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authfile.c
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authfile.c
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/* $OpenBSD: authfile.c,v 1.142 2022/01/01 01:55:30 jsg Exp $ */
/*
* Copyright (c) 2000, 2013 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>
#include <sys/uio.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include "cipher.h"
#include "ssh.h"
#include "log.h"
#include "authfile.h"
#include "misc.h"
#include "atomicio.h"
#include "sshkey.h"
#include "sshbuf.h"
#include "ssherr.h"
#include "krl.h"
#define MAX_KEY_FILE_SIZE (1024 * 1024)
/* Save a key blob to a file */
static int
sshkey_save_private_blob(struct sshbuf *keybuf, const char *filename)
{
int r;
mode_t omask;
omask = umask(077);
r = sshbuf_write_file(filename, keybuf);
umask(omask);
return r;
}
int
sshkey_save_private(struct sshkey *key, const char *filename,
const char *passphrase, const char *comment,
int format, const char *openssh_format_cipher, int openssh_format_rounds)
{
struct sshbuf *keyblob = NULL;
int r;
if ((keyblob = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshkey_private_to_fileblob(key, keyblob, passphrase, comment,
format, openssh_format_cipher, openssh_format_rounds)) != 0)
goto out;
if ((r = sshkey_save_private_blob(keyblob, filename)) != 0)
goto out;
r = 0;
out:
sshbuf_free(keyblob);
return r;
}
/* XXX remove error() calls from here? */
int
sshkey_perm_ok(int fd, const char *filename)
{
struct stat st;
if (fstat(fd, &st) == -1)
return SSH_ERR_SYSTEM_ERROR;
/*
* if a key owned by the user is accessed, then we check the
* permissions of the file. if the key owned by a different user,
* then we don't care.
*/
#ifdef HAVE_CYGWIN
if (check_ntsec(filename))
#endif
if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) {
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("Permissions 0%3.3o for '%s' are too open.",
(u_int)st.st_mode & 0777, filename);
error("It is required that your private key files are NOT accessible by others.");
error("This private key will be ignored.");
return SSH_ERR_KEY_BAD_PERMISSIONS;
}
return 0;
}
int
sshkey_load_private_type(int type, const char *filename, const char *passphrase,
struct sshkey **keyp, char **commentp)
{
int fd, r;
if (keyp != NULL)
*keyp = NULL;
if (commentp != NULL)
*commentp = NULL;
if ((fd = open(filename, O_RDONLY)) == -1)
return SSH_ERR_SYSTEM_ERROR;
r = sshkey_perm_ok(fd, filename);
if (r != 0)
goto out;
r = sshkey_load_private_type_fd(fd, type, passphrase, keyp, commentp);
if (r == 0 && keyp && *keyp)
r = sshkey_set_filename(*keyp, filename);
out:
close(fd);
return r;
}
int
sshkey_load_private(const char *filename, const char *passphrase,
struct sshkey **keyp, char **commentp)
{
return sshkey_load_private_type(KEY_UNSPEC, filename, passphrase,
keyp, commentp);
}
int
sshkey_load_private_type_fd(int fd, int type, const char *passphrase,
struct sshkey **keyp, char **commentp)
{
struct sshbuf *buffer = NULL;
int r;
if (keyp != NULL)
*keyp = NULL;
if ((r = sshbuf_load_fd(fd, &buffer)) != 0 ||
(r = sshkey_parse_private_fileblob_type(buffer, type,
passphrase, keyp, commentp)) != 0)
goto out;
/* success */
r = 0;
out:
sshbuf_free(buffer);
return r;
}
/* Load a pubkey from the unencrypted envelope of a new-format private key */
static int
sshkey_load_pubkey_from_private(const char *filename, struct sshkey **pubkeyp)
{
struct sshbuf *buffer = NULL;
struct sshkey *pubkey = NULL;
int r, fd;
if (pubkeyp != NULL)
*pubkeyp = NULL;
if ((fd = open(filename, O_RDONLY)) == -1)
return SSH_ERR_SYSTEM_ERROR;
if ((r = sshbuf_load_fd(fd, &buffer)) != 0 ||
(r = sshkey_parse_pubkey_from_private_fileblob_type(buffer,
KEY_UNSPEC, &pubkey)) != 0)
goto out;
if ((r = sshkey_set_filename(pubkey, filename)) != 0)
goto out;
/* success */
if (pubkeyp != NULL) {
*pubkeyp = pubkey;
pubkey = NULL;
}
r = 0;
out:
close(fd);
sshbuf_free(buffer);
sshkey_free(pubkey);
return r;
}
static int
sshkey_try_load_public(struct sshkey **kp, const char *filename,
char **commentp)
{
FILE *f;
char *line = NULL, *cp;
size_t linesize = 0;
int r;
struct sshkey *k = NULL;
*kp = NULL;
if (commentp != NULL)
*commentp = NULL;
if ((f = fopen(filename, "r")) == NULL)
return SSH_ERR_SYSTEM_ERROR;
if ((k = sshkey_new(KEY_UNSPEC)) == NULL) {
fclose(f);
return SSH_ERR_ALLOC_FAIL;
}
while (getline(&line, &linesize, f) != -1) {
cp = line;
switch (*cp) {
case '#':
case '\n':
case '\0':
continue;
}
/* Abort loading if this looks like a private key */
if (strncmp(cp, "-----BEGIN", 10) == 0 ||
strcmp(cp, "SSH PRIVATE KEY FILE") == 0)
break;
/* Skip leading whitespace. */
for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
;
if (*cp) {
if ((r = sshkey_read(k, &cp)) == 0) {
cp[strcspn(cp, "\r\n")] = '\0';
if (commentp) {
*commentp = strdup(*cp ?
cp : filename);
if (*commentp == NULL)
r = SSH_ERR_ALLOC_FAIL;
}
/* success */
*kp = k;
free(line);
fclose(f);
return r;
}
}
}
free(k);
free(line);
fclose(f);
return SSH_ERR_INVALID_FORMAT;
}
/* load public key from any pubkey file */
int
sshkey_load_public(const char *filename, struct sshkey **keyp, char **commentp)
{
char *pubfile = NULL;
int r, oerrno;
if (keyp != NULL)
*keyp = NULL;
if (commentp != NULL)
*commentp = NULL;
if ((r = sshkey_try_load_public(keyp, filename, commentp)) == 0)
goto out;
/* try .pub suffix */
if (asprintf(&pubfile, "%s.pub", filename) == -1)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshkey_try_load_public(keyp, pubfile, commentp)) == 0)
goto out;
/* finally, try to extract public key from private key file */
if ((r = sshkey_load_pubkey_from_private(filename, keyp)) == 0)
goto out;
/* Pretend we couldn't find the key */
r = SSH_ERR_SYSTEM_ERROR;
errno = ENOENT;
out:
oerrno = errno;
free(pubfile);
errno = oerrno;
return r;
}
/* Load the certificate associated with the named private key */
int
sshkey_load_cert(const char *filename, struct sshkey **keyp)
{
struct sshkey *pub = NULL;
char *file = NULL;
int r = SSH_ERR_INTERNAL_ERROR;
if (keyp != NULL)
*keyp = NULL;
if (asprintf(&file, "%s-cert.pub", filename) == -1)
return SSH_ERR_ALLOC_FAIL;
r = sshkey_try_load_public(keyp, file, NULL);
free(file);
sshkey_free(pub);
return r;
}
/* Load private key and certificate */
int
sshkey_load_private_cert(int type, const char *filename, const char *passphrase,
struct sshkey **keyp)
{
struct sshkey *key = NULL, *cert = NULL;
int r;
if (keyp != NULL)
*keyp = NULL;
switch (type) {
#ifdef WITH_OPENSSL
case KEY_RSA:
case KEY_DSA:
case KEY_ECDSA:
#endif /* WITH_OPENSSL */
case KEY_ED25519:
case KEY_XMSS:
case KEY_UNSPEC:
break;
default:
return SSH_ERR_KEY_TYPE_UNKNOWN;
}
if ((r = sshkey_load_private_type(type, filename,
passphrase, &key, NULL)) != 0 ||
(r = sshkey_load_cert(filename, &cert)) != 0)
goto out;
/* Make sure the private key matches the certificate */
if (sshkey_equal_public(key, cert) == 0) {
r = SSH_ERR_KEY_CERT_MISMATCH;
goto out;
}
if ((r = sshkey_to_certified(key)) != 0 ||
(r = sshkey_cert_copy(cert, key)) != 0)
goto out;
r = 0;
if (keyp != NULL) {
*keyp = key;
key = NULL;
}
out:
sshkey_free(key);
sshkey_free(cert);
return r;
}
/*
* Returns success if the specified "key" is listed in the file "filename",
* SSH_ERR_KEY_NOT_FOUND: if the key is not listed or another error.
* If "strict_type" is set then the key type must match exactly,
* otherwise a comparison that ignores certificate data is performed.
* If "check_ca" is set and "key" is a certificate, then its CA key is
* also checked and sshkey_in_file() will return success if either is found.
*/
int
sshkey_in_file(struct sshkey *key, const char *filename, int strict_type,
int check_ca)
{
FILE *f;
char *line = NULL, *cp;
size_t linesize = 0;
int r = 0;
struct sshkey *pub = NULL;
int (*sshkey_compare)(const struct sshkey *, const struct sshkey *) =
strict_type ? sshkey_equal : sshkey_equal_public;
if ((f = fopen(filename, "r")) == NULL)
return SSH_ERR_SYSTEM_ERROR;
while (getline(&line, &linesize, f) != -1) {
sshkey_free(pub);
pub = NULL;
cp = line;
/* Skip leading whitespace. */
for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
;
/* Skip comments and empty lines */
switch (*cp) {
case '#':
case '\n':
case '\0':
continue;
}
if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
switch (r = sshkey_read(pub, &cp)) {
case 0:
break;
case SSH_ERR_KEY_LENGTH:
continue;
default:
goto out;
}
if (sshkey_compare(key, pub) ||
(check_ca && sshkey_is_cert(key) &&
sshkey_compare(key->cert->signature_key, pub))) {
r = 0;
goto out;
}
}
r = SSH_ERR_KEY_NOT_FOUND;
out:
free(line);
sshkey_free(pub);
fclose(f);
return r;
}
/*
* Checks whether the specified key is revoked, returning 0 if not,
* SSH_ERR_KEY_REVOKED if it is or another error code if something
* unexpected happened.
* This will check both the key and, if it is a certificate, its CA key too.
* "revoked_keys_file" may be a KRL or a one-per-line list of public keys.
*/
int
sshkey_check_revoked(struct sshkey *key, const char *revoked_keys_file)
{
int r;
r = ssh_krl_file_contains_key(revoked_keys_file, key);
/* If this was not a KRL to begin with then continue below */
if (r != SSH_ERR_KRL_BAD_MAGIC)
return r;
/*
* If the file is not a KRL or we can't handle KRLs then attempt to
* parse the file as a flat list of keys.
*/
switch ((r = sshkey_in_file(key, revoked_keys_file, 0, 1))) {
case 0:
/* Key found => revoked */
return SSH_ERR_KEY_REVOKED;
case SSH_ERR_KEY_NOT_FOUND:
/* Key not found => not revoked */
return 0;
default:
/* Some other error occurred */
return r;
}
}
/*
* Advanced *cpp past the end of key options, defined as the first unquoted
* whitespace character. Returns 0 on success or -1 on failure (e.g.
* unterminated quotes).
*/
int
sshkey_advance_past_options(char **cpp)
{
char *cp = *cpp;
int quoted = 0;
for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
if (*cp == '\\' && cp[1] == '"')
cp++; /* Skip both */
else if (*cp == '"')
quoted = !quoted;
}
*cpp = cp;
/* return failure for unterminated quotes */
return (*cp == '\0' && quoted) ? -1 : 0;
}
/* Save a public key */
int
sshkey_save_public(const struct sshkey *key, const char *path,
const char *comment)
{
int fd, oerrno;
FILE *f = NULL;
int r = SSH_ERR_INTERNAL_ERROR;
if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1)
return SSH_ERR_SYSTEM_ERROR;
if ((f = fdopen(fd, "w")) == NULL) {
r = SSH_ERR_SYSTEM_ERROR;
goto fail;
}
if ((r = sshkey_write(key, f)) != 0)
goto fail;
fprintf(f, " %s\n", comment);
if (ferror(f) || fclose(f) != 0) {
r = SSH_ERR_SYSTEM_ERROR;
fail:
oerrno = errno;
if (f != NULL)
fclose(f);
else
close(fd);
errno = oerrno;
return r;
}
return 0;
}