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network/tuntap: manage tun/tap fds by manager

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Otherwise, when a .netdev file for tun or tap netdev is updated,
reloading the file leaks the previous file descriptor.
This commit is contained in:
Yu Watanabe 2024-11-09 02:48:17 +09:00
parent 69bd661a2d
commit 34e5440fb2
2 changed files with 78 additions and 70 deletions
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147
src/network/netdev/tuntap.c
View File

@ -36,15 +36,33 @@ static TunTap* TUNTAP(NetDev *netdev) {
DEFINE_PRIVATE_HASH_OPS_FULL(named_fd_hash_ops, char, string_hash_func, string_compare_func, free, void, close_fd_ptr);
int manager_add_tuntap_fd(Manager *m, int fd, const char *name) {
static int manager_add_tuntap_fd_impl(Manager *m, int fd, const char *name) {
_cleanup_free_ char *tuntap_name = NULL;
const char *p;
int r;
assert(m);
assert(fd >= 0);
assert(name);
tuntap_name = strdup(name);
if (!tuntap_name)
return log_oom_debug();
r = hashmap_ensure_put(&m->tuntap_fds_by_name, &named_fd_hash_ops, tuntap_name, FD_TO_PTR(fd));
if (r < 0)
return log_debug_errno(r, "Failed to store tuntap fd: %m");
TAKE_PTR(tuntap_name);
return 0;
}
int manager_add_tuntap_fd(Manager *m, int fd, const char *name) {
const char *p;
assert(m);
assert(fd >= 0);
assert(name);
p = startswith(name, "tuntap-");
if (!p)
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Received unknown fd (%s).", name);
@ -52,66 +70,76 @@ int manager_add_tuntap_fd(Manager *m, int fd, const char *name) {
if (!ifname_valid(p))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Received tuntap fd with invalid name (%s).", p);
tuntap_name = strdup(p);
if (!tuntap_name)
return log_oom_debug();
return manager_add_tuntap_fd_impl(m, fd, p);
}
r = hashmap_ensure_put(&m->tuntap_fds_by_name, &named_fd_hash_ops, tuntap_name, FD_TO_PTR(fd));
static int netdev_take_tuntap_fd(Manager *m, const char *ifname) {
_unused_ _cleanup_free_ char *name = NULL;
void *p;
assert(m);
assert(ifname);
p = hashmap_remove2(m->tuntap_fds_by_name, ifname, (void**) &name);
if (!p)
return -EBADF;
return PTR_TO_FD(p);
}
static int netdev_push_tuntap_fd(NetDev *netdev, int fd) {
_unused_ _cleanup_close_ int fd_old = -EBADF;
int r;
assert(netdev->manager);
fd_old = netdev_take_tuntap_fd(netdev->manager, netdev->ifname);
if (!TUNTAP(netdev)->keep_fd)
return 0;
r = manager_add_tuntap_fd_impl(netdev->manager, fd, netdev->ifname);
if (r < 0)
return log_debug_errno(r, "Failed to store tuntap fd: %m");
return r;
TAKE_PTR(tuntap_name);
return 0;
(void) notify_push_fdf(fd, "tuntap-%s", netdev->ifname);
return 1; /* saved */
}
static void manager_close_and_notify_tuntap_fd(Manager *m, const char *ifname) {
assert(m);
assert(ifname);
/* netdev_take_tuntap_fd() may invalidate ifname. Hence, need to create fdname earlier. */
const char *fdname = strjoina("tuntap-", ifname);
close_and_notify_warn(netdev_take_tuntap_fd(m, ifname), fdname);
}
void manager_clear_unmanaged_tuntap_fds(Manager *m) {
char *name;
const char *name;
void *p;
assert(m);
while ((p = hashmap_steal_first_key_and_value(m->tuntap_fds_by_name, (void**) &name))) {
close_and_notify_warn(PTR_TO_FD(p), name);
name = mfree(name);
HASHMAP_FOREACH_KEY(p, name, m->tuntap_fds_by_name) {
NetDev *netdev;
if (netdev_get(m, name, &netdev) < 0 ||
!IN_SET(netdev->kind, NETDEV_KIND_TAP, NETDEV_KIND_TUN) ||
!TUNTAP(netdev)->keep_fd)
manager_close_and_notify_tuntap_fd(m, name);
}
}
static int tuntap_take_fd(NetDev *netdev) {
_cleanup_free_ char *name = NULL;
void *p;
int r;
assert(netdev);
assert(netdev->manager);
r = link_get_by_name(netdev->manager, netdev->ifname, NULL);
if (r < 0)
return r;
p = hashmap_remove2(netdev->manager->tuntap_fds_by_name, netdev->ifname, (void**) &name);
if (!p)
return -ENOENT;
log_netdev_debug(netdev, "Found file descriptor in fd store.");
return PTR_TO_FD(p);
}
static int netdev_create_tuntap(NetDev *netdev) {
_cleanup_close_ int fd = -EBADF;
struct ifreq ifr = {};
TunTap *t;
TunTap *t = TUNTAP(netdev);
int r;
assert(netdev);
assert(netdev->manager);
t = TUNTAP(netdev);
assert(t);
fd = TAKE_FD(t->fd);
if (fd < 0)
fd = tuntap_take_fd(netdev);
if (fd < 0)
fd = open(TUN_DEV, O_RDWR|O_CLOEXEC);
fd = open(TUN_DEV, O_RDWR|O_CLOEXEC);
if (fd < 0)
return log_netdev_error_errno(netdev, errno, "Failed to open " TUN_DEV ": %m");
@ -175,42 +203,25 @@ static int netdev_create_tuntap(NetDev *netdev) {
if (ioctl(fd, TUNSETPERSIST, 1) < 0)
return log_netdev_error_errno(netdev, errno, "TUNSETPERSIST failed: %m");
if (t->keep_fd) {
t->fd = TAKE_FD(fd);
(void) notify_push_fdf(t->fd, "tuntap-%s", netdev->ifname);
}
r = netdev_push_tuntap_fd(netdev, fd);
if (r < 0)
return log_netdev_warning_errno(netdev, r, "Failed to save TUN/TAP fd: %m");
if (r > 0)
TAKE_FD(fd);
netdev_enter_ready(netdev);
return 0;
}
static void tuntap_init(NetDev *netdev) {
TunTap *t;
assert(netdev);
t = TUNTAP(netdev);
assert(t);
t->fd = -EBADF;
}
static void tuntap_drop(NetDev *netdev) {
TunTap *t;
assert(netdev);
t = TUNTAP(netdev);
assert(t);
t->fd = close_and_notify_warn(t->fd, netdev->ifname);
manager_close_and_notify_tuntap_fd(netdev->manager, netdev->ifname);
}
static void tuntap_done(NetDev *netdev) {
TunTap *t;
TunTap *t = TUNTAP(netdev);
assert(netdev);
t = TUNTAP(netdev);
assert(t);
t->fd = safe_close(t->fd);
t->user_name = mfree(t->user_name);
t->group_name = mfree(t->group_name);
}
@ -237,7 +248,6 @@ const NetDevVTable tun_vtable = {
.object_size = sizeof(TunTap),
.sections = NETDEV_COMMON_SECTIONS "Tun\0",
.config_verify = tuntap_verify,
.init = tuntap_init,
.drop = tuntap_drop,
.done = tuntap_done,
.create = netdev_create_tuntap,
@ -249,7 +259,6 @@ const NetDevVTable tap_vtable = {
.object_size = sizeof(TunTap),
.sections = NETDEV_COMMON_SECTIONS "Tap\0",
.config_verify = tuntap_verify,
.init = tuntap_init,
.drop = tuntap_drop,
.done = tuntap_done,
.create = netdev_create_tuntap,

1
src/network/netdev/tuntap.h
View File

@ -8,7 +8,6 @@ typedef struct TunTap TunTap;
struct TunTap {
NetDev meta;
int fd;
char *user_name;
char *group_name;
bool multi_queue;