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cr-restore: block SIGCHLD for restoring namespaces

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Restore of namespaces requires executions of external tools
(ip, tar, etc). We want to know return codes, so we should
block a default sigchld handler. Before we did that for each
command, I suggest to block SIGCHLD, then restore namespace and
unblock SIGCHLD.

The default sigchld handler is used for catching target processes,
but all this processes (except a current one ) are started after
restoring namespaces.

Currently we forgot to block SIGCHLD before executing "ip",
and this bug was caught.

Reported-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Andrey Vagin
2012-09-25 15:59:13 +04:00
committed by Pavel Emelyanov
parent c4148d7907
commit e1b02a48c1
2 changed files with 25 additions and 30 deletions
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27
namespaces.c
View File

@@ -151,9 +151,19 @@ int dump_namespaces(struct pid *ns_pid, unsigned int ns_flags)
int prepare_namespace(int pid, unsigned long clone_flags)
{
sigset_t blockmask, oldmask;
int ret = -1;
pr_info("Restoring namespaces %d flags 0x%lx\n",
pid, clone_flags);
sigemptyset(&blockmask);
sigaddset(&blockmask, SIGCHLD);
if (sigprocmask(SIG_BLOCK, &blockmask, &oldmask) == -1) {
pr_perror("Can not set mask of blocked signals");
return -1;
}
/*
* On netns restore we launch an IP tool, thus we
* have to restore it _before_ altering the mount
@@ -161,15 +171,22 @@ int prepare_namespace(int pid, unsigned long clone_flags)
*/
if ((clone_flags & CLONE_NEWNET) && prepare_net_ns(pid))
return -1;
goto out;
if ((clone_flags & CLONE_NEWUTS) && prepare_utsns(pid))
return -1;
goto out;
if ((clone_flags & CLONE_NEWIPC) && prepare_ipc_ns(pid))
return -1;
goto out;
if ((clone_flags & CLONE_NEWNS) && prepare_mnt_ns(pid))
return -1;
goto out;
return 0;
ret = 0;
out:
if (sigprocmask(SIG_SETMASK, &oldmask, NULL) == -1) {
pr_perror("Can not set mask of blocked signals");
BUG();
}
return ret;
}
int try_show_namespaces(int ns_pid, struct cr_options *o)