From 863055dedd44a51c1ec8681df36903d7b3a5d650 Mon Sep 17 00:00:00 2001 From: Huang Ying Date: Thu, 7 Jun 2018 17:07:39 -0700 Subject: [PATCH] mm: /proc/pid/pagemap: hide swap entries from unprivileged users BugLink: http://bugs.launchpad.net/bugs/1815234 [ Upstream commit ab6ecf247a9321e3180e021a6a60164dee53ab2e ] In commit ab676b7d6fbf ("pagemap: do not leak physical addresses to non-privileged userspace"), the /proc/PID/pagemap is restricted to be readable only by CAP_SYS_ADMIN to address some security issue. In commit 1c90308e7a77 ("pagemap: hide physical addresses from non-privileged users"), the restriction is relieved to make /proc/PID/pagemap readable, but hide the physical addresses for non-privileged users. But the swap entries are readable for non-privileged users too. This has some security issues. For example, for page under migrating, the swap entry has physical address information. So, in this patch, the swap entries are hided for non-privileged users too. Link: http://lkml.kernel.org/r/20180508012745.7238-1-ying.huang@intel.com Fixes: 1c90308e7a77 ("pagemap: hide physical addresses from non-privileged users") Signed-off-by: "Huang, Ying" Suggested-by: Kirill A. Shutemov Reviewed-by: Naoya Horiguchi Reviewed-by: Konstantin Khlebnikov Acked-by: Michal Hocko Cc: Konstantin Khlebnikov Cc: Andrei Vagin Cc: Jerome Glisse Cc: Daniel Colascione Cc: Zi Yan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman Signed-off-by: Kamal Mostafa Signed-off-by: Stefan Bader --- fs/proc/task_mmu.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 0a2af2c4af2a..06a302165d85 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1275,8 +1275,9 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm, if (pte_swp_soft_dirty(pte)) flags |= PM_SOFT_DIRTY; entry = pte_to_swp_entry(pte); - frame = swp_type(entry) | - (swp_offset(entry) << MAX_SWAPFILES_SHIFT); + if (pm->show_pfn) + frame = swp_type(entry) | + (swp_offset(entry) << MAX_SWAPFILES_SHIFT); flags |= PM_SWAP; if (is_migration_entry(entry)) page = migration_entry_to_page(entry); @@ -1327,11 +1328,14 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end, #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION else if (is_swap_pmd(pmd)) { swp_entry_t entry = pmd_to_swp_entry(pmd); - unsigned long offset = swp_offset(entry); + unsigned long offset; - offset += (addr & ~PMD_MASK) >> PAGE_SHIFT; - frame = swp_type(entry) | - (offset << MAX_SWAPFILES_SHIFT); + if (pm->show_pfn) { + offset = swp_offset(entry) + + ((addr & ~PMD_MASK) >> PAGE_SHIFT); + frame = swp_type(entry) | + (offset << MAX_SWAPFILES_SHIFT); + } flags |= PM_SWAP; if (pmd_swp_soft_dirty(pmd)) flags |= PM_SOFT_DIRTY; @@ -1349,10 +1353,12 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end, err = add_to_pagemap(addr, &pme, pm); if (err) break; - if (pm->show_pfn && (flags & PM_PRESENT)) - frame++; - else if (flags & PM_SWAP) - frame += (1 << MAX_SWAPFILES_SHIFT); + if (pm->show_pfn) { + if (flags & PM_PRESENT) + frame++; + else if (flags & PM_SWAP) + frame += (1 << MAX_SWAPFILES_SHIFT); + } } spin_unlock(ptl); return err; -- 2.39.5