The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear
at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.32
------>
commit fc474d04208e32b045a68f1e44a287fb0a437ef6
Author: Cyrill Gorcunov <[email protected]>
Date: Mon May 24 18:31:55 2021 +0300
ve/tty: Provide interface for current tty inheritance
When fork() is called the current controlling terminal is inherited
by a child process. But in criu we fork all process first and then
restore their files, thus if terminal is opened in some children
its reference get lost. We refuse to checkpoint such configurations
at the moment in criu itself.
So to be able to restore this kind of container we need a way to
propagate controlling terminal to children processes, and here
is an interface "ve.ctty" entry on toplevel ve cgroup. One have
to pass pid of the donor task in first position followed by a series
of recipient pids.
https://jira.sw.ru/browse/PSBM-76490
CC: Andrey Vagin <[email protected]>
CC: Andrey Ryabinin <[email protected]>
CC: Konstantin Khorenko <[email protected]>
CC: "Denis V. Lunev" <[email protected]>
Signed-off-by: Cyrill Gorcunov <[email protected]>
khorenko@: we'll try to push the interface for ctty set up to mainstream.
May be it will be another interface like ioctl/netlink/etc, whatever.
This work (interface to mainstream) will be done in the scope of
https://jira.sw.ru/browse/PSBM-81687
(cherry picked from vz7 commit 098099f6daaf ("ve/tty: Provide interface for
current tty inheritance"))
See also
451af50 ("cgroup: replace cftype->write_string() with cftype->write()")
VZ 8 rebase part https://jira.sw.ru/browse/PSBM-127797
Signed-off-by: Alexander Mikhalitsyn <[email protected]>
---
kernel/ve/ve.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 102 insertions(+)
diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
index 6858698d69bc..ef8fb52936bc 100644
--- a/kernel/ve/ve.c
+++ b/kernel/ve/ve.c
@@ -25,6 +25,10 @@
#include <linux/kthread.h>
#include <linux/nsproxy.h>
#include <linux/fs_struct.h>
+#include <linux/task_work.h>
+#include <linux/ctype.h>
+#include <linux/tty.h>
+
#include <uapi/linux/vzcalluser.h>
#include <net/rtnetlink.h>
@@ -1556,6 +1560,99 @@ static int ve_aio_max_nr_write(struct
cgroup_subsys_state *css,
}
#endif
+static ssize_t ve_write_ctty(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct task_struct *tsk_from, *tsk_to;
+ struct tty_struct *tty_from, *tty_to;
+ pid_t pid_from, pid_to;
+ unsigned long flags;
+ char *pids;
+ int ret;
+
+ /*
+ * Buffer format is the following
+ *
+ * pid_from pid_to pid_to ...
+ *
+ * where pid_to are pids to propagate
+ * current terminal into.
+ */
+
+ pids = skip_spaces(buf);
+ if (sscanf(pids, "%d", &pid_from) != 1)
+ return -EINVAL;
+ pids = strchr(pids, ' ');
+ if (!pids)
+ return -EINVAL;
+ pids = skip_spaces(pids);
+
+ rcu_read_lock();
+ tsk_from = find_task_by_vpid(pid_from);
+ if (tsk_from)
+ get_task_struct(tsk_from);
+ rcu_read_unlock();
+
+ if (!tsk_from)
+ return -ESRCH;
+
+ spin_lock_irqsave(&tsk_from->sighand->siglock, flags);
+ tty_from = tty_kref_get(tsk_from->signal->tty);
+ spin_unlock_irqrestore(&tsk_from->sighand->siglock, flags);
+
+ if (!tty_from) {
+ ret = -ENOTTY;
+ goto out;
+ }
+
+ ret = 0;
+ while (pids && *pids) {
+ if (sscanf(pids, "%d", &pid_to) != 1) {
+ ret = -EINVAL;
+ goto out;
+ }
+ pids = strchr(pids, ' ');
+ if (pids)
+ pids = skip_spaces(pids);
+
+ rcu_read_lock();
+ tsk_to = find_task_by_vpid(pid_to);
+ if (tsk_to)
+ get_task_struct(tsk_to);
+ rcu_read_unlock();
+
+ if (!tsk_to) {
+ ret = -ESRCH;
+ goto out;
+ }
+
+ if (tsk_from->task_ve == tsk_to->task_ve) {
+ spin_lock_irqsave(&tsk_to->sighand->siglock, flags);
+ tty_to = tsk_to->signal->tty;
+ if (!tty_to)
+ tsk_to->signal->tty = tty_kref_get(tty_from);
+ else
+ ret = -EBUSY;
+ spin_unlock_irqrestore(&tsk_to->sighand->siglock,
flags);
+ } else
+ ret = -EINVAL;
+
+ put_task_struct(tsk_to);
+
+ if (ret)
+ goto out;
+ }
+
+out:
+ tty_kref_put(tty_from);
+ put_task_struct(tsk_from);
+
+ if (!ret)
+ ret = nbytes;
+
+ return ret;
+}
+
static struct cftype ve_cftypes[] = {
{
@@ -1628,6 +1725,11 @@ static struct cftype ve_cftypes[] = {
.write_u64 = ve_aio_max_nr_write,
},
#endif
+ {
+ .name = "ctty",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .write = ve_write_ctty,
+ },
{ }
};
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