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