diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0092-Map-the-vsyscall-page-with-_PAGE_USER.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0092-Map-the-vsyscall-page-with-_PAGE_USER.patch | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0092-Map-the-vsyscall-page-with-_PAGE_USER.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0092-Map-the-vsyscall-page-with-_PAGE_USER.patch new file mode 100644 index 00000000..348bade7 --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0092-Map-the-vsyscall-page-with-_PAGE_USER.patch @@ -0,0 +1,151 @@ +From a3834ca12f7d16891da85363f2ce1459a768d216 Mon Sep 17 00:00:00 2001 +From: Borislav Petkov <bp@suse.de> +Date: Thu, 4 Jan 2018 17:42:45 +0100 +Subject: [PATCH 092/103] Map the vsyscall page with _PAGE_USER + +This needs to happen early in kaiser_pagetable_walk(), before the +hierarchy is established so that _PAGE_USER permission can be really +set. + +A proper fix would be to teach kaiser_pagetable_walk() to update those +permissions but the vsyscall page is the only exception here so ... + +Signed-off-by: Borislav Petkov <bp@suse.de> +Acked-by: Hugh Dickins <hughd@google.com> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + arch/x86/entry/vsyscall/vsyscall_64.c | 5 +++++ + arch/x86/include/asm/vsyscall.h | 2 ++ + arch/x86/mm/kaiser.c | 34 ++++++++++++++++++++++++++++++---- + 3 files changed, 37 insertions(+), 4 deletions(-) + +diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c +index 636c4b3..6bb7e92 100644 +--- a/arch/x86/entry/vsyscall/vsyscall_64.c ++++ b/arch/x86/entry/vsyscall/vsyscall_64.c +@@ -66,6 +66,11 @@ static int __init vsyscall_setup(char *str) + } + early_param("vsyscall", vsyscall_setup); + ++bool vsyscall_enabled(void) ++{ ++ return vsyscall_mode != NONE; ++} ++ + static void warn_bad_vsyscall(const char *level, struct pt_regs *regs, + const char *message) + { +diff --git a/arch/x86/include/asm/vsyscall.h b/arch/x86/include/asm/vsyscall.h +index 6ba66ee..4865e10 100644 +--- a/arch/x86/include/asm/vsyscall.h ++++ b/arch/x86/include/asm/vsyscall.h +@@ -12,12 +12,14 @@ extern void map_vsyscall(void); + * Returns true if handled. + */ + extern bool emulate_vsyscall(struct pt_regs *regs, unsigned long address); ++extern bool vsyscall_enabled(void); + #else + static inline void map_vsyscall(void) {} + static inline bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) + { + return false; + } ++static inline bool vsyscall_enabled(void) { return false; } + #endif + + #endif /* _ASM_X86_VSYSCALL_H */ +diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c +index 42a5307..a8ade08 100644 +--- a/arch/x86/mm/kaiser.c ++++ b/arch/x86/mm/kaiser.c +@@ -19,6 +19,7 @@ + #include <asm/pgalloc.h> + #include <asm/desc.h> + #include <asm/cmdline.h> ++#include <asm/vsyscall.h> + + int kaiser_enabled __read_mostly = 1; + EXPORT_SYMBOL(kaiser_enabled); /* for inlined TLB flush functions */ +@@ -110,12 +111,13 @@ static inline unsigned long get_pa_from_mapping(unsigned long vaddr) + * + * Returns a pointer to a PTE on success, or NULL on failure. + */ +-static pte_t *kaiser_pagetable_walk(unsigned long address) ++static pte_t *kaiser_pagetable_walk(unsigned long address, bool user) + { + pmd_t *pmd; + pud_t *pud; + pgd_t *pgd = native_get_shadow_pgd(pgd_offset_k(address)); + gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO); ++ unsigned long prot = _KERNPG_TABLE; + + if (pgd_none(*pgd)) { + WARN_ONCE(1, "All shadow pgds should have been populated"); +@@ -123,6 +125,17 @@ static pte_t *kaiser_pagetable_walk(unsigned long address) + } + BUILD_BUG_ON(pgd_large(*pgd) != 0); + ++ if (user) { ++ /* ++ * The vsyscall page is the only page that will have ++ * _PAGE_USER set. Catch everything else. ++ */ ++ BUG_ON(address != VSYSCALL_ADDR); ++ ++ set_pgd(pgd, __pgd(pgd_val(*pgd) | _PAGE_USER)); ++ prot = _PAGE_TABLE; ++ } ++ + pud = pud_offset(pgd, address); + /* The shadow page tables do not use large mappings: */ + if (pud_large(*pud)) { +@@ -135,7 +148,7 @@ static pte_t *kaiser_pagetable_walk(unsigned long address) + return NULL; + spin_lock(&shadow_table_allocation_lock); + if (pud_none(*pud)) { +- set_pud(pud, __pud(_KERNPG_TABLE | __pa(new_pmd_page))); ++ set_pud(pud, __pud(prot | __pa(new_pmd_page))); + __inc_zone_page_state(virt_to_page((void *) + new_pmd_page), NR_KAISERTABLE); + } else +@@ -155,7 +168,7 @@ static pte_t *kaiser_pagetable_walk(unsigned long address) + return NULL; + spin_lock(&shadow_table_allocation_lock); + if (pmd_none(*pmd)) { +- set_pmd(pmd, __pmd(_KERNPG_TABLE | __pa(new_pte_page))); ++ set_pmd(pmd, __pmd(prot | __pa(new_pte_page))); + __inc_zone_page_state(virt_to_page((void *) + new_pte_page), NR_KAISERTABLE); + } else +@@ -193,7 +206,7 @@ static int kaiser_add_user_map(const void *__start_addr, unsigned long size, + ret = -EIO; + break; + } +- pte = kaiser_pagetable_walk(address); ++ pte = kaiser_pagetable_walk(address, flags & _PAGE_USER); + if (!pte) { + ret = -ENOMEM; + break; +@@ -320,6 +333,19 @@ void __init kaiser_init(void) + + kaiser_init_all_pgds(); + ++ /* ++ * Note that this sets _PAGE_USER and it needs to happen when the ++ * pagetable hierarchy gets created, i.e., early. Otherwise ++ * kaiser_pagetable_walk() will encounter initialized PTEs in the ++ * hierarchy and not set the proper permissions, leading to the ++ * pagefaults with page-protection violations when trying to read the ++ * vsyscall page. For example. ++ */ ++ if (vsyscall_enabled()) ++ kaiser_add_user_map_early((void *)VSYSCALL_ADDR, ++ PAGE_SIZE, ++ __PAGE_KERNEL_VSYSCALL); ++ + for_each_possible_cpu(cpu) { + void *percpu_vaddr = __per_cpu_user_mapped_start + + per_cpu_offset(cpu); +-- +2.7.4 + |