git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@32846 65c4cc65-6c06-0410-ace0-fbb531ad65f3
622 lines
15 KiB
C
622 lines
15 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 1999 - 2005, Digium, Inc.
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*
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* Mark Spencer <markster@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief Provide Cryptographic Signature capability
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*
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* \author Mark Spencer <markster@digium.com>
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*/
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/*** MODULEINFO
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<depend>ssl</depend>
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***/
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#include "asterisk.h"
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ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
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#include <sys/types.h>
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#include <openssl/ssl.h>
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#include <openssl/err.h>
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#include <stdio.h>
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#include <dirent.h>
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include "asterisk/file.h"
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#include "asterisk/channel.h"
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#include "asterisk/logger.h"
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#include "asterisk/say.h"
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#include "asterisk/module.h"
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#include "asterisk/options.h"
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#include "asterisk/crypto.h"
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#include "asterisk/md5.h"
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#include "asterisk/cli.h"
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#include "asterisk/io.h"
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#include "asterisk/lock.h"
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#include "asterisk/utils.h"
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/*
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* Asterisk uses RSA keys with SHA-1 message digests for its
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* digital signatures. The choice of RSA is due to its higher
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* throughput on verification, and the choice of SHA-1 based
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* on the recently discovered collisions in MD5's compression
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* algorithm and recommendations of avoiding MD5 in new schemes
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* from various industry experts.
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*
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* We use OpenSSL to provide our crypto routines, although we never
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* actually use full-up SSL
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*
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*/
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/*
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* XXX This module is not very thread-safe. It is for everyday stuff
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* like reading keys and stuff, but there are all kinds of weird
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* races with people running reload and key init at the same time
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* for example
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*
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* XXXX
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*/
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AST_MUTEX_DEFINE_STATIC(keylock);
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#define KEY_NEEDS_PASSCODE (1 << 16)
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struct ast_key {
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/* Name of entity */
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char name[80];
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/* File name */
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char fn[256];
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/* Key type (AST_KEY_PUB or AST_KEY_PRIV, along with flags from above) */
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int ktype;
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/* RSA structure (if successfully loaded) */
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RSA *rsa;
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/* Whether we should be deleted */
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int delme;
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/* FD for input (or -1 if no input allowed, or -2 if we needed input) */
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int infd;
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/* FD for output */
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int outfd;
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/* Last MD5 Digest */
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unsigned char digest[16];
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struct ast_key *next;
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};
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static struct ast_key *keys = NULL;
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#if 0
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static int fdprint(int fd, char *s)
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{
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return write(fd, s, strlen(s) + 1);
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}
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#endif
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static int pw_cb(char *buf, int size, int rwflag, void *userdata)
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{
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struct ast_key *key = (struct ast_key *)userdata;
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char prompt[256];
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int res;
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int tmp;
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if (key->infd > -1) {
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snprintf(prompt, sizeof(prompt), ">>>> passcode for %s key '%s': ",
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key->ktype == AST_KEY_PRIVATE ? "PRIVATE" : "PUBLIC", key->name);
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write(key->outfd, prompt, strlen(prompt));
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memset(buf, 0, sizeof(buf));
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tmp = ast_hide_password(key->infd);
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memset(buf, 0, size);
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res = read(key->infd, buf, size);
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ast_restore_tty(key->infd, tmp);
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if (buf[strlen(buf) -1] == '\n')
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buf[strlen(buf) - 1] = '\0';
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return strlen(buf);
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} else {
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/* Note that we were at least called */
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key->infd = -2;
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}
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return -1;
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}
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static struct ast_key *__ast_key_get(const char *kname, int ktype)
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{
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struct ast_key *key;
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ast_mutex_lock(&keylock);
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key = keys;
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while(key) {
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if (!strcmp(kname, key->name) &&
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(ktype == key->ktype))
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break;
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key = key->next;
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}
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ast_mutex_unlock(&keylock);
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return key;
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}
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static struct ast_key *try_load_key (char *dir, char *fname, int ifd, int ofd, int *not2)
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{
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int ktype = 0;
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char *c = NULL;
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char ffname[256];
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unsigned char digest[16];
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FILE *f;
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struct MD5Context md5;
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struct ast_key *key;
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static int notice = 0;
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int found = 0;
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/* Make sure its name is a public or private key */
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if ((c = strstr(fname, ".pub")) && !strcmp(c, ".pub")) {
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ktype = AST_KEY_PUBLIC;
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} else if ((c = strstr(fname, ".key")) && !strcmp(c, ".key")) {
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ktype = AST_KEY_PRIVATE;
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} else
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return NULL;
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/* Get actual filename */
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snprintf(ffname, sizeof(ffname), "%s/%s", dir, fname);
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ast_mutex_lock(&keylock);
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key = keys;
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while(key) {
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/* Look for an existing version already */
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if (!strcasecmp(key->fn, ffname))
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break;
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key = key->next;
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}
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ast_mutex_unlock(&keylock);
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/* Open file */
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f = fopen(ffname, "r");
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if (!f) {
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ast_log(LOG_WARNING, "Unable to open key file %s: %s\n", ffname, strerror(errno));
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return NULL;
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}
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MD5Init(&md5);
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while(!feof(f)) {
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/* Calculate a "whatever" quality md5sum of the key */
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char buf[256];
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memset(buf, 0, 256);
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fgets(buf, sizeof(buf), f);
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if (!feof(f)) {
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MD5Update(&md5, (unsigned char *) buf, strlen(buf));
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}
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}
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MD5Final(digest, &md5);
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if (key) {
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/* If the MD5 sum is the same, and it isn't awaiting a passcode
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then this is far enough */
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if (!memcmp(digest, key->digest, 16) &&
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!(key->ktype & KEY_NEEDS_PASSCODE)) {
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fclose(f);
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key->delme = 0;
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return NULL;
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} else {
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/* Preserve keytype */
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ktype = key->ktype;
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/* Recycle the same structure */
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found++;
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}
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}
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/* Make fname just be the normal name now */
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*c = '\0';
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if (!key) {
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if (!(key = ast_calloc(1, sizeof(*key)))) {
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fclose(f);
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return NULL;
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}
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}
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/* At this point we have a key structure (old or new). Time to
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fill it with what we know */
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/* Gotta lock if this one already exists */
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if (found)
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ast_mutex_lock(&keylock);
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/* First the filename */
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ast_copy_string(key->fn, ffname, sizeof(key->fn));
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/* Then the name */
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ast_copy_string(key->name, fname, sizeof(key->name));
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key->ktype = ktype;
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/* Yes, assume we're going to be deleted */
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key->delme = 1;
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/* Keep the key type */
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memcpy(key->digest, digest, 16);
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/* Can I/O takes the FD we're given */
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key->infd = ifd;
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key->outfd = ofd;
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/* Reset the file back to the beginning */
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rewind(f);
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/* Now load the key with the right method */
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if (ktype == AST_KEY_PUBLIC)
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key->rsa = PEM_read_RSA_PUBKEY(f, NULL, pw_cb, key);
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else
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key->rsa = PEM_read_RSAPrivateKey(f, NULL, pw_cb, key);
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fclose(f);
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if (key->rsa) {
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if (RSA_size(key->rsa) == 128) {
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/* Key loaded okay */
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key->ktype &= ~KEY_NEEDS_PASSCODE;
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if (option_verbose > 2)
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ast_verbose(VERBOSE_PREFIX_3 "Loaded %s key '%s'\n", key->ktype == AST_KEY_PUBLIC ? "PUBLIC" : "PRIVATE", key->name);
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if (option_debug)
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ast_log(LOG_DEBUG, "Key '%s' loaded OK\n", key->name);
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key->delme = 0;
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} else
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ast_log(LOG_NOTICE, "Key '%s' is not expected size.\n", key->name);
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} else if (key->infd != -2) {
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ast_log(LOG_WARNING, "Key load %s '%s' failed\n",key->ktype == AST_KEY_PUBLIC ? "PUBLIC" : "PRIVATE", key->name);
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if (ofd > -1) {
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ERR_print_errors_fp(stderr);
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} else
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ERR_print_errors_fp(stderr);
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} else {
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ast_log(LOG_NOTICE, "Key '%s' needs passcode.\n", key->name);
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key->ktype |= KEY_NEEDS_PASSCODE;
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if (!notice) {
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if (!ast_opt_init_keys)
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ast_log(LOG_NOTICE, "Add the '-i' flag to the asterisk command line if you want to automatically initialize passcodes at launch.\n");
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notice++;
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}
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/* Keep it anyway */
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key->delme = 0;
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/* Print final notice about "init keys" when done */
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*not2 = 1;
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}
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if (found)
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ast_mutex_unlock(&keylock);
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if (!found) {
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ast_mutex_lock(&keylock);
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key->next = keys;
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keys = key;
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ast_mutex_unlock(&keylock);
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}
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return key;
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}
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#if 0
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static void dump(unsigned char *src, int len)
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{
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int x;
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for (x=0;x<len;x++)
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printf("%02x", *(src++));
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printf("\n");
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}
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static char *binary(int y, int len)
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{
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static char res[80];
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int x;
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memset(res, 0, sizeof(res));
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for (x=0;x<len;x++) {
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if (y & (1 << x))
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res[(len - x - 1)] = '1';
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else
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res[(len - x - 1)] = '0';
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}
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return res;
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}
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#endif
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static int __ast_sign_bin(struct ast_key *key, const char *msg, int msglen, unsigned char *dsig)
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{
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unsigned char digest[20];
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unsigned int siglen = 128;
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int res;
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if (key->ktype != AST_KEY_PRIVATE) {
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ast_log(LOG_WARNING, "Cannot sign with a public key\n");
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return -1;
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}
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/* Calculate digest of message */
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SHA1((unsigned char *)msg, msglen, digest);
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/* Verify signature */
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res = RSA_sign(NID_sha1, digest, sizeof(digest), dsig, &siglen, key->rsa);
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if (!res) {
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ast_log(LOG_WARNING, "RSA Signature (key %s) failed\n", key->name);
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return -1;
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}
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if (siglen != 128) {
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ast_log(LOG_WARNING, "Unexpected signature length %d, expecting %d\n", (int)siglen, (int)128);
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return -1;
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}
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return 0;
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}
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static int __ast_decrypt_bin(unsigned char *dst, const unsigned char *src, int srclen, struct ast_key *key)
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{
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int res;
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int pos = 0;
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if (key->ktype != AST_KEY_PRIVATE) {
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ast_log(LOG_WARNING, "Cannot decrypt with a public key\n");
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return -1;
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}
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if (srclen % 128) {
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ast_log(LOG_NOTICE, "Tried to decrypt something not a multiple of 128 bytes\n");
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return -1;
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}
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while(srclen) {
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/* Process chunks 128 bytes at a time */
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res = RSA_private_decrypt(128, src, dst, key->rsa, RSA_PKCS1_OAEP_PADDING);
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if (res < 0)
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return -1;
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pos += res;
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src += 128;
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srclen -= 128;
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dst += res;
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}
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return pos;
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}
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static int __ast_encrypt_bin(unsigned char *dst, const unsigned char *src, int srclen, struct ast_key *key)
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{
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int res;
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int bytes;
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int pos = 0;
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if (key->ktype != AST_KEY_PUBLIC) {
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ast_log(LOG_WARNING, "Cannot encrypt with a private key\n");
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return -1;
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}
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while(srclen) {
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bytes = srclen;
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if (bytes > 128 - 41)
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bytes = 128 - 41;
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/* Process chunks 128-41 bytes at a time */
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res = RSA_public_encrypt(bytes, src, dst, key->rsa, RSA_PKCS1_OAEP_PADDING);
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if (res != 128) {
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ast_log(LOG_NOTICE, "How odd, encrypted size is %d\n", res);
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return -1;
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}
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src += bytes;
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srclen -= bytes;
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pos += res;
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dst += res;
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}
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return pos;
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}
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static int __ast_sign(struct ast_key *key, char *msg, char *sig)
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{
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unsigned char dsig[128];
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int siglen = sizeof(dsig);
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int res;
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res = ast_sign_bin(key, msg, strlen(msg), dsig);
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if (!res)
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/* Success -- encode (256 bytes max as documented) */
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ast_base64encode(sig, dsig, siglen, 256);
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return res;
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}
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static int __ast_check_signature_bin(struct ast_key *key, const char *msg, int msglen, const unsigned char *dsig)
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{
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unsigned char digest[20];
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int res;
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if (key->ktype != AST_KEY_PUBLIC) {
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/* Okay, so of course you really *can* but for our purposes
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we're going to say you can't */
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ast_log(LOG_WARNING, "Cannot check message signature with a private key\n");
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return -1;
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}
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/* Calculate digest of message */
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SHA1((unsigned char *)msg, msglen, digest);
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/* Verify signature */
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res = RSA_verify(NID_sha1, digest, sizeof(digest), (unsigned char *)dsig, 128, key->rsa);
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if (!res) {
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ast_log(LOG_DEBUG, "Key failed verification: %s\n", key->name);
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return -1;
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}
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/* Pass */
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return 0;
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}
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static int __ast_check_signature(struct ast_key *key, const char *msg, const char *sig)
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{
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unsigned char dsig[128];
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int res;
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/* Decode signature */
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res = ast_base64decode(dsig, sig, sizeof(dsig));
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if (res != sizeof(dsig)) {
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ast_log(LOG_WARNING, "Signature improper length (expect %d, got %d)\n", (int)sizeof(dsig), (int)res);
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return -1;
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}
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res = ast_check_signature_bin(key, msg, strlen(msg), dsig);
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return res;
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}
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static void crypto_load(int ifd, int ofd)
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{
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struct ast_key *key, *nkey, *last;
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DIR *dir = NULL;
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struct dirent *ent;
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int note = 0;
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/* Mark all keys for deletion */
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ast_mutex_lock(&keylock);
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key = keys;
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while(key) {
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key->delme = 1;
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key = key->next;
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}
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ast_mutex_unlock(&keylock);
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/* Load new keys */
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dir = opendir((char *)ast_config_AST_KEY_DIR);
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if (dir) {
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while((ent = readdir(dir))) {
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try_load_key((char *)ast_config_AST_KEY_DIR, ent->d_name, ifd, ofd, ¬e);
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}
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closedir(dir);
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} else
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ast_log(LOG_WARNING, "Unable to open key directory '%s'\n", (char *)ast_config_AST_KEY_DIR);
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if (note) {
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ast_log(LOG_NOTICE, "Please run the command 'init keys' to enter the passcodes for the keys\n");
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}
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ast_mutex_lock(&keylock);
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key = keys;
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last = NULL;
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while(key) {
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nkey = key->next;
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if (key->delme) {
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ast_log(LOG_DEBUG, "Deleting key %s type %d\n", key->name, key->ktype);
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/* Do the delete */
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if (last)
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last->next = nkey;
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else
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keys = nkey;
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if (key->rsa)
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RSA_free(key->rsa);
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free(key);
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} else
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last = key;
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key = nkey;
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}
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ast_mutex_unlock(&keylock);
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}
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static void md52sum(char *sum, unsigned char *md5)
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{
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int x;
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for (x=0;x<16;x++)
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sum += sprintf(sum, "%02x", *(md5++));
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}
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static int show_keys(int fd, int argc, char *argv[])
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{
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struct ast_key *key;
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char sum[16 * 2 + 1];
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int count_keys = 0;
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ast_mutex_lock(&keylock);
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key = keys;
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ast_cli(fd, "%-18s %-8s %-16s %-33s\n", "Key Name", "Type", "Status", "Sum");
|
|
while(key) {
|
|
md52sum(sum, key->digest);
|
|
ast_cli(fd, "%-18s %-8s %-16s %-33s\n", key->name,
|
|
(key->ktype & 0xf) == AST_KEY_PUBLIC ? "PUBLIC" : "PRIVATE",
|
|
key->ktype & KEY_NEEDS_PASSCODE ? "[Needs Passcode]" : "[Loaded]", sum);
|
|
|
|
key = key->next;
|
|
count_keys++;
|
|
}
|
|
ast_mutex_unlock(&keylock);
|
|
ast_cli(fd, "%d known RSA keys.\n", count_keys);
|
|
return RESULT_SUCCESS;
|
|
}
|
|
|
|
static int init_keys(int fd, int argc, char *argv[])
|
|
{
|
|
struct ast_key *key;
|
|
int ign;
|
|
char *kn;
|
|
char tmp[256] = "";
|
|
|
|
key = keys;
|
|
while(key) {
|
|
/* Reload keys that need pass codes now */
|
|
if (key->ktype & KEY_NEEDS_PASSCODE) {
|
|
kn = key->fn + strlen(ast_config_AST_KEY_DIR) + 1;
|
|
ast_copy_string(tmp, kn, sizeof(tmp));
|
|
try_load_key((char *)ast_config_AST_KEY_DIR, tmp, fd, fd, &ign);
|
|
}
|
|
key = key->next;
|
|
}
|
|
return RESULT_SUCCESS;
|
|
}
|
|
|
|
static char show_key_usage[] =
|
|
"Usage: show keys\n"
|
|
" Displays information about RSA keys known by Asterisk\n";
|
|
|
|
static char init_keys_usage[] =
|
|
"Usage: init keys\n"
|
|
" Initializes private keys (by reading in pass code from the user)\n";
|
|
|
|
static struct ast_cli_entry cli_show_keys =
|
|
{ { "show", "keys", NULL }, show_keys, "Displays RSA key information", show_key_usage };
|
|
|
|
static struct ast_cli_entry cli_init_keys =
|
|
{ { "init", "keys", NULL }, init_keys, "Initialize RSA key passcodes", init_keys_usage };
|
|
|
|
static int crypto_init(void)
|
|
{
|
|
SSL_library_init();
|
|
ERR_load_crypto_strings();
|
|
ast_cli_register(&cli_show_keys);
|
|
ast_cli_register(&cli_init_keys);
|
|
|
|
/* Install ourselves into stubs */
|
|
ast_key_get = __ast_key_get;
|
|
ast_check_signature = __ast_check_signature;
|
|
ast_check_signature_bin = __ast_check_signature_bin;
|
|
ast_sign = __ast_sign;
|
|
ast_sign_bin = __ast_sign_bin;
|
|
ast_encrypt_bin = __ast_encrypt_bin;
|
|
ast_decrypt_bin = __ast_decrypt_bin;
|
|
return 0;
|
|
}
|
|
|
|
static int reload(void *mod)
|
|
{
|
|
crypto_load(-1, -1);
|
|
return 0;
|
|
}
|
|
|
|
static int load_module(void *mod)
|
|
{
|
|
crypto_init();
|
|
if (ast_opt_init_keys)
|
|
crypto_load(STDIN_FILENO, STDOUT_FILENO);
|
|
else
|
|
crypto_load(-1, -1);
|
|
return 0;
|
|
}
|
|
|
|
static int unload_module(void *mod)
|
|
{
|
|
/* Can't unload this once we're loaded */
|
|
return -1;
|
|
}
|
|
|
|
static const char *description(void)
|
|
{
|
|
return "Cryptographic Digital Signatures";
|
|
}
|
|
|
|
static const char *key(void)
|
|
{
|
|
return ASTERISK_GPL_KEY;
|
|
}
|
|
|
|
STD_MOD(MOD_0 | NO_USECOUNT | NO_UNLOAD, reload, NULL, NULL);
|
|
|