/***************************************************************************
* nse_ssl_cert.cc -- NSE userdatum representing an SSL certificate. *
* *
***********************IMPORTANT NMAP LICENSE TERMS************************
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***************************************************************************/
/* $Id:$ */
#include "nbase.h"
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <string.h>
#include <openssl/bio.h>
#include <openssl/pem.h>
#include <openssl/ssl.h>
#include <openssl/x509.h>
extern "C"
{
#include "lua.h"
#include "lauxlib.h"
}
#include "nse_nsock.h"
struct cert_userdata {
X509 *cert;
int attributes_table;
};
SSL *nse_nsock_get_ssl(lua_State *L);
/* This is a reference to a table that will be used as the metatable for
certificate attribute tables. It has an __index entry that points to the
global table of certificate functions like digest. */
static int ssl_cert_methods_index_ref = LUA_NOREF;
/* Calculate the digest of the certificate using the given algorithm. */
static int ssl_cert_digest(lua_State *L)
{
struct cert_userdata *udata;
const char *algorithm;
unsigned char buf[256];
unsigned int n;
const EVP_MD *md;
udata = (struct cert_userdata *) luaL_checkudata(L, 1, "SSL_CERT");
algorithm = luaL_checkstring(L, 2);
md = EVP_get_digestbyname(algorithm);
if (md == NULL)
return 0;
n = sizeof(buf);
if (X509_digest(udata->cert, md, buf, &n) != 1)
return 0;
lua_pushlstring(L, (char *) buf, n);
return 1;
}
/* These are the contents of the table that is pointed to by the table that has
ssl_cert_methods_index_ref as a reference. */
static struct luaL_reg ssl_cert_methods[] = {
{ "digest", ssl_cert_digest },
{ NULL, NULL },
};
/* This is a helper function for x509_name_to_table. It takes the ASN1_OBJECT
passed as an argument, turns it into a table key, and pushes it on the stack.
The key is a string (like "commonName") if the object has an NID known by
OBJ_obj2nid; otherwise it is an array containing the OID components as
strings: { "2", "5", "4", "3" }. */
static void obj_to_key(lua_State *L, const ASN1_OBJECT *obj)
{
int nid;
nid = OBJ_obj2nid(obj);
if (nid == NID_undef) {
size_t size = 1;
char *buf = (char *) lua_newuserdata(L, size);
const char *p, *q;
int i, n;
while ((n = OBJ_obj2txt(buf, size, obj, 1)) < 0 || (unsigned) n >= size) {
size = size * 2;
buf = (char *) lua_newuserdata(L, size);
memcpy(lua_touserdata(L, -1), lua_touserdata(L, -2), lua_objlen(L, -2));
lua_replace(L, -2);
}
lua_newtable(L);
i = 1;
p = buf;
q = p;
while (*q != '\0') {
q = strchr(p, '.');
if (q == NULL)
q = strchr(p, '\0');
lua_pushlstring(L, p, q - p);
lua_rawseti(L, -2, i++);
p = q + 1;
}
lua_replace(L, -2); /* replace userdata with table */
} else {
lua_pushstring(L, OBJ_nid2ln(nid));
}
}
/* This is a helper function for l_get_ssl_certificate. It builds a table from
the given X509_NAME, using keys returned from obj_to_key as keys. The result
is pushed on the stack. */
static void x509_name_to_table(lua_State *L, X509_NAME *name)
{
int i;
lua_newtable(L);
for (i = 0; i < X509_NAME_entry_count(name); i++) {
X509_NAME_ENTRY *entry;
const ASN1_OBJECT *obj;
const ASN1_STRING *value;
entry = X509_NAME_get_entry(name, i);
obj = X509_NAME_ENTRY_get_object(entry);
value = X509_NAME_ENTRY_get_data(entry);
obj_to_key(L, obj);
lua_pushlstring(L, (const char *) value->data, value->length);
lua_settable(L, -3);
}
}
/* Parse as a decimal integer the len characters starting at s. This function
can only process positive numbers; if the return value is negative then a
parsing error occurred. */
static int parse_int(const unsigned char *s, size_t len)
{
char buf[32];
char *tail;
long v;
if (len == 0)
return -1;
if (!isdigit((int) (unsigned char) s[0]))
return -1;
if (len > sizeof(buf) - 1)
return -1;
memcpy(buf, s, len);
buf[len] = '\0';
errno = 0;
v = strtol(buf, &tail, 10);
if (errno != 0 || *tail != '\0')
return -1;
if ((int) v != v || v < 0)
return -1;
return (int) v;
}
/* This is a helper function for asn1_time_to_obj. It parses a textual ASN1_TIME
value and stores the time in the given struct tm. It returns 0 on success and
-1 on a parse error. */
static int time_to_tm(const ASN1_TIME *t, struct tm *result)
{
const unsigned char *p;
p = t->data;
if (t->length == 13 && t->data[t->length - 1] == 'Z') {
/* yymmddhhmmssZ */
int year;
year = parse_int(t->data, 2);
if (year < 0)
return -1;
/* "In coming up with the worlds least efficient machine-readable time
encoding format, the ISO nevertheless decided to forgo the encoding of
centuries, a problem which has been kludged around by redefining the time
as UTCTime if the date is 2049 or ealier, and GeneralizedTime if the date
is 2050 or later."
http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt */
if (year < 50)
result->tm_year = 2000 + year;
else
result->tm_year = 1900 + year;
p = t->data + 2;
} else if (t->length == 14) {
/* yyyymmddhhmmss */
result->tm_year = parse_int(t->data, 4);
if (result->tm_year < 0)
return -1;
p = t->data + 4;
} else {
return -1;
}
result->tm_mon = parse_int(p, 2);
/* struct tm uses zero-indexed months. */
if (result->tm_mon == 0)
return -1;
result->tm_mon--;
result->tm_mday = parse_int(p + 2, 2);
result->tm_hour = parse_int(p + 4, 2);
result->tm_min = parse_int(p + 6, 2);
result->tm_sec = parse_int(p + 8, 2);
if (result->tm_mon < 0 || result->tm_mday < 0 || result->tm_hour < 0
|| result->tm_min < 0 || result->tm_sec < 0) {
return -1;
}
return 0;
}
/* This is a helper function for asn1_time_to_obj. It converts a struct tm into
a date table as returned by the Lua date os.date("!*t"), with the exception
that the wday and yday fields are not present. */
static void tm_to_table(lua_State *L, const struct tm *tm)
{
lua_newtable(L);
lua_pushnumber(L, tm->tm_year);
lua_setfield(L, -2, "year");
/* Lua uses one-indexed months. */
lua_pushnumber(L, tm->tm_mon + 1);
lua_setfield(L, -2, "month");
lua_pushnumber(L, tm->tm_mday);
lua_setfield(L, -2, "day");
lua_pushnumber(L, tm->tm_hour);
lua_setfield(L, -2, "hour");
lua_pushnumber(L, tm->tm_min);
lua_setfield(L, -2, "min");
lua_pushnumber(L, tm->tm_sec);
lua_setfield(L, -2, "sec");
/* Omit tm_wday and tm_yday. */
}
/* This is a helper function for x509_validity_to_table. It takes teh given
ASN1_TIME and covnerts it to a value on the stack, which is one of
nil, if the time is NULL;
a date table, if the date can be parsed; and
a string of the raw bytes, if the date cannot be parsed. */
static void asn1_time_to_obj(lua_State *L, const ASN1_TIME *s)
{
struct tm tm;
if (s == NULL) {
lua_pushnil(L);
} else if (time_to_tm(s, &tm) == 0) {
tm_to_table(L, &tm);
} else {
lua_pushlstring(L, (const char *) s->data, s->length);
}
}
/* This is a helper functino for x509_validity_to_table. It builds a table with
the two members "notBefore" and "notAfter", whose values are what is returned
from asn1_time_to_obj. */
static void x509_validity_to_table(lua_State *L, const X509 *cert)
{
lua_newtable(L);
asn1_time_to_obj(L, X509_get_notBefore(cert));
lua_setfield(L, -2, "notBefore");
asn1_time_to_obj(L, X509_get_notAfter(cert));
lua_setfield(L, -2, "notAfter");
}
/* This is a helper function for l_get_ssl_certificate. It converts the
certificate into a PEM-encoded string on the stack. */
static void cert_pem_to_string(lua_State *L, X509 *cert)
{
BIO *bio;
char *buf;
long size;
bio = BIO_new(BIO_s_mem());
assert(bio != NULL);
assert(PEM_write_bio_X509(bio, cert));
size = BIO_get_mem_data(bio, &buf);
lua_pushlstring(L, buf, size);
BIO_vfree(bio);
}
/* This is a helper function for l_get_ssl_certificate. It converts the
public-key type to a string. */
static const char *pkey_type_to_string(int type)
{
switch (type) {
case EVP_PKEY_RSA:
return "rsa";
case EVP_PKEY_DSA:
return "dsa";
case EVP_PKEY_DH:
return "dh";
#ifdef EVP_PKEY_EC
case EVP_PKEY_EC:
return "ec";
#endif
default:
return "unknown";
}
}
int l_get_ssl_certificate(lua_State *L)
{
SSL *ssl;
struct cert_userdata *udata;
X509 *cert;
X509_NAME *subject, *issuer;
EVP_PKEY *pubkey;
ssl = nse_nsock_get_ssl(L);
cert = SSL_get_peer_certificate(ssl);
if (cert == NULL) {
lua_pushnil(L);
return 1;
}
udata = (struct cert_userdata *) lua_newuserdata(L, sizeof(*udata));
udata->cert = cert;
lua_newtable(L);
subject = X509_get_subject_name(cert);
if (subject != NULL) {
x509_name_to_table(L, subject);
lua_setfield(L, -2, "subject");
}
issuer = X509_get_issuer_name(cert);
if (issuer != NULL) {
x509_name_to_table(L, issuer);
lua_setfield(L, -2, "issuer");
}
x509_validity_to_table(L, cert);
lua_setfield(L, -2, "validity");
cert_pem_to_string(L, cert);
lua_setfield(L, -2, "pem");
pubkey = X509_get_pubkey(cert);
lua_newtable(L);
lua_pushstring(L, pkey_type_to_string(pubkey->type));
lua_setfield(L, -2, "type");
lua_pushnumber(L, EVP_PKEY_bits(pubkey));
lua_setfield(L, -2, "bits");
lua_setfield(L, -2, "pubkey");
EVP_PKEY_free(pubkey);
/* At this point the certificate-specific table of attributes is at the top of
the stack. We give it a metatable with an __index entry that points into
the global shared table of certificate functions. */
lua_rawgeti(L, LUA_REGISTRYINDEX, ssl_cert_methods_index_ref);
lua_setmetatable(L, -2);
udata->attributes_table = luaL_ref(L, LUA_REGISTRYINDEX);
luaL_getmetatable(L, "SSL_CERT");
lua_setmetatable(L, -2);
return 1;
}
static int l_ssl_cert_index(lua_State *L)
{
struct cert_userdata *udata;
udata = (struct cert_userdata *) luaL_checkudata(L, 1, "SSL_CERT");
lua_rawgeti(L, LUA_REGISTRYINDEX, udata->attributes_table);
/* The key. */
lua_pushvalue(L, 2);
/* Look it up in the table of attributes. */
lua_gettable(L, -2);
return 1;
}
static int l_ssl_cert_gc(lua_State *L)
{
struct cert_userdata *udata;
udata = (struct cert_userdata *) luaL_checkudata(L, 1, "SSL_CERT");
X509_free(udata->cert);
luaL_unref(L, LUA_REGISTRYINDEX, udata->attributes_table);
return 0;
}
void nse_nsock_init_ssl_cert(lua_State *L)
{
luaL_newmetatable(L, "SSL_CERT");
lua_pushcclosure(L, l_ssl_cert_index, 0);
lua_setfield(L, -2, "__index");
lua_pushcclosure(L, l_ssl_cert_gc, 0);
lua_setfield(L, -2, "__gc");
/* Create a table with an __index entry that will be used as a metatable for
per-certificate attribute tables. This gives the tables access to the
global shared table of certificate functions. */
lua_newtable(L);
lua_newtable(L);
luaL_register(L, NULL, ssl_cert_methods);
lua_setfield(L, -2, "__index");
ssl_cert_methods_index_ref = luaL_ref(L, LUA_REGISTRYINDEX);
}