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