methods/gpgv.cc

   1 extern "C" {
   2     #include <mach-o/nlist.h>
   3 }
   4
   5 #include <apt-pkg/error.h>
   6 #include <apt-pkg/acquire-method.h>
   7 #include <apt-pkg/strutl.h>
   8 #include <apti18n.h>
   9
  10 #include <sys/stat.h>
  11 #include <unistd.h>
  12 #include <utime.h>
  13 #include <stdio.h>
  14 #include <fcntl.h>
  15 #include <errno.h>
  16 #include <sys/wait.h>
  17 #include <iostream>
  18 #include <sstream>
  19
  20 #define GNUPGPREFIX "[GNUPG:]"
  21 #define GNUPGBADSIG "[GNUPG:] BADSIG"
  22 #define GNUPGNOPUBKEY "[GNUPG:] NO_PUBKEY"
  23 #define GNUPGVALIDSIG "[GNUPG:] VALIDSIG"
  24 #define GNUPGNODATA "[GNUPG:] NODATA"
  25
  26 class GPGVMethod : public pkgAcqMethod
  27 {
  28    private:
  29    string VerifyGetSigners(const char *file, const char *outfile,
  30                                 vector<string> &GoodSigners, vector<string> &BadSigners,
  31                                 vector<string> &NoPubKeySigners);
  32
  33    protected:
  34    virtual bool Fetch(FetchItem *Itm);
  35
  36    public:
  37
  38    GPGVMethod() : pkgAcqMethod("1.0",SingleInstance | SendConfig) {};
  39 };
  40
  41 string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
  42                                          vector<string> &GoodSigners,
  43                                          vector<string> &BadSigners,
  44                                          vector<string> &NoPubKeySigners)
  45 {
  46    // setup a (empty) stringstream for formating the return value
  47    std::stringstream ret;
  48    ret.str("");
  49
  50    if (_config->FindB("Debug::Acquire::gpgv", false))
  51    {
  52       std::cerr << "inside VerifyGetSigners" << std::endl;
  53    }
  54    pid_t pid;
  55    int fd[2];
  56    FILE *pipein;
  57    int status;
  58    struct stat buff;
  59    string gpgvpath = _config->Find("Dir::Bin::gpg", "/usr/bin/gpgv");
  60    string pubringpath = _config->Find("APT::GPGV::TrustedKeyring", "/etc/apt/trusted.gpg");
  61    if (_config->FindB("Debug::Acquire::gpgv", false))
  62    {
  63       std::cerr << "gpgv path: " << gpgvpath << std::endl;
  64       std::cerr << "Keyring path: " << pubringpath << std::endl;
  65    }
  66
  67    if (stat(pubringpath.c_str(), &buff) != 0)
  68    {
  69       ioprintf(ret, _("Couldn't access keyring: '%s'"), strerror(errno));
  70       return ret.str();
  71    }
  72    if (pipe(fd) < 0)
  73    {
  74       return "Couldn't create pipe";
  75    }
  76
  77    pid = fork();
  78    if (pid < 0)
  79    {
  80       return string("Couldn't spawn new process") + strerror(errno);
  81    }
  82    else if (pid == 0)
  83    {
  84       const char *Args[400];
  85       unsigned int i = 0;
  86
  87       Args[i++] = gpgvpath.c_str();
  88       Args[i++] = "--status-fd";
  89       Args[i++] = "3";
  90       Args[i++] = "--keyring";
  91       Args[i++] = pubringpath.c_str();
  92
  93       Configuration::Item const *Opts;
  94       Opts = _config->Tree("Acquire::gpgv::Options");
  95       if (Opts != 0)
  96       {
  97          Opts = Opts->Child;
  98          for (; Opts != 0; Opts = Opts->Next)
  99          {
 100             if (Opts->Value.empty() == true)
 101                continue;
 102             Args[i++] = Opts->Value.c_str();
 103             if(i >= 395) {
 104                std::cerr << _("E: Argument list from Acquire::gpgv::Options too long. Exiting.") << std::endl;
 105                exit(111);
 106             }
 107          }
 108       }
 109       Args[i++] = file;
 110       Args[i++] = outfile;
 111       Args[i++] = NULL;
 112
 113       if (_config->FindB("Debug::Acquire::gpgv", false))
 114       {
 115          std::cerr << "Preparing to exec: " << gpgvpath;
 116          for(unsigned int j=0;Args[j] != NULL; j++)
 117             std::cerr << " " << Args[j];
 118          std::cerr << std::endl;
 119       }
 120       int nullfd = open("/dev/null", O_RDONLY);
 121       close(fd[0]);
 122       // Redirect output to /dev/null; we read from the status fd
 123       dup2(nullfd, STDOUT_FILENO);
 124       dup2(nullfd, STDERR_FILENO);
 125       // Redirect the pipe to the status fd (3)
 126       dup2(fd[1], 3);
 127
 128       putenv("LANG=");
 129       putenv("LC_ALL=");
 130       putenv("LC_MESSAGES=");
 131       execvp(gpgvpath.c_str(), (char **)Args);
 132
 133       exit(111);
 134    }
 135    close(fd[1]);
 136
 137    pipein = fdopen(fd[0], "r");
 138
 139    // Loop over the output of gpgv, and check the signatures.
 140    size_t buffersize = 64;
 141    char *buffer = (char *) malloc(buffersize);
 142    size_t bufferoff = 0;
 143    while (1)
 144    {
 145       int c;
 146
 147       // Read a line.  Sigh.
 148       while ((c = getc(pipein)) != EOF && c != '\n')
 149       {
 150          if (bufferoff == buffersize)
 151             buffer = (char *) realloc(buffer, buffersize *= 2);
 152          *(buffer+bufferoff) = c;
 153          bufferoff++;
 154       }
 155       if (bufferoff == 0 && c == EOF)
 156          break;
 157       *(buffer+bufferoff) = '\0';
 158       bufferoff = 0;
 159       if (_config->FindB("Debug::Acquire::gpgv", false))
 160          std::cerr << "Read: " << buffer << std::endl;
 161
 162       // Push the data into three separate vectors, which
 163       // we later concatenate.  They're kept separate so
 164       // if we improve the apt method communication stuff later
 165       // it will be better.
 166       if (strncmp(buffer, GNUPGBADSIG, sizeof(GNUPGBADSIG)-1) == 0)
 167       {
 168          if (_config->FindB("Debug::Acquire::gpgv", false))
 169             std::cerr << "Got BADSIG! " << std::endl;
 170          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 171       }
 172
 173       if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0)
 174       {
 175          if (_config->FindB("Debug::Acquire::gpgv", false))
 176             std::cerr << "Got NO_PUBKEY " << std::endl;
 177          NoPubKeySigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 178       }
 179       if (strncmp(buffer, GNUPGNODATA, sizeof(GNUPGBADSIG)-1) == 0)
 180       {
 181          if (_config->FindB("Debug::Acquire::gpgv", false))
 182             std::cerr << "Got NODATA! " << std::endl;
 183          BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
 184       }
 185       if (strncmp(buffer, GNUPGVALIDSIG, sizeof(GNUPGVALIDSIG)-1) == 0)
 186       {
 187          char *sig = buffer + sizeof(GNUPGPREFIX);
 188          char *p = sig + sizeof("VALIDSIG");
 189          while (*p && isxdigit(*p))
 190             p++;
 191          *p = 0;
 192          if (_config->FindB("Debug::Acquire::gpgv", false))
 193             std::cerr << "Got VALIDSIG, key ID:" << sig << std::endl;
 194          GoodSigners.push_back(string(sig));
 195       }
 196    }
 197    fclose(pipein);
 198
 199    waitpid(pid, &status, 0);
 200    if (_config->FindB("Debug::Acquire::gpgv", false))
 201    {
 202       std::cerr << "gpgv exited\n";
 203    }
 204
 205    if (WEXITSTATUS(status) == 0)
 206    {
 207       if (GoodSigners.empty())
 208          return _("Internal error: Good signature, but could not determine key fingerprint?!");
 209       return "";
 210    }
 211    else if (WEXITSTATUS(status) == 1)
 212    {
 213       return _("At least one invalid signature was encountered.");
 214    }
 215    else if (WEXITSTATUS(status) == 111)
 216    {
 217       ioprintf(ret, _("Could not execute '%s' to verify signature (is gnupg installed?)"), gpgvpath.c_str());
 218       return ret.str();
 219    }
 220    else
 221    {
 222       return _("Unknown error executing gpgv");
 223    }
 224 }
 225
 226 bool GPGVMethod::Fetch(FetchItem *Itm)
 227 {
 228    URI Get = Itm->Uri;
 229    string Path = Get.Host + Get.Path; // To account for relative paths
 230    string keyID;
 231    vector<string> GoodSigners;
 232    vector<string> BadSigners;
 233    vector<string> NoPubKeySigners;
 234
 235    FetchResult Res;
 236    Res.Filename = Itm->DestFile;
 237    URIStart(Res);
 238
 239    // Run gpgv on file, extract contents and get the key ID of the signer
 240    string msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(),
 241                               GoodSigners, BadSigners, NoPubKeySigners);
 242    if (GoodSigners.empty() || !BadSigners.empty() || !NoPubKeySigners.empty())
 243    {
 244       string errmsg;
 245       // In this case, something bad probably happened, so we just go
 246       // with what the other method gave us for an error message.
 247       if (BadSigners.empty() && NoPubKeySigners.empty())
 248          errmsg = msg;
 249       else
 250       {
 251          if (!BadSigners.empty())
 252          {
 253             errmsg += _("The following signatures were invalid:\n");
 254             for (vector<string>::iterator I = BadSigners.begin();
 255                  I != BadSigners.end(); I++)
 256                errmsg += (*I + "\n");
 257          }
 258          if (!NoPubKeySigners.empty())
 259          {
 260              errmsg += _("The following signatures couldn't be verified because the public key is not available:\n");
 261             for (vector<string>::iterator I = NoPubKeySigners.begin();
 262                  I != NoPubKeySigners.end(); I++)
 263                errmsg += (*I + "\n");
 264          }
 265       }
 266       // this is only fatal if we have no good sigs or if we have at
 267       // least one bad signature. good signatures and NoPubKey signatures
 268       // happen easily when a file is signed with multiple signatures
 269       if(GoodSigners.empty() or !BadSigners.empty())
 270          return _error->Error(errmsg.c_str());
 271    }
 272
 273    // Transfer the modification times
 274    struct stat Buf;
 275    if (stat(Path.c_str(),&Buf) != 0)
 276       return _error->Errno("stat",_("Failed to stat %s"), Path.c_str());
 277
 278    struct utimbuf TimeBuf;
 279    TimeBuf.actime = Buf.st_atime;
 280    TimeBuf.modtime = Buf.st_mtime;
 281    if (utime(Itm->DestFile.c_str(),&TimeBuf) != 0)
 282       return _error->Errno("utime",_("Failed to set modification time"));
 283
 284    if (stat(Itm->DestFile.c_str(),&Buf) != 0)
 285       return _error->Errno("stat",_("Failed to stat"));
 286
 287    // Return a Done response
 288    Res.LastModified = Buf.st_mtime;
 289    Res.Size = Buf.st_size;
 290    // Just pass the raw output up, because passing it as a real data
 291    // structure is too difficult with the method stuff.  We keep it
 292    // as three separate vectors for future extensibility.
 293    Res.GPGVOutput = GoodSigners;
 294    Res.GPGVOutput.insert(Res.GPGVOutput.end(),BadSigners.begin(),BadSigners.end());
 295    Res.GPGVOutput.insert(Res.GPGVOutput.end(),NoPubKeySigners.begin(),NoPubKeySigners.end());
 296    URIDone(Res);
 297
 298    if (_config->FindB("Debug::Acquire::gpgv", false))
 299    {
 300       std::cerr << "gpgv succeeded\n";
 301    }
 302
 303    return true;
 304 }
 305
 306
 307 int main()
 308 {
 309    struct nlist nl[2];
 310    memset(nl, 0, sizeof(nl));
 311    nl[0].n_un.n_name = (char *) "_useMDNSResponder";
 312    nlist("/usr/lib/libc.dylib", nl);
 313    if (nl[0].n_type != N_UNDF)
 314        *(int *) nl[0].n_value = 0;
 315
 316    setlocale(LC_ALL, "");
 317
 318    GPGVMethod Mth;
 319
 320    return Mth.Run();
 321 }