Contents of /tags/mkinitrd-6_2_0/busybox/miscutils/crontab.c
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Sun May 30 11:54:28 2010 UTC (14 years, 4 months ago) by niro
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Sun May 30 11:54:28 2010 UTC (14 years, 4 months ago) by niro
File MIME type: text/plain
File size: 5516 byte(s)
tagged 'mkinitrd-6_2_0'
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 "libbb.h" |
14 | |
15 | #define CRONTABS CONFIG_FEATURE_CROND_DIR "/crontabs" |
16 | #ifndef CRONUPDATE |
17 | #define CRONUPDATE "cron.update" |
18 | #endif |
19 | |
20 | static void change_user(const struct passwd *pas) |
21 | { |
22 | xsetenv("USER", pas->pw_name); |
23 | xsetenv("HOME", pas->pw_dir); |
24 | xsetenv("SHELL", DEFAULT_SHELL); |
25 | |
26 | /* initgroups, setgid, setuid */ |
27 | change_identity(pas); |
28 | |
29 | if (chdir(pas->pw_dir) < 0) { |
30 | bb_perror_msg("chdir(%s) by %s failed", |
31 | pas->pw_dir, pas->pw_name); |
32 | xchdir("/tmp"); |
33 | } |
34 | } |
35 | |
36 | static void edit_file(const struct passwd *pas, const char *file) |
37 | { |
38 | const char *ptr; |
39 | int pid = vfork(); |
40 | |
41 | if (pid < 0) /* failure */ |
42 | bb_perror_msg_and_die("vfork"); |
43 | if (pid) { /* parent */ |
44 | wait4pid(pid); |
45 | return; |
46 | } |
47 | |
48 | /* CHILD - change user and run editor */ |
49 | change_user(pas); |
50 | ptr = getenv("VISUAL"); |
51 | if (!ptr) { |
52 | ptr = getenv("EDITOR"); |
53 | if (!ptr) |
54 | ptr = "vi"; |
55 | } |
56 | |
57 | BB_EXECLP(ptr, ptr, file, NULL); |
58 | bb_perror_msg_and_die("exec %s", ptr); |
59 | } |
60 | |
61 | static int open_as_user(const struct passwd *pas, const char *file) |
62 | { |
63 | pid_t pid; |
64 | char c; |
65 | |
66 | pid = vfork(); |
67 | if (pid < 0) /* ERROR */ |
68 | bb_perror_msg_and_die("vfork"); |
69 | if (pid) { /* PARENT */ |
70 | if (wait4pid(pid) == 0) { |
71 | /* exitcode 0: child says it can read */ |
72 | return open(file, O_RDONLY); |
73 | } |
74 | return -1; |
75 | } |
76 | |
77 | /* CHILD */ |
78 | /* initgroups, setgid, setuid */ |
79 | change_identity(pas); |
80 | /* We just try to read one byte. If it works, file is readable |
81 | * under this user. We signal that by exiting with 0. */ |
82 | _exit(safe_read(xopen(file, O_RDONLY), &c, 1) < 0); |
83 | } |
84 | |
85 | int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
86 | int crontab_main(int argc UNUSED_PARAM, char **argv) |
87 | { |
88 | const struct passwd *pas; |
89 | const char *crontab_dir = CRONTABS; |
90 | char *tmp_fname; |
91 | char *new_fname; |
92 | char *user_name; /* -u USER */ |
93 | int fd; |
94 | int src_fd; |
95 | int opt_ler; |
96 | |
97 | /* file [opts] Replace crontab from file |
98 | * - [opts] Replace crontab from stdin |
99 | * -u user User |
100 | * -c dir Crontab directory |
101 | * -l List crontab for user |
102 | * -e Edit crontab for user |
103 | * -r Delete crontab for user |
104 | * bbox also supports -d == -r, but most other crontab |
105 | * implementations do not. Deprecated. |
106 | */ |
107 | enum { |
108 | OPT_u = (1 << 0), |
109 | OPT_c = (1 << 1), |
110 | OPT_l = (1 << 2), |
111 | OPT_e = (1 << 3), |
112 | OPT_r = (1 << 4), |
113 | OPT_ler = OPT_l + OPT_e + OPT_r, |
114 | }; |
115 | |
116 | opt_complementary = "?1:dr"; /* max one argument; -d implies -r */ |
117 | opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir); |
118 | argv += optind; |
119 | |
120 | if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */ |
121 | /* Run by non-root */ |
122 | if (opt_ler & (OPT_u|OPT_c)) |
123 | bb_error_msg_and_die(bb_msg_you_must_be_root); |
124 | } |
125 | |
126 | if (opt_ler & OPT_u) { |
127 | pas = xgetpwnam(user_name); |
128 | } else { |
129 | pas = xgetpwuid(getuid()); |
130 | } |
131 | |
132 | #define user_name DONT_USE_ME_BEYOND_THIS_POINT |
133 | |
134 | /* From now on, keep only -l, -e, -r bits */ |
135 | opt_ler &= OPT_ler; |
136 | if ((opt_ler - 1) & opt_ler) /* more than one bit set? */ |
137 | bb_show_usage(); |
138 | |
139 | /* Read replacement file under user's UID/GID/group vector */ |
140 | src_fd = STDIN_FILENO; |
141 | if (!opt_ler) { /* Replace? */ |
142 | if (!argv[0]) |
143 | bb_show_usage(); |
144 | if (NOT_LONE_DASH(argv[0])) { |
145 | src_fd = open_as_user(pas, argv[0]); |
146 | if (src_fd < 0) |
147 | bb_error_msg_and_die("user %s cannot read %s", |
148 | pas->pw_name, argv[0]); |
149 | } |
150 | } |
151 | |
152 | /* cd to our crontab directory */ |
153 | xchdir(crontab_dir); |
154 | |
155 | tmp_fname = NULL; |
156 | |
157 | /* Handle requested operation */ |
158 | switch (opt_ler) { |
159 | |
160 | default: /* case OPT_r: Delete */ |
161 | unlink(pas->pw_name); |
162 | break; |
163 | |
164 | case OPT_l: /* List */ |
165 | { |
166 | char *args[2] = { pas->pw_name, NULL }; |
167 | return bb_cat(args); |
168 | /* list exits, |
169 | * the rest go play with cron update file */ |
170 | } |
171 | |
172 | case OPT_e: /* Edit */ |
173 | tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid()); |
174 | /* No O_EXCL: we don't want to be stuck if earlier crontabs |
175 | * were killed, leaving stale temp file behind */ |
176 | src_fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600); |
177 | fchown(src_fd, pas->pw_uid, pas->pw_gid); |
178 | fd = open(pas->pw_name, O_RDONLY); |
179 | if (fd >= 0) { |
180 | bb_copyfd_eof(fd, src_fd); |
181 | close(fd); |
182 | xlseek(src_fd, 0, SEEK_SET); |
183 | } |
184 | close_on_exec_on(src_fd); /* don't want editor to see this fd */ |
185 | edit_file(pas, tmp_fname); |
186 | /* fall through */ |
187 | |
188 | case 0: /* Replace (no -l, -e, or -r were given) */ |
189 | new_fname = xasprintf("%s.new", pas->pw_name); |
190 | fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600); |
191 | if (fd >= 0) { |
192 | bb_copyfd_eof(src_fd, fd); |
193 | close(fd); |
194 | xrename(new_fname, pas->pw_name); |
195 | } else { |
196 | bb_error_msg("can't create %s/%s", |
197 | crontab_dir, new_fname); |
198 | } |
199 | if (tmp_fname) |
200 | unlink(tmp_fname); |
201 | /*free(tmp_fname);*/ |
202 | /*free(new_fname);*/ |
203 | |
204 | } /* switch */ |
205 | |
206 | /* Bump notification file. Handle window where crond picks file up |
207 | * before we can write our entry out. |
208 | */ |
209 | while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) { |
210 | struct stat st; |
211 | |
212 | fdprintf(fd, "%s\n", pas->pw_name); |
213 | if (fstat(fd, &st) != 0 || st.st_nlink != 0) { |
214 | /*close(fd);*/ |
215 | break; |
216 | } |
217 | /* st.st_nlink == 0: |
218 | * file was deleted, maybe crond missed our notification */ |
219 | close(fd); |
220 | /* loop */ |
221 | } |
222 | if (fd < 0) { |
223 | bb_error_msg("can't append to %s/%s", |
224 | crontab_dir, CRONUPDATE); |
225 | } |
226 | return 0; |
227 | } |