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-rw-r--r--authfile.c538
1 files changed, 538 insertions, 0 deletions
diff --git a/authfile.c b/authfile.c
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+/* $OpenBSD: authfile.c,v 1.131 2018/09/21 12:20:12 djm 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 fd, oerrno;
+
+ if ((fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600)) < 0)
+ return SSH_ERR_SYSTEM_ERROR;
+ if (atomicio(vwrite, fd, sshbuf_mutable_ptr(keybuf),
+ sshbuf_len(keybuf)) != sshbuf_len(keybuf)) {
+ oerrno = errno;
+ close(fd);
+ unlink(filename);
+ errno = oerrno;
+ return SSH_ERR_SYSTEM_ERROR;
+ }
+ close(fd);
+ return 0;
+}
+
+int
+sshkey_save_private(struct sshkey *key, const char *filename,
+ const char *passphrase, const char *comment,
+ int force_new_format, const char *new_format_cipher, int new_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,
+ force_new_format, new_format_cipher, new_format_rounds)) != 0)
+ goto out;
+ if ((r = sshkey_save_private_blob(keyblob, filename)) != 0)
+ goto out;
+ r = 0;
+ out:
+ sshbuf_free(keyblob);
+ return r;
+}
+
+/* Load a key from a fd into a buffer */
+int
+sshkey_load_file(int fd, struct sshbuf *blob)
+{
+ u_char buf[1024];
+ size_t len;
+ struct stat st;
+ int r;
+
+ if (fstat(fd, &st) < 0)
+ return SSH_ERR_SYSTEM_ERROR;
+ if ((st.st_mode & (S_IFSOCK|S_IFCHR|S_IFIFO)) == 0 &&
+ st.st_size > MAX_KEY_FILE_SIZE)
+ return SSH_ERR_INVALID_FORMAT;
+ for (;;) {
+ if ((len = atomicio(read, fd, buf, sizeof(buf))) == 0) {
+ if (errno == EPIPE)
+ break;
+ r = SSH_ERR_SYSTEM_ERROR;
+ goto out;
+ }
+ if ((r = sshbuf_put(blob, buf, len)) != 0)
+ goto out;
+ if (sshbuf_len(blob) > MAX_KEY_FILE_SIZE) {
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ }
+ if ((st.st_mode & (S_IFSOCK|S_IFCHR|S_IFIFO)) == 0 &&
+ st.st_size != (off_t)sshbuf_len(blob)) {
+ r = SSH_ERR_FILE_CHANGED;
+ goto out;
+ }
+ r = 0;
+
+ out:
+ explicit_bzero(buf, sizeof(buf));
+ if (r != 0)
+ sshbuf_reset(blob);
+ return r;
+}
+
+
+/* XXX remove error() calls from here? */
+int
+sshkey_perm_ok(int fd, const char *filename)
+{
+ struct stat st;
+
+ if (fstat(fd, &st) < 0)
+ 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;
+}
+
+/* XXX kill perm_ok now that we have SSH_ERR_KEY_BAD_PERMISSIONS? */
+int
+sshkey_load_private_type(int type, const char *filename, const char *passphrase,
+ struct sshkey **keyp, char **commentp, int *perm_ok)
+{
+ int fd, r;
+
+ if (keyp != NULL)
+ *keyp = NULL;
+ if (commentp != NULL)
+ *commentp = NULL;
+
+ if ((fd = open(filename, O_RDONLY)) < 0) {
+ if (perm_ok != NULL)
+ *perm_ok = 0;
+ return SSH_ERR_SYSTEM_ERROR;
+ }
+ if (sshkey_perm_ok(fd, filename) != 0) {
+ if (perm_ok != NULL)
+ *perm_ok = 0;
+ r = SSH_ERR_KEY_BAD_PERMISSIONS;
+ goto out;
+ }
+ if (perm_ok != NULL)
+ *perm_ok = 1;
+
+ 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_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 ((buffer = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((r = sshkey_load_file(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;
+}
+
+/* XXX this is almost identical to sshkey_load_private_type() */
+int
+sshkey_load_private(const char *filename, const char *passphrase,
+ struct sshkey **keyp, char **commentp)
+{
+ struct sshbuf *buffer = NULL;
+ int r, fd;
+
+ if (keyp != NULL)
+ *keyp = NULL;
+ if (commentp != NULL)
+ *commentp = NULL;
+
+ if ((fd = open(filename, O_RDONLY)) < 0)
+ return SSH_ERR_SYSTEM_ERROR;
+ if (sshkey_perm_ok(fd, filename) != 0) {
+ r = SSH_ERR_KEY_BAD_PERMISSIONS;
+ goto out;
+ }
+
+ if ((buffer = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((r = sshkey_load_file(fd, buffer)) != 0 ||
+ (r = sshkey_parse_private_fileblob(buffer, passphrase, keyp,
+ commentp)) != 0)
+ goto out;
+ if (keyp && *keyp &&
+ (r = sshkey_set_filename(*keyp, filename)) != 0)
+ goto out;
+ r = 0;
+ out:
+ close(fd);
+ sshbuf_free(buffer);
+ return r;
+}
+
+static int
+sshkey_try_load_public(struct sshkey *k, const char *filename, char **commentp)
+{
+ FILE *f;
+ char *line = NULL, *cp;
+ size_t linesize = 0;
+ int r;
+
+ if (commentp != NULL)
+ *commentp = NULL;
+ if ((f = fopen(filename, "r")) == NULL)
+ return SSH_ERR_SYSTEM_ERROR;
+ 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;
+ }
+ free(line);
+ fclose(f);
+ return r;
+ }
+ }
+ }
+ 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)
+{
+ struct sshkey *pub = NULL;
+ char *file = NULL;
+ int r;
+
+ if (keyp != NULL)
+ *keyp = NULL;
+ if (commentp != NULL)
+ *commentp = NULL;
+
+ if ((pub = sshkey_new(KEY_UNSPEC)) == NULL)
+ return SSH_ERR_ALLOC_FAIL;
+ if ((r = sshkey_try_load_public(pub, filename, commentp)) == 0) {
+ if (keyp != NULL) {
+ *keyp = pub;
+ pub = NULL;
+ }
+ r = 0;
+ goto out;
+ }
+ sshkey_free(pub);
+
+ /* try .pub suffix */
+ if (asprintf(&file, "%s.pub", filename) == -1)
+ return SSH_ERR_ALLOC_FAIL;
+ if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((r = sshkey_try_load_public(pub, file, commentp)) == 0) {
+ if (keyp != NULL) {
+ *keyp = pub;
+ pub = NULL;
+ }
+ r = 0;
+ }
+ out:
+ free(file);
+ sshkey_free(pub);
+ 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;
+
+ if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) {
+ goto out;
+ }
+ if ((r = sshkey_try_load_public(pub, file, NULL)) != 0)
+ goto out;
+ /* success */
+ if (keyp != NULL) {
+ *keyp = pub;
+ pub = NULL;
+ }
+ r = 0;
+ out:
+ 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, int *perm_ok)
+{
+ 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, perm_ok)) != 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 certficiate 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;
+ }
+}
+
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-05 02:14:58 +0000