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 static void PushEntryWithKeyID(std::vector<std::string> &Signers, char * const buffer, bool const Debug)
 116 {
 117    char * const msg = buffer + sizeof(GNUPGPREFIX);
 118    char *p = msg;
 119    // skip the message
 120    while (*p && !isspace(*p))
 121       ++p;
 122    // skip the seperator whitespace
 123    ++p;
 124    // skip the hexdigit fingerprint
 125    while (*p && isxdigit(*p))
 126       ++p;
 127    // cut the rest from the message
 128    *p = '\0';
 129    if (Debug == true)
 130       std::clog << "Got " << msg << " !" << std::endl;
 131    Signers.push_back(msg);
 132 }
 133 static void PushEntryWithUID(std::vector<std::string> &Signers, char * const buffer, bool const Debug)
 134 {
 135    std::string msg = buffer + sizeof(GNUPGPREFIX);
 136    auto const nuke = msg.find_last_not_of("\n\t\r");
 137    if (nuke != std::string::npos)
 138       msg.erase(nuke + 1);
 139    if (Debug == true)
 140       std::clog << "Got " << msg << " !" << std::endl;
 141    Signers.push_back(msg);
 142 }
 143 string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
 144                                          std::string const &key,
 145                                          vector<string> &GoodSigners,
 146                                          vector<string> &BadSigners,
 147                                          vector<string> &WorthlessSigners,
 148                                          vector<Signer> &SoonWorthlessSigners,
 149                                          vector<string> &NoPubKeySigners)
 150 {
 151    bool const Debug = _config->FindB("Debug::Acquire::gpgv", false);
 152
 153    if (Debug == true)
 154       std::clog << "inside VerifyGetSigners" << std::endl;
 155
 156    int fd[2];
 157    bool const keyIsID = (key.empty() == false && key[0] != '/');
 158
 159    if (pipe(fd) < 0)
 160       return "Couldn't create pipe";
 161
 162    pid_t pid = fork();
 163    if (pid < 0)
 164       return string("Couldn't spawn new process") + strerror(errno);
 165    else if (pid == 0)
 166       ExecGPGV(outfile, file, 3, fd, (keyIsID ? "" : key));
 167    close(fd[1]);
 168
 169    FILE *pipein = fdopen(fd[0], "r");
 170
 171    // Loop over the output of apt-key (which really is gnupg), and check the signatures.
 172    std::vector<std::string> ValidSigners;
 173    std::vector<std::string> ErrSigners;
 174    size_t buffersize = 0;
 175    char *buffer = NULL;
 176    while (1)
 177    {
 178       if (getline(&buffer, &buffersize, pipein) == -1)
 179          break;
 180       if (Debug == true)
 181          std::clog << "Read: " << buffer << std::endl;
 182
 183       // Push the data into three separate vectors, which
 184       // we later concatenate.  They're kept separate so
 185       // if we improve the apt method communication stuff later
 186       // it will be better.
 187       if (strncmp(buffer, GNUPGBADSIG, sizeof(GNUPGBADSIG)-1) == 0)
 188          PushEntryWithUID(BadSigners, buffer, Debug);
 189       else if (strncmp(buffer, GNUPGERRSIG, sizeof(GNUPGERRSIG)-1) == 0)
 190          PushEntryWithKeyID(ErrSigners, buffer, Debug);
 191       else if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0)
 192       {
 193          PushEntryWithKeyID(NoPubKeySigners, buffer, Debug);
 194          ErrSigners.erase(std::remove_if(ErrSigners.begin(), ErrSigners.end(), [&](std::string const &errsig) {
 195                   return errsig.compare(strlen("ERRSIG "), 16, buffer, sizeof(GNUPGNOPUBKEY), 16) == 0;  }), ErrSigners.end());
 196       }
 197       else if (strncmp(buffer, GNUPGNODATA, sizeof(GNUPGBADSIG)-1) == 0)
 198          PushEntryWithUID(BadSigners, buffer, Debug);
 199       else if (strncmp(buffer, GNUPGEXPKEYSIG, sizeof(GNUPGEXPKEYSIG)-1) == 0)
 200          PushEntryWithUID(WorthlessSigners, buffer, Debug);
 201       else if (strncmp(buffer, GNUPGEXPSIG, sizeof(GNUPGEXPSIG)-1) == 0)
 202          PushEntryWithUID(WorthlessSigners, buffer, Debug);
 203       else if (strncmp(buffer, GNUPGREVKEYSIG, sizeof(GNUPGREVKEYSIG)-1) == 0)
 204          PushEntryWithUID(WorthlessSigners, buffer, Debug);
 205       else if (strncmp(buffer, GNUPGGOODSIG, sizeof(GNUPGGOODSIG)-1) == 0)
 206          PushEntryWithKeyID(GoodSigners, buffer, Debug);
 207       else if (strncmp(buffer, GNUPGVALIDSIG, sizeof(GNUPGVALIDSIG)-1) == 0)
 208       {
 209          std::istringstream iss(buffer + sizeof(GNUPGVALIDSIG));
 210          vector<string> tokens{std::istream_iterator<string>{iss},
 211                                std::istream_iterator<string>{}};
 212          auto const sig = tokens[0];
 213          // Reject weak digest algorithms
 214          Digest digest = FindDigest(tokens[7]);
 215          switch (digest.getState()) {
 216          case Digest::State::Weak:
 217             // Treat them like an expired key: For that a message about expiry
 218             // is emitted, a VALIDSIG, but no GOODSIG.
 219             SoonWorthlessSigners.push_back({sig, digest.name});
 220             if (Debug == true)
 221                std::clog << "Got weak VALIDSIG, key ID: " << sig << std::endl;
 222             break;
 223          case Digest::State::Untrusted:
 224             // Treat them like an expired key: For that a message about expiry
 225             // is emitted, a VALIDSIG, but no GOODSIG.
 226             WorthlessSigners.push_back(sig);
 227             GoodSigners.erase(std::remove_if(GoodSigners.begin(), GoodSigners.end(), [&](std::string const &goodsig) {
 228                      return IsTheSameKey(sig, goodsig); }), GoodSigners.end());
 229             if (Debug == true)
 230                std::clog << "Got untrusted VALIDSIG, key ID: " << sig << std::endl;
 231             break;
 232
 233          case Digest::State::Trusted:
 234             if (Debug == true)
 235                std::clog << "Got trusted VALIDSIG, key ID: " << sig << std::endl;
 236             break;
 237          }
 238
 239          ValidSigners.push_back(sig);
 240       }
 241    }
 242    fclose(pipein);
 243    free(buffer);
 244    std::move(ErrSigners.begin(), ErrSigners.end(), std::back_inserter(WorthlessSigners));
 245
 246    // apt-key has a --keyid parameter, but this requires gpg, so we call it without it
 247    // and instead check after the fact which keyids where used for verification
 248    if (keyIsID == true)
 249    {
 250       if (Debug == true)
 251          std::clog << "GoodSigs needs to be limited to keyid " << key << std::endl;
 252       bool foundGood = false;
 253       for (auto const &k: VectorizeString(key, ','))
 254       {
 255          if (std::find(ValidSigners.begin(), ValidSigners.end(), k) == ValidSigners.end())
 256             continue;
 257          // we look for GOODSIG here as well as an expired sig is a valid sig as well (but not a good one)
 258          std::string const goodlongkeyid = "GOODSIG " + k.substr(24, 16);
 259          foundGood = std::find(GoodSigners.begin(), GoodSigners.end(), goodlongkeyid) != GoodSigners.end();
 260          if (Debug == true)
 261             std::clog << "Key " << k << " is valid sig, is " << goodlongkeyid << " also a good one? " << (foundGood ? "yes" : "no") << std::endl;
 262          if (foundGood == false)
 263             continue;
 264          std::copy(GoodSigners.begin(), GoodSigners.end(), std::back_insert_iterator<std::vector<std::string> >(NoPubKeySigners));
 265          GoodSigners.clear();
 266          GoodSigners.push_back(goodlongkeyid);
 267          NoPubKeySigners.erase(std::remove(NoPubKeySigners.begin(), NoPubKeySigners.end(), goodlongkeyid), NoPubKeySigners.end());
 268          break;
 269       }
 270       if (foundGood == false)
 271       {
 272          std::copy(GoodSigners.begin(), GoodSigners.end(), std::back_insert_iterator<std::vector<std::string> >(NoPubKeySigners));
 273          GoodSigners.clear();
 274       }
 275    }
 276
 277    int status;
 278    waitpid(pid, &status, 0);
 279    if (Debug == true)
 280    {
 281       ioprintf(std::clog, "gpgv exited with status %i\n", WEXITSTATUS(status));
 282    }
 283
 284    if (Debug)
 285    {
 286       std::cerr << "Summary:" << std::endl << "  Good: ";
 287       std::copy(GoodSigners.begin(), GoodSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", "));
 288       std::cerr << std::endl << "  Bad: ";
 289       std::copy(BadSigners.begin(), BadSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", "));
 290       std::cerr << std::endl << "  Worthless: ";
 291       std::copy(WorthlessSigners.begin(), WorthlessSigners.end(), std::ostream_iterator<std::string>(std::cerr, ", "));
 292       std::cerr << std::endl << "  SoonWorthless: ";
 293       std::for_each(SoonWorthlessSigners.begin(), SoonWorthlessSigners.end(), [](Signer const &sig) { std::cerr << sig.key << ", "; });
 294       std::cerr << std::endl << "  NoPubKey: ";
 295       std::copy(NoPubKeySigners.begin(), NoPubKeySigners.end(), std::ostream_iterator<std::string>(std::cerr, ", "));
 296       std::cerr << std::endl;
 297    }
 298
 299    if (WEXITSTATUS(status) == 0)
 300    {
 301       if (keyIsID)
 302       {
 303          // gpgv will report success, but we want to enforce a certain keyring
 304          // so if we haven't found the key the valid we found is in fact invalid
 305          if (GoodSigners.empty())
 306             return _("At least one invalid signature was encountered.");
 307       }
 308       else
 309       {
 310          if (GoodSigners.empty())
 311             return _("Internal error: Good signature, but could not determine key fingerprint?!");
 312       }
 313       return "";
 314    }
 315    else if (WEXITSTATUS(status) == 1)
 316       return _("At least one invalid signature was encountered.");
 317    else if (WEXITSTATUS(status) == 111)
 318       return _("Could not execute 'apt-key' to verify signature (is gnupg installed?)");
 319    else if (WEXITSTATUS(status) == 112)
 320    {
 321       // acquire system checks for "NODATA" to generate GPG errors (the others are only warnings)
 322       std::string errmsg;
 323       //TRANSLATORS: %s is a single techy word like 'NODATA'
 324       strprintf(errmsg, _("Clearsigned file isn't valid, got '%s' (does the network require authentication?)"), "NODATA");
 325       return errmsg;
 326    }
 327    else
 328       return _("Unknown error executing apt-key");
 329 }
 330
 331 bool GPGVMethod::URIAcquire(std::string const &Message, FetchItem *Itm)
 332 {
 333    URI const Get = Itm->Uri;
 334    string const Path = Get.Host + Get.Path; // To account for relative paths
 335    std::string const key = LookupTag(Message, "Signed-By");
 336    vector<string> GoodSigners;
 337    vector<string> BadSigners;
 338    // a worthless signature is a expired or revoked one
 339    vector<string> WorthlessSigners;
 340    vector<Signer> SoonWorthlessSigners;
 341    vector<string> NoPubKeySigners;
 342
 343    FetchResult Res;
 344    Res.Filename = Itm->DestFile;
 345    URIStart(Res);
 346
 347    // Run apt-key on file, extract contents and get the key ID of the signer
 348    string msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(), key,
 349                                  GoodSigners, BadSigners, WorthlessSigners,
 350                                  SoonWorthlessSigners, NoPubKeySigners);
 351
 352    // Check if all good signers are soon worthless and warn in that case
 353    if (std::all_of(GoodSigners.begin(), GoodSigners.end(), [&](std::string const &good) {
 354             return std::any_of(SoonWorthlessSigners.begin(), SoonWorthlessSigners.end(), [&](Signer const &weak) {
 355                   return IsTheSameKey(weak.key, good);
 356                   });
 357             }))
 358    {
 359       for (auto const & Signer : SoonWorthlessSigners)
 360          // TRANSLATORS: The second %s is the reason and is untranslated for repository owners.
 361          Warning(_("Signature by key %s uses weak digest algorithm (%s)"), Signer.key.c_str(), Signer.note.c_str());
 362    }
 363
 364    if (GoodSigners.empty() || !BadSigners.empty() || !NoPubKeySigners.empty())
 365    {
 366       string errmsg;
 367       // In this case, something bad probably happened, so we just go
 368       // with what the other method gave us for an error message.
 369       if (BadSigners.empty() && WorthlessSigners.empty() && NoPubKeySigners.empty())
 370          errmsg = msg;
 371       else
 372       {
 373          if (!BadSigners.empty())
 374          {
 375             errmsg += _("The following signatures were invalid:\n");
 376             for (vector<string>::iterator I = BadSigners.begin();
 377                  I != BadSigners.end(); ++I)
 378                errmsg += (*I + "\n");
 379          }
 380          if (!WorthlessSigners.empty())
 381          {
 382             errmsg += _("The following signatures were invalid:\n");
 383             for (vector<string>::iterator I = WorthlessSigners.begin();
 384                  I != WorthlessSigners.end(); ++I)
 385                errmsg += (*I + "\n");
 386          }
 387          if (!NoPubKeySigners.empty())
 388          {
 389              errmsg += _("The following signatures couldn't be verified because the public key is not available:\n");
 390             for (vector<string>::iterator I = NoPubKeySigners.begin();
 391                  I != NoPubKeySigners.end(); ++I)
 392                errmsg += (*I + "\n");
 393          }
 394       }
 395       // this is only fatal if we have no good sigs or if we have at
 396       // least one bad signature. good signatures and NoPubKey signatures
 397       // happen easily when a file is signed with multiple signatures
 398       if(GoodSigners.empty() or !BadSigners.empty())
 399          return _error->Error("%s", errmsg.c_str());
 400    }
 401
 402    // Just pass the raw output up, because passing it as a real data
 403    // structure is too difficult with the method stuff.  We keep it
 404    // as three separate vectors for future extensibility.
 405    Res.GPGVOutput = GoodSigners;
 406    std::move(BadSigners.begin(), BadSigners.end(), std::back_inserter(Res.GPGVOutput));
 407    std::move(NoPubKeySigners.begin(), NoPubKeySigners.end(), std::back_inserter(Res.GPGVOutput));
 408    URIDone(Res);
 409
 410    if (_config->FindB("Debug::Acquire::gpgv", false))
 411    {
 412       std::clog << "apt-key succeeded\n";
 413    }
 414
 415    return true;
 416 }
 417
 418
 419 int main()
 420 {
 421    setlocale(LC_ALL, "");
 422
 423    GPGVMethod Mth;
 424
 425    return Mth.Run();
 426 }