methods/gpgv.cc

   1 #include <config.h>
   2
   3 #include <apt-pkg/acquire-method.h>
   4 #include <apt-pkg/configuration.h>
   5 #include <apt-pkg/error.h>
   6 #include <apt-pkg/gpgv.h>
   7 #include <apt-pkg/strutl.h>
   8 #include <apt-pkg/fileutl.h>
   9 #include "aptmethod.h"
  10
  11 #include <ctype.h>
  12 #include <errno.h>
  13 #include <stddef.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <sys/wait.h>
  18 #include <unistd.h>
  19
  20 #include <array>
  21 #include <algorithm>
  22 #include <sstream>
  23 #include <iterator>
  24 #include <iostream>
  25 #include <string>
  26 #include <vector>
  27
  28 #include <apti18n.h>
  29
  30 using std::string;
  31 using std::vector;
  32
  33 #define GNUPGPREFIX "[GNUPG:]"
  34 #define GNUPGBADSIG "[GNUPG:] BADSIG"
  35 #define GNUPGERRSIG "[GNUPG:] ERRSIG"
  36 #define GNUPGNOPUBKEY "[GNUPG:] NO_PUBKEY"
  37 #define GNUPGVALIDSIG "[GNUPG:] VALIDSIG"
  38 #define GNUPGGOODSIG "[GNUPG:] GOODSIG"
  39 #define GNUPGEXPKEYSIG "[GNUPG:] EXPKEYSIG"
  40 #define GNUPGEXPSIG "[GNUPG:] EXPSIG"
  41 #define GNUPGREVKEYSIG "[GNUPG:] REVKEYSIG"
  42 #define GNUPGNODATA "[GNUPG:] NODATA"
  43
  44 struct Digest {
  45    enum class State {
  46       Untrusted,
  47       Weak,
  48       Trusted,
  49    } state;
  50    char name[32];
  51
  52    State getState() const {
  53       std::string optionUntrusted;
  54       std::string optionWeak;
  55       strprintf(optionUntrusted, "APT::Hashes::%s::Untrusted", name);
  56       strprintf(optionWeak, "APT::Hashes::%s::Weak", name);
  57       if (_config->FindB(optionUntrusted, state == State::Untrusted) == true)
  58          return State::Untrusted;
  59       if (_config->FindB(optionWeak, state == State::Weak) == true)
  60          return State::Weak;
  61
  62       return state;
  63    }
  64 };
  65
  66 static constexpr Digest Digests[] = {
  67    {Digest::State::Untrusted, "Invalid digest"},
  68    {Digest::State::Untrusted, "MD5"},
  69    {Digest::State::Weak, "SHA1"},
  70    {Digest::State::Weak, "RIPE-MD/160"},
  71    {Digest::State::Trusted, "Reserved digest"},
  72    {Digest::State::Trusted, "Reserved digest"},
  73    {Digest::State::Trusted, "Reserved digest"},
  74    {Digest::State::Trusted, "Reserved digest"},
  75    {Digest::State::Trusted, "SHA256"},
  76    {Digest::State::Trusted, "SHA384"},
  77    {Digest::State::Trusted, "SHA512"},
  78    {Digest::State::Trusted, "SHA224"},
  79 };
  80
  81 static Digest FindDigest(std::string const & Digest)
  82 {
  83    int id = atoi(Digest.c_str());
  84    if (id >= 0 && static_cast<unsigned>(id) < _count(Digests)) {
  85       return Digests[id];
  86    } else {
  87       return Digests[0];
  88    }
  89 }
  90
  91 struct Signer {
  92    std::string key;
  93    std::string note;
  94 };
  95 static bool IsTheSameKey(std::string const &validsig, std::string const &goodsig) {
  96    // VALIDSIG reports a keyid (40 = 24 + 16), GOODSIG is a longid (16) only
  97    return validsig.compare(24, 16, goodsig, strlen("GOODSIG "), 16) == 0;
  98 }
  99
 100 class GPGVMethod : public aptMethod
 101 {
 102    private:
 103    string VerifyGetSigners(const char *file, const char *outfile,
 104                                 std::string const &key,
 105                                 vector<string> &GoodSigners,
 106                                 vector<string> &BadSigners,
 107                                 vector<string> &WorthlessSigners,
 108                                 vector<Signer> &SoonWorthlessSigners,
 109                                 vector<string> &NoPubKeySigners);
 110    protected:
 111    virtual bool URIAcquire(std::string const &Message, FetchItem *Itm) APT_OVERRIDE;
 112    public:
 113    GPGVMethod() : aptMethod("gpgv","1.0",SingleInstance | SendConfig) {};
 114 };
 115
 116 string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
 117                                          std::string const &key,
 118                                          vector<string> &GoodSigners,
 119                                          vector<string> &BadSigners,
 120                                          vector<string> &WorthlessSigners,
 121                                          vector<Signer> &SoonWorthlessSigners,
 122                                          vector<string> &NoPubKeySigners)
 123 {
 124    bool const Debug = _config->FindB("Debug::Acquire::gpgv", false);
 125
 126    if (Debug == true)
 127       std::clog << "inside VerifyGetSigners" << std::endl;
 128
 129    int fd[2];
 130    bool const keyIsID = (key.empty() == false && key[0] != '/');
 131
 132    if (pipe(fd) < 0)
 133       return "Couldn't create pipe";
 134
 135    pid_t pid = fork();
 136    if (pid < 0)
 137       return string("Couldn't spawn new process") + strerror(errno);
 138    else if (pid == 0)
 139       ExecGPGV(outfile, file, 3, fd, (keyIsID ? "" : key));
 140    close(fd[1]);
 141
 142    FILE *pipein = fdopen(fd[0], "r");
 143
 144    // Loop over the output of apt-key (which really is gnupg), and check the signatures.
 145    std::vector<std::string> ValidSigners;
 146    std::vector<std::string> ErrSigners;
 147    size_t buffersize = 0;
 148    char *buffer = NULL;
 149    while (1)
 150    {
 151       if (getline(&buffer, &buffersize, pipein) == -1)
 152          break;
 153       if (Debug == true)
 154          std::clog << "Read: " << buffer << std::endl;
 155
 156       // Push the data into three separate vectors, which
 157       // we later concatenate.  They're kept separate so
 158       // if we improve the apt method communication stuff later
 159       // it will be better.
 160       if (strncmp(buffer, GNUPGBADSIG, sizeof(GNUPGBADSIG)-1) == 0)
 161       {
 162          if (Debug == true)
 163             std::clog << "Got BADSIG! " << std::endl;
 164          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 165       }
 166       else if (strncmp(buffer, GNUPGERRSIG, sizeof(GNUPGERRSIG)-1) == 0)
 167       {
 168          if (Debug == true)
 169             std::clog << "Got ERRSIG " << std::endl;
 170          ErrSigners.push_back(string(buffer, strlen(GNUPGPREFIX), strlen("ERRSIG ") + 16));
 171       }
 172       else if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0)
 173       {
 174          if (Debug == true)
 175             std::clog << "Got NO_PUBKEY " << std::endl;
 176          NoPubKeySigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 177          ErrSigners.erase(std::remove_if(ErrSigners.begin(), ErrSigners.end(), [&](std::string const &errsig) {
 178                   return errsig.compare(strlen("ERRSIG "), 16, buffer, strlen(GNUPGNOPUBKEY), 16) == 0;  }), ErrSigners.end());
 179       }
 180       else if (strncmp(buffer, GNUPGNODATA, sizeof(GNUPGBADSIG)-1) == 0)
 181       {
 182          if (Debug == true)
 183             std::clog << "Got NODATA! " << std::endl;
 184          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 185       }
 186       else if (strncmp(buffer, GNUPGEXPKEYSIG, sizeof(GNUPGEXPKEYSIG)-1) == 0)
 187       {
 188          if (Debug == true)
 189             std::clog << "Got EXPKEYSIG! " << std::endl;
 190          WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 191       }
 192       else if (strncmp(buffer, GNUPGEXPSIG, sizeof(GNUPGEXPSIG)-1) == 0)
 193       {
 194          if (Debug == true)
 195             std::clog << "Got EXPSIG!" << std::endl;
 196          WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 197       }
 198       else if (strncmp(buffer, GNUPGREVKEYSIG, sizeof(GNUPGREVKEYSIG)-1) == 0)
 199       {
 200          if (Debug == true)
 201             std::clog << "Got REVKEYSIG! " << std::endl;
 202          WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 203       }
 204       else if (strncmp(buffer, GNUPGGOODSIG, sizeof(GNUPGGOODSIG)-1) == 0)
 205       {
 206          char *sig = buffer + sizeof(GNUPGPREFIX);
 207          char *p = sig + sizeof("GOODSIG");
 208          while (*p && isxdigit(*p))
 209             p++;
 210          *p = 0;
 211          if (Debug == true)
 212             std::clog << "Got GOODSIG, key ID:" << sig << std::endl;
 213          GoodSigners.push_back(string(sig));
 214       }
 215       else if (strncmp(buffer, GNUPGVALIDSIG, sizeof(GNUPGVALIDSIG)-1) == 0)
 216       {
 217          char *sig = buffer + sizeof(GNUPGVALIDSIG);
 218          std::istringstream iss((string(sig)));
 219          vector<string> tokens{std::istream_iterator<string>{iss},
 220                                std::istream_iterator<string>{}};
 221          char *p = sig;
 222          while (*p && isxdigit(*p))
 223             p++;
 224          *p = 0;
 225          // Reject weak digest algorithms
 226          Digest digest = FindDigest(tokens[7]);
 227          switch (digest.getState()) {
 228          case Digest::State::Weak:
 229             // Treat them like an expired key: For that a message about expiry
 230             // is emitted, a VALIDSIG, but no GOODSIG.
 231             SoonWorthlessSigners.push_back({string(sig), digest.name});
 232             if (Debug == true)
 233                std::clog << "Got weak VALIDSIG, key ID: " << sig << std::endl;
 234             break;
 235          case Digest::State::Untrusted:
 236             // Treat them like an expired key: For that a message about expiry
 237             // is emitted, a VALIDSIG, but no GOODSIG.
 238             WorthlessSigners.push_back(string(sig));
 239             GoodSigners.erase(std::remove_if(GoodSigners.begin(), GoodSigners.end(), [&](std::string const &goodsig) {
 240                      return IsTheSameKey(string(sig), goodsig); }), GoodSigners.end());
 241             if (Debug == true)
 242                std::clog << "Got untrusted VALIDSIG, key ID: " << sig << std::endl;
 243             break;
 244
 245          case Digest::State::Trusted:
 246             if (Debug == true)
 247                std::clog << "Got trusted VALIDSIG, key ID: " << sig << std::endl;
 248             break;
 249          }
 250
 251          ValidSigners.push_back(string(sig));
 252       }
 253    }
 254    fclose(pipein);
 255    free(buffer);
 256    std::move(ErrSigners.begin(), ErrSigners.end(), std::back_inserter(WorthlessSigners));
 257
 258    // apt-key has a --keyid parameter, but this requires gpg, so we call it without it
 259    // and instead check after the fact which keyids where used for verification
 260    if (keyIsID == true)
 261    {
 262       if (Debug == true)
 263          std::clog << "GoodSigs needs to be limited to keyid " << key << std::endl;
 264       std::vector<std::string>::iterator const foundItr = std::find(ValidSigners.begin(), ValidSigners.end(), key);
 265       bool const found = (foundItr != ValidSigners.end());
 266       std::copy(GoodSigners.begin(), GoodSigners.end(), std::back_insert_iterator<std::vector<std::string> >(NoPubKeySigners));
 267       if (found)
 268       {
 269          // we look for GOODSIG here as well as an expired sig is a valid sig as well (but not a good one)
 270          std::string const goodlongkeyid = "GOODSIG " + key.substr(24, 16);
 271          bool const foundGood = std::find(GoodSigners.begin(), GoodSigners.end(), goodlongkeyid) != GoodSigners.end();
 272          if (Debug == true)
 273             std::clog << "Key " << key << " is valid sig, is " << goodlongkeyid << " also a good one? " << (foundGood ? "yes" : "no") << std::endl;
 274          GoodSigners.clear();
 275          if (foundGood)
 276          {
 277             GoodSigners.push_back(goodlongkeyid);
 278             NoPubKeySigners.erase(std::remove(NoPubKeySigners.begin(), NoPubKeySigners.end(), goodlongkeyid), NoPubKeySigners.end());
 279          }
 280       }
 281       else
 282          GoodSigners.clear();
 283    }
 284
 285    int status;
 286    waitpid(pid, &status, 0);
 287    if (Debug == true)
 288    {
 289       ioprintf(std::clog, "gpgv exited with status %i\n", WEXITSTATUS(status));
 290    }
 291
 292    if (Debug)
 293    {
 294       std::cerr << "Summary:" << std::endl << "  Good: ";
 295       std::copy(GoodSigners.begin(), GoodSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", "));
 296       std::cerr << std::endl << "  Bad: ";
 297       std::copy(BadSigners.begin(), BadSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", "));
 298       std::cerr << std::endl << "  Worthless: ";
 299       std::copy(WorthlessSigners.begin(), WorthlessSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", "));
 300       std::cerr << std::endl << "  SoonWorthless: ";
 301       std::for_each(SoonWorthlessSigners.begin(), SoonWorthlessSigners.end(), [](Signer const &sig) { std::cerr << sig.key << ", "; });
 302       std::cerr << std::endl << "  NoPubKey: ";
 303       std::copy(NoPubKeySigners.begin(), NoPubKeySigners.end(), std::ostream_iterator<std::string>(std::cerr, ", "));
 304       std::cerr << std::endl;
 305    }
 306
 307    if (WEXITSTATUS(status) == 0)
 308    {
 309       if (keyIsID)
 310       {
 311          // gpgv will report success, but we want to enforce a certain keyring
 312          // so if we haven't found the key the valid we found is in fact invalid
 313          if (GoodSigners.empty())
 314             return _("At least one invalid signature was encountered.");
 315       }
 316       else
 317       {
 318          if (GoodSigners.empty())
 319             return _("Internal error: Good signature, but could not determine key fingerprint?!");
 320       }
 321       return "";
 322    }
 323    else if (WEXITSTATUS(status) == 1)
 324       return _("At least one invalid signature was encountered.");
 325    else if (WEXITSTATUS(status) == 111)
 326       return _("Could not execute 'apt-key' to verify signature (is gnupg installed?)");
 327    else if (WEXITSTATUS(status) == 112)
 328    {
 329       // acquire system checks for "NODATA" to generate GPG errors (the others are only warnings)
 330       std::string errmsg;
 331       //TRANSLATORS: %s is a single techy word like 'NODATA'
 332       strprintf(errmsg, _("Clearsigned file isn't valid, got '%s' (does the network require authentication?)"), "NODATA");
 333       return errmsg;
 334    }
 335    else
 336       return _("Unknown error executing apt-key");
 337 }
 338
 339 bool GPGVMethod::URIAcquire(std::string const &Message, FetchItem *Itm)
 340 {
 341    URI const Get = Itm->Uri;
 342    string const Path = Get.Host + Get.Path; // To account for relative paths
 343    std::string const key = LookupTag(Message, "Signed-By");
 344    vector<string> GoodSigners;
 345    vector<string> BadSigners;
 346    // a worthless signature is a expired or revoked one
 347    vector<string> WorthlessSigners;
 348    vector<Signer> SoonWorthlessSigners;
 349    vector<string> NoPubKeySigners;
 350
 351    FetchResult Res;
 352    Res.Filename = Itm->DestFile;
 353    URIStart(Res);
 354
 355    // Run apt-key on file, extract contents and get the key ID of the signer
 356    string msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(), key,
 357                                  GoodSigners, BadSigners, WorthlessSigners,
 358                                  SoonWorthlessSigners, NoPubKeySigners);
 359
 360    // Check if all good signers are soon worthless and warn in that case
 361    if (std::all_of(GoodSigners.begin(), GoodSigners.end(), [&](std::string const &good) {
 362             return std::any_of(SoonWorthlessSigners.begin(), SoonWorthlessSigners.end(), [&](Signer const &weak) {
 363                   return IsTheSameKey(weak.key, good);
 364                   });
 365             }))
 366    {
 367       for (auto const & Signer : SoonWorthlessSigners)
 368          // TRANSLATORS: The second %s is the reason and is untranslated for repository owners.
 369          Warning(_("Signature by key %s uses weak digest algorithm (%s)"), Signer.key.c_str(), Signer.note.c_str());
 370    }
 371
 372    if (GoodSigners.empty() || !BadSigners.empty() || !NoPubKeySigners.empty())
 373    {
 374       string errmsg;
 375       // In this case, something bad probably happened, so we just go
 376       // with what the other method gave us for an error message.
 377       if (BadSigners.empty() && WorthlessSigners.empty() && NoPubKeySigners.empty())
 378          errmsg = msg;
 379       else
 380       {
 381          if (!BadSigners.empty())
 382          {
 383             errmsg += _("The following signatures were invalid:\n");
 384             for (vector<string>::iterator I = BadSigners.begin();
 385                  I != BadSigners.end(); ++I)
 386                errmsg += (*I + "\n");
 387          }
 388          if (!WorthlessSigners.empty())
 389          {
 390             errmsg += _("The following signatures were invalid:\n");
 391             for (vector<string>::iterator I = WorthlessSigners.begin();
 392                  I != WorthlessSigners.end(); ++I)
 393                errmsg += (*I + "\n");
 394          }
 395          if (!NoPubKeySigners.empty())
 396          {
 397              errmsg += _("The following signatures couldn't be verified because the public key is not available:\n");
 398             for (vector<string>::iterator I = NoPubKeySigners.begin();
 399                  I != NoPubKeySigners.end(); ++I)
 400                errmsg += (*I + "\n");
 401          }
 402       }
 403       // this is only fatal if we have no good sigs or if we have at
 404       // least one bad signature. good signatures and NoPubKey signatures
 405       // happen easily when a file is signed with multiple signatures
 406       if(GoodSigners.empty() or !BadSigners.empty())
 407          return _error->Error("%s", errmsg.c_str());
 408    }
 409
 410    // Just pass the raw output up, because passing it as a real data
 411    // structure is too difficult with the method stuff.  We keep it
 412    // as three separate vectors for future extensibility.
 413    Res.GPGVOutput = GoodSigners;
 414    Res.GPGVOutput.insert(Res.GPGVOutput.end(),BadSigners.begin(),BadSigners.end());
 415    Res.GPGVOutput.insert(Res.GPGVOutput.end(),NoPubKeySigners.begin(),NoPubKeySigners.end());
 416    URIDone(Res);
 417
 418    if (_config->FindB("Debug::Acquire::gpgv", false))
 419    {
 420       std::clog << "apt-key succeeded\n";
 421    }
 422
 423    return true;
 424 }
 425
 426
 427 int main()
 428 {
 429    setlocale(LC_ALL, "");
 430
 431    GPGVMethod Mth;
 432
 433    return Mth.Run();
 434 }