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 setenv("USER", pas->pw_name, 1);
25 setenv("HOME", pas->pw_dir, 1);
26 setenv("SHELL", DEFAULT_SHELL, 1);
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) { /* parent */
48 /* CHILD - change user and run editor */
50 ptr = getenv("VISUAL");
52 ptr = getenv("EDITOR");
57 BB_EXECLP(ptr, ptr, file, NULL);
58 bb_perror_msg_and_die("exec %s", ptr);
61 static int open_as_user(const struct passwd *pas, const char *file)
67 if (pid) { /* PARENT */
68 if (wait4pid(pid) == 0) {
69 /* exitcode 0: child says it can read */
70 return open(file, O_RDONLY);
76 /* initgroups, setgid, setuid */
78 /* We just try to read one byte. If it works, file is readable
79 * under this user. We signal that by exiting with 0. */
80 _exit(safe_read(xopen(file, O_RDONLY), &c, 1) < 0);
83 int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
84 int crontab_main(int argc ATTRIBUTE_UNUSED, char **argv)
86 const struct passwd *pas;
87 const char *crontab_dir = CRONTABS;
90 char *user_name; /* -u USER */
94 /* file [opts] Replace crontab from file
95 * - [opts] Replace crontab from stdin
97 * -c dir Crontab directory
98 * -l List crontab for user
99 * -e Edit crontab for user
100 * -r Delete crontab for user
101 * bbox also supports -d == -r, but most other crontab
102 * implementations do not. Deprecated.
110 OPT_ler = OPT_l + OPT_e + OPT_r,
113 opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
114 opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
117 if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */
118 /* run by non-root? */
119 if (opt_ler & (OPT_u|OPT_c))
120 bb_error_msg_and_die("only root can use -c or -u");
123 if (opt_ler & OPT_u) {
124 pas = getpwnam(user_name);
126 bb_error_msg_and_die("user %s is not known", user_name);
128 uid_t my_uid = getuid();
129 pas = getpwuid(my_uid);
131 bb_perror_msg_and_die("no user record for UID %u",
135 #define user_name DONT_USE_ME_BEYOND_THIS_POINT
137 /* From now on, keep only -l, -e, -r bits */
139 if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
142 /* Read replacement file under user's UID/GID/group vector */
143 if (!opt_ler) { /* Replace? */
146 if (NOT_LONE_DASH(argv[0])) {
147 fd = open_as_user(pas, argv[0]);
149 bb_error_msg_and_die("user %s cannot read %s",
150 pas->pw_name, argv[0]);
151 xmove_fd(fd, STDIN_FILENO);
155 /* cd to our crontab directory */
160 /* Handle requested operation */
163 default: /* case OPT_r: Delete */
164 unlink(pas->pw_name);
167 case OPT_l: /* List */
169 char *args[2] = { pas->pw_name, NULL };
172 * the rest go play with cron update file */
175 case OPT_e: /* Edit */
176 tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid());
177 /* No O_EXCL: we don't want to be stuck if earlier crontabs
178 * were killed, leaving stale temp file behind */
179 fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
180 xmove_fd(fd, STDIN_FILENO);
181 fchown(STDIN_FILENO, pas->pw_uid, pas->pw_gid);
182 fd = open(pas->pw_name, O_RDONLY);
184 bb_copyfd_eof(fd, STDIN_FILENO);
187 edit_file(pas, tmp_fname);
188 xlseek(STDIN_FILENO, 0, SEEK_SET);
191 case 0: /* Replace (no -l, -e, or -r were given) */
192 new_fname = xasprintf("%s.new", pas->pw_name);
193 fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600);
195 bb_copyfd_eof(STDIN_FILENO, fd);
197 xrename(new_fname, pas->pw_name);
199 bb_error_msg("cannot create %s/%s",
200 crontab_dir, new_fname);
209 /* Bump notification file. Handle window where crond picks file up
210 * before we can write our entry out.
212 while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
215 fdprintf(fd, "%s\n", pas->pw_name);
216 if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
221 * file was deleted, maybe crond missed our notification */
226 bb_error_msg("cannot append to %s/%s",
227 crontab_dir, CRONUPDATE);