X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=src%2Fexec.c;h=e0d1f890441c7eff7c099c55d435907aa4f708bc;hb=92b269e2d433759066c621f7cf4d34bbc1ce78e8;hp=28380ac33677788acd1ffc2b4058ba08a9661e53;hpb=01d23e3f5daf016d03f82d92a76be2fe3decdca4;p=collectd.git

diff --git a/src/exec.c b/src/exec.c
index 28380ac3..e0d1f890 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -78,6 +78,11 @@ typedef struct program_list_and_notification_s {
 } program_list_and_notification_t;
 
 /*
+ * constants
+ */
+const long int MAX_GRBUF_SIZE = 65536;
+
+/*
  * Private variables
  */
 static program_list_t *pl_head = NULL;
@@ -348,6 +353,67 @@ static void close_pipe(int fd_pipe[2]) /* {{{ */
 } /* }}} void close_pipe */
 
 /*
+ * Get effective group ID from group name.
+ * Input arguments:
+ *       pl  :program list struct with group name
+ *       gid :group id to fallback in case egid cannot be determined.
+ * Returns:
+ *       egid effective group id if successfull,
+ *            -1 if group is not defined/not found.
+ *            -2 for any buffer allocation error.
+ */
+static int getegr_id(program_list_t *pl, int gid) /* {{{ */
+{
+  if (pl->group == NULL) {
+    return -1;
+  }
+  if (strcmp(pl->group, "") == 0) {
+    return gid;
+  }
+  struct group *gr_ptr = NULL;
+  struct group gr;
+
+  long int grbuf_size = sysconf(_SC_GETGR_R_SIZE_MAX);
+  if (grbuf_size <= 0)
+    grbuf_size = sysconf(_SC_PAGESIZE);
+  if (grbuf_size <= 0)
+    grbuf_size = 4096;
+
+  char *temp = NULL;
+  char *grbuf = NULL;
+
+  do {
+    temp = realloc(grbuf, grbuf_size);
+    if (temp == NULL) {
+      ERROR("exec plugin: getegr_id for %s: realloc buffer[%ld] failed ",
+            pl->group, grbuf_size);
+      sfree(grbuf);
+      return -2;
+    }
+    grbuf = temp;
+    if (getgrnam_r(pl->group, &gr, grbuf, grbuf_size, &gr_ptr) == 0) {
+      sfree(grbuf);
+      if (gr_ptr == NULL) {
+        ERROR("exec plugin: No such group: `%s'", pl->group);
+        return -1;
+      }
+      return gr.gr_gid;
+    } else if (errno == ERANGE) {
+      grbuf_size += grbuf_size; // increment buffer size and try again
+    } else {
+      char errbuf[1024];
+      ERROR("exec plugin: getegr_id failed %s",
+            sstrerror(errno, errbuf, sizeof(errbuf)));
+      sfree(grbuf);
+      return -2;
+    }
+  } while (grbuf_size <= MAX_GRBUF_SIZE);
+  ERROR("exec plugin: getegr_id Max grbuf size reached  for %s", pl->group);
+  sfree(grbuf);
+  return -2;
+} /* }}} */
+
+/*
  * Creates three pipes (one for reading, one for writing and one for errors),
  * forks a child, sets up the pipes so that fd_in is connected to STDIN of
  * the child and fd_out is connected to STDOUT and fd_err is connected to STDERR
@@ -369,11 +435,17 @@ static int fork_child(program_list_t *pl, int *fd_in, int *fd_out,
 
   struct passwd *sp_ptr;
   struct passwd sp;
-  char nambuf[4096];
 
   if (pl->pid != 0)
     return (-1);
 
+  long int nambuf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
+  if (nambuf_size <= 0)
+    nambuf_size = sysconf(_SC_PAGESIZE);
+  if (nambuf_size <= 0)
+    nambuf_size = 4096;
+  char nambuf[nambuf_size];
+
   if ((create_pipe(fd_pipe_in) == -1) || (create_pipe(fd_pipe_out) == -1) ||
       (create_pipe(fd_pipe_err) == -1))
     goto failed;
@@ -398,31 +470,10 @@ static int fork_child(program_list_t *pl, int *fd_in, int *fd_out,
     goto failed;
   }
 
-  /* The group configured in the configfile is set as effective group, because
-   * this way the forked process can (re-)gain the user's primary group. */
-  egid = -1;
-  if (NULL != pl->group) {
-    if ('\0' != *pl->group) {
-      struct group *gr_ptr = NULL;
-      struct group gr;
-
-      status = getgrnam_r(pl->group, &gr, nambuf, sizeof(nambuf), &gr_ptr);
-      if (0 != status) {
-        ERROR("exec plugin: Failed to get group information "
-              "for group ``%s'': %s",
-              pl->group, sstrerror(status, errbuf, sizeof(errbuf)));
-        goto failed;
-      }
-      if (NULL == gr_ptr) {
-        ERROR("exec plugin: No such group: `%s'", pl->group);
-        goto failed;
-      }
-
-      egid = gr.gr_gid;
-    } else {
-      egid = gid;
-    }
-  } /* if (pl->group == NULL) */
+  egid = getegr_id(pl, gid);
+  if (egid == -2) {
+    goto failed;
+  }
 
   pid = fork();
   if (pid < 0) {
@@ -787,7 +838,11 @@ static int exec_read(void) /* {{{ */
 
     pthread_attr_init(&attr);
     pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
-    plugin_thread_create(&t, &attr, exec_read_one, (void *)pl, "exec read");
+    int status =
+        plugin_thread_create(&t, &attr, exec_read_one, (void *)pl, "exec read");
+    if (status != 0) {
+      ERROR("exec plugin: plugin_thread_create failed.");
+    }
     pthread_attr_destroy(&attr);
   } /* for (pl) */
 
@@ -826,8 +881,11 @@ static int exec_notification(const notification_t *n, /* {{{ */
 
     pthread_attr_init(&attr);
     pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
-    plugin_thread_create(&t, &attr, exec_notification_one, (void *)pln,
-                         "exec notify");
+    int status = plugin_thread_create(&t, &attr, exec_notification_one,
+                                      (void *)pln, "exec notify");
+    if (status != 0) {
+      ERROR("exec plugin: plugin_thread_create failed.");
+    }
     pthread_attr_destroy(&attr);
   } /* for (pl) */