check and warn about capabilities misconfiguration

[collectd.git] / src / dns.c

diff --git a/src/dns.c b/src/dns.c
index 2c3a904..be6d0dc 100644 (file)
--- a/src/dns.c
+++ b/src/dns.c
@@ -25,6 +25,7 @@
 #define _BSD_SOURCE
 
 #include "collectd.h"
+
 #include "common.h"
 #include "plugin.h"
 #include "configfile.h"
@@ -34,6 +35,10 @@
 
 #include <pcap.h>
 
+#ifdef HAVE_SYS_CAPABILITY_H
+# include <sys/capability.h>
+#endif
+
 /*
  * Private data types
  */
@@ -210,7 +215,7 @@ static int dns_run_pcap_loop (void)
 {
        pcap_t *pcap_obj;
        char    pcap_error[PCAP_ERRBUF_SIZE];
-       struct  bpf_program fp;
+       struct  bpf_program fp = { 0 };
 
        int status;
 
@@ -237,7 +242,6 @@ static int dns_run_pcap_loop (void)
                return (PCAP_ERROR);
        }
 
-       memset (&fp, 0, sizeof (fp));
        status = pcap_compile (pcap_obj, &fp, "udp port 53", 1, 0);
        if (status < 0)
        {
@@ -347,6 +351,20 @@ static int dns_init (void)
 
        listen_thread_init = 1;
 
+#ifdef HAVE_SYS_CAPABILITY_H
+       if (check_capability (CAP_NET_RAW) != 0)
+       {
+               if (getuid () == 0)
+                       WARNING ("dns plugin: Running collectd as root, but the CAP_NET_RAW "
+                                       "capability is missing. The plugin's read function will probably "
+                                       "fail. Is your init system dropping capabilities ?");
+               else
+                       WARNING ("dns plugin: collectd doesn't have the CAP_NET_RAW capability. "
+                                       "If you don't want to run collectd as root, try running \"setcap "
+                                       "cap_net_raw=ep\" on the collectd binary.");
+       }
+#endif
+
        return (0);
 } /* int dns_init */
 
@@ -390,7 +408,6 @@ static int dns_read (void)
        unsigned int keys[T_MAX];
        unsigned int values[T_MAX];
        int len;
-       int i;
 
        counter_list_t *ptr;
 
@@ -412,7 +429,7 @@ static int dns_read (void)
        }
        pthread_mutex_unlock (&qtype_mutex);
 
-       for (i = 0; i < len; i++)
+       for (int i = 0; i < len; i++)
        {
                DEBUG ("dns plugin: qtype = %u; counter = %u;", keys[i], values[i]);
                submit_derive ("dns_qtype", qtype_str (keys[i]), values[i]);
@@ -428,7 +445,7 @@ static int dns_read (void)
        }
        pthread_mutex_unlock (&opcode_mutex);
 
-       for (i = 0; i < len; i++)
+       for (int i = 0; i < len; i++)
        {
                DEBUG ("dns plugin: opcode = %u; counter = %u;", keys[i], values[i]);
                submit_derive ("dns_opcode", opcode_str (keys[i]), values[i]);
@@ -444,7 +461,7 @@ static int dns_read (void)
        }
        pthread_mutex_unlock (&rcode_mutex);
 
-       for (i = 0; i < len; i++)
+       for (int i = 0; i < len; i++)
        {
                DEBUG ("dns plugin: rcode = %u; counter = %u;", keys[i], values[i]);
                submit_derive ("dns_rcode", rcode_str (keys[i]), values[i]);