1 /* vi: set sw=4 ts=4: */
5 * usually setuid root, -c option only works if getuid() == geteuid()
7 * Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
8 * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
10 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
16 #define CRONTABS "/var/spool/cron/crontabs"
19 #define CRONUPDATE "cron.update"
22 static void change_user(const struct passwd *pas)
24 xsetenv("USER", pas->pw_name);
25 xsetenv("HOME", pas->pw_dir);
26 xsetenv("SHELL", DEFAULT_SHELL);
28 /* initgroups, setgid, setuid */
31 if (chdir(pas->pw_dir) < 0) {
32 bb_perror_msg("chdir(%s) by %s failed",
33 pas->pw_dir, pas->pw_name);
38 static void edit_file(const struct passwd *pas, const char *file)
43 if (pid < 0) /* failure */
44 bb_perror_msg_and_die("vfork");
45 if (pid) { /* parent */
50 /* CHILD - change user and run editor */
52 ptr = getenv("VISUAL");
54 ptr = getenv("EDITOR");
59 BB_EXECLP(ptr, ptr, file, NULL);
60 bb_perror_msg_and_die("exec %s", ptr);
63 static int open_as_user(const struct passwd *pas, const char *file)
69 if (pid < 0) /* ERROR */
70 bb_perror_msg_and_die("vfork");
71 if (pid) { /* PARENT */
72 if (wait4pid(pid) == 0) {
73 /* exitcode 0: child says it can read */
74 return open(file, O_RDONLY);
80 /* initgroups, setgid, setuid */
82 /* 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);
87 int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
88 int crontab_main(int argc UNUSED_PARAM, char **argv)
90 const struct passwd *pas;
91 const char *crontab_dir = CRONTABS;
94 char *user_name; /* -u USER */
99 /* file [opts] Replace crontab from file
100 * - [opts] Replace crontab from stdin
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.
115 OPT_ler = OPT_l + OPT_e + OPT_r,
118 opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
119 opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
122 if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */
123 /* run by non-root? */
124 if (opt_ler & (OPT_u|OPT_c))
125 bb_error_msg_and_die("only root can use -c or -u");
128 if (opt_ler & OPT_u) {
129 pas = xgetpwnam(user_name);
131 pas = xgetpwuid(getuid());
134 #define user_name DONT_USE_ME_BEYOND_THIS_POINT
136 /* From now on, keep only -l, -e, -r bits */
138 if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
141 /* Read replacement file under user's UID/GID/group vector */
142 src_fd = STDIN_FILENO;
143 if (!opt_ler) { /* Replace? */
146 if (NOT_LONE_DASH(argv[0])) {
147 src_fd = open_as_user(pas, argv[0]);
149 bb_error_msg_and_die("user %s cannot read %s",
150 pas->pw_name, argv[0]);
154 /* cd to our crontab directory */
159 /* Handle requested operation */
162 default: /* case OPT_r: Delete */
163 unlink(pas->pw_name);
166 case OPT_l: /* List */
168 char *args[2] = { pas->pw_name, NULL };
171 * the rest go play with cron update file */
174 case OPT_e: /* Edit */
175 tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid());
176 /* No O_EXCL: we don't want to be stuck if earlier crontabs
177 * were killed, leaving stale temp file behind */
178 src_fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
179 fchown(src_fd, pas->pw_uid, pas->pw_gid);
180 fd = open(pas->pw_name, O_RDONLY);
182 bb_copyfd_eof(fd, src_fd);
184 xlseek(src_fd, 0, SEEK_SET);
186 close_on_exec_on(src_fd); /* don't want editor to see this fd */
187 edit_file(pas, tmp_fname);
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);
194 bb_copyfd_eof(src_fd, fd);
196 xrename(new_fname, pas->pw_name);
198 bb_error_msg("cannot create %s/%s",
199 crontab_dir, new_fname);
208 /* Bump notification file. Handle window where crond picks file up
209 * before we can write our entry out.
211 while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
214 fdprintf(fd, "%s\n", pas->pw_name);
215 if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
220 * file was deleted, maybe crond missed our notification */
225 bb_error_msg("cannot append to %s/%s",
226 crontab_dir, CRONUPDATE);