Revision 0273fd423b2fe10af96ff713273137c63a7736c0 authored by Linus Torvalds on 21 June 2022, 17:13:53 UTC, committed by Linus Torvalds on 21 June 2022, 17:13:53 UTC
Pull signature checking selftest from David Howells:
 "The signature checking code, as used by module signing, kexec, etc.,
  is non-FIPS compliant as there is no selftest.

  For a kernel to be FIPS-compliant, signature checking would have to be
  tested before being used, and the box would need to panic if it's not
  available (probably reasonable as simply disabling signature checking
  would prevent you from loading any driver modules).

  Deal with this by adding a minimal test.

  This is split into two patches: the first moves load_certificate_list()
  to the same place as the X.509 code to make it more accessible
  internally; the second adds a selftest"

* tag 'certs-20220621' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  certs: Add FIPS selftests
  certs: Move load_certificate_list() to be with the asymmetric keys code
2 parent s ff872b7 + 3cde317
Raw File
namespace.c
// SPDX-License-Identifier: GPL-2.0
/*
 * linux/ipc/namespace.c
 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
 */

#include <linux/ipc.h>
#include <linux/msg.h>
#include <linux/ipc_namespace.h>
#include <linux/rcupdate.h>
#include <linux/nsproxy.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/user_namespace.h>
#include <linux/proc_ns.h>
#include <linux/sched/task.h>

#include "util.h"

static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
{
	return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
}

static void dec_ipc_namespaces(struct ucounts *ucounts)
{
	dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
}

static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
					   struct ipc_namespace *old_ns)
{
	struct ipc_namespace *ns;
	struct ucounts *ucounts;
	int err;

	err = -ENOSPC;
	ucounts = inc_ipc_namespaces(user_ns);
	if (!ucounts)
		goto fail;

	err = -ENOMEM;
	ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL_ACCOUNT);
	if (ns == NULL)
		goto fail_dec;

	err = ns_alloc_inum(&ns->ns);
	if (err)
		goto fail_free;
	ns->ns.ops = &ipcns_operations;

	refcount_set(&ns->ns.count, 1);
	ns->user_ns = get_user_ns(user_ns);
	ns->ucounts = ucounts;

	err = mq_init_ns(ns);
	if (err)
		goto fail_put;

	err = -ENOMEM;
	if (!setup_mq_sysctls(ns))
		goto fail_put;

	if (!setup_ipc_sysctls(ns))
		goto fail_put;

	sem_init_ns(ns);
	msg_init_ns(ns);
	shm_init_ns(ns);

	return ns;

fail_put:
	put_user_ns(ns->user_ns);
	ns_free_inum(&ns->ns);
fail_free:
	kfree(ns);
fail_dec:
	dec_ipc_namespaces(ucounts);
fail:
	return ERR_PTR(err);
}

struct ipc_namespace *copy_ipcs(unsigned long flags,
	struct user_namespace *user_ns, struct ipc_namespace *ns)
{
	if (!(flags & CLONE_NEWIPC))
		return get_ipc_ns(ns);
	return create_ipc_ns(user_ns, ns);
}

/*
 * free_ipcs - free all ipcs of one type
 * @ns:   the namespace to remove the ipcs from
 * @ids:  the table of ipcs to free
 * @free: the function called to free each individual ipc
 *
 * Called for each kind of ipc when an ipc_namespace exits.
 */
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
{
	struct kern_ipc_perm *perm;
	int next_id;
	int total, in_use;

	down_write(&ids->rwsem);

	in_use = ids->in_use;

	for (total = 0, next_id = 0; total < in_use; next_id++) {
		perm = idr_find(&ids->ipcs_idr, next_id);
		if (perm == NULL)
			continue;
		rcu_read_lock();
		ipc_lock_object(perm);
		free(ns, perm);
		total++;
	}
	up_write(&ids->rwsem);
}

static void free_ipc_ns(struct ipc_namespace *ns)
{
	/* mq_put_mnt() waits for a grace period as kern_unmount()
	 * uses synchronize_rcu().
	 */
	mq_put_mnt(ns);
	sem_exit_ns(ns);
	msg_exit_ns(ns);
	shm_exit_ns(ns);

	retire_mq_sysctls(ns);
	retire_ipc_sysctls(ns);

	dec_ipc_namespaces(ns->ucounts);
	put_user_ns(ns->user_ns);
	ns_free_inum(&ns->ns);
	kfree(ns);
}

static LLIST_HEAD(free_ipc_list);
static void free_ipc(struct work_struct *unused)
{
	struct llist_node *node = llist_del_all(&free_ipc_list);
	struct ipc_namespace *n, *t;

	llist_for_each_entry_safe(n, t, node, mnt_llist)
		free_ipc_ns(n);
}

/*
 * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
 */
static DECLARE_WORK(free_ipc_work, free_ipc);

/*
 * put_ipc_ns - drop a reference to an ipc namespace.
 * @ns: the namespace to put
 *
 * If this is the last task in the namespace exiting, and
 * it is dropping the refcount to 0, then it can race with
 * a task in another ipc namespace but in a mounts namespace
 * which has this ipcns's mqueuefs mounted, doing some action
 * with one of the mqueuefs files.  That can raise the refcount.
 * So dropping the refcount, and raising the refcount when
 * accessing it through the VFS, are protected with mq_lock.
 *
 * (Clearly, a task raising the refcount on its own ipc_ns
 * needn't take mq_lock since it can't race with the last task
 * in the ipcns exiting).
 */
void put_ipc_ns(struct ipc_namespace *ns)
{
	if (refcount_dec_and_lock(&ns->ns.count, &mq_lock)) {
		mq_clear_sbinfo(ns);
		spin_unlock(&mq_lock);

		if (llist_add(&ns->mnt_llist, &free_ipc_list))
			schedule_work(&free_ipc_work);
	}
}

static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
{
	return container_of(ns, struct ipc_namespace, ns);
}

static struct ns_common *ipcns_get(struct task_struct *task)
{
	struct ipc_namespace *ns = NULL;
	struct nsproxy *nsproxy;

	task_lock(task);
	nsproxy = task->nsproxy;
	if (nsproxy)
		ns = get_ipc_ns(nsproxy->ipc_ns);
	task_unlock(task);

	return ns ? &ns->ns : NULL;
}

static void ipcns_put(struct ns_common *ns)
{
	return put_ipc_ns(to_ipc_ns(ns));
}

static int ipcns_install(struct nsset *nsset, struct ns_common *new)
{
	struct nsproxy *nsproxy = nsset->nsproxy;
	struct ipc_namespace *ns = to_ipc_ns(new);
	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
		return -EPERM;

	put_ipc_ns(nsproxy->ipc_ns);
	nsproxy->ipc_ns = get_ipc_ns(ns);
	return 0;
}

static struct user_namespace *ipcns_owner(struct ns_common *ns)
{
	return to_ipc_ns(ns)->user_ns;
}

const struct proc_ns_operations ipcns_operations = {
	.name		= "ipc",
	.type		= CLONE_NEWIPC,
	.get		= ipcns_get,
	.put		= ipcns_put,
	.install	= ipcns_install,
	.owner		= ipcns_owner,
};
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