blob: 13dfd77ad18ce42df0186d27fb3a2d6e2ca8846a [file] [log] [blame]
Bernhard Reutner-Fischerd9cf7ac2006-04-12 18:39:58 +00001/* vi: set sw=4 ts=4: */
Eric Andersenf6f7bfb2002-10-22 12:24:59 +00002/*
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)
Mike Frysingerf284c762006-04-16 20:38:26 +00008 * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
Eric Andersenf6f7bfb2002-10-22 12:24:59 +00009 *
Mike Frysingerf284c762006-04-16 20:38:26 +000010 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
Eric Andersenf6f7bfb2002-10-22 12:24:59 +000011 */
12
Denis Vlasenkob6adbf12007-05-26 19:00:18 +000013#include "libbb.h"
Eric Andersenf6f7bfb2002-10-22 12:24:59 +000014
15#ifndef CRONTABS
16#define CRONTABS "/var/spool/cron/crontabs"
17#endif
Eric Andersenf6f7bfb2002-10-22 12:24:59 +000018#ifndef CRONUPDATE
19#define CRONUPDATE "cron.update"
20#endif
Eric Andersenf6f7bfb2002-10-22 12:24:59 +000021
Denis Vlasenko069e3472008-02-16 13:17:13 +000022static void change_user(const struct passwd *pas)
Eric Andersenf6f7bfb2002-10-22 12:24:59 +000023{
Denis Vlasenkob8d1a4c2008-09-20 16:28:59 +000024 xsetenv("USER", pas->pw_name);
25 xsetenv("HOME", pas->pw_dir);
26 xsetenv("SHELL", DEFAULT_SHELL);
Denis Vlasenko94d5d822006-09-27 19:48:56 +000027
Denis Vlasenko069e3472008-02-16 13:17:13 +000028 /* initgroups, setgid, setuid */
Denis Vlasenko94d5d822006-09-27 19:48:56 +000029 change_identity(pas);
30
Denis Vlasenko069e3472008-02-16 13:17:13 +000031 if (chdir(pas->pw_dir) < 0) {
32 bb_perror_msg("chdir(%s) by %s failed",
33 pas->pw_dir, pas->pw_name);
Denis Vlasenko7fc294c2008-02-16 13:47:57 +000034 xchdir("/tmp");
Denis Vlasenko069e3472008-02-16 13:17:13 +000035 }
36}
37
38static void edit_file(const struct passwd *pas, const char *file)
39{
40 const char *ptr;
Denis Vlasenko82604e92008-07-01 15:59:42 +000041 int pid = vfork();
Denis Vlasenko069e3472008-02-16 13:17:13 +000042
Denis Vlasenko82604e92008-07-01 15:59:42 +000043 if (pid < 0) /* failure */
44 bb_perror_msg_and_die("vfork");
Denis Vlasenko069e3472008-02-16 13:17:13 +000045 if (pid) { /* parent */
46 wait4pid(pid);
47 return;
48 }
49
50 /* CHILD - change user and run editor */
51 change_user(pas);
52 ptr = getenv("VISUAL");
53 if (!ptr) {
54 ptr = getenv("EDITOR");
55 if (!ptr)
Denis Vlasenkob44c7902008-03-17 09:29:43 +000056 ptr = "vi";
Denis Vlasenko069e3472008-02-16 13:17:13 +000057 }
58
Denis Vlasenko7fc294c2008-02-16 13:47:57 +000059 BB_EXECLP(ptr, ptr, file, NULL);
Denis Vlasenko069e3472008-02-16 13:17:13 +000060 bb_perror_msg_and_die("exec %s", ptr);
61}
62
63static int open_as_user(const struct passwd *pas, const char *file)
64{
Denis Vlasenko069e3472008-02-16 13:17:13 +000065 pid_t pid;
66 char c;
67
Denis Vlasenko82604e92008-07-01 15:59:42 +000068 pid = vfork();
69 if (pid < 0) /* ERROR */
70 bb_perror_msg_and_die("vfork");
Denis Vlasenko069e3472008-02-16 13:17:13 +000071 if (pid) { /* PARENT */
Denis Vlasenko03b4c142008-02-17 14:30:03 +000072 if (wait4pid(pid) == 0) {
73 /* exitcode 0: child says it can read */
Denis Vlasenko069e3472008-02-16 13:17:13 +000074 return open(file, O_RDONLY);
Denis Vlasenko03b4c142008-02-17 14:30:03 +000075 }
Denis Vlasenko069e3472008-02-16 13:17:13 +000076 return -1;
77 }
78
79 /* CHILD */
Denis Vlasenko069e3472008-02-16 13:17:13 +000080 /* initgroups, setgid, setuid */
81 change_identity(pas);
Denis Vlasenko03b4c142008-02-17 14:30:03 +000082 /* We just try to read one byte. If it works, file is readable
83 * under this user. We signal that by exiting with 0. */
84 _exit(safe_read(xopen(file, O_RDONLY), &c, 1) < 0);
Denis Vlasenko069e3472008-02-16 13:17:13 +000085}
86
87int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
Denis Vlasenkoa60f84e2008-07-05 09:18:54 +000088int crontab_main(int argc UNUSED_PARAM, char **argv)
Denis Vlasenko069e3472008-02-16 13:17:13 +000089{
90 const struct passwd *pas;
91 const char *crontab_dir = CRONTABS;
92 char *tmp_fname;
93 char *new_fname;
94 char *user_name; /* -u USER */
95 int fd;
Denis Vlasenko30cfdf92008-09-21 15:29:29 +000096 int src_fd;
Denis Vlasenko069e3472008-02-16 13:17:13 +000097 int opt_ler;
Denis Vlasenko069e3472008-02-16 13:17:13 +000098
99 /* file [opts] Replace crontab from file
100 * - [opts] Replace crontab from stdin
101 * -u user User
102 * -c dir Crontab directory
103 * -l List crontab for user
104 * -e Edit crontab for user
105 * -r Delete crontab for user
106 * bbox also supports -d == -r, but most other crontab
107 * implementations do not. Deprecated.
108 */
109 enum {
110 OPT_u = (1 << 0),
111 OPT_c = (1 << 1),
112 OPT_l = (1 << 2),
113 OPT_e = (1 << 3),
114 OPT_r = (1 << 4),
115 OPT_ler = OPT_l + OPT_e + OPT_r,
116 };
117
Denis Vlasenko069e3472008-02-16 13:17:13 +0000118 opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
119 opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
120 argv += optind;
121
Denis Vlasenkoc9ca0a32008-02-18 11:08:33 +0000122 if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */
123 /* run by non-root? */
Denis Vlasenko7fc294c2008-02-16 13:47:57 +0000124 if (opt_ler & (OPT_u|OPT_c))
Denis Vlasenko069e3472008-02-16 13:17:13 +0000125 bb_error_msg_and_die("only root can use -c or -u");
Denis Vlasenko7fc294c2008-02-16 13:47:57 +0000126 }
Denis Vlasenko069e3472008-02-16 13:17:13 +0000127
128 if (opt_ler & OPT_u) {
Denis Vlasenkod7a805e2008-12-03 19:05:55 +0000129 pas = xgetpwnam(user_name);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000130 } else {
Denis Vlasenko0c68a872008-12-02 22:56:59 +0000131 pas = xgetpwuid(getuid());
Denis Vlasenko069e3472008-02-16 13:17:13 +0000132 }
133
134#define user_name DONT_USE_ME_BEYOND_THIS_POINT
Denis Vlasenko069e3472008-02-16 13:17:13 +0000135
136 /* From now on, keep only -l, -e, -r bits */
137 opt_ler &= OPT_ler;
138 if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
139 bb_show_usage();
140
141 /* Read replacement file under user's UID/GID/group vector */
Denis Vlasenko30cfdf92008-09-21 15:29:29 +0000142 src_fd = STDIN_FILENO;
Denis Vlasenko069e3472008-02-16 13:17:13 +0000143 if (!opt_ler) { /* Replace? */
144 if (!argv[0])
145 bb_show_usage();
146 if (NOT_LONE_DASH(argv[0])) {
Denis Vlasenko30cfdf92008-09-21 15:29:29 +0000147 src_fd = open_as_user(pas, argv[0]);
148 if (src_fd < 0)
Denis Vlasenko069e3472008-02-16 13:17:13 +0000149 bb_error_msg_and_die("user %s cannot read %s",
150 pas->pw_name, argv[0]);
Denis Vlasenko94d5d822006-09-27 19:48:56 +0000151 }
152 }
Denis Vlasenko069e3472008-02-16 13:17:13 +0000153
154 /* cd to our crontab directory */
155 xchdir(crontab_dir);
156
157 tmp_fname = NULL;
158
159 /* Handle requested operation */
160 switch (opt_ler) {
161
162 default: /* case OPT_r: Delete */
Denis Vlasenko03b4c142008-02-17 14:30:03 +0000163 unlink(pas->pw_name);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000164 break;
165
166 case OPT_l: /* List */
167 {
168 char *args[2] = { pas->pw_name, NULL };
169 return bb_cat(args);
170 /* list exits,
171 * the rest go play with cron update file */
172 }
173
174 case OPT_e: /* Edit */
Denis Vlasenko7fc294c2008-02-16 13:47:57 +0000175 tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid());
Denis Vlasenkob44c7902008-03-17 09:29:43 +0000176 /* No O_EXCL: we don't want to be stuck if earlier crontabs
177 * were killed, leaving stale temp file behind */
Denis Vlasenko30cfdf92008-09-21 15:29:29 +0000178 src_fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
179 fchown(src_fd, pas->pw_uid, pas->pw_gid);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000180 fd = open(pas->pw_name, O_RDONLY);
181 if (fd >= 0) {
Denis Vlasenko30cfdf92008-09-21 15:29:29 +0000182 bb_copyfd_eof(fd, src_fd);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000183 close(fd);
Denis Vlasenko30cfdf92008-09-21 15:29:29 +0000184 xlseek(src_fd, 0, SEEK_SET);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000185 }
Denis Vlasenko30cfdf92008-09-21 15:29:29 +0000186 close_on_exec_on(src_fd); /* don't want editor to see this fd */
Denis Vlasenko069e3472008-02-16 13:17:13 +0000187 edit_file(pas, tmp_fname);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000188 /* fall through */
189
190 case 0: /* Replace (no -l, -e, or -r were given) */
191 new_fname = xasprintf("%s.new", pas->pw_name);
192 fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600);
193 if (fd >= 0) {
Denis Vlasenko30cfdf92008-09-21 15:29:29 +0000194 bb_copyfd_eof(src_fd, fd);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000195 close(fd);
Denis Vlasenko03b4c142008-02-17 14:30:03 +0000196 xrename(new_fname, pas->pw_name);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000197 } else {
198 bb_error_msg("cannot create %s/%s",
199 crontab_dir, new_fname);
200 }
201 if (tmp_fname)
Denis Vlasenko03b4c142008-02-17 14:30:03 +0000202 unlink(tmp_fname);
Denis Vlasenko069e3472008-02-16 13:17:13 +0000203 /*free(tmp_fname);*/
204 /*free(new_fname);*/
205
206 } /* switch */
207
208 /* Bump notification file. Handle window where crond picks file up
209 * before we can write our entry out.
210 */
Bernhard Reutner-Fischer27dd4952008-02-18 18:35:53 +0000211 while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
Denis Vlasenko069e3472008-02-16 13:17:13 +0000212 struct stat st;
213
214 fdprintf(fd, "%s\n", pas->pw_name);
215 if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
216 /*close(fd);*/
217 break;
218 }
219 /* st.st_nlink == 0:
220 * file was deleted, maybe crond missed our notification */
221 close(fd);
222 /* loop */
223 }
224 if (fd < 0) {
225 bb_error_msg("cannot append to %s/%s",
226 crontab_dir, CRONUPDATE);
227 }
228 return 0;
Eric Andersenf6f7bfb2002-10-22 12:24:59 +0000229}