diff options
author | markster <markster@f38db490-d61c-443f-a65b-d21fe96a405b> | 2001-12-25 21:12:07 +0000 |
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committer | markster <markster@f38db490-d61c-443f-a65b-d21fe96a405b> | 2001-12-25 21:12:07 +0000 |
commit | 2ec0e7173627c60082309f3b4bed31a4d4350bf2 (patch) | |
tree | 478308e9771ec6ebdffba099906fc57c0b9bae7a /res/res_crypto.c | |
parent | f3a2afa02ecccbf4300c74b832248630a761df6a (diff) |
Version 0.1.10 from FTP
git-svn-id: http://svn.digium.com/svn/asterisk/trunk@396 f38db490-d61c-443f-a65b-d21fe96a405b
Diffstat (limited to 'res/res_crypto.c')
-rwxr-xr-x | res/res_crypto.c | 633 |
1 files changed, 633 insertions, 0 deletions
diff --git a/res/res_crypto.c b/res/res_crypto.c new file mode 100755 index 000000000..8aa4e9d6e --- /dev/null +++ b/res/res_crypto.c @@ -0,0 +1,633 @@ +/* + * Asterisk -- A telephony toolkit for Linux. + * + * Provide Cryptographic Signature capability + * + * Copyright (C) 1999, Mark Spencer + * + * Mark Spencer <markster@linux-support.net> + * + * This program is free software, distributed under the terms of + * the GNU General Public License + */ + +#include <asterisk/file.h> +#include <asterisk/channel.h> +#include <asterisk/logger.h> +#include <asterisk/say.h> +#include <asterisk/module.h> +#include <asterisk/options.h> +#include <asterisk/crypto.h> +#include <asterisk/md5.h> +#include <asterisk/cli.h> +#include <asterisk/io.h> +#include <openssl/ssl.h> +#include <openssl/err.h> +#include <stdio.h> +#include <pthread.h> +#include <dirent.h> +#include <string.h> +#include <errno.h> +#include "../asterisk.h" + +/* + * Asterisk uses RSA keys with SHA-1 message digests for its + * digital signatures. The choice of RSA is due to its higher + * throughput on verification, and the choice of SHA-1 based + * on the recently discovered collisions in MD5's compression + * algorithm and recommendations of avoiding MD5 in new schemes + * from various industry experts. + * + * We use OpenSSL to provide our crypto routines, although we never + * actually use full-up SSL + * + */ + +/* + * XXX This module is not very thread-safe. It is for everyday stuff + * like reading keys and stuff, but there are all kinds of weird + * races with people running reload and key init at the same time + * for example + * + * XXXX + */ + +static char base64[64]; +static char b2a[256]; + +static pthread_mutex_t keylock = PTHREAD_MUTEX_INITIALIZER; + +#define KEY_NEEDS_PASSCODE (1 << 16) + +struct ast_key { + /* Name of entity */ + char name[80]; + /* File name */ + char fn[256]; + /* Key type (AST_KEY_PUB or AST_KEY_PRIV, along with flags from above) */ + int ktype; + /* RSA structure (if successfully loaded) */ + RSA *rsa; + /* Whether we should be deleted */ + int delme; + /* FD for input (or -1 if no input allowed, or -2 if we needed input) */ + int infd; + /* FD for output */ + int outfd; + /* Last MD5 Digest */ + unsigned char digest[16]; + struct ast_key *next; +}; + +static struct ast_key *keys = NULL; + +static int fdprint(int fd, char *s) +{ + return write(fd, s, strlen(s) + 1); +} + +static int pw_cb(char *buf, int size, int rwflag, void *userdata) +{ + struct ast_key *key = (struct ast_key *)userdata; + char prompt[256]; + int res; + int tmp; + if (key->infd > -1) { + snprintf(prompt, sizeof(prompt), ">>>> passcode for %s key '%s': ", + key->ktype == AST_KEY_PRIVATE ? "PRIVATE" : "PUBLIC", key->name); + write(key->outfd, prompt, strlen(prompt)); + memset(buf, 0, sizeof(buf)); + tmp = ast_hide_password(key->infd); + memset(buf, 0, size); + res = read(key->infd, buf, size); + ast_restore_tty(key->infd, tmp); + if (buf[strlen(buf) -1] == '\n') + buf[strlen(buf) - 1] = '\0'; + return strlen(buf); + } else { + /* Note that we were at least called */ + key->infd = -2; + } + return -1; +} + +struct ast_key *ast_key_get(char *kname, int ktype) +{ + struct ast_key *key; + ast_pthread_mutex_lock(&keylock); + key = keys; + while(key) { + if (!strcmp(kname, key->name) && + (ktype == key->ktype)) + break; + key = key->next; + } + ast_pthread_mutex_unlock(&keylock); + return key; +} + +static struct ast_key *try_load_key (char *dir, char *fname, int ifd, int ofd, int *not2) +{ + int ktype = 0; + char *c = NULL; + char ffname[256]; + char digest[16]; + FILE *f; + struct MD5Context md5; + struct ast_key *key; + static int notice = 0; + int found = 0; + + /* Make sure its name is a public or private key */ + + if ((c = strstr(fname, ".pub")) && !strcmp(c, ".pub")) { + ktype = AST_KEY_PUBLIC; + } else if ((c = strstr(fname, ".key")) && !strcmp(c, ".key")) { + ktype = AST_KEY_PRIVATE; + } else + return NULL; + + /* Get actual filename */ + snprintf(ffname, sizeof(ffname), "%s/%s", dir, fname); + + ast_pthread_mutex_lock(&keylock); + key = keys; + while(key) { + /* Look for an existing version already */ + if (!strcasecmp(key->fn, ffname)) + break; + key = key->next; + } + ast_pthread_mutex_unlock(&keylock); + + /* Open file */ + f = fopen(ffname, "r"); + if (!f) { + ast_log(LOG_WARNING, "Unable to open key file %s: %s\n", ffname, strerror(errno)); + return NULL; + } + MD5Init(&md5); + while(!feof(f)) { + /* Calculate a "whatever" quality md5sum of the key */ + char buf[256]; + fgets(buf, sizeof(buf), f); + if (!feof(f)) { + MD5Update(&md5, buf, strlen(buf)); + } + } + MD5Final(digest, &md5); + if (key) { + /* If the MD5 sum is the same, and it isn't awaiting a passcode + then this is far enough */ + if (!memcmp(digest, key->digest, 16) && + !(key->ktype & KEY_NEEDS_PASSCODE)) { + fclose(f); + key->delme = 0; + return NULL; + } else { + /* Preserve keytype */ + ktype = key->ktype; + /* Recycle the same structure */ + found++; + } + } + + /* Make fname just be the normal name now */ + *c = '\0'; + if (!key) { + key = (struct ast_key *)malloc(sizeof(struct ast_key)); + if (!key) { + ast_log(LOG_WARNING, "Out of memory\n"); + fclose(f); + return NULL; + } + memset(key, 0, sizeof(struct ast_key)); + } + /* At this point we have a key structure (old or new). Time to + fill it with what we know */ + /* Gotta lock if this one already exists */ + if (found) + ast_pthread_mutex_lock(&keylock); + /* First the filename */ + strncpy(key->fn, ffname, sizeof(key->fn)); + /* Then the name */ + strncpy(key->name, fname, sizeof(key->name)); + key->ktype = ktype; + /* Yes, assume we're going to be deleted */ + key->delme = 1; + /* Keep the key type */ + memcpy(key->digest, digest, 16); + /* Can I/O takes the FD we're given */ + key->infd = ifd; + key->outfd = ofd; + /* Reset the file back to the beginning */ + rewind(f); + /* Now load the key with the right method */ + if (ktype == AST_KEY_PUBLIC) + key->rsa = PEM_read_RSA_PUBKEY(f, NULL, pw_cb, key); + else + key->rsa = PEM_read_RSAPrivateKey(f, NULL, pw_cb, key); + fclose(f); + if (key->rsa) { + /* Key loaded okay */ + key->ktype &= ~KEY_NEEDS_PASSCODE; + if (option_verbose > 2) + ast_verbose(VERBOSE_PREFIX_3 "Loaded %s key '%s'\n", key->ktype == AST_KEY_PUBLIC ? "PUBLIC" : "PRIVATE", key->name); + if (option_debug) + ast_log(LOG_DEBUG, "Key '%s' loaded OK\n", key->name); + key->delme = 0; + } else if (key->infd != -2) { + ast_log(LOG_WARNING, "Key load %s '%s' failed\n",key->ktype == AST_KEY_PUBLIC ? "PUBLIC" : "PRIVATE", key->name); + if (ofd > -1) { + ERR_print_errors_fp(stderr); + } else + ERR_print_errors_fp(stderr); + } else { + ast_log(LOG_NOTICE, "Key '%s' needs passcode.\n", key->name); + key->ktype |= KEY_NEEDS_PASSCODE; + if (!notice) { + if (!option_initcrypto) + ast_log(LOG_NOTICE, "Add the '-i' flag to the asterisk command line if you want to automatically initialize passcodes at launch.\n"); + notice++; + } + /* Keep it anyway */ + key->delme = 0; + /* Print final notice about "init keys" when done */ + *not2 = 1; + } + if (found) + ast_pthread_mutex_unlock(&keylock); + if (!found) { + ast_pthread_mutex_lock(&keylock); + key->next = keys; + keys = key; + ast_pthread_mutex_unlock(&keylock); + } + return key; +} + +#if 0 + +static void dump(unsigned char *src, int len) +{ + int x; + for (x=0;x<len;x++) + printf("%02x", *(src++)); + printf("\n"); +} + +static char *binary(int y, int len) +{ + static char res[80]; + int x; + memset(res, 0, sizeof(res)); + for (x=0;x<len;x++) { + if (y & (1 << x)) + res[(len - x - 1)] = '1'; + else + res[(len - x - 1)] = '0'; + } + return res; +} + +#endif + +static int base64decode(unsigned char *dst, char *src, int max) +{ + int cnt = 0; + unsigned int byte = 0; + unsigned int bits = 0; + int incnt = 0; +#if 0 + unsigned char *odst = dst; +#endif + while(*src && (cnt < max)) { + /* Shift in 6 bits of input */ + byte <<= 6; + byte |= (b2a[(int)(*src)]) & 0x3f; + bits += 6; +#if 0 + printf("Add: %c %s\n", *src, binary(b2a[(int)(*src)] & 0x3f, 6)); +#endif + src++; + incnt++; + /* If we have at least 8 bits left over, take that character + off the top */ + if (bits >= 8) { + bits -= 8; + *dst = (byte >> bits) & 0xff; +#if 0 + printf("Remove: %02x %s\n", *dst, binary(*dst, 8)); +#endif + dst++; + cnt++; + } + } +#if 0 + dump(odst, cnt); +#endif + /* Dont worry about left over bits, they're extra anyway */ + return cnt; +} + +static int base64encode(char *dst, unsigned char *src, int srclen, int max) +{ + int cnt = 0; + unsigned int byte = 0; + int bits = 0; + int index; + int cntin = 0; +#if 0 + char *odst = dst; + dump(src, srclen); +#endif + /* Reserve one bit for end */ + max--; + while((cntin < srclen) && (cnt < max)) { + byte <<= 8; +#if 0 + printf("Add: %02x %s\n", *src, binary(*src, 8)); +#endif + byte |= *(src++); + bits += 8; + cntin++; + while((bits >= 6) && (cnt < max)) { + bits -= 6; + /* We want only the top */ + index = (byte >> bits) & 0x3f; + *dst = base64[index]; +#if 0 + printf("Remove: %c %s\n", *dst, binary(index, 6)); +#endif + dst++; + cnt++; + } + } + if (bits && (cnt < max)) { + /* Add one last character for the remaining bits, + padding the rest with 0 */ + byte <<= (6 - bits); + index = (byte) & 0x3f; + *(dst++) = base64[index]; + cnt++; + } + *dst = '\0'; + return cnt; +} + +int ast_sign(struct ast_key *key, char *msg, char *sig) +{ + unsigned char digest[20]; + unsigned char dsig[128]; + int siglen = sizeof(dsig); + int res; + + if (key->ktype != AST_KEY_PRIVATE) { + ast_log(LOG_WARNING, "Cannot sign with a private key\n"); + return -1; + } + + /* Calculate digest of message */ + SHA1((unsigned char *)msg, strlen(msg), digest); + + /* Verify signature */ + res = RSA_sign(NID_sha1, digest, sizeof(digest), dsig, &siglen, key->rsa); + + if (!res) { + ast_log(LOG_WARNING, "RSA Signature (key %s) failed\n", key->name); + return -1; + } + + if (siglen != sizeof(dsig)) { + ast_log(LOG_WARNING, "Unexpected signature length %d, expecting %d\n", siglen, sizeof(dsig)); + return -1; + } + + /* Success -- encode (256 bytes max as documented) */ + base64encode(sig, dsig, siglen, 256); + return 0; + +} + +int ast_check_signature(struct ast_key *key, char *msg, char *sig) +{ + unsigned char digest[20]; + unsigned char dsig[128]; + int res; + + if (key->ktype != AST_KEY_PUBLIC) { + /* Okay, so of course you really *can* but for our purposes + we're going to say you can't */ + ast_log(LOG_WARNING, "Cannot check message signature with a private key\n"); + return -1; + } + + /* Decode signature */ + res = base64decode(dsig, sig, sizeof(dsig)); + if (res != sizeof(dsig)) { + ast_log(LOG_WARNING, "Signature improper length (expect %d, got %d)\n", sizeof(dsig), res); + return -1; + } + + /* Calculate digest of message */ + SHA1((unsigned char *)msg, strlen(msg), digest); + + /* Verify signature */ + res = RSA_verify(NID_sha1, digest, sizeof(digest), dsig, sizeof(dsig), key->rsa); + + if (!res) { + ast_log(LOG_DEBUG, "Key failed verification\n"); + return -1; + } + /* Pass */ + return 0; +} + +static void crypto_load(int ifd, int ofd) +{ + struct ast_key *key, *nkey, *last; + DIR *dir; + struct dirent *ent; + int note = 0; + /* Mark all keys for deletion */ + ast_pthread_mutex_lock(&keylock); + key = keys; + while(key) { + key->delme = 1; + key = key->next; + } + ast_pthread_mutex_unlock(&keylock); + /* Load new keys */ + dir = opendir(AST_KEY_DIR); + if (dir) { + while((ent = readdir(dir))) { + try_load_key(AST_KEY_DIR, ent->d_name, ifd, ofd, ¬e); + } + closedir(dir); + } else + ast_log(LOG_WARNING, "Unable to open key directory '%s'\n", AST_KEY_DIR); + if (note) { + ast_log(LOG_NOTICE, "Please run the command 'init keys' to enter the passcodes for the keys\n"); + } + ast_pthread_mutex_lock(&keylock); + key = keys; + last = NULL; + while(key) { + nkey = key->next; + if (key->delme) { + ast_log(LOG_DEBUG, "Deleting key %s type %d\n", key->name, key->ktype); + /* Do the delete */ + if (last) + last->next = nkey; + else + keys = nkey; + if (key->rsa) + RSA_free(key->rsa); + free(key); + } else + last = key; + key = nkey; + } + ast_pthread_mutex_unlock(&keylock); +} + +static void md52sum(char *sum, unsigned char *md5) +{ + int x; + for (x=0;x<16;x++) + sum += sprintf(sum, "%02x", *(md5++)); +} + +static int show_keys(int fd, int argc, char *argv[]) +{ + struct ast_key *key; + char sum[16 * 2 + 1]; + + ast_pthread_mutex_lock(&keylock); + key = keys; + 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; + } + 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_KEY_DIR) + 1; + strncpy(tmp, kn, sizeof(tmp)); + try_load_key(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; +} |