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    Subject[PATCH 3.2 135/221] pagemap: do not leak physical addresses to non-privileged userspace
    3.2.69-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

    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>
    [mancha security: Backported to 3.10]
    Signed-off-by: mancha security <mancha1@zoho.com>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    fs/proc/task_mmu.c | 10 ++++++++++
    1 file changed, 10 insertions(+)

    --- 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 */



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