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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] memory: split and tighten maximum order permitted in memops
commit 4a578b316eb98975374d88f28904acf13dbcfac2
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Dec 8 14:00:33 2015 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Dec 8 14:00:33 2015 +0100
memory: split and tighten maximum order permitted in memops
Introduce and enforce separate limits for ordinary DomU, DomU with
pass-through device(s), control domain, and hardware domain.
The DomU defaults were determined based on what so far was allowed by
multipage_allocation_permitted().
The x86 hwdom default was chosen based on linux-2.6.18-xen.hg c/s
1102:82782f1361a9 indicating 2Mb is not enough, plus some slack.
The ARM hwdom default was chosen to allow 2Mb (order-9) mappings, plus
a little bit of slack.
This is CVE-2015-8338 / XSA-158.
Reported-by: Julien Grall <julien.grall@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
docs/misc/xen-command-line.markdown | 11 +++++
xen/common/memory.c | 72 ++++++++++++++++++++++++++--------
xen/include/asm-arm/config.h | 4 ++
xen/include/asm-arm/iocap.h | 4 --
xen/include/asm-x86/config.h | 5 ++-
xen/include/asm-x86/iocap.h | 5 --
6 files changed, 74 insertions(+), 27 deletions(-)
diff --git a/docs/misc/xen-command-line.markdown
b/docs/misc/xen-command-line.markdown
index 47d148a..3a10432 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1032,6 +1032,17 @@ with **crashinfo_maxaddr**.
Specify the threshold below which Xen will inform dom0 that the quantity of
free memory is getting low. Specifying `0` will disable this notification.
+### memop-max-order
+> `= [<domU>][,[<ctldom>][,[<hwdom>][,<ptdom>]]]`
+
+> x86 default: `9,18,12,12`
+> ARM default: `9,18,10,10`
+
+Change the maximum order permitted for allocation (or allocation-like)
+requests issued by the various kinds of domains (in this order:
+ordinary DomU, control domain, hardware domain, and - when supported
+by the platform - DomU with pass-through device assigned).
+
### max\_cstate
> `= <integer>`
diff --git a/xen/common/memory.c b/xen/common/memory.c
index a3bffb7..e00a0b2 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -43,6 +43,50 @@ struct memop_args {
int preempted; /* Was the hypercall preempted? */
};
+#ifndef CONFIG_CTLDOM_MAX_ORDER
+#define CONFIG_CTLDOM_MAX_ORDER CONFIG_PAGEALLOC_MAX_ORDER
+#endif
+#ifndef CONFIG_PTDOM_MAX_ORDER
+#define CONFIG_PTDOM_MAX_ORDER CONFIG_HWDOM_MAX_ORDER
+#endif
+
+static unsigned int __read_mostly domu_max_order = CONFIG_DOMU_MAX_ORDER;
+static unsigned int __read_mostly ctldom_max_order = CONFIG_CTLDOM_MAX_ORDER;
+static unsigned int __read_mostly hwdom_max_order = CONFIG_HWDOM_MAX_ORDER;
+#ifdef HAS_PASSTHROUGH
+static unsigned int __read_mostly ptdom_max_order = CONFIG_PTDOM_MAX_ORDER;
+#else
+# define ptdom_max_order domu_max_order
+#endif
+static void __init parse_max_order(const char *s)
+{
+ if ( *s != ',' )
+ domu_max_order = simple_strtoul(s, &s, 0);
+ if ( *s == ',' && *++s != ',' )
+ ctldom_max_order = simple_strtoul(s, &s, 0);
+ if ( *s == ',' && *++s != ',' )
+ hwdom_max_order = simple_strtoul(s, &s, 0);
+#ifdef HAS_PASSTHROUGH
+ if ( *s == ',' && *++s != ',' )
+ ptdom_max_order = simple_strtoul(s, &s, 0);
+#endif
+}
+custom_param("memop-max-order", parse_max_order);
+
+static unsigned int max_order(const struct domain *d)
+{
+ unsigned int order = cache_flush_permitted(d) ? domu_max_order
+ : ptdom_max_order;
+
+ if ( is_control_domain(d) && order < ctldom_max_order )
+ order = ctldom_max_order;
+
+ if ( is_hardware_domain(d) && order < hwdom_max_order )
+ order = hwdom_max_order;
+
+ return min(order, MAX_ORDER + 0U);
+}
+
static void increase_reservation(struct memop_args *a)
{
struct page_info *page;
@@ -55,7 +99,7 @@ static void increase_reservation(struct memop_args *a)
a->nr_extents-1) )
return;
- if ( !multipage_allocation_permitted(current->domain, a->extent_order) )
+ if ( a->extent_order > max_order(current->domain) )
return;
for ( i = a->nr_done; i < a->nr_extents; i++ )
@@ -100,8 +144,8 @@ static void populate_physmap(struct memop_args *a)
a->nr_extents-1) )
return;
- if ( a->memflags & MEMF_populate_on_demand ? a->extent_order > MAX_ORDER :
- !multipage_allocation_permitted(current->domain, a->extent_order) )
+ if ( a->extent_order > (a->memflags & MEMF_populate_on_demand ? MAX_ORDER :
+ max_order(current->domain)) )
return;
for ( i = a->nr_done; i < a->nr_extents; i++ )
@@ -285,7 +329,7 @@ static void decrease_reservation(struct memop_args *a)
if ( !guest_handle_subrange_okay(a->extent_list, a->nr_done,
a->nr_extents-1) ||
- a->extent_order > MAX_ORDER )
+ a->extent_order > max_order(current->domain) )
return;
for ( i = a->nr_done; i < a->nr_extents; i++ )
@@ -343,13 +387,17 @@ static long
memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
if ( copy_from_guest(&exch, arg, 1) )
return -EFAULT;
+ if ( max(exch.in.extent_order, exch.out.extent_order) >
+ max_order(current->domain) )
+ {
+ rc = -EPERM;
+ goto fail_early;
+ }
+
/* Various sanity checks. */
if ( (exch.nr_exchanged > exch.in.nr_extents) ||
/* Input and output domain identifiers match? */
(exch.in.domid != exch.out.domid) ||
- /* Extent orders are sensible? */
- (exch.in.extent_order > MAX_ORDER) ||
- (exch.out.extent_order > MAX_ORDER) ||
/* Sizes of input and output lists do not overflow a long? */
((~0UL >> exch.in.extent_order) < exch.in.nr_extents) ||
((~0UL >> exch.out.extent_order) < exch.out.nr_extents) ||
@@ -368,16 +416,6 @@ static long
memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
goto fail_early;
}
- /* Only privileged guests can allocate multi-page contiguous extents. */
- if ( !multipage_allocation_permitted(current->domain,
- exch.in.extent_order) ||
- !multipage_allocation_permitted(current->domain,
- exch.out.extent_order) )
- {
- rc = -EPERM;
- goto fail_early;
- }
-
if ( exch.in.extent_order <= exch.out.extent_order )
{
in_chunk_order = exch.out.extent_order - exch.in.extent_order;
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index 817c216..1520b41 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -39,6 +39,10 @@
#define CONFIG_IRQ_HAS_MULTIPLE_ACTION 1
+#define CONFIG_PAGEALLOC_MAX_ORDER 18
+#define CONFIG_DOMU_MAX_ORDER 9
+#define CONFIG_HWDOM_MAX_ORDER 10
+
#define OPT_CONSOLE_STR "dtuart"
#ifdef MAX_PHYS_CPUS
diff --git a/xen/include/asm-arm/iocap.h b/xen/include/asm-arm/iocap.h
index 22cfa41..276fefb 100644
--- a/xen/include/asm-arm/iocap.h
+++ b/xen/include/asm-arm/iocap.h
@@ -4,10 +4,6 @@
#define cache_flush_permitted(d) \
(!rangeset_is_empty((d)->iomem_caps))
-#define multipage_allocation_permitted(d, order) \
- (((order) <= 9) || /* allow 2MB superpages */ \
- !rangeset_is_empty((d)->iomem_caps))
-
#endif
/*
diff --git a/xen/include/asm-x86/config.h b/xen/include/asm-x86/config.h
index 416a5c2..f25d92e 100644
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -28,9 +28,12 @@
#define CONFIG_NUMA 1
#define CONFIG_DISCONTIGMEM 1
#define CONFIG_NUMA_EMU 1
-#define CONFIG_PAGEALLOC_MAX_ORDER (2 * PAGETABLE_ORDER)
#define CONFIG_DOMAIN_PAGE 1
+#define CONFIG_PAGEALLOC_MAX_ORDER (2 * PAGETABLE_ORDER)
+#define CONFIG_DOMU_MAX_ORDER PAGETABLE_ORDER
+#define CONFIG_HWDOM_MAX_ORDER 12
+
/* Intel P4 currently has largest cache line (L2 line size is 128 bytes). */
#define CONFIG_X86_L1_CACHE_SHIFT 7
diff --git a/xen/include/asm-x86/iocap.h b/xen/include/asm-x86/iocap.h
index 591ae17..eee4722 100644
--- a/xen/include/asm-x86/iocap.h
+++ b/xen/include/asm-x86/iocap.h
@@ -18,9 +18,4 @@
(!rangeset_is_empty((d)->iomem_caps) || \
!rangeset_is_empty((d)->arch.ioport_caps))
-#define multipage_allocation_permitted(d, order) \
- (((order) <= 9) || /* allow 2MB superpages */ \
- !rangeset_is_empty((d)->iomem_caps) || \
- !rangeset_is_empty((d)->arch.ioport_caps))
-
#endif /* __X86_IOCAP_H__ */
--
generated by git-patchbot for /home/xen/git/xen.git#master
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