mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-28 22:54:05 +08:00
b9dd04a20f
KFENCE requires linear map to be mapped at page granularity, so that it is possible to protect/unprotect single pages, just like with rodata_full and DEBUG_PAGEALLOC. Instead of repating can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE) make can_set_direct_map() handle the KFENCE case. This also prevents potential false positives in kernel_page_present() that may return true for non-present page if CONFIG_KFENCE is enabled. Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Link: https://lore.kernel.org/r/20220921074841.382615-1-rppt@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
248 lines
6.1 KiB
C
248 lines
6.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* Copyright (c) 2014, The Linux Foundation. All rights reserved.
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/module.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/vmalloc.h>
|
|
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/set_memory.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
struct page_change_data {
|
|
pgprot_t set_mask;
|
|
pgprot_t clear_mask;
|
|
};
|
|
|
|
bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED);
|
|
|
|
bool can_set_direct_map(void)
|
|
{
|
|
/*
|
|
* rodata_full, DEBUG_PAGEALLOC and KFENCE require linear map to be
|
|
* mapped at page granularity, so that it is possible to
|
|
* protect/unprotect single pages.
|
|
*/
|
|
return rodata_full || debug_pagealloc_enabled() ||
|
|
IS_ENABLED(CONFIG_KFENCE);
|
|
}
|
|
|
|
static int change_page_range(pte_t *ptep, unsigned long addr, void *data)
|
|
{
|
|
struct page_change_data *cdata = data;
|
|
pte_t pte = READ_ONCE(*ptep);
|
|
|
|
pte = clear_pte_bit(pte, cdata->clear_mask);
|
|
pte = set_pte_bit(pte, cdata->set_mask);
|
|
|
|
set_pte(ptep, pte);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This function assumes that the range is mapped with PAGE_SIZE pages.
|
|
*/
|
|
static int __change_memory_common(unsigned long start, unsigned long size,
|
|
pgprot_t set_mask, pgprot_t clear_mask)
|
|
{
|
|
struct page_change_data data;
|
|
int ret;
|
|
|
|
data.set_mask = set_mask;
|
|
data.clear_mask = clear_mask;
|
|
|
|
ret = apply_to_page_range(&init_mm, start, size, change_page_range,
|
|
&data);
|
|
|
|
flush_tlb_kernel_range(start, start + size);
|
|
return ret;
|
|
}
|
|
|
|
static int change_memory_common(unsigned long addr, int numpages,
|
|
pgprot_t set_mask, pgprot_t clear_mask)
|
|
{
|
|
unsigned long start = addr;
|
|
unsigned long size = PAGE_SIZE * numpages;
|
|
unsigned long end = start + size;
|
|
struct vm_struct *area;
|
|
int i;
|
|
|
|
if (!PAGE_ALIGNED(addr)) {
|
|
start &= PAGE_MASK;
|
|
end = start + size;
|
|
WARN_ON_ONCE(1);
|
|
}
|
|
|
|
/*
|
|
* Kernel VA mappings are always live, and splitting live section
|
|
* mappings into page mappings may cause TLB conflicts. This means
|
|
* we have to ensure that changing the permission bits of the range
|
|
* we are operating on does not result in such splitting.
|
|
*
|
|
* Let's restrict ourselves to mappings created by vmalloc (or vmap).
|
|
* Those are guaranteed to consist entirely of page mappings, and
|
|
* splitting is never needed.
|
|
*
|
|
* So check whether the [addr, addr + size) interval is entirely
|
|
* covered by precisely one VM area that has the VM_ALLOC flag set.
|
|
*/
|
|
area = find_vm_area((void *)addr);
|
|
if (!area ||
|
|
end > (unsigned long)kasan_reset_tag(area->addr) + area->size ||
|
|
!(area->flags & VM_ALLOC))
|
|
return -EINVAL;
|
|
|
|
if (!numpages)
|
|
return 0;
|
|
|
|
/*
|
|
* If we are manipulating read-only permissions, apply the same
|
|
* change to the linear mapping of the pages that back this VM area.
|
|
*/
|
|
if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
|
|
pgprot_val(clear_mask) == PTE_RDONLY)) {
|
|
for (i = 0; i < area->nr_pages; i++) {
|
|
__change_memory_common((u64)page_address(area->pages[i]),
|
|
PAGE_SIZE, set_mask, clear_mask);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Get rid of potentially aliasing lazily unmapped vm areas that may
|
|
* have permissions set that deviate from the ones we are setting here.
|
|
*/
|
|
vm_unmap_aliases();
|
|
|
|
return __change_memory_common(start, size, set_mask, clear_mask);
|
|
}
|
|
|
|
int set_memory_ro(unsigned long addr, int numpages)
|
|
{
|
|
return change_memory_common(addr, numpages,
|
|
__pgprot(PTE_RDONLY),
|
|
__pgprot(PTE_WRITE));
|
|
}
|
|
|
|
int set_memory_rw(unsigned long addr, int numpages)
|
|
{
|
|
return change_memory_common(addr, numpages,
|
|
__pgprot(PTE_WRITE),
|
|
__pgprot(PTE_RDONLY));
|
|
}
|
|
|
|
int set_memory_nx(unsigned long addr, int numpages)
|
|
{
|
|
return change_memory_common(addr, numpages,
|
|
__pgprot(PTE_PXN),
|
|
__pgprot(PTE_MAYBE_GP));
|
|
}
|
|
|
|
int set_memory_x(unsigned long addr, int numpages)
|
|
{
|
|
return change_memory_common(addr, numpages,
|
|
__pgprot(PTE_MAYBE_GP),
|
|
__pgprot(PTE_PXN));
|
|
}
|
|
|
|
int set_memory_valid(unsigned long addr, int numpages, int enable)
|
|
{
|
|
if (enable)
|
|
return __change_memory_common(addr, PAGE_SIZE * numpages,
|
|
__pgprot(PTE_VALID),
|
|
__pgprot(0));
|
|
else
|
|
return __change_memory_common(addr, PAGE_SIZE * numpages,
|
|
__pgprot(0),
|
|
__pgprot(PTE_VALID));
|
|
}
|
|
|
|
int set_direct_map_invalid_noflush(struct page *page)
|
|
{
|
|
struct page_change_data data = {
|
|
.set_mask = __pgprot(0),
|
|
.clear_mask = __pgprot(PTE_VALID),
|
|
};
|
|
|
|
if (!can_set_direct_map())
|
|
return 0;
|
|
|
|
return apply_to_page_range(&init_mm,
|
|
(unsigned long)page_address(page),
|
|
PAGE_SIZE, change_page_range, &data);
|
|
}
|
|
|
|
int set_direct_map_default_noflush(struct page *page)
|
|
{
|
|
struct page_change_data data = {
|
|
.set_mask = __pgprot(PTE_VALID | PTE_WRITE),
|
|
.clear_mask = __pgprot(PTE_RDONLY),
|
|
};
|
|
|
|
if (!can_set_direct_map())
|
|
return 0;
|
|
|
|
return apply_to_page_range(&init_mm,
|
|
(unsigned long)page_address(page),
|
|
PAGE_SIZE, change_page_range, &data);
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_PAGEALLOC
|
|
void __kernel_map_pages(struct page *page, int numpages, int enable)
|
|
{
|
|
if (!can_set_direct_map())
|
|
return;
|
|
|
|
set_memory_valid((unsigned long)page_address(page), numpages, enable);
|
|
}
|
|
#endif /* CONFIG_DEBUG_PAGEALLOC */
|
|
|
|
/*
|
|
* This function is used to determine if a linear map page has been marked as
|
|
* not-valid. Walk the page table and check the PTE_VALID bit. This is based
|
|
* on kern_addr_valid(), which almost does what we need.
|
|
*
|
|
* Because this is only called on the kernel linear map, p?d_sect() implies
|
|
* p?d_present(). When debug_pagealloc is enabled, sections mappings are
|
|
* disabled.
|
|
*/
|
|
bool kernel_page_present(struct page *page)
|
|
{
|
|
pgd_t *pgdp;
|
|
p4d_t *p4dp;
|
|
pud_t *pudp, pud;
|
|
pmd_t *pmdp, pmd;
|
|
pte_t *ptep;
|
|
unsigned long addr = (unsigned long)page_address(page);
|
|
|
|
if (!can_set_direct_map())
|
|
return true;
|
|
|
|
pgdp = pgd_offset_k(addr);
|
|
if (pgd_none(READ_ONCE(*pgdp)))
|
|
return false;
|
|
|
|
p4dp = p4d_offset(pgdp, addr);
|
|
if (p4d_none(READ_ONCE(*p4dp)))
|
|
return false;
|
|
|
|
pudp = pud_offset(p4dp, addr);
|
|
pud = READ_ONCE(*pudp);
|
|
if (pud_none(pud))
|
|
return false;
|
|
if (pud_sect(pud))
|
|
return true;
|
|
|
|
pmdp = pmd_offset(pudp, addr);
|
|
pmd = READ_ONCE(*pmdp);
|
|
if (pmd_none(pmd))
|
|
return false;
|
|
if (pmd_sect(pmd))
|
|
return true;
|
|
|
|
ptep = pte_offset_kernel(pmdp, addr);
|
|
return pte_valid(READ_ONCE(*ptep));
|
|
}
|