methods/gpgv.cc

   1 #include <apt-pkg/error.h>
   2 #include <apt-pkg/acquire-method.h>
   3 #include <apt-pkg/strutl.h>
   4 #include <apti18n.h>
   5
   6 #include <sys/stat.h>
   7 #include <unistd.h>
   8 #include <utime.h>
   9 #include <stdio.h>
  10 #include <fcntl.h>
  11 #include <errno.h>
  12 #include <sys/wait.h>
  13 #include <iostream>
  14 #include <sstream>
  15
  16 #define GNUPGPREFIX "[GNUPG:]"
  17 #define GNUPGBADSIG "[GNUPG:] BADSIG"
  18 #define GNUPGNOPUBKEY "[GNUPG:] NO_PUBKEY"
  19 #define GNUPGVALIDSIG "[GNUPG:] VALIDSIG"
  20 #define GNUPGNODATA "[GNUPG:] NODATA"
  21
  22 class GPGVMethod : public pkgAcqMethod
  23 {
  24    private:
  25    string VerifyGetSigners(const char *file, const char *outfile,
  26                                 vector<string> &GoodSigners, vector<string> &BadSigners,
  27                                 vector<string> &NoPubKeySigners);
  28
  29    protected:
  30    virtual bool Fetch(FetchItem *Itm);
  31
  32    public:
  33
  34    GPGVMethod() : pkgAcqMethod("1.0",SingleInstance | SendConfig) {};
  35 };
  36
  37 string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
  38                                          vector<string> &GoodSigners,
  39                                          vector<string> &BadSigners,
  40                                          vector<string> &NoPubKeySigners)
  41 {
  42    // setup a (empty) stringstream for formating the return value
  43    std::stringstream ret;
  44    ret.str("");
  45
  46    if (_config->FindB("Debug::Acquire::gpgv", false))
  47    {
  48       std::cerr << "inside VerifyGetSigners" << std::endl;
  49    }
  50    pid_t pid;
  51    int fd[2];
  52    FILE *pipein;
  53    int status;
  54    struct stat buff;
  55    string gpgvpath = _config->Find("Dir::Bin::gpg", "/usr/bin/gpgv");
  56    string pubringpath = _config->Find("APT::GPGV::TrustedKeyring", "/etc/apt/trusted.gpg");
  57    if (_config->FindB("Debug::Acquire::gpgv", false))
  58    {
  59       std::cerr << "gpgv path: " << gpgvpath << std::endl;
  60       std::cerr << "Keyring path: " << pubringpath << std::endl;
  61    }
  62
  63    if (stat(pubringpath.c_str(), &buff) != 0)
  64    {
  65       ioprintf(ret, _("Couldn't access keyring: '%s'"), strerror(errno));
  66       return ret.str();
  67    }
  68    if (pipe(fd) < 0)
  69    {
  70       return "Couldn't create pipe";
  71    }
  72
  73    pid = fork();
  74    if (pid < 0)
  75    {
  76       return string("Couldn't spawn new process") + strerror(errno);
  77    }
  78    else if (pid == 0)
  79    {
  80       const char *Args[400];
  81       unsigned int i = 0;
  82
  83       Args[i++] = gpgvpath.c_str();
  84       Args[i++] = "--status-fd";
  85       Args[i++] = "3";
  86       Args[i++] = "--keyring";
  87       Args[i++] = pubringpath.c_str();
  88
  89       Configuration::Item const *Opts;
  90       Opts = _config->Tree("Acquire::gpgv::Options");
  91       if (Opts != 0)
  92       {
  93          Opts = Opts->Child;
  94          for (; Opts != 0; Opts = Opts->Next)
  95          {
  96             if (Opts->Value.empty() == true)
  97                continue;
  98             Args[i++] = Opts->Value.c_str();
  99             if(i >= 395) {
 100                std::cerr << _("E: Argument list from Acquire::gpgv::Options too long. Exiting.") << std::endl;
 101                exit(111);
 102             }
 103          }
 104       }
 105       Args[i++] = file;
 106       Args[i++] = outfile;
 107       Args[i++] = NULL;
 108
 109       if (_config->FindB("Debug::Acquire::gpgv", false))
 110       {
 111          std::cerr << "Preparing to exec: " << gpgvpath;
 112          for(unsigned int j=0;Args[j] != NULL; j++)
 113             std::cerr << " " << Args[j];
 114          std::cerr << std::endl;
 115       }
 116       int nullfd = open("/dev/null", O_RDONLY);
 117       close(fd[0]);
 118       // Redirect output to /dev/null; we read from the status fd
 119       dup2(nullfd, STDOUT_FILENO);
 120       dup2(nullfd, STDERR_FILENO);
 121       // Redirect the pipe to the status fd (3)
 122       dup2(fd[1], 3);
 123
 124       putenv((char *)"LANG=");
 125       putenv((char *)"LC_ALL=");
 126       putenv((char *)"LC_MESSAGES=");
 127       execvp(gpgvpath.c_str(), (char **)Args);
 128
 129       exit(111);
 130    }
 131    close(fd[1]);
 132
 133    pipein = fdopen(fd[0], "r");
 134
 135    // Loop over the output of gpgv, and check the signatures.
 136    size_t buffersize = 64;
 137    char *buffer = (char *) malloc(buffersize);
 138    size_t bufferoff = 0;
 139    while (1)
 140    {
 141       int c;
 142
 143       // Read a line.  Sigh.
 144       while ((c = getc(pipein)) != EOF && c != '\n')
 145       {
 146          if (bufferoff == buffersize)
 147             buffer = (char *) realloc(buffer, buffersize *= 2);
 148          *(buffer+bufferoff) = c;
 149          bufferoff++;
 150       }
 151       if (bufferoff == 0 && c == EOF)
 152          break;
 153       *(buffer+bufferoff) = '\0';
 154       bufferoff = 0;
 155       if (_config->FindB("Debug::Acquire::gpgv", false))
 156          std::cerr << "Read: " << buffer << std::endl;
 157
 158       // Push the data into three separate vectors, which
 159       // we later concatenate.  They're kept separate so
 160       // if we improve the apt method communication stuff later
 161       // it will be better.
 162       if (strncmp(buffer, GNUPGBADSIG, sizeof(GNUPGBADSIG)-1) == 0)
 163       {
 164          if (_config->FindB("Debug::Acquire::gpgv", false))
 165             std::cerr << "Got BADSIG! " << std::endl;
 166          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 167       }
 168
 169       if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0)
 170       {
 171          if (_config->FindB("Debug::Acquire::gpgv", false))
 172             std::cerr << "Got NO_PUBKEY " << std::endl;
 173          NoPubKeySigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 174       }
 175       if (strncmp(buffer, GNUPGNODATA, sizeof(GNUPGBADSIG)-1) == 0)
 176       {
 177          if (_config->FindB("Debug::Acquire::gpgv", false))
 178             std::cerr << "Got NODATA! " << std::endl;
 179          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 180       }
 181       if (strncmp(buffer, GNUPGVALIDSIG, sizeof(GNUPGVALIDSIG)-1) == 0)
 182       {
 183          char *sig = buffer + sizeof(GNUPGPREFIX);
 184          char *p = sig + sizeof("VALIDSIG");
 185          while (*p && isxdigit(*p))
 186             p++;
 187          *p = 0;
 188          if (_config->FindB("Debug::Acquire::gpgv", false))
 189             std::cerr << "Got VALIDSIG, key ID:" << sig << std::endl;
 190          GoodSigners.push_back(string(sig));
 191       }
 192    }
 193    fclose(pipein);
 194
 195    waitpid(pid, &status, 0);
 196    if (_config->FindB("Debug::Acquire::gpgv", false))
 197    {
 198       std::cerr << "gpgv exited\n";
 199    }
 200
 201    if (WEXITSTATUS(status) == 0)
 202    {
 203       if (GoodSigners.empty())
 204          return _("Internal error: Good signature, but could not determine key fingerprint?!");
 205       return "";
 206    }
 207    else if (WEXITSTATUS(status) == 1)
 208    {
 209       return _("At least one invalid signature was encountered.");
 210    }
 211    else if (WEXITSTATUS(status) == 111)
 212    {
 213       ioprintf(ret, _("Could not execute '%s' to verify signature (is gnupg installed?)"), gpgvpath.c_str());
 214       return ret.str();
 215    }
 216    else
 217    {
 218       return _("Unknown error executing gpgv");
 219    }
 220 }
 221
 222 bool GPGVMethod::Fetch(FetchItem *Itm)
 223 {
 224    URI Get = Itm->Uri;
 225    string Path = Get.Host + Get.Path; // To account for relative paths
 226    string keyID;
 227    vector<string> GoodSigners;
 228    vector<string> BadSigners;
 229    vector<string> NoPubKeySigners;
 230
 231    FetchResult Res;
 232    Res.Filename = Itm->DestFile;
 233    URIStart(Res);
 234
 235    // Run gpgv on file, extract contents and get the key ID of the signer
 236    string msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(),
 237                               GoodSigners, BadSigners, NoPubKeySigners);
 238    if (GoodSigners.empty() || !BadSigners.empty() || !NoPubKeySigners.empty())
 239    {
 240       string errmsg;
 241       // In this case, something bad probably happened, so we just go
 242       // with what the other method gave us for an error message.
 243       if (BadSigners.empty() && NoPubKeySigners.empty())
 244          errmsg = msg;
 245       else
 246       {
 247          if (!BadSigners.empty())
 248          {
 249             errmsg += _("The following signatures were invalid:\n");
 250             for (vector<string>::iterator I = BadSigners.begin();
 251                  I != BadSigners.end(); I++)
 252                errmsg += (*I + "\n");
 253          }
 254          if (!NoPubKeySigners.empty())
 255          {
 256              errmsg += _("The following signatures couldn't be verified because the public key is not available:\n");
 257             for (vector<string>::iterator I = NoPubKeySigners.begin();
 258                  I != NoPubKeySigners.end(); I++)
 259                errmsg += (*I + "\n");
 260          }
 261       }
 262       // this is only fatal if we have no good sigs or if we have at
 263       // least one bad signature. good signatures and NoPubKey signatures
 264       // happen easily when a file is signed with multiple signatures
 265       if(GoodSigners.empty() or !BadSigners.empty())
 266          return _error->Error(errmsg.c_str());
 267    }
 268
 269    // Transfer the modification times
 270    struct stat Buf;
 271    if (stat(Path.c_str(),&Buf) != 0)
 272       return _error->Errno("stat",_("Failed to stat %s"), Path.c_str());
 273
 274    struct utimbuf TimeBuf;
 275    TimeBuf.actime = Buf.st_atime;
 276    TimeBuf.modtime = Buf.st_mtime;
 277    if (utime(Itm->DestFile.c_str(),&TimeBuf) != 0)
 278       return _error->Errno("utime",_("Failed to set modification time"));
 279
 280    if (stat(Itm->DestFile.c_str(),&Buf) != 0)
 281       return _error->Errno("stat",_("Failed to stat"));
 282
 283    // Return a Done response
 284    Res.LastModified = Buf.st_mtime;
 285    Res.Size = Buf.st_size;
 286    // Just pass the raw output up, because passing it as a real data
 287    // structure is too difficult with the method stuff.  We keep it
 288    // as three separate vectors for future extensibility.
 289    Res.GPGVOutput = GoodSigners;
 290    Res.GPGVOutput.insert(Res.GPGVOutput.end(),BadSigners.begin(),BadSigners.end());
 291    Res.GPGVOutput.insert(Res.GPGVOutput.end(),NoPubKeySigners.begin(),NoPubKeySigners.end());
 292    URIDone(Res);
 293
 294    if (_config->FindB("Debug::Acquire::gpgv", false))
 295    {
 296       std::cerr << "gpgv succeeded\n";
 297    }
 298
 299    return true;
 300 }
 301
 302
 303 int main()
 304 {
 305    setlocale(LC_ALL, "");
 306
 307    GPGVMethod Mth;
 308
 309    return Mth.Run();
 310 }