1 | /* vi: set sw=4 ts=4: */
|
---|
2 | /*
|
---|
3 | * CRONTAB
|
---|
4 | *
|
---|
5 | * usually setuid root, -c option only works if getuid() == geteuid()
|
---|
6 | *
|
---|
7 | * Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
|
---|
8 | * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
|
---|
9 | *
|
---|
10 | * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
|
---|
11 | */
|
---|
12 |
|
---|
13 | #include "busybox.h"
|
---|
14 | #include <stdio.h>
|
---|
15 | #include <stdlib.h>
|
---|
16 | #include <stdarg.h>
|
---|
17 | #include <string.h>
|
---|
18 | #include <errno.h>
|
---|
19 | #include <time.h>
|
---|
20 | #include <dirent.h>
|
---|
21 | #include <fcntl.h>
|
---|
22 | #include <unistd.h>
|
---|
23 | #include <syslog.h>
|
---|
24 | #include <signal.h>
|
---|
25 | #include <getopt.h>
|
---|
26 | #include <sys/ioctl.h>
|
---|
27 | #include <sys/wait.h>
|
---|
28 | #include <sys/stat.h>
|
---|
29 | #include <sys/resource.h>
|
---|
30 |
|
---|
31 | #ifndef CRONTABS
|
---|
32 | #define CRONTABS "/var/spool/cron/crontabs"
|
---|
33 | #endif
|
---|
34 | #ifndef TMPDIR
|
---|
35 | #define TMPDIR "/var/spool/cron"
|
---|
36 | #endif
|
---|
37 | #ifndef CRONUPDATE
|
---|
38 | #define CRONUPDATE "cron.update"
|
---|
39 | #endif
|
---|
40 | #ifndef PATH_VI
|
---|
41 | #define PATH_VI "/bin/vi" /* location of vi */
|
---|
42 | #endif
|
---|
43 |
|
---|
44 | static const char *CDir = CRONTABS;
|
---|
45 |
|
---|
46 | static void EditFile(const char *user, const char *file);
|
---|
47 | static int GetReplaceStream(const char *user, const char *file);
|
---|
48 | static int ChangeUser(const char *user, short dochdir);
|
---|
49 |
|
---|
50 | int
|
---|
51 | crontab_main(int ac, char **av)
|
---|
52 | {
|
---|
53 | enum { NONE, EDIT, LIST, REPLACE, DELETE } option = NONE;
|
---|
54 | const struct passwd *pas;
|
---|
55 | const char *repFile = NULL;
|
---|
56 | int repFd = 0;
|
---|
57 | int i;
|
---|
58 | char caller[256]; /* user that ran program */
|
---|
59 | int UserId;
|
---|
60 |
|
---|
61 | UserId = getuid();
|
---|
62 | if ((pas = getpwuid(UserId)) == NULL)
|
---|
63 | bb_perror_msg_and_die("getpwuid");
|
---|
64 |
|
---|
65 | safe_strncpy(caller, pas->pw_name, sizeof(caller));
|
---|
66 |
|
---|
67 | i = 1;
|
---|
68 | if (ac > 1) {
|
---|
69 | if (av[1][0] == '-' && av[1][1] == 0) {
|
---|
70 | option = REPLACE;
|
---|
71 | ++i;
|
---|
72 | } else if (av[1][0] != '-') {
|
---|
73 | option = REPLACE;
|
---|
74 | ++i;
|
---|
75 | repFile = av[1];
|
---|
76 | }
|
---|
77 | }
|
---|
78 |
|
---|
79 | for (; i < ac; ++i) {
|
---|
80 | char *ptr = av[i];
|
---|
81 |
|
---|
82 | if (*ptr != '-')
|
---|
83 | break;
|
---|
84 | ptr += 2;
|
---|
85 |
|
---|
86 | switch(ptr[-1]) {
|
---|
87 | case 'l':
|
---|
88 | if (ptr[-1] == 'l')
|
---|
89 | option = LIST;
|
---|
90 | /* fall through */
|
---|
91 | case 'e':
|
---|
92 | if (ptr[-1] == 'e')
|
---|
93 | option = EDIT;
|
---|
94 | /* fall through */
|
---|
95 | case 'd':
|
---|
96 | if (ptr[-1] == 'd')
|
---|
97 | option = DELETE;
|
---|
98 | /* fall through */
|
---|
99 | case 'u':
|
---|
100 | if (i + 1 < ac && av[i+1][0] != '-') {
|
---|
101 | ++i;
|
---|
102 | if (getuid() == geteuid()) {
|
---|
103 | pas = getpwnam(av[i]);
|
---|
104 | if (pas) {
|
---|
105 | UserId = pas->pw_uid;
|
---|
106 | } else {
|
---|
107 | bb_error_msg_and_die("user %s unknown", av[i]);
|
---|
108 | }
|
---|
109 | } else {
|
---|
110 | bb_error_msg_and_die("only the superuser may specify a user");
|
---|
111 | }
|
---|
112 | }
|
---|
113 | break;
|
---|
114 | case 'c':
|
---|
115 | if (getuid() == geteuid()) {
|
---|
116 | CDir = (*ptr) ? ptr : av[++i];
|
---|
117 | } else {
|
---|
118 | bb_error_msg_and_die("-c option: superuser only");
|
---|
119 | }
|
---|
120 | break;
|
---|
121 | default:
|
---|
122 | i = ac;
|
---|
123 | break;
|
---|
124 | }
|
---|
125 | }
|
---|
126 | if (i != ac || option == NONE)
|
---|
127 | bb_show_usage();
|
---|
128 |
|
---|
129 | /*
|
---|
130 | * Get password entry
|
---|
131 | */
|
---|
132 |
|
---|
133 | if ((pas = getpwuid(UserId)) == NULL)
|
---|
134 | bb_perror_msg_and_die("getpwuid");
|
---|
135 |
|
---|
136 | /*
|
---|
137 | * If there is a replacement file, obtain a secure descriptor to it.
|
---|
138 | */
|
---|
139 |
|
---|
140 | if (repFile) {
|
---|
141 | repFd = GetReplaceStream(caller, repFile);
|
---|
142 | if (repFd < 0)
|
---|
143 | bb_error_msg_and_die("unable to read replacement file");
|
---|
144 | }
|
---|
145 |
|
---|
146 | /*
|
---|
147 | * Change directory to our crontab directory
|
---|
148 | */
|
---|
149 |
|
---|
150 | bb_xchdir(CDir);
|
---|
151 |
|
---|
152 | /*
|
---|
153 | * Handle options as appropriate
|
---|
154 | */
|
---|
155 |
|
---|
156 | switch(option) {
|
---|
157 | case LIST:
|
---|
158 | {
|
---|
159 | FILE *fi;
|
---|
160 | char buf[1024];
|
---|
161 |
|
---|
162 | if ((fi = fopen(pas->pw_name, "r"))) {
|
---|
163 | while (fgets(buf, sizeof(buf), fi) != NULL)
|
---|
164 | fputs(buf, stdout);
|
---|
165 | fclose(fi);
|
---|
166 | } else {
|
---|
167 | bb_error_msg("no crontab for %s", pas->pw_name);
|
---|
168 | }
|
---|
169 | }
|
---|
170 | break;
|
---|
171 | case EDIT:
|
---|
172 | {
|
---|
173 | FILE *fi;
|
---|
174 | int fd;
|
---|
175 | int n;
|
---|
176 | char tmp[128];
|
---|
177 | char buf[1024];
|
---|
178 |
|
---|
179 | snprintf(tmp, sizeof(tmp), TMPDIR "/crontab.%d", getpid());
|
---|
180 | fd = bb_xopen3(tmp, O_RDWR|O_CREAT|O_TRUNC|O_EXCL, 0600);
|
---|
181 | chown(tmp, getuid(), getgid());
|
---|
182 | if ((fi = fopen(pas->pw_name, "r"))) {
|
---|
183 | while ((n = fread(buf, 1, sizeof(buf), fi)) > 0)
|
---|
184 | write(fd, buf, n);
|
---|
185 | }
|
---|
186 | EditFile(caller, tmp);
|
---|
187 | remove(tmp);
|
---|
188 | lseek(fd, 0L, 0);
|
---|
189 | repFd = fd;
|
---|
190 | }
|
---|
191 | option = REPLACE;
|
---|
192 | /* fall through */
|
---|
193 | case REPLACE:
|
---|
194 | {
|
---|
195 | char buf[1024];
|
---|
196 | char path[1024];
|
---|
197 | int fd;
|
---|
198 | int n;
|
---|
199 |
|
---|
200 | snprintf(path, sizeof(path), "%s.new", pas->pw_name);
|
---|
201 | if ((fd = open(path, O_CREAT|O_TRUNC|O_APPEND|O_WRONLY, 0600)) >= 0) {
|
---|
202 | while ((n = read(repFd, buf, sizeof(buf))) > 0) {
|
---|
203 | write(fd, buf, n);
|
---|
204 | }
|
---|
205 | close(fd);
|
---|
206 | rename(path, pas->pw_name);
|
---|
207 | } else {
|
---|
208 | bb_error_msg("unable to create %s/%s", CDir, path);
|
---|
209 | }
|
---|
210 | close(repFd);
|
---|
211 | }
|
---|
212 | break;
|
---|
213 | case DELETE:
|
---|
214 | remove(pas->pw_name);
|
---|
215 | break;
|
---|
216 | case NONE:
|
---|
217 | default:
|
---|
218 | break;
|
---|
219 | }
|
---|
220 |
|
---|
221 | /*
|
---|
222 | * Bump notification file. Handle window where crond picks file up
|
---|
223 | * before we can write our entry out.
|
---|
224 | */
|
---|
225 |
|
---|
226 | if (option == REPLACE || option == DELETE) {
|
---|
227 | FILE *fo;
|
---|
228 | struct stat st;
|
---|
229 |
|
---|
230 | while ((fo = fopen(CRONUPDATE, "a"))) {
|
---|
231 | fprintf(fo, "%s\n", pas->pw_name);
|
---|
232 | fflush(fo);
|
---|
233 | if (fstat(fileno(fo), &st) != 0 || st.st_nlink != 0) {
|
---|
234 | fclose(fo);
|
---|
235 | break;
|
---|
236 | }
|
---|
237 | fclose(fo);
|
---|
238 | /* loop */
|
---|
239 | }
|
---|
240 | if (fo == NULL) {
|
---|
241 | bb_error_msg("unable to append to %s/%s", CDir, CRONUPDATE);
|
---|
242 | }
|
---|
243 | }
|
---|
244 | return 0;
|
---|
245 | }
|
---|
246 |
|
---|
247 | static int
|
---|
248 | GetReplaceStream(const char *user, const char *file)
|
---|
249 | {
|
---|
250 | int filedes[2];
|
---|
251 | int pid;
|
---|
252 | int fd;
|
---|
253 | int n;
|
---|
254 | char buf[1024];
|
---|
255 |
|
---|
256 | if (pipe(filedes) < 0) {
|
---|
257 | perror("pipe");
|
---|
258 | return(-1);
|
---|
259 | }
|
---|
260 | if ((pid = fork()) < 0) {
|
---|
261 | perror("fork");
|
---|
262 | return(-1);
|
---|
263 | }
|
---|
264 | if (pid > 0) {
|
---|
265 | /*
|
---|
266 | * PARENT
|
---|
267 | */
|
---|
268 |
|
---|
269 | close(filedes[1]);
|
---|
270 | if (read(filedes[0], buf, 1) != 1) {
|
---|
271 | close(filedes[0]);
|
---|
272 | filedes[0] = -1;
|
---|
273 | }
|
---|
274 | return(filedes[0]);
|
---|
275 | }
|
---|
276 |
|
---|
277 | /*
|
---|
278 | * CHILD
|
---|
279 | */
|
---|
280 |
|
---|
281 | close(filedes[0]);
|
---|
282 |
|
---|
283 | if (ChangeUser(user, 0) < 0)
|
---|
284 | exit(0);
|
---|
285 |
|
---|
286 | bb_default_error_retval = 0;
|
---|
287 | fd = bb_xopen3(file, O_RDONLY, 0);
|
---|
288 | buf[0] = 0;
|
---|
289 | write(filedes[1], buf, 1);
|
---|
290 | while ((n = read(fd, buf, sizeof(buf))) > 0) {
|
---|
291 | write(filedes[1], buf, n);
|
---|
292 | }
|
---|
293 | exit(0);
|
---|
294 | }
|
---|
295 |
|
---|
296 | static void
|
---|
297 | EditFile(const char *user, const char *file)
|
---|
298 | {
|
---|
299 | int pid;
|
---|
300 |
|
---|
301 | if ((pid = fork()) == 0) {
|
---|
302 | /*
|
---|
303 | * CHILD - change user and run editor
|
---|
304 | */
|
---|
305 | char *ptr;
|
---|
306 | char visual[1024];
|
---|
307 |
|
---|
308 | if (ChangeUser(user, 1) < 0)
|
---|
309 | exit(0);
|
---|
310 | if ((ptr = getenv("VISUAL")) == NULL || strlen(ptr) > 256)
|
---|
311 | ptr = PATH_VI;
|
---|
312 |
|
---|
313 | snprintf(visual, sizeof(visual), "%s %s", ptr, file);
|
---|
314 | execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", visual, NULL);
|
---|
315 | perror("exec");
|
---|
316 | exit(0);
|
---|
317 | }
|
---|
318 | if (pid < 0) {
|
---|
319 | /*
|
---|
320 | * PARENT - failure
|
---|
321 | */
|
---|
322 | bb_perror_msg_and_die("fork");
|
---|
323 | }
|
---|
324 | wait4(pid, NULL, 0, NULL);
|
---|
325 | }
|
---|
326 |
|
---|
327 | static int
|
---|
328 | ChangeUser(const char *user, short dochdir)
|
---|
329 | {
|
---|
330 | struct passwd *pas;
|
---|
331 |
|
---|
332 | /*
|
---|
333 | * Obtain password entry and change privileges
|
---|
334 | */
|
---|
335 |
|
---|
336 | if ((pas = getpwnam(user)) == NULL) {
|
---|
337 | bb_perror_msg_and_die("failed to get uid for %s", user);
|
---|
338 | return(-1);
|
---|
339 | }
|
---|
340 | setenv("USER", pas->pw_name, 1);
|
---|
341 | setenv("HOME", pas->pw_dir, 1);
|
---|
342 | setenv("SHELL", DEFAULT_SHELL, 1);
|
---|
343 |
|
---|
344 | /*
|
---|
345 | * Change running state to the user in question
|
---|
346 | */
|
---|
347 | change_identity(pas);
|
---|
348 |
|
---|
349 | if (dochdir) {
|
---|
350 | if (chdir(pas->pw_dir) < 0) {
|
---|
351 | bb_perror_msg("chdir failed: %s %s", user, pas->pw_dir);
|
---|
352 | bb_xchdir(TMPDIR);
|
---|
353 | }
|
---|
354 | }
|
---|
355 | return(pas->pw_uid);
|
---|
356 | }
|
---|