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unix: restore sockets on correct mount points

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Currently we restore all sockets in the root mount namespace, because we
were not able to get any information about a mount point where a socket
is bound. It is obviously incorrect in some cases.

In 4.10 kernel, we added the SIOCUNIXFILE ioctl for unix sockets.  This
ioctl opens a file to which a socket is bound and returns a file
descriptor.

This new ioctl allows us to get mnt_id by reading fdinfo, and mnt_id
is enough to find a proper mount point and a mount namespace.

The logic of this patch is straight forward. On dump, we save mnt_id for
sockets, on restore we find a mount namespace by mnt_id and restore this
socket in its mount namespace.

Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
This commit is contained in:
Andrey Vagin 2018-03-16 20:24:26 +03:00 • committed by Andrei Vagin
parent f7a0a7c3b7
commit dcf688b0d6
2 changed files with 92 additions and 23 deletions
Download patch file Download diff file Expand all files Collapse all files

114
criu/sk-unix.c
View file

@ -223,6 +223,27 @@ int kerndat_socket_unix_file(void)
return 0;
}
static int get_mnt_id(int lfd, int *mnt_id)
{
struct fdinfo_common fdinfo = { .mnt_id = -1 };
int ret, fd;
fd = ioctl(lfd, SIOCUNIXFILE);
if (fd < 0) {
pr_perror("Unable to get a socker file descriptor");
return -1;
}
ret = parse_fdinfo(fd, FD_TYPES__UND, &fdinfo);
close(fd);
if (ret < 0)
return -1;
*mnt_id = fdinfo.mnt_id;
return 0;
}
static int resolve_rel_name(u32 id, struct unix_sk_desc *sk, const struct fd_parms *p, char **pdir)
{
const char *dirs[] = { "cwd", "root" };
@ -293,7 +314,7 @@ err:
return -ENOENT;
}
static int unix_resolve_name(u32 id, struct unix_sk_desc *d,
static int unix_resolve_name(int lfd, u32 id, struct unix_sk_desc *d,
UnixSkEntry *ue, const struct fd_parms *p);
static int dump_one_unix_fd(int lfd, u32 id, const struct fd_parms *p)
{
@ -347,7 +368,7 @@ static int dump_one_unix_fd(int lfd, u32 id, const struct fd_parms *p)
ue->opts = skopts;
ue->uflags = 0;
if (unix_resolve_name(id, sk, ue, p))
if (unix_resolve_name(lfd, id, sk, ue, p))
goto err;
/*
@ -523,7 +544,7 @@ const struct fdtype_ops unix_dump_ops = {
.dump = dump_one_unix_fd,
};
static int unix_resolve_name(u32 id, struct unix_sk_desc *d,
static int unix_resolve_name(int lfd, u32 id, struct unix_sk_desc *d,
UnixSkEntry *ue, const struct fd_parms *p)
{
char *name = d->name;
@ -532,12 +553,22 @@ static int unix_resolve_name(u32 id, struct unix_sk_desc *d,
struct ns_id *ns;
struct stat st;
int mntns_root;
int ret;
int ret, mnt_id;
if (d->namelen == 0 || name[0] == '\0')
return 0;
ns = lookup_ns_by_id(root_item->ids->mnt_ns_id, &mnt_ns_desc);
if (kdat.sk_unix_file && (root_ns_mask & CLONE_NEWNS)) {
if (get_mnt_id(lfd, &mnt_id))
return -1;
ue->mnt_id = mnt_id;
ue->has_mnt_id = mnt_id;
}
if (ue->mnt_id >= 0)
ns = lookup_nsid_by_mnt_id(ue->mnt_id);
else
ns = lookup_ns_by_id(root_item->ids->mnt_ns_id, &mnt_ns_desc);
if (!ns) {
ret = -ENOENT;
goto out;
@ -1083,12 +1114,17 @@ static int restore_sk_common(int fd, struct unix_sk_info *ui)
return 0;
}
static void revert_unix_sk_cwd(int *prev_cwd_fd, int *root_fd)
static int revert_unix_sk_cwd(int *prev_cwd_fd, int *root_fd, int *ns_fd)
{
int ret = 0;
if (*ns_fd >= 0 && restore_ns(*ns_fd, &mnt_ns_desc))
ret = -1;
if (*root_fd >= 0) {
if (fchdir(*root_fd) || chroot("."))
pr_perror("Can't revert root directory");
close_safe(root_fd);
ret = -1;
}
if (prev_cwd_fd && *prev_cwd_fd >= 0) {
if (fchdir(*prev_cwd_fd))
@ -1097,14 +1133,38 @@ static void revert_unix_sk_cwd(int *prev_cwd_fd, int *root_fd)
pr_debug("Reverted working dir\n");
close(*prev_cwd_fd);
*prev_cwd_fd = -1;
ret = -1;
}
return ret;
}
static int prep_unix_sk_cwd(struct unix_sk_info *ui, int *prev_cwd_fd, int *prev_root_fd)
static int prep_unix_sk_cwd(struct unix_sk_info *ui, int *prev_cwd_fd,
int *prev_root_fd, int *prev_mntns_fd)
{
static struct ns_id *root = NULL;
static struct ns_id *root = NULL, *ns;
int fd;
if (prev_mntns_fd && ui->name[0] && ui->ue->mnt_id >= 0) {
struct ns_id *mntns = lookup_nsid_by_mnt_id(ui->ue->mnt_id);
int ns_fd;
if (mntns == NULL) {
pr_err("Unable to find the %d mount\n", ui->ue->mnt_id);
return -1;
}
ns_fd = fdstore_get(mntns->mnt.nsfd_id);
if (ns_fd < 0)
return -1;
if (switch_ns_by_fd(ns_fd, &mnt_ns_desc, prev_mntns_fd))
return -1;
set_proc_self_fd(-1);
close(ns_fd);
}
*prev_cwd_fd = open(".", O_RDONLY);
if (*prev_cwd_fd < 0) {
pr_perror("Can't open current dir");
@ -1112,15 +1172,23 @@ static int prep_unix_sk_cwd(struct unix_sk_info *ui, int *prev_cwd_fd, int *prev
}
if (prev_root_fd && (root_ns_mask & CLONE_NEWNS)) {
if (root == NULL)
root = lookup_ns_by_id(root_item->ids->mnt_ns_id, &mnt_ns_desc);
if (ui->ue->mnt_id >= 0) {
ns = lookup_nsid_by_mnt_id(ui->ue->mnt_id);
if (ns == NULL)
goto err;
} else {
if (root == NULL)
root = lookup_ns_by_id(root_item->ids->mnt_ns_id,
&mnt_ns_desc);
ns = root;
}
*prev_root_fd = open("/", O_RDONLY);
if (*prev_root_fd < 0) {
pr_perror("Can't open current root");
goto err;
}
fd = fdstore_get(root->mnt.root_fd_id);
fd = fdstore_get(ns->mnt.root_fd_id);
if (fd < 0) {
pr_err("Can't get root fd\n");
goto err;
@ -1159,7 +1227,7 @@ static int post_open_standalone(struct file_desc *d, int fd)
struct unix_sk_info *ui;
struct unix_sk_info *peer;
struct sockaddr_un addr;
int cwd_fd = -1, root_fd = -1;
int cwd_fd = -1, root_fd = -1, ns_fd = -1;
ui = container_of(d, struct unix_sk_info, d);
BUG_ON((ui->flags & (USK_PAIR_MASTER | USK_PAIR_SLAVE)) ||
@ -1188,19 +1256,19 @@ static int post_open_standalone(struct file_desc *d, int fd)
pr_info("\tConnect %#x to %#x\n", ui->ue->ino, peer->ue->ino);
if (prep_unix_sk_cwd(peer, &cwd_fd, NULL))
if (prep_unix_sk_cwd(peer, &cwd_fd, NULL, &ns_fd))
return -1;
if (connect(fd, (struct sockaddr *)&addr,
sizeof(addr.sun_family) +
peer->ue->name.len) < 0) {
pr_perror("Can't connect %#x socket", ui->ue->ino);
revert_unix_sk_cwd(&cwd_fd, &root_fd);
revert_unix_sk_cwd(&cwd_fd, &root_fd, &ns_fd);
return -1;
}
ui->is_connected = true;
revert_unix_sk_cwd(&cwd_fd, &root_fd);
revert_unix_sk_cwd(&cwd_fd, &root_fd, &ns_fd);
restore_queue:
if (peer->queuer == ui &&
@ -1216,7 +1284,7 @@ restore_sk_common:
static int bind_unix_sk(int sk, struct unix_sk_info *ui)
{
struct sockaddr_un addr;
int cwd_fd = -1, root_fd = -1;
int cwd_fd = -1, root_fd = -1, ns_fd = -1;
int ret = -1;
if (ui->ue->name.len == 0)
@ -1238,10 +1306,10 @@ static int bind_unix_sk(int sk, struct unix_sk_info *ui)
addr.sun_family = AF_UNIX;
memcpy(&addr.sun_path, ui->name, ui->ue->name.len);
if (prep_unix_sk_cwd(ui, &cwd_fd, NULL))
return -1;
if (ui->ue->name.len) {
if (ui->name[0] && prep_unix_sk_cwd(ui, &cwd_fd, NULL, &ns_fd))
return -1;
ret = bind(sk, (struct sockaddr *)&addr,
sizeof(addr.sun_family) + ui->ue->name.len);
if (ret < 0) {
@ -1324,7 +1392,7 @@ static int bind_unix_sk(int sk, struct unix_sk_info *ui)
ret = 0;
done:
revert_unix_sk_cwd(&cwd_fd, &root_fd);
revert_unix_sk_cwd(&cwd_fd, &root_fd, &ns_fd);
return ret;
}
@ -1665,12 +1733,12 @@ static struct file_desc_ops unix_desc_ops = {
*/
static void unlink_stale(struct unix_sk_info *ui)
{
int ret, cwd_fd = -1, root_fd = -1;
int ret, cwd_fd = -1, root_fd = -1, ns_fd = -1;
if (ui->name[0] == '\0' || (ui->ue->uflags & USK_EXTERN))
return;
if (prep_unix_sk_cwd(ui, &cwd_fd, &root_fd))
if (prep_unix_sk_cwd(ui, &cwd_fd, &root_fd, NULL))
return;
ret = unlinkat(AT_FDCWD, ui->name, 0) ? -1 : 0;
@ -1680,7 +1748,7 @@ static void unlink_stale(struct unix_sk_info *ui)
ui->name ? (ui->name[0] ? ui->name : &ui->name[1]) : "-",
ui->name_dir ? ui->name_dir : "-");
}
revert_unix_sk_cwd(&cwd_fd, &root_fd);
revert_unix_sk_cwd(&cwd_fd, &root_fd, &ns_fd);
}
static void try_resolve_unix_peer(struct unix_sk_info *ui);

1
images/sk-unix.proto
View file

@ -50,4 +50,5 @@ message unix_sk_entry {
optional bool deleted = 15;
optional uint32 ns_id = 16;
optional sint32 mnt_id = 17 [default = -1];
}