methods/gpgv.cc

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