2 Unix SMB/CIFS implementation.
4 Copyright (C) Jeremy Allison 2003.
5 Copyright (C) Andrew Bartlett <abartlet@samba.org> 2002-2003
6 Copyright (C) Stefan Metzmacher 2009
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>.
23 #include "../lib/crypto/md5.h"
24 #include "smb_common.h"
25 #include "smb_signing.h"
27 /* Used by the SMB signing functions. */
29 struct smb_signing_state {
30 /* is signing localy allowed */
33 /* is signing localy desired */
36 /* is signing localy mandatory */
39 /* is signing negotiated by the peer */
42 bool active; /* Have I ever seen a validly signed packet? */
44 /* mac_key.length > 0 means signing is started */
47 /* the next expected seqnum */
51 void *(*alloc_fn)(TALLOC_CTX *mem_ctx, size_t len);
52 void (*free_fn)(TALLOC_CTX *mem_ctx, void *ptr);
55 static void smb_signing_reset_info(struct smb_signing_state *si)
61 si->free_fn(si->mem_ctx, si->mac_key.data);
63 talloc_free(si->mac_key.data);
65 si->mac_key.data = NULL;
66 si->mac_key.length = 0;
69 struct smb_signing_state *smb_signing_init_ex(TALLOC_CTX *mem_ctx,
73 void *(*alloc_fn)(TALLOC_CTX *, size_t),
74 void (*free_fn)(TALLOC_CTX *, void *))
76 struct smb_signing_state *si;
79 void *p = alloc_fn(mem_ctx, sizeof(struct smb_signing_state));
83 memset(p, 0, sizeof(struct smb_signing_state));
84 si = (struct smb_signing_state *)p;
85 si->mem_ctx = mem_ctx;
86 si->alloc_fn = alloc_fn;
87 si->free_fn = free_fn;
89 si = talloc_zero(mem_ctx, struct smb_signing_state);
103 si->allowed = allowed;
104 si->desired = desired;
105 si->mandatory = mandatory;
110 struct smb_signing_state *smb_signing_init(TALLOC_CTX *mem_ctx,
115 return smb_signing_init_ex(mem_ctx, allowed, desired, mandatory,
119 static bool smb_signing_good(struct smb_signing_state *si,
120 bool good, uint32_t seq)
129 if (!si->mandatory && !si->active) {
130 /* Non-mandatory signing - just turn off if this is the first bad packet.. */
131 DEBUG(5, ("smb_signing_good: signing negotiated but not required and peer\n"
132 "isn't sending correct signatures. Turning off.\n"));
133 smb_signing_reset_info(si);
137 /* Mandatory signing or bad packet after signing started - fail and disconnect. */
138 DEBUG(0, ("smb_signing_good: BAD SIG: seq %u\n", (unsigned int)seq));
142 static void smb_signing_md5(const DATA_BLOB *mac_key,
143 const uint8_t *hdr, size_t len,
145 uint8_t calc_md5_mac[16])
147 const size_t offset_end_of_sig = (HDR_SS_FIELD + 8);
148 uint8_t sequence_buf[8];
149 struct MD5Context md5_ctx;
152 * Firstly put the sequence number into the first 4 bytes.
153 * and zero out the next 4 bytes.
155 * We do this here, to avoid modifying the packet.
158 DEBUG(10,("smb_signing_md5: sequence number %u\n", seq_number ));
160 SIVAL(sequence_buf, 0, seq_number);
161 SIVAL(sequence_buf, 4, 0);
163 /* Calculate the 16 byte MAC - but don't alter the data in the
166 This makes for a bit of fussing about, but it's not too bad.
170 /* intialise with the key */
171 MD5Update(&md5_ctx, mac_key->data, mac_key->length);
173 /* copy in the first bit of the SMB header */
174 MD5Update(&md5_ctx, hdr, HDR_SS_FIELD);
176 /* copy in the sequence number, instead of the signature */
177 MD5Update(&md5_ctx, sequence_buf, sizeof(sequence_buf));
179 /* copy in the rest of the packet in, skipping the signature */
180 MD5Update(&md5_ctx, hdr + offset_end_of_sig,
181 len - (offset_end_of_sig));
183 /* calculate the MD5 sig */
184 MD5Final(calc_md5_mac, &md5_ctx);
187 uint32_t smb_signing_next_seqnum(struct smb_signing_state *si, bool oneway)
191 if (si->mac_key.length == 0) {
205 void smb_signing_cancel_reply(struct smb_signing_state *si, bool oneway)
207 if (si->mac_key.length == 0) {
218 void smb_signing_sign_pdu(struct smb_signing_state *si,
219 uint8_t *outbuf, uint32_t seqnum)
221 uint8_t calc_md5_mac[16];
224 uint8_t *outhdr = outbuf + NBT_HDR_SIZE;
225 size_t len = smb_len_nbt(outbuf);
227 if (si->mac_key.length == 0) {
228 if (!si->negotiated) {
233 /* JRA Paranioa test - we should be able to get rid of this... */
234 if (len < (HDR_SS_FIELD + 8)) {
235 DEBUG(1,("smb_signing_sign_pdu: Logic error. "
236 "Can't check signature on short packet! smb_len = %u\n",
241 com = SVAL(outhdr, HDR_COM);
242 flags = SVAL(outhdr, HDR_FLG);
244 if (!(flags & FLAG_REPLY)) {
245 uint16_t flags2 = SVAL(outhdr, HDR_FLG2);
247 * If this is a request, specify what is
248 * supported or required by the client
250 if (si->negotiated && si->desired) {
251 flags2 |= FLAGS2_SMB_SECURITY_SIGNATURES;
253 if (si->negotiated && si->mandatory) {
254 flags2 |= FLAGS2_SMB_SECURITY_SIGNATURES_REQUIRED;
256 SSVAL(outhdr, HDR_FLG2, flags2);
259 if (si->mac_key.length == 0) {
260 /* I wonder what BSRSPYL stands for - but this is what MS
262 if (com == SMBsesssetupX) {
263 memcpy(calc_md5_mac, "BSRSPYL ", 8);
265 memset(calc_md5_mac, 0, 8);
268 smb_signing_md5(&si->mac_key, outhdr, len,
269 seqnum, calc_md5_mac);
272 DEBUG(10, ("smb_signing_sign_pdu: sent SMB signature of\n"));
273 dump_data(10, calc_md5_mac, 8);
275 memcpy(&outhdr[HDR_SS_FIELD], calc_md5_mac, 8);
277 /* outhdr[HDR_SS_FIELD+2]=0;
278 Uncomment this to test if the remote server actually verifies signatures...*/
281 bool smb_signing_check_pdu(struct smb_signing_state *si,
282 const uint8_t *inbuf, uint32_t seqnum)
285 uint8_t calc_md5_mac[16];
286 const uint8_t *reply_sent_mac;
287 const uint8_t *inhdr = inbuf + NBT_HDR_SIZE;
288 size_t len = smb_len_nbt(inbuf);
290 if (si->mac_key.length == 0) {
294 if (len < (HDR_SS_FIELD + 8)) {
295 DEBUG(1,("smb_signing_check_pdu: Can't check signature "
296 "on short packet! smb_len = %u\n",
301 smb_signing_md5(&si->mac_key, inhdr, len,
302 seqnum, calc_md5_mac);
304 reply_sent_mac = &inhdr[HDR_SS_FIELD];
305 good = (memcmp(reply_sent_mac, calc_md5_mac, 8) == 0);
309 const int sign_range = 5;
311 DEBUG(5, ("smb_signing_check_pdu: BAD SIG: wanted SMB signature of\n"));
312 dump_data(5, calc_md5_mac, 8);
314 DEBUG(5, ("smb_signing_check_pdu: BAD SIG: got SMB signature of\n"));
315 dump_data(5, reply_sent_mac, 8);
317 for (i = -sign_range; i < sign_range; i++) {
318 smb_signing_md5(&si->mac_key, inhdr, len,
319 seqnum+i, calc_md5_mac);
320 if (memcmp(reply_sent_mac, calc_md5_mac, 8) == 0) {
321 DEBUG(0,("smb_signing_check_pdu: "
322 "out of seq. seq num %u matches. "
323 "We were expecting seq %u\n",
324 (unsigned int)seqnum+i,
325 (unsigned int)seqnum));
330 DEBUG(10, ("smb_signing_check_pdu: seq %u: "
331 "got good SMB signature of\n",
332 (unsigned int)seqnum));
333 dump_data(10, reply_sent_mac, 8);
336 return smb_signing_good(si, good, seqnum);
339 bool smb_signing_activate(struct smb_signing_state *si,
340 const DATA_BLOB user_session_key,
341 const DATA_BLOB response)
346 if (!user_session_key.length) {
350 if (!si->negotiated) {
358 if (si->mac_key.length > 0) {
362 smb_signing_reset_info(si);
364 len = response.length + user_session_key.length;
366 si->mac_key.data = (uint8_t *)si->alloc_fn(si->mem_ctx, len);
367 if (si->mac_key.data == NULL) {
371 si->mac_key.data = (uint8_t *)talloc_size(si, len);
372 if (si->mac_key.data == NULL) {
376 si->mac_key.length = len;
379 memcpy(&si->mac_key.data[ofs], user_session_key.data, user_session_key.length);
381 DEBUG(10, ("smb_signing_activate: user_session_key\n"));
382 dump_data(10, user_session_key.data, user_session_key.length);
384 if (response.length) {
385 ofs = user_session_key.length;
386 memcpy(&si->mac_key.data[ofs], response.data, response.length);
387 DEBUG(10, ("smb_signing_activate: response_data\n"));
388 dump_data(10, response.data, response.length);
390 DEBUG(10, ("smb_signing_activate: NULL response_data\n"));
393 dump_data_pw("smb_signing_activate: mac key is:\n",
394 si->mac_key.data, si->mac_key.length);
396 /* Initialise the sequence number */
402 bool smb_signing_is_active(struct smb_signing_state *si)
407 bool smb_signing_is_allowed(struct smb_signing_state *si)
412 bool smb_signing_is_mandatory(struct smb_signing_state *si)
414 return si->mandatory;
417 bool smb_signing_set_negotiated(struct smb_signing_state *si,
418 bool allowed, bool mandatory)
424 if (!si->allowed && mandatory) {
428 if (si->mandatory && !allowed) {
433 si->negotiated = true;
438 si->negotiated = true;
443 si->negotiated = false;
447 if (si->desired && allowed) {
448 si->negotiated = true;
452 si->negotiated = false;
456 bool smb_signing_is_negotiated(struct smb_signing_state *si)
458 return si->negotiated;