Introduce samsungtools to decrypt samsung firmware

Samsung provides many firmware upgrade in the format of a .dat
file, at least for nearly all YP's (checked for Q2, R0, T10, Z5).
This is a simple cyclic xor which a fixed key, a md5 sum and a
header specifying the model/version/region.

Change-Id: Ib0461a74196383189fd2d8162da444a85a229c60

4 files changed, 353 insertions, 0 deletions

diff --git a/utils/samsungtools/Makefile b/utils/samsungtools/Makefile
new file mode 100644
index 0000000000..97af8bb873
--- /dev/null
+++ b/utils/samsungtools/Makefile
@@ -0,0 +1,17 @@
+DEFINES=
+CC=gcc
+LD=gcc
+CFLAGS=-g -std=c99 -W -Wall $(DEFINES) `pkg-config --cflags openssl`
+LDFLAGS=`pkg-config --libs openssl`
+BINS=fwdecrypt
+
+all: $(BINS)
+
+%.o: %.c
+        $(CC) $(CFLAGS) -c -o $@ $<
+
+fwdecrypt: fwdecrypt.o samsung.o
+        $(LD) -o $@ $^ $(LDFLAGS)
+
+clean:
+        rm -fr *.o $(BINS)
diff --git a/utils/samsungtools/fwdecrypt.c b/utils/samsungtools/fwdecrypt.c
new file mode 100644
index 0000000000..67dfb315c2
--- /dev/null
+++ b/utils/samsungtools/fwdecrypt.c
@@ -0,0 +1,131 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2012 Amaury Pouly
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "samsung.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <getopt.h>
+
+static bool g_debug = false;
+static char *g_out_prefix = NULL;
+
+static void usage(void)
+{
+    printf("Usage: fwdecrypt [options] firmware\n");
+    printf("Options:\n");
+    printf("  -o <prefix>\tSet output file\n");
+    printf("  -f/--force\tForce to continue on errors\n");
+    printf("  -?/--help\tDisplay this message\n");
+    printf("  -d/--debug\tDisplay debug messages\n");
+    exit(1);
+}
+
+static int s_read(void *user, int offset, void *buf, int size)
+{
+    FILE *f = user;
+    if(fseek(f, offset, SEEK_SET) != 0)
+        return 0;
+    return fread(buf, 1, size, f);
+}
+
+static void s_printf(void *user, bool error, const char *fmt, ...)
+{
+    if(!g_debug && !error)
+        return;
+    (void) user;
+    va_list args;
+    va_start(args, fmt);
+    vprintf(fmt, args);
+    va_end(args);
+}
+
+int main(int argc, char **argv)
+{
+    if(argc <= 1)
+        usage();
+
+    while(1)
+    {
+        static struct option long_options[] =
+        {
+            {"help", no_argument, 0, '?'},
+            {"debug", no_argument, 0, 'd'},
+            {0, 0, 0, 0}
+        };
+
+        int c = getopt_long(argc, argv, "?do:", long_options, NULL);
+        if(c == -1)
+            break;
+        switch(c)
+        {
+            case -1:
+                break;
+            case 'd':
+                g_debug = true;
+                break;
+            case '?':
+                usage();
+                break;
+            case 'o':
+                g_out_prefix = optarg;
+                break;
+            default:
+                abort();
+        }
+    }
+
+    if(optind != argc - 1)
+        usage();
+
+    FILE *f = fopen(argv[optind], "rb");
+    if(f == NULL)
+    {
+        printf("Cannot open file for reading: %m\n");
+        return 1;
+    }
+
+    enum samsung_error_t err;
+    struct samsung_firmware_t *fw = samsung_read(s_read, s_printf,
+        f, &err);
+    if(fw == NULL || err != SAMSUNG_SUCCESS)
+    {
+        printf("Error reading firmware: %d\n", err);
+        samsung_free(fw);
+        return 1;
+    }
+    fclose(f);
+
+    if(g_out_prefix)
+    {
+        f = fopen(g_out_prefix, "wb");
+        if(f == NULL)
+        {
+            printf("Cannot open file for writing: %m\n");
+            return 2;
+        }
+        fwrite(fw->data, 1, fw->data_size, f);
+        fclose(f);
+    }
+
+    samsung_free(fw);
+
+    return 0;
+}
diff --git a/utils/samsungtools/samsung.c b/utils/samsungtools/samsung.c
new file mode 100644
index 0000000000..decf34f208
--- /dev/null
+++ b/utils/samsungtools/samsung.c
@@ -0,0 +1,127 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2012 Amaury Pouly
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "samsung.h"
+#include <openssl/md5.h>
+#include <string.h>
+#include <stdlib.h>
+
+#ifndef MIN
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+static uint8_t g_yp_key[128] =
+{
+    0xa3, 0x04, 0xb9, 0xcd, 0x34, 0x13, 0x4a, 0x19, 0x19, 0x35, 0xdf, 0xbb, 0x8f, 0x3d, 0x7f, 0x09,
+    0x42, 0x3c, 0x96, 0xc6, 0x41, 0xa9, 0x95, 0xf1, 0xd0, 0xac, 0x16, 0x37, 0x57, 0x1f, 0x28, 0xe7,
+    0x0b, 0xc2, 0x12, 0x09, 0x39, 0x42, 0xd2, 0x96, 0xf5, 0x00, 0xd2, 0x23, 0xa4, 0x24, 0xe2, 0x8e,
+    0x50, 0x3c, 0x6e, 0x23, 0xeb, 0x68, 0xed, 0x31, 0xb7, 0xee, 0xc0, 0xc7, 0x09, 0xf8, 0x0e, 0x9d,
+    0x51, 0xed, 0x17, 0x95, 0x64, 0x09, 0xe0, 0xf9, 0xf0, 0xef, 0x86, 0xc0, 0x04, 0x46, 0x89, 0x8a,
+    0x6e, 0x27, 0x69, 0xde, 0xc7, 0x9d, 0x1e, 0xee, 0x3c, 0x3f, 0x17, 0x05, 0x44, 0xbb, 0xbb, 0x1d,
+    0x3d, 0x5d, 0x6e, 0xf2, 0xcf, 0x15, 0xd6, 0x3c, 0xcc, 0x7d, 0x67, 0x1a, 0xb8, 0xd2, 0x1b, 0x54,
+    0x97, 0xa2, 0x58, 0x58, 0xf7, 0x4e, 0x5e, 0x50, 0x42, 0x69, 0xdc, 0xe7, 0x3a, 0x87, 0x2e, 0x22
+};
+
+static void cyclic_xor(void *data, int datasize, void *xor, int xorsize)
+{
+    for(int i = 0; i < datasize; i++)
+        *(uint8_t *)(data + i) ^= *(uint8_t *)(xor + (i % xorsize));
+}
+
+struct samsung_firmware_t *samsung_read(samsung_read_t read,
+    samsung_printf_t printf, void *user, enum samsung_error_t *err)
+{
+    struct yp_header_t yp_hdr;
+    struct yp_md5_t yp_md5;
+
+    /* read and check header */
+    if(read(user, 0, &yp_hdr, sizeof(yp_hdr)) != sizeof(yp_hdr))
+    {
+        printf(user, true, "Cannot read YP header\n");
+        *err = SAMSUNG_READ_ERROR;
+        return NULL;
+    }
+    if(strncmp(yp_hdr.signature, YP_SIGNATURE, sizeof(yp_hdr.signature)) != 0)
+    {
+        printf(user, true, "Bad YP signature\n");
+        *err = SAMSUNG_FORMAT_ERROR;
+        return NULL;
+    }
+
+    printf(user, false, "Model: %s\n", yp_hdr.model);
+    printf(user, false, "Version: %s %s %s\n", yp_hdr.version, yp_hdr.region, yp_hdr.extra);
+
+    /* allocate and read data */
+    struct samsung_firmware_t *fw = malloc(sizeof(struct samsung_firmware_t));
+    memset(fw, 0, sizeof(struct samsung_firmware_t));
+    fw->data_size = yp_hdr.datasize;
+    fw->data = malloc(fw->data_size);
+    strncpy(fw->version, yp_hdr.version, sizeof(yp_hdr.version));
+    strncpy(fw->region, yp_hdr.region, sizeof(yp_hdr.region));
+    strncpy(fw->extra, yp_hdr.extra, sizeof(yp_hdr.extra));
+    strncpy(fw->model, yp_hdr.model, sizeof(yp_hdr.model));
+
+    if(read(user, sizeof(yp_hdr), fw->data, fw->data_size) != fw->data_size)
+    {
+        printf(user, true, "Cannot read data\n");
+        *err = SAMSUNG_READ_ERROR;
+        samsung_free(fw);
+        return NULL;
+    }
+
+    /* read and check MD5 */
+    if(read(user, yp_hdr.datasize + sizeof(yp_hdr), &yp_md5, sizeof(yp_md5)) != sizeof(yp_md5))
+    {
+        printf(user, true, "Cannot read MD5 sum\n");
+        *err = SAMSUNG_READ_ERROR;
+        samsung_free(fw);
+        return NULL;
+    }
+
+    uint8_t actual_md5[MD5_DIGEST_LENGTH];
+    MD5_CTX c;
+    MD5_Init(&c);
+    MD5_Update(&c, fw->data, fw->data_size);
+    MD5_Final(actual_md5, &c);
+
+    if(memcmp(actual_md5, yp_md5.md5, MD5_DIGEST_LENGTH) != 0)
+    {
+        printf(user, true, "MD5 mismatch\n");
+        *err = SAMSUNG_MD5_ERROR;
+        samsung_free(fw);
+        return NULL;
+    }
+
+    /* decrypt */
+    cyclic_xor(fw->data, fw->data_size, g_yp_key, sizeof(g_yp_key));
+
+    /* success ! */
+    *err = SAMSUNG_SUCCESS;
+    return fw;
+}
+
+void samsung_free(struct samsung_firmware_t *fw)
+{
+    if(fw)
+    {
+        free(fw->data);
+        free(fw);
+    }
+}
diff --git a/utils/samsungtools/samsung.h b/utils/samsungtools/samsung.h
new file mode 100644
index 0000000000..4336e02651
--- /dev/null
+++ b/utils/samsungtools/samsung.h
@@ -0,0 +1,78 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2012 Amaury Pouly
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#ifndef __SAMSUNG_H__
+#define __SAMSUNG_H__
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/**
+ * Low-Level
+ */
+
+struct yp_header_t
+{
+    char signature[12];
+    uint32_t pad;
+    char version[8];
+    char region[4];
+    char extra[4];
+    char model[20];
+    uint32_t datasize;
+} __attribute__((packed));
+
+struct yp_md5_t
+{
+    uint8_t md5[16];
+} __attribute__((packed));
+
+#define YP_SIGNATURE    "SAMSUNG YEPP"
+
+/**
+ * API
+ */
+
+struct samsung_firmware_t
+{
+    char version[8];
+    char region[4];
+    char extra[4];
+    char model[20];
+    void *data;
+    int data_size;
+};
+
+enum samsung_error_t
+{
+    SAMSUNG_SUCCESS = 0,
+    SAMSUNG_READ_ERROR = -1,
+    SAMSUNG_FORMAT_ERROR = -2,
+    SAMSUNG_MD5_ERROR = -3,
+};
+
+typedef int (*samsung_read_t)(void *user, int offset, void *buffer, int size);
+typedef void (*samsung_printf_t)(void *user, bool error, const char *fmt, ...);
+
+struct samsung_firmware_t *samsung_read(samsung_read_t read,
+    samsung_printf_t printf, void *user, enum samsung_error_t *err);
+void samsung_free(struct samsung_firmware_t *fw);
+
+#endif /* __SAMSUNG_H__ */