summaryrefslogtreecommitdiff
path: root/methods/gpgv.cc
blob: 06e1612e61998cbb2b24bca17052fb17dc38f10e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
#include <config.h>

#include <apt-pkg/acquire-method.h>
#include <apt-pkg/configuration.h>
#include <apt-pkg/error.h>
#include <apt-pkg/gpgv.h>
#include <apt-pkg/strutl.h>
#include <apt-pkg/fileutl.h>
#include "aptmethod.h"

#include <ctype.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>

#include <array>
#include <algorithm>
#include <sstream>
#include <iterator>
#include <iostream>
#include <string>
#include <vector>

#include <apti18n.h>

using std::string;
using std::vector;

#define GNUPGPREFIX "[GNUPG:]"
#define GNUPGBADSIG "[GNUPG:] BADSIG"
#define GNUPGNOPUBKEY "[GNUPG:] NO_PUBKEY"
#define GNUPGVALIDSIG "[GNUPG:] VALIDSIG"
#define GNUPGGOODSIG "[GNUPG:] GOODSIG"
#define GNUPGKEYEXPIRED "[GNUPG:] KEYEXPIRED"
#define GNUPGREVKEYSIG "[GNUPG:] REVKEYSIG"
#define GNUPGNODATA "[GNUPG:] NODATA"

static const std::array<string, 1> WeakDigests {
   "1", // MD5
// "2", // SHA1
// "3", // RIPEMD-160
};

class GPGVMethod : public aptMethod
{
   private:
   string VerifyGetSigners(const char *file, const char *outfile,
				std::string const &key,
				vector<string> &GoodSigners,
                                vector<string> &BadSigners,
                                vector<string> &WorthlessSigners,
				vector<string> &NoPubKeySigners);
   
   protected:
   virtual bool URIAcquire(std::string const &Message, FetchItem *Itm) APT_OVERRIDE;
   public:
   
   GPGVMethod() : aptMethod("gpgv","1.0",SingleInstance | SendConfig) {};
};

string GPGVMethod::VerifyGetSigners(const char *file, const char *outfile,
					 std::string const &key,
					 vector<string> &GoodSigners,
					 vector<string> &BadSigners,
					 vector<string> &WorthlessSigners,
					 vector<string> &NoPubKeySigners)
{
   bool const Debug = _config->FindB("Debug::Acquire::gpgv", false);

   if (Debug == true)
      std::clog << "inside VerifyGetSigners" << std::endl;

   int fd[2];
   bool const keyIsID = (key.empty() == false && key[0] != '/');

   if (pipe(fd) < 0)
      return "Couldn't create pipe";

   pid_t pid = fork();
   if (pid < 0)
      return string("Couldn't spawn new process") + strerror(errno);
   else if (pid == 0)
      ExecGPGV(outfile, file, 3, fd, (keyIsID ? "" : key));
   close(fd[1]);

   FILE *pipein = fdopen(fd[0], "r");

   // Loop over the output of apt-key (which really is gnupg), and check the signatures.
   std::vector<std::string> ValidSigners;
   size_t buffersize = 0;
   char *buffer = NULL;
   while (1)
   {
      if (getline(&buffer, &buffersize, pipein) == -1)
	 break;
      if (Debug == true)
         std::clog << "Read: " << buffer << std::endl;

      // Push the data into three separate vectors, which
      // we later concatenate.  They're kept separate so
      // if we improve the apt method communication stuff later
      // it will be better.
      if (strncmp(buffer, GNUPGBADSIG, sizeof(GNUPGBADSIG)-1) == 0)
      {
         if (Debug == true)
            std::clog << "Got BADSIG! " << std::endl;
         BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
      }
      else if (strncmp(buffer, GNUPGNOPUBKEY, sizeof(GNUPGNOPUBKEY)-1) == 0)
      {
         if (Debug == true)
            std::clog << "Got NO_PUBKEY " << std::endl;
         NoPubKeySigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
      }
      else if (strncmp(buffer, GNUPGNODATA, sizeof(GNUPGBADSIG)-1) == 0)
      {
         if (Debug == true)
            std::clog << "Got NODATA! " << std::endl;
         BadSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
      }
      else if (strncmp(buffer, GNUPGKEYEXPIRED, sizeof(GNUPGKEYEXPIRED)-1) == 0)
      {
         if (Debug == true)
            std::clog << "Got KEYEXPIRED! " << std::endl;
         WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
      }
      else if (strncmp(buffer, GNUPGREVKEYSIG, sizeof(GNUPGREVKEYSIG)-1) == 0)
      {
         if (Debug == true)
            std::clog << "Got REVKEYSIG! " << std::endl;
         WorthlessSigners.push_back(string(buffer+sizeof(GNUPGPREFIX)));
      }
      else if (strncmp(buffer, GNUPGGOODSIG, sizeof(GNUPGGOODSIG)-1) == 0)
      {
         char *sig = buffer + sizeof(GNUPGPREFIX);
         char *p = sig + sizeof("GOODSIG");
         while (*p && isxdigit(*p)) 
            p++;
         *p = 0;
         if (Debug == true)
            std::clog << "Got GOODSIG, key ID:" << sig << std::endl;
         GoodSigners.push_back(string(sig));
      }
      else if (strncmp(buffer, GNUPGVALIDSIG, sizeof(GNUPGVALIDSIG)-1) == 0)
      {
         char *sig = buffer + sizeof(GNUPGVALIDSIG);
         std::istringstream iss((string(sig)));
         vector<string> tokens{std::istream_iterator<string>{iss},
                               std::istream_iterator<string>{}};
         char *p = sig;
         while (*p && isxdigit(*p))
            p++;
         *p = 0;
         if (Debug == true)
            std::clog << "Got VALIDSIG, key ID: " << sig << std::endl;
         // Reject weak digest algorithms
         if (std::find(WeakDigests.begin(), WeakDigests.end(), tokens[7]) != WeakDigests.end())
            BadSigners.push_back(string(sig));

         ValidSigners.push_back(string(sig));
      }
   }
   fclose(pipein);
   free(buffer);

   // apt-key has a --keyid parameter, but this requires gpg, so we call it without it
   // and instead check after the fact which keyids where used for verification
   if (keyIsID == true)
   {
      if (Debug == true)
	 std::clog << "GoodSigs needs to be limited to keyid " << key << std::endl;
      std::vector<std::string>::iterator const foundItr = std::find(ValidSigners.begin(), ValidSigners.end(), key);
      bool const found = (foundItr != ValidSigners.end());
      std::copy(GoodSigners.begin(), GoodSigners.end(), std::back_insert_iterator<std::vector<std::string> >(NoPubKeySigners));
      if (found)
      {
	 // we look for GOODSIG here as well as an expired sig is a valid sig as well (but not a good one)
	 std::string const goodlongkeyid = "GOODSIG " + key.substr(24, 16);
	 bool const foundGood = std::find(GoodSigners.begin(), GoodSigners.end(), goodlongkeyid) != GoodSigners.end();
	 if (Debug == true)
	    std::clog << "Key " << key << " is valid sig, is " << goodlongkeyid << " also a good one? " << (foundGood ? "yes" : "no") << std::endl;
	 GoodSigners.clear();
	 if (foundGood)
	 {
	    GoodSigners.push_back(goodlongkeyid);
	    NoPubKeySigners.erase(std::remove(NoPubKeySigners.begin(), NoPubKeySigners.end(), goodlongkeyid), NoPubKeySigners.end());
	 }
      }
      else
	 GoodSigners.clear();
   }

   int status;
   waitpid(pid, &status, 0);
   if (Debug == true)
   {
      ioprintf(std::clog, "gpgv exited with status %i\n", WEXITSTATUS(status));
   }
   
   if (WEXITSTATUS(status) == 0)
   {
      if (keyIsID)
      {
	 // gpgv will report success, but we want to enforce a certain keyring
	 // so if we haven't found the key the valid we found is in fact invalid
	 if (GoodSigners.empty())
	    return _("At least one invalid signature was encountered.");
      }
      else
      {
	 if (GoodSigners.empty())
	    return _("Internal error: Good signature, but could not determine key fingerprint?!");
      }
      return "";
   }
   else if (WEXITSTATUS(status) == 1)
      return _("At least one invalid signature was encountered.");
   else if (WEXITSTATUS(status) == 111)
      return _("Could not execute 'apt-key' to verify signature (is gnupg installed?)");
   else if (WEXITSTATUS(status) == 112)
   {
      // acquire system checks for "NODATA" to generate GPG errors (the others are only warnings)
      std::string errmsg;
      //TRANSLATORS: %s is a single techy word like 'NODATA'
      strprintf(errmsg, _("Clearsigned file isn't valid, got '%s' (does the network require authentication?)"), "NODATA");
      return errmsg;
   }
   else
      return _("Unknown error executing apt-key");
}

bool GPGVMethod::URIAcquire(std::string const &Message, FetchItem *Itm)
{
   URI const Get = Itm->Uri;
   string const Path = Get.Host + Get.Path; // To account for relative paths
   std::string const key = LookupTag(Message, "Signed-By");
   vector<string> GoodSigners;
   vector<string> BadSigners;
   // a worthless signature is a expired or revoked one
   vector<string> WorthlessSigners;
   vector<string> NoPubKeySigners;
   
   FetchResult Res;
   Res.Filename = Itm->DestFile;
   URIStart(Res);

   // Run apt-key on file, extract contents and get the key ID of the signer
   string msg = VerifyGetSigners(Path.c_str(), Itm->DestFile.c_str(), key,
                                 GoodSigners, BadSigners, WorthlessSigners,
                                 NoPubKeySigners);
   if (GoodSigners.empty() || !BadSigners.empty() || !NoPubKeySigners.empty())
   {
      string errmsg;
      // In this case, something bad probably happened, so we just go
      // with what the other method gave us for an error message.
      if (BadSigners.empty() && WorthlessSigners.empty() && NoPubKeySigners.empty())
         errmsg = msg;
      else
      {
         if (!BadSigners.empty())
         {
            errmsg += _("The following signatures were invalid:\n");
            for (vector<string>::iterator I = BadSigners.begin();
		 I != BadSigners.end(); ++I)
               errmsg += (*I + "\n");
         }
         if (!WorthlessSigners.empty())
         {
            errmsg += _("The following signatures were invalid:\n");
            for (vector<string>::iterator I = WorthlessSigners.begin();
		 I != WorthlessSigners.end(); ++I)
               errmsg += (*I + "\n");
         }
         if (!NoPubKeySigners.empty())
         {
             errmsg += _("The following signatures couldn't be verified because the public key is not available:\n");
            for (vector<string>::iterator I = NoPubKeySigners.begin();
		 I != NoPubKeySigners.end(); ++I)
               errmsg += (*I + "\n");
         }
      }
      // this is only fatal if we have no good sigs or if we have at
      // least one bad signature. good signatures and NoPubKey signatures
      // happen easily when a file is signed with multiple signatures
      if(GoodSigners.empty() or !BadSigners.empty())
      	 return _error->Error("%s", errmsg.c_str());
   }
      
   // Just pass the raw output up, because passing it as a real data
   // structure is too difficult with the method stuff.  We keep it
   // as three separate vectors for future extensibility.
   Res.GPGVOutput = GoodSigners;
   Res.GPGVOutput.insert(Res.GPGVOutput.end(),BadSigners.begin(),BadSigners.end());
   Res.GPGVOutput.insert(Res.GPGVOutput.end(),NoPubKeySigners.begin(),NoPubKeySigners.end());
   URIDone(Res);

   if (_config->FindB("Debug::Acquire::gpgv", false))
   {
      std::clog << "apt-key succeeded\n";
   }

   return true;
}


int main()
{
   setlocale(LC_ALL, "");

   GPGVMethod Mth;

   return Mth.Run();
}