SecurityTool/macOS/trusted_cert_ssl.m

   1 /*
   2  * Copyright (c) 2019 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  *
  23  * verify_ssl.m
  24  */
  25
  26
  27 #import "trusted_cert_ssl.h"
  28 #include <Foundation/Foundation.h>
  29 #include <CoreServices/CoreServices.h>
  30
  31 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
  32
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36
  37 #if TARGET_OS_MAC
  38 #include <Security/oidscert.h>
  39 #include <Security/oidsattr.h>
  40 #include <Security/oidsalg.h>
  41 #include <Security/x509defs.h>
  42 #include <Security/cssmapi.h>
  43 #include <Security/cssmapple.h>
  44 #endif
  45
  46 #include <Security/certextensions.h>
  47 #include <Security/SecKeychain.h>
  48 #include <Security/SecKeychainItem.h>
  49 #include <Security/SecImportExport.h>
  50 #include <Security/SecIdentity.h>
  51 #include <Security/SecIdentitySearch.h>
  52 #include <Security/SecKey.h>
  53 #include <Security/SecCertificate.h>
  54 #include <Security/SecTrust.h>
  55
  56 #include <CFNetwork/CFNetwork.h>
  57 #include <SecurityFoundation/SFCertificateData.h>
  58
  59 typedef CFTypeRef CFURLResponseRef;
  60 CFDictionaryRef _CFURLResponseGetSSLCertificateContext(CFURLResponseRef);
  61
  62 @interface NSURLResponse (URLResponseInternals)
  63 - (CFURLResponseRef)_CFURLResponse;
  64 @end
  65
  66 @interface NSHTTPURLResponse (HTTPURLResponseInternals)
  67 - (NSArray *)_peerCertificateChain;
  68 @end
  69
  70 @interface NSURLResponse (CertificateUtilities)
  71 - (SecTrustRef)peerTrust;
  72 - (NSArray *)peerCertificates;
  73 @end
  74
  75 @interface CertDownloader : NSObject <NSURLDownloadDelegate>
  76 {
  77     @private
  78     NSURL *_url;
  79     NSURLRequest *_urlReq;
  80     NSURLResponse *_urlRsp;
  81     NSURLDownload *_urlDL;
  82     SecTrustRef _trust;
  83     BOOL _finished;
  84 }
  85
  86 - (id)initWithURLString:(const char *)urlstr;
  87 - (void)dealloc;
  88 - (BOOL)finished;
  89 - (void)waitForDownloadToFinish;
  90
  91 - (SecTrustRef)trustReference;
  92
  93 - (void)downloadDidFinish:(NSURLDownload *)download;
  94 - (void)download:(NSURLDownload *)download didFailWithError:(NSError *)error;
  95
  96 + (BOOL)isNetworkURL:(const char *)urlstr;
  97
  98 @end
  99
 100 static int _verbose = 0;
 101
 102 #define ANSI_RED     "\x1b[31m"
 103 #define ANSI_GREEN   "\x1b[32m"
 104 #define ANSI_YELLOW  "\x1b[33m"
 105 #define ANSI_BLUE    "\x1b[34m"
 106 #define ANSI_MAGENTA "\x1b[35m"
 107 #define ANSI_CYAN    "\x1b[36m"
 108 #define ANSI_RESET   "\x1b[0m"
 109
 110
 111 @implementation CertDownloader
 112
 113 - (id)initWithURLString:(const char *)urlstr
 114 {
 115     _finished = NO;
 116     _url = [[NSURL alloc] initWithString:[NSString stringWithFormat:@"%s", urlstr]];
 117     _urlReq = [[NSURLRequest alloc] initWithURL:_url];
 118     _urlRsp = nil;
 119     _trust = NULL;
 120
 121     _urlDL = [[NSURLDownload alloc] initWithRequest:_urlReq delegate:self];
 122
 123     fprintf(stdout, "Opening connection to %s\n", urlstr);
 124     fflush(stdout);
 125
 126     return self;
 127 }
 128
 129 - (void)dealloc
 130 {
 131     _urlDL = nil;
 132     _urlReq = nil;
 133     _urlRsp = nil;
 134     _url = nil;
 135     _trust = NULL;
 136 }
 137
 138 - (BOOL)finished
 139 {
 140     return _finished;
 141 }
 142
 143 - (void)waitForDownloadToFinish
 144 {
 145     // cycle the run loop while we're waiting for the _finished flag to be set
 146     NSDate *cycleTime;
 147     while (_finished == NO) {
 148         cycleTime = [NSDate dateWithTimeIntervalSinceNow:0.1];
 149         [[NSRunLoop currentRunLoop] runMode: NSDefaultRunLoopMode beforeDate:cycleTime];
 150     }
 151 }
 152
 153 // NSURLDownloadDelegate delegate methods
 154
 155 - (void)downloadDidFinish:(NSURLDownload *)download
 156 {
 157     if (!_urlRsp) {
 158         fprintf(stdout, "No response received from %s\n", [[_url absoluteString] UTF8String]);
 159         fflush(stdout);
 160     }
 161     _finished = YES;
 162 }
 163
 164 - (void)download:(NSURLDownload *)download didReceiveResponse:(NSURLResponse *)response
 165 {
 166     fprintf(stdout, "Received response from %s\n", [[_url absoluteString] UTF8String]);
 167     fflush(stdout);
 168     _urlRsp = response;
 169 }
 170
 171 - (void)download:(NSURLDownload *)download didFailWithError:(NSError *)error
 172 {
 173     fprintf(stdout, "Failed connection to %s", [[_url absoluteString] UTF8String]);
 174     if (!_verbose) {
 175         fprintf(stdout, " (use -v option to see more information)");
 176     }
 177     fprintf(stdout, "\n");
 178     fflush(stdout);
 179     SecTrustRef tmp = _trust;
 180     _trust = (SecTrustRef)CFBridgingRetain([[error userInfo] objectForKey:@"NSURLErrorFailingURLPeerTrustErrorKey"]);
 181     if (tmp) { CFRelease(tmp); }
 182     _finished = YES;
 183
 184     if (_verbose) {
 185         // dump the userInfo dictionary
 186         NSLog(@"%@", [error userInfo]);
 187     }
 188 }
 189
 190 - (SecTrustRef)trustReference
 191 {
 192     // First, see if we already retained the SecTrustRef, e.g. during a failed connection.
 193     SecTrustRef trust = _trust;
 194     if (!trust) {
 195         // If not, try to obtain the SecTrustRef from the response.
 196         trust = [_urlRsp peerTrust];
 197         if (trust) {
 198             if (_verbose > 1) {
 199                 fprintf(stdout, "Obtained SecTrustRef from the response\n");
 200             }
 201             CFRetain(trust);
 202             _trust = trust;
 203         }
 204     }
 205     if (!trust) {
 206         // We don't have a SecTrustRef, so build one ourselves for this host.
 207         NSString *host = [_url host];
 208         if (_verbose > 1) {
 209             fprintf(stdout, "Building our own SecTrustRef for \"%s\"\n", host ? [host UTF8String] : "<missing host>");
 210         }
 211         SecPolicyRef sslPolicy = SecPolicyCreateSSL(false, (__bridge CFStringRef)host);
 212         SecPolicyRef revPolicy =  SecPolicyCreateRevocation(kSecRevocationUseAnyAvailableMethod);
 213         NSArray *policies = [NSArray arrayWithObjects:(__bridge id)sslPolicy, (__bridge id)revPolicy, nil];
 214         NSArray *certs = [_urlRsp peerCertificates];
 215         if (certs) {
 216             (void)SecTrustCreateWithCertificates((__bridge CFArrayRef)certs, (__bridge CFArrayRef)policies, &trust);
 217             _trust = trust;
 218         }
 219     }
 220
 221     // Ensure that the trust has been evaluated
 222     SecTrustResultType result = kSecTrustResultInvalid;
 223     OSStatus status = SecTrustGetTrustResult(trust, &result);
 224     bool needsEvaluation = (status != errSecSuccess || result == kSecTrustResultInvalid);
 225     if (needsEvaluation) {
 226         status = SecTrustEvaluate(trust, &result);
 227         if (_verbose > 1) {
 228             fprintf(stdout, "%s trust reference (status = %d, trust result = %d)\n",
 229                     (needsEvaluation) ? "Evaluated" : "Checked",
 230                     (int)status, (int)result);
 231         }
 232     }
 233     return trust;
 234 }
 235
 236 + (BOOL)isNetworkURL:(const char *)urlstr
 237 {
 238     if (urlstr) {
 239         NSArray *schemes = @[@"https",@"ldaps"];
 240         NSURL *url = [NSURL URLWithString:[NSString stringWithUTF8String:urlstr]];
 241         if (url && [schemes containsObject:[url scheme]]) {
 242             return YES;
 243         }
 244     }
 245     return NO;
 246 }
 247
 248 @end
 249
 250 @implementation NSURLResponse (CertificateUtilities)
 251
 252 - (SecTrustRef)peerTrust
 253 {
 254     SecTrustRef trust = NULL;
 255
 256     // Obtain the underlying SecTrustRef used by CFNetwork for the connection.
 257     CFDictionaryRef certificateContext = _CFURLResponseGetSSLCertificateContext([self _CFURLResponse]);
 258     if (_verbose && !certificateContext) {
 259         fprintf(stdout, "Unable to get SSL certificate context!\n");
 260         fflush(stdout);
 261     } else {
 262         trust = (SecTrustRef) CFDictionaryGetValue(certificateContext, kCFStreamPropertySSLPeerTrust);
 263     }
 264     if (_verbose && !trust) {
 265         fprintf(stdout, "Unable to get kCFStreamPropertySSLPeerTrust!\n");
 266         fflush(stdout);
 267     }
 268     return trust;
 269 }
 270
 271 - (NSArray *)peerCertificates
 272 {
 273     NSArray *certificateChain = nil;
 274     if ([self isKindOfClass:[NSHTTPURLResponse class]]) {
 275         certificateChain = [(NSHTTPURLResponse *)self _peerCertificateChain];
 276     }
 277     if (_verbose && certificateChain) {
 278         fprintf(stdout, "Peer certificates: ");
 279         fflush(stdout);
 280         CFShow((__bridge CFArrayRef)certificateChain);
 281     }
 282     return certificateChain;
 283 }
 284
 285 @end
 286
 287
 288 static NSString *errorStringForKey(NSString *key)
 289 {
 290     NSString *errstr = nil;
 291     // %%% note: these dictionary keys currently do not have exported constants
 292     if (![key length] || [key isEqualToString:@"StatusCodes"]) {
 293         return errstr; // skip empty and legacy numeric errors
 294     } else if ([key isEqualToString:@"SSLHostname"]) {
 295         errstr = @"Host name not found in Subject Alternative Name extension";
 296     } else if ([key isEqualToString:@"TemporalValidity"]) {
 297         errstr = @"Certificate has expired, or is not yet valid (check date)";
 298     } else if ([key isEqualToString:@"KeySize"]) {
 299         errstr = @"Certificate uses a key size which is considered too weak";
 300     } else if ([key isEqualToString:@"SignatureHashAlgorithms"]) {
 301         errstr = @"Certificate uses a signing algorithm which is considered too weak";
 302     } else if ([key isEqualToString:@"KeyUsage"]) {
 303         errstr = @"The Key Usage extension does not permit this use for the certificate";
 304     } else if ([key isEqualToString:@"ExtendedKeyUsage"]) {
 305         errstr = @"The Extended Key Usage extension does not permit this use for the certificate";
 306     } else if ([key isEqualToString:@"Revocation"]) {
 307         errstr = @"Certificate has been revoked and cannot be used";
 308     } else if ([key isEqualToString:@"BlackListedLeaf"]) {
 309         errstr = @"Certificate has been blocked and cannot be used";
 310     } else if ([key isEqualToString:@"AnchorTrusted"]) {
 311         errstr = @"The root of the certificate chain is not trusted";
 312     } else if ([key isEqualToString:@"MissingIntermediate"]) {
 313         errstr = @"Unable to find next certificate in the chain";
 314     } else if ([key isEqualToString:@"NonEmptySubject"]) {
 315         errstr = @"Certificate has no subject, and SAN is missing or not marked critical";
 316     } else if ([key isEqualToString:@"BasicCertificateProcessing"]) {
 317         errstr = @"Certificate not standards compliant (RFC 5280|CABF Baseline Requirements)";
 318     } else if ([key isEqualToString:@"NameConstraints"]) {
 319         errstr = @"Certificate violates name constraints placed on issuing CA";
 320     } else if ([key isEqualToString:@"PolicyConstraints"]) {
 321         errstr = @"Certificate violates policy constraints placed on issuing CA";
 322     } else if ([key isEqualToString:@"CTRequired"]) {
 323         errstr = @"Certificate Transparency validation is required but missing";
 324     } else if ([key isEqualToString:@"ValidityPeriodMaximums"]) {
 325         errstr = @"Certificate exceeds maximum allowable validity period (normally 825 days)";
 326     } else if ([key isEqualToString:@"ServerAuthEKU"]) {
 327         errstr = @"The Extended Key Usage extension does not permit server authentication";
 328     } else if ([key isEqualToString:@"UnparseableExtension"]) {
 329         errstr = @"Unable to parse a standard extension (corrupt or invalid format detected)";
 330     }
 331
 332     if (errstr) {
 333         errstr = [NSString stringWithFormat:@"%@ [%@]", errstr, key];
 334     } else {
 335         errstr = [NSString stringWithFormat:@"[%@]", key];
 336     }
 337     return errstr;
 338 }
 339
 340 void printErrorDetails(SecTrustRef trust)
 341 {
 342     CFDictionaryRef result = SecTrustCopyResult(trust);
 343     CFArrayRef properties = SecTrustCopyProperties(trust);
 344     NSArray *props = (__bridge NSArray *)properties;
 345     NSArray *details = [(__bridge NSDictionary *)result objectForKey:@"TrustResultDetails"];
 346     if (!props || !details) {
 347         if (result) { CFRelease(result); }
 348         if (properties) { CFRelease(properties); }
 349         return;
 350     }
 351     // Preflight to see if there are any errors to display
 352     CFIndex errorCount = 0, chainLength = [details count];
 353     for (CFIndex chainIndex = 0; chainIndex < chainLength; chainIndex++) {
 354         NSDictionary *certDetails = (NSDictionary *)[details objectAtIndex:chainIndex];
 355         errorCount += [certDetails count];
 356     }
 357     if (!errorCount) {
 358         if (result) { CFRelease(result); }
 359         if (properties) { CFRelease(properties); }
 360         return;
 361     }
 362
 363     // Display per-certificate errors
 364     fprintf(stdout, "---\nCertificate errors\n");
 365     for (CFIndex chainIndex = 0; chainIndex < chainLength; chainIndex++) {
 366         NSDictionary *certProps = (NSDictionary *)[props objectAtIndex:chainIndex];
 367         NSString *certTitle = (NSString *)[certProps objectForKey:(__bridge NSString*)kSecPropertyTypeTitle];
 368         fprintf(stdout, " %ld: %s\n", (long)chainIndex, [certTitle UTF8String]);
 369         NSDictionary *certDetails = (NSDictionary *)[details objectAtIndex:chainIndex];
 370         NSEnumerator *keyEnumerator = [certDetails keyEnumerator];
 371         NSString *key;
 372         while ((key = (NSString*)[keyEnumerator nextObject])) {
 373             NSString *str = errorStringForKey(key);
 374             if (!str) { continue; }
 375             fprintf(stdout, ANSI_RED "    %s" ANSI_RESET "\n", [str UTF8String]);
 376         }
 377     }
 378     fflush(stdout);
 379
 380     CFRelease(result);
 381     CFRelease(properties);
 382 }
 383
 384 void printExtendedResults(SecTrustRef trust)
 385 {
 386     CFDictionaryRef trustResults = SecTrustCopyResult(trust);
 387     if (!trustResults) { return; }
 388     fprintf(stdout, "---\n");
 389
 390     NSDictionary *results = (__bridge NSDictionary *)trustResults;
 391     NSString *orgName = [results objectForKey:(NSString *)kSecTrustOrganizationName];
 392     CFBooleanRef isEV = (__bridge CFBooleanRef)[results objectForKey:(NSString *)kSecTrustExtendedValidation];
 393     if (isEV == kCFBooleanTrue) {
 394         fprintf(stdout, "Extended Validation (EV) confirmed for \"" ANSI_GREEN "%s" ANSI_RESET "\"\n", [orgName UTF8String]);
 395     } else {
 396         fprintf(stdout, "No extended validation result found\n");
 397     }
 398     CFBooleanRef isCT = (__bridge CFBooleanRef)[results objectForKey:(NSString *)kSecTrustCertificateTransparency];
 399     CFBooleanRef isCTW = (__bridge CFBooleanRef)[results objectForKey:(NSString *)kSecTrustCertificateTransparencyWhiteList];
 400     if (isCT == kCFBooleanTrue) {
 401         fprintf(stdout, "Certificate Transparency (CT) status: " ANSI_GREEN "verified" ANSI_RESET "\n");
 402     } else if (isCTW == kCFBooleanTrue) {
 403         fprintf(stdout, "Certificate Transparency requirement waived for approved EV certificate\n");
 404     } else {
 405         fprintf(stdout, "Certificate Transparency (CT) status: " ANSI_RED "not verified" ANSI_RESET "\n");
 406         fprintf(stdout, "Unable to find at least 2 signed certificate timestamps (SCTs) from approved logs\n");
 407     }
 408     fflush(stdout);
 409     CFRelease(trustResults);
 410 }
 411
 412 int evaluate_ssl(const char *urlstr, int verbose, SecTrustRef * CF_RETURNS_RETAINED trustRef)
 413 {
 414     @autoreleasepool {
 415         _verbose = verbose;
 416         if (trustRef) {
 417             *trustRef = NULL;
 418         }
 419         if (![CertDownloader isNetworkURL:urlstr]) {
 420             return 2;
 421         }
 422         CertDownloader *context = [[CertDownloader alloc] initWithURLString:urlstr];
 423         [context waitForDownloadToFinish];
 424         SecTrustRef trust = [context trustReference];
 425         if (trustRef && trust) {
 426             CFRetain(trust);
 427             *trustRef = trust;
 428         }
 429     }
 430     return 0;
 431 }
 432
 433 static bool isHex(unichar c)
 434 {
 435     return ((c >= 0x30 && c <= 0x39) || /* 0..9 */
 436             (c >= 0x41 && c <= 0x46) || /* A..F */
 437             (c >= 0x61 && c <= 0x66));  /* a..f */
 438 }
 439
 440 static bool isEOL(unichar c)
 441 {
 442     return (c == 0x0D || c == 0x0A);
 443 }
 444
 445 CF_RETURNS_RETAINED CFStringRef CopyCertificateTextRepresentation(SecCertificateRef certificate)
 446 {
 447     if (!certificate) {
 448         return NULL;
 449     }
 450     @autoreleasepool {
 451         NSData *certData = [[[SFCertificateData alloc] initWithCertificate:certificate] tabDelimitedTextData];
 452         NSString *certStr = [[NSString alloc] initWithData:certData encoding:NSUnicodeStringEncoding];
 453         NSMutableString *outStr = [NSMutableString stringWithCapacity:0];
 454         [outStr appendString:certStr];
 455
 456         // process the output for readability by changing tabs to spaces
 457         CFIndex index, count = [outStr length];
 458         for (index = 1; index < count; index++) {
 459             unichar c = [outStr characterAtIndex:index];
 460             unichar p = [outStr characterAtIndex:index-1];
 461             if (isEOL(p)) { // start of line
 462                 while (c == 0x09) { // convert tabs to spaces until non-tab found
 463                     [outStr replaceCharactersInRange:NSMakeRange(index, 1) withString:@" "];
 464                     c = [outStr characterAtIndex:++index];
 465                 }
 466             } else if (c == 0x09) { // tab found between label and value
 467                 if (p == 0x20) { // continue the run of spaces
 468                     [outStr replaceCharactersInRange:NSMakeRange(index, 1) withString:@" "];
 469                 } else { // insert colon delimiter and space
 470                     [outStr replaceCharactersInRange:NSMakeRange(index, 1) withString:@": "];
 471                     count++; // we inserted an extra character
 472                 }
 473             }
 474         }
 475         // remove spaces in hexadecimal data representations for compactness
 476         count = [outStr length];
 477         index = 0;
 478         while (++index < count) {
 479             unichar c = [outStr characterAtIndex:index];
 480             unichar p = [outStr characterAtIndex:index-1];
 481             // possible start of hex data run occurs after colon delimiter
 482             if (p == 0x3A && c == 0x20) {
 483                 CFIndex start = index;
 484                 CFIndex len = 0;
 485                 while ((start+len+3 < count)) {
 486                     // scan for repeating three-character pattern
 487                     unichar first = [outStr characterAtIndex:start+len+0];
 488                     if (first != 0x20) {
 489                         break;
 490                     }
 491                     unichar second = [outStr characterAtIndex:start+len+1];
 492                     unichar third = [outStr characterAtIndex:start+len+2];
 493                     unichar last = [outStr characterAtIndex:start+len+3];
 494                     if (isHex(second) && isHex(third)) {
 495                         len += 3;
 496                     } else if (isEOL(second) && isHex(third) && isHex(last)) {
 497                         len += 4; // pattern continues on next line
 498                     } else {
 499                         break;
 500                     }
 501                 }
 502                 if (len > 0) {
 503                     // skip over the first space after the colon, which we want to keep
 504                     for (CFIndex idx = start+1; idx < count && idx < start+len; idx++) {
 505                         c = [outStr characterAtIndex:idx];
 506                         if (c == 0x20 || isEOL(c)) {
 507                             [outStr deleteCharactersInRange:NSMakeRange(idx,1)];
 508                             count--; // we removed a character from the total length
 509                             len--; // our substring also has one less character
 510                         }
 511                     }
 512                 }
 513             }
 514         }
 515         return CFBridgingRetain(outStr);
 516     }
 517 }
 518