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x86/xen: allow userspace access during hypercalls

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Userspace application can do a hypercall through /dev/xen/privcmd, and
some for some hypercalls argument is a pointers to user-provided
structure. When SMAP is supported and enabled, hypervisor can't access.
So, lets allow it.

The same applies to HYPERVISOR_dm_op, where additionally privcmd driver
carefully verify buffer addresses.

Cc: stable@vger.kernel.org
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Marek Marczykowski-Górecki
2017-06-26 14:49:46 +02:00
committed by Juergen Gross
parent bf1b9ddf18
commit c54590cac5
1 changed files with 8 additions and 1 deletions
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9
arch/x86/include/asm/xen/hypercall.h
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@@ -43,6 +43,7 @@
#include <asm/page.h> #include <asm/page.h>
#include <asm/pgtable.h> #include <asm/pgtable.h>
#include <asm/smap.h>
#include <xen/interface/xen.h> #include <xen/interface/xen.h>
#include <xen/interface/sched.h> #include <xen/interface/sched.h>
@@ -216,10 +217,12 @@ privcmd_call(unsigned call,
__HYPERCALL_DECLS; __HYPERCALL_DECLS;
__HYPERCALL_5ARG(a1, a2, a3, a4, a5); __HYPERCALL_5ARG(a1, a2, a3, a4, a5);
stac();
asm volatile("call *%[call]" asm volatile("call *%[call]"
: __HYPERCALL_5PARAM : __HYPERCALL_5PARAM
: [call] "a" (&hypercall_page[call]) : [call] "a" (&hypercall_page[call])
: __HYPERCALL_CLOBBER5); : __HYPERCALL_CLOBBER5);
clac();
return (long)__res; return (long)__res;
} }
@@ -478,7 +481,11 @@ static inline int
HYPERVISOR_dm_op( HYPERVISOR_dm_op(
domid_t dom, unsigned int nr_bufs, struct xen_dm_op_buf *bufs) domid_t dom, unsigned int nr_bufs, struct xen_dm_op_buf *bufs)
{ {
return _hypercall3(int, dm_op, dom, nr_bufs, bufs); int ret;
stac();
ret = _hypercall3(int, dm_op, dom, nr_bufs, bufs);
clac();
return ret;
} }
static inline void static inline void