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nsproxy: support CLONE_NEWTIME with setns() 

So far setns() was missing time namespace support. This was partially due
to it simply not being implemented but also because vdso_join_timens()
could still fail which made switching to multiple namespaces atomically
problematic. This is now fixed so support CLONE_NEWTIME with setns()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Andrei Vagin <avagin@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20200706154912.3248030-4-christian.brauner@ubuntu.com
This commit is contained in:
Christian Brauner 2020-07-06 17:49:11 +02:00
parent 5cfea9a106
commit 76c12881a3
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
3 changed files with 26 additions and 6 deletions
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6
include/linux/time_namespace.h
View File

@ -33,6 +33,7 @@ extern struct time_namespace init_time_ns;
#ifdef CONFIG_TIME_NS
extern int vdso_join_timens(struct task_struct *task,
struct time_namespace *ns);
extern void timens_commit(struct task_struct *tsk, struct time_namespace *ns);
static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
{
@ -96,6 +97,11 @@ static inline int vdso_join_timens(struct task_struct *task,
return 0;
}
static inline void timens_commit(struct task_struct *tsk,
struct time_namespace *ns)
{
}
static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
{
return NULL;

21
kernel/nsproxy.c
View File

@ -262,8 +262,8 @@ void exit_task_namespaces(struct task_struct *p)
static int check_setns_flags(unsigned long flags)
{
if (!flags || (flags & ~(CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
CLONE_NEWNET | CLONE_NEWUSER | CLONE_NEWPID |
CLONE_NEWCGROUP)))
CLONE_NEWNET | CLONE_NEWTIME | CLONE_NEWUSER |
CLONE_NEWPID | CLONE_NEWCGROUP)))
return -EINVAL;
#ifndef CONFIG_USER_NS
@ -290,6 +290,10 @@ static int check_setns_flags(unsigned long flags)
if (flags & CLONE_NEWNET)
return -EINVAL;
#endif
#ifndef CONFIG_TIME_NS
if (flags & CLONE_NEWTIME)
return -EINVAL;
#endif
return 0;
}
@ -464,6 +468,14 @@ static int validate_nsset(struct nsset *nsset, struct pid *pid)
}
#endif
#ifdef CONFIG_TIME_NS
if (flags & CLONE_NEWTIME) {
ret = validate_ns(nsset, &nsp->time_ns->ns);
if (ret)
goto out;
}
#endif
out:
if (pid_ns)
put_pid_ns(pid_ns);
@ -507,6 +519,11 @@ static void commit_nsset(struct nsset *nsset)
exit_sem(me);
#endif
#ifdef CONFIG_TIME_NS
if (flags & CLONE_NEWTIME)
timens_commit(me, nsset->nsproxy->time_ns);
#endif
/* transfer ownership */
switch_task_namespaces(me, nsset->nsproxy);
nsset->nsproxy = NULL;

5
kernel/time/namespace.c
View File

@ -280,7 +280,7 @@ static void timens_put(struct ns_common *ns)
put_time_ns(to_time_ns(ns));
}
static void timens_commit(struct task_struct *tsk, struct time_namespace *ns)
void timens_commit(struct task_struct *tsk, struct time_namespace *ns)
{
timens_set_vvar_page(tsk, ns);
vdso_join_timens(tsk, ns);
@ -298,9 +298,6 @@ static int timens_install(struct nsset *nsset, struct ns_common *new)
!ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
return -EPERM;
timens_commit(current, ns);
get_time_ns(ns);
put_time_ns(nsproxy->time_ns);
nsproxy->time_ns = ns;