1 /* $NetBSD: acl.c,v 1.3 2023/06/19 21:41:44 christos Exp $ */
2
3 /*
4 * Copyright (c) 2000 - 2002, 2004 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include "krb5_locl.h"
37 #include <fnmatch.h>
38
39 struct acl_field {
40 enum { acl_string, acl_fnmatch, acl_retval } type;
41 union {
42 const char *cstr;
43 char **retv;
44 } u;
45 struct acl_field *next, **last;
46 };
47
48 static void
free_retv(struct acl_field * acl)49 free_retv(struct acl_field *acl)
50 {
51 while(acl != NULL) {
52 if (acl->type == acl_retval) {
53 if (*acl->u.retv)
54 free(*acl->u.retv);
55 *acl->u.retv = NULL;
56 }
57 acl = acl->next;
58 }
59 }
60
61 static void
acl_free_list(struct acl_field * acl,int retv)62 acl_free_list(struct acl_field *acl, int retv)
63 {
64 struct acl_field *next;
65 if (retv)
66 free_retv(acl);
67 while(acl != NULL) {
68 next = acl->next;
69 free(acl);
70 acl = next;
71 }
72 }
73
74 static krb5_error_code
acl_parse_format(krb5_context context,struct acl_field ** acl_ret,const char * format,va_list ap)75 acl_parse_format(krb5_context context,
76 struct acl_field **acl_ret,
77 const char *format,
78 va_list ap)
79 {
80 const char *p;
81 struct acl_field *acl = NULL, *tmp;
82
83 for(p = format; *p != '\0'; p++) {
84 tmp = malloc(sizeof(*tmp));
85 if(tmp == NULL) {
86 acl_free_list(acl, 0);
87 return krb5_enomem(context);
88 }
89 if(*p == 's') {
90 tmp->type = acl_string;
91 tmp->u.cstr = va_arg(ap, const char*);
92 } else if(*p == 'f') {
93 tmp->type = acl_fnmatch;
94 tmp->u.cstr = va_arg(ap, const char*);
95 } else if(*p == 'r') {
96 tmp->type = acl_retval;
97 tmp->u.retv = va_arg(ap, char **);
98 *tmp->u.retv = NULL;
99 } else {
100 krb5_set_error_message(context, EINVAL,
101 N_("Unknown format specifier %c while "
102 "parsing ACL", "specifier"), *p);
103 acl_free_list(acl, 0);
104 free(tmp);
105 return EINVAL;
106 }
107 tmp->next = NULL;
108 if(acl == NULL)
109 acl = tmp;
110 else
111 *acl->last = tmp;
112 acl->last = &tmp->next;
113 }
114 *acl_ret = acl;
115 return 0;
116 }
117
118 static krb5_boolean
acl_match_field(krb5_context context,const char * string,struct acl_field * field)119 acl_match_field(krb5_context context,
120 const char *string,
121 struct acl_field *field)
122 {
123 if(field->type == acl_string) {
124 return !strcmp(field->u.cstr, string);
125 } else if(field->type == acl_fnmatch) {
126 return !fnmatch(field->u.cstr, string, 0);
127 } else if(field->type == acl_retval) {
128 *field->u.retv = strdup(string);
129 return TRUE;
130 }
131 return FALSE;
132 }
133
134 static krb5_boolean
acl_match_acl(krb5_context context,struct acl_field * acl,const char * string)135 acl_match_acl(krb5_context context,
136 struct acl_field *acl,
137 const char *string)
138 {
139 char buf[256];
140 while(strsep_copy(&string, " \t", buf, sizeof(buf)) != -1) {
141 if(buf[0] == '\0')
142 continue; /* skip ws */
143 if (acl == NULL)
144 return FALSE;
145 if(!acl_match_field(context, buf, acl)) {
146 return FALSE;
147 }
148 acl = acl->next;
149 }
150 if (acl)
151 return FALSE;
152 return TRUE;
153 }
154
155 /**
156 * krb5_acl_match_string matches ACL format against a string.
157 *
158 * The ACL format has three format specifiers: s, f, and r. Each
159 * specifier will retrieve one argument from the variable arguments
160 * for either matching or storing data. The input string is split up
161 * using " " (space) and "\t" (tab) as a delimiter; multiple and "\t"
162 * in a row are considered to be the same.
163 *
164 * List of format specifiers:
165 * - s Matches a string using strcmp(3) (case sensitive).
166 * - f Matches the string with fnmatch(3). Theflags
167 * argument (the last argument) passed to the fnmatch function is 0.
168 * - r Returns a copy of the string in the char ** passed in; the copy
169 * must be freed with free(3). There is no need to free(3) the
170 * string on error: the function will clean up and set the pointer
171 * to NULL.
172 *
173 * @param context Kerberos 5 context
174 * @param string string to match with
175 * @param format format to match
176 * @param ... parameter to format string
177 *
178 * @return Return an error code or 0.
179 *
180 *
181 * @code
182 * char *s;
183 *
184 * ret = krb5_acl_match_string(context, "foo", "s", "foo");
185 * if (ret)
186 * krb5_errx(context, 1, "acl didn't match");
187 * ret = krb5_acl_match_string(context, "foo foo baz/kaka",
188 * "ss", "foo", &s, "foo/\\*");
189 * if (ret) {
190 * // no need to free(s) on error
191 * assert(s == NULL);
192 * krb5_errx(context, 1, "acl didn't match");
193 * }
194 * free(s);
195 * @endcode
196 *
197 * @sa krb5_acl_match_file
198 * @ingroup krb5_support
199 */
200
201 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_acl_match_string(krb5_context context,const char * string,const char * format,...)202 krb5_acl_match_string(krb5_context context,
203 const char *string,
204 const char *format,
205 ...)
206 {
207 krb5_error_code ret;
208 krb5_boolean found;
209 struct acl_field *acl;
210
211 va_list ap;
212 va_start(ap, format);
213 ret = acl_parse_format(context, &acl, format, ap);
214 va_end(ap);
215 if(ret)
216 return ret;
217
218 found = acl_match_acl(context, acl, string);
219 acl_free_list(acl, !found);
220 if (found) {
221 return 0;
222 } else {
223 krb5_set_error_message(context, EACCES, N_("ACL did not match", ""));
224 return EACCES;
225 }
226 }
227
228 /**
229 * krb5_acl_match_file matches ACL format against each line in a file
230 * using krb5_acl_match_string(). Lines starting with # are treated
231 * like comments and ignored.
232 *
233 * @param context Kerberos 5 context.
234 * @param file file with acl listed in the file.
235 * @param format format to match.
236 * @param ... parameter to format string.
237 *
238 * @return Return an error code or 0.
239 *
240 * @sa krb5_acl_match_string
241 * @ingroup krb5_support
242 */
243
244 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_acl_match_file(krb5_context context,const char * file,const char * format,...)245 krb5_acl_match_file(krb5_context context,
246 const char *file,
247 const char *format,
248 ...)
249 {
250 krb5_error_code ret;
251 struct acl_field *acl = NULL;
252 char buf[256];
253 va_list ap;
254 FILE *f;
255 krb5_boolean found;
256
257 f = fopen(file, "r");
258 if(f == NULL) {
259 int save_errno = errno;
260 rk_strerror_r(save_errno, buf, sizeof(buf));
261 krb5_set_error_message(context, save_errno,
262 N_("open(%s): %s", "file, errno"),
263 file, buf);
264 return save_errno;
265 }
266 rk_cloexec_file(f);
267
268 va_start(ap, format);
269 ret = acl_parse_format(context, &acl, format, ap);
270 va_end(ap);
271 if(ret) {
272 fclose(f);
273 return ret;
274 }
275
276 found = FALSE;
277 while(fgets(buf, sizeof(buf), f)) {
278 if(buf[0] == '#')
279 continue;
280 if(acl_match_acl(context, acl, buf)) {
281 found = TRUE;
282 break;
283 }
284 free_retv(acl);
285 }
286
287 fclose(f);
288 acl_free_list(acl, !found);
289 if (found) {
290 return 0;
291 } else {
292 krb5_set_error_message(context, EACCES, N_("ACL did not match", ""));
293 return EACCES;
294 }
295 }
296