break;
case 'x':
case 'X':
if (xflag != 0)
fatal("-%c flag already specified", xflag);
xflag = ch;
break;
case 'c':
confirm = 1;
break;
case 'm':
minleft = (int)strtonum(optarg, 1, UINT_MAX, NULL);
if (minleft == 0) {
usage();
ret = 1;
goto done;
}
break;
case 'M':
maxsign = (int)strtonum(optarg, 1, UINT_MAX, NULL);
if (maxsign == 0) {
usage();
ret = 1;
goto done;
}
break;
case 'd':
deleting = 1;
break;
case 'D':
Dflag = 1;
break;
case 's':
pkcs11provider = optarg;
break;
case 'S':
skprovider = optarg;
break;
case 'e':
deleting = 1;
pkcs11provider = optarg;
break;
case 't':
if ((lifetime = convtime(optarg)) == -1) {
fprintf(stderr, "Invalid lifetime\n");
ret = 1;
goto done;
}
break;
case 'q':
qflag = 1;
break;
case 'T':
Tflag = 1;
break;
default:
usage();
ret = 1;
goto done;
}
}
log_init(__progname, log_level, log_facility, 1);
if ((xflag != 0) + (lflag != 0) + (Dflag != 0) > 1)
fatal("Invalid combination of actions");
else if (xflag) {
if (lock_agent(agent_fd, xflag == 'x' ? 1 : 0) == -1)
ret = 1;
goto done;
} else if (lflag) {
if (list_identities(agent_fd, lflag == 'l' ? 1 : 0) == -1)
ret = 1;
goto done;
} else if (Dflag) {
if (delete_all(agent_fd, qflag) == -1)
ret = 1;
goto done;
}
argc -= optind;
argv += optind;
if (Tflag) {
if (argc <= 0)
fatal("no keys to test");
for (r = i = 0; i < argc; i++)
r |= test_key(agent_fd, argv[i]);
ret = r == 0 ? 0 : 1;
goto done;
}
if (pkcs11provider != NULL) {
if (update_card(agent_fd, !deleting, pkcs11provider,
qflag) == -1)
ret = 1;
goto done;
}
if (argc == 0) {
char buf[PATH_MAX];
struct passwd *pw;
struct stat st;
int count = 0;
if ((pw = getpwuid(getuid())) == NULL) {
fprintf(stderr, "No user found with uid %u\n",
(u_int)getuid());
ret = 1;
goto done;
}
for (i = 0; default_files[i]; i++) {
snprintf(buf, sizeof(buf), "%s/%s", pw->pw_dir,
default_files[i]);
if (stat(buf, &st) == -1)
continue;
if (do_file(agent_fd, deleting, key_only, buf,
qflag, skprovider) == -1)
ret = 1;
else
count++;
}
if (count == 0)
ret = 1;
} else {
for (i = 0; i < argc; i++) {
if (do_file(agent_fd, deleting, key_only,
argv[i], qflag, skprovider) == -1)
ret = 1;
}
}
clear_pass();
done:
ssh_close_authentication_socket(agent_fd);
return ret;
}
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