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tap: Bring up tap device too, configure previous MAC address if any

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In case we need to reinitialise the tap interface, make that
relatively transparent to processes running in the namespace.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2021-09-27 00:26:15 +02:00
parent a491c8ee3c
commit 8cc50c346b
1 changed files with 74 additions and 2 deletions
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76
tap.c
View file

@ -20,6 +20,7 @@
#include <string.h> #include <string.h>
#include <net/ethernet.h> #include <net/ethernet.h>
#include <net/if.h> #include <net/if.h>
#include <net/if_arp.h>
#include <netinet/in.h> #include <netinet/in.h>
#include <arpa/inet.h> #include <arpa/inet.h>
#include <stdint.h> #include <stdint.h>
@ -868,6 +869,72 @@ fail:
return 0; return 0;
} }
/**
* struct tap_sock_if_up_ns_arg - Arguments for tap_sock_if_up_ns()
* @c: Execution context
* @target_pid: Target namespace PID
* @ifname: Interface name of tap device
*/
struct tap_sock_if_up_ns_arg {
struct ctx *c;
int target_pid;
char ifname[IFNAMSIZ];
};
/**
* tap_sock_if_up_ns() - Bring up tap, get or set MAC address (if we have one)
* @ifname: Interface name
*
* Return: 0 -- not fundamental, the interface can be brought up later
*/
static int tap_sock_if_up_ns(void *arg)
{
struct ifreq ifr = { .ifr_flags = IFF_UP };
struct tap_sock_if_up_ns_arg *a;
int fd;
a = (struct tap_sock_if_up_ns_arg *)arg;
if (ns_enter(a->target_pid))
return 0;
if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
perror("socket for ioctl");
return 0;
}
strncpy(ifr.ifr_name, a->ifname, IFNAMSIZ);
if (ioctl(fd, SIOCSIFFLAGS, &ifr)) {
perror("SIOCSIFFLAGS ioctl for tap");
goto out;
}
if (memcmp(a->c->mac_guest,
((uint8_t [ETH_ALEN]){ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }),
ETH_ALEN)) {
ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;
memcpy(ifr.ifr_hwaddr.sa_data, a->c->mac_guest, ETH_ALEN);
if (ioctl(fd, SIOCSIFHWADDR, &ifr) < 0) {
perror("SIOCSIFHWADDR ioctl for tap");
goto out;
}
} else {
if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
perror("SIOCGIFHWADDR ioctl for tap");
goto out;
}
memcpy(a->c->mac_guest, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
proto_update_l2_buf(a->c->mac_guest, NULL, NULL);
}
out:
close(fd);
return 0;
}
/** /**
* tap_sock_init_tun() - Set up tuntap file descriptor * tap_sock_init_tun() - Set up tuntap file descriptor
* @c: Execution context * @c: Execution context
@ -875,8 +942,7 @@ fail:
static void tap_sock_init_tun(struct ctx *c) static void tap_sock_init_tun(struct ctx *c)
{ {
struct ifreq ifr = { .ifr_flags = IFF_TAP | IFF_NO_PI }; struct ifreq ifr = { .ifr_flags = IFF_TAP | IFF_NO_PI };
struct tap_sock_if_up_ns_arg ifup_arg;
strncpy(ifr.ifr_name, c->pasta_ifn, IFNAMSIZ);
NS_CALL(tap_sock_init_tun_ns, &c->pasta_pid); NS_CALL(tap_sock_init_tun_ns, &c->pasta_pid);
if (tun_ns_fd == -1) { if (tun_ns_fd == -1) {
@ -884,11 +950,17 @@ static void tap_sock_init_tun(struct ctx *c)
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
strncpy(ifr.ifr_name, c->pasta_ifn, IFNAMSIZ);
if (ioctl(tun_ns_fd, TUNSETIFF, &ifr)) { if (ioctl(tun_ns_fd, TUNSETIFF, &ifr)) {
perror("TUNSETIFF ioctl"); perror("TUNSETIFF ioctl");
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
strncpy(ifup_arg.ifname, c->pasta_ifn, IFNAMSIZ);
ifup_arg.target_pid = c->pasta_pid;
ifup_arg.c = c;
NS_CALL(tap_sock_if_up_ns, (void *)&ifup_arg);
pcap_init(c, c->pasta_pid); pcap_init(c, c->pasta_pid);
c->fd_tap = tun_ns_fd; c->fd_tap = tun_ns_fd;