Sat Nov 1 06:31:11 2008

Asterisk developer's documentation

---

res_crypto.c File Reference

Provide Cryptographic Signature capability. More...

#include <sys/types.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <stdio.h>
#include <dirent.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include "asterisk.h"
#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 "asterisk/lock.h"
#include "asterisk/utils.h"

Include dependency graph for res_crypto.c:

Go to the source code of this file.

Data Structures
struct	ast_key
Defines
#define	KEY_NEEDS_PASSCODE   (1 << 16)
Functions
static int	__ast_check_signature (struct ast_key *key, const char *msg, const char *sig)
static int	__ast_check_signature_bin (struct ast_key *key, const char *msg, int msglen, const unsigned char *dsig)
static int	__ast_decrypt_bin (unsigned char *dst, const unsigned char *src, int srclen, struct ast_key *key)
static int	__ast_encrypt_bin (unsigned char *dst, const unsigned char *src, int srclen, struct ast_key *key)
static struct ast_key *	__ast_key_get (const char *kname, int ktype)
static int	__ast_sign (struct ast_key *key, char *msg, char *sig)
static int	__ast_sign_bin (struct ast_key *key, const char *msg, int msglen, unsigned char *dsig)
	AST_MUTEX_DEFINE_STATIC (keylock)
static int	crypto_init (void)
static void	crypto_load (int ifd, int ofd)
char *	description (void)
	Provides a description of the module.
static int	init_keys (int fd, int argc, char *argv[])
char *	key ()
	Returns the ASTERISK_GPL_KEY.
int	load_module (void)
	Initialize the module.
static void	md52sum (char *sum, unsigned char *md5)
static int	pw_cb (char *buf, int size, int rwflag, void *userdata)
int	reload (void)
	Reload stuff.
static int	show_keys (int fd, int argc, char *argv[])
static struct ast_key *	try_load_key (char *dir, char *fname, int ifd, int ofd, int *not2)
int	unload_module (void)
	Cleanup all module structures, sockets, etc.
int	usecount (void)
	Provides a usecount.
Variables
static struct ast_cli_entry	cli_init_keys
static struct ast_cli_entry	cli_show_keys
static char	init_keys_usage []
static struct ast_key *	keys = NULL
static char	show_key_usage []

---

Detailed Description

Provide Cryptographic Signature capability.

Definition in file res_crypto.c.

---

Define Documentation

#define KEY_NEEDS_PASSCODE   (1 << 16)

Definition at line 76 of file res_crypto.c.

Referenced by init_keys(), show_keys(), and try_load_key().

---

Function Documentation

static int __ast_check_signature	(	struct ast_key *	key,
		const char *	msg,
		const char *	sig
	)			[static]

Definition at line 441 of file res_crypto.c.

References ast_base64decode(), ast_check_signature_bin, ast_log(), key(), and LOG_WARNING.

Referenced by crypto_init().

{
   unsigned char dsig[128];
   int res;

   /* Decode signature */
   res = ast_base64decode(dsig, sig, sizeof(dsig));
   if (res != sizeof(dsig)) {
      ast_log(LOG_WARNING, "Signature improper length (expect %d, got %d)\n", (int)sizeof(dsig), (int)res);
      return -1;
   }
   res = ast_check_signature_bin(key, msg, strlen(msg), dsig);
   return res;
}

static int __ast_check_signature_bin	(	struct ast_key *	key,
		const char *	msg,
		int	msglen,
		const unsigned char *	dsig
	)			[static]

Definition at line 415 of file res_crypto.c.

References AST_KEY_PUBLIC, ast_log(), ast_key::digest, key(), LOG_DEBUG, and LOG_WARNING.

Referenced by crypto_init().

{
   unsigned char digest[20];
   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;
   }

   /* Calculate digest of message */
   SHA1((unsigned char *)msg, msglen, digest);

   /* Verify signature */
   res = RSA_verify(NID_sha1, digest, sizeof(digest), (unsigned char *)dsig, 128, key->rsa);
   
   if (!res) {
      ast_log(LOG_DEBUG, "Key failed verification: %s\n", key->name);
      return -1;
   }
   /* Pass */
   return 0;
}

static int __ast_decrypt_bin	(	unsigned char *	dst,
		const unsigned char *	src,
		int	srclen,
		struct ast_key *	key
	)			[static]

Definition at line 348 of file res_crypto.c.

References AST_KEY_PRIVATE, ast_log(), key(), LOG_NOTICE, and LOG_WARNING.

Referenced by crypto_init().

{
   int res;
   int pos = 0;
   if (key->ktype != AST_KEY_PRIVATE) {
      ast_log(LOG_WARNING, "Cannot decrypt with a public key\n");
      return -1;
   }

   if (srclen % 128) {
      ast_log(LOG_NOTICE, "Tried to decrypt something not a multiple of 128 bytes\n");
      return -1;
   }
   while(srclen) {
      /* Process chunks 128 bytes at a time */
      res = RSA_private_decrypt(128, src, dst, key->rsa, RSA_PKCS1_OAEP_PADDING);
      if (res < 0)
         return -1;
      pos += res;
      src += 128;
      srclen -= 128;
      dst += res;
   }
   return pos;
}

static int __ast_encrypt_bin	(	unsigned char *	dst,
		const unsigned char *	src,
		int	srclen,
		struct ast_key *	key
	)			[static]

Definition at line 374 of file res_crypto.c.

References AST_KEY_PUBLIC, ast_log(), key(), LOG_NOTICE, and LOG_WARNING.

Referenced by crypto_init().

{
   int res;
   int bytes;
   int pos = 0;
   if (key->ktype != AST_KEY_PUBLIC) {
      ast_log(LOG_WARNING, "Cannot encrypt with a private key\n");
      return -1;
   }
   
   while(srclen) {
      bytes = srclen;
      if (bytes > 128 - 41)
         bytes = 128 - 41;
      /* Process chunks 128-41 bytes at a time */
      res = RSA_public_encrypt(bytes, src, dst, key->rsa, RSA_PKCS1_OAEP_PADDING);
      if (res != 128) {
         ast_log(LOG_NOTICE, "How odd, encrypted size is %d\n", res);
         return -1;
      }
      src += bytes;
      srclen -= bytes;
      pos += res;
      dst += res;
   }
   return pos;
}

static struct ast_key* __ast_key_get	(	const char *	kname,
		int	ktype
	)			[static]

Definition at line 132 of file res_crypto.c.

References ast_mutex_lock(), ast_mutex_unlock(), key(), and keys.

Referenced by crypto_init().

{
   struct ast_key *key;
   ast_mutex_lock(&keylock);
   key = keys;
   while(key) {
      if (!strcmp(kname, key->name) &&
          (ktype == key->ktype))
         break;
      key = key->next;
   }
   ast_mutex_unlock(&keylock);
   return key;
}

static int __ast_sign	(	struct ast_key *	key,
		char *	msg,
		char *	sig
	)			[static]

Definition at line 402 of file res_crypto.c.

References ast_base64encode(), ast_sign_bin, and key().

Referenced by crypto_init().

{
   unsigned char dsig[128];
   int siglen = sizeof(dsig);
   int res;
   res = ast_sign_bin(key, msg, strlen(msg), dsig);
   if (!res)
      /* Success -- encode (256 bytes max as documented) */
      ast_base64encode(sig, dsig, siglen, 256);
   return res;
   
}

static int __ast_sign_bin	(	struct ast_key *	key,
		const char *	msg,
		int	msglen,
		unsigned char *	dsig
	)			[static]

Definition at line 317 of file res_crypto.c.

References AST_KEY_PRIVATE, ast_log(), ast_key::digest, key(), and LOG_WARNING.

Referenced by crypto_init().

{
   unsigned char digest[20];
   unsigned int siglen = 128;
   int res;

   if (key->ktype != AST_KEY_PRIVATE) {
      ast_log(LOG_WARNING, "Cannot sign with a public key\n");
      return -1;
   }

   /* Calculate digest of message */
   SHA1((unsigned char *)msg, msglen, 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 != 128) {
      ast_log(LOG_WARNING, "Unexpected signature length %d, expecting %d\n", (int)siglen, (int)128);
      return -1;
   }

   return 0;
   
}

AST_MUTEX_DEFINE_STATIC

(

keylock

)

static int crypto_init

(

void

)

[static]

Definition at line 568 of file res_crypto.c.

References __ast_check_signature(), __ast_check_signature_bin(), __ast_decrypt_bin(), __ast_encrypt_bin(), __ast_key_get(), __ast_sign(), __ast_sign_bin(), ast_check_signature, ast_check_signature_bin, ast_cli_register(), ast_decrypt_bin, ast_encrypt_bin, ast_key_get, ast_sign, ast_sign_bin, cli_init_keys, and cli_show_keys.

Referenced by load_module().

{
   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 void crypto_load	(	int	ifd,
		int	ofd
	)			[static]

Definition at line 456 of file res_crypto.c.

References ast_config_AST_KEY_DIR, ast_log(), ast_mutex_lock(), ast_mutex_unlock(), free, key(), keys, last, LOG_DEBUG, LOG_NOTICE, LOG_WARNING, msglist::next, and try_load_key().

Referenced by load_module(), and reload().

{
   struct ast_key *key, *nkey, *last;
   DIR *dir = NULL;
   struct dirent *ent;
   int note = 0;
   /* Mark all keys for deletion */
   ast_mutex_lock(&keylock);
   key = keys;
   while(key) {
      key->delme = 1;
      key = key->next;
   }
   ast_mutex_unlock(&keylock);
   /* Load new keys */
   dir = opendir((char *)ast_config_AST_KEY_DIR);
   if (dir) {
      while((ent = readdir(dir))) {
         try_load_key((char *)ast_config_AST_KEY_DIR, ent->d_name, ifd, ofd, &note);
      }
      closedir(dir);
   } else
      ast_log(LOG_WARNING, "Unable to open key directory '%s'\n", (char *)ast_config_AST_KEY_DIR);
   if (note) {
      ast_log(LOG_NOTICE, "Please run the command 'init keys' to enter the passcodes for the keys\n");
   }
   ast_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_mutex_unlock(&keylock);
}

char* description

(

void

)

Provides a description of the module.

Returns:

a short description of your module

Definition at line 608 of file res_crypto.c.

{
   return "Cryptographic Digital Signatures";
}

static int init_keys	(	int	fd,
		int	argc,
		char *	argv[]
	)			[static]

Definition at line 534 of file res_crypto.c.

References ast_config_AST_KEY_DIR, key(), KEY_NEEDS_PASSCODE, keys, RESULT_SUCCESS, and try_load_key().

{
   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;
}

char* key

(

void

)

Returns the ASTERISK_GPL_KEY.

This returns the ASTERISK_GPL_KEY, signifiying that you agree to the terms of the GPL stated in the ASTERISK_GPL_KEY. Your module will not load if it does not return the EXACT message:

 char *key(void) {
         return ASTERISK_GPL_KEY;
 }

Returns:

ASTERISK_GPL_KEY

Definition at line 619 of file res_crypto.c.

References ASTERISK_GPL_KEY.

{
   return ASTERISK_GPL_KEY;
}

int load_module

(

void

)

Initialize the module.

TE STUFF END

Definition at line 592 of file res_crypto.c.

References crypto_init(), crypto_load(), and option_initcrypto.

{
   crypto_init();
   if (option_initcrypto)
      crypto_load(STDIN_FILENO, STDOUT_FILENO);
   else
      crypto_load(-1, -1);
   return 0;
}

static void md52sum	(	char *	sum,
		unsigned char *	md5
	)			[static]

Definition at line 504 of file res_crypto.c.

Referenced by show_keys().

{
   int x;
   for (x=0;x<16;x++) 
      sum += sprintf(sum, "%02x", *(md5++));
}

static int pw_cb	(	char *	buf,
		int	size,
		int	rwflag,
		void *	userdata
	)			[static]

Definition at line 107 of file res_crypto.c.

References ast_hide_password(), AST_KEY_PRIVATE, ast_restore_tty(), and key().

Referenced by try_load_key().

{
   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;
}

int reload

(

void

)

Reload stuff.

This function is where any reload routines take place. Re-read config files, change signalling, whatever is appropriate on a reload.

Returns:

The return value is not used.

Definition at line 586 of file res_crypto.c.

References crypto_load().

{
   crypto_load(-1, -1);
   return 0;
}

static int show_keys	(	int	fd,
		int	argc,
		char *	argv[]
	)			[static]

Definition at line 511 of file res_crypto.c.

References ast_cli(), AST_KEY_PUBLIC, ast_mutex_lock(), ast_mutex_unlock(), key(), KEY_NEEDS_PASSCODE, keys, md52sum(), and RESULT_SUCCESS.

{
   struct ast_key *key;
   char sum[16 * 2 + 1];
   int count_keys = 0;

   ast_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;
      count_keys++;
   }
   ast_mutex_unlock(&keylock);
   ast_cli(fd, "%d known RSA keys.\n", count_keys);
   return RESULT_SUCCESS;
}

static struct ast_key* try_load_key	(	char *	dir,
		char *	fname,
		int	ifd,
		int	ofd,
		int *	not2
	)			[static]

Definition at line 147 of file res_crypto.c.

References AST_KEY_PRIVATE, AST_KEY_PUBLIC, ast_log(), ast_mutex_lock(), ast_mutex_unlock(), ast_verbose(), ast_key::digest, key(), KEY_NEEDS_PASSCODE, keys, ast_key::ktype, LOG_DEBUG, LOG_NOTICE, LOG_WARNING, malloc, MD5Final(), MD5Init(), MD5Update(), option_debug, option_initcrypto, option_verbose, pw_cb(), and VERBOSE_PREFIX_3.

Referenced by crypto_load(), and init_keys().

{
   int ktype = 0;
   char *c = NULL;
   char ffname[256];
   unsigned 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_mutex_lock(&keylock);
   key = keys;
   while(key) {
      /* Look for an existing version already */
      if (!strcasecmp(key->fn, ffname)) 
         break;
      key = key->next;
   }
   ast_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];
      memset(buf, 0, 256);
      fgets(buf, sizeof(buf), f);
      if (!feof(f)) {
         MD5Update(&md5, (unsigned char *) 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_mutex_lock(&keylock);
   /* First the filename */
   ast_copy_string(key->fn, ffname, sizeof(key->fn));
   /* Then the name */
   ast_copy_string(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) {
      if (RSA_size(key->rsa) == 128) {
         /* 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
         ast_log(LOG_NOTICE, "Key '%s' is not expected size.\n", key->name);
   } 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_mutex_unlock(&keylock);
   if (!found) {
      ast_mutex_lock(&keylock);
      key->next = keys;
      keys = key;
      ast_mutex_unlock(&keylock);
   }
   return key;
}

int unload_module

(

void

)

Cleanup all module structures, sockets, etc.

Standard module functions ...

Definition at line 602 of file res_crypto.c.

{
   /* Can't unload this once we're loaded */
   return -1;
}

int usecount

(

void

)

Provides a usecount.

This function will be called by various parts of asterisk. Basically, all it has to do is to return a usecount when called. You will need to maintain your usecount within the module somewhere. The usecount should be how many channels provided by this module are in use.

Returns:

The module's usecount.

Definition at line 613 of file res_crypto.c.

{
   /* We should never be unloaded */
   return 1;
}

---

Variable Documentation

struct ast_cli_entry cli_init_keys [static]

Initial value:

 
{ { "init", "keys", NULL }, init_keys, "Initialize RSA key passcodes", init_keys_usage }

Definition at line 565 of file res_crypto.c.

Referenced by crypto_init().

struct ast_cli_entry cli_show_keys [static]

Initial value:

 
{ { "show", "keys", NULL }, show_keys, "Displays RSA key information", show_key_usage }

Definition at line 562 of file res_crypto.c.

Referenced by crypto_init().

char init_keys_usage[] [static]

Initial value:

"Usage: init keys\n"
"       Initializes private keys (by reading in pass code from the user)\n"

Definition at line 558 of file res_crypto.c.

struct ast_key* keys = NULL [static]

Definition at line 98 of file res_crypto.c.

Referenced by __ast_key_get(), adsi_delete(), adsi_folders(), adsi_login(), adsi_message(), adsi_password(), adsi_status(), adsi_status2(), ast_db_deltree(), ast_db_gettree(), crypto_load(), database_show(), database_showkey(), init_keys(), misdn_set_opt_exec(), reply_digest(), show_keys(), and try_load_key().

char show_key_usage[] [static]

Initial value:

"Usage: show keys\n"
"       Displays information about RSA keys known by Asterisk\n"

Definition at line 554 of file res_crypto.c.

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