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Message-Id: <1472062105-17995-1-git-send-email-hannes@stressinduktion.org>
Date: Wed, 24 Aug 2016 20:08:25 +0200
From: Hannes Frederic Sowa <hannes@...essinduktion.org>
To: netdev@...r.kernel.org
Subject: [PATCH iproute] iptuntap: show processes using tuntap interface
Show which processes are using which tun/tap devices, e.g.:
$ ip -d tuntap
tun0: tun
Attached to processes: vpnc(9531)
vnet0: tap vnet_hdr
Attached to processes: qemu-system-x86(10442)
virbr0-nic: tap UNKNOWN_FLAGS:800
Attached to processes:
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
ip/iptuntap.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 109 insertions(+)
diff --git a/ip/iptuntap.c b/ip/iptuntap.c
index 43774f96e335ef..b5aa0542c1f8f2 100644
--- a/ip/iptuntap.c
+++ b/ip/iptuntap.c
@@ -25,6 +25,7 @@
#include <fcntl.h>
#include <dirent.h>
#include <errno.h>
+#include <glob.h>
#include "rt_names.h"
#include "utils.h"
@@ -273,6 +274,109 @@ static void print_flags(long flags)
printf(" UNKNOWN_FLAGS:%lx", flags);
}
+static char *pid_name(pid_t pid)
+{
+ char *comm;
+ FILE *f;
+ int err;
+
+ err = asprintf(&comm, "/proc/%d/comm", pid);
+ if (err < 0)
+ return NULL;
+
+ f = fopen(comm, "r");
+ free(comm);
+ if (!f) {
+ perror("fopen");
+ return NULL;
+ }
+
+ if (fscanf(f, "%ms\n", &comm) != 1) {
+ perror("fscanf");
+ comm = NULL;
+ }
+
+
+ if (fclose(f))
+ perror("fclose");
+
+ return comm;
+}
+
+static void show_processes(const char *name)
+{
+ glob_t globbuf = { };
+ char **fd_path;
+ int err;
+
+ err = glob("/proc/[0-9]*/fd/[0-9]*", GLOB_NOSORT,
+ NULL, &globbuf);
+ if (err)
+ return;
+
+ fd_path = globbuf.gl_pathv;
+ while (*fd_path) {
+ const char *dev_net_tun = "/dev/net/tun";
+ const size_t linkbuf_len = strlen(dev_net_tun) + 2;
+ char linkbuf[linkbuf_len], *fdinfo;
+ int pid, fd;
+ FILE *f;
+
+ if (sscanf(*fd_path, "/proc/%d/fd/%d", &pid, &fd) != 2)
+ goto next;
+
+ if (pid == getpid())
+ goto next;
+
+ err = readlink(*fd_path, linkbuf, linkbuf_len - 1);
+ if (err < 0) {
+ perror("readlink");
+ goto next;
+ }
+ linkbuf[err] = '\0';
+ if (strcmp(dev_net_tun, linkbuf))
+ goto next;
+
+ if (asprintf(&fdinfo, "/proc/%d/fdinfo/%d", pid, fd) < 0)
+ goto next;
+
+ f = fopen(fdinfo, "r");
+ free(fdinfo);
+ if (!f) {
+ perror("fopen");
+ goto next;
+ }
+
+ while (!feof(f)) {
+ char *key = NULL, *value = NULL;
+
+ err = fscanf(f, "%m[^:]: %ms\n", &key, &value);
+ if (err == EOF) {
+ if (ferror(f))
+ perror("fscanf");
+ break;
+ } else if (err == 2 &&
+ !strcmp("iff", key) && !strcmp(name, value)) {
+ char *pname = pid_name(pid);
+ printf(" %s(%d)", pname ? pname : "<NULL>", pid);
+ free(pname);
+ }
+
+ free(key);
+ free(value);
+ }
+ if (fclose(f))
+ perror("fclose");
+
+next:
+ ++fd_path;
+ }
+
+ globfree(&globbuf);
+ return;
+}
+
+
static int do_show(int argc, char **argv)
{
DIR *dir;
@@ -302,6 +406,11 @@ static int do_show(int argc, char **argv)
if (group != -1)
printf(" group %ld", group);
printf("\n");
+ if (show_details) {
+ printf("\tAttached to processes:");
+ show_processes(d->d_name);
+ printf("\n");
+ }
}
closedir(dir);
return 0;
--
2.7.4
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