check and warn about capabilities misconfiguration

[collectd.git] / src / exec.c

diff --git a/src/exec.c b/src/exec.c
index 0445b14..c51465b 100644 (file)
--- a/src/exec.c
+++ b/src/exec.c
@@ -18,14 +18,16 @@
  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  *
  * Authors:
- *   Florian octo Forster <octo at verplant.org>
+ *   Florian octo Forster <octo at collectd.org>
  *   Sebastian Harl <sh at tokkee.org>
  *   Peter Holik <peter at holik.at>
  **/
 
+#define _DEFAULT_SOURCE
 #define _BSD_SOURCE /* For setgroups */
 
 #include "collectd.h"
+
 #include "common.h"
 #include "plugin.h"
 
@@ -37,7 +39,9 @@
 #include <grp.h>
 #include <signal.h>
 
-#include <pthread.h>
+#ifdef HAVE_SYS_CAPABILITY_H
+# include <sys/capability.h>
+#endif
 
 #define PL_NORMAL        0x01
 #define PL_NOTIF_ACTION  0x02
@@ -125,13 +129,12 @@ static int exec_config_exec (oconfig_item_t *ci) /* {{{ */
     return (-1);
   }
 
-  pl = (program_list_t *) malloc (sizeof (program_list_t));
+  pl = calloc (1, sizeof (*pl));
   if (pl == NULL)
   {
-    ERROR ("exec plugin: malloc failed.");
+    ERROR ("exec plugin: calloc failed.");
     return (-1);
   }
-  memset (pl, '\0', sizeof (program_list_t));
 
   if (strcasecmp ("NotificationExec", ci->key) == 0)
     pl->flags |= PL_NOTIF_ACTION;
@@ -162,16 +165,15 @@ static int exec_config_exec (oconfig_item_t *ci) /* {{{ */
     return (-1);
   }
 
-  pl->argv = (char **) malloc (ci->values_num * sizeof (char *));
+  pl->argv = calloc (ci->values_num, sizeof (*pl->argv));
   if (pl->argv == NULL)
   {
-    ERROR ("exec plugin: malloc failed.");
+    ERROR ("exec plugin: calloc failed.");
     sfree (pl->exec);
     sfree (pl->user);
     sfree (pl);
     return (-1);
   }
-  memset (pl->argv, '\0', ci->values_num * sizeof (char *));
 
   {
     char *tmp = strrchr (ci->values[1].value.string, '/');
@@ -183,7 +185,7 @@ static int exec_config_exec (oconfig_item_t *ci) /* {{{ */
   pl->argv[0] = strdup (buffer);
   if (pl->argv[0] == NULL)
   {
-    ERROR ("exec plugin: malloc failed.");
+    ERROR ("exec plugin: strdup failed.");
     sfree (pl->argv);
     sfree (pl->exec);
     sfree (pl->user);
@@ -248,9 +250,7 @@ static int exec_config_exec (oconfig_item_t *ci) /* {{{ */
 
 static int exec_config (oconfig_item_t *ci) /* {{{ */
 {
-  int i;
-
-  for (i = 0; i < ci->children_num; i++)
+  for (int i = 0; i < ci->children_num; i++)
   {
     oconfig_item_t *child = ci->children + i;
     if ((strcasecmp ("Exec", child->key) == 0)
@@ -349,7 +349,6 @@ static void reset_signal_mask (void) /* {{{ */
 {
   sigset_t ss;
 
-  memset (&ss, 0, sizeof (ss));
   sigemptyset (&ss);
   sigprocmask (SIG_SETMASK, &ss, /* old mask = */ NULL);
 } /* }}} void reset_signal_mask */
@@ -474,11 +473,10 @@ static int fork_child (program_list_t *pl, int *fd_in, int *fd_out, int *fd_err)
   else if (pid == 0)
   {
     int fd_num;
-    int fd;
 
     /* Close all file descriptors but the pipe end we need. */
     fd_num = getdtablesize ();
-    for (fd = 0; fd < fd_num; fd++)
+    for (int fd = 0; fd < fd_num; fd++)
     {
       if ((fd == fd_pipe_in[0])
           || (fd == fd_pipe_out[1])
@@ -724,7 +722,6 @@ static void *exec_notification_one (void *arg) /* {{{ */
 {
   program_list_t *pl = ((program_list_and_notification_t *) arg)->pl;
   notification_t *n = &((program_list_and_notification_t *) arg)->n;
-  notification_meta_t *meta;
   int fd;
   FILE *fh;
   int pid;
@@ -743,8 +740,7 @@ static void *exec_notification_one (void *arg) /* {{{ */
     char errbuf[1024];
     ERROR ("exec plugin: fdopen (%i) failed: %s", fd,
         sstrerror (errno, errbuf, sizeof (errbuf)));
-    kill (pl->pid, SIGTERM);
-    pl->pid = 0;
+    kill (pid, SIGTERM);
     close (fd);
     sfree (arg);
     pthread_exit ((void *) 1);
@@ -773,7 +769,7 @@ static void *exec_notification_one (void *arg) /* {{{ */
   if (strlen (n->type_instance) > 0)
     fprintf (fh, "TypeInstance: %s\n", n->type_instance);
 
-  for (meta = n->meta; meta != NULL; meta = meta->next)
+  for (notification_meta_t *meta = n->meta; meta != NULL; meta = meta->next)
   {
     if (meta->type == NM_TYPE_STRING)
       fprintf (fh, "%s: %s\n", meta->name, meta->nm_value.nm_string);
@@ -808,20 +804,34 @@ static void *exec_notification_one (void *arg) /* {{{ */
 
 static int exec_init (void) /* {{{ */
 {
-  struct sigaction sa;
+  struct sigaction sa = {
+    .sa_handler = sigchld_handler
+  };
 
-  memset (&sa, '\0', sizeof (sa));
-  sa.sa_handler = sigchld_handler;
   sigaction (SIGCHLD, &sa, NULL);
 
+#ifdef HAVE_SYS_CAPABILITY_H
+  if ((check_capability (CAP_SETUID) != 0) ||
+      (check_capability (CAP_SETGID) != 0))
+  {
+    if (getuid () == 0)
+      WARNING ("exec plugin: Running collectd as root, but the CAP_SETUID "
+          "or CAP_SETGID capabilities are missing. The plugin's read function "
+          "will probably fail. Is your init system dropping capabilities ?");
+    else
+      WARNING ("exec plugin: collectd doesn't have the CAP_SETUID or "
+          "CAP_SETGID capabilities. If you don't want to run collectd as root, "
+          "try running \"setcap 'cap_setuid=ep cap_setgid=ep'\" on the "
+          "collectd binary.");
+  }
+#endif
+
   return (0);
 } /* int exec_init }}} */
 
 static int exec_read (void) /* {{{ */
 {
-  program_list_t *pl;
-
-  for (pl = pl_head; pl != NULL; pl = pl->next)
+  for (program_list_t *pl = pl_head; pl != NULL; pl = pl->next)
   {
     pthread_t t;
     pthread_attr_t attr;
@@ -852,10 +862,9 @@ static int exec_read (void) /* {{{ */
 static int exec_notification (const notification_t *n, /* {{{ */
     user_data_t __attribute__((unused)) *user_data)
 {
-  program_list_t *pl;
   program_list_and_notification_t *pln;
 
-  for (pl = pl_head; pl != NULL; pl = pl->next)
+  for (program_list_t *pl = pl_head; pl != NULL; pl = pl->next)
   {
     pthread_t t;
     pthread_attr_t attr;
@@ -868,8 +877,7 @@ static int exec_notification (const notification_t *n, /* {{{ */
     if (pl->pid != 0)
       continue;
 
-    pln = (program_list_and_notification_t *) malloc (sizeof
-        (program_list_and_notification_t));
+    pln = malloc (sizeof (*pln));
     if (pln == NULL)
     {
       ERROR ("exec plugin: malloc failed.");