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          for(unsigned int j=0;Args[j] != NULL; j++)
 104             std::cerr << " " << Args[j];
 105          std::cerr << std::endl;
 106       }
 107       int nullfd = open("/dev/null", O_RDONLY);
 108       close(fd[0]);
 109       // Redirect output to /dev/null; we read from the status fd
 110       dup2(nullfd, STDOUT_FILENO);
 111       dup2(nullfd, STDERR_FILENO);
 112       // Redirect the pipe to the status fd (3)
 113       dup2(fd[1], 3);
 114
 115       putenv("LANG=");
 116       putenv("LC_ALL=");
 117       putenv("LC_MESSAGES=");
 118       execvp(gpgvpath.c_str(), (char **)Args);
 119
 120       exit(111);
 121    }
 122    close(fd[1]);
 123
 124    pipein = fdopen(fd[0], "r");
 125
 126    // Loop over the output of gpgv, and check the signatures.
 127    size_t buffersize = 64;
 128    char *buffer = (char *) malloc(buffersize);
 129    size_t bufferoff = 0;
 130    while (1)
 131    {
 132       int c;
 133
 134       // Read a line.  Sigh.
 135       while ((c = getc(pipein)) != EOF && c != '\n')
 136       {
 137          if (bufferoff == buffersize)
 138             buffer = (char *) realloc(buffer, buffersize *= 2);
 139          *(buffer+bufferoff) = c;
 140          bufferoff++;
 141       }
 142       if (bufferoff == 0 && c == EOF)
 143          break;
 144       *(buffer+bufferoff) = '\0';
 145       bufferoff = 0;
 146       if (_config->FindB("Debug::Acquire::gpgv", false))
 147          std::cerr << "Read: " << buffer << std::endl;
 148
 149       // Push the data into three separate vectors, which
 150       // we later concatenate.  They're kept separate so
 151       // if we improve the apt method communication stuff later
 152       // it will be better.
 153       if (strncmp(buffer, GNUPGBADSIG, sizeof(GNUPGBADSIG)-1) == 0)
 154       {
 155          if (_config->FindB("Debug::Acquire::gpgv", false))
 156             std::cerr << "Got BADSIG! " << std::endl;
 157          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 158       }
 159
 160       if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0)
 161       {
 162          if (_config->FindB("Debug::Acquire::gpgv", false))
 163             std::cerr << "Got NO_PUBKEY " << std::endl;
 164          NoPubKeySigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 165       }
 166
 167       if (strncmp(buffer, GNUPGVALIDSIG, sizeof(GNUPGVALIDSIG)-1) == 0)
 168       {
 169          char *sig = buffer + sizeof(GNUPGPREFIX);
 170          char *p = sig + sizeof("VALIDSIG");
 171          while (*p && isxdigit(*p))
 172             p++;
 173          *p = 0;
 174          if (_config->FindB("Debug::Acquire::gpgv", false))
 175             std::cerr << "Got VALIDSIG, key ID:" << sig << std::endl;
 176          GoodSigners.push_back(string(sig));
 177       }
 178    }
 179    fclose(pipein);
 180
 181    waitpid(pid, &status, 0);
 182    if (_config->FindB("Debug::Acquire::gpgv", false))
 183    {
 184       std::cerr <<"gpgv exited\n";
 185    }
 186
 187    if (WEXITSTATUS(status) == 0)
 188    {
 189       if (GoodSigners.empty())
 190          return "Internal error: Good signature, but could not determine key fingerprint?!";
 191       return NULL;
 192    }
 193    else if (WEXITSTATUS(status) == 1)
 194    {
 195       return "At least one invalid signature was encountered.";
 196    }
 197    else if (WEXITSTATUS(status) == 111)
 198    {
 199       return (string("Could not execute ") + gpgvpath +
 200               string(" to verify signature (is gnupg installed?)")).c_str();
 201    }
 202    else
 203    {
 204       return "Unknown error executing gpgv";
 205    }
 206 }
 207
 208 bool GPGVMethod::Fetch(FetchItem *Itm)
 209 {
 210    URI Get = Itm->Uri;
 211    string Path = Get.Host + Get.Path; // To account for relative paths
 212    string keyID;
 213    vector<string> GoodSigners;
 214    vector<string> BadSigners;
 215    vector<string> NoPubKeySigners;
 216
 217    FetchResult Res;
 218    Res.Filename = Itm->DestFile;
 219    URIStart(Res);
 220
 221    // Run gpgv on file, extract contents and get the key ID of the signer
 222    const char *msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(),
 223                                       GoodSigners, BadSigners, NoPubKeySigners);
 224    if (GoodSigners.empty() || !BadSigners.empty() || !NoPubKeySigners.empty())
 225    {
 226       string errmsg;
 227       // In this case, something bad probably happened, so we just go
 228       // with what the other method gave us for an error message.
 229       if (BadSigners.empty() && NoPubKeySigners.empty())
 230          errmsg = msg;
 231       else
 232       {
 233          if (!BadSigners.empty())
 234          {
 235             errmsg += "The following signatures were invalid:\n";
 236             for (vector<string>::iterator I = BadSigners.begin();
 237                  I != BadSigners.end(); I++)
 238                errmsg += (*I + "\n");
 239          }
 240          if (!NoPubKeySigners.empty())
 241          {
 242              errmsg += "The following signatures couldn't be verified because the public key is not available:\n";
 243             for (vector<string>::iterator I = NoPubKeySigners.begin();
 244                  I != NoPubKeySigners.end(); I++)
 245                errmsg += (*I + "\n");
 246          }
 247       }
 248       return _error->Error(errmsg.c_str());
 249    }
 250
 251    // Transfer the modification times
 252    struct stat Buf;
 253    if (stat(Path.c_str(),&Buf) != 0)
 254       return _error->Errno("stat","Failed to stat %s", Path.c_str());
 255
 256    struct utimbuf TimeBuf;
 257    TimeBuf.actime = Buf.st_atime;
 258    TimeBuf.modtime = Buf.st_mtime;
 259    if (utime(Itm->DestFile.c_str(),&TimeBuf) != 0)
 260       return _error->Errno("utime","Failed to set modification time");
 261
 262    if (stat(Itm->DestFile.c_str(),&Buf) != 0)
 263       return _error->Errno("stat","Failed to stat");
 264
 265    // Return a Done response
 266    Res.LastModified = Buf.st_mtime;
 267    Res.Size = Buf.st_size;
 268    // Just pass the raw output up, because passing it as a real data
 269    // structure is too difficult with the method stuff.  We keep it
 270    // as three separate vectors for future extensibility.
 271    Res.GPGVOutput = GoodSigners;
 272    Res.GPGVOutput.insert(Res.GPGVOutput.end(),BadSigners.begin(),BadSigners.end());
 273    Res.GPGVOutput.insert(Res.GPGVOutput.end(),NoPubKeySigners.begin(),NoPubKeySigners.end());
 274    URIDone(Res);
 275
 276    if (_config->FindB("Debug::Acquire::gpgv", false))
 277    {
 278       std::cerr <<"gpgv suceeded\n";
 279    }
 280
 281    return true;
 282 }
 283
 284
 285 int main()
 286 {
 287    GPGVMethod Mth;
 288
 289    return Mth.Run();
 290 }