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Diffstat (limited to 'lib/util/regex.c')
| -rw-r--r-- | lib/util/regex.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/lib/util/regex.c b/lib/util/regex.c new file mode 100644 index 0000000..1f91b4d --- /dev/null +++ b/lib/util/regex.c @@ -0,0 +1,194 @@ +/* + * 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); +} |