Messages in this thread Patch in this message | | | Date | Fri, 15 May 2015 10:06:13 +0200 | From | Willy Tarreau <> | Subject | [ 43/48] pagemap: do not leak physical addresses to non-privileged userspace |
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2.6.32-longterm review patch. If anyone has any objections, please let me know.
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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> (cherry picked from commit 1ffc3cd9a36b504c20ce98fe5eeb5463f389e1ac)
Signed-off-by: Willy Tarreau <w@1wt.eu> --- fs/proc/task_mmu.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 3b7b82a..73db5a6 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -773,9 +773,19 @@ 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 */ -- 1.7.12.2.21.g234cd45.dirty
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