src/context.c

/*--------------------------------------------------------------------------
 * LuaSec 0.4
 * Copyright (C) 2006-2009 Bruno Silvestre
 *
 *--------------------------------------------------------------------------*/

#include <string.h>
#include <openssl/ssl.h>
#include <openssl/err.h>

#include <lua.h>
#include <lauxlib.h>

#include "context.h"

struct ssl_option_s {
  const char *name;
  unsigned long code;
};
typedef struct ssl_option_s ssl_option_t;

/* index into the SSL storage where the context is.
 * see SSL_CTX_get_ex_data().
 */
static int luasec_sslctx_idx = -1;

/* The export DH key */
static DH *dh_512    = NULL;
/* The larger key (builtin is 2048, caller may specify larger) */
static DH *dh_larger = NULL;

/* Generated via "openssl dhparam -2 -noout -C 512 2>/dev/null" */
static unsigned char dh512_p[] = {
  0xE4,0x3F,0x75,0x82,0xAD,0x0B,0x28,0xC7,0xEF,0xCE,0xBC,0x3B,
  0x14,0xBB,0xA6,0xF4,0xA2,0xE9,0xA6,0x59,0xCF,0x97,0x1C,0x86,
  0x43,0x3B,0x92,0x4A,0x6B,0x15,0x4B,0x0C,0xAC,0x8F,0xFA,0x43,
  0xE2,0xA8,0xC3,0x3B,0x7B,0x51,0x1B,0x46,0x21,0xBF,0x8C,0x06,
  0x6C,0xB1,0x49,0x75,0xC7,0xAC,0x47,0x1D,0x9D,0x64,0xD5,0x99,
  0x33,0x86,0xAD,0xEB,
};

/* Generated via "openssl dhparam -2 -noout -C 2048 2>/dev/null" */
static unsigned char dh2048_p[] = {
  0x9B,0xF4,0xC5,0x57,0x81,0x8F,0xCF,0x31,0x78,0x95,0x04,0xCD,
  0xEA,0xCC,0x30,0xEA,0xF7,0xCA,0x76,0xC8,0x8F,0x91,0xEA,0x0E,
  0x44,0x8D,0xE2,0x63,0x19,0x3B,0x4D,0x04,0xC8,0x7D,0x0D,0xFF,
  0x3D,0x52,0x76,0x02,0xF3,0xCA,0x1C,0x44,0xAF,0x0E,0xA9,0x59,
  0x02,0x40,0x75,0xD6,0xED,0x35,0x4D,0x11,0x5B,0x2B,0x73,0x23,
  0xE5,0x53,0x0B,0x1F,0xB0,0x47,0xC4,0x7F,0x95,0x5D,0xB0,0xD5,
  0xF3,0xD3,0xAB,0x5F,0x28,0x2B,0xEC,0x2C,0x15,0x0B,0x1B,0x0C,
  0xD4,0xBE,0x24,0x2F,0xC5,0x07,0x3C,0xE4,0xC5,0xE6,0x16,0x42,
  0x4C,0x31,0x04,0xBB,0x80,0x96,0xFF,0x64,0x50,0xA4,0xA5,0xB5,
  0xF5,0x3A,0xBA,0x57,0xE4,0xE6,0xC2,0x23,0x0A,0xB6,0x27,0xC4,
  0x06,0x01,0x1E,0x98,0x20,0x09,0xC8,0xB7,0x90,0x09,0x86,0x06,
  0xAA,0x85,0xE7,0x02,0xC8,0xC6,0xD9,0x1D,0xAB,0x17,0xEE,0x78,
  0x73,0x78,0x88,0x7F,0xA7,0xF2,0x34,0xA7,0xDD,0x02,0x16,0x36,
  0x0D,0x77,0x16,0x3E,0x95,0xAE,0x02,0xEE,0x36,0x37,0xD5,0x61,
  0x5D,0xFE,0xC6,0x0B,0xDF,0xCE,0xB9,0x26,0x31,0x6F,0x34,0x92,
  0xBB,0xBB,0x91,0x29,0x77,0x62,0x1D,0x75,0xA0,0x51,0x8D,0x31,
  0x4C,0x64,0x4E,0xBF,0xDC,0xE8,0x67,0x17,0x90,0x6A,0x80,0xE9,
  0xD7,0xD8,0x56,0x4E,0x85,0x21,0x9C,0xFB,0xE6,0x1B,0xD8,0x05,
  0xFD,0x13,0x77,0x00,0x96,0x2D,0x0C,0x2A,0x95,0x1A,0x08,0x82,
  0x2E,0xB3,0xE2,0xFC,0xE8,0xA6,0xF1,0x16,0x37,0x57,0x82,0xD6,
  0xF5,0xAB,0xA9,0x43,0x8F,0x33,0xB0,0x57,0x38,0x6E,0x61,0xD4,
  0xDD,0xE0,0x1C,0xCB,
};

static ssl_option_t ssl_options[] = {
  /* OpenSSL 0.9.7 and 0.9.8 */
  {"all",                              SSL_OP_ALL},
  {"cipher_server_preference",         SSL_OP_CIPHER_SERVER_PREFERENCE},
  {"dont_insert_empty_fragments",      SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS},
  {"ephemeral_rsa",                    SSL_OP_EPHEMERAL_RSA},
  {"netscape_ca_dn_bug",               SSL_OP_NETSCAPE_CA_DN_BUG},
  {"netscape_challenge_bug",           SSL_OP_NETSCAPE_CHALLENGE_BUG},
  {"microsoft_big_sslv3_buffer",       SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER},
  {"microsoft_sess_id_bug",            SSL_OP_MICROSOFT_SESS_ID_BUG},
  {"msie_sslv2_rsa_padding",           SSL_OP_MSIE_SSLV2_RSA_PADDING},
  {"netscape_demo_cipher_change_bug",  SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG},
  {"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG},
  {"no_session_resumption_on_renegotiation", 
      SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION},
  {"no_sslv2",                         SSL_OP_NO_SSLv2},
  {"no_sslv3",                         SSL_OP_NO_SSLv3},
  {"no_tlsv1",                         SSL_OP_NO_TLSv1},
  {"pkcs1_check_1",                    SSL_OP_PKCS1_CHECK_1},
  {"pkcs1_check_2",                    SSL_OP_PKCS1_CHECK_2},
  {"single_dh_use",                    SSL_OP_SINGLE_DH_USE},
  {"ssleay_080_client_dh_bug",         SSL_OP_SSLEAY_080_CLIENT_DH_BUG},
  {"sslref2_reuse_cert_type_bug",      SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG},
  {"tls_block_padding_bug",            SSL_OP_TLS_BLOCK_PADDING_BUG},
  {"tls_d5_bug",                       SSL_OP_TLS_D5_BUG},
  {"tls_rollback_bug",                 SSL_OP_TLS_ROLLBACK_BUG},
  /* OpenSSL 0.9.8 only */
#if OPENSSL_VERSION_NUMBER > 0x00908000L
  {"cookie_exchange",                  SSL_OP_COOKIE_EXCHANGE},
  {"no_query_mtu",                     SSL_OP_NO_QUERY_MTU},
  {"single_ecdh_use",                  SSL_OP_SINGLE_ECDH_USE},
#endif
  /* OpenSSL 0.9.8f and above */
#if defined(SSL_OP_NO_TICKET)
  {"no_ticket",                        SSL_OP_NO_TICKET},
#endif
#if defined(SSL_OP_NO_COMPRESSION)
  {"no_compression",                          SSL_OP_NO_COMPRESSION},
#endif
  {NULL, 0L}
};

/*--------------------------- Auxiliary Functions ----------------------------*/

/**
 * Return the context.
 */
p_context checkctx(lua_State *L, int idx)
{
  return (p_context)luaL_checkudata(L, idx, "SSL:Context");
}

/**
 * Prepare the SSL options flag.
 */
static int set_option_flag(const char *opt, unsigned long *flag)
{
  ssl_option_t *p;
  for (p = ssl_options; p->name; p++) {
    if (!strcmp(opt, p->name)) {
      *flag |= p->code;
      return 1;
    }
  }
  return 0;
}

/**
 * Find the protocol.
 */
static SSL_METHOD* str2method(const char *method)
{
  if (!strcmp(method, "sslv3"))  return SSLv3_method();
  if (!strcmp(method, "tlsv1"))  return TLSv1_method();
  if (!strcmp(method, "sslv23")) return SSLv23_method();
  return NULL;
}

/**
 * Prepare the SSL handshake verify flag.
 */
static int set_verify_flag(const char *str, int *flag)
{
  if (!strcmp(str, "none")) { 
    *flag |= SSL_VERIFY_NONE;
    return 1;
  }
  if (!strcmp(str, "peer")) {
    *flag |= SSL_VERIFY_PEER;
    return 1;
  }
  if (!strcmp(str, "client_once")) {
    *flag |= SSL_VERIFY_CLIENT_ONCE;
    return 1;
  }
  if (!strcmp(str, "fail_if_no_peer_cert")) { 
    *flag |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
    return 1;
  }
  return 0;
}

/**
 * Password callback for reading the private key.
 */
static int passwd_cb(char *buf, int size, int flag, void *udata)
{
  lua_State *L = (lua_State*)udata;
  switch (lua_type(L, 3)) {
  case LUA_TFUNCTION:
    lua_pushvalue(L, 3);
    lua_call(L, 0, 1);
    if (lua_type(L, -1) != LUA_TSTRING)
       return 0;
    /* fallback */
  case LUA_TSTRING:
    strncpy(buf, lua_tostring(L, -1), size);
    buf[size-1] = '\0';
    return (int)strlen(buf);
  }
  return 0;
}

static DH *get_dh(const unsigned char *p, int len)
{
  DH *dh = NULL;
  static unsigned char g[] = { 0x02 };

  if ((dh = DH_new()) == NULL) return NULL;
  dh->p = BN_bin2bn(p, len, NULL);
  dh->g = BN_bin2bn(g, sizeof(g), NULL);
  if (dh->p == NULL || dh->g == NULL) {
    DH_free(dh);
    return NULL;
  }

  return dh;
}

/**
 * DH parameter callback
 */
static DH *dh_param_cb(SSL *ssl, int is_export, int keylength)
{
  /* Logic in postfix and dovecot, but we're using a 2048-bit group... */
  if (is_export && keylength == 512) {
    if (dh_512 == NULL) { dh_512 = get_dh(dh512_p, sizeof(dh512_p)); }
    return dh_512;
  } else {
    if (dh_larger == NULL) { dh_larger = get_dh(dh2048_p, sizeof(dh2048_p)); }
    return dh_larger;
  }
}


/*------------------------------ Lua Functions -------------------------------*/

/**
 * Create a SSL context.
 */
static int create(lua_State *L)
{
  p_context ctx;
  SSL_METHOD *method;

  if (luasec_sslctx_idx == -1) {
    luasec_sslctx_idx = SSL_CTX_get_ex_new_index(0, "luasec sslctx context", NULL, NULL, NULL);
    if (luasec_sslctx_idx == -1) {
      lua_pushnil(L);
      lua_pushstring(L, "error creating luasec SSL index");
      return 2;
    }
  }
  method = str2method(luaL_checkstring(L, 1));
  if (!method) {
    lua_pushnil(L);
    lua_pushstring(L, "invalid protocol");
    return 2;
  }
  ctx = (p_context) lua_newuserdata(L, sizeof(t_context));
  if (!ctx) {
    lua_pushnil(L);
    lua_pushstring(L, "error creating context");
    return 2;
  }  
  ctx->context = SSL_CTX_new(method);
  if (!ctx->context) {
    lua_pushnil(L);
    lua_pushstring(L, "error creating context");
    return 2;
  }
  ctx->verify_flags = LUASEC_VERIFY_FLAGS_NONE;
  ctx->mode = MD_CTX_INVALID;
  /* No session support */
  SSL_CTX_set_session_cache_mode(ctx->context, SSL_SESS_CACHE_OFF);
  /*
   * Support ephemeral diffie-hellman key exchange.  This is only needed
   * for server mode, but clearer to put it here rather than set_mode.
   */
  SSL_CTX_set_tmp_dh_callback(ctx->context, dh_param_cb);
  SSL_CTX_set_ex_data(ctx->context, luasec_sslctx_idx, ctx);

  luaL_getmetatable(L, "SSL:Context");
  lua_setmetatable(L, -2);
  return 1;
}

/**
 * Load the trusting certificates.
 */
static int load_locations(lua_State *L)
{
  SSL_CTX *ctx = ctx_getcontext(L, 1);
  const char *cafile = luaL_optstring(L, 2, NULL);
  const char *capath = luaL_optstring(L, 3, NULL);
  if (SSL_CTX_load_verify_locations(ctx, cafile, capath) != 1) {
    lua_pushboolean(L, 0);
    lua_pushfstring(L, "error loading CA locations (%s)",
      ERR_reason_error_string(ERR_get_error()));
    return 2;
  }
  lua_pushboolean(L, 1);
  return 1;
}

/**
 * Load the certificate file.
 */
static int load_cert(lua_State *L)
{
  SSL_CTX *ctx = ctx_getcontext(L, 1);
  const char *filename = luaL_checkstring(L, 2);
  if (SSL_CTX_use_certificate_chain_file(ctx, filename) != 1) {
    lua_pushboolean(L, 0);
    lua_pushfstring(L, "error loading certificate (%s)",
      ERR_reason_error_string(ERR_get_error()));
    return 2;
  }
  lua_pushboolean(L, 1);
  return 1;
}

/**
 * Load the key file -- only in PEM format.
 */
static int load_key(lua_State *L)
{
  int ret = 1;
  SSL_CTX *ctx = ctx_getcontext(L, 1);
  const char *filename = luaL_checkstring(L, 2);
  switch (lua_type(L, 3)) {
  case LUA_TSTRING:
  case LUA_TFUNCTION:
    SSL_CTX_set_default_passwd_cb(ctx, passwd_cb);
    SSL_CTX_set_default_passwd_cb_userdata(ctx, L);
    /* fallback */
  case LUA_TNIL: 
    if (SSL_CTX_use_PrivateKey_file(ctx, filename, SSL_FILETYPE_PEM) == 1)
      lua_pushboolean(L, 1);
    else {
      ret = 2;
      lua_pushboolean(L, 0);
      lua_pushfstring(L, "error loading private key (%s)",
        ERR_reason_error_string(ERR_get_error()));
    }
    SSL_CTX_set_default_passwd_cb(ctx, NULL);
    SSL_CTX_set_default_passwd_cb_userdata(ctx, NULL);
    break;
  default:
    lua_pushstring(L, "invalid callback value");
    lua_error(L);
  }
  return ret;
}

/**
 * Load a DH params files.  This is a global LuaSec thing.
 */
static int load_dhparams(lua_State *L)
{
  const char *filename = luaL_checkstring(L, 1);
  FILE *paramfile;
  DH *dh;

  paramfile = fopen(filename, "r");
  if (!paramfile) {
    lua_pushboolean(L, 0);
    lua_pushfstring(L, "error reading dh param file %s: %s", filename,
      strerror(errno));
    return 2;
  }

  dh = PEM_read_DHparams(paramfile, NULL, NULL, NULL);
  fclose(paramfile);
  if (!dh) {
    lua_pushboolean(L, 0);
    lua_pushfstring(L, "error loading dh param file %s: %s", filename,
      ERR_reason_error_string(ERR_get_error()));
    return 2;
  }

  if (dh_larger)
    DH_free(dh_larger);

  dh_larger = dh;

  lua_pushboolean(L, 1);
  return 1;
}

/**
 * Set the cipher list.
 */
static int set_cipher(lua_State *L)
{
  SSL_CTX *ctx = ctx_getcontext(L, 1);
  const char *list = luaL_checkstring(L, 2);
  if (SSL_CTX_set_cipher_list(ctx, list) != 1) {
    lua_pushboolean(L, 0);
    lua_pushfstring(L, "error setting cipher list (%s)",
      ERR_reason_error_string(ERR_get_error()));
    return 2;
  }
  lua_pushboolean(L, 1);
  return 1;
}

/**
 * Set the depth for certificate checking.
 */
static int set_depth(lua_State *L)
{
  SSL_CTX *ctx = ctx_getcontext(L, 1);
  SSL_CTX_set_verify_depth(ctx, luaL_checkint(L, 2));
  lua_pushboolean(L, 1);
  return 1;
}

int verify_cb(int preverify_ok, X509_STORE_CTX *x509_ctx)
{
  SSL_CTX *context;
  SSL *ssl;
  p_context l_ctx;

  /* Short-circuit optimization */
  if (preverify_ok)
    return 1;

  ssl = X509_STORE_CTX_get_ex_data(x509_ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
  context = ssl->ctx;
  l_ctx = SSL_CTX_get_ex_data(context, luasec_sslctx_idx);

  if (l_ctx->verify_flags & LUASEC_VERIFY_FLAGS_IGNORE_PURPOSE) {
    int err, depth;

    err = X509_STORE_CTX_get_error(x509_ctx);
    depth = X509_STORE_CTX_get_error_depth(x509_ctx);

    if (depth == 0 && err == X509_V_ERR_INVALID_PURPOSE) {
      /* You see nothing! */
      X509_STORE_CTX_set_error(x509_ctx, X509_V_OK);
      preverify_ok = 1;
    }
  }
  return (l_ctx->verify_flags & LUASEC_VERIFY_FLAGS_ALWAYS_CONTINUE ? 1 : preverify_ok);
}

/**
 * Set the handshake verify options.
 */
static int set_verify(lua_State *L)
{
  int i;
  int flag = 0, vflag = 0;
  int ignore_errors = 0;
  p_context ctx = checkctx(L, 1);
  int max = lua_gettop(L);
  /* any flag? */
  if (max > 1) {
    ctx->verify_flags = LUASEC_VERIFY_FLAGS_NONE;
    for (i = 2; i <= max; i++) {
      const char *s = luaL_checkstring(L, i);
      if (!strcmp(s, "continue")) {
        ctx->verify_flags |= LUASEC_VERIFY_FLAGS_ALWAYS_CONTINUE;
        ignore_errors = 1;
      } else if (!strcmp(s, "ignore_purpose")) {
        ctx->verify_flags |= LUASEC_VERIFY_FLAGS_IGNORE_PURPOSE;
      } else if (!strcmp(s, "crl_check")) {
        vflag |= X509_V_FLAG_CRL_CHECK;
      } else if (!strcmp(s, "crl_check_chain")) {
        vflag |= X509_V_FLAG_CRL_CHECK_ALL;
      } else if (!set_verify_flag(s, &flag)) {
        lua_pushboolean(L, 0);
        lua_pushstring(L, "invalid verify option");
        return 2;
      }
    }
    SSL_CTX_set_verify(ctx->context, flag, ctx->verify_flags ? verify_cb : NULL);
    if(vflag)
    {
      X509_STORE *store = SSL_CTX_get_cert_store(ctx->context);
      X509_STORE_set_flags(store, vflag);
    }
  }
  lua_pushboolean(L, 1);
  return 1;
}

/**
 * Set the protocol options.
 */
static int set_options(lua_State *L)
{
  int i;
  unsigned long flag = 0L;
  SSL_CTX *ctx = ctx_getcontext(L, 1);
  int max = lua_gettop(L);
  /* any option? */
  if (max > 1) {
    for (i = 2; i <= max; i++) {
      if (!set_option_flag(luaL_checkstring(L, i), &flag)) {
        lua_pushboolean(L, 0);
        lua_pushstring(L, "invalid option");
        return 2;
      }
    }
    SSL_CTX_set_options(ctx, flag);
  }
  lua_pushboolean(L, 1);
  return 1;
}

/**
 * Set the context mode.
 */
static int set_mode(lua_State *L)
{
  p_context ctx = checkctx(L, 1);
  const char *str = luaL_checkstring(L, 2);
  if (!strcmp("server", str)) {
    ctx->mode = MD_CTX_SERVER;
    lua_pushboolean(L, 1);
    return 1;
  }
  if(!strcmp("client", str)) {
    ctx->mode = MD_CTX_CLIENT;
    lua_pushboolean(L, 1);
    return 1;
  }
  lua_pushboolean(L, 0);
  lua_pushstring(L, "invalid mode");
  return 1;
}   

/**
 * Return a pointer to SSL_CTX structure.
 */
static int raw_ctx(lua_State *L)
{
  p_context ctx = checkctx(L, 1);
  lua_pushlightuserdata(L, (void*)ctx->context);
  return 1;
}

/**
 * Package functions
 */
static luaL_Reg funcs[] = {
  {"create",     create},
  {"locations",  load_locations},
  {"loadcert",   load_cert},
  {"loadkey",    load_key},
  {"setcipher",  set_cipher},
  {"setdepth",   set_depth},
  {"setverify",  set_verify},
  {"setoptions", set_options},
  {"setmode",    set_mode},
  {"rawcontext", raw_ctx},
  {"loaddhparams", load_dhparams},
  {NULL, NULL}
};

/*-------------------------------- Metamethods -------------------------------*/

/**
 * Collect SSL context -- GC metamethod.
 */
static int meth_destroy(lua_State *L)
{
  p_context ctx = checkctx(L, 1);
  if (ctx->context) {
    SSL_CTX_free(ctx->context);
    ctx->context = NULL;
  }
  return 0;
}

/**
 * Object information -- tostring metamethod.
 */
static int meth_tostring(lua_State *L)
{
  p_context ctx = checkctx(L, 1);
  lua_pushfstring(L, "SSL context: %p", ctx);
  return 1;
}

/**
 * Context metamethods.
 */
static luaL_Reg meta[] = {
  {"__gc",       meth_destroy},
  {"__tostring", meth_tostring},
  {NULL, NULL}
};


/*----------------------------- Public Functions  ---------------------------*/

/**
 * Retrieve the SSL context from the Lua stack.
 */
SSL_CTX* ctx_getcontext(lua_State *L, int idx)
{
  p_context ctx = checkctx(L, idx);
  return ctx->context;
}

/**
 * Retrieve the mode from the context in the Lua stack.
 */
char ctx_getmode(lua_State *L, int idx)
{
  p_context ctx = checkctx(L, idx);
  return ctx->mode;
}

/*------------------------------ Initialization ------------------------------*/

/**
 * Registre the module.
 */
int luaopen_ssl_context(lua_State *L)
{
  luaL_newmetatable(L, "SSL:Context");
  luaL_register(L, NULL, meta);
  luaL_register(L, "ssl.context", funcs);
  return 1;
}