/*
 *  Copyright (C) 2004 IBM Corporation
 *
 *  Author: Serge Hallyn <serue@us.ibm.com>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as
 *  published by the Free Software Foundation, version 2 of the
 *  License.
 */

#include <linux/export.h>
#include <linux/uts.h>
#include <linux/utsname.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>
#include <linux/proc_ns.h>

static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
{
	return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
}

static void dec_uts_namespaces(struct ucounts *ucounts)
{
	dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES);
}

static struct uts_namespace *create_uts_ns(void)
{
	struct uts_namespace *uts_ns;

	uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
	if (uts_ns)
		kref_init(&uts_ns->kref);
	return uts_ns;
}

/*
 * Clone a new ns copying an original utsname, setting refcount to 1
 * @old_ns: namespace to clone
 * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
 */
static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
					  struct uts_namespace *old_ns)
{
	struct uts_namespace *ns;
	struct ucounts *ucounts;
	int err;

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

	err = -ENOMEM;
	ns = create_uts_ns();
	if (!ns)
		goto fail_dec;

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

	ns->ucounts = ucounts;
	ns->ns.ops = &utsns_operations;

	down_read(&uts_sem);
	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
	ns->user_ns = get_user_ns(user_ns);
	up_read(&uts_sem);
	return ns;

fail_free:
	kfree(ns);
fail_dec:
	dec_uts_namespaces(ucounts);
fail:
	return ERR_PTR(err);
}

/*
 * Copy task tsk's utsname namespace, or clone it if flags
 * specifies CLONE_NEWUTS.  In latter case, changes to the
 * utsname of this process won't be seen by parent, and vice
 * versa.
 */
struct uts_namespace *copy_utsname(unsigned long flags,
	struct user_namespace *user_ns, struct uts_namespace *old_ns)
{
	struct uts_namespace *new_ns;

	BUG_ON(!old_ns);
	get_uts_ns(old_ns);

	if (!(flags & CLONE_NEWUTS))
		return old_ns;

	new_ns = clone_uts_ns(user_ns, old_ns);

	put_uts_ns(old_ns);
	return new_ns;
}

void free_uts_ns(struct kref *kref)
{
	struct uts_namespace *ns;

	ns = container_of(kref, struct uts_namespace, kref);
	dec_uts_namespaces(ns->ucounts);
	put_user_ns(ns->user_ns);
	ns_free_inum(&ns->ns);
	kfree(ns);
}

static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
{
	return container_of(ns, struct uts_namespace, ns);
}

static struct ns_common *utsns_get(struct task_struct *task)
{
	struct uts_namespace *ns = NULL;
	struct nsproxy *nsproxy;

	task_lock(task);
	nsproxy = task->nsproxy;
	if (nsproxy) {
		ns = nsproxy->uts_ns;
		get_uts_ns(ns);
	}
	task_unlock(task);

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

static void utsns_put(struct ns_common *ns)
{
	put_uts_ns(to_uts_ns(ns));
}

static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
{
	struct uts_namespace *ns = to_uts_ns(new);

	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
		return -EPERM;

	get_uts_ns(ns);
	put_uts_ns(nsproxy->uts_ns);
	nsproxy->uts_ns = ns;
	return 0;
}

static struct user_namespace *utsns_owner(struct ns_common *ns)
{
	return to_uts_ns(ns)->user_ns;
}

const struct proc_ns_operations utsns_operations = {
	.name		= "uts",
	.type		= CLONE_NEWUTS,
	.get		= utsns_get,
	.put		= utsns_put,
	.install	= utsns_install,
	.owner		= utsns_owner,
};
value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;</td><td class='right'>2017-02-01 17:45:02 +0000</td></tr>
<tr><th>committer</th><td>Ingo Molnar &lt;mingo@kernel.org&gt;</td><td class='right'>2017-02-01 21:17:49 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/9p/xattr.h?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>c8f325a59cfc718d13a50fbc746ed9b415c25e92</a> (<a href='/cgit.cgi/linux/net-next.git/patch/fs/9p/xattr.h?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>d53fbdac9d0781e39a13b2ac6b2bd258cf3b4140</a> /<a href='/cgit.cgi/linux/net-next.git/tree/fs/9p/xattr.h?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>fs/9p/xattr.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/9p/xattr.h?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>bf29bddf0417a4783da3b24e8c9e017ac649326f</a> (<a href='/cgit.cgi/linux/net-next.git/diff/fs/9p/xattr.h?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92&amp;id2=bf29bddf0417a4783da3b24e8c9e017ac649326f'>diff</a>)</td></tr></table>
<div class='commit-subject'>efi/fdt: Avoid FDT manipulation after ExitBootServices()</div><div class='commit-msg'>Some AArch64 UEFI implementations disable the MMU in ExitBootServices(),
after which unaligned accesses to RAM are no longer supported.

Commit:

  abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")

fixed an issue in the memory map handling of the stub FDT code, but
inadvertently created an issue with such firmware, by moving some
of the FDT manipulation to after the invocation of ExitBootServices().

Given that the stub's libfdt implementation uses the ordinary, accelerated
string functions, which rely on hardware handling of unaligned accesses,
manipulating the FDT with the MMU off may result in alignment faults.

So fix the situation by moving the update_fdt_memmap() call into the
callback function invoked by efi_exit_boot_services() right before it
calls the ExitBootServices() UEFI service (which is arguably a better
place for it anyway)

Note that disabling the MMU in ExitBootServices() is not compliant with
the UEFI spec, and carries great risk due to the fact that switching from
cached to uncached memory accesses halfway through compiler generated code
(i.e., involving a stack) can never be done in a way that is architecturally
safe.

Fixes: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Tested-by: Riku Voipio &lt;riku.voipio@linaro.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Cc: mark.rutland@arm.com
Cc: linux-efi@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: leif.lindholm@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>Diffstat</a> (limited to 'fs/9p/xattr.h')</div><table summary='diffstat' class='diffstat'>