int cli_pcre_build(struct cli_matcher *root, long long unsigned match_limit, long long unsigned recmatch_limit, const struct cli_dconf *dconf)
{
unsigned int i;
int ret;
struct cli_pcre_meta *pm = NULL;
int disable_all = 0;
if (dconf && !(dconf->pcre & PCRE_CONF_SUPPORT))
disable_all = 1;
for (i = 0; i < root->pcre_metas; ++i) {
pm = root->pcre_metatable[i];
if (!pm) {
cli_errmsg("cli_pcre_build: metadata for pcre %d is missing\n", i);
return CL_ENULLARG;
}
/* for safety, disable all pcre */
if (disable_all) {
pm->flags |= CLI_PCRE_DISABLED;
continue;
}
if (pm->flags & CLI_PCRE_DISABLED) {
cli_dbgmsg("cli_pcre_build: Skip compiling regex: %s (disabled)\n", pm->pdata.expression);
continue;
}
/* disable global */
if (dconf && !(dconf->pcre & PCRE_CONF_GLOBAL)) {
cli_dbgmsg("cli_pcre_build: disabling global option for regex /%s/\n", pm->pdata.expression);
pm->flags &= ~(CLI_PCRE_GLOBAL);
}
/* options override through metadata manipulation */
#ifdef PCRE_NEVER_UTF
pm->pdata.options |= PCRE_NEVER_UTF; /* implemented in 8.33, disables (?UTF*) potential security vuln */
#endif
//pm->pdata.options |= PCRE_UCP;/* implemented in 8.20 */
//pm->pdata.options |= PCRE_AUTO_CALLOUT; /* used with CALLOUT(-BACK) function */
if (dconf && (dconf->pcre & PCRE_CONF_OPTIONS)) {
/* compile the regex, no options override *wink* */
pm_dbgmsg("cli_pcre_build: Compiling regex: /%s/\n", pm->pdata.expression);
ret = cli_pcre_compile(&(pm->pdata), match_limit, recmatch_limit, 0, 0);
}
else {
/* compile the regex, options overrided and disabled */
pm_dbgmsg("cli_pcre_build: Compiling regex: /%s/ (without options)\n", pm->pdata.expression);
ret = cli_pcre_compile(&(pm->pdata), match_limit, recmatch_limit, 0, 1);
}
if (ret != CL_SUCCESS) {
cli_errmsg("cli_pcre_build: failed to build pcre regex\n");
pm->flags |= CLI_PCRE_DISABLED; /* disable the pcre, currently will terminate execution */
return ret;
}
}
return CL_SUCCESS;
}
static void pcre_perf_events_init(struct cli_pcre_meta *pm, const char *virname)
{
int ret;
size_t namelen;
if (!p_sigevents) {
p_sigevents = cli_events_new(MAX_PCRE_SIGEVENT_ID);
if (!p_sigevents) {
cli_errmsg("pcre_perf: no memory for events table\n");
return;
}
}
if (p_sigid > MAX_PCRE_SIGEVENT_ID - PCRE_EVENTS_PER_SIG - 1) {
cli_errmsg("pcre_perf: events table full. Increase MAX_TRACKED_PCRE\n");
return;
}
if (!virname) {
virname = "(null)";
namelen = 7;
} else {
namelen = strlen(virname)+strlen(pm->pdata.expression)+3;
}
/* set the name */
pm->statname = (char*)cli_calloc(1, namelen);
if (!pm->statname) {
return;
}
snprintf(pm->statname, namelen, "%s/%s/", virname, pm->pdata.expression);
pm_dbgmsg("pcre_perf: adding sig ids starting %u for %s\n", p_sigid, pm->statname);
/* register time event */
pm->sigtime_id = p_sigid;
ret = cli_event_define(p_sigevents, p_sigid++, pm->statname, ev_time, multiple_sum);
if (ret) {
cli_errmsg("pcre_perf: cli_event_define() error for time event id %d\n", pm->sigtime_id);
pm->sigtime_id = MAX_PCRE_SIGEVENT_ID+1;
return;
}
/* register match count */
pm->sigmatch_id = p_sigid;
ret = cli_event_define(p_sigevents, p_sigid++, pm->statname, ev_int, multiple_sum);
if (ret) {
cli_errmsg("pcre_perf: cli_event_define() error for matches event id %d\n", pm->sigmatch_id);
pm->sigmatch_id = MAX_PCRE_SIGEVENT_ID+1;
return;
}
}
int cli_pcre_scanbuf(const unsigned char *buffer, uint32_t length, const char **virname, struct cli_ac_result **res, const struct cli_matcher *root, struct cli_ac_data *mdata, const struct cli_pcre_off *data, cli_ctx *ctx)
{
struct cli_pcre_meta **metatable = root->pcre_metatable, *pm = NULL;
struct cli_pcre_data *pd;
struct cli_pcre_results p_res;
struct cli_ac_result *newres;
uint32_t adjbuffer, adjshift, adjlength;
unsigned int i, evalcnt = 0;
uint64_t maxfilesize, evalids = 0;
uint32_t global, encompass, rolling;
int rc, offset, ret = CL_SUCCESS, options=0;
uint8_t viruses_found = 0;
if ((root->pcre_metas == 0) || (!root->pcre_metatable) || (ctx && ctx->dconf && !(ctx->dconf->pcre & PCRE_CONF_SUPPORT)))
return CL_SUCCESS;
memset(&p_res, 0, sizeof(p_res));
for (i = 0; i < root->pcre_metas; ++i) {
pm = root->pcre_metatable[i];
pd = &(pm->pdata);
/* skip checking and running disabled pcres */
if (pm->flags & CLI_PCRE_DISABLED) {
cli_dbgmsg("cli_pcre_scanbuf: skipping disabled regex /%s/\n", pd->expression);
continue;
}
/* skip checking and running CLI_OFF_NONE pcres */
if (data && data->offset[i] == CLI_OFF_NONE) {
pm_dbgmsg("cli_pcre_scanbuf: skipping CLI_OFF_NONE regex /%s/\n", pd->expression);
continue;
}
/* evaluate trigger */
if (pm->lsigid[0]) {
cli_dbgmsg("cli_pcre_scanbuf: checking %s; running regex /%s/\n", pm->trigger, pd->expression);
#ifdef PCRE_BYPASS
if (strcmp(pm->trigger, PCRE_BYPASS))
#endif
if (cli_ac_chklsig(pm->trigger, pm->trigger + strlen(pm->trigger), mdata->lsigcnt[pm->lsigid[1]], &evalcnt, &evalids, 0) != 1)
continue;
}
else {
cli_dbgmsg("cli_pcre_scanbuf: skipping %s check due to uninitialized lsigid\n", pm->trigger);
/* fall-through to unconditional execution - sigtool-only */
}
global = (pm->flags & CLI_PCRE_GLOBAL); /* globally search for all matches (within bounds) */
encompass = (pm->flags & CLI_PCRE_ENCOMPASS); /* encompass search to offset->offset+maxshift */
rolling = (pm->flags & CLI_PCRE_ROLLING); /* rolling search (unanchored) */
offset = pd->search_offset; /* this is usually 0 */
cli_dbgmsg("cli_pcre_scanbuf: triggered %s; running regex /%s/%s%s\n", pm->trigger, pd->expression,
global ? " (global)":"", rolling ? " (rolling)":"");
/* adjust the buffer sent to cli_pcre_match for offset and maxshift */
if (!data) {
if (cli_pcre_qoff(pm, length, &adjbuffer, &adjshift) != CL_SUCCESS)
continue;
}
else {
adjbuffer = data->offset[i];
adjshift = data->shift[i];
}
/* check for need to anchoring */
if (!rolling && !adjshift && (adjbuffer != CLI_OFF_ANY))
#if USING_PCRE2
options |= PCRE2_ANCHORED;
#else
options |= PCRE_ANCHORED;
#endif
else
options = 0;
if (adjbuffer == CLI_OFF_ANY)
adjbuffer = 0;
/* check the offset bounds */
if (adjbuffer < length) {
/* handle encompass flag */
if (encompass && adjshift != 0 && adjshift != CLI_OFF_NONE) {
if (adjbuffer+adjshift > length)
adjlength = length - adjbuffer;
else
adjlength = adjshift;
}
else {
/* NOTE - if using non-encompass method 2, alter shift universally */
/* TODO - limitations on non-encompassed buffers? */
adjlength = length - adjbuffer;
}
}
else {
/* starting offset is outside bounds of file, skip pcre execution silently */
pm_dbgmsg("cli_pcre_scanbuf: starting offset is outside bounds of file %u >= %u\n", adjbuffer, length);
continue;
}
pm_dbgmsg("cli_pcre_scanbuf: passed buffer adjusted to %u +%u(%u)[%u]%s\n", adjbuffer, adjlength, adjbuffer+adjlength, adjshift, encompass ? " (encompass)":"");
/* if the global flag is set, loop through the scanning */
do {
/* reset the match results */
if ((ret = cli_pcre_results_reset(&p_res, pd)) != CL_SUCCESS)
break;
/* performance metrics */
cli_event_time_start(p_sigevents, pm->sigtime_id);
rc = cli_pcre_match(pd, buffer+adjbuffer, adjlength, offset, options, &p_res);
cli_event_time_stop(p_sigevents, pm->sigtime_id);
/* if debug, generate a match report */
if (cli_debug_flag)
cli_pcre_report(pd, buffer+adjbuffer, adjlength, rc, &p_res);
/* matched, rc shouldn't be >0 unless a full match occurs */
if (rc > 0) {
cli_dbgmsg("cli_pcre_scanbuf: located regex match @ %d\n", adjbuffer+p_res.match[0]);
/* check if we've gone over offset+shift */
if (!encompass && adjshift) {
if (p_res.match[0] > adjshift) {
/* ignore matched offset (outside of maxshift) */
cli_dbgmsg("cli_pcre_scanbuf: match found outside of maxshift @%u\n", adjbuffer+p_res.match[0]);
break;
}
}
/* track the detection count */
cli_event_count(p_sigevents, pm->sigmatch_id);
/* for logical signature evaluation */
if (pm->lsigid[0]) {
pm_dbgmsg("cli_pcre_scanbuf: assigning lsigcnt[%d][%d], located @ %d\n",
pm->lsigid[1], pm->lsigid[2], adjbuffer+p_res.match[0]);
ret = lsig_sub_matched(root, mdata, pm->lsigid[1], pm->lsigid[2], adjbuffer+p_res.match[0], 0);
if (ret != CL_SUCCESS)
break;
} else {
/* for raw match data - sigtool only */
if(res) {
newres = (struct cli_ac_result *)cli_calloc(1, sizeof(struct cli_ac_result));
if(!newres) {
cli_errmsg("cli_pcre_scanbuff: Can't allocate memory for new result\n");
ret = CL_EMEM;
break;
}
newres->virname = pm->virname;
newres->customdata = NULL; /* get value? */
newres->next = *res;
newres->offset = adjbuffer+p_res.match[0];
*res = newres;
} else {
if (ctx && SCAN_ALL) {
viruses_found = 1;
cli_append_virus(ctx, (const char *)pm->virname);
}
if (virname)
*virname = pm->virname;
if (!ctx || !SCAN_ALL) {
ret = CL_VIRUS;
break;
}
}
}
}
/* move off to the end of the match for next match; offset is relative to adjbuffer
* NOTE: misses matches starting within the last match; TODO: start from start of last match? */
offset = p_res.match[1];
} while (global && rc > 0 && offset < adjlength);
/* handle error code */
if (rc < 0 && p_res.err != CL_SUCCESS)
ret = p_res.err;
/* jumps out of main loop from 'global' loop */
if (ret != CL_SUCCESS)
break;
}
/* TODO - handle VI and Macro offset types */
int cli_pcre_recaloff(struct cli_matcher *root, struct cli_pcre_off *data, struct cli_target_info *info, cli_ctx *ctx)
{
/* TANGENT: maintain relative offset data in cli_ac_data? */
int ret;
unsigned int i;
struct cli_pcre_meta *pm;
uint32_t endoff;
if (!data) {
return CL_ENULLARG;
}
if (!root || !root->pcre_metatable || !info || (ctx && ctx->dconf && !(ctx->dconf->pcre & PCRE_CONF_SUPPORT))) {
data->shift = NULL;
data->offset = NULL;
return CL_SUCCESS;
}
/* allocate data structures */
data->shift = (uint32_t *) cli_calloc(root->pcre_metas, sizeof(uint32_t));
if (!data->shift) {
cli_errmsg("cli_pcre_initoff: cannot allocate memory for data->shift\n");
return CL_EMEM;
}
data->offset = (uint32_t *) cli_calloc(root->pcre_metas, sizeof(uint32_t));
if (!data->offset) {
cli_errmsg("cli_pcre_initoff: cannot allocate memory for data->offset\n");
free(data->shift);
return CL_EMEM;
}
pm_dbgmsg("CLI_OFF_NONE: %u\n", CLI_OFF_NONE);
pm_dbgmsg("CLI_OFF_ANY: %u\n", CLI_OFF_ANY);
/* iterate across all pcre metadata and recalc offsets */
for (i = 0; i < root->pcre_metas; ++i) {
pm = root->pcre_metatable[i];
/* skip broken pcres, not getting executed anyways */
if (pm->flags & CLI_PCRE_DISABLED) {
data->offset[i] = CLI_OFF_NONE;
data->shift[i] = 0;
continue;
}
if (pm->offdata[0] == CLI_OFF_ANY) {
data->offset[i] = CLI_OFF_ANY;
data->shift[i] = 0;
}
else if (pm->offdata[0] == CLI_OFF_NONE) {
data->offset[i] = CLI_OFF_NONE;
data->shift[i] = 0;
}
else if (pm->offdata[0] == CLI_OFF_ABSOLUTE) {
data->offset[i] = pm->offdata[1];
data->shift[i] = pm->offdata[2];
}
else {
ret = cli_caloff(NULL, info, root->type, pm->offdata, &data->offset[i], &endoff);
if (ret != CL_SUCCESS) {
cli_errmsg("cli_pcre_recaloff: cannot recalculate relative offset for signature\n");
free(data->shift);
free(data->offset);
return ret;
}
/* CLI_OFF_NONE gets passed down, CLI_OFF_ANY gets reinterpreted */
/* TODO - CLI_OFF_VERSION is interpreted as CLI_OFF_ANY(?) */
if (data->offset[i] == CLI_OFF_ANY) {
data->offset[i] = CLI_OFF_ANY;
data->shift[i] = 0;
}
else {
data->shift[i] = endoff-(data->offset[i]);
}
}
pm_dbgmsg("%u: %u %u->%u(+%u)\n", i, pm->offdata[0], data->offset[i],
data->offset[i]+data->shift[i], data->shift[i]);
}
return CL_SUCCESS;
}
int cli_pcre_addpatt(struct cli_matcher *root, const char *virname, const char *trigger, const char *pattern, const char *cflags, const char *offset, const uint32_t *lsigid, unsigned int options)
{
struct cli_pcre_meta **newmetatable = NULL, *pm = NULL;
uint32_t pcre_count;
const char *opt;
int ret = CL_SUCCESS, rssigs;
if (!root || !trigger || !pattern || !offset) {
cli_errmsg("cli_pcre_addpatt: NULL root or NULL trigger or NULL pattern or NULL offset\n");
return CL_ENULLARG;
}
/* TODO: trigger and regex checking (backreference limitations?) (control pattern limitations?) */
/* cli_ac_chklsig will fail a empty trigger; empty patterns can cause an infinite loop */
if (*trigger == '\0' || *pattern == '\0') {
cli_errmsg("cli_pcre_addpatt: trigger or pattern cannot be an empty string\n");
return CL_EMALFDB;
}
if (cflags && *cflags == '\0') {
cflags = NULL;
}
if (lsigid)
pm_dbgmsg("cli_pcre_addpatt: Adding /%s/%s%s triggered on (%s) as subsig %d for lsigid %d\n",
pattern, cflags ? " with flags " : "", cflags ? cflags : "", trigger, lsigid[1], lsigid[0]);
else
pm_dbgmsg("cli_pcre_addpatt: Adding /%s/%s%s triggered on (%s) [no lsigid]\n",
pattern, cflags ? " with flags " : "", cflags ? cflags : "", trigger);
#ifdef PCRE_BYPASS
/* check for trigger bypass */
if (strcmp(trigger, PCRE_BYPASS)) {
#endif
/* validate the lsig trigger */
rssigs = cli_ac_chklsig(trigger, trigger + strlen(trigger), NULL, NULL, NULL, 1);
if(rssigs == -1) {
cli_errmsg("cli_pcre_addpatt: regex subsig /%s/ is missing a valid logical trigger\n", pattern);
return CL_EMALFDB;
}
if (lsigid) {
if (rssigs > lsigid[1]) {
cli_errmsg("cli_pcre_addpatt: regex subsig %d logical trigger refers to subsequent subsig %d\n", lsigid[1], rssigs);
return CL_EMALFDB;
}
if (rssigs == lsigid[1]) {
cli_errmsg("cli_pcre_addpatt: regex subsig %d logical trigger is self-referential\n", lsigid[1]);
return CL_EMALFDB;
}
}
else {
cli_dbgmsg("cli_pcre_addpatt: regex subsig is missing lsigid data\n");
}
#ifdef PCRE_BYPASS
}
#endif
/* allocating entries */
pm = (struct cli_pcre_meta *)mpool_calloc(root->mempool, 1, sizeof(*pm));
if (!pm) {
cli_errmsg("cli_pcre_addpatt: Unable to allocate memory for new pcre meta\n");
return CL_EMEM;
}
pm->trigger = cli_mpool_strdup(root->mempool, trigger);
if (!pm->trigger) {
cli_errmsg("cli_pcre_addpatt: Unable to allocate memory for trigger string\n");
cli_pcre_freemeta(root, pm);
mpool_free(root->mempool, pm);
return CL_EMEM;
}
pm->virname = (char *)cli_mpool_virname(root->mempool, virname, options & CL_DB_OFFICIAL);
if(!pm->virname) {
cli_errmsg("cli_pcre_addpatt: Unable to allocate memory for virname or NULL virname\n");
cli_pcre_freemeta(root, pm);
mpool_free(root->mempool, pm);
return CL_EMEM;
}
if (lsigid) {
root->ac_lsigtable[lsigid[0]]->virname = pm->virname;
pm->lsigid[0] = 1;
pm->lsigid[1] = lsigid[0];
pm->lsigid[2] = lsigid[1];
}
else {
/* sigtool */
pm->lsigid[0] = 0;
}
pm->pdata.expression = strdup(pattern);
if (!pm->pdata.expression) {
cli_errmsg("cli_pcre_addpatt: Unable to allocate memory for expression\n");
cli_pcre_freemeta(root, pm);
mpool_free(root->mempool, pm);
return CL_EMEM;
}
/* offset parsing and usage, similar to cli_ac_addsig */
/* relative and type-specific offsets handled during scan */
ret = cli_caloff(offset, NULL, root->type, pm->offdata, &(pm->offset_min), &(pm->offset_max));
if (ret != CL_SUCCESS) {
cli_errmsg("cli_pcre_addpatt: cannot calculate offset data: %s for pattern: %s\n", offset, pattern);
cli_pcre_freemeta(root, pm);
mpool_free(root->mempool, pm);
return ret;
}
if(pm->offdata[0] != CLI_OFF_ANY) {
if(pm->offdata[0] == CLI_OFF_ABSOLUTE)
root->pcre_absoff_num++;
else
root->pcre_reloff_num++;
}
/* parse and add options, also totally not from snort */
if (cflags) {
opt = cflags;
/* cli_pcre_addoptions handles pcre specific options */
while (cli_pcre_addoptions(&(pm->pdata), &opt, 0) != CL_SUCCESS) {
/* handle matcher specific options here */
switch (*opt) {
case 'g': pm->flags |= CLI_PCRE_GLOBAL; break;
case 'r': pm->flags |= CLI_PCRE_ROLLING; break;
case 'e': pm->flags |= CLI_PCRE_ENCOMPASS; break;
default:
cli_errmsg("cli_pcre_addpatt: unknown/extra pcre option encountered %c\n", *opt);
cli_pcre_freemeta(root, pm);
mpool_free(root->mempool, pm);
return CL_EMALFDB;
}
opt++;
}
if (pm->flags) {
pm_dbgmsg("Matcher: %s%s%s\n",
pm->flags & CLI_PCRE_GLOBAL ? "CLAMAV_GLOBAL " : "",
pm->flags & CLI_PCRE_ROLLING ? "CLAMAV_ROLLING " : "",
pm->flags & CLI_PCRE_ENCOMPASS ? "CLAMAV_ENCOMPASS " : "");
}
else
pm_dbgmsg("Matcher: NONE\n");
if (pm->pdata.options) {
#if USING_PCRE2
pm_dbgmsg("Compiler: %s%s%s%s%s%s%s\n",
pm->pdata.options & PCRE2_CASELESS ? "PCRE2_CASELESS " : "",
pm->pdata.options & PCRE2_DOTALL ? "PCRE2_DOTALL " : "",
pm->pdata.options & PCRE2_MULTILINE ? "PCRE2_MULTILINE " : "",
pm->pdata.options & PCRE2_EXTENDED ? "PCRE2_EXTENDED " : "",
pm->pdata.options & PCRE2_ANCHORED ? "PCRE2_ANCHORED " : "",
pm->pdata.options & PCRE2_DOLLAR_ENDONLY ? "PCRE2_DOLLAR_ENDONLY " : "",
pm->pdata.options & PCRE2_UNGREEDY ? "PCRE2_UNGREEDY " : "");
#else
pm_dbgmsg("Compiler: %s%s%s%s%s%s%s\n",
pm->pdata.options & PCRE_CASELESS ? "PCRE_CASELESS " : "",
pm->pdata.options & PCRE_DOTALL ? "PCRE_DOTALL " : "",
pm->pdata.options & PCRE_MULTILINE ? "PCRE_MULTILINE " : "",
pm->pdata.options & PCRE_EXTENDED ? "PCRE_EXTENDED " : "",
pm->pdata.options & PCRE_ANCHORED ? "PCRE_ANCHORED " : "",
pm->pdata.options & PCRE_DOLLAR_ENDONLY ? "PCRE_DOLLAR_ENDONLY " : "",
pm->pdata.options & PCRE_UNGREEDY ? "PCRE_UNGREEDY " : "");
#endif
}
else
pm_dbgmsg("Compiler: NONE\n");
}
/* add metadata to the performance tracker */
if (options & CL_DB_PCRE_STATS)
pcre_perf_events_init(pm, virname);
/* add pcre data to root after reallocation */
pcre_count = root->pcre_metas+1;
newmetatable = (struct cli_pcre_meta **)mpool_realloc(root->mempool, root->pcre_metatable,
pcre_count * sizeof(struct cli_pcre_meta *));
if (!newmetatable) {
cli_errmsg("cli_pcre_addpatt: Unable to allocate memory for new pcre meta table\n");
cli_pcre_freemeta(root, pm);
mpool_free(root->mempool, pm);
return CL_EMEM;
}
newmetatable[pcre_count-1] = pm;
root->pcre_metatable = newmetatable;
root->pcre_metas = pcre_count;
return CL_SUCCESS;
}