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-rw-r--r--lib/util/regex.c194
1 files changed, 194 insertions, 0 deletions
diff --git a/lib/util/regex.c b/lib/util/regex.c
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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 unsigned int lastval = INT_MAX / 10;
+ const unsigned int remainder = INT_MAX % 10;
+ unsigned int result = 0;
+ unsigned char ch;
+
+ while ((ch = *str++) != '\0') {
+ if (ch == '\\' && isdigit((unsigned int)str[0]))
+ ch = *str++;
+ else if (!isdigit(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);
+}