git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@600 65c4cc65-6c06-0410-ace0-fbb531ad65f3
639 lines
14 KiB
C
Executable file
639 lines
14 KiB
C
Executable file
/*
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* Asterisk -- A telephony toolkit for Linux.
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*
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* Provide Cryptographic Signature capability
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*
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* Copyright (C) 1999, Mark Spencer
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*
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* Mark Spencer <markster@linux-support.net>
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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
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*/
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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 <openssl/ssl.h>
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#include <openssl/err.h>
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#include <stdio.h>
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#include <pthread.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.h"
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#include "../astconf.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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static char base64[64];
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static char b2a[256];
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static pthread_mutex_t keylock = AST_MUTEX_INITIALIZER;
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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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struct ast_key *ast_key_get(char *kname, int ktype)
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{
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struct ast_key *key;
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ast_pthread_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_pthread_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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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_pthread_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_pthread_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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fgets(buf, sizeof(buf), f);
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if (!feof(f)) {
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MD5Update(&md5, 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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key = (struct ast_key *)malloc(sizeof(struct ast_key));
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if (!key) {
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ast_log(LOG_WARNING, "Out of memory\n");
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fclose(f);
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return NULL;
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}
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memset(key, 0, sizeof(struct ast_key));
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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_pthread_mutex_lock(&keylock);
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/* First the filename */
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strncpy(key->fn, ffname, sizeof(key->fn));
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/* Then the name */
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strncpy(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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/* 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 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 (!option_initcrypto)
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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_pthread_mutex_unlock(&keylock);
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if (!found) {
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ast_pthread_mutex_lock(&keylock);
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key->next = keys;
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keys = key;
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ast_pthread_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 base64decode(unsigned char *dst, char *src, int max)
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{
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int cnt = 0;
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unsigned int byte = 0;
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unsigned int bits = 0;
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int incnt = 0;
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#if 0
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unsigned char *odst = dst;
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#endif
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while(*src && (cnt < max)) {
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/* Shift in 6 bits of input */
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byte <<= 6;
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byte |= (b2a[(int)(*src)]) & 0x3f;
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bits += 6;
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#if 0
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printf("Add: %c %s\n", *src, binary(b2a[(int)(*src)] & 0x3f, 6));
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#endif
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src++;
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incnt++;
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/* If we have at least 8 bits left over, take that character
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off the top */
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if (bits >= 8) {
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bits -= 8;
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*dst = (byte >> bits) & 0xff;
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#if 0
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printf("Remove: %02x %s\n", *dst, binary(*dst, 8));
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#endif
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dst++;
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cnt++;
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}
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}
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#if 0
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dump(odst, cnt);
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#endif
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/* Dont worry about left over bits, they're extra anyway */
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return cnt;
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}
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static int base64encode(char *dst, unsigned char *src, int srclen, int max)
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{
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int cnt = 0;
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unsigned int byte = 0;
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int bits = 0;
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int index;
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int cntin = 0;
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#if 0
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char *odst = dst;
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dump(src, srclen);
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#endif
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/* Reserve one bit for end */
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max--;
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while((cntin < srclen) && (cnt < max)) {
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byte <<= 8;
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#if 0
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printf("Add: %02x %s\n", *src, binary(*src, 8));
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#endif
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byte |= *(src++);
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bits += 8;
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cntin++;
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while((bits >= 6) && (cnt < max)) {
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bits -= 6;
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/* We want only the top */
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index = (byte >> bits) & 0x3f;
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*dst = base64[index];
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#if 0
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printf("Remove: %c %s\n", *dst, binary(index, 6));
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#endif
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dst++;
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cnt++;
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}
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}
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if (bits && (cnt < max)) {
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/* Add one last character for the remaining bits,
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padding the rest with 0 */
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byte <<= (6 - bits);
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index = (byte) & 0x3f;
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*(dst++) = base64[index];
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cnt++;
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}
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*dst = '\0';
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return cnt;
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}
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int ast_sign(struct ast_key *key, char *msg, char *sig)
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{
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unsigned char digest[20];
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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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if (key->ktype != AST_KEY_PRIVATE) {
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ast_log(LOG_WARNING, "Cannot sign 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, strlen(msg), 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 != sizeof(dsig)) {
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ast_log(LOG_WARNING, "Unexpected signature length %d, expecting %d\n", siglen, sizeof(dsig));
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return -1;
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}
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/* Success -- encode (256 bytes max as documented) */
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base64encode(sig, dsig, siglen, 256);
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return 0;
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}
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int ast_check_signature(struct ast_key *key, char *msg, char *sig)
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{
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unsigned char digest[20];
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unsigned char dsig[128];
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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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/* Decode signature */
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res = 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", sizeof(dsig), res);
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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, strlen(msg), digest);
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/* Verify signature */
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res = RSA_verify(NID_sha1, digest, sizeof(digest), dsig, sizeof(dsig), key->rsa);
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if (!res) {
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ast_log(LOG_DEBUG, "Key failed verification\n");
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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 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;
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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_pthread_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_pthread_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_pthread_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_pthread_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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ast_pthread_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");
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while(key) {
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md52sum(sum, key->digest);
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ast_cli(fd, "%-18s %-8s %-16s %-33s\n", key->name,
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(key->ktype & 0xf) == AST_KEY_PUBLIC ? "PUBLIC" : "PRIVATE",
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key->ktype & KEY_NEEDS_PASSCODE ? "[Needs Passcode]" : "[Loaded]", sum);
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key = key->next;
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}
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ast_pthread_mutex_unlock(&keylock);
|
|
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;
|
|
strncpy(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 void base64_init(void)
|
|
{
|
|
int x;
|
|
memset(b2a, -1, sizeof(b2a));
|
|
/* Initialize base-64 Conversion table */
|
|
for (x=0;x<26;x++) {
|
|
/* A-Z */
|
|
base64[x] = 'A' + x;
|
|
b2a['A' + x] = x;
|
|
/* a-z */
|
|
base64[x + 26] = 'a' + x;
|
|
b2a['a' + x] = x + 26;
|
|
/* 0-9 */
|
|
if (x < 10) {
|
|
base64[x + 52] = '0' + x;
|
|
b2a['0' + x] = x + 52;
|
|
}
|
|
}
|
|
base64[62] = '+';
|
|
base64[63] = '/';
|
|
b2a[(int)'+'] = 62;
|
|
b2a[(int)'/'] = 63;
|
|
#if 0
|
|
for (x=0;x<64;x++) {
|
|
if (b2a[(int)base64[x]] != x) {
|
|
fprintf(stderr, "!!! %d failed\n", x);
|
|
} else
|
|
fprintf(stderr, "--- %d passed\n", x);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static int crypto_init(void)
|
|
{
|
|
base64_init();
|
|
SSL_library_init();
|
|
ERR_load_crypto_strings();
|
|
ast_cli_register(&cli_show_keys);
|
|
ast_cli_register(&cli_init_keys);
|
|
return 0;
|
|
}
|
|
|
|
int reload(void)
|
|
{
|
|
crypto_load(-1, -1);
|
|
return 0;
|
|
}
|
|
|
|
int load_module(void)
|
|
{
|
|
crypto_init();
|
|
if (option_initcrypto)
|
|
crypto_load(STDIN_FILENO, STDOUT_FILENO);
|
|
else
|
|
crypto_load(-1, -1);
|
|
return 0;
|
|
}
|
|
|
|
int unload_module(void)
|
|
{
|
|
/* Can't unload this once we're loaded */
|
|
return -1;
|
|
}
|
|
|
|
char *description(void)
|
|
{
|
|
return "Cryptographic Digital Signatures";
|
|
}
|
|
|
|
int usecount(void)
|
|
{
|
|
/* We should never be unloaded */
|
|
return 1;
|
|
}
|
|
|
|
char *key()
|
|
{
|
|
return ASTERISK_GPL_KEY;
|
|
}
|