From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937760AbeBUOeT convert rfc822-to-8bit (ORCPT ); Wed, 21 Feb 2018 09:34:19 -0500 Received: from prv-mh.provo.novell.com ([137.65.248.74]:51355 "EHLO prv-mh.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934349AbeBUOeO (ORCPT ); Wed, 21 Feb 2018 09:34:14 -0500 Message-Id: <5A8D917302000078001AA055@prv-mh.provo.novell.com> X-Mailer: Novell GroupWise Internet Agent 18.0.0 Date: Wed, 21 Feb 2018 07:34:11 -0700 From: "Jan Beulich" To: , , Cc: "Boris Ostrovsky" , "Juergen Gross" , Subject: [PATCH v2] x86: consider effective protection attributes in W+X check Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using just the leaf page table entry flags would cause a false warning in case _PAGE_RW is clear or _PAGE_NX is set in a higher level entry. Hand through both the current entry's flags as well as the accumulated effective value (the latter as pgprotval_t instead of pgprot_t, as it's not an actual entry's value). This in particular eliminates the false W+X warning when running under Xen, as commit 2cc42bac1c ("x86-64/Xen: eliminate W+X mappings") has to make the necessary adjustment in L2 rather than L1 (the reason is explained there). I.e. _PAGE_RW is clear there in L1, but _PAGE_NX is set in L2. Signed-off-by: Jan Beulich Reviewed-by: Juergen Gross --- v2: Re-base onto tip tree. Add Xen related paragraph to description. --- arch/x86/mm/dump_pagetables.c | 92 ++++++++++++++++++++++++++---------------- 1 file changed, 57 insertions(+), 35 deletions(-) --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -29,6 +29,7 @@ struct pg_state { int level; pgprot_t current_prot; + pgprotval_t effective_prot; unsigned long start_address; unsigned long current_address; const struct addr_marker *marker; @@ -235,9 +236,9 @@ static unsigned long normalize_addr(unsi * print what we collected so far. */ static void note_page(struct seq_file *m, struct pg_state *st, - pgprot_t new_prot, int level) + pgprot_t new_prot, pgprotval_t new_eff, int level) { - pgprotval_t prot, cur; + pgprotval_t prot, cur, eff; static const char units[] = "BKMGTPE"; /* @@ -247,23 +248,24 @@ static void note_page(struct seq_file *m */ prot = pgprot_val(new_prot); cur = pgprot_val(st->current_prot); + eff = st->effective_prot; if (!st->level) { /* First entry */ st->current_prot = new_prot; + st->effective_prot = new_eff; st->level = level; st->marker = address_markers; st->lines = 0; pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n", st->marker->name); - } else if (prot != cur || level != st->level || + } else if (prot != cur || new_eff != eff || level != st->level || st->current_address >= st->marker[1].start_address) { const char *unit = units; unsigned long delta; int width = sizeof(unsigned long) * 2; - pgprotval_t pr = pgprot_val(st->current_prot); - if (st->check_wx && (pr & _PAGE_RW) && !(pr & _PAGE_NX)) { + if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX)) { WARN_ONCE(1, "x86/mm: Found insecure W+X mapping at address %p/%pS\n", (void *)st->start_address, @@ -317,21 +319,30 @@ static void note_page(struct seq_file *m st->start_address = st->current_address; st->current_prot = new_prot; + st->effective_prot = new_eff; st->level = level; } } -static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, unsigned long P) +static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2) +{ + return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) | + ((prot1 | prot2) & _PAGE_NX); +} + +static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, + pgprotval_t eff_in, unsigned long P) { int i; pte_t *start; - pgprotval_t prot; + pgprotval_t prot, eff; start = (pte_t *)pmd_page_vaddr(addr); for (i = 0; i < PTRS_PER_PTE; i++) { prot = pte_flags(*start); + eff = effective_prot(eff_in, prot); st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT); - note_page(m, st, __pgprot(prot), 5); + note_page(m, st, __pgprot(prot), eff, 5); start++; } } @@ -366,42 +377,45 @@ static inline bool kasan_page_table(stru #if PTRS_PER_PMD > 1 -static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, unsigned long P) +static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, + pgprotval_t eff_in, unsigned long P) { int i; pmd_t *start, *pmd_start; - pgprotval_t prot; + pgprotval_t prot, eff; pmd_start = start = (pmd_t *)pud_page_vaddr(addr); for (i = 0; i < PTRS_PER_PMD; i++) { st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT); if (!pmd_none(*start)) { + prot = pmd_flags(*start); + eff = effective_prot(eff_in, prot); if (pmd_large(*start) || !pmd_present(*start)) { - prot = pmd_flags(*start); - note_page(m, st, __pgprot(prot), 4); + note_page(m, st, __pgprot(prot), eff, 4); } else if (!kasan_page_table(m, st, pmd_start)) { - walk_pte_level(m, st, *start, + walk_pte_level(m, st, *start, eff, P + i * PMD_LEVEL_MULT); } } else - note_page(m, st, __pgprot(0), 4); + note_page(m, st, __pgprot(0), 0, 4); start++; } } #else -#define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p) +#define walk_pmd_level(m,s,a,e,p) walk_pte_level(m,s,__pmd(pud_val(a)),e,p) #define pud_large(a) pmd_large(__pmd(pud_val(a))) #define pud_none(a) pmd_none(__pmd(pud_val(a))) #endif #if PTRS_PER_PUD > 1 -static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr, unsigned long P) +static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr, + pgprotval_t eff_in, unsigned long P) { int i; pud_t *start, *pud_start; - pgprotval_t prot; + pgprotval_t prot, eff; pud_t *prev_pud = NULL; pud_start = start = (pud_t *)p4d_page_vaddr(addr); @@ -409,15 +423,16 @@ static void walk_pud_level(struct seq_fi for (i = 0; i < PTRS_PER_PUD; i++) { st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT); if (!pud_none(*start)) { + prot = pud_flags(*start); + eff = effective_prot(eff_in, prot); if (pud_large(*start) || !pud_present(*start)) { - prot = pud_flags(*start); - note_page(m, st, __pgprot(prot), 3); + note_page(m, st, __pgprot(prot), eff, 3); } else if (!kasan_page_table(m, st, pud_start)) { - walk_pmd_level(m, st, *start, + walk_pmd_level(m, st, *start, eff, P + i * PUD_LEVEL_MULT); } } else - note_page(m, st, __pgprot(0), 3); + note_page(m, st, __pgprot(0), 0, 3); prev_pud = start; start++; @@ -425,34 +440,36 @@ static void walk_pud_level(struct seq_fi } #else -#define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(p4d_val(a)),p) +#define walk_pud_level(m,s,a,e,p) walk_pmd_level(m,s,__pud(p4d_val(a)),e,p) #define p4d_large(a) pud_large(__pud(p4d_val(a))) #define p4d_none(a) pud_none(__pud(p4d_val(a))) #endif -static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr, unsigned long P) +static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr, + pgprotval_t eff_in, unsigned long P) { int i; p4d_t *start, *p4d_start; - pgprotval_t prot; + pgprotval_t prot, eff; if (PTRS_PER_P4D == 1) - return walk_pud_level(m, st, __p4d(pgd_val(addr)), P); + return walk_pud_level(m, st, __p4d(pgd_val(addr)), eff_in, P); p4d_start = start = (p4d_t *)pgd_page_vaddr(addr); for (i = 0; i < PTRS_PER_P4D; i++) { st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT); if (!p4d_none(*start)) { + prot = p4d_flags(*start); + eff = effective_prot(eff_in, prot); if (p4d_large(*start) || !p4d_present(*start)) { - prot = p4d_flags(*start); - note_page(m, st, __pgprot(prot), 2); + note_page(m, st, __pgprot(prot), eff, 2); } else if (!kasan_page_table(m, st, p4d_start)) { - walk_pud_level(m, st, *start, + walk_pud_level(m, st, *start, eff, P + i * P4D_LEVEL_MULT); } } else - note_page(m, st, __pgprot(0), 2); + note_page(m, st, __pgprot(0), 0, 2); start++; } @@ -483,7 +500,7 @@ static void ptdump_walk_pgd_level_core(s #else pgd_t *start = swapper_pg_dir; #endif - pgprotval_t prot; + pgprotval_t prot, eff; int i; struct pg_state st = {}; @@ -499,15 +516,20 @@ static void ptdump_walk_pgd_level_core(s for (i = 0; i < PTRS_PER_PGD; i++) { st.current_address = normalize_addr(i * PGD_LEVEL_MULT); if (!pgd_none(*start) && !is_hypervisor_range(i)) { + prot = pgd_flags(*start); +#ifdef CONFIG_X86_PAE + eff = _PAGE_USER | _PAGE_RW; +#else + eff = prot; +#endif if (pgd_large(*start) || !pgd_present(*start)) { - prot = pgd_flags(*start); - note_page(m, &st, __pgprot(prot), 1); + note_page(m, &st, __pgprot(prot), eff, 1); } else { - walk_p4d_level(m, &st, *start, + walk_p4d_level(m, &st, *start, eff, i * PGD_LEVEL_MULT); } } else - note_page(m, &st, __pgprot(0), 1); + note_page(m, &st, __pgprot(0), 0, 1); cond_resched(); start++; @@ -515,7 +537,7 @@ static void ptdump_walk_pgd_level_core(s /* Flush out the last page */ st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT); - note_page(m, &st, __pgprot(0), 0); + note_page(m, &st, __pgprot(0), 0, 0); if (!checkwx) return; if (st.wx_pages)