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Diffstat (limited to 'match.c')
| -rw-r--r-- | match.c | 364 |
1 files changed, 364 insertions, 0 deletions
@@ -0,0 +1,364 @@ +/* $OpenBSD: match.c,v 1.43 2020/11/03 22:53:12 djm Exp $ */ +/* + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + * Simple pattern matching, with '*' and '?' as wildcards. + * + * As far as I am concerned, the code I have written for this software + * can be used freely for any purpose. Any derived versions of this + * software must be clearly marked as such, and if the derived work is + * incompatible with the protocol description in the RFC file, it must be + * called by a name other than "ssh" or "Secure Shell". + */ +/* + * Copyright (c) 2000 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "includes.h" + +#include <sys/types.h> + +#include <ctype.h> +#include <stdlib.h> +#include <string.h> +#include <stdarg.h> +#include <stdio.h> + +#include "xmalloc.h" +#include "match.h" +#include "misc.h" + +/* + * Returns true if the given string matches the pattern (which may contain ? + * and * as wildcards), and zero if it does not match. + */ +int +match_pattern(const char *s, const char *pattern) +{ + for (;;) { + /* If at end of pattern, accept if also at end of string. */ + if (!*pattern) + return !*s; + + if (*pattern == '*') { + /* Skip this and any consecutive asterisks. */ + while (*pattern == '*') + pattern++; + + /* If at end of pattern, accept immediately. */ + if (!*pattern) + return 1; + + /* If next character in pattern is known, optimize. */ + if (*pattern != '?' && *pattern != '*') { + /* + * Look instances of the next character in + * pattern, and try to match starting from + * those. + */ + for (; *s; s++) + if (*s == *pattern && + match_pattern(s + 1, pattern + 1)) + return 1; + /* Failed. */ + return 0; + } + /* + * Move ahead one character at a time and try to + * match at each position. + */ + for (; *s; s++) + if (match_pattern(s, pattern)) + return 1; + /* Failed. */ + return 0; + } + /* + * There must be at least one more character in the string. + * If we are at the end, fail. + */ + if (!*s) + return 0; + + /* Check if the next character of the string is acceptable. */ + if (*pattern != '?' && *pattern != *s) + return 0; + + /* Move to the next character, both in string and in pattern. */ + s++; + pattern++; + } + /* NOTREACHED */ +} + +/* + * Tries to match the string against the + * comma-separated sequence of subpatterns (each possibly preceded by ! to + * indicate negation). Returns -1 if negation matches, 1 if there is + * a positive match, 0 if there is no match at all. + */ +int +match_pattern_list(const char *string, const char *pattern, int dolower) +{ + char sub[1024]; + int negated; + int got_positive; + u_int i, subi, len = strlen(pattern); + + got_positive = 0; + for (i = 0; i < len;) { + /* Check if the subpattern is negated. */ + if (pattern[i] == '!') { + negated = 1; + i++; + } else + negated = 0; + + /* + * Extract the subpattern up to a comma or end. Convert the + * subpattern to lowercase. + */ + for (subi = 0; + i < len && subi < sizeof(sub) - 1 && pattern[i] != ','; + subi++, i++) + sub[subi] = dolower && isupper((u_char)pattern[i]) ? + tolower((u_char)pattern[i]) : pattern[i]; + /* If subpattern too long, return failure (no match). */ + if (subi >= sizeof(sub) - 1) + return 0; + + /* If the subpattern was terminated by a comma, then skip it. */ + if (i < len && pattern[i] == ',') + i++; + + /* Null-terminate the subpattern. */ + sub[subi] = '\0'; + + /* Try to match the subpattern against the string. */ + if (match_pattern(string, sub)) { + if (negated) + return -1; /* Negative */ + else + got_positive = 1; /* Positive */ + } + } + + /* + * Return success if got a positive match. If there was a negative + * match, we have already returned -1 and never get here. + */ + return got_positive; +} + +/* Match a list representing users or groups. */ +int +match_usergroup_pattern_list(const char *string, const char *pattern) +{ +#ifdef HAVE_CYGWIN + /* Windows usernames may be Unicode and are not case sensitive */ + return cygwin_ug_match_pattern_list(string, pattern); +#else + /* Case sensitive match */ + return match_pattern_list(string, pattern, 0); +#endif +} + +/* + * Tries to match the host name (which must be in all lowercase) against the + * comma-separated sequence of subpatterns (each possibly preceded by ! to + * indicate negation). Returns -1 if negation matches, 1 if there is + * a positive match, 0 if there is no match at all. + */ +int +match_hostname(const char *host, const char *pattern) +{ + char *hostcopy = xstrdup(host); + int r; + + lowercase(hostcopy); + r = match_pattern_list(hostcopy, pattern, 1); + free(hostcopy); + return r; +} + +/* + * returns 0 if we get a negative match for the hostname or the ip + * or if we get no match at all. returns -1 on error, or 1 on + * successful match. + */ +int +match_host_and_ip(const char *host, const char *ipaddr, + const char *patterns) +{ + int mhost, mip; + + if ((mip = addr_match_list(ipaddr, patterns)) == -2) + return -1; /* error in ipaddr match */ + else if (host == NULL || ipaddr == NULL || mip == -1) + return 0; /* negative ip address match, or testing pattern */ + + /* negative hostname match */ + if ((mhost = match_hostname(host, patterns)) == -1) + return 0; + /* no match at all */ + if (mhost == 0 && mip == 0) + return 0; + return 1; +} + +/* + * Match user, user@host_or_ip, user@host_or_ip_list against pattern. + * If user, host and ipaddr are all NULL then validate pattern/ + * Returns -1 on invalid pattern, 0 on no match, 1 on match. + */ +int +match_user(const char *user, const char *host, const char *ipaddr, + const char *pattern) +{ + char *p, *pat; + int ret; + + /* test mode */ + if (user == NULL && host == NULL && ipaddr == NULL) { + if ((p = strchr(pattern, '@')) != NULL && + match_host_and_ip(NULL, NULL, p + 1) < 0) + return -1; + return 0; + } + + if ((p = strchr(pattern, '@')) == NULL) + return match_pattern(user, pattern); + + pat = xstrdup(pattern); + p = strchr(pat, '@'); + *p++ = '\0'; + + if ((ret = match_pattern(user, pat)) == 1) + ret = match_host_and_ip(host, ipaddr, p); + free(pat); + + return ret; +} + +/* + * Returns first item from client-list that is also supported by server-list, + * caller must free the returned string. + */ +#define MAX_PROP 40 +#define SEP "," +char * +match_list(const char *client, const char *server, u_int *next) +{ + char *sproposals[MAX_PROP]; + char *c, *s, *p, *ret, *cp, *sp; + int i, j, nproposals; + + c = cp = xstrdup(client); + s = sp = xstrdup(server); + + for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0'; + (p = strsep(&sp, SEP)), i++) { + if (i < MAX_PROP) + sproposals[i] = p; + else + break; + } + nproposals = i; + + for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0'; + (p = strsep(&cp, SEP)), i++) { + for (j = 0; j < nproposals; j++) { + if (strcmp(p, sproposals[j]) == 0) { + ret = xstrdup(p); + if (next != NULL) + *next = (cp == NULL) ? + strlen(c) : (u_int)(cp - c); + free(c); + free(s); + return ret; + } + } + } + if (next != NULL) + *next = strlen(c); + free(c); + free(s); + return NULL; +} + +/* + * Filter proposal using pattern-list filter. + * "denylist" determines sense of filter: + * non-zero indicates that items matching filter should be excluded. + * zero indicates that only items matching filter should be included. + * returns NULL on allocation error, otherwise caller must free result. + */ +static char * +filter_list(const char *proposal, const char *filter, int denylist) +{ + size_t len = strlen(proposal) + 1; + char *fix_prop = malloc(len); + char *orig_prop = strdup(proposal); + char *cp, *tmp; + int r; + + if (fix_prop == NULL || orig_prop == NULL) { + free(orig_prop); + free(fix_prop); + return NULL; + } + + tmp = orig_prop; + *fix_prop = '\0'; + while ((cp = strsep(&tmp, ",")) != NULL) { + r = match_pattern_list(cp, filter, 0); + if ((denylist && r != 1) || (!denylist && r == 1)) { + if (*fix_prop != '\0') + strlcat(fix_prop, ",", len); + strlcat(fix_prop, cp, len); + } + } + free(orig_prop); + return fix_prop; +} + +/* + * Filters a comma-separated list of strings, excluding any entry matching + * the 'filter' pattern list. Caller must free returned string. + */ +char * +match_filter_denylist(const char *proposal, const char *filter) +{ + return filter_list(proposal, filter, 1); +} + +/* + * Filters a comma-separated list of strings, including only entries matching + * the 'filter' pattern list. Caller must free returned string. + */ +char * +match_filter_allowlist(const char *proposal, const char *filter) +{ + return filter_list(proposal, filter, 0); +} |