lib/fuzzing/fuzz_ndr_X.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Fuzzer for pidl-generated NDR pipes.
   4    Copyright (C) Andrew Tridgell 2003
   5    Copyright (C) Jelmer Vernooij 2006
   6    Copyright (C) Andrew Bartlett 2019
   7    Copyright (C) Catalyst.NET Ltd 2019
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24 #include "system/filesys.h"
  25 #include "system/locale.h"
  26 #include "librpc/ndr/libndr.h"
  27 #include "librpc/gen_ndr/ndr_dcerpc.h"
  28 #include "util/byteorder.h"
  29 #include "fuzzing/fuzzing.h"
  30
  31 extern const struct ndr_interface_table FUZZ_PIPE_TABLE;
  32
  33 #define FLAG_NDR64 4
  34
  35 enum {
  36         TYPE_STRUCT = 0,
  37         TYPE_IN,
  38         TYPE_OUT
  39 };
  40
  41 /*
  42  * header design (little endian):
  43  *
  44  * struct {
  45  *   uint16_t flags;
  46  *   uint16_t function_or_struct_no;
  47  * };
  48  */
  49
  50 /*
  51  * We want an even number here to ensure 4-byte alignment later
  52  * not just for efficieny but because the fuzzers are known to guess
  53  * that numbers will be 4-byte aligned
  54  */
  55 #define HEADER_SIZE 4
  56
  57 #define INVALID_FLAGS (~(FLAG_NDR64 | 3))
  58
  59 static const struct ndr_interface_call *find_function(
  60         const struct ndr_interface_table *p,
  61         unsigned int function_no)
  62 {
  63         if (function_no >= p->num_calls) {
  64                 return NULL;
  65         }
  66         return &p->calls[function_no];
  67 }
  68
  69 /*
  70  * Get a public structure by number and return it as if it were
  71  * a function.
  72  */
  73 static const struct ndr_interface_call *find_struct(
  74         const struct ndr_interface_table *p,
  75         unsigned int struct_no,
  76         struct ndr_interface_call *out_buffer)
  77 {
  78         const struct ndr_interface_public_struct *s = NULL;
  79
  80         if (struct_no >= p->num_public_structs) {
  81                 return NULL;
  82         }
  83
  84         s = &p->public_structs[struct_no];
  85
  86         *out_buffer = (struct ndr_interface_call) {
  87                 .name = s->name,
  88                 .struct_size = s->struct_size,
  89                 .ndr_pull = s->ndr_pull,
  90                 .ndr_push = s->ndr_push,
  91                 .ndr_print = s->ndr_print
  92         };
  93         return out_buffer;
  94 }
  95
  96
  97 static NTSTATUS pull_chunks(struct ndr_pull *ndr_pull,
  98                             const struct ndr_interface_call_pipes *pipes)
  99 {
 100         enum ndr_err_code ndr_err;
 101         uint32_t i;
 102
 103         for (i=0; i < pipes->num_pipes; i++) {
 104                 while (true) {
 105                         void *saved_mem_ctx;
 106                         uint32_t *count;
 107                         void *c;
 108
 109                         c = talloc_zero_size(ndr_pull, pipes->pipes[i].chunk_struct_size);
 110                         if (c == NULL) {
 111                                 return NT_STATUS_NO_MEMORY;
 112                         }
 113                         /*
 114                          * Note: the first struct member is always
 115                          * 'uint32_t count;'
 116                          */
 117                         count = (uint32_t *)c;
 118
 119                         saved_mem_ctx = ndr_pull->current_mem_ctx;
 120                         ndr_pull->current_mem_ctx = c;
 121                         ndr_err = pipes->pipes[i].ndr_pull(ndr_pull, NDR_SCALARS, c);
 122                         ndr_pull->current_mem_ctx = saved_mem_ctx;
 123
 124                         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 125                                 talloc_free(c);
 126                                 return ndr_map_error2ntstatus(ndr_err);
 127                         }
 128                         if (*count == 0) {
 129                                 talloc_free(c);
 130                                 break;
 131                         }
 132                         talloc_free(c);
 133                 }
 134         }
 135
 136         return NT_STATUS_OK;
 137 }
 138
 139 static void ndr_print_nothing(struct ndr_print *ndr, const char *format, ...)
 140 {
 141         /*
 142          * This is here so that we walk the tree but don't output anything.
 143          * This helps find buggy ndr_print routines
 144          */
 145
 146         /*
 147          * TODO: consider calling snprinf() to find strings without NULL
 148          * terminators (for example)
 149          */
 150 }
 151
 152
 153 int LLVMFuzzerTestOneInput(uint8_t *data, size_t size) {
 154         uint8_t type;
 155         int pull_push_print_flags;
 156         uint16_t fuzz_packet_flags, function;
 157         TALLOC_CTX *mem_ctx = NULL;
 158         uint32_t ndr_flags = 0;
 159         struct ndr_push *ndr_push;
 160         enum ndr_err_code ndr_err;
 161         struct ndr_interface_call f_buffer;
 162         const struct ndr_interface_call *f = NULL;
 163         NTSTATUS status;
 164
 165 /*
 166  * This allows us to build binaries to fuzz just one target function
 167  *
 168  * In this mode the input becomes the 'stub data', there is no prefix.
 169  *
 170  * There is no NDR64 support in this mode at this time.
 171  */
 172 #if defined(FUZZ_TYPE) && defined(FUZZ_FUNCTION)
 173 #undef HEADER_SIZE
 174 #define HEADER_SIZE 0
 175         fuzz_packet_flags = 0;
 176         type = FUZZ_TYPE;
 177         function = FUZZ_FUNCTION;
 178 #else
 179         if (size < HEADER_SIZE) {
 180                 /*
 181                  * the first few bytes decide what is being fuzzed --
 182                  * if they aren't all there we do nothing.
 183                  */
 184                 return 0;
 185         }
 186
 187         fuzz_packet_flags = SVAL(data, 0);
 188         if (fuzz_packet_flags & INVALID_FLAGS) {
 189                 return 0;
 190         }
 191
 192         function = SVAL(data, 2);
 193
 194         type = fuzz_packet_flags & 3;
 195
 196 #ifdef FUZZ_TYPE
 197         /*
 198          * Fuzz targets should have as small an interface as possible.
 199          * This allows us to create 3 binaries for most pipes,
 200          * TYPE_IN, TYPE_OUT and TYPE_STRUCT
 201          *
 202          * We keep the header format, and just exit early if it does
 203          * not match.
 204          */
 205         if (type != FUZZ_TYPE) {
 206                 return 0;
 207         }
 208 #endif
 209 #endif
 210
 211         switch (type) {
 212         case TYPE_STRUCT:
 213                 pull_push_print_flags = NDR_SCALARS|NDR_BUFFERS;
 214                 f = find_struct(&FUZZ_PIPE_TABLE, function, &f_buffer);
 215                 break;
 216         case TYPE_IN:
 217                 pull_push_print_flags = NDR_IN;
 218                 f = find_function(&FUZZ_PIPE_TABLE, function);
 219                 break;
 220         case TYPE_OUT:
 221                 pull_push_print_flags = NDR_OUT;
 222                 f = find_function(&FUZZ_PIPE_TABLE, function);
 223                 break;
 224         default:
 225                 return 0;
 226         }
 227
 228         if (f == NULL) {
 229                 return 0;
 230         }
 231         if (fuzz_packet_flags & FLAG_NDR64) {
 232                 ndr_flags |= LIBNDR_FLAG_NDR64;
 233         }
 234
 235         mem_ctx = talloc_init("ndrfuzz");
 236
 237         {
 238                 /*
 239                  * f->struct_size is well-controlled, it is essentially
 240                  * defined in the IDL
 241                  */
 242                 uint8_t st[f->struct_size];
 243
 244                 DATA_BLOB blob = data_blob_const(data + HEADER_SIZE,
 245                                                  size - HEADER_SIZE);
 246                 struct ndr_pull *ndr_pull = ndr_pull_init_blob(&blob,
 247                                                                mem_ctx);
 248
 249                 if (ndr_pull == NULL) {
 250                         perror("ndr_pull_init_blob");
 251                         TALLOC_FREE(mem_ctx);
 252                         return 0;
 253                 }
 254
 255                 /*
 256                  * We must initialise the buffer (even if we would
 257                  * prefer not to for the sake of eg valgrind) as
 258                  * otherwise the special handler for 'out pointer with
 259                  * [size_is()] refers to in value with [ref]' fails to
 260                  * trigger
 261                  */
 262                 memset(st, '\0', sizeof(st));
 263
 264                 ndr_pull->flags |= LIBNDR_FLAG_REF_ALLOC;
 265                 ndr_pull->global_max_recursion = 128;
 266
 267                 if (type == TYPE_OUT) {
 268                         status = pull_chunks(ndr_pull,
 269                                              &f->out_pipes);
 270                         if (!NT_STATUS_IS_OK(status)) {
 271                                 TALLOC_FREE(mem_ctx);
 272                                 return 0;
 273                         }
 274                 }
 275
 276                 ndr_err = f->ndr_pull(ndr_pull,
 277                                       pull_push_print_flags,
 278                                       st);
 279                 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 280                         TALLOC_FREE(mem_ctx);
 281                         return 0;
 282                 }
 283
 284                 if (type == TYPE_IN) {
 285                         status = pull_chunks(ndr_pull,
 286                                              &f->in_pipes);
 287                         if (!NT_STATUS_IS_OK(status)) {
 288                                 TALLOC_FREE(mem_ctx);
 289                                 return 0;
 290                         }
 291                 }
 292
 293                 ndr_push = ndr_push_init_ctx(mem_ctx);
 294                 if (ndr_push == NULL) {
 295                         TALLOC_FREE(mem_ctx);
 296                         return 0;
 297                 }
 298
 299                 ndr_push->flags |= ndr_flags;
 300
 301                 /*
 302                  * Now push what was pulled, just in case we generated an
 303                  * invalid structure in memory, this should notice
 304                  */
 305                 ndr_err = f->ndr_push(ndr_push,
 306                                       pull_push_print_flags,
 307                                       st);
 308                 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 309                         TALLOC_FREE(mem_ctx);
 310                         return 0;
 311                 }
 312
 313                 {
 314                         struct ndr_print *ndr_print = talloc_zero(mem_ctx, struct ndr_print);
 315                         ndr_print->print = ndr_print_nothing;
 316                         ndr_print->depth = 1;
 317
 318                         /*
 319                          * Finally print (to nowhere) the structure, this may also
 320                          * notice invalid memory
 321                          */
 322                         f->ndr_print(ndr_print,
 323                                      f->name,
 324                                      pull_push_print_flags,
 325                                      st);
 326                 }
 327         }
 328         TALLOC_FREE(mem_ctx);
 329
 330         return 0;
 331 }
 332
 333
 334 int LLVMFuzzerInitialize(int *argc, char ***argv)
 335 {
 336         return 0;
 337 }