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Incognito_RCM/source/storage/nx_emmc_bis.c
2020-12-22 15:34:14 +00:00

254 lines
7 KiB
C

/*
* eMMC BIS driver for Nintendo Switch
*
* Copyright (c) 2019 shchmue
* Copyright (c) 2019-2020 CTCaer
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <string.h>
#include <memory_map.h>
#include <sec/se.h>
#include "../storage/nx_emmc.h"
#include <storage/sdmmc.h>
#include <utils/types.h>
#define MAX_CLUSTER_CACHE_ENTRIES 128
#define CLUSTER_LOOKUP_EMPTY_ENTRY 0xFFFFFFFF
#define XTS_CLUSTER_SIZE 0x4000
#define SECTORS_PER_CLUSTER 0x20
typedef struct
{
u32 cluster_num; // index of the cluster in the partition
u32 visit_count; // used for debugging/access analysis
u8 dirty; // has been modified without writeback flag
u8 align[7];
u8 cluster[XTS_CLUSTER_SIZE]; // the cached cluster itself
} cluster_cache_t;
static u8 ks_crypt = 0;
static u8 ks_tweak = 0;
static u32 cluster_cache_end_index = 0;
static emmc_part_t *system_part = NULL;
static u8 *emmc_buffer = (u8 *)NX_BIS_CACHE_ADDR;
static cluster_cache_t *cluster_cache = (cluster_cache_t *)(NX_BIS_CACHE_ADDR + XTS_CLUSTER_SIZE);
static u32 *cluster_lookup = (u32 *)(NX_BIS_CACHE_ADDR + XTS_CLUSTER_SIZE + MAX_CLUSTER_CACHE_ENTRIES * sizeof(cluster_cache_t));
static bool lock_cluster_cache = false;
static void _gf256_mul_x_le(void *block)
{
u32 *pdata = (u32 *)block;
u32 carry = 0;
for (u32 i = 0; i < 4; i++) {
u32 b = pdata[i];
pdata[i] = (b << 1) | carry;
carry = b >> 31;
}
if (carry)
pdata[0x0] ^= 0x87;
}
static int _nx_aes_xts_crypt_sec(u32 tweak_ks, u32 crypt_ks, u32 enc, u8 *tweak, bool regen_tweak, u32 tweak_exp, u32 sec, void *dst, const void *src, u32 sec_size)
{
u32 *pdst = (u32 *)dst;
u32 *psrc = (u32 *)src;
u32 *ptweak = (u32 *)tweak;
if (regen_tweak)
{
for (int i = 0xF; i >= 0; i--)
{
tweak[i] = sec & 0xFF;
sec >>= 8;
}
if (!se_aes_crypt_block_ecb(tweak_ks, 1, tweak, tweak))
return 0;
}
// tweak_exp allows us to use a saved tweak to reduce _gf256_mul_x_le calls.
for (u32 i = 0; i < (tweak_exp << 5); i++)
_gf256_mul_x_le(tweak);
u8 orig_tweak[0x10];
memcpy(orig_tweak, tweak, 0x10);
// We are assuming a 0x10-aligned sector size in this implementation.
for (u32 i = 0; i < (sec_size >> 4); i++)
{
for (u32 j = 0; j < 4; j++)
pdst[j] = psrc[j] ^ ptweak[j];
_gf256_mul_x_le(tweak);
psrc += 4;
pdst += 4;
}
if (!se_aes_crypt_ecb(crypt_ks, enc, dst, sec_size, dst, sec_size))
return 0;
pdst = (u32 *)dst;
ptweak = (u32 *)orig_tweak;
for (u32 i = 0; i < (sec_size >> 4); i++)
{
for (u32 j = 0; j < 4; j++)
pdst[j] = pdst[j] ^ ptweak[j];
_gf256_mul_x_le(orig_tweak);
pdst += 4;
}
return 1;
}
static int nx_emmc_bis_read_block(u32 sector, u32 count, void *buff)
{
if (!system_part)
return 3; // Not ready.
static u32 prev_cluster = -1;
static u32 prev_sector = 0;
static u8 tweak[0x10];
u32 tweak_exp = 0;
bool regen_tweak = true;
u32 cluster = sector / SECTORS_PER_CLUSTER;
u32 aligned_sector = cluster * SECTORS_PER_CLUSTER;
u32 sector_index_in_cluster = sector % SECTORS_PER_CLUSTER;
u32 cluster_lookup_index = cluster_lookup[cluster];
if (cluster_lookup_index != CLUSTER_LOOKUP_EMPTY_ENTRY)
{
memcpy(buff, cluster_cache[cluster_lookup_index].cluster + sector_index_in_cluster * NX_EMMC_BLOCKSIZE, count * NX_EMMC_BLOCKSIZE);
cluster_cache[cluster_lookup_index].visit_count++;
prev_sector = sector + count - 1;
prev_cluster = cluster;
return 0; // Success.
}
// Only cache single-sector reads as these are most likely to be repeated, such as boot block and FAT directory tables.
if (count == 1 &&
!lock_cluster_cache &&
cluster_cache_end_index < MAX_CLUSTER_CACHE_ENTRIES &&
cluster_lookup_index == CLUSTER_LOOKUP_EMPTY_ENTRY)
{
cluster_cache[cluster_cache_end_index].cluster_num = cluster;
cluster_cache[cluster_cache_end_index].visit_count = 1;
cluster_cache[cluster_cache_end_index].dirty = 0;
cluster_lookup[cluster] = cluster_cache_end_index;
// Read and decrypt the whole cluster the sector resides in.
if (!nx_emmc_part_read(&emmc_storage, system_part, aligned_sector, SECTORS_PER_CLUSTER, emmc_buffer))
return 1; // R/W error.
if (!_nx_aes_xts_crypt_sec(ks_tweak, ks_crypt, 0, tweak, true, 0, cluster, emmc_buffer, emmc_buffer, XTS_CLUSTER_SIZE))
return 1; // R/W error.
// Copy to cluster cache.
memcpy(cluster_cache[cluster_cache_end_index].cluster, emmc_buffer, XTS_CLUSTER_SIZE);
memcpy(buff, emmc_buffer + sector_index_in_cluster * NX_EMMC_BLOCKSIZE, NX_EMMC_BLOCKSIZE);
prev_cluster = -1;
prev_sector = 0;
cluster_cache_end_index++;
return 0; // Success.
}
// If not reading from or writing to cache, do a regular read and decrypt.
if (!nx_emmc_part_read(&emmc_storage, system_part, sector, count, buff))
return 1; // R/W error.
if (prev_cluster != cluster) // Sector in different cluster than last read.
{
prev_cluster = cluster;
tweak_exp = sector_index_in_cluster;
}
else if (sector > prev_sector) // Sector in same cluster and past last sector.
{
// Calculates the new tweak using the saved one, reducing expensive _gf256_mul_x_le calls.
tweak_exp = sector - prev_sector - 1;
regen_tweak = false;
}
else // Sector in same cluster and before or same as last sector.
tweak_exp = sector_index_in_cluster;
// Maximum one cluster (1 XTS crypto block 16KB).
if (!_nx_aes_xts_crypt_sec(ks_tweak, ks_crypt, 0, tweak, regen_tweak, tweak_exp, prev_cluster, buff, buff, count * NX_EMMC_BLOCKSIZE))
return 1; // R/W error.
prev_sector = sector + count - 1;
return 0; // Success.
}
int nx_emmc_bis_read(u32 sector, u32 count, void *buff)
{
int res = 1;
u8 *buf = (u8 *)buff;
u32 curr_sct = sector;
while (count)
{
u32 sct_cnt = MIN(count, 0x20);
res = nx_emmc_bis_read_block(curr_sct, sct_cnt, buf);
if (res)
return 1;
count -= sct_cnt;
curr_sct += sct_cnt;
buf += NX_EMMC_BLOCKSIZE * sct_cnt;
}
return res;
}
void nx_emmc_bis_cluster_cache_init() {
// Clear cluster lookup table and reset end index.
memset(cluster_lookup, -1, (system_part->lba_end - system_part->lba_start + 1) / SECTORS_PER_CLUSTER * sizeof(*cluster_lookup));
cluster_cache_end_index = 0;
lock_cluster_cache = false;
}
void nx_emmc_bis_init(emmc_part_t *part)
{
system_part = part;
nx_emmc_bis_cluster_cache_init();
switch (part->index)
{
case 0: // PRODINFO.
case 1: // PRODINFOF.
ks_crypt = 0;
ks_tweak = 1;
break;
case 8: // SAFE.
ks_crypt = 2;
ks_tweak = 3;
break;
case 9: // SYSTEM.
case 10: // USER.
ks_crypt = 4;
ks_tweak = 5;
break;
}
}
// Set cluster cache lock according to arg.
void nx_emmc_bis_cache_lock(bool lock)
{
lock_cluster_cache = lock;
}