[RFC PATCH 10/16] mm: Map page tables with privileged pkey
From: Kevin Brodsky <hidden>
Date: 2024-12-06 10:13:45
Also in:
linux-hardening, lkml
Subsystem:
memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
If CONFIG_KPKEYS_HARDENED_PGTABLES is enabled, map allocated page table pages using a privileged pkey (KPKEYS_PKEY_PGTABLES), so that page tables can only be written under guard(kpkeys_hardened_pgtables). This patch is a no-op if CONFIG_KPKEYS_HARDENED_PGTABLES is disabled (default). Signed-off-by: Kevin Brodsky <redacted> --- include/linux/mm.h | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 683e883dae77..4fb25454ba85 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -31,6 +31,7 @@ #include <linux/kasan.h> #include <linux/memremap.h> #include <linux/slab.h> +#include <linux/kpkeys.h> struct mempolicy; struct anon_vma;
@@ -2895,7 +2896,19 @@ static inline bool pagetable_is_reserved(struct ptdesc *pt) */ static inline struct ptdesc *pagetable_alloc_noprof(gfp_t gfp, unsigned int order) { - struct page *page = alloc_pages_noprof(gfp | __GFP_COMP, order); + struct page *page; + int ret; + + page = alloc_pages_noprof(gfp | __GFP_COMP, order); + if (!page) + return NULL; + + ret = kpkeys_protect_pgtable_memory((unsigned long)page_address(page), + 1 << order); + if (ret) { + __free_pages(page, order); + return NULL; + } return page_ptdesc(page); }
@@ -2911,8 +2924,11 @@ static inline struct ptdesc *pagetable_alloc_noprof(gfp_t gfp, unsigned int orde static inline void pagetable_free(struct ptdesc *pt) { struct page *page = ptdesc_page(pt); + unsigned int order = compound_order(page); - __free_pages(page, compound_order(page)); + kpkeys_unprotect_pgtable_memory((unsigned long)page_address(page), + 1 << order); + __free_pages(page, order); } #if defined(CONFIG_SPLIT_PTE_PTLOCKS)
--
2.47.0