openssh/ssh-add.c
djm@openbsd.org b7e74ea072 upstream: Add new structure for signature options
This is populated during signature verification with additional fields
that are present in and covered by the signature. At the moment, it is
only used to record security key-specific options, especially the flags
field.

with and ok markus@

OpenBSD-Commit-ID: 338a1f0e04904008836130bedb9ece4faafd4e49
2019-11-25 12:23:33 +11:00

778 lines
20 KiB
C

/* $OpenBSD: ssh-add.c,v 1.147 2019/11/25 00:51:37 djm 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, NULL)) != 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;
}
#ifdef ENABLE_SK_INTERNAL
if (skprovider == NULL)
skprovider = "internal";
#endif
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;
}