twinstall.cpp

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

#include <string.h>
#include <stdio.h>

#include "common.h"
#include "twmincrypt/twrsa.h"
#include "twmincrypt/twsha.h"
#include "minui/minui.h"
#include "minzip/SysUtil.h"
#include "minzip/Zip.h"
#include "mtdutils/mounts.h"
#include "mtdutils/mtdutils.h"
#include "roots.h"
#include "verifier.h"
#include "ui.h"
#include "variables.h"
#include "data.hpp"
#include "partitions.hpp"

extern "C" {
#include "extra-functions.h"
int __system(const char *command);
};

extern RecoveryUI* ui;

#define ASSUMED_UPDATE_BINARY_NAME  "META-INF/com/google/android/update-binary"
#define PUBLIC_KEYS_FILE "/res/keys"

// Default allocation of progress bar segments to operations
static const int VERIFICATION_PROGRESS_TIME = 60;
static const float VERIFICATION_PROGRESS_FRACTION = 0.25;
static const float DEFAULT_FILES_PROGRESS_FRACTION = 0.4;
static const float DEFAULT_IMAGE_PROGRESS_FRACTION = 0.1;

enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT };

// Look for an RSA signature embedded in the .ZIP file comment given
// the path to the zip.  Verify it matches one of the given public
// keys.
//
// Return VERIFY_SUCCESS, VERIFY_FAILURE (if any error is encountered
// or no key matches the signature).

int TWverify_file(const char* path, const RSAPublicKey *pKeys, unsigned int numKeys) {
    ui->SetProgress(0.0);

    FILE* f = fopen(path, "rb");
    if (f == NULL) {
        LOGE("failed to open %s (%s)\n", path, strerror(errno));
        return VERIFY_FAILURE;
    }

    // An archive with a whole-file signature will end in six bytes:
    //
    //   (2-byte signature start) $ff $ff (2-byte comment size)
    //
    // (As far as the ZIP format is concerned, these are part of the
    // archive comment.)  We start by reading this footer, this tells
    // us how far back from the end we have to start reading to find
    // the whole comment.

#define FOOTER_SIZE 6

    if (fseek(f, -FOOTER_SIZE, SEEK_END) != 0) {
        LOGE("failed to seek in %s (%s)\n", path, strerror(errno));
        fclose(f);
        return VERIFY_FAILURE;
    }

    unsigned char footer[FOOTER_SIZE];
    if (fread(footer, 1, FOOTER_SIZE, f) != FOOTER_SIZE) {
        LOGE("failed to read footer from %s (%s)\n", path, strerror(errno));
        fclose(f);
        return VERIFY_FAILURE;
    }

    if (footer[2] != 0xff || footer[3] != 0xff) {
        fclose(f);
        return VERIFY_FAILURE;
    }

    size_t comment_size = footer[4] + (footer[5] << 8);
    size_t signature_start = footer[0] + (footer[1] << 8);
    LOGI("comment is %d bytes; signature %d bytes from end\n",
         comment_size, signature_start);

    if (signature_start - FOOTER_SIZE < RSANUMBYTES) {
        // "signature" block isn't big enough to contain an RSA block.
        LOGE("signature is too short\n");
        fclose(f);
        return VERIFY_FAILURE;
    }

#define EOCD_HEADER_SIZE 22

    // The end-of-central-directory record is 22 bytes plus any
    // comment length.
    size_t eocd_size = comment_size + EOCD_HEADER_SIZE;

    if (fseek(f, -eocd_size, SEEK_END) != 0) {
        LOGE("failed to seek in %s (%s)\n", path, strerror(errno));
        fclose(f);
        return VERIFY_FAILURE;
    }

    // Determine how much of the file is covered by the signature.
    // This is everything except the signature data and length, which
    // includes all of the EOCD except for the comment length field (2
    // bytes) and the comment data.
    size_t signed_len = ftell(f) + EOCD_HEADER_SIZE - 2;

    unsigned char* eocd = (unsigned char*)malloc(eocd_size);
    if (eocd == NULL) {
        LOGE("malloc for EOCD record failed\n");
        fclose(f);
        return VERIFY_FAILURE;
    }
    if (fread(eocd, 1, eocd_size, f) != eocd_size) {
        LOGE("failed to read eocd from %s (%s)\n", path, strerror(errno));
        fclose(f);
        return VERIFY_FAILURE;
    }

    // If this is really is the EOCD record, it will begin with the
    // magic number $50 $4b $05 $06.
    if (eocd[0] != 0x50 || eocd[1] != 0x4b ||
        eocd[2] != 0x05 || eocd[3] != 0x06) {
        LOGE("signature length doesn't match EOCD marker\n");
        fclose(f);
        return VERIFY_FAILURE;
    }

    size_t i;
    for (i = 4; i < eocd_size-3; ++i) {
        if (eocd[i  ] == 0x50 && eocd[i+1] == 0x4b &&
            eocd[i+2] == 0x05 && eocd[i+3] == 0x06) {
            // if the sequence $50 $4b $05 $06 appears anywhere after
            // the real one, minzip will find the later (wrong) one,
            // which could be exploitable.  Fail verification if
            // this sequence occurs anywhere after the real one.
            LOGE("EOCD marker occurs after start of EOCD\n");
            fclose(f);
            return VERIFY_FAILURE;
        }
    }

#define BUFFER_SIZE 4096

    SHA_CTX ctx;
    SHA_init(&ctx);
    unsigned char* buffer = (unsigned char*)malloc(BUFFER_SIZE);
    if (buffer == NULL) {
        LOGE("failed to alloc memory for sha1 buffer\n");
        fclose(f);
        return VERIFY_FAILURE;
    }

    double frac = -1.0;
    size_t so_far = 0;
    fseek(f, 0, SEEK_SET);
    while (so_far < signed_len) {
        size_t size = BUFFER_SIZE;
        if (signed_len - so_far < size) size = signed_len - so_far;
        if (fread(buffer, 1, size, f) != size) {
            LOGE("failed to read data from %s (%s)\n", path, strerror(errno));
            fclose(f);
            return VERIFY_FAILURE;
        }
        SHA_update(&ctx, buffer, size);
        so_far += size;
        double f = so_far / (double)signed_len;
        if (f > frac + 0.02 || size == so_far) {
            ui->SetProgress(f);
            frac = f;
        }
    }
    fclose(f);
    free(buffer);

    const uint8_t* sha1 = SHA_final(&ctx);
    for (i = 0; i < numKeys; ++i) {
        // The 6 bytes is the "(signature_start) $ff $ff (comment_size)" that
        // the signing tool appends after the signature itself.
        if (RSA_verify(pKeys+i, eocd + eocd_size - 6 - RSANUMBYTES,
                       RSANUMBYTES, sha1)) {
            LOGI("whole-file signature verified against key %d\n", i);
            free(eocd);
            return VERIFY_SUCCESS;
        }
    }
    free(eocd);
    LOGE("failed to verify whole-file signature\n");
    return VERIFY_FAILURE;
}

// If the package contains an update binary, extract it and run it.
static int
try_update_binary(const char *path, ZipArchive *zip, int* wipe_cache) {
    const ZipEntry* binary_entry =
            mzFindZipEntry(zip, ASSUMED_UPDATE_BINARY_NAME);
    if (binary_entry == NULL) {
        mzCloseZipArchive(zip);
        return INSTALL_CORRUPT;
    }

    const char* binary = "/tmp/update_binary";
    unlink(binary);
    int fd = creat(binary, 0755);
    if (fd < 0) {
        mzCloseZipArchive(zip);
        LOGE("Can't make %s\n", binary);
        return INSTALL_ERROR;
    }
    bool ok = mzExtractZipEntryToFile(zip, binary_entry, fd);
    close(fd);
    mzCloseZipArchive(zip);

    if (!ok) {
        LOGE("Can't copy %s\n", ASSUMED_UPDATE_BINARY_NAME);
        return INSTALL_ERROR;
    }

    int pipefd[2];
    pipe(pipefd);

    // When executing the update binary contained in the package, the
    // arguments passed are:
    //
    //   - the version number for this interface
    //
    //   - an fd to which the program can write in order to update the
    //     progress bar.  The program can write single-line commands:
    //
    //        progress <frac> <secs>
    //            fill up the next <frac> part of of the progress bar
    //            over <secs> seconds.  If <secs> is zero, use
    //            set_progress commands to manually control the
    //            progress of this segment of the bar
    //
    //        set_progress <frac>
    //            <frac> should be between 0.0 and 1.0; sets the
    //            progress bar within the segment defined by the most
    //            recent progress command.
    //
    //        firmware <"hboot"|"radio"> <filename>
    //            arrange to install the contents of <filename> in the
    //            given partition on reboot.
    //
    //            (API v2: <filename> may start with "PACKAGE:" to
    //            indicate taking a file from the OTA package.)
    //
    //            (API v3: this command no longer exists.)
    //
    //        ui_print <string>
    //            display <string> on the screen.
    //
    //   - the name of the package zip file.
    //

    const char** args = (const char**)malloc(sizeof(char*) * 5);
    args[0] = binary;
    args[1] = EXPAND(RECOVERY_API_VERSION);   // defined in Android.mk
    char* temp = (char*)malloc(10);
    sprintf(temp, "%d", pipefd[1]);
    args[2] = temp;
    args[3] = (char*)path;
    args[4] = NULL;

    pid_t pid = fork();
    if (pid == 0) {
        close(pipefd[0]);
        execv(binary, (char* const*)args);
        fprintf(stdout, "E:Can't run %s (%s)\n", binary, strerror(errno));
        _exit(-1);
    }
    close(pipefd[1]);

    *wipe_cache = 0;

    char buffer[1024];
    FILE* from_child = fdopen(pipefd[0], "r");
    while (fgets(buffer, sizeof(buffer), from_child) != NULL) {
        char* command = strtok(buffer, " \n");
        if (command == NULL) {
            continue;
        } else if (strcmp(command, "progress") == 0) {
            char* fraction_s = strtok(NULL, " \n");
            char* seconds_s = strtok(NULL, " \n");

            float fraction = strtof(fraction_s, NULL);
            int seconds = strtol(seconds_s, NULL, 10);

            ui->ShowProgress(fraction * (1-VERIFICATION_PROGRESS_FRACTION), seconds);
        } else if (strcmp(command, "set_progress") == 0) {
            char* fraction_s = strtok(NULL, " \n");
            float fraction = strtof(fraction_s, NULL);
            ui->SetProgress(fraction);
        } else if (strcmp(command, "ui_print") == 0) {
            char* str = strtok(NULL, "\n");
            if (str) {
                ui->Print("%s", str);
            } else {
                ui->Print("\n");
            }
        } else if (strcmp(command, "wipe_cache") == 0) {
            *wipe_cache = 1;
        } else if (strcmp(command, "clear_display") == 0) {
            //ui->SetBackground(RecoveryUI::NONE);
        } else {
            LOGE("unknown command [%s]\n", command);
        }
    }
    fclose(from_child);

    int status;
    waitpid(pid, &status, 0);
    if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
        LOGE("Error in %s\n(Status %d)\n", path, WEXITSTATUS(status));
        return INSTALL_ERROR;
    }

    return INSTALL_SUCCESS;
}

// Reads a file containing one or more public keys as produced by
// DumpPublicKey:  this is an RSAPublicKey struct as it would appear
// as a C source literal, eg:
//
//  "{64,0xc926ad21,{1795090719,...,-695002876},{-857949815,...,1175080310}}"
//
// (Note that the braces and commas in this example are actual
// characters the parser expects to find in the file; the ellipses
// indicate more numbers omitted from this example.)
//
// The file may contain multiple keys in this format, separated by
// commas.  The last key must not be followed by a comma.
//
// Returns NULL if the file failed to parse, or if it contain zero keys.
static RSAPublicKey*
load_keys(const char* filename, int* numKeys) {
    RSAPublicKey* out = NULL;
    *numKeys = 0;

    FILE* f = fopen(filename, "r");
    if (f == NULL) {
        LOGE("opening %s: %s\n", filename, strerror(errno));
        goto exit;
    }

    {
        int i;
        bool done = false;
        while (!done) {
            ++*numKeys;
            out = (RSAPublicKey*)realloc(out, *numKeys * sizeof(RSAPublicKey));
            RSAPublicKey* key = out + (*numKeys - 1);
            if (fscanf(f, " { %i , 0x%x , { %u",
                       &(key->len), &(key->n0inv), &(key->n[0])) != 3) {
                goto exit;
            }
            if (key->len != RSANUMWORDS) {
                LOGE("key length (%d) does not match expected size\n", key->len);
                goto exit;
            }
            for (i = 1; i < key->len; ++i) {
                if (fscanf(f, " , %u", &(key->n[i])) != 1) goto exit;
            }
            if (fscanf(f, " } , { %u", &(key->rr[0])) != 1) goto exit;
            for (i = 1; i < key->len; ++i) {
                if (fscanf(f, " , %u", &(key->rr[i])) != 1) goto exit;
            }
            fscanf(f, " } } ");

            // if the line ends in a comma, this file has more keys.
            switch (fgetc(f)) {
            case ',':
                // more keys to come.
                break;

            case EOF:
                done = true;
                break;

            default:
                LOGE("unexpected character between keys\n");
                goto exit;
            }
        }
    }

    fclose(f);
    return out;

exit:
    if (f) fclose(f);
    free(out);
    *numKeys = 0;
    return NULL;
}

char* get_path (char* path) {
        char *s;

        /* Go to the end of the string.  */
        s = path + strlen(path) - 1;

        /* Strip off trailing /s (unless it is also the leading /).  */
        while (path < s && s[0] == '/')
                s--;

        /* Strip the last component.  */
        while (path <= s && s[0] != '/')
                s--;

        while (path < s && s[0] == '/')
                s--;

        if (s < path)
                return (char*)(".");

        s[1] = '\0';
	return path;
}

/*
    Checks md5 for a path
    Return values:
        -1 : MD5 does not exist
        0 : Failed
        1 : Success
*/
int check_md5(const char* path) {
	FILE* fp;
	char command[255], line[512], actual_md5[512], md5[512];
	char md5file[PATH_MAX + 40];
	char *ptr;
	unsigned int line_len, index = 0;
	struct stat st;

	// Check to see if the filename.zip.md5 file exists
	strcpy(md5file, path);
    strcat(md5file, ".md5");
	if (stat(md5file, &st) != 0)
		return -1; // no MD5 file found

	// Dump the md5 of the zip to a text file for reading
	sprintf(command, "md5sum '%s' > /tmp/md5output.txt", path);
	__system(command);
	fp = fopen("/tmp/md5output.txt", "rt");
	if (fp == NULL) {
		LOGI("Unable to open /tmp/md5output.txt.\n");
		return false;
	}

	while (fgets(line, sizeof(line), fp) != NULL)
	{
		line_len = strlen(line);
		for (index = 0; index < line_len; index++) {
			if (line[index] <= 32)
				line[index] = '\0';
		}
		strcpy(actual_md5, line);
		break;
	}
	fclose(fp);

	// Read the filename.zip.md5 file
	fp = fopen(md5file, "rt");
	if (fp == NULL) {
		LOGI("Unable to open '%s'.\n", md5file);
		return false;
	}

	while (fgets(line, sizeof(line), fp) != NULL)
	{
		line_len = strlen(line);
		for (index = 0; index < line_len; index++) {
			if (line[index] <= 32)
				line[index] = '\0';
		}
		strcpy(md5, line);
		break;
	}
	fclose(fp);

	// Comare the 2 MD5 values
	if (strcmp(actual_md5, md5) == 0)
		return 1;
	LOGI("MD5 did not match: '%s' != '%s'\n", actual_md5, md5);
	return 0;
}

extern "C" int TWinstall_zip(const char* path, int* wipe_cache) {
	int err, zip_verify, md5_return, md5_verify;

	ui_print("Installing '%s'...\n", path);

	if (!PartitionManager.Mount_By_Path(path, 0)) {
		LOGE("Failed to mount '%s'\n", path);
		return -1;
	}

	ui_print("Checking for MD5 file...\n");
	md5_return = check_md5(path);
	if (md5_return == 0) {
		// MD5 did not match.
		LOGE("Zip MD5 does not match.\nUnable to install zip.\n");
		return INSTALL_CORRUPT;
	} else if (md5_return == -1) {
		DataManager::GetValue(TW_FORCE_MD5_CHECK_VAR, md5_verify);
		if (md5_verify == 1) {
			// Forced MD5 checking is on and no MD5 file found.
			LOGE("No MD5 file found for '%s'.\nDisable force MD5 check to avoid this error.\n", path);
			return INSTALL_CORRUPT;
		} else
			ui_print("No MD5 file found, this is not an error.\n");
	} else if (md5_return == 1)
		ui_print("Zip MD5 matched.\n"); // MD5 found and matched.

	DataManager::GetValue(TW_SIGNED_ZIP_VERIFY_VAR, zip_verify);
	if (zip_verify) {
		ui_print("Verifying zip signature...\n");
		int numKeys;
		RSAPublicKey* loadedKeys = load_keys(PUBLIC_KEYS_FILE, &numKeys);
		if (loadedKeys == NULL) {
			LOGE("Failed to load keys\n");
			return -1;
		}
		LOGI("%d key(s) loaded from %s\n", numKeys, PUBLIC_KEYS_FILE);

		// Give verification half the progress bar...
		ui->Print("Verifying update package...\n");
		ui->SetProgressType(RecoveryUI::DETERMINATE);
		ui->ShowProgress(VERIFICATION_PROGRESS_FRACTION, VERIFICATION_PROGRESS_TIME);

		err = TWverify_file(path, loadedKeys, numKeys);
		free(loadedKeys);
		LOGI("verify_file returned %d\n", err);
		if (err != VERIFY_SUCCESS) {
			LOGE("signature verification failed\n");
			return -1;
		}
	}
	/* Try to open the package.
     */
    ZipArchive zip;
    err = mzOpenZipArchive(path, &zip);
    if (err != 0) {
        LOGE("Can't open %s\n(%s)\n", path, err != -1 ? strerror(err) : "bad");
        return INSTALL_CORRUPT;
    }

    /* Verify and install the contents of the package.
     */
    return try_update_binary(path, &zip, wipe_cache);
}