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1 | /* |
2 | Execute a program with a restricted access token. | |
3 | ||
4 | Copyright (C) 2009 Christian Franke | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License along | |
17 | with this program; if not, write to the Free Software Foundation, Inc., | |
18 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
19 | ||
20 | You should have received a copy of the GNU General Public License | |
21 | along with this program. If not, see <http://www.gnu.org/licenses/>. | |
22 | */ | |
23 | ||
24 | #if HAVE_CONFIG_H | |
25 | #include "config.h" | |
26 | #endif | |
27 | #define WINVER 0x0500 // >= W2K | |
28 | #include "common.h" | |
29 | ||
30 | #include <grp.h> | |
31 | #include <regex.h> | |
32 | #include <sddl.h> | |
33 | #include <sys/cygwin.h> | |
34 | ||
35 | static const char * progname; | |
36 | ||
37 | static int | |
38 | usage () | |
39 | { | |
40 | printf ( | |
41 | "%s is part of cygutils version %s\n" | |
42 | "\n" | |
43 | "Execute COMMAND with a restricted access token\n" | |
44 | "\n" | |
45 | "Usage: %s [OPTIONS] COMMAND [ARG ...]\n" | |
46 | "\n" | |
47 | "Group options\n" | |
48 | " -l Disable local administrator group [default]\n" | |
49 | " (same as '-g S-1-5-32-544').\n" | |
50 | " -d Disable domain administrator group [default]\n" | |
51 | " (same as '-g S-1-5-21-.\\*-512').\n" | |
52 | " -g GROUP Disable group(s) GROUP.\n" | |
53 | " -G GROUP Disable all groups except group(s) GROUP.\n" | |
54 | " -r GROUP Add group(s) GROUP to restricted SIDs.\n" | |
55 | "\n" | |
56 | "Privilege options\n" | |
57 | " -m Delete most privileges [default]\n" | |
58 | " (same as '-P SeChangeNotifyPrivilege').\n" | |
59 | " -p PRIV Delete privilege PRIV.\n" | |
60 | " -P PRIV Delete all privilege except privilege PRIV.\n" | |
61 | "\n" | |
62 | "General options\n" | |
63 | " -h Print this help.\n" | |
64 | " -v Verbose output, lists groups and privileges changed.\n" | |
65 | " Repeat to list all groups and privileges.\n" | |
66 | "\n" | |
67 | "If no group or privilege option is specified, '-l -d -m' is the default.\n" | |
68 | "Options with GROUP and PRIV parameter may be specified more than once.\n" | |
69 | "GROUP may be specified as a SID, a regular expression matching SIDs\n" | |
70 | "(must start with 'S-'), a numeric group id, or a group name.\n" | |
71 | "PRIV name match is not case sensitive, prefix 'Se' and suffix 'Privilege'\n" | |
72 | "may be omitted.\n" | |
73 | "\n", | |
74 | progname, PACKAGE_VERSION, progname | |
75 | ); | |
76 | return 1; | |
77 | } | |
78 | ||
79 | static int | |
80 | usageerror (const char * msg) | |
81 | { | |
82 | fprintf(stderr, "%s: %s\n", progname, msg); | |
83 | return 1; | |
84 | } | |
85 | ||
86 | static int | |
87 | cygerror (const char * msg) | |
88 | { | |
89 | perror (msg); | |
90 | return 1; | |
91 | } | |
92 | ||
93 | static int | |
94 | winerror (const char * msg) | |
95 | { | |
96 | fprintf (stderr, "%s: error %u\n", msg, (unsigned)GetLastError()); | |
97 | return 1; | |
98 | } | |
99 | ||
100 | static bool | |
101 | is_strsid (const char * s) | |
102 | { | |
103 | return (!strncmp (s, "S-", 2) | |
104 | && strspn (s + 2, "-0123456789") == strlen (s) - 2); | |
105 | } | |
106 | ||
107 | static const char * | |
108 | group_to_strsid (const char * name) | |
109 | { | |
110 | if (is_strsid(name)) | |
111 | // String SID. | |
112 | return name; | |
113 | else if (!strncmp (name, "S-", 2)) | |
114 | // SID regex. | |
115 | { | |
116 | regex_t rex; | |
117 | if (regcomp (&rex, name, REG_EXTENDED)) | |
118 | { | |
119 | fprintf (stderr, "%s: invalid regex\n", name); | |
120 | return NULL; | |
121 | } | |
122 | regfree (&rex); | |
123 | return name; | |
124 | } | |
125 | else | |
126 | { | |
127 | // Cygwin group id or name. | |
128 | const struct group * g; | |
129 | if (strspn (name, "0123456789") == strlen (name)) | |
130 | g = getgrgid (atoi (name)); | |
131 | else | |
132 | g = getgrnam (name); | |
133 | if (!(g && !strncmp (g->gr_passwd, "S-", 2))) | |
134 | { | |
135 | fprintf (stderr, "%s: unknown group\n", name); | |
136 | return NULL; | |
137 | } | |
138 | return strdup (g->gr_passwd); // TODO: Never freed. | |
139 | } | |
140 | } | |
141 | ||
142 | static const struct group * | |
143 | strsid_to_group(const char * strsid) | |
144 | { | |
145 | setgrent (); | |
146 | while (const struct group * g = getgrent ()) | |
147 | if (!strcmp (strsid, g->gr_passwd)) | |
148 | return g; | |
149 | return NULL; | |
150 | } | |
151 | ||
152 | static bool | |
153 | match_strsid (const char * strsid, const char * pattern) | |
154 | { | |
155 | if (is_strsid (pattern)) | |
156 | return !strcmp (strsid, pattern); | |
157 | regex_t rex; | |
158 | if (regcomp (&rex, pattern, REG_EXTENDED)) | |
159 | return false; | |
160 | bool rc = false; | |
161 | regmatch_t m; | |
162 | if (!regexec (&rex, strsid, 1, &m, 0) | |
163 | && m.rm_so == 0 && m.rm_eo == (int) strlen (strsid)) | |
164 | rc = true; | |
165 | regfree (&rex); | |
166 | return rc; | |
167 | } | |
168 | ||
169 | static bool | |
170 | match_priv (const char * priv, const char * pattern) | |
171 | { | |
172 | if (!strcmpi (priv, pattern)) | |
173 | return true; | |
174 | char buf[strlen (pattern) + 16]; | |
175 | sprintf (buf, "Se%sPrivilege", pattern); | |
176 | return !strcmpi (priv, buf); | |
177 | } | |
178 | ||
179 | int | |
180 | main (int argc, char **argv) | |
181 | { | |
182 | progname = argv[0]; | |
183 | if (argc < 2) | |
184 | return usage (); | |
185 | ||
186 | // Parse options. | |
187 | const int max_groups = 100, max_privs = 100; | |
188 | const char * group_args[max_groups]; | |
189 | const char * restr_args[max_groups]; | |
190 | bool restr_used[max_groups] = {false, }; | |
191 | const char * priv_args[max_privs]; | |
192 | int num_group_args = 0; | |
193 | int num_restr_args = 0; | |
194 | int num_priv_args = 0; | |
195 | ||
196 | bool d_flag = false, l_flag = false; | |
197 | bool m_flag = false; | |
198 | bool g_flag = false, G_flag = false; | |
199 | bool p_flag = false, P_flag = false; | |
200 | bool r_flag = false; | |
201 | int verbose = 0; | |
202 | ||
203 | int opt; | |
204 | while ((opt = getopt(argc, argv, "dlhmvg:G:p:P:r:")) != EOF) | |
205 | { | |
206 | if (num_group_args >= max_groups | |
207 | || num_priv_args >= max_privs | |
208 | || num_restr_args >= max_groups) | |
209 | usageerror ("too many options"); | |
210 | switch (opt) | |
211 | { | |
212 | case 'd': | |
213 | d_flag = true; | |
214 | break; | |
215 | case 'l': | |
216 | l_flag = true; | |
217 | break; | |
218 | case 'm': | |
219 | m_flag = true; | |
220 | break; | |
221 | case 'g': | |
222 | g_flag = true; | |
223 | if (!(group_args[num_group_args++] = group_to_strsid(optarg))) | |
224 | return 1; | |
225 | break; | |
226 | case 'G': | |
227 | G_flag = true; | |
228 | if (!(group_args[num_group_args++] = group_to_strsid(optarg))) | |
229 | return 1; | |
230 | break; | |
231 | case 'r': | |
232 | r_flag = true; | |
233 | if (!(restr_args[num_restr_args++] = group_to_strsid(optarg))) | |
234 | return 1; | |
235 | break; | |
236 | case 'p': | |
237 | p_flag = true; | |
238 | priv_args[num_priv_args++] = optarg; | |
239 | break; | |
240 | case 'P': | |
241 | P_flag = true; | |
242 | priv_args[num_priv_args++] = optarg; | |
243 | break; | |
244 | case 'v': | |
245 | verbose++; | |
246 | break; | |
247 | case 'h': | |
248 | return usage (); | |
249 | case '?': | |
250 | fprintf (stderr, "Try -h for help\n"); | |
251 | return 1; | |
252 | } | |
253 | } | |
254 | ||
255 | if (optind >= argc) | |
256 | return usageerror ("missing COMMAND"); | |
257 | ||
258 | // Set defaults | |
259 | if (!(d_flag || l_flag || m_flag || g_flag | |
260 | || G_flag || p_flag || P_flag || r_flag)) | |
261 | d_flag = l_flag = m_flag = true; | |
262 | ||
263 | if (!G_flag) | |
264 | { | |
265 | g_flag = true; | |
266 | if (l_flag) | |
267 | group_args[num_group_args++] = "S-1-5-32-544"; | |
268 | if (d_flag) | |
269 | group_args[num_group_args++] = "S-1-5-21-.*-512"; | |
270 | } | |
271 | else if (l_flag || d_flag || g_flag) | |
272 | return usageerror ("'-G' cannot be used with '-l', '-d', '-g'"); | |
273 | ||
274 | if (!p_flag) | |
275 | { | |
276 | if (m_flag) | |
277 | priv_args[num_priv_args++] = SE_CHANGE_NOTIFY_NAME; | |
278 | else if (!P_flag) | |
279 | p_flag = true; | |
280 | } | |
281 | else if (m_flag || P_flag) | |
282 | return usageerror ("'-p' cannot be used with '-m', '-P'"); | |
283 | ||
284 | // Get token | |
285 | HANDLE proc_token; | |
286 | if(!OpenProcessToken (GetCurrentProcess (), TOKEN_ALL_ACCESS, &proc_token)) | |
287 | return winerror("OpenProcessToken"); | |
288 | ||
289 | // Get groups. | |
290 | char groups_buf[sizeof(DWORD) + max_groups * sizeof(SID_AND_ATTRIBUTES)]; | |
291 | TOKEN_GROUPS * groups = (TOKEN_GROUPS *)groups_buf; | |
292 | DWORD size = 0; | |
293 | if (!GetTokenInformation (proc_token, TokenGroups, groups, sizeof(groups_buf), &size)) | |
294 | return winerror ("GetTokenInformation"); | |
295 | ||
296 | // Collect SIDs of groups to disable / restrict. | |
297 | SID_AND_ATTRIBUTES sids_to_disable[max_groups]; | |
298 | SID_AND_ATTRIBUTES sids_to_restrict[max_groups]; | |
299 | int num_sids_to_disable = 0, num_sids_to_restrict = 0; | |
300 | ||
301 | for (DWORD i = 0; i < groups->GroupCount; i++) | |
302 | { | |
303 | const SID_AND_ATTRIBUTES & grp = groups->Groups[i]; | |
304 | char * strsid; | |
305 | if (!ConvertSidToStringSid (grp.Sid, &strsid)) | |
306 | return winerror ("ConvertSidToStringSid"); | |
307 | ||
308 | // Any match with group options ? | |
309 | bool disable_sid = false; | |
310 | for (int j = 0; j < num_group_args && !disable_sid; j++) | |
311 | if (match_strsid (strsid, group_args[j])) | |
312 | disable_sid = true; | |
313 | if (!g_flag) | |
314 | disable_sid = !disable_sid; | |
315 | ||
316 | bool restrict_sid = false; | |
317 | for (int j = 0; j < num_restr_args && !restrict_sid; j++) | |
318 | if (match_strsid (strsid, restr_args[j])) | |
319 | restrict_sid = restr_used[j] = true; | |
320 | ||
321 | // Ignore special SIDs. | |
322 | bool ignore_sid = false; | |
323 | if ((grp.Attributes | |
324 | & (SE_GROUP_USE_FOR_DENY_ONLY|SE_GROUP_LOGON_ID)) | |
325 | && (disable_sid || restrict_sid)) | |
326 | { | |
327 | disable_sid = restrict_sid = false; | |
328 | ignore_sid = true; | |
329 | } | |
330 | ||
331 | if (verbose && (verbose > 1 || (disable_sid || restrict_sid))) | |
332 | { | |
333 | // Print group info | |
334 | printf ("%c%c %s%s%s%s%s", | |
335 | (ignore_sid ? 'i' : disable_sid ? 'd' : ' '), | |
336 | (restrict_sid ? 'r' : ' '), strsid, | |
337 | (grp.Attributes & SE_GROUP_ENABLED | |
338 | ? " [enabled]" : ""), | |
339 | (grp.Attributes & SE_GROUP_ENABLED_BY_DEFAULT | |
340 | ? " [default]" : ""), | |
341 | (grp.Attributes & SE_GROUP_USE_FOR_DENY_ONLY | |
342 | ? " [deny_only]" : ""), | |
343 | (grp.Attributes & SE_GROUP_LOGON_ID | |
344 | ? " [logon_id]" : "")); | |
345 | const struct group * g = strsid_to_group (strsid); | |
346 | if (g) | |
347 | printf (" gid=%lu(%s)", g->gr_gid, g->gr_name); | |
348 | printf ("\n"); | |
349 | } | |
350 | ||
351 | LocalFree(strsid); | |
352 | ||
353 | if (disable_sid) | |
354 | { | |
355 | sids_to_disable[num_sids_to_disable].Sid = grp.Sid; | |
356 | sids_to_disable[num_sids_to_disable].Attributes = 0; | |
357 | num_sids_to_disable++; | |
358 | } | |
359 | if (restrict_sid) | |
360 | { | |
361 | sids_to_restrict[num_sids_to_restrict].Sid = grp.Sid; | |
362 | sids_to_restrict[num_sids_to_restrict].Attributes = 0; | |
363 | num_sids_to_restrict++; | |
364 | } | |
365 | } | |
366 | ||
367 | // Add restricted SIDs not matched above. | |
368 | for (int i = 0; i < num_restr_args; i++) | |
369 | { | |
370 | if (restr_used[i]) | |
371 | continue; | |
372 | const char * strsid = restr_args[i]; | |
373 | if (!is_strsid (strsid)) | |
374 | continue; | |
375 | PSID sid; // TODO: Never freed. | |
376 | if (!ConvertStringSidToSid ((char *) strsid, &sid)) | |
377 | return winerror ("ConvertStringSidToSid"); | |
378 | ||
379 | if (verbose) | |
380 | { | |
381 | printf ("r %s", strsid); | |
382 | const struct group * g = strsid_to_group (strsid); | |
383 | if (g) | |
384 | printf (" gid=%lu(%s)", g->gr_gid, g->gr_name); | |
385 | printf ("\n"); | |
386 | } | |
387 | ||
388 | sids_to_restrict[num_sids_to_restrict].Sid = sid; | |
389 | sids_to_restrict[num_sids_to_restrict].Attributes = 0; | |
390 | num_sids_to_restrict++; | |
391 | } | |
392 | ||
393 | // Get privileges. | |
394 | char privs_buf[sizeof(DWORD) + max_privs * sizeof(LUID_AND_ATTRIBUTES)]; | |
395 | TOKEN_PRIVILEGES * privs = (TOKEN_PRIVILEGES *)privs_buf; | |
396 | if (!GetTokenInformation (proc_token, TokenPrivileges, privs, sizeof(privs_buf), &size)) | |
397 | return winerror ("GetTokenInformation"); | |
398 | ||
399 | // Collect LUIDs of privileges to disable. | |
400 | LUID_AND_ATTRIBUTES privs_to_delete[max_privs]; | |
401 | int num_privs_to_delete = 0; | |
402 | ||
403 | for (DWORD i = 0; i < privs->PrivilegeCount; i++) | |
404 | { | |
405 | LUID_AND_ATTRIBUTES & priv = privs->Privileges[i]; | |
406 | char name[100]; | |
407 | size = sizeof(name); | |
408 | if (!LookupPrivilegeName (NULL, &priv.Luid, name, &size)) | |
409 | return winerror ("LookupPrivilegeName"); | |
410 | ||
411 | // Any match with privilege options ? | |
412 | bool delete_priv = false; | |
413 | for (int j = 0; j < num_priv_args && !delete_priv; j++) | |
414 | if (match_priv (name, priv_args[j])) | |
415 | delete_priv = true; | |
416 | if (!p_flag) | |
417 | delete_priv = !delete_priv; | |
418 | ||
419 | if (verbose && (verbose > 1 || delete_priv)) | |
420 | printf("%c %s%s%s\n", (delete_priv ? 'd' : ' '), name, | |
421 | (priv.Attributes & SE_PRIVILEGE_ENABLED | |
422 | ? " [enabled]" : ""), | |
423 | (priv.Attributes & SE_PRIVILEGE_ENABLED_BY_DEFAULT | |
424 | ? " [default]" : "")); | |
425 | ||
426 | if (delete_priv) | |
427 | { | |
428 | privs_to_delete[num_privs_to_delete].Luid = priv.Luid; | |
429 | privs_to_delete[num_privs_to_delete].Attributes = 0; | |
430 | num_privs_to_delete++; | |
431 | } | |
432 | } | |
433 | ||
434 | // Create restricted token. | |
435 | HANDLE restr_token; | |
436 | if (!CreateRestrictedToken (proc_token, 0, | |
437 | num_sids_to_disable, sids_to_disable, | |
438 | num_privs_to_delete, privs_to_delete, | |
439 | num_sids_to_restrict, sids_to_restrict, | |
440 | &restr_token)) | |
441 | return winerror("CreateRestrictedToken"); | |
442 | ||
443 | CloseHandle (proc_token); | |
444 | ||
445 | // Change to restricted token. | |
446 | if (cygwin_internal (CW_SET_EXTERNAL_TOKEN, restr_token, CW_TOKEN_RESTRICTED)) | |
447 | return cygerror ("cygwin_internal (CW_SET_EXTERNAL_TOKEN, ...)"); | |
448 | ||
449 | if (setuid (geteuid ())) | |
450 | return cygerror ("setuid"); | |
451 | ||
452 | // exec command. | |
453 | if (verbose) | |
454 | { | |
455 | printf ("\nexec "); | |
456 | for (int i = optind; i < argc-1; i++) | |
457 | printf ("'%s' ", argv[i]); | |
458 | printf ("'%s'\n", argv[argc-1]); | |
459 | } | |
460 | ||
461 | execvp (argv[optind], argv + optind); | |
462 | ||
463 | return cygerror (argv[optind]); | |
464 | } |