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Commit 2d62d5ff authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Christian Bejram
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BACKPORT: pagemap: do not leak physical addresses to non-privileged userspace

(cherry pick from commit ab676b7d)

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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: default avatarAndy 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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarMark Salyzyn <salyzyn@google.com>
Bug: 25739721
Change-Id: I5582c993dbeb0b7287e6d41b57e494d123d33083
Signed-off-by: default avatarChristian Bejram <cbejram@google.com>
parent cdf641bf
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......@@ -1181,9 +1181,18 @@ 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 */
......
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