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 <kirill.shutemov@linux.intel.com>
Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Seaborn <mseaborn@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 25739721
Change-Id: I5582c993dbeb0b7287e6d41b57e494d123d33083
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e5bc1c7..65f0cb8 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1187,9 +1187,18 @@
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 */
