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-rw-r--r--arch/s390/boot/kaslr.c198
1 files changed, 198 insertions, 0 deletions
diff --git a/arch/s390/boot/kaslr.c b/arch/s390/boot/kaslr.c
new file mode 100644
index 0000000000..90602101e2
--- /dev/null
+++ b/arch/s390/boot/kaslr.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright IBM Corp. 2019
+ */
+#include <linux/pgtable.h>
+#include <asm/physmem_info.h>
+#include <asm/cpacf.h>
+#include <asm/timex.h>
+#include <asm/sclp.h>
+#include <asm/kasan.h>
+#include "decompressor.h"
+#include "boot.h"
+
+#define PRNG_MODE_TDES 1
+#define PRNG_MODE_SHA512 2
+#define PRNG_MODE_TRNG 3
+
+struct prno_parm {
+ u32 res;
+ u32 reseed_counter;
+ u64 stream_bytes;
+ u8 V[112];
+ u8 C[112];
+};
+
+struct prng_parm {
+ u8 parm_block[32];
+ u32 reseed_counter;
+ u64 byte_counter;
+};
+
+static int check_prng(void)
+{
+ if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG)) {
+ sclp_early_printk("KASLR disabled: CPU has no PRNG\n");
+ return 0;
+ }
+ if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
+ return PRNG_MODE_TRNG;
+ if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN))
+ return PRNG_MODE_SHA512;
+ else
+ return PRNG_MODE_TDES;
+}
+
+static int get_random(unsigned long limit, unsigned long *value)
+{
+ struct prng_parm prng = {
+ /* initial parameter block for tdes mode, copied from libica */
+ .parm_block = {
+ 0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
+ 0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
+ 0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
+ 0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0
+ },
+ };
+ unsigned long seed, random;
+ struct prno_parm prno;
+ __u64 entropy[4];
+ int mode, i;
+
+ mode = check_prng();
+ seed = get_tod_clock_fast();
+ switch (mode) {
+ case PRNG_MODE_TRNG:
+ cpacf_trng(NULL, 0, (u8 *) &random, sizeof(random));
+ break;
+ case PRNG_MODE_SHA512:
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED, &prno, NULL, 0,
+ (u8 *) &seed, sizeof(seed));
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN, &prno, (u8 *) &random,
+ sizeof(random), NULL, 0);
+ break;
+ case PRNG_MODE_TDES:
+ /* add entropy */
+ *(unsigned long *) prng.parm_block ^= seed;
+ for (i = 0; i < 16; i++) {
+ cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block,
+ (u8 *) entropy, (u8 *) entropy,
+ sizeof(entropy));
+ memcpy(prng.parm_block, entropy, sizeof(entropy));
+ }
+ random = seed;
+ cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block, (u8 *) &random,
+ (u8 *) &random, sizeof(random));
+ break;
+ default:
+ return -1;
+ }
+ *value = random % limit;
+ return 0;
+}
+
+static void sort_reserved_ranges(struct reserved_range *res, unsigned long size)
+{
+ struct reserved_range tmp;
+ int i, j;
+
+ for (i = 1; i < size; i++) {
+ tmp = res[i];
+ for (j = i - 1; j >= 0 && res[j].start > tmp.start; j--)
+ res[j + 1] = res[j];
+ res[j + 1] = tmp;
+ }
+}
+
+static unsigned long iterate_valid_positions(unsigned long size, unsigned long align,
+ unsigned long _min, unsigned long _max,
+ struct reserved_range *res, size_t res_count,
+ bool pos_count, unsigned long find_pos)
+{
+ unsigned long start, end, tmp_end, range_pos, pos = 0;
+ struct reserved_range *res_end = res + res_count;
+ struct reserved_range *skip_res;
+ int i;
+
+ align = max(align, 8UL);
+ _min = round_up(_min, align);
+ for_each_physmem_usable_range(i, &start, &end) {
+ if (_min >= end)
+ continue;
+ start = round_up(start, align);
+ if (start >= _max)
+ break;
+ start = max(_min, start);
+ end = min(_max, end);
+
+ while (start + size <= end) {
+ /* skip reserved ranges below the start */
+ while (res && res->end <= start) {
+ res++;
+ if (res >= res_end)
+ res = NULL;
+ }
+ skip_res = NULL;
+ tmp_end = end;
+ /* has intersecting reserved range */
+ if (res && res->start < end) {
+ skip_res = res;
+ tmp_end = res->start;
+ }
+ if (start + size <= tmp_end) {
+ range_pos = (tmp_end - start - size) / align + 1;
+ if (pos_count) {
+ pos += range_pos;
+ } else {
+ if (range_pos >= find_pos)
+ return start + (find_pos - 1) * align;
+ find_pos -= range_pos;
+ }
+ }
+ if (!skip_res)
+ break;
+ start = round_up(skip_res->end, align);
+ }
+ }
+
+ return pos_count ? pos : 0;
+}
+
+/*
+ * Two types of decompressor memory allocations/reserves are considered
+ * differently.
+ *
+ * "Static" or "single" allocations are done via physmem_alloc_range() and
+ * physmem_reserve(), and they are listed in physmem_info.reserved[]. Each
+ * type of "static" allocation can only have one allocation per type and
+ * cannot have chains.
+ *
+ * On the other hand, "dynamic" or "repetitive" allocations are done via
+ * physmem_alloc_top_down(). These allocations are tightly packed together
+ * top down from the end of online memory. physmem_alloc_pos represents
+ * current position where those allocations start.
+ *
+ * Functions randomize_within_range() and iterate_valid_positions()
+ * only consider "dynamic" allocations by never looking above
+ * physmem_alloc_pos. "Static" allocations, however, are explicitly
+ * considered by checking the "res" (reserves) array. The first
+ * reserved_range of a "dynamic" allocation may also be checked along the
+ * way, but it will always be above the maximum value anyway.
+ */
+unsigned long randomize_within_range(unsigned long size, unsigned long align,
+ unsigned long min, unsigned long max)
+{
+ struct reserved_range res[RR_MAX];
+ unsigned long max_pos, pos;
+
+ memcpy(res, physmem_info.reserved, sizeof(res));
+ sort_reserved_ranges(res, ARRAY_SIZE(res));
+ max = min(max, get_physmem_alloc_pos());
+
+ max_pos = iterate_valid_positions(size, align, min, max, res, ARRAY_SIZE(res), true, 0);
+ if (!max_pos)
+ return 0;
+ if (get_random(max_pos, &pos))
+ return 0;
+ return iterate_valid_positions(size, align, min, max, res, ARRAY_SIZE(res), false, pos + 1);
+}