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pagemap: do not leak physical addresses to non-privileged userspace

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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 <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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: mancha security <mancha1@zoho.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kirill A. Shutemov 2015-03-09 23:11:12 +02:00 committed by Greg Kroah-Hartman
parent 391f1c610a
commit e11b708502
1 changed files with 10 additions and 0 deletions
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10
fs/proc/task_mmu.c
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@ -1110,9 +1110,19 @@ 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 */