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Date: Thu, 14 Apr 2016 15:29:08 -0700
From: Kees Cook <keescook@...omium.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: Kees Cook <keescook@...omium.org>,
Baoquan He <bhe@...hat.com>,
Yinghai Lu <yinghai@...nel.org>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Matt Redfearn <matt.redfearn@...tec.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Vivek Goyal <vgoyal@...hat.com>,
Andy Lutomirski <luto@...nel.org>,
lasse.collin@...aani.org,
Andrew Morton <akpm@...ux-foundation.org>,
Dave Young <dyoung@...hat.com>,
kernel-hardening@...ts.openwall.com,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v5 15/21] x86, KASLR: Add slot_area support functions
From: Baoquan He <bhe@...hat.com>
The function store_slot_info() is used to calculate the slot info of the
passed-in memory region and stores it into slot_areas[] after adjusting
for alignment and size requirements.
The function mem_min_overlap() is used to iterate over all mem_avoid
regions to find the earliest mem_avoid address that conflicts with the
given memory region. (For example, with the region [1024M, 2048M), if
there is a mem_avoid of [1536M, 1664M), this returns 1536M.) This can
be used to split memory regions when building the slot_area array.
Signed-off-by: Baoquan He <bhe@...hat.com>
[kees: rewrote changelog]
Signed-off-by: Kees Cook <keescook@...omium.org>
---
arch/x86/boot/compressed/aslr.c | 51 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index abe618d489ea..b06618000732 100644
--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -257,6 +257,40 @@ static bool mem_avoid_overlap(struct mem_vector *img)
return false;
}
+static unsigned long
+mem_min_overlap(struct mem_vector *img, struct mem_vector *out)
+{
+ int i;
+ struct setup_data *ptr;
+ unsigned long min = img->start + img->size;
+
+ for (i = 0; i < MEM_AVOID_MAX; i++) {
+ if (mem_overlaps(img, &mem_avoid[i]) &&
+ (mem_avoid[i].start < min)) {
+ *out = mem_avoid[i];
+ min = mem_avoid[i].start;
+ }
+ }
+
+ /* Check all entries in the setup_data linked list. */
+ ptr = (struct setup_data *)(unsigned long)real_mode->hdr.setup_data;
+ while (ptr) {
+ struct mem_vector avoid;
+
+ avoid.start = (unsigned long)ptr;
+ avoid.size = sizeof(*ptr) + ptr->len;
+
+ if (mem_overlaps(img, &avoid) && (avoid.start < min)) {
+ *out = avoid;
+ min = avoid.start;
+ }
+
+ ptr = (struct setup_data *)(unsigned long)ptr->next;
+ }
+
+ return min;
+}
+
static unsigned long slots[KERNEL_IMAGE_SIZE / CONFIG_PHYSICAL_ALIGN];
struct slot_area {
@@ -272,6 +306,23 @@ static unsigned long slot_max;
static unsigned long slot_area_index;
+static void store_slot_info(struct mem_vector *region, unsigned long image_size)
+{
+ struct slot_area slot_area;
+
+ slot_area.addr = region->start;
+ if (image_size <= CONFIG_PHYSICAL_ALIGN)
+ slot_area.num = region->size / CONFIG_PHYSICAL_ALIGN;
+ else
+ slot_area.num = (region->size - image_size) /
+ CONFIG_PHYSICAL_ALIGN + 1;
+
+ if (slot_area.num > 0) {
+ slot_areas[slot_area_index++] = slot_area;
+ slot_max += slot_area.num;
+ }
+}
+
static void slots_append(unsigned long addr)
{
/* Overflowing the slots list should be impossible. */
--
2.6.3
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