From 1ffc3cd9a36b504c20ce98fe5eeb5463f389e1ac Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Mon, 9 Mar 2015 23:11:12 +0200 Subject: pagemap: do not leak physical addresses to non-privileged userspace commit ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce upstream. 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 Signed-off-by: Linus Torvalds [mancha security: Backported to 3.10] Signed-off-by: mancha security Signed-off-by: Ben Hutchings --- fs/proc/task_mmu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'fs/proc/task_mmu.c') diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index ef1740d..d1bd6a9 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -864,9 +864,19 @@ out: return ret; } +static int pagemap_open(struct inode *inode, struct file *file) +{ + /* do not disclose physical addresses to unprivileged + userspace (closes a rowhammer 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