Revision 5f56a74cc0a6d9b9f8ba89cea29cd7c4774cb2b1 authored by Ard Biesheuvel on 20 September 2022, 15:08:23 UTC, committed by Ard Biesheuvel on 22 September 2022, 08:15:44 UTC
We currently check the MokSBState variable to decide whether we should
treat UEFI secure boot as being disabled, even if the firmware thinks
otherwise. This is used by shim to indicate that it is not checking
signatures on boot images. In the kernel, we use this to relax lockdown
policies.

However, in cases where shim is not even being used, we don't want this
variable to interfere with lockdown, given that the variable may be
non-volatile and therefore persist across a reboot. This means setting
it once will persistently disable lockdown checks on a given system.

So switch to the mirrored version of this variable, called MokSBStateRT,
which is supposed to be volatile, and this is something we can check.

Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Peter Jones <pjones@redhat.com>
1 parent 63bf28c
Raw File
folio-compat.c
/*
 * Compatibility functions which bloat the callers too much to make inline.
 * All of the callers of these functions should be converted to use folios
 * eventually.
 */

#include <linux/migrate.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include "internal.h"

struct address_space *page_mapping(struct page *page)
{
	return folio_mapping(page_folio(page));
}
EXPORT_SYMBOL(page_mapping);

void unlock_page(struct page *page)
{
	return folio_unlock(page_folio(page));
}
EXPORT_SYMBOL(unlock_page);

void end_page_writeback(struct page *page)
{
	return folio_end_writeback(page_folio(page));
}
EXPORT_SYMBOL(end_page_writeback);

void wait_on_page_writeback(struct page *page)
{
	return folio_wait_writeback(page_folio(page));
}
EXPORT_SYMBOL_GPL(wait_on_page_writeback);

void wait_for_stable_page(struct page *page)
{
	return folio_wait_stable(page_folio(page));
}
EXPORT_SYMBOL_GPL(wait_for_stable_page);

bool page_mapped(struct page *page)
{
	return folio_mapped(page_folio(page));
}
EXPORT_SYMBOL(page_mapped);

void mark_page_accessed(struct page *page)
{
	folio_mark_accessed(page_folio(page));
}
EXPORT_SYMBOL(mark_page_accessed);

bool set_page_writeback(struct page *page)
{
	return folio_start_writeback(page_folio(page));
}
EXPORT_SYMBOL(set_page_writeback);

bool set_page_dirty(struct page *page)
{
	return folio_mark_dirty(page_folio(page));
}
EXPORT_SYMBOL(set_page_dirty);

int __set_page_dirty_nobuffers(struct page *page)
{
	return filemap_dirty_folio(page_mapping(page), page_folio(page));
}
EXPORT_SYMBOL(__set_page_dirty_nobuffers);

bool clear_page_dirty_for_io(struct page *page)
{
	return folio_clear_dirty_for_io(page_folio(page));
}
EXPORT_SYMBOL(clear_page_dirty_for_io);

bool redirty_page_for_writepage(struct writeback_control *wbc,
		struct page *page)
{
	return folio_redirty_for_writepage(wbc, page_folio(page));
}
EXPORT_SYMBOL(redirty_page_for_writepage);

void lru_cache_add(struct page *page)
{
	folio_add_lru(page_folio(page));
}
EXPORT_SYMBOL(lru_cache_add);

int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
		pgoff_t index, gfp_t gfp)
{
	return filemap_add_folio(mapping, page_folio(page), index, gfp);
}
EXPORT_SYMBOL(add_to_page_cache_lru);

noinline
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
		int fgp_flags, gfp_t gfp)
{
	struct folio *folio;

	folio = __filemap_get_folio(mapping, index, fgp_flags, gfp);
	if ((fgp_flags & FGP_HEAD) || !folio || xa_is_value(folio))
		return &folio->page;
	return folio_file_page(folio, index);
}
EXPORT_SYMBOL(pagecache_get_page);

struct page *grab_cache_page_write_begin(struct address_space *mapping,
					pgoff_t index)
{
	unsigned fgp_flags = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE;

	return pagecache_get_page(mapping, index, fgp_flags,
			mapping_gfp_mask(mapping));
}
EXPORT_SYMBOL(grab_cache_page_write_begin);

void delete_from_page_cache(struct page *page)
{
	return filemap_remove_folio(page_folio(page));
}

int try_to_release_page(struct page *page, gfp_t gfp)
{
	return filemap_release_folio(page_folio(page), gfp);
}
EXPORT_SYMBOL(try_to_release_page);

int isolate_lru_page(struct page *page)
{
	if (WARN_RATELIMIT(PageTail(page), "trying to isolate tail page"))
		return -EBUSY;
	return folio_isolate_lru((struct folio *)page);
}

void putback_lru_page(struct page *page)
{
	folio_putback_lru(page_folio(page));
}
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