Merge pull request #63 from luken11/signing-fast-path

Add fast path for apps that are already signed with a custom root

Helper/main.m

@@ -8,53 +8,10 @@
 #import <objc/runtime.h>
 #import "CoreServices.h"
 #import "Shared.h"
-#import <mach-o/getsect.h>
-#import <mach-o/dyld.h>
-#import <mach/mach.h>
-#import <mach-o/loader.h>
-#import <mach-o/nlist.h>
-#import <mach-o/reloc.h>
-#import <mach-o/dyld_images.h>
-#import <mach-o/fat.h>
 #import <sys/utsname.h>
 
 #import <SpringBoardServices/SpringBoardServices.h>
-
+#import <Security/Security.h>
-#ifdef __LP64__
-#define segment_command_universal segment_command_64
-#define mach_header_universal mach_header_64
-#define MH_MAGIC_UNIVERSAL MH_MAGIC_64
-#define MH_CIGAM_UNIVERSAL MH_CIGAM_64
-#else
-#define segment_command_universal segment_command
-#define mach_header_universal mach_header
-#define MH_MAGIC_UNIVERSAL MH_MAGIC
-#define MH_CIGAM_UNIVERSAL MH_CIGAM
-#endif
-
-#define SWAP32(x) ((((x) & 0xff000000) >> 24) | (((x) & 0xff0000) >> 8) | (((x) & 0xff00) << 8) | (((x) & 0xff) << 24))
-uint32_t s32(uint32_t toSwap, BOOL shouldSwap)
-{
-	return shouldSwap ? SWAP32(toSwap) : toSwap;
-}
-
-#define CPU_SUBTYPE_ARM64E_NEW_ABI 0x80000002
-
-struct CSSuperBlob {
-	uint32_t magic;
-	uint32_t length;
-	uint32_t count;
-};
-
-struct CSBlob {
-	uint32_t type;
-	uint32_t offset;
-};
-
-#define CS_MAGIC_EMBEDDED_SIGNATURE 0xfade0cc0
-#define CS_MAGIC_EMBEDDED_SIGNATURE_REVERSED 0xc00cdefa
-#define CS_MAGIC_EMBEDDED_ENTITLEMENTS 0xfade7171
-
 
 extern mach_msg_return_t SBReloadIconForIdentifier(mach_port_t machport, const char* identifier);
 @interface SBSHomeScreenService : NSObject
@@ -65,6 +22,26 @@ extern NSString* BKSOpenApplicationOptionKeyActivateForEvent;
 
 extern void BKSTerminateApplicationForReasonAndReportWithDescription(NSString *bundleID, int reasonID, bool report, NSString *description);
 
+
+typedef CF_OPTIONS(uint32_t, SecCSFlags) {
+    kSecCSDefaultFlags = 0
+};
+
+
+#define kSecCSRequirementInformation 1 << 2
+#define kSecCSSigningInformation 1 << 1
+
+typedef struct __SecCode const *SecStaticCodeRef;
+
+extern CFStringRef kSecCodeInfoEntitlementsDict;
+extern CFStringRef kSecCodeInfoCertificates;
+extern CFStringRef kSecPolicyAppleiPhoneApplicationSigning;
+extern CFStringRef kSecPolicyLeafMarkerOid;
+
+OSStatus SecStaticCodeCreateWithPathAndAttributes(CFURLRef path, SecCSFlags flags, CFDictionaryRef attributes, SecStaticCodeRef *staticCode);
+OSStatus SecCodeCopySigningInformation(SecStaticCodeRef code, SecCSFlags flags, CFDictionaryRef *information);
+CFDataRef SecCertificateCopyExtensionValue(SecCertificateRef certificate, CFTypeRef extensionOID, bool *isCritical);
+
 #define kCFPreferencesNoContainer CFSTR("kCFPreferencesNoContainer")
 
 typedef CFPropertyListRef (*_CFPreferencesCopyValueWithContainerType)(CFStringRef key, CFStringRef applicationID, CFStringRef userName, CFStringRef hostName, CFStringRef containerPath);
@@ -221,118 +198,189 @@ int runLdid(NSArray* args, NSString** output, NSString** errorOutput)
 	return WEXITSTATUS(status);
 }
 
-NSDictionary* dumpEntitlements(NSString* binaryPath)
+SecStaticCodeRef getStaticCodeRef(NSString *binaryPath)
 {
-	char* entitlementsData = NULL;
-	uint32_t entitlementsLength = 0;
     
-	FILE* machoFile = fopen(binaryPath.UTF8String, "rb");
+    if(binaryPath == nil)
-	struct mach_header_universal header;
+    {
-	fread(&header,sizeof(header),1,machoFile);
+        return NULL;
+    }
     
-	uint32_t archOffset = 0;
+    CFURLRef binaryURL = CFURLCreateWithFileSystemPath(kCFAllocatorDefault, (__bridge CFStringRef)binaryPath, kCFURLPOSIXPathStyle, false);
+    if(binaryURL == NULL)
+    {
+        NSLog(@"[getStaticCodeRef] failed to get URL to binary %@", binaryPath);
+        return NULL;
+    }
     
-	// Get arch offset if FAT binary
+    SecStaticCodeRef codeRef = NULL;
-	if(header.magic == FAT_MAGIC || header.magic == FAT_CIGAM)
+    OSStatus result;
-	{
-		fseek(machoFile,0,SEEK_SET);
     
-		struct fat_header fatHeader;
+    result = SecStaticCodeCreateWithPathAndAttributes(binaryURL, kSecCSDefaultFlags, NULL, &codeRef);
-		fread(&fatHeader,sizeof(fatHeader),1,machoFile);
     
-		BOOL swpFat = fatHeader.magic == FAT_CIGAM;
+    CFRelease(binaryURL);
     
-		for(int i = 0; i < s32(fatHeader.nfat_arch, swpFat); i++)
+    if(result != errSecSuccess)
-		{
+    {
-			struct fat_arch fatArch;
+        NSLog(@"[getStaticCodeRef] failed to create static code for binary %@", binaryPath);
-			fseek(machoFile,sizeof(fatHeader) + sizeof(fatArch) * i,SEEK_SET);
+        return NULL;
-			fread(&fatArch,sizeof(fatArch),1,machoFile);
+    }
         
-			if(s32(fatArch.cputype, swpFat) != CPU_TYPE_ARM64)
+    return codeRef;
-			{
+}
-				continue;
-			}
 
-			archOffset = s32(fatArch.offset, swpFat);
+NSDictionary* dumpEntitlements(SecStaticCodeRef codeRef)
-			break;
+{
-		}
-	}
     
-	fseek(machoFile,archOffset,SEEK_SET);
+    if(codeRef == NULL)
-	fread(&header,sizeof(header),1,machoFile);
+    {
+        NSLog(@"[dumpEntitlements] attempting to dump entitlements without a StaticCodeRef");
+        return nil;
+    }
     
-	if(header.magic == MH_MAGIC_UNIVERSAL || header.magic == MH_CIGAM_UNIVERSAL)
+    CFDictionaryRef signingInfo = NULL;
-	{
+    OSStatus result;
-		BOOL swp = header.magic == MH_CIGAM_UNIVERSAL;
-		// This code is cursed, don't stare at it too long or it will stare back at you
-		uint32_t offset = archOffset + sizeof(header);
-		for(int c = 0; c < s32(header.ncmds, swp); c++)
-		{
-			fseek(machoFile,offset,SEEK_SET);
-			struct load_command cmd;
-			fread(&cmd,sizeof(cmd),1,machoFile);
-			uint32_t normalizedCmd = s32(cmd.cmd,swp);
-			if(normalizedCmd == LC_CODE_SIGNATURE)
-			{
-				struct linkedit_data_command codeSignCommand;
-				fseek(machoFile,offset,SEEK_SET);
-				fread(&codeSignCommand,sizeof(codeSignCommand),1,machoFile);
-				uint32_t codeSignCmdOffset = archOffset + s32(codeSignCommand.dataoff, swp);
-				fseek(machoFile, codeSignCmdOffset, SEEK_SET);
-				struct CSSuperBlob superBlob;
-				fread(&superBlob, sizeof(superBlob), 1, machoFile);
-				if(SWAP32(superBlob.magic) == CS_MAGIC_EMBEDDED_SIGNATURE) // YES starting here everything is swapped no matter if CIGAM or MAGIC...
-				{
-					uint32_t itemCount = SWAP32(superBlob.count);
-					for(int i = 0; i < itemCount; i++)
-					{
-						fseek(machoFile, codeSignCmdOffset + sizeof(superBlob) + i * sizeof(struct CSBlob),SEEK_SET);
-						struct CSBlob blob;
-						fread(&blob, sizeof(struct CSBlob), 1, machoFile);
-						fseek(machoFile, codeSignCmdOffset + SWAP32(blob.offset),SEEK_SET);
-						uint32_t blobMagic;
-						fread(&blobMagic, sizeof(uint32_t), 1, machoFile);
-						if(SWAP32(blobMagic) == CS_MAGIC_EMBEDDED_ENTITLEMENTS)
-						{
-							uint32_t entitlementsLengthTmp;
-							fread(&entitlementsLengthTmp, sizeof(uint32_t), 1, machoFile);
-							entitlementsLength = SWAP32(entitlementsLengthTmp);
-							entitlementsData = malloc(entitlementsLength - 8);
-							fread(&entitlementsData[0], entitlementsLength - 8, 1, machoFile);
-							break;
-						}
-					}
-				}
     
-				break;
+    result = SecCodeCopySigningInformation(codeRef, kSecCSRequirementInformation, &signingInfo);
-			}
     
-			offset += cmd.cmdsize;
+    if(result != errSecSuccess)
-		}
+    {
-	}
+        NSLog(@"[dumpEntitlements] failed to copy signing info from static code");
+        return nil;
+    }
     
-	fclose(machoFile);
+    NSDictionary *entitlementsNSDict = nil;
     
-	NSData* entitlementsNSData = nil;
+    CFDictionaryRef entitlements = CFDictionaryGetValue(signingInfo, kSecCodeInfoEntitlementsDict);
+    if(entitlements == NULL)
+    {
+        NSLog(@"[dumpEntitlements] no entitlements specified");
+    }
+    else if(CFGetTypeID(entitlements) != CFDictionaryGetTypeID())
+    {
+        NSLog(@"[dumpEntitlements] invalid entitlements");
+    }
+    else
+    {
+        entitlementsNSDict = (__bridge NSDictionary *)(entitlements);
+        NSLog(@"[dumpEntitlements] dumped %@", entitlementsNSDict);
+    }
     
-	if(entitlementsData)
+    CFRelease(signingInfo);
-	{
+    return entitlementsNSDict;
-		entitlementsNSData = [NSData dataWithBytes:entitlementsData length:entitlementsLength];
+}
-		free(entitlementsData);
-	}
 
-	if(entitlementsNSData)
+NSDictionary* dumpEntitlementsFromBinaryAtPath(NSString *binaryPath)
-	{
+{
-		NSDictionary* plist = [NSPropertyListSerialization propertyListWithData:entitlementsNSData options:NSPropertyListImmutable format:nil error:nil];
+    // This function is intended for one-shot checks. Main-event functions should retain/release their own SecStaticCodeRefs
-		NSLog(@"%@ dumped entitlements %@", binaryPath, plist);
-		return plist;
-	}
-	else
-	{
-		NSLog(@"Failed to dump entitlements of %@... This is bad", binaryPath);
-	}
     
-	return nil;
+    if(binaryPath == nil)
+    {
+        return nil;
+    }
+    
+    SecStaticCodeRef codeRef = getStaticCodeRef(binaryPath);
+    if(codeRef == NULL)
+    {
+        return nil;
+    }
+    
+    NSDictionary *entitlements = dumpEntitlements(codeRef);
+    CFRelease(codeRef);
+    
+    return entitlements;
+}
+
+BOOL certificateHasDataForExtensionOID(SecCertificateRef certificate, CFStringRef oidString)
+{
+    
+    if(certificate == NULL || oidString == NULL)
+    {
+        NSLog(@"[certificateHasDataForExtensionOID] attempted to check null certificate or OID");
+        return NO;
+    }
+    
+    CFDataRef extensionData = SecCertificateCopyExtensionValue(certificate, oidString, NULL);
+    if(extensionData != NULL)
+    {
+        CFRelease(extensionData);
+        return YES;
+    }
+    
+    return NO;
+}
+
+BOOL codeCertChainContainsFakeAppStoreExtensions(SecStaticCodeRef codeRef)
+{
+    
+    if(codeRef == NULL)
+    {
+        NSLog(@"[codeCertChainContainsFakeAppStoreExtensions] attempted to check cert chain of null static code object");
+        return NO;
+    }
+    
+    CFDictionaryRef signingInfo = NULL;
+    OSStatus result;
+  
+    result = SecCodeCopySigningInformation(codeRef, kSecCSSigningInformation, &signingInfo);
+    
+    if(result != errSecSuccess)
+    {
+        NSLog(@"[codeCertChainContainsFakeAppStoreExtensions] failed to copy signing info from static code");
+        return NO;
+    }
+    
+    CFArrayRef certificates = CFDictionaryGetValue(signingInfo, kSecCodeInfoCertificates);
+
+    // If we match the standard Apple policy, we are signed properly, but we haven't been deliberately signed with a custom root
+    
+    SecPolicyRef genuineApplePolicy = SecPolicyCreateWithProperties(kSecPolicyAppleiPhoneApplicationSigning, NULL);
+    SecTrustRef genuineAppleTrust = NULL;
+    SecTrustCreateWithCertificates(certificates, genuineApplePolicy, &genuineAppleTrust);
+    
+    if(SecTrustEvaluateWithError(genuineAppleTrust, nil))
+    {
+        CFRelease(genuineAppleTrust);
+        CFRelease(genuineApplePolicy);
+        CFRelease(signingInfo);
+        
+        NSLog(@"[codeCertChainContainsFakeAppStoreExtensions] found certificate extension, but was issued by Apple");
+        return NO;
+    }
+    
+    // We haven't matched Apple, so keep going. Are we using a custom root that would take the App Store fastpath?
+    CFRelease(genuineAppleTrust);
+    CFRelease(genuineApplePolicy);
+    
+    // Cert chain should be of length 3
+    if(CFArrayGetCount(certificates) != 3)
+    {
+        CFRelease(signingInfo);
+        
+        NSLog(@"[codeCertChainContainsFakeAppStoreExtensions] certificate chain length != 3");
+        return NO;
+    }
+    
+    const void *keys[1] = { kSecPolicyLeafMarkerOid };
+    const void *values[1] = { CFSTR("1.2.840.113635.100.6.1.3") };
+    CFDictionaryRef customPolicyOptions = CFDictionaryCreate(NULL, keys, values, 1, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
+    
+    // AppleCodeSigning only checks for the codeSigning EKU by default
+    SecPolicyRef customRootPolicy = SecPolicyCreateWithProperties(kSecPolicyAppleCodeSigning, customPolicyOptions);
+    SecTrustRef customRootTrust = NULL;
+    
+    // Need to add our certificate chain to the anchor as it is expected to be a self-signed root
+    SecTrustCreateWithCertificates(certificates, customRootPolicy, &customRootTrust);
+    SecTrustSetAnchorCertificates(customRootTrust, certificates);
+    
+    BOOL evaluatesToCustomAnchor = SecTrustEvaluateWithError(customRootTrust, nil);
+    
+    CFRelease(customRootTrust);
+    CFRelease(customRootPolicy);
+    CFRelease(customPolicyOptions);
+    
+    CFRelease(signingInfo);
+    return evaluatesToCustomAnchor;
 }
 
 BOOL signApp(NSString* appPath, NSError** error)
@@ -347,12 +395,41 @@ BOOL signApp(NSString* appPath, NSError** error)
 
 	if(![[NSFileManager defaultManager] fileExistsAtPath:executablePath]) return NO;
     
+    NSObject *tsBundleIsPreSigned = appInfoDict[@"TSBundlePreSigned"];
+    if([tsBundleIsPreSigned isKindOfClass:[NSNumber class]])
+    {
+        
+        // if TSBundlePreSigned = YES, this bundle has been externally signed so we can skip over signing it now
+        NSNumber *tsBundleIsPreSignedNum = (NSNumber *)tsBundleIsPreSigned;
+        if([tsBundleIsPreSignedNum boolValue] == YES)
+        {
+            NSLog(@"[signApp] taking fast path for app which declares it has already been signed (%@)", executablePath);
+            return YES;
+        }
+    }
+    
+    SecStaticCodeRef codeRef = getStaticCodeRef(executablePath);
+    if(codeRef == NULL)
+    {
+        NSLog(@"[signApp] failed to get static code, can't derive entitlements from %@", executablePath);
+        return NO;
+    }
+    
+    if(codeCertChainContainsFakeAppStoreExtensions(codeRef))
+    {
+        NSLog(@"[signApp] taking fast path for app signed using a custom root certificate (%@)", executablePath);
+        CFRelease(codeRef);
+        return YES;
+    }
+
 	NSString* certPath = [trollStoreAppPath() stringByAppendingPathComponent:@"cert.p12"];
 	NSString* certArg = [@"-K" stringByAppendingPathComponent:certPath];
 	NSString* errorOutput;
 	int ldidRet;
 
-	NSDictionary* entitlements = dumpEntitlements(executablePath);
+    NSDictionary* entitlements = dumpEntitlements(codeRef);
+    CFRelease(codeRef);
+    
 	if(!entitlements)
 	{
 		NSLog(@"app main binary has no entitlements, signing app with fallback entitlements...");

Helper/uicache.m

@@ -6,7 +6,7 @@
 
 // uicache on steroids
 
-extern NSDictionary* dumpEntitlements(NSString* binaryPath);
+extern NSDictionary* dumpEntitlementsFromBinaryAtPath(NSString* binaryPath);
 
 NSDictionary* constructGroupsContainersForEntitlements(NSDictionary* entitlements, BOOL systemGroups)
 {
@@ -118,7 +118,7 @@ void registerPath(char* cPath, int unregister)
 		// Add entitlements
 
 		NSString* appExecutablePath = [path stringByAppendingPathComponent:appInfoPlist[@"CFBundleExecutable"]];
-		NSDictionary* entitlements = dumpEntitlements(appExecutablePath);
+		NSDictionary* entitlements = dumpEntitlementsFromBinaryAtPath(appExecutablePath);
 		if(entitlements)
 		{
 			dictToRegister[@"Entitlements"] = entitlements;
@@ -188,7 +188,7 @@ void registerPath(char* cPath, int unregister)
 			// Add entitlements
 
 			NSString* pluginExecutablePath = [pluginPath stringByAppendingPathComponent:pluginInfoPlist[@"CFBundleExecutable"]];
-			NSDictionary* pluginEntitlements = dumpEntitlements(pluginExecutablePath);
+			NSDictionary* pluginEntitlements = dumpEntitlementsFromBinaryAtPath(pluginExecutablePath);
 			if(pluginEntitlements)
 			{
 				pluginDict[@"Entitlements"] = pluginEntitlements;