apt-pkg/contrib/gpgv.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Include Files                                                        /*{{{*/
   3 #include<config.h>
   4
   5 #include<apt-pkg/configuration.h>
   6 #include<apt-pkg/error.h>
   7 #include<apt-pkg/strutl.h>
   8 #include<apt-pkg/fileutl.h>
   9 #include<apt-pkg/gpgv.h>
  10
  11 #include <errno.h>
  12 #include <stdio.h>
  13 #include <string.h>
  14 #include <stdlib.h>
  15 #include <fcntl.h>
  16 #include <sys/wait.h>
  17 #include <unistd.h>
  18 #include <stddef.h>
  19 #include <iostream>
  20 #include <string>
  21 #include <vector>
  22
  23 #include <apti18n.h>
  24                                                                         /*}}}*/
  25 static char * GenerateTemporaryFileTemplate(const char *basename)       /*{{{*/
  26 {
  27    std::string out;
  28    std::string tmpdir = GetTempDir();
  29    strprintf(out,  "%s/%s.XXXXXX", tmpdir.c_str(), basename);
  30    return strdup(out.c_str());
  31 }
  32                                                                         /*}}}*/
  33 // ExecGPGV - returns the command needed for verify                     /*{{{*/
  34 // ---------------------------------------------------------------------
  35 /* Generating the commandline for calling gpg is somehow complicated as
  36    we need to add multiple keyrings and user supplied options.
  37    Also, as gpg has no options to enforce a certain reduced style of
  38    clear-signed files (=the complete content of the file is signed and
  39    the content isn't encoded) we do a divide and conquer approach here
  40    and split up the clear-signed file in message and signature for gpg.
  41    And as a cherry on the cake, we use our apt-key wrapper to do part
  42    of the lifting in regards to merging keyrings. Fun for the whole family.
  43 */
  44 void ExecGPGV(std::string const &File, std::string const &FileGPG,
  45              int const &statusfd, int fd[2])
  46 {
  47    #define EINTERNAL 111
  48    std::string const aptkey = _config->FindFile("Dir::Bin::apt-key", "/usr/bin/apt-key");
  49
  50    bool const Debug = _config->FindB("Debug::Acquire::gpgv", false);
  51
  52    std::vector<const char *> Args;
  53    Args.reserve(10);
  54
  55    Args.push_back(aptkey.c_str());
  56    Args.push_back("--quiet");
  57    Args.push_back("adv");
  58
  59    char statusfdstr[10];
  60    if (statusfd != -1)
  61    {
  62       Args.push_back("--status-fd");
  63       snprintf(statusfdstr, sizeof(statusfdstr), "%i", statusfd);
  64       Args.push_back(statusfdstr);
  65    }
  66
  67    Configuration::Item const *Opts;
  68    Opts = _config->Tree("Acquire::gpgv::Options");
  69    if (Opts != 0)
  70    {
  71       Opts = Opts->Child;
  72       for (; Opts != 0; Opts = Opts->Next)
  73       {
  74          if (Opts->Value.empty() == true)
  75             continue;
  76          Args.push_back(Opts->Value.c_str());
  77       }
  78    }
  79    Args.push_back("--verify");
  80
  81    enum  { DETACHED, CLEARSIGNED } releaseSignature = (FileGPG != File) ? DETACHED : CLEARSIGNED;
  82    std::vector<std::string> dataHeader;
  83    char * sig = NULL;
  84    char * data = NULL;
  85
  86    if (releaseSignature == DETACHED)
  87    {
  88       Args.push_back(FileGPG.c_str());
  89       Args.push_back(File.c_str());
  90    }
  91    else // clear-signed file
  92    {
  93       sig = GenerateTemporaryFileTemplate("apt.sig");
  94       data = GenerateTemporaryFileTemplate("apt.data");
  95       if (sig == NULL || data == NULL)
  96       {
  97          ioprintf(std::cerr, "Couldn't create tempfile names for splitting up %s", File.c_str());
  98          exit(EINTERNAL);
  99       }
 100
 101       int const sigFd = mkstemp(sig);
 102       int const dataFd = mkstemp(data);
 103       if (sigFd == -1 || dataFd == -1)
 104       {
 105          if (dataFd != -1)
 106             unlink(sig);
 107          if (sigFd != -1)
 108             unlink(data);
 109          ioprintf(std::cerr, "Couldn't create tempfiles for splitting up %s", File.c_str());
 110          exit(EINTERNAL);
 111       }
 112
 113       FileFd signature;
 114       signature.OpenDescriptor(sigFd, FileFd::WriteOnly, true);
 115       FileFd message;
 116       message.OpenDescriptor(dataFd, FileFd::WriteOnly, true);
 117
 118       if (signature.Failed() == true || message.Failed() == true ||
 119             SplitClearSignedFile(File, &message, &dataHeader, &signature) == false)
 120       {
 121          if (dataFd != -1)
 122             unlink(sig);
 123          if (sigFd != -1)
 124             unlink(data);
 125          ioprintf(std::cerr, "Splitting up %s into data and signature failed", File.c_str());
 126          exit(112);
 127       }
 128       Args.push_back(sig);
 129       Args.push_back(data);
 130    }
 131
 132    Args.push_back(NULL);
 133
 134    if (Debug == true)
 135    {
 136       std::clog << "Preparing to exec: ";
 137       for (std::vector<const char *>::const_iterator a = Args.begin(); *a != NULL; ++a)
 138          std::clog << " " << *a;
 139       std::clog << std::endl;
 140    }
 141
 142    if (statusfd != -1)
 143    {
 144       int const nullfd = open("/dev/null", O_WRONLY);
 145       close(fd[0]);
 146       // Redirect output to /dev/null; we read from the status fd
 147       if (statusfd != STDOUT_FILENO)
 148          dup2(nullfd, STDOUT_FILENO);
 149       if (statusfd != STDERR_FILENO)
 150          dup2(nullfd, STDERR_FILENO);
 151       // Redirect the pipe to the status fd (3)
 152       dup2(fd[1], statusfd);
 153
 154       putenv((char *)"LANG=");
 155       putenv((char *)"LC_ALL=");
 156       putenv((char *)"LC_MESSAGES=");
 157    }
 158
 159    if (releaseSignature == DETACHED)
 160    {
 161       execvp(Args[0], (char **) &Args[0]);
 162       ioprintf(std::cerr, "Couldn't execute %s to check %s", Args[0], File.c_str());
 163       exit(EINTERNAL);
 164    }
 165    else
 166    {
 167 //#define UNLINK_EXIT(X) exit(X)
 168 #define UNLINK_EXIT(X) unlink(sig);unlink(data);exit(X)
 169
 170       // for clear-signed files we have created tempfiles we have to clean up
 171       // and we do an additional check, so fork yet another time …
 172       pid_t pid = ExecFork();
 173       if(pid < 0) {
 174          ioprintf(std::cerr, "Fork failed for %s to check %s", Args[0], File.c_str());
 175          UNLINK_EXIT(EINTERNAL);
 176       }
 177       if(pid == 0)
 178       {
 179          if (statusfd != -1)
 180             dup2(fd[1], statusfd);
 181          execvp(Args[0], (char **) &Args[0]);
 182          ioprintf(std::cerr, "Couldn't execute %s to check %s", Args[0], File.c_str());
 183          UNLINK_EXIT(EINTERNAL);
 184       }
 185
 186       // Wait and collect the error code - taken from WaitPid as we need the exact Status
 187       int Status;
 188       while (waitpid(pid,&Status,0) != pid)
 189       {
 190          if (errno == EINTR)
 191             continue;
 192          ioprintf(std::cerr, _("Waited for %s but it wasn't there"), "apt-key");
 193          UNLINK_EXIT(EINTERNAL);
 194       }
 195 #undef UNLINK_EXIT
 196       // we don't need the files any longer
 197       unlink(sig);
 198       unlink(data);
 199       free(sig);
 200       free(data);
 201
 202       // check if it exit'ed normally …
 203       if (WIFEXITED(Status) == false)
 204       {
 205          ioprintf(std::cerr, _("Sub-process %s exited unexpectedly"), "apt-key");
 206          exit(EINTERNAL);
 207       }
 208
 209       // … and with a good exit code
 210       if (WEXITSTATUS(Status) != 0)
 211       {
 212          ioprintf(std::cerr, _("Sub-process %s returned an error code (%u)"), "apt-key", WEXITSTATUS(Status));
 213          exit(WEXITSTATUS(Status));
 214       }
 215
 216       // everything fine
 217       exit(0);
 218    }
 219    exit(EINTERNAL); // unreachable safe-guard
 220 }
 221                                                                         /*}}}*/
 222 // SplitClearSignedFile - split message into data/signature             /*{{{*/
 223 bool SplitClearSignedFile(std::string const &InFile, FileFd * const ContentFile,
 224       std::vector<std::string> * const ContentHeader, FileFd * const SignatureFile)
 225 {
 226    FILE *in = fopen(InFile.c_str(), "r");
 227    if (in == NULL)
 228       return _error->Errno("fopen", "can not open %s", InFile.c_str());
 229
 230    bool found_message_start = false;
 231    bool found_message_end = false;
 232    bool skip_until_empty_line = false;
 233    bool found_signature = false;
 234    bool first_line = true;
 235
 236    char *buf = NULL;
 237    size_t buf_size = 0;
 238    while (getline(&buf, &buf_size, in) != -1)
 239    {
 240       _strrstrip(buf);
 241       if (found_message_start == false)
 242       {
 243          if (strcmp(buf, "-----BEGIN PGP SIGNED MESSAGE-----") == 0)
 244          {
 245             found_message_start = true;
 246             skip_until_empty_line = true;
 247          }
 248       }
 249       else if (skip_until_empty_line == true)
 250       {
 251          if (strlen(buf) == 0)
 252             skip_until_empty_line = false;
 253          // save "Hash" Armor Headers, others aren't allowed
 254          else if (ContentHeader != NULL && strncmp(buf, "Hash: ", strlen("Hash: ")) == 0)
 255             ContentHeader->push_back(buf);
 256       }
 257       else if (found_signature == false)
 258       {
 259          if (strcmp(buf, "-----BEGIN PGP SIGNATURE-----") == 0)
 260          {
 261             found_signature = true;
 262             found_message_end = true;
 263             if (SignatureFile != NULL)
 264             {
 265                SignatureFile->Write(buf, strlen(buf));
 266                SignatureFile->Write("\n", 1);
 267             }
 268          }
 269          else if (found_message_end == false) // we are in the message block
 270          {
 271             // we don't have any fields which need dash-escaped,
 272             // but implementations are free to encode all lines …
 273             char const * dashfree = buf;
 274             if (strncmp(dashfree, "- ", 2) == 0)
 275                dashfree += 2;
 276             if(first_line == true) // first line does not need a newline
 277                first_line = false;
 278             else if (ContentFile != NULL)
 279                ContentFile->Write("\n", 1);
 280             else
 281                continue;
 282             if (ContentFile != NULL)
 283                ContentFile->Write(dashfree, strlen(dashfree));
 284          }
 285       }
 286       else if (found_signature == true)
 287       {
 288          if (SignatureFile != NULL)
 289          {
 290             SignatureFile->Write(buf, strlen(buf));
 291             SignatureFile->Write("\n", 1);
 292          }
 293          if (strcmp(buf, "-----END PGP SIGNATURE-----") == 0)
 294             found_signature = false; // look for other signatures
 295       }
 296       // all the rest is whitespace, unsigned garbage or additional message blocks we ignore
 297    }
 298    fclose(in);
 299
 300    if (found_signature == true)
 301       return _error->Error("Signature in file %s wasn't closed", InFile.c_str());
 302
 303    // if we haven't found any of them, this an unsigned file,
 304    // so don't generate an error, but splitting was unsuccessful none-the-less
 305    if (first_line == true && found_message_start == false && found_message_end == false)
 306       return false;
 307    // otherwise one missing indicates a syntax error
 308    else if (first_line == true || found_message_start == false || found_message_end == false)
 309      return _error->Error("Splitting of file %s failed as it doesn't contain all expected parts %i %i %i", InFile.c_str(), first_line, found_message_start, found_message_end);
 310
 311    return true;
 312 }
 313                                                                         /*}}}*/
 314 bool OpenMaybeClearSignedFile(std::string const &ClearSignedFileName, FileFd &MessageFile) /*{{{*/
 315 {
 316    char * const message = GenerateTemporaryFileTemplate("fileutl.message");
 317    int const messageFd = mkstemp(message);
 318    if (messageFd == -1)
 319    {
 320       free(message);
 321       return _error->Errno("mkstemp", "Couldn't create temporary file to work with %s", ClearSignedFileName.c_str());
 322    }
 323    // we have the fd, thats enough for us
 324    unlink(message);
 325    free(message);
 326
 327    MessageFile.OpenDescriptor(messageFd, FileFd::ReadWrite, true);
 328    if (MessageFile.Failed() == true)
 329       return _error->Error("Couldn't open temporary file to work with %s", ClearSignedFileName.c_str());
 330
 331    _error->PushToStack();
 332    bool const splitDone = SplitClearSignedFile(ClearSignedFileName, &MessageFile, NULL, NULL);
 333    bool const errorDone = _error->PendingError();
 334    _error->MergeWithStack();
 335    if (splitDone == false)
 336    {
 337       MessageFile.Close();
 338
 339       if (errorDone == true)
 340          return false;
 341
 342       // we deal with an unsigned file
 343       MessageFile.Open(ClearSignedFileName, FileFd::ReadOnly);
 344    }
 345    else // clear-signed
 346    {
 347       if (MessageFile.Seek(0) == false)
 348          return _error->Errno("lseek", "Unable to seek back in message for file %s", ClearSignedFileName.c_str());
 349    }
 350
 351    return MessageFile.Failed() == false;
 352 }
 353                                                                         /*}}}*/