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tun.c
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tun.c
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#include <unistd.h>
#include <sys/socket.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <sys/ioctl.h>
// MAO required on Centos 6 (linux-3.18.1 kernel)
#include <linux/filter.h>
#include "cr_options.h"
#include "imgset.h"
#include "protobuf.h"
#include "cr-show.h"
#include "string.h"
#include "files.h"
#include "files-reg.h"
#include "tun.h"
#include "net.h"
#include "namespaces.h"
#include "protobuf/tun.pb-c.h"
#ifndef IFF_PERSIST
#define IFF_PERSIST 0x0800
#endif
#ifndef IFF_NOFILTER
#define IFF_NOFILTER 0x1000
#endif
#ifndef TUNSETQUEUE
#define TUNSETQUEUE _IOW('T', 217, int)
#define IFF_ATTACH_QUEUE 0x0200
#define IFF_DETACH_QUEUE 0x0400
#endif
/*
* Absense of the 1st ioctl means we cannot restore tun link. But
* since the 2nd one appeared at the same time, we'll "check" this
* by trying to dump filter and abort dump if it's not there.
*/
#ifndef TUNSETIFINDEX
#define TUNSETIFINDEX _IOW('T', 218, unsigned int)
#endif
#ifndef TUNGETFILTER
#define TUNGETFILTER _IOR('T', 219, struct sock_fprog)
#endif
#define TUN_DEV_GEN_PATH "/dev/net/tun"
int check_tun_cr(int no_tun_err)
{
int fd, idx = 13, ret;
fd = open(TUN_DEV_GEN_PATH, O_RDWR);
if (fd < 0) {
pr_perror("Can't check tun support");
return no_tun_err;
}
ret = ioctl(fd, TUNSETIFINDEX, &idx);
if (ret < 0)
pr_perror("No proper support for tun dump/restore");
close(fd);
return ret;
}
static LIST_HEAD(tun_links);
struct tun_link {
char name[IFNAMSIZ];
struct list_head l;
union {
struct {
unsigned flags;
} rst;
struct {
unsigned sndbuf;
unsigned vnethdr;
} dmp;
};
};
static int list_tun_link(NetDeviceEntry *nde)
{
struct tun_link *tl;
tl = xmalloc(sizeof(*tl));
if (!tl)
return -1;
strlcpy(tl->name, nde->name, sizeof(tl->name));
/*
* Keep tun-flags not only for persistency fixup (see
* commend below), but also for TUNSETIFF -- we must
* open the device with the same flags it should live
* with (i.e. -- with which it was created.
*/
tl->rst.flags = nde->tun->flags;
list_add_tail(&tl->l, &tun_links);
return 0;
}
static struct tun_link *find_tun_link(char *name)
{
struct tun_link *tl;
list_for_each_entry(tl, &tun_links, l)
if (!strcmp(tl->name, name))
return tl;
return NULL;
}
static struct tun_link *__dump_tun_link_fd(int fd, char *name, unsigned flags)
{
struct tun_link *tl;
struct sock_fprog flt;
tl = xmalloc(sizeof(*tl));
if (!tl)
goto err;
strlcpy(tl->name, name, sizeof(tl->name));
if (ioctl(fd, TUNGETVNETHDRSZ, &tl->dmp.vnethdr) < 0) {
pr_perror("Can't dump vnethdr size for %s", name);
goto err;
}
if (ioctl(fd, TUNGETSNDBUF, &tl->dmp.sndbuf) < 0) {
pr_perror("Can't dump sndbuf for %s", name);
goto err;
}
if (flags & IFF_TAP) {
pr_debug("Checking filter for tap %s\n", name);
if (ioctl(fd, TUNGETFILTER, &flt) < 0) {
pr_perror("Can't get tun filter for %s", name);
goto err;
}
/*
* TUN filters are tricky -- the program itself is 'somewhere'
* in the task's memory, so we can't get one for unattached
* persistent device. The only way for doing it is opening the
* device with IFF_NOFILTER and attaching some fake one :(
*/
if (flt.len != 0) {
pr_err("Can't dump %s with filter on-board\n", name);
goto err;
}
} else if (!(flags & IFF_NOFILTER)) {
pr_err("No info about %s filter, kernel is too old\n", name);
goto err;
}
return tl;
err:
xfree(tl);
return NULL;
}
static struct tun_link *dump_tun_link_fd(int fd, char *name, unsigned flags)
{
struct tun_link *tl;
tl = find_tun_link(name);
if (tl)
return tl;
tl = __dump_tun_link_fd(fd, name, flags);
if (tl)
/*
* Keep this in list till links dumping code starts.
* We can't let it dump all this stuff itself, since
* multiple attaches to one tun device is limited and
* we may not be able to it that late.
*
* For persistent detached devices the get_tun_link_fd
* will attach to the device and get the needed stuff.
*/
list_add(&tl->l, &tun_links);
return tl;
}
static int open_tun_dev(char *name, unsigned int idx, unsigned flags)
{
int fd;
struct ifreq ifr;
fd = open(TUN_DEV_GEN_PATH, O_RDWR);
if (fd < 0) {
pr_perror("Can't open tun device");
return -1;
}
if (idx) {
pr_debug(" restoring %u for %s tun\n", idx, name);
if (ioctl(fd, TUNSETIFINDEX, &idx) < 0) {
pr_perror("Can't restore tun's index");
goto err;
}
}
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
ifr.ifr_flags = flags;
if (ioctl(fd, TUNSETIFF, &ifr)) {
pr_perror("Can't create tun device");
goto err;
}
return fd;
err:
close(fd);
return -1;
}
static struct tun_link *get_tun_link_fd(char *name, unsigned flags)
{
struct tun_link *tl;
int fd;
tl = find_tun_link(name);
if (tl)
return tl;
/*
* If we haven't found this thing, then the
* device we see via netlink exists w/o any fds
* attached, i.e. -- it's persistent
*/
if (!(flags & IFF_PERSIST)) {
pr_err("No fd infor for non persistent tun device %s\n", name);
return NULL;
}
/*
* Kernel will try to attach filter (if it exists) to our memory,
* avoid this.
*/
flags |= IFF_NOFILTER;
fd = open_tun_dev(name, 0, flags);
if (fd < 0)
return NULL;
tl = __dump_tun_link_fd(fd, name, flags);
close(fd);
return tl;
}
static int dump_tunfile(int lfd, u32 id, const struct fd_parms *p)
{
int ret;
struct cr_img *img;
TunfileEntry tfe = TUNFILE_ENTRY__INIT;
struct ifreq ifr;
if (!(root_ns_mask & CLONE_NEWNET)) {
pr_err("Net namespace is required to dump tun link\n");
return -1;
}
if (dump_one_reg_file(lfd, id, p))
return -1;
pr_info("Dumping tun-file %d with id %#x\n", lfd, id);
tfe.id = id;
ret = ioctl(lfd, TUNGETIFF, &ifr);
if (ret < 0) {
if (errno != EBADFD) {
pr_perror("Can't dump tun-file device");
return -1;
}
/*
* Otherwise this is just opened file with not yet attached
* tun device. Go agead an write the respective entry.
*/
} else {
tfe.netdev = ifr.ifr_name;
pr_info("`- attached to device %s (flags %x)\n", tfe.netdev, ifr.ifr_flags);
if (ifr.ifr_flags & IFF_DETACH_QUEUE) {
tfe.has_detached = true;
tfe.detached = true;
}
if (dump_tun_link_fd(lfd, tfe.netdev, ifr.ifr_flags) == NULL)
return -1;
}
img = img_from_set(glob_imgset, CR_FD_TUNFILE);
return pb_write_one(img, &tfe, PB_TUNFILE);
}
const struct fdtype_ops tunfile_dump_ops = {
.type = FD_TYPES__TUNF,
.dump = dump_tunfile,
};
struct tunfile_info {
struct file_desc d;
TunfileEntry *tfe;
};
static int tunfile_open(struct file_desc *d)
{
int fd;
struct tunfile_info *ti;
struct ifreq ifr;
struct tun_link *tl;
ti = container_of(d, struct tunfile_info, d);
fd = open_reg_by_id(ti->tfe->id);
if (fd < 0)
return -1;
if (!ti->tfe->netdev)
/* just-opened tun file */
return fd;
tl = find_tun_link(ti->tfe->netdev);
if (!tl) {
pr_err("No tun device for file %s\n", ti->tfe->netdev);
goto err;
}
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, tl->name, sizeof(ifr.ifr_name));
ifr.ifr_flags = tl->rst.flags;
if (ioctl(fd, TUNSETIFF, &ifr) < 0) {
pr_perror("Can't attach tunfile to device");
goto err;
}
if (ti->tfe->has_detached && ti->tfe->detached) {
pr_info("Detaching from %s queue\n", ti->tfe->netdev);
ifr.ifr_flags = IFF_DETACH_QUEUE;
if (ioctl(fd, TUNSETQUEUE, &ifr) < 0) {
pr_perror("Can't detach queue");
goto err;
}
}
if (!(tl->rst.flags & IFF_PERSIST)) {
pr_info("Dropping persistency for %s\n", tl->name);
if (ioctl(fd, TUNSETPERSIST, 0) < 0) {
pr_perror("Error dropping persistency");
goto err;
}
}
return fd;
err:
close(fd);
return -1;
}
static struct file_desc_ops tunfile_desc_ops = {
.type = FD_TYPES__TUNF,
.open = tunfile_open,
};
static int collect_one_tunfile(void *o, ProtobufCMessage *base)
{
struct tunfile_info *ti = o;
ti->tfe = pb_msg(base, TunfileEntry);
file_desc_add(&ti->d, ti->tfe->id, &tunfile_desc_ops);
pr_info("Collected %s tunfile\n", ti->tfe->netdev);
return 0;
}
struct collect_image_info tunfile_cinfo = {
.fd_type = CR_FD_TUNFILE,
.pb_type = PB_TUNFILE,
.priv_size = sizeof(struct tunfile_info),
.collect = collect_one_tunfile,
};
int dump_tun_link(NetDeviceEntry *nde, struct cr_imgset *fds)
{
TunLinkEntry tle = TUN_LINK_ENTRY__INIT;
char spath[64];
char buf[64];
int ret = 0;
struct tun_link *tl;
sprintf(spath, "class/net/%s/tun_flags", nde->name);
ret |= read_ns_sys_file(spath, buf, sizeof(buf));
tle.flags = strtol(buf, NULL, 0);
sprintf(spath, "class/net/%s/owner", nde->name);
ret |= read_ns_sys_file(spath, buf, sizeof(buf));
tle.owner = strtol(buf, NULL, 10);
sprintf(spath, "class/net/%s/group", nde->name);
ret |= read_ns_sys_file(spath, buf, sizeof(buf));
tle.group = strtol(buf, NULL, 10);
if (ret < 0)
return ret;
tl = get_tun_link_fd(nde->name, tle.flags);
if (!tl)
return ret;
tle.vnethdr = tl->dmp.vnethdr;
tle.sndbuf = tl->dmp.sndbuf;
nde->tun = &tle;
return write_netdev_img(nde, fds);
}
int restore_one_tun(NetDeviceEntry *nde, int nlsk)
{
int fd, ret = -1, aux;
if (!nde->tun) {
pr_err("Corrupted TUN link entry %x\n", nde->ifindex);
return -1;
}
pr_info("Restoring tun device %s\n", nde->name);
fd = open_tun_dev(nde->name, nde->ifindex, nde->tun->flags);
if (fd < 0)
return -1;
aux = nde->tun->owner;
if ((aux != -1) && ioctl(fd, TUNSETOWNER, aux) < 0) {
pr_perror("Can't set owner");
goto out;
}
aux = nde->tun->group;
if ((aux != -1) && ioctl(fd, TUNSETGROUP, aux) < 0) {
pr_perror("Can't set group");
goto out;
}
aux = nde->tun->sndbuf;
if (ioctl(fd, TUNSETSNDBUF, &aux) < 0) {
pr_perror("Can't set sndbuf");
goto out;
}
aux = nde->tun->vnethdr;
if (ioctl(fd, TUNSETVNETHDRSZ, &aux) < 0) {
pr_perror("Can't set vnethdr");
goto out;
}
/*
* Set this device persistent anyway and schedule
* the persistence drop if it should not be such.
* The first _real_ opener will do it.
*/
if (ioctl(fd, TUNSETPERSIST, 1)) {
pr_perror("Can't make tun device persistent");
goto out;
}
if (restore_link_parms(nde, nlsk)) {
pr_err("Error restoring %s link params\n", nde->name);
goto out;
}
ret = list_tun_link(nde);
out:
close(fd);
return ret;
}