/*
* Match a string against a list of patterns/regexes.
*
* Copyright (C) 2007-2008 Sourcefire, Inc.
*
* Authors: Török Edvin
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#ifdef CL_THREAD_SAFE
#ifndef _REENTRANT
#define _REENTRANT
#endif
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <zlib.h>
#include <limits.h>
#include <sys/types.h>
#include <assert.h>
#include "regex/regex.h"
#include "clamav.h"
#include "others.h"
#include "regex_list.h"
#include "matcher-ac.h"
#include "matcher.h"
#include "str.h"
#include "readdb.h"
#include "jsparse/textbuf.h"
#include "regex_suffix.h"
#include "default.h"
#include "hashtab.h"
#include "mpool.h"
/* Prototypes */
static regex_t *new_preg(struct regex_matcher *matcher);
static size_t reverse_string(char *pattern);
static int add_pattern_suffix(void *cbdata, const char *suffix, size_t suffix_len, const struct regex_list *regex);
static int add_static_pattern(struct regex_matcher *matcher, char* pattern);
/* ---------- */
#define MATCH_SUCCESS 0
#define MATCH_FAILED -1
/*
* Call this function when an unrecoverable error has occured, (instead of exit).
*/
static void fatal_error(struct regex_matcher* matcher)
{
regex_list_done(matcher);
matcher->list_inited = -1;/* the phishing module will know we tried to load a whitelist, and failed, so it will disable itself too*/
}
static inline size_t get_char_at_pos_with_skip(const struct pre_fixup_info* info, const char* buffer, size_t pos)
{
const char* str;
size_t realpos = 0;
if(!info) {
return (pos <= strlen(buffer)) ? buffer[pos>0 ? pos-1:0] : '\0';
}
str = info->pre_displayLink.data;
cli_dbgmsg("calc_pos_with_skip: skip:%lu, %lu - %lu \"%s\",\"%s\"\n", pos, info->host_start, info->host_end, str, buffer);
pos += info->host_start;
while(str[realpos] && !isalnum(str[realpos])) realpos++;
for(; str[realpos] && (pos>0); pos--) {
while(str[realpos]==' ') realpos++;
realpos++;
}
while(str[realpos]==' ') realpos++;
cli_dbgmsg("calc_pos_with_skip:%s\n",str+realpos);
return (pos>0 && !str[realpos]) ? '\0' : str[realpos>0?realpos-1:0];
}
static int validate_subdomain(const struct regex_list *regex, const struct pre_fixup_info *pre_fixup, const char *buffer, size_t buffer_len, char *real_url, size_t real_len, char *orig_real_url)
{
char c;
size_t match_len;
if(!regex || !regex->pattern)
return 0;
match_len = strlen(regex->pattern);
if(((c=get_char_at_pos_with_skip(pre_fixup,buffer,buffer_len+1))==' ' || c=='\0' || c=='/' || c=='?') &&
(match_len == buffer_len || /* full match */
(match_len < buffer_len &&
((c=get_char_at_pos_with_skip(pre_fixup,buffer,buffer_len-match_len))=='.' || (c==' ')) )
/* subdomain matched*/)) {
/* we have an extra / at the end */
if(match_len > 0) match_len--;
cli_dbgmsg("Got a match: %s with %s\n", buffer, regex->pattern);
cli_dbgmsg("Before inserting .: %s\n", orig_real_url);
if(real_len >= match_len + 1) {
const size_t pos = real_len - match_len - 1;
if(real_url[pos] != '.') {
/* we need to shift left, and insert a '.'
* we have an extra '.' at the beginning inserted by get_host to have room,
* orig_real_url has to be used here,
* because we want to overwrite that extra '.' */
size_t orig_real_len = strlen(orig_real_url);
cli_dbgmsg("No dot here:%s\n",real_url+pos);
real_url = orig_real_url;
memmove(real_url, real_url+1, orig_real_len-match_len-1);
real_url[orig_real_len-match_len-1]='.';
cli_dbgmsg("After inserting .: %s\n", real_url);
}
}
return 1;
}
cli_dbgmsg("Ignoring false match: %s with %s, mismatched character: %c\n", buffer, regex->pattern, c);
return 0;
}
/*
* @matcher - matcher structure to use
* @real_url - href target
* @display_url - <a> tag contents
* @hostOnly - if you want to match only the host part
* @is_whitelist - is this a lookup in whitelist?
*
* @return - CL_SUCCESS - url doesn't match
* - CL_VIRUS - url matches list
*
* Do not send NULL pointers to this function!!
*
*/
int regex_list_match(struct regex_matcher* matcher,char* real_url,const char* display_url,const struct pre_fixup_info* pre_fixup,int hostOnly,const char **info, int is_whitelist)
{
char* orig_real_url = real_url;
struct regex_list *regex;
size_t real_len, display_len, buffer_len;
assert(matcher);
assert(real_url);
assert(display_url);
*info = NULL;
if(!matcher->list_inited)
return 0;
assert(matcher->list_built);
/* skip initial '.' inserted by get_host */
if(real_url[0] == '.') real_url++;
if(display_url[0] == '.') display_url++;
real_len = strlen(real_url);
display_len = strlen(display_url);
buffer_len = (hostOnly && !is_whitelist) ? real_len + 1 : real_len + display_len + 1 + 1;
if(buffer_len < 3) {
/* too short, no match possible */
return 0;
}
{
char *buffer = cli_malloc(buffer_len+1);
char *bufrev;
int rc = 0, root;
struct cli_ac_data mdata;
struct cli_ac_result *res = NULL;
if(!buffer)
return CL_EMEM;
strncpy(buffer,real_url,real_len);
buffer[real_len]= (!is_whitelist && hostOnly) ? '/' : ':';
if(!hostOnly || is_whitelist) {
strncpy(buffer+real_len+1,display_url,display_len);
}
buffer[buffer_len - 1] = '/';
buffer[buffer_len]=0;
cli_dbgmsg("Looking up in regex_list: %s\n", buffer);
if((rc = cli_ac_initdata(&mdata, 0, 0, 0, CLI_DEFAULT_AC_TRACKLEN)))
return rc;
bufrev = cli_strdup(buffer);
if(!bufrev)
return CL_EMEM;
reverse_string(bufrev);
rc = filter_search(&matcher->filter, (const unsigned char*)bufrev, buffer_len) != -1;
if(rc == -1) {
free(buffer);
free(bufrev);
/* filter says this suffix doesn't match.
* The filter has false positives, but no false
* negatives */
return 0;
}
rc = cli_ac_scanbuff((const unsigned char*)bufrev,buffer_len, NULL, (void*)®ex, &res, &matcher->suffixes,&mdata,0,0,NULL,AC_SCAN_VIR,NULL);
free(bufrev);
cli_ac_freedata(&mdata);
rc = 0;
root = matcher->root_regex_idx;
while(res || root) {
struct cli_ac_result *q;
if (!res) {
regex = matcher->suffix_regexes[root].head;
root = 0;
} else {
regex = res->customdata;
}
while(!rc && regex) {
/* loop over multiple regexes corresponding to
* this suffix */
if (!regex->preg) {
/* we matched a static pattern */
rc = validate_subdomain(regex, pre_fixup, buffer, buffer_len, real_url, real_len, orig_real_url);
} else {
rc = !cli_regexec(regex->preg, buffer, 0, NULL, 0);
}
if(rc) *info = regex->pattern;
regex = regex->nxt;
}
if (res) {
q = res;
res = res->next;
free(q);
}
}
free(buffer);
if(!rc)
cli_dbgmsg("Lookup result: not in regex list\n");
else
cli_dbgmsg("Lookup result: in regex list\n");
return rc;
}
}
/* Initialization & loading */
/* Initializes @matcher, allocating necesarry substructures */
int init_regex_list(struct regex_matcher* matcher, uint8_t dconf_prefiltering)
{
#ifdef USE_MPOOL
mpool_t *mp = matcher->mempool;
#endif
int rc;
assert(matcher);
memset(matcher, 0, sizeof(*matcher));
matcher->list_inited=1;
matcher->list_built=0;
matcher->list_loaded=0;
cli_hashtab_init(&matcher->suffix_hash, 512);
#ifdef USE_MPOOL
matcher->mempool = mp;
matcher->suffixes.mempool = mp;
assert(mp && "mempool must be initialized");
#endif
if((rc = cli_ac_init(&matcher->suffixes, 2, 32, dconf_prefiltering))) {
return rc;
}
#ifdef USE_MPOOL
matcher->sha256_hashes.mempool = mp;
matcher->hostkey_prefix.mempool = mp;
#endif
if((rc = cli_bm_init(&matcher->sha256_hashes))) {
return rc;
}
if((rc = cli_bm_init(&matcher->hostkey_prefix))) {
return rc;
}
filter_init(&matcher->filter);
return CL_SUCCESS;
}
static int functionality_level_check(char* line)
{
char* ptmin;
char* ptmax;
size_t j;
ptmin = strrchr(line,':');
if(!ptmin)
return CL_SUCCESS;
ptmin++;
ptmax = strchr(ptmin,'-');
if(!ptmax)
return CL_SUCCESS;/* there is no functionality level specified, so we're ok */
else {
size_t min, max;
ptmax++;
for(j=0;j+ptmin+1 < ptmax;j++)
if(!isdigit(ptmin[j]))
return CL_SUCCESS;/* not numbers, not functionality level */
for(j=0;j<strlen(ptmax);j++)
if(!isdigit(ptmax[j]))
return CL_SUCCESS;/* see above */
ptmax[-1]='\0';
min = atoi(ptmin);
if(strlen(ptmax)==0)
max = INT_MAX;
else
max = atoi(ptmax);
if(min > cl_retflevel()) {
cli_dbgmsg("regex list line %s not loaded (required f-level: %u)\n",line,(unsigned int)min);
return CL_EMALFDB;
}
if(max < cl_retflevel())
return CL_EMALFDB;
ptmin[-1]='\0';
return CL_SUCCESS;
}
}
static int add_hash(struct regex_matcher *matcher, char* pattern, const char fl, int is_prefix)
{
int rc;
struct cli_bm_patt *pat = mpool_calloc(matcher->mempool, 1, sizeof(*pat));
struct cli_matcher *bm;
const char *vname = NULL;
if(!pat)
return CL_EMEM;
pat->pattern = (unsigned char*)cli_mpool_hex2str(matcher->mempool, pattern);
if(!pat->pattern)
return CL_EMALFDB;
pat->length = 32;
if (is_prefix) {
pat->length=4;
bm = &matcher->hostkey_prefix;
} else {
bm = &matcher->sha256_hashes;
}
if (!matcher->sha256_pfx_set.keys) {
if((rc = cli_hashset_init(&matcher->sha256_pfx_set, 1048576, 90))) {
return rc;
}
}
if (fl != 'W' && pat->length == 32 &&
cli_hashset_contains(&matcher->sha256_pfx_set, cli_readint32(pat->pattern)) &&
cli_bm_scanbuff(pat->pattern, 32, &vname, NULL, &matcher->sha256_hashes,0,NULL,NULL,NULL) == CL_VIRUS) {
if (*vname == 'W') {
/* hash is whitelisted in local.gdb */
cli_dbgmsg("Skipping hash %s\n", pattern);
mpool_free(matcher->mempool, pat->pattern);
mpool_free(matcher->mempool, pat);
return CL_SUCCESS;
}
}
pat->virname = mpool_malloc(matcher->mempool, 1);
if(!pat->virname) {
free(pat);
return CL_EMEM;
}
*pat->virname = fl;
cli_hashset_addkey(&matcher->sha256_pfx_set, cli_readint32(pat->pattern));
if((rc = cli_bm_addpatt(bm, pat, "*"))) {
cli_errmsg("add_hash: failed to add BM pattern\n");
free(pat->pattern);
free(pat->virname);
free(pat);
return CL_EMALFDB;
}
return CL_SUCCESS;
}
/* Load patterns/regexes from file */
int load_regex_matcher(struct cl_engine *engine,struct regex_matcher* matcher,FILE* fd,unsigned int *signo,unsigned int options,int is_whitelist,struct cli_dbio *dbio, uint8_t dconf_prefiltering)
{
int rc,line=0,entry=0;
char buffer[FILEBUFF];
assert(matcher);
if(matcher->list_inited==-1)
return CL_EMALFDB; /* already failed to load */
if(!fd && !dbio) {
cli_errmsg("Unable to load regex list (null file)\n");
return CL_ENULLARG;
}
cli_dbgmsg("Loading regex_list\n");
if(!matcher->list_inited) {
rc = init_regex_list(matcher, dconf_prefiltering);
if (!matcher->list_inited) {
cli_errmsg("Regex list failed to initialize!\n");
fatal_error(matcher);
return rc;
}
}
/*
* Regexlist db format (common to .wdb(whitelist) and .pdb(domainlist) files:
* Multiple lines of form, (empty lines are skipped):
* Flags RealURL DisplayedURL
* Where:
* Flags:
*
* .pdb files:
* R - regex, H - host-only, followed by (optional) 3-digit hexnumber representing
* flags that should be filtered.
* [i.e. phishcheck urls.flags that we don't want to be done for this particular host]
*
* .wdb files:
* X - full URL regex
* Y - host-only regex
* M - host simple pattern
*
* If a line in the file doesn't conform to this format, loading fails
*
*/
while(cli_dbgets(buffer, FILEBUFF, fd, dbio)) {
char* pattern;
char* flags;
size_t pattern_len;
cli_chomp(buffer);
line++;
if(!*buffer)
continue;/* skip empty lines */
if(functionality_level_check(buffer))
continue;
if(engine->cb_sigload && engine->cb_sigload("phishing", buffer, engine->cb_sigload_ctx)) {
cli_dbgmsg("load_regex_matcher: skipping %s due to callback\n", buffer);
continue;
}
entry++;
pattern = strchr(buffer,':');
if(!pattern) {
cli_errmsg("Malformed regex list line %d\n",line);
fatal_error(matcher);
return CL_EMALFDB;
}
/*pattern[0]='\0';*/
flags = buffer+1;
pattern++;
pattern_len = strlen(pattern);
if(pattern_len < FILEBUFF) {
pattern[pattern_len] = '/';
pattern[pattern_len+1] = '\0';
}
else {
cli_errmsg("Overlong regex line %d\n",line);
fatal_error(matcher);
return CL_EMALFDB;
}
if((buffer[0] == 'R' && !is_whitelist) || ((buffer[0] == 'X' || buffer[0] == 'Y') && is_whitelist)) {
/* regex for hostname*/
if (( rc = regex_list_add_pattern(matcher, pattern) ))
return rc==CL_EMEM ? CL_EMEM : CL_EMALFDB;
}
else if( ( buffer[0] == 'H' && !is_whitelist) || (buffer[0] == 'M' && is_whitelist)) {
/*matches displayed host*/
if (( rc = add_static_pattern(matcher, pattern) ))
return rc==CL_EMEM ? CL_EMEM : CL_EMALFDB;
} else if (buffer[0] == 'S' && (!is_whitelist || pattern[0]=='W')) {
pattern[pattern_len] = '\0';
if (pattern[0]=='W')
flags[0]='W';
if((pattern[0]=='W' || pattern[0]=='F' || pattern[0]=='P') && pattern[1]==':') {
pattern += 2;
if (( rc = add_hash(matcher, pattern, flags[0], pattern[-2] == 'P') )) {
cli_errmsg("Error loading at line: %d\n", line);
return rc==CL_EMEM ? CL_EMEM : CL_EMALFDB;
}
} else {
cli_errmsg("Error loading line: %d, %c\n", line, *pattern);
return CL_EMALFDB;
}
} else {
return CL_EMALFDB;
}
}
matcher->list_loaded = 1;
if(signo)
*signo += entry;
return CL_SUCCESS;
}
/* Build the matcher list */
int cli_build_regex_list(struct regex_matcher* matcher)
{
int rc;
if(!matcher)
return CL_SUCCESS;
if(!matcher->list_inited || !matcher->list_loaded) {
cli_errmsg("Regex list not loaded!\n");
return -1;/*TODO: better error code */
}
cli_dbgmsg("Building regex list\n");
cli_hashtab_free(&matcher->suffix_hash);
if(( rc = cli_ac_buildtrie(&matcher->suffixes) ))
return rc;
matcher->list_built=1;
cli_hashset_destroy(&matcher->sha256_pfx_set);
return CL_SUCCESS;
}
/* Done with this matcher, free resources */
void regex_list_done(struct regex_matcher* matcher)
{
assert(matcher);
if(matcher->list_inited == 1) {
size_t i;
cli_ac_free(&matcher->suffixes);
if(matcher->suffix_regexes) {
for(i=0;i<matcher->suffix_cnt;i++) {
struct regex_list *r = matcher->suffix_regexes[i].head;
while(r) {
struct regex_list *q = r;
r = r->nxt;
free(q->pattern);
free(q);
}
}
free(matcher->suffix_regexes);
matcher->suffix_regexes = NULL;
}
if(matcher->all_pregs) {
for(i=0;i<matcher->regex_cnt;i++) {
regex_t *r = matcher->all_pregs[i];
cli_regfree(r);
mpool_free(matcher->mempool, r);
}
mpool_free(matcher->mempool, matcher->all_pregs);
}
cli_hashtab_free(&matcher->suffix_hash);
cli_bm_free(&matcher->sha256_hashes);
cli_bm_free(&matcher->hostkey_prefix);
}
}
int is_regex_ok(struct regex_matcher* matcher)
{
assert(matcher);
return (!matcher->list_inited || matcher->list_inited!=-1);/* either we don't have a regexlist, or we initialized it successfully */
}
static int add_newsuffix(struct regex_matcher *matcher, struct regex_list *info, const char *suffix, size_t len)
{
struct cli_matcher *root = &matcher->suffixes;
struct cli_ac_patt *new = mpool_calloc(matcher->mempool,1,sizeof(*new));
size_t i;
int ret;
if(!new)
return CL_EMEM;
assert(root && suffix);
new->rtype = 0;
new->type = 0;
new->sigid = 0;
new->parts = 0;
new->partno = 0;
new->mindist = 0;
new->maxdist = 0;
new->offset_min = CLI_OFF_ANY;
new->length = len;
new->ch[0] = new->ch[1] |= CLI_MATCH_IGNORE;
if(new->length > root->maxpatlen)
root->maxpatlen = new->length;
new->pattern = mpool_malloc(matcher->mempool, sizeof(new->pattern[0])*len);
if(!new->pattern) {
mpool_free(matcher->mempool, new);
return CL_EMEM;
}
for(i=0;i<len;i++)
new->pattern[i] = suffix[i];/*new->pattern is short int* */
new->customdata = info;
new->virname = NULL;
if((ret = cli_ac_addpatt(root,new))) {
mpool_free(matcher->mempool, new->pattern);
mpool_free(matcher->mempool, new);
return ret;
}
filter_add_static(&matcher->filter, (const unsigned char*)suffix, len, "regex");
return CL_SUCCESS;
}
#define MODULE "regex_list: "
/* ------ load a regex, determine suffix, determine suffix2regexlist map ---- */
static void list_add_tail(struct regex_list_ht *ht, struct regex_list *regex)
{
if(!ht->head)
ht->head = regex;
if(ht->tail) {
ht->tail->nxt = regex;
}
ht->tail = regex;
}
/* returns 0 on success, clamav error code otherwise */
static int add_pattern_suffix(void *cbdata, const char *suffix, size_t suffix_len, const struct regex_list *iregex)
{
struct regex_matcher *matcher = cbdata;
struct regex_list *regex = cli_malloc(sizeof(*regex));
const struct cli_element *el;
assert(matcher);
if(!regex)
return CL_EMEM;
regex->pattern = iregex->pattern ? cli_strdup(iregex->pattern) : NULL;
regex->preg = iregex->preg;
regex->nxt = NULL;
el = cli_hashtab_find(&matcher->suffix_hash, suffix, suffix_len);
/* TODO: what if suffixes are prefixes of eachother and only one will
* match? */
if(el) {
/* existing suffix */
assert((size_t)el->data < matcher->suffix_cnt);
list_add_tail(&matcher->suffix_regexes[el->data], regex);
} else {
/* new suffix */
size_t n = matcher->suffix_cnt++;
el = cli_hashtab_insert(&matcher->suffix_hash, suffix, suffix_len, n);
matcher->suffix_regexes = cli_realloc(matcher->suffix_regexes, (n+1)*sizeof(*matcher->suffix_regexes));
if(!matcher->suffix_regexes)
return CL_EMEM;
matcher->suffix_regexes[n].tail = regex;
matcher->suffix_regexes[n].head = regex;
if (suffix[0] == '/' && suffix[1] == '\0')
matcher->root_regex_idx = n;
add_newsuffix(matcher, regex, suffix, suffix_len);
}
return 0;
}
static size_t reverse_string(char *pattern)
{
size_t len = strlen(pattern);
size_t i;
for(i=0; i < (len/2); i++) {
char aux = pattern[i];
pattern[i] = pattern[len-i-1];
pattern[len-i-1] = aux;
}
return len;
}
static regex_t *new_preg(struct regex_matcher *matcher)
{
regex_t *r;
matcher->all_pregs = mpool_realloc(matcher->mempool, matcher->all_pregs, ++matcher->regex_cnt * sizeof(*matcher->all_pregs));
if(!matcher->all_pregs)
return NULL;
r = mpool_malloc(matcher->mempool, sizeof(*r));
if(!r)
return NULL;
matcher->all_pregs[matcher->regex_cnt-1] = r;
return r;
}
static int add_static_pattern(struct regex_matcher *matcher, char* pattern)
{
size_t len;
struct regex_list regex;
int rc;
len = reverse_string(pattern);
regex.nxt = NULL;
regex.pattern = cli_strdup(pattern);
regex.preg = NULL;
rc = add_pattern_suffix(matcher, pattern, len, ®ex);
free(regex.pattern);
return rc;
}
int regex_list_add_pattern(struct regex_matcher *matcher, char *pattern)
{
int rc;
regex_t *preg;
size_t len;
/* we only match the host, so remove useless stuff */
const char remove_end[] = "([/?].*)?/";
const char remove_end2[] = "([/?].*)/";
len = strlen(pattern);
if(len > sizeof(remove_end)) {
if(strncmp(&pattern[len - sizeof(remove_end)+1], remove_end, sizeof(remove_end)-1) == 0) {
len -= sizeof(remove_end) - 1;
pattern[len++]='/';
}
if(strncmp(&pattern[len - sizeof(remove_end2)+1], remove_end2, sizeof(remove_end2)-1) == 0) {
len -= sizeof(remove_end2) - 1;
pattern[len++]='/';
}
}
pattern[len] = '\0';
preg = new_preg(matcher);
if(!preg)
return CL_EMEM;
rc = cli_regex2suffix(pattern, preg, add_pattern_suffix, (void*)matcher);
if(rc) {
cli_regfree(preg);
}
return rc;
}