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 status = setgid (gid);
182 if (status != 0)
183 {
184 ERROR ("exec plugin: setgid (%i) failed: %s",
185 gid, sstrerror (errno, errbuf, sizeof (errbuf)));
186 exit (-1);
187 }
189 if (egid != -1)
190 {
191 status = setegid (egid);
192 if (status != 0)
193 {
194 ERROR ("exec plugin: setegid (%i) failed: %s",
195 egid, sstrerror (errno, errbuf, sizeof (errbuf)));
196 exit (-1);
197 }
198 }
200 status = setuid (uid);
201 if (status != 0)
202 {
203 ERROR ("exec plugin: setuid (%i) failed: %s",
204 uid, sstrerror (errno, errbuf, sizeof (errbuf)));
205 exit (-1);
206 }
208 arg0 = strrchr (pl->exec, '/');
209 if (arg0 != NULL)
210 arg0++;
211 if ((arg0 == NULL) || (*arg0 == '\0'))
212 arg0 = pl->exec;
214 status = execlp (pl->exec, arg0, (char *) 0);
216 ERROR ("exec plugin: exec failed: %s",
217 sstrerror (errno, errbuf, sizeof (errbuf)));
218 exit (-1);
219 } /* void exec_child */
221 static int fork_child (program_list_t *pl)
222 {
223 int fd_pipe[2];
224 int status;
226 if (pl->pid != 0)
227 return (-1);
229 status = pipe (fd_pipe);
230 if (status != 0)
231 {
232 char errbuf[1024];
233 ERROR ("exec plugin: pipe failed: %s",
234 sstrerror (errno, errbuf, sizeof (errbuf)));
235 return (-1);
236 }
238 pl->pid = fork ();
239 if (pl->pid < 0)
240 {
241 char errbuf[1024];
242 ERROR ("exec plugin: fork failed: %s",
243 sstrerror (errno, errbuf, sizeof (errbuf)));
244 return (-1);
245 }
246 else if (pl->pid == 0)
247 {
248 close (fd_pipe[0]);
250 /* Connect the pipe to STDOUT and STDERR */
251 if (fd_pipe[1] != STDOUT_FILENO)
252 dup2 (fd_pipe[1], STDOUT_FILENO);
253 if (fd_pipe[1] != STDERR_FILENO)
254 dup2 (fd_pipe[1], STDERR_FILENO);
255 if ((fd_pipe[1] != STDOUT_FILENO) && (fd_pipe[1] != STDERR_FILENO))
256 close (fd_pipe[1]);
258 exec_child (pl);
259 /* does not return */
260 }
262 close (fd_pipe[1]);
263 return (fd_pipe[0]);
264 } /* int fork_child */
266 static int parse_line (char *buffer)
267 {
268 char *fields[256];
269 int fields_num;
271 fields[0] = "PUTVAL";
272 fields_num = strsplit (buffer, &fields[1], STATIC_ARRAY_SIZE(fields) - 1);
274 handle_putval (stdout, fields, fields_num + 1);
275 return (0);
276 } /* int parse_line */
278 static void *exec_read_one (void *arg)
279 {
280 program_list_t *pl = (program_list_t *) arg;
281 int fd;
282 FILE *fh;
283 char buffer[1024];
285 fd = fork_child (pl);
286 if (fd < 0)
287 pthread_exit ((void *) 1);
289 assert (pl->pid != 0);
291 fh = fdopen (fd, "r");
292 if (fh == NULL)
293 {
294 char errbuf[1024];
295 ERROR ("exec plugin: fdopen (%i) failed: %s", fd,
296 sstrerror (errno, errbuf, sizeof (errbuf)));
297 kill (pl->pid, SIGTERM);
298 close (fd);
299 pthread_exit ((void *) 1);
300 }
302 while (fgets (buffer, sizeof (buffer), fh) != NULL)
303 {
304 int len;
306 len = strlen (buffer);
308 /* Remove newline from end. */
309 while ((len > 0) && ((buffer[len - 1] == '\n')
310 || (buffer[len - 1] == '\r')))
311 buffer[--len] = '\0';
313 DEBUG ("exec plugin: exec_read_one: buffer = %s", buffer);
315 parse_line (buffer);
316 } /* while (fgets) */
318 fclose (fh);
319 pl->pid = 0;
321 pthread_exit ((void *) 0);
322 return (NULL);
323 } /* void *exec_read_one */
325 static int exec_read (void)
326 {
327 program_list_t *pl;
329 for (pl = pl_head; pl != NULL; pl = pl->next)
330 {
331 pthread_t t;
332 pthread_attr_t attr;
334 if (pl->pid != 0)
335 continue;
337 pthread_attr_init (&attr);
338 pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
339 pthread_create (&t, &attr, exec_read_one, (void *) pl);
340 } /* for (pl) */
342 return (0);
343 } /* int exec_read */
345 static int exec_shutdown (void)
346 {
347 program_list_t *pl;
348 program_list_t *next;
350 pl = pl_head;
351 while (pl != NULL)
352 {
353 next = pl->next;
355 if (pl->pid > 0)
356 {
357 kill (pl->pid, SIGTERM);
358 INFO ("exec plugin: Sent SIGTERM to %hu", (unsigned short int) pl->pid);
359 }
361 sfree (pl->user);
362 sfree (pl);
364 pl = next;
365 } /* while (pl) */
366 pl_head = NULL;
368 return (0);
369 } /* int exec_shutdown */
371 void module_register (void)
372 {
373 plugin_register_config ("exec", exec_config, config_keys, config_keys_num);
374 plugin_register_read ("exec", exec_read);
375 plugin_register_shutdown ("exec", exec_shutdown);
376 } /* void module_register */
378 /*
379 * vim:shiftwidth=2:softtabstop=2:tabstop=8
380 */