Reviewed-by: Mark Williamson <[email protected]>
On Tue, Jul 21, 2015 at 9:39 AM, Konstantin Khlebnikov <[email protected]> wrote: > On Tue, Jul 21, 2015 at 11:11 AM, Naoya Horiguchi > <[email protected]> wrote: >> On Tue, Jul 14, 2015 at 06:37:47PM +0300, Konstantin Khlebnikov wrote: >>> This patch makes pagemap readable for normal users and hides physical >>> addresses from them. For some use-cases PFN isn't required at all. >>> >>> Signed-off-by: Konstantin Khlebnikov <[email protected]> >>> Fixes: ab676b7d6fbf ("pagemap: do not leak physical addresses to >>> non-privileged userspace") >>> Link: >>> http://lkml.kernel.org/r/[email protected] >>> --- >>> fs/proc/task_mmu.c | 25 ++++++++++++++----------- >>> 1 file changed, 14 insertions(+), 11 deletions(-) >>> >>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c >>> index 040721fa405a..3a5d338ea219 100644 >>> --- a/fs/proc/task_mmu.c >>> +++ b/fs/proc/task_mmu.c >>> @@ -937,6 +937,7 @@ typedef struct { >>> struct pagemapread { >>> int pos, len; /* units: PM_ENTRY_BYTES, not bytes */ >>> pagemap_entry_t *buffer; >>> + bool show_pfn; >>> }; >>> >>> #define PAGEMAP_WALK_SIZE (PMD_SIZE) >>> @@ -1013,7 +1014,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct >>> pagemapread *pm, >>> struct page *page = NULL; >>> >>> if (pte_present(pte)) { >>> - frame = pte_pfn(pte); >>> + if (pm->show_pfn) >>> + frame = pte_pfn(pte); >>> flags |= PM_PRESENT; >>> page = vm_normal_page(vma, addr, pte); >>> if (pte_soft_dirty(pte)) >> >> Don't you need the same if (pm->show_pfn) check in is_swap_pte path, too? >> (although I don't think that it can be exploited by row hammer attack ...) > > Yeah, but I see no reason for that. > Probably except swap on ramdrive, but this too weird =) > >> >> Thanks, >> Naoya Horiguchi >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to [email protected]. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: <a hrefmailto:"[email protected]";> [email protected] </a> -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
