1 /**
2 * collectd - src/exec.c
3 * Copyright (C) 2007 Florian octo Forster
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the
7 * Free Software Foundation; only version 2 of the License is applicable.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
17 *
18 * Authors:
19 * Florian octo Forster <octo at verplant.org>
20 **/
22 #include "collectd.h"
23 #include "common.h"
24 #include "plugin.h"
25 #include "utils_cmd_putval.h"
27 #include <sys/types.h>
28 #include <pwd.h>
29 #include <grp.h>
30 #include <signal.h>
32 #include <pthread.h>
34 /*
35 * Private data types
36 */
37 struct program_list_s;
38 typedef struct program_list_s program_list_t;
39 struct program_list_s
40 {
41 char *user;
42 char *group;
43 char *exec;
44 int pid;
45 program_list_t *next;
46 };
48 /*
49 * Private variables
50 */
51 static const char *config_keys[] =
52 {
53 "Exec"
54 };
55 static int config_keys_num = STATIC_ARRAY_SIZE (config_keys);
57 static program_list_t *pl_head = NULL;
59 /*
60 * Functions
61 */
62 static int exec_config (const char *key, const char *value)
63 {
64 if (strcasecmp ("Exec", key) == 0)
65 {
66 program_list_t *pl;
67 pl = (program_list_t *) malloc (sizeof (program_list_t));
68 if (pl == NULL)
69 return (1);
70 memset (pl, '\0', sizeof (program_list_t));
72 pl->user = strdup (value);
73 if (pl->user == NULL)
74 {
75 sfree (pl);
76 return (1);
77 }
79 pl->exec = strchr (pl->user, ' ');
80 if (pl->exec == NULL)
81 {
82 sfree (pl->user);
83 sfree (pl);
84 return (1);
85 }
86 while (*pl->exec == ' ')
87 {
88 *pl->exec = '\0';
89 pl->exec++;
90 }
92 if (*pl->exec == '\0')
93 {
94 sfree (pl->user);
95 sfree (pl);
96 return (1);
97 }
99 pl->next = pl_head;
100 pl_head = pl;
102 pl->group = strchr (pl->user, ':');
103 if (NULL != pl->group) {
104 *pl->group = '\0';
105 pl->group++;
106 }
107 }
108 else
109 {
110 return (-1);
111 }
113 return (0);
114 } /* int exec_config */
116 static void exec_child (program_list_t *pl)
117 {
118 int status;
119 int uid;
120 int gid;
121 int egid;
122 char *arg0;
124 struct passwd *sp_ptr;
125 struct passwd sp;
126 char nambuf[2048];
127 char errbuf[1024];
129 sp_ptr = NULL;
130 status = getpwnam_r (pl->user, &sp, nambuf, sizeof (nambuf), &sp_ptr);
131 if (status != 0)
132 {
133 ERROR ("exec plugin: getpwnam_r failed: %s",
134 sstrerror (errno, errbuf, sizeof (errbuf)));
135 exit (-1);
136 }
137 if (sp_ptr == NULL)
138 {
139 ERROR ("exec plugin: No such user: `%s'", pl->user);
140 exit (-1);
141 }
143 uid = sp.pw_uid;
144 gid = sp.pw_gid;
145 if (uid == 0)
146 {
147 ERROR ("exec plugin: Cowardly refusing to exec program as root.");
148 exit (-1);
149 }
151 /* The group configured in the configfile is set as effective group, because
152 * this way the forked process can (re-)gain the user's primary group. */
153 egid = -1;
154 if (NULL != pl->group)
155 {
156 if ('\0' != *pl->group) {
157 struct group *gr_ptr = NULL;
158 struct group gr;
160 status = getgrnam_r (pl->group, &gr, nambuf, sizeof (nambuf), &gr_ptr);
161 if (0 != status)
162 {
163 ERROR ("exec plugin: getgrnam_r failed: %s",
164 sstrerror (errno, errbuf, sizeof (errbuf)));
165 exit (-1);
166 }
167 if (NULL == gr_ptr)
168 {
169 ERROR ("exec plugin: No such group: `%s'", pl->group);
170 exit (-1);
171 }
173 egid = gr.gr_gid;
174 }
175 else
176 {
177 egid = gid;
178 }
179 } /* if (pl->group == NULL) */
181 #if HAVE_SETGROUPS
182 if (getuid () == 0)
183 {
184 gid_t glist[2];
185 size_t glist_len;
187 glist[0] = gid;
188 glist_len = 1;
190 if (gid != egid)
191 {
192 glist[1] = egid;
193 glist_len = 2;
194 }
196 setgroups (glist_len, glist);
197 }
198 #endif /* HAVE_SETGROUPS */
200 status = setgid (gid);
201 if (status != 0)
202 {
203 ERROR ("exec plugin: setgid (%i) failed: %s",
204 gid, sstrerror (errno, errbuf, sizeof (errbuf)));
205 exit (-1);
206 }
208 if (egid != -1)
209 {
210 status = setegid (egid);
211 if (status != 0)
212 {
213 ERROR ("exec plugin: setegid (%i) failed: %s",
214 egid, sstrerror (errno, errbuf, sizeof (errbuf)));
215 exit (-1);
216 }
217 }
219 status = setuid (uid);
220 if (status != 0)
221 {
222 ERROR ("exec plugin: setuid (%i) failed: %s",
223 uid, sstrerror (errno, errbuf, sizeof (errbuf)));
224 exit (-1);
225 }
227 arg0 = strrchr (pl->exec, '/');
228 if (arg0 != NULL)
229 arg0++;
230 if ((arg0 == NULL) || (*arg0 == '\0'))
231 arg0 = pl->exec;
233 status = execlp (pl->exec, arg0, (char *) 0);
235 ERROR ("exec plugin: exec failed: %s",
236 sstrerror (errno, errbuf, sizeof (errbuf)));
237 exit (-1);
238 } /* void exec_child */
240 static int fork_child (program_list_t *pl)
241 {
242 int fd_pipe[2];
243 int status;
245 if (pl->pid != 0)
246 return (-1);
248 status = pipe (fd_pipe);
249 if (status != 0)
250 {
251 char errbuf[1024];
252 ERROR ("exec plugin: pipe failed: %s",
253 sstrerror (errno, errbuf, sizeof (errbuf)));
254 return (-1);
255 }
257 pl->pid = fork ();
258 if (pl->pid < 0)
259 {
260 char errbuf[1024];
261 ERROR ("exec plugin: fork failed: %s",
262 sstrerror (errno, errbuf, sizeof (errbuf)));
263 return (-1);
264 }
265 else if (pl->pid == 0)
266 {
267 close (fd_pipe[0]);
269 /* Connect the pipe to STDOUT and STDERR */
270 if (fd_pipe[1] != STDOUT_FILENO)
271 dup2 (fd_pipe[1], STDOUT_FILENO);
272 if (fd_pipe[1] != STDERR_FILENO)
273 dup2 (fd_pipe[1], STDERR_FILENO);
274 if ((fd_pipe[1] != STDOUT_FILENO) && (fd_pipe[1] != STDERR_FILENO))
275 close (fd_pipe[1]);
277 exec_child (pl);
278 /* does not return */
279 }
281 close (fd_pipe[1]);
282 return (fd_pipe[0]);
283 } /* int fork_child */
285 static int parse_line (char *buffer)
286 {
287 char *fields[256];
288 int fields_num;
290 fields[0] = "PUTVAL";
291 fields_num = strsplit (buffer, &fields[1], STATIC_ARRAY_SIZE(fields) - 1);
293 handle_putval (stdout, fields, fields_num + 1);
294 return (0);
295 } /* int parse_line */
297 static void *exec_read_one (void *arg)
298 {
299 program_list_t *pl = (program_list_t *) arg;
300 int fd;
301 FILE *fh;
302 char buffer[1024];
304 fd = fork_child (pl);
305 if (fd < 0)
306 pthread_exit ((void *) 1);
308 assert (pl->pid != 0);
310 fh = fdopen (fd, "r");
311 if (fh == NULL)
312 {
313 char errbuf[1024];
314 ERROR ("exec plugin: fdopen (%i) failed: %s", fd,
315 sstrerror (errno, errbuf, sizeof (errbuf)));
316 kill (pl->pid, SIGTERM);
317 pl->pid = 0;
318 close (fd);
319 pthread_exit ((void *) 1);
320 }
322 while (fgets (buffer, sizeof (buffer), fh) != NULL)
323 {
324 int len;
326 len = strlen (buffer);
328 /* Remove newline from end. */
329 while ((len > 0) && ((buffer[len - 1] == '\n')
330 || (buffer[len - 1] == '\r')))
331 buffer[--len] = '\0';
333 DEBUG ("exec plugin: exec_read_one: buffer = %s", buffer);
335 parse_line (buffer);
336 } /* while (fgets) */
338 fclose (fh);
339 pl->pid = 0;
341 pthread_exit ((void *) 0);
342 return (NULL);
343 } /* void *exec_read_one */
345 static int exec_read (void)
346 {
347 program_list_t *pl;
349 for (pl = pl_head; pl != NULL; pl = pl->next)
350 {
351 pthread_t t;
352 pthread_attr_t attr;
354 if (pl->pid != 0)
355 continue;
357 pthread_attr_init (&attr);
358 pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
359 pthread_create (&t, &attr, exec_read_one, (void *) pl);
360 } /* for (pl) */
362 return (0);
363 } /* int exec_read */
365 static int exec_shutdown (void)
366 {
367 program_list_t *pl;
368 program_list_t *next;
370 pl = pl_head;
371 while (pl != NULL)
372 {
373 next = pl->next;
375 if (pl->pid > 0)
376 {
377 kill (pl->pid, SIGTERM);
378 INFO ("exec plugin: Sent SIGTERM to %hu", (unsigned short int) pl->pid);
379 }
381 sfree (pl->user);
382 sfree (pl);
384 pl = next;
385 } /* while (pl) */
386 pl_head = NULL;
388 return (0);
389 } /* int exec_shutdown */
391 void module_register (void)
392 {
393 plugin_register_config ("exec", exec_config, config_keys, config_keys_num);
394 plugin_register_read ("exec", exec_read);
395 plugin_register_shutdown ("exec", exec_shutdown);
396 } /* void module_register */
398 /*
399 * vim:shiftwidth=2:softtabstop=2:tabstop=8
400 */