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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2023 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <regex.h>
#include <sudo_compat.h>
#include <sudo_debug.h>
#include <sudo_util.h>
#include <sudo_gettext.h>
static char errbuf[1024];
/*
* Parse a number between 0 and INT_MAX, handling escaped digits.
* Returns the number on success or -1 on error.
* Sets endp to the first non-matching character.
*/
static int
parse_num(const char *str, char **endp)
{
debug_decl(check_pattern, SUDO_DEBUG_UTIL);
const int lastval = INT_MAX / 10;
const int remainder = INT_MAX % 10;
int result = 0;
char ch;
while ((ch = *str++) != '\0') {
if (ch == '\\' && isdigit((unsigned char)str[0]))
ch = *str++;
else if (!isdigit((unsigned char)ch))
break;
ch -= '0';
if (result > lastval || (result == lastval && ch > remainder)) {
result = -1;
break;
}
result *= 10;
result += ch;
}
*endp = (char *)(str - 1);
debug_return_int(result);
}
/*
* Check pattern for invalid repetition sequences.
* This is implementation-specific behavior, not all regcomp(3) forbid them.
* Glibc allows it but uses excessive memory for repeated '+' ops.
*/
static int
check_pattern(const char *pattern)
{
debug_decl(check_pattern, SUDO_DEBUG_UTIL);
const char *cp = pattern;
int b1, b2 = 0;
char ch, *ep, prev = '\0';
while ((ch = *cp++) != '\0') {
switch (ch) {
case '\\':
if (*cp != '\0') {
/* Skip escaped character. */
cp++;
prev = '\0';
continue;
}
break;
case '?':
case '*':
case '+':
if (prev == '?' || prev == '*' || prev == '+' || prev == '{' ) {
/* Invalid repetition operator. */
debug_return_int(REG_BADRPT);
}
break;
case '{':
/*
* Try to match bound: {[0-9\\]*\?,[0-9\\]*}
* GNU libc supports escaped digits and commas.
*/
b1 = parse_num(cp, &ep);
switch (ep[0]) {
case '\\':
if (ep[1] != ',')
break;
ep++;
FALLTHROUGH;
case ',':
cp = ep + 1;
b2 = parse_num(cp, &ep);
break;
}
cp = ep;
if (*cp == '}') {
if (b1 < 0 || b1 > 255 || b2 < 0 || b2 > 255) {
/* Invalid bound value. */
debug_return_int(REG_BADBR);
}
if (prev == '?' || prev == '*' || prev == '+' || prev == '{' ) {
/* Invalid repetition operator. */
debug_return_int(REG_BADRPT);
}
/* Skip past '}', prev will be set to '{' below */
cp++;
break;
}
prev = '\0';
continue;
}
prev = ch;
}
debug_return_int(0);
}
/*
* Wrapper around regcomp() that handles a regex starting with (?i).
* Avoid using regex_t in the function args so we don't need to
* include regex.h everywhere.
*/
bool
sudo_regex_compile_v1(void *v, const char *pattern, const char **errstr)
{
int errcode, cflags = REG_EXTENDED|REG_NOSUB;
regex_t *preg;
char *copy = NULL;
const char *cp;
regex_t rebuf;
debug_decl(regex_compile, SUDO_DEBUG_UTIL);
/* Some callers just want to check the validity of the pattern. */
preg = v ? v : &rebuf;
/* Limit the length of regular expressions to avoid fuzzer issues. */
if (strlen(pattern) > 1024) {
*errstr = N_("regular expression too large");
debug_return_bool(false);
}
/* Check for (?i) to enable case-insensitive matching. */
cp = pattern[0] == '^' ? pattern + 1 : pattern;
if (strncmp(cp, "(?i)", 4) == 0) {
cflags |= REG_ICASE;
copy = strdup(pattern + 4);
if (copy == NULL) {
*errstr = N_("unable to allocate memory");
debug_return_bool(false);
}
if (pattern[0] == '^')
copy[0] = '^';
pattern = copy;
}
errcode = check_pattern(pattern);
if (errcode == 0)
errcode = regcomp(preg, pattern, cflags);
if (errcode == 0) {
if (preg == &rebuf)
regfree(&rebuf);
} else {
regerror(errcode, preg, errbuf, sizeof(errbuf));
*errstr = errbuf;
}
free(copy);
debug_return_bool(errcode == 0);
}
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