1
0
mirror of https://github.com/samba-team/samba.git synced 2024-12-22 13:34:15 +03:00
samba-mirror/lib/fuzzing/fuzz_ndr_X.c
Andrew Bartlett 66d12eb98a lib/fuzzing: Initialise st buffer in fuzz_ndr_X
An NDR pull of a function will fill in either the in. or out.
elements of this structure, but never both.

However, some structures have size_is() in the out. that reference
the in. elements.  This is the reason for the --context-file option
in ndrdump.

We have a special handler in the fuzzing case embedded in the
pidl-generated output to cope with this, by filling in pointers
for elements declared [ref,in] but it relies on the in-side
(at least) of the buffer being zeroed.

So zero the buffer before we start.  Sadly this means things
like valgrind can not find a use of uninitialised data, but that
is a price we have to pay.

Credit to OSS-Fuzz

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
2019-12-18 06:39:26 +00:00

331 lines
7.4 KiB
C

/*
Unix SMB/CIFS implementation.
SMB torture tester
Copyright (C) Andrew Tridgell 2003
Copyright (C) Jelmer Vernooij 2006
Copyright (C) Andrew Bartlett 2019
Copyright (C) Catalyst.NET Ltd 2019
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "system/filesys.h"
#include "system/locale.h"
#include "librpc/ndr/libndr.h"
#include "librpc/gen_ndr/ndr_dcerpc.h"
#include "util/byteorder.h"
#include "fuzzing/fuzzing.h"
extern const struct ndr_interface_table FUZZ_PIPE_TABLE;
#define FLAG_NDR64 4
enum {
TYPE_STRUCT = 0,
TYPE_IN,
TYPE_OUT
};
/*
* header design (little endian):
*
* struct {
* uint16_t flags;
* uint16_t function_or_struct_no;
* };
*/
/*
* We want an even number here to ensure 4-byte alignment later
* not just for efficieny but because the fuzzers are known to guess
* that numbers will be 4-byte aligned
*/
#define HEADER_SIZE 4
#define INVALID_FLAGS (~(FLAG_NDR64 | 3))
static const struct ndr_interface_call *find_function(
const struct ndr_interface_table *p,
unsigned int function_no)
{
if (function_no >= p->num_calls) {
return NULL;
}
return &p->calls[function_no];
}
/*
* Get a public structure by number and return it as if it were
* a function.
*/
static const struct ndr_interface_call *find_struct(
const struct ndr_interface_table *p,
unsigned int struct_no,
struct ndr_interface_call *out_buffer)
{
const struct ndr_interface_public_struct *s = NULL;
if (struct_no >= p->num_public_structs) {
return NULL;
}
s = &p->public_structs[struct_no];
*out_buffer = (struct ndr_interface_call) {
.name = s->name,
.struct_size = s->struct_size,
.ndr_pull = s->ndr_pull,
.ndr_push = s->ndr_push,
.ndr_print = s->ndr_print
};
return out_buffer;
}
static NTSTATUS pull_chunks(struct ndr_pull *ndr_pull,
const struct ndr_interface_call_pipes *pipes)
{
enum ndr_err_code ndr_err;
uint32_t i;
for (i=0; i < pipes->num_pipes; i++) {
while (true) {
void *saved_mem_ctx;
uint32_t *count;
void *c;
c = talloc_zero_size(ndr_pull, pipes->pipes[i].chunk_struct_size);
if (c == NULL) {
return NT_STATUS_NO_MEMORY;
}
/*
* Note: the first struct member is always
* 'uint32_t count;'
*/
count = (uint32_t *)c;
saved_mem_ctx = ndr_pull->current_mem_ctx;
ndr_pull->current_mem_ctx = c;
ndr_err = pipes->pipes[i].ndr_pull(ndr_pull, NDR_SCALARS, c);
ndr_pull->current_mem_ctx = saved_mem_ctx;
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
talloc_free(c);
return ndr_map_error2ntstatus(ndr_err);
}
if (*count == 0) {
talloc_free(c);
break;
}
talloc_free(c);
}
}
return NT_STATUS_OK;
}
static void ndr_print_nothing(struct ndr_print *ndr, const char *format, ...)
{
/*
* This is here so that we walk the tree but don't output anything.
* This helps find buggy ndr_print routines
*/
/*
* TODO: consider calling snprinf() to find strings without NULL
* terminators (for example)
*/
}
int LLVMFuzzerTestOneInput(uint8_t *data, size_t size) {
uint8_t type;
int pull_push_print_flags;
uint16_t fuzz_packet_flags, function;
TALLOC_CTX *mem_ctx = NULL;
uint32_t ndr_flags = 0;
struct ndr_push *ndr_push;
enum ndr_err_code ndr_err;
struct ndr_interface_call f_buffer;
const struct ndr_interface_call *f = NULL;
NTSTATUS status;
/*
* This allows us to build binaries to fuzz just one target function
*
* In this mode the input becomes the 'stub data', there is no prefix.
*
* There is no NDR64 support in this mode at this time.
*/
#if defined(FUZZ_TYPE) && defined(FUZZ_FUNCTION)
#undef HEADER_SIZE
#define HEADER_SIZE 0
fuzz_packet_flags = 0;
type = FUZZ_TYPE;
function = FUZZ_FUNCTION;
#else
if (size < HEADER_SIZE) {
/*
* the first few bytes decide what is being fuzzed --
* if they aren't all there we do nothing.
*/
return 0;
}
fuzz_packet_flags = SVAL(data, 0);
if (fuzz_packet_flags & INVALID_FLAGS) {
return 0;
}
function = SVAL(data, 2);
type = fuzz_packet_flags & 3;
#ifdef FUZZ_TYPE
/*
* Fuzz targets should have as small an interface as possible.
* This allows us to create 3 binaries for most pipes,
* TYPE_IN, TYPE_OUT and TYPE_STRUCT
*
* We keep the header format, and just exit early if it does
* not match.
*/
if (type != FUZZ_TYPE) {
return 0;
}
#endif
#endif
switch (type) {
case TYPE_STRUCT:
pull_push_print_flags = NDR_SCALARS|NDR_BUFFERS;
f = find_struct(&FUZZ_PIPE_TABLE, function, &f_buffer);
break;
case TYPE_IN:
pull_push_print_flags = NDR_IN;
f = find_function(&FUZZ_PIPE_TABLE, function);
break;
case TYPE_OUT:
pull_push_print_flags = NDR_OUT;
f = find_function(&FUZZ_PIPE_TABLE, function);
break;
default:
return 0;
}
if (f == NULL) {
return 0;
}
if (fuzz_packet_flags & FLAG_NDR64) {
ndr_flags |= LIBNDR_FLAG_NDR64;
}
mem_ctx = talloc_init("ndrfuzz");
{
/*
* f->struct_size is well-controlled, it is essentially
* defined in the IDL
*/
uint8_t st[f->struct_size];
DATA_BLOB blob = data_blob_const(data + HEADER_SIZE,
size - HEADER_SIZE);
struct ndr_pull *ndr_pull = ndr_pull_init_blob(&blob,
mem_ctx);
if (ndr_pull == NULL) {
perror("ndr_pull_init_blob");
TALLOC_FREE(mem_ctx);
return 0;
}
/*
* We must initialise the buffer (even if we would
* prefer not to for the sake of eg valgrind) as
* otherwise the special handler for 'out pointer with
* [size_is()] refers to in value with [ref]' fails to
* trigger
*/
memset(st, '\0', sizeof(st));
ndr_pull->flags |= LIBNDR_FLAG_REF_ALLOC;
if (type == TYPE_OUT) {
status = pull_chunks(ndr_pull,
&f->out_pipes);
if (!NT_STATUS_IS_OK(status)) {
TALLOC_FREE(mem_ctx);
return 0;
}
}
ndr_err = f->ndr_pull(ndr_pull,
pull_push_print_flags,
st);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
TALLOC_FREE(mem_ctx);
return 0;
}
if (type == TYPE_IN) {
status = pull_chunks(ndr_pull,
&f->in_pipes);
if (!NT_STATUS_IS_OK(status)) {
TALLOC_FREE(mem_ctx);
return 0;
}
}
ndr_push = ndr_push_init_ctx(mem_ctx);
if (ndr_push == NULL) {
TALLOC_FREE(mem_ctx);
return 0;
}
ndr_push->flags |= ndr_flags;
/*
* Now push what was pulled, just in case we generated an
* invalid structure in memory, this should notice
*/
ndr_err = f->ndr_push(ndr_push,
pull_push_print_flags,
st);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
TALLOC_FREE(mem_ctx);
return 0;
}
{
struct ndr_print *ndr_print = talloc_zero(mem_ctx, struct ndr_print);
ndr_print->print = ndr_print_nothing;
ndr_print->depth = 1;
/*
* Finally print (to nowhere) the structure, this may also
* notice invalid memory
*/
f->ndr_print(ndr_print,
f->name,
pull_push_print_flags,
st);
}
}
TALLOC_FREE(mem_ctx);
return 0;
}