Dmitry Konishchev
0e1ab2261c
When KeepCarrier is set, networkd doesn't close tun/tap file descriptor
preserving the active interface state, but doesn't disable its queue
which makes kernel to think that it's still active and send packets to
it.
This patch disables the created queue right after tun/tap interface
creation.
Here is the steps to reproduce the bug:
Having:
systemd/network/10-tun-test.netdev:
[NetDev]
Name=tun-test
Kind=tun
[Tun]
MultiQueue=yes
KeepCarrier=yes
systemd/network/10-tun-test.network:
[Match]
Name=tun-test
[Network]
DHCP=no
IPv6AcceptRA=false
LLMNR=false
MulticastDNS=false
Address=172.31.0.1/24
app.c:
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <linux/if.h>
#include <sys/ioctl.h>
#include <linux/if_tun.h>
int main() {
int fd;
struct ifreq ifr;
memset(&ifr, 0, sizeof ifr);
strcpy(ifr.ifr_name, "tun-test");
ifr.ifr_flags = IFF_TUN | IFF_NO_PI | IFF_MULTI_QUEUE;
if((fd = open("/dev/net/tun", O_RDWR)) < 0) {
perror("Open error");
return 1;
}
if(ioctl(fd, TUNSETIFF, &ifr)) {
perror("Configure error");
return 1;
}
puts("Ready.");
char buf[1500];
while(1) {
int size = read(fd, buf, sizeof buf);
if(size < 0) {
perror("Read error");
return 1;
}
printf("Read %d bytes.\n", size);
}
return 0;
}
Run:
* gcc -o app app.c && ./app
* ping -I tun-test 172.31.0.2
Before the patch the app shows no pings, but after it works properly.
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