// SPDX-License-Identifier: GPL-2.0/* * Author: Andrei Vagin <avagin@openvz.org> * Author: Dmitry Safonov <dima@arista.com> */ #include <linux/time_namespace.h>#include <linux/user_namespace.h>#include <linux/sched/signal.h>#include <linux/sched/task.h>#include <linux/clocksource.h>#include <linux/seq_file.h>#include <linux/proc_ns.h>#include <linux/export.h>#include <linux/time.h>#include <linux/slab.h>#include <linux/cred.h>#include <linux/err.h>#include <linux/mm.h> #include <vdso/datapage.h> ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,				struct timens_offsets *ns_offsets){	ktime_t offset; 	switch (clockid) {	case CLOCK_MONOTONIC:		offset = timespec64_to_ktime(ns_offsets->monotonic);		break;	case CLOCK_BOOTTIME:	case CLOCK_BOOTTIME_ALARM:		offset = timespec64_to_ktime(ns_offsets->boottime);		break;	default:		return tim;	} 	/*	 * Check that @tim value is in [offset, KTIME_MAX + offset]	 * and subtract offset.	 */	if (tim < offset) {		/*		 * User can specify @tim *absolute* value - if it's lesser than		 * the time namespace's offset - it's already expired.		 */		tim = 0;	} else {		tim = ktime_sub(tim, offset);		if (unlikely(tim > KTIME_MAX))			tim = KTIME_MAX;	} 	return tim;} static struct ucounts *inc_time_namespaces(struct user_namespace *ns){	return inc_ucount(ns, current_euid(), UCOUNT_TIME_NAMESPACES);} static void dec_time_namespaces(struct ucounts *ucounts){	dec_ucount(ucounts, UCOUNT_TIME_NAMESPACES);} /** * clone_time_ns - Clone a time namespace * @user_ns:	User namespace which owns a new namespace. * @old_ns:	Namespace to clone * * Clone @old_ns and set the clone refcount to 1 * * Return: The new namespace or ERR_PTR. */static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,					  struct time_namespace *old_ns){	struct time_namespace *ns;	struct ucounts *ucounts;	int err; 	err = -ENOSPC;	ucounts = inc_time_namespaces(user_ns);	if (!ucounts)		goto fail; 	err = -ENOMEM;	ns = kmalloc(sizeof(*ns), GFP_KERNEL_ACCOUNT);	if (!ns)		goto fail_dec; 	refcount_set(&ns->ns.count, 1); 	ns->vvar_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);	if (!ns->vvar_page)		goto fail_free; 	err = ns_alloc_inum(&ns->ns);	if (err)		goto fail_free_page; 	ns->ucounts = ucounts;	ns->ns.ops = &timens_operations;	ns->user_ns = get_user_ns(user_ns);	ns->offsets = old_ns->offsets;	ns->frozen_offsets = false;	return ns; fail_free_page:	__free_page(ns->vvar_page);fail_free:	kfree(ns);fail_dec:	dec_time_namespaces(ucounts);fail:	return ERR_PTR(err);} /** * copy_time_ns - Create timens_for_children from @old_ns * @flags:	Cloning flags * @user_ns:	User namespace which owns a new namespace. * @old_ns:	Namespace to clone * * If CLONE_NEWTIME specified in @flags, creates a new timens_for_children; * adds a refcounter to @old_ns otherwise. * * Return: timens_for_children namespace or ERR_PTR. */struct time_namespace *copy_time_ns(unsigned long flags,	struct user_namespace *user_ns, struct time_namespace *old_ns){	if (!(flags & CLONE_NEWTIME))		return get_time_ns(old_ns); 	return clone_time_ns(user_ns, old_ns);} static struct timens_offset offset_from_ts(struct timespec64 off){	struct timens_offset ret; 	ret.sec = off.tv_sec;	ret.nsec = off.tv_nsec; 	return ret;} /* * A time namespace VVAR page has the same layout as the VVAR page which * contains the system wide VDSO data. * * For a normal task the VVAR pages are installed in the normal ordering: *     VVAR *     PVCLOCK *     HVCLOCK *     TIMENS   <- Not really required * * Now for a timens task the pages are installed in the following order: *     TIMENS *     PVCLOCK *     HVCLOCK *     VVAR * * The check for vdso_data->clock_mode is in the unlikely path of * the seq begin magic. So for the non-timens case most of the time * 'seq' is even, so the branch is not taken. * * If 'seq' is odd, i.e. a concurrent update is in progress, the extra check * for vdso_data->clock_mode is a non-issue. The task is spin waiting for the * update to finish and for 'seq' to become even anyway. * * Timens page has vdso_data->clock_mode set to VDSO_CLOCKMODE_TIMENS which * enforces the time namespace handling path. */static void timens_setup_vdso_data(struct vdso_data *vdata,				   struct time_namespace *ns){	struct timens_offset *offset = vdata->offset;	struct timens_offset monotonic = offset_from_ts(ns->offsets.monotonic);	struct timens_offset boottime = offset_from_ts(ns->offsets.boottime); 	vdata->seq			= 1;	vdata->clock_mode		= VDSO_CLOCKMODE_TIMENS;	offset[CLOCK_MONOTONIC]		= monotonic;	offset[CLOCK_MONOTONIC_RAW]	= monotonic;	offset[CLOCK_MONOTONIC_COARSE]	= monotonic;	offset[CLOCK_BOOTTIME]		= boottime;	offset[CLOCK_BOOTTIME_ALARM]	= boottime;} struct page *find_timens_vvar_page(struct vm_area_struct *vma){	if (likely(vma->vm_mm == current->mm))		return current->nsproxy->time_ns->vvar_page; 	/*	 * VM_PFNMAP | VM_IO protect .fault() handler from being called	 * through interfaces like /proc/$pid/mem or	 * process_vm_{readv,writev}() as long as there's no .access()	 * in special_mapping_vmops().	 * For more details check_vma_flags() and __access_remote_vm()	 */ 	WARN(1, "vvar_page accessed remotely"); 	return NULL;} /* * Protects possibly multiple offsets writers racing each other * and tasks entering the namespace. */static DEFINE_MUTEX(offset_lock); static void timens_set_vvar_page(struct task_struct *task,				struct time_namespace *ns){	struct vdso_data *vdata;	unsigned int i; 	if (ns == &init_time_ns)		return; 	/* Fast-path, taken by every task in namespace except the first. */	if (likely(ns->frozen_offsets))		return; 	mutex_lock(&offset_lock);	/* Nothing to-do: vvar_page has been already initialized. */	if (ns->frozen_offsets)		goto out; 	ns->frozen_offsets = true;	vdata = arch_get_vdso_data(page_address(ns->vvar_page)); 	for (i = 0; i < CS_BASES; i++)		timens_setup_vdso_data(&vdata[i], ns); out:	mutex_unlock(&offset_lock);} void free_time_ns(struct time_namespace *ns){	dec_time_namespaces(ns->ucounts);	put_user_ns(ns->user_ns);	ns_free_inum(&ns->ns);	__free_page(ns->vvar_page);	kfree(ns);} static struct time_namespace *to_time_ns(struct ns_common *ns){	return container_of(ns, struct time_namespace, ns);} static struct ns_common *timens_get(struct task_struct *task){	struct time_namespace *ns = NULL;	struct nsproxy *nsproxy; 	task_lock(task);	nsproxy = task->nsproxy;	if (nsproxy) {		ns = nsproxy->time_ns;		get_time_ns(ns);	}	task_unlock(task); 	return ns ? &ns->ns : NULL;} static struct ns_common *timens_for_children_get(struct task_struct *task){	struct time_namespace *ns = NULL;	struct nsproxy *nsproxy; 	task_lock(task);	nsproxy = task->nsproxy;	if (nsproxy) {		ns = nsproxy->time_ns_for_children;		get_time_ns(ns);	}	task_unlock(task); 	return ns ? &ns->ns : NULL;} static void timens_put(struct ns_common *ns){	put_time_ns(to_time_ns(ns));} void timens_commit(struct task_struct *tsk, struct time_namespace *ns){	timens_set_vvar_page(tsk, ns);	vdso_join_timens(tsk, ns);} static int timens_install(struct nsset *nsset, struct ns_common *new){	struct nsproxy *nsproxy = nsset->nsproxy;	struct time_namespace *ns = to_time_ns(new); 	if (!current_is_single_threaded())		return -EUSERS; 	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))		return -EPERM; 	get_time_ns(ns);	put_time_ns(nsproxy->time_ns);	nsproxy->time_ns = ns; 	get_time_ns(ns);	put_time_ns(nsproxy->time_ns_for_children);	nsproxy->time_ns_for_children = ns;	return 0;} void timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk){	struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;	struct time_namespace *ns = to_time_ns(nsc); 	/* create_new_namespaces() already incremented the ref counter */	if (nsproxy->time_ns == nsproxy->time_ns_for_children)		return; 	get_time_ns(ns);	put_time_ns(nsproxy->time_ns);	nsproxy->time_ns = ns; 	timens_commit(tsk, ns);} static struct user_namespace *timens_owner(struct ns_common *ns){	return to_time_ns(ns)->user_ns;} static void show_offset(struct seq_file *m, int clockid, struct timespec64 *ts){	char *clock; 	switch (clockid) {	case CLOCK_BOOTTIME:		clock = "boottime";		break;	case CLOCK_MONOTONIC:		clock = "monotonic";		break;	default:		clock = "unknown";		break;	}	seq_printf(m, "%-10s %10lld %9ld\n", clock, ts->tv_sec, ts->tv_nsec);} void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m){	struct ns_common *ns;	struct time_namespace *time_ns; 	ns = timens_for_children_get(p);	if (!ns)		return;	time_ns = to_time_ns(ns); 	show_offset(m, CLOCK_MONOTONIC, &time_ns->offsets.monotonic);	show_offset(m, CLOCK_BOOTTIME, &time_ns->offsets.boottime);	put_time_ns(time_ns);} int proc_timens_set_offset(struct file *file, struct task_struct *p,			   struct proc_timens_offset *offsets, int noffsets){	struct ns_common *ns;	struct time_namespace *time_ns;	struct timespec64 tp;	int i, err; 	ns = timens_for_children_get(p);	if (!ns)		return -ESRCH;	time_ns = to_time_ns(ns); 	if (!file_ns_capable(file, time_ns->user_ns, CAP_SYS_TIME)) {		put_time_ns(time_ns);		return -EPERM;	} 	for (i = 0; i < noffsets; i++) {		struct proc_timens_offset *off = &offsets[i]; 		switch (off->clockid) {		case CLOCK_MONOTONIC:			ktime_get_ts64(&tp);			break;		case CLOCK_BOOTTIME:			ktime_get_boottime_ts64(&tp);			break;		default:			err = -EINVAL;			goto out;		} 		err = -ERANGE; 		if (off->val.tv_sec > KTIME_SEC_MAX ||		    off->val.tv_sec < -KTIME_SEC_MAX)			goto out; 		tp = timespec64_add(tp, off->val);		/*		 * KTIME_SEC_MAX is divided by 2 to be sure that KTIME_MAX is		 * still unreachable.		 */		if (tp.tv_sec < 0 || tp.tv_sec > KTIME_SEC_MAX / 2)			goto out;	} 	mutex_lock(&offset_lock);	if (time_ns->frozen_offsets) {		err = -EACCES;		goto out_unlock;	} 	err = 0;	/* Don't report errors after this line */	for (i = 0; i < noffsets; i++) {		struct proc_timens_offset *off = &offsets[i];		struct timespec64 *offset = NULL; 		switch (off->clockid) {		case CLOCK_MONOTONIC:			offset = &time_ns->offsets.monotonic;			break;		case CLOCK_BOOTTIME:			offset = &time_ns->offsets.boottime;			break;		} 		*offset = off->val;	} out_unlock:	mutex_unlock(&offset_lock);out:	put_time_ns(time_ns); 	return err;} const struct proc_ns_operations timens_operations = {	.name		= "time",	.type		= CLONE_NEWTIME,	.get		= timens_get,	.put		= timens_put,	.install	= timens_install,	.owner		= timens_owner,}; const struct proc_ns_operations timens_for_children_operations = {	.name		= "time_for_children",	.real_ns_name	= "time",	.type		= CLONE_NEWTIME,	.get		= timens_for_children_get,	.put		= timens_put,	.install	= timens_install,	.owner		= timens_owner,}; struct time_namespace init_time_ns = {	.ns.count	= REFCOUNT_INIT(3),	.user_ns	= &init_user_ns,	.ns.inum	= PROC_TIME_INIT_INO,	.ns.ops		= &timens_operations,	.frozen_offsets	= true,};