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feat: Allow regular expressions in ctl:ruleRemoveTargetByX variable names II. #3121

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feat: Allow regular expressions in ctl:ruleRemoveTargetByX variable names II. #3121

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be37489
Allow regular expressions in ctl:ruleRemoveTargetByX variable names II.
airween Apr 16, 2024
2b2535c
Split error handling into two parts; add regular log in case of faile…
airween Apr 17, 2024
c796804
Pre-calculate string length instead of strlen()
airween Apr 17, 2024
1790659
Statement simplification
airween Apr 17, 2024
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56 changes: 48 additions & 8 deletions apache2/re.c
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,11 @@ static int fetch_target_exception(msre_rule *rule, modsec_rec *msr, msre_var *va
char *c = NULL, *name = NULL, *value = NULL;
char *variable = NULL, *myvar = NULL;
char *myvalue = NULL, *myname = NULL;
msc_regex_t *regex;
char *errptr;
int erroffset;
int match = 0;
size_t value_len;

if(msr == NULL)
return 0;
Expand Down Expand Up @@ -111,23 +115,59 @@ static int fetch_target_exception(msre_rule *rule, modsec_rec *msr, msre_var *va
value = NULL;
}

value_len = 0;
if (value != NULL) {
value_len = strlen(value);
}

if((strlen(myname) == strlen(name)) &&
(strncasecmp(myname, name,strlen(myname)) == 0)) {
(strncasecmp(myname, name, strlen(myname)) == 0)) {

if(value != NULL && myvalue != NULL) {
if((strlen(myvalue) == strlen(value)) &&
if(value_len > 2 && value[0] == '/' && value[value_len - 1] == '/') {
value[value_len - 1] = '\0';
#ifdef WITH_PCRE2
regex = msc_pregcomp(msr->mp, value + 1,
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This (copied) code contains a memory leak: the regex variable compiled in each cycle during the exclusion check, but never freed (never called msc_pcre_cleanup()).

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We should reorganize this part. I would expect that regex variable above must be compiled during startup, and not when the engine inspect the exclusion.

PCRE2_DOTALL | PCRE2_CASELESS | PCRE2_DOLLAR_ENDONLY, (const char **)&errptr, &erroffset);
#else
regex = msc_pregcomp(msr->mp, value + 1,
PCRE_DOTALL | PCRE_CASELESS | PCRE_DOLLAR_ENDONLY, (const char **)&errptr, &erroffset);
#endif
if (regex == NULL) {
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If needed, logging should be added in msc_pregcomp(), so it's available for all calls

if (msr->txcfg->debuglog_level >= 9) {
#ifdef WITH_PCRE2
// in case of PCRE2 the errptr won't fill
msr_log(msr, 9, "fetch_target_exception: Regexp /%s/ failed to compile at pos %d.",
value + 1, erroffset);
ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL, " ModSecurity: exclusion regexp /%s/ failed to compile at pos %d.",
value + 1, erroffset);
#else
msr_log(msr, 9, "fetch_target_exception: Regexp /%s/ failed to compile at pos %d: %s.",
value + 1, erroffset, errptr);
ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL, " ModSecurity: exclusion regexp /%s/ failed to compile at pos %d: %s.",
value + 1, erroffset, errptr);
#endif
}
} else {
#ifdef WITH_PCRE2
if (!(msc_regexec(regex, myvalue, strlen(myvalue), &errptr) == PCRE2_ERROR_NOMATCH)) {
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@marcstern marcstern Aug 21, 2024 •
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Correct check is if (msc_regexec(...) < 0)
Same for PCRE2

#else
if (!(msc_regexec(regex, myvalue, strlen(myvalue), &errptr) == PCRE_ERROR_NOMATCH)) {
#endif
if (msr->txcfg->debuglog_level >= 9) {
msr_log(msr, 9, "fetch_target_exception: Target %s will not be processed.", var->name);
}
match = 1;
}
}
} else if((strlen(myvalue) == value_len) &&
strncasecmp(myvalue,value,strlen(myvalue)) == 0) {
if (msr->txcfg->debuglog_level >= 9) {
msr_log(msr, 9, "fetch_target_exception: Target %s will not be processed.", target);
}
match = 1;
}
} else if (value == NULL && myvalue == NULL) {
if (msr->txcfg->debuglog_level >= 9) {
msr_log(msr, 9, "fetch_target_exception: Target %s will not be processed.", target);
}
match = 1;
} else if (value == NULL && myvalue != NULL) {
} else {
if (msr->txcfg->debuglog_level >= 9) {
msr_log(msr, 9, "fetch_target_exception: Target %s will not be processed.", target);
}
Expand Down
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