From b152bb944d40c369236e0d642f8296fdbacabfa2 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 13 Jan 2016 16:28:49 -0500 Subject: BACKPORT: pagemap: do not leak physical addresses to non-privileged userspace (cherry pick from commit ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce) As pointed by recent post[1] on exploiting DRAM physical imperfection, /proc/PID/pagemap exposes sensitive information which can be used to do attacks. This disallows anybody without CAP_SYS_ADMIN to read the pagemap. [1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html [ Eventually we might want to do anything more finegrained, but for now this is the simple model. - Linus ] Signed-off-by: Kirill A. Shutemov Acked-by: Konstantin Khlebnikov Acked-by: Andy Lutomirski Cc: Pavel Emelyanov Cc: Andrew Morton Cc: Mark Seaborn Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Mark Salyzyn Bug: 26038811 Change-Id: Icd68075a32ef6c9be1ae00ae9cf5a68bbe7f4e4f --- fs/proc/task_mmu.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'fs') diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 55a1f49..00e7ac4 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -862,9 +862,18 @@ out: return ret; } +static int pagemap_open(struct inode *inode, struct file *file) +{ + /* do not disclose physical addresses: attack vector */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + return 0; +} + const struct file_operations proc_pagemap_operations = { .llseek = mem_lseek, /* borrow this */ .read = pagemap_read, + .open = pagemap_open, }; #endif /* CONFIG_PROC_PAGE_MONITOR */ -- cgit v1.1