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authorDan Harkins <dharkins@lounge.org>2012-02-11 10:46:30 (GMT)
committerJouni Malinen <j@w1.fi>2012-02-11 10:46:30 (GMT)
commit5ea93947ca67ba83529798b806a15b247cdb2e93 (patch)
treef89dfd7a27ccbe3ec19d144850fda067c6ccb0e1 /src/eap_server/eap_server_pwd.c
parent27c9d333d4bfab2b3ac377e5a7920e14a0fc6fe9 (diff)
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EAP-pwd: Add support for fragmentation
Signed-hostap: Dan Harkins <dharkins@lounge.org>
Diffstat (limited to 'src/eap_server/eap_server_pwd.c')
-rw-r--r--src/eap_server/eap_server_pwd.c311
1 files changed, 248 insertions, 63 deletions
diff --git a/src/eap_server/eap_server_pwd.c b/src/eap_server/eap_server_pwd.c
index 4c6f4d1..8235e7d 100644
--- a/src/eap_server/eap_server_pwd.c
+++ b/src/eap_server/eap_server_pwd.c
@@ -33,6 +33,12 @@ struct eap_pwd_data {
u16 group_num;
EAP_PWD_group *grp;
+ struct wpabuf *inbuf;
+ size_t in_frag_pos;
+ struct wpabuf *outbuf;
+ size_t out_frag_pos;
+ size_t mtu;
+
BIGNUM *k;
BIGNUM *private_value;
BIGNUM *peer_scalar;
@@ -120,6 +126,10 @@ static void * eap_pwd_init(struct eap_sm *sm)
return NULL;
}
+ data->in_frag_pos = data->out_frag_pos = 0;
+ data->inbuf = data->outbuf = NULL;
+ data->mtu = 1020; /* default from RFC 5931, make it configurable! */
+
return data;
}
@@ -149,44 +159,48 @@ static void eap_pwd_reset(struct eap_sm *sm, void *priv)
}
-static struct wpabuf *
-eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
+static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
+ u8 id)
{
- struct wpabuf *req;
-
wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
- req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
- 1 + sizeof(struct eap_pwd_id) +
- data->id_server_len,
- EAP_CODE_REQUEST, id);
- if (req == NULL) {
+ /*
+ * if we're fragmenting then we already have an id request, just return
+ */
+ if (data->out_frag_pos)
+ return;
+
+ data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
+ data->id_server_len);
+ if (data->outbuf == NULL) {
eap_pwd_state(data, FAILURE);
- return NULL;
+ return;
}
/* an lfsr is good enough to generate unpredictable tokens */
data->token = os_random();
- wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
- wpabuf_put_be16(req, data->group_num);
- wpabuf_put_u8(req, EAP_PWD_DEFAULT_RAND_FUNC);
- wpabuf_put_u8(req, EAP_PWD_DEFAULT_PRF);
- wpabuf_put_data(req, &data->token, sizeof(data->token));
- wpabuf_put_u8(req, EAP_PWD_PREP_NONE);
- wpabuf_put_data(req, data->id_server, data->id_server_len);
-
- return req;
+ wpabuf_put_be16(data->outbuf, data->group_num);
+ wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
+ wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
+ wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
+ wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
+ wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
}
-static struct wpabuf *
-eap_pwd_build_commit_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
+static void eap_pwd_build_commit_req(struct eap_sm *sm,
+ struct eap_pwd_data *data, u8 id)
{
- struct wpabuf *req = NULL;
BIGNUM *mask = NULL, *x = NULL, *y = NULL;
u8 *scalar = NULL, *element = NULL;
u16 offset;
wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
+ /*
+ * if we're fragmenting then we already have an commit request, just
+ * return
+ */
+ if (data->out_frag_pos)
+ return;
if (((data->private_value = BN_new()) == NULL) ||
((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
@@ -256,34 +270,29 @@ eap_pwd_build_commit_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
- req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
- 1 + (2 * BN_num_bytes(data->grp->prime)) +
- BN_num_bytes(data->grp->order),
- EAP_CODE_REQUEST, id);
- if (req == NULL)
+ data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
+ BN_num_bytes(data->grp->order));
+ if (data->outbuf == NULL)
goto fin;
- wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
/* We send the element as (x,y) followed by the scalar */
- wpabuf_put_data(req, element, (2 * BN_num_bytes(data->grp->prime)));
- wpabuf_put_data(req, scalar, BN_num_bytes(data->grp->order));
+ wpabuf_put_data(data->outbuf, element,
+ 2 * BN_num_bytes(data->grp->prime));
+ wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
fin:
os_free(scalar);
os_free(element);
BN_free(x);
BN_free(y);
- if (req == NULL)
+ if (data->outbuf == NULL)
eap_pwd_state(data, FAILURE);
-
- return req;
}
-static struct wpabuf *
-eap_pwd_build_confirm_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
+static void eap_pwd_build_confirm_req(struct eap_sm *sm,
+ struct eap_pwd_data *data, u8 id)
{
- struct wpabuf *req = NULL;
BIGNUM *x = NULL, *y = NULL;
HMAC_CTX ctx;
u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr;
@@ -291,6 +300,12 @@ eap_pwd_build_confirm_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
int offset;
wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
+ /*
+ * if we're fragmenting then we already have an confirm request, just
+ * return
+ */
+ if (data->out_frag_pos)
+ return;
/* Each component of the cruft will be at most as big as the prime */
if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
@@ -383,23 +398,20 @@ eap_pwd_build_confirm_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
H_Final(&ctx, conf);
os_memcpy(data->my_confirm, conf, SHA256_DIGEST_LENGTH);
- req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
- 1 + SHA256_DIGEST_LENGTH,
- EAP_CODE_REQUEST, id);
- if (req == NULL)
+ data->outbuf = wpabuf_alloc(SHA256_DIGEST_LENGTH);
+ if (data->outbuf == NULL)
goto fin;
- wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
- wpabuf_put_data(req, conf, SHA256_DIGEST_LENGTH);
+ wpabuf_put_data(data->outbuf, conf, SHA256_DIGEST_LENGTH);
fin:
os_free(cruft);
BN_free(x);
BN_free(y);
- if (req == NULL)
+ if (data->outbuf == NULL)
eap_pwd_state(data, FAILURE);
- return req;
+ return;
}
@@ -407,21 +419,119 @@ static struct wpabuf *
eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
{
struct eap_pwd_data *data = priv;
+ struct wpabuf *req;
+ u8 lm_exch;
+ const u8 *buf;
+ u16 totlen = 0;
+ size_t len;
+
+ /*
+ * if we're buffering response fragments then just ACK
+ */
+ if (data->in_frag_pos) {
+ wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
+ req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
+ EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
+ if (req == NULL) {
+ eap_pwd_state(data, FAILURE);
+ return NULL;
+ }
+ switch (data->state) {
+ case PWD_ID_Req:
+ wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
+ break;
+ case PWD_Commit_Req:
+ wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
+ break;
+ case PWD_Confirm_Req:
+ wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
+ break;
+ default:
+ eap_pwd_state(data, FAILURE); /* just to be sure */
+ wpabuf_free(req);
+ return NULL;
+ }
+ return req;
+ }
+ /*
+ * build the data portion of a request
+ */
switch (data->state) {
- case PWD_ID_Req:
- return eap_pwd_build_id_req(sm, data, id);
- case PWD_Commit_Req:
- return eap_pwd_build_commit_req(sm, data, id);
- case PWD_Confirm_Req:
- return eap_pwd_build_confirm_req(sm, data, id);
- default:
+ case PWD_ID_Req:
+ eap_pwd_build_id_req(sm, data, id);
+ lm_exch = EAP_PWD_OPCODE_ID_EXCH;
+ break;
+ case PWD_Commit_Req:
+ eap_pwd_build_commit_req(sm, data, id);
+ lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
+ break;
+ case PWD_Confirm_Req:
+ eap_pwd_build_confirm_req(sm, data, id);
+ lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
+ break;
+ default:
wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
data->state);
+ eap_pwd_state(data, FAILURE);
+ lm_exch = 0; /* hush now, sweet compiler */
break;
}
- return NULL;
+ if (data->state == FAILURE)
+ return NULL;
+
+ /*
+ * determine whether that data needs to be fragmented
+ */
+ len = wpabuf_len(data->outbuf) - data->out_frag_pos;
+ if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
+ len = data->mtu - EAP_PWD_HDR_SIZE;
+ EAP_PWD_SET_MORE_BIT(lm_exch);
+ /*
+ * if this is the first fragment, need to set the M bit
+ * and add the total length to the eap_pwd_hdr
+ */
+ if (data->out_frag_pos == 0) {
+ EAP_PWD_SET_LENGTH_BIT(lm_exch);
+ totlen = wpabuf_len(data->outbuf) +
+ EAP_PWD_HDR_SIZE + sizeof(u16);
+ len -= sizeof(u16);
+ wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
+ "total length = %d", totlen);
+ }
+ wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
+ (int) len);
+ }
+
+ /*
+ * alloc an eap request and populate it with the data
+ */
+ req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
+ EAP_PWD_HDR_SIZE + len +
+ (totlen ? sizeof(u16) : 0),
+ EAP_CODE_REQUEST, id);
+ if (req == NULL) {
+ eap_pwd_state(data, FAILURE);
+ return NULL;
+ }
+
+ wpabuf_put_u8(req, lm_exch);
+ if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
+ wpabuf_put_be16(req, totlen);
+
+ buf = wpabuf_head_u8(data->outbuf);
+ wpabuf_put_data(req, buf + data->out_frag_pos, len);
+ data->out_frag_pos += len;
+ /*
+ * either not fragged or last fragment, either way free up the data
+ */
+ if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
+ wpabuf_free(data->outbuf);
+ data->out_frag_pos = 0;
+ }
+
+ return req;
}
@@ -438,17 +548,19 @@ static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
return TRUE;
}
- wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: opcode=%d", *pos);
+ wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
+ EAP_PWD_GET_EXCHANGE(*pos), (int) len);
- if (data->state == PWD_ID_Req && *pos == EAP_PWD_OPCODE_ID_EXCH)
+ if (data->state == PWD_ID_Req &&
+ ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
return FALSE;
if (data->state == PWD_Commit_Req &&
- *pos == EAP_PWD_OPCODE_COMMIT_EXCH)
+ ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
return FALSE;
if (data->state == PWD_Confirm_Req &&
- *pos == EAP_PWD_OPCODE_CONFIRM_EXCH)
+ ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
return FALSE;
wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
@@ -747,7 +859,8 @@ static void eap_pwd_process(struct eap_sm *sm, void *priv,
struct eap_pwd_data *data = priv;
const u8 *pos;
size_t len;
- u8 exch;
+ u8 lm_exch;
+ u16 tot_len;
pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
if ((pos == NULL) || (len < 1)) {
@@ -757,18 +870,90 @@ static void eap_pwd_process(struct eap_sm *sm, void *priv,
return;
}
- exch = *pos & 0x3f;
- switch (exch) {
+ lm_exch = *pos;
+ pos++; /* skip over the bits and the exch */
+ len--;
+
+ /*
+ * if we're fragmenting then this should be an ACK with no data,
+ * just return and continue fragmenting in the "build" section above
+ */
+ if (data->out_frag_pos) {
+ if (len > 1)
+ wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
+ "Fragmenting but not an ACK");
+ else
+ wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
+ "peer");
+ return;
+ }
+ /*
+ * if we're receiving fragmented packets then we need to buffer...
+ *
+ * the first fragment has a total length
+ */
+ if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
+ tot_len = WPA_GET_BE16(pos);
+ wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
+ "length = %d", tot_len);
+ data->inbuf = wpabuf_alloc(tot_len);
+ if (data->inbuf == NULL) {
+ wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
+ "buffer fragments!");
+ return;
+ }
+ pos += sizeof(u16);
+ len -= sizeof(u16);
+ }
+ /*
+ * the first and all intermediate fragments have the M bit set
+ */
+ if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
+ if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
+ wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
+ "attack detected! (%d+%d > %d)",
+ (int) data->in_frag_pos, (int) len,
+ (int) wpabuf_size(data->inbuf));
+ eap_pwd_state(data, FAILURE);
+ return;
+ }
+ wpabuf_put_data(data->inbuf, pos, len);
+ data->in_frag_pos += len;
+ wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
+ (int) len);
+ return;
+ }
+ /*
+ * last fragment won't have the M bit set (but we're obviously
+ * buffering fragments so that's how we know it's the last)
+ */
+ if (data->in_frag_pos) {
+ wpabuf_put_data(data->inbuf, pos, len);
+ data->in_frag_pos += len;
+ pos = wpabuf_head_u8(data->inbuf);
+ len = data->in_frag_pos;
+ wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
+ (int) len);
+ }
+ switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
case EAP_PWD_OPCODE_ID_EXCH:
- eap_pwd_process_id_resp(sm, data, pos + 1, len - 1);
+ eap_pwd_process_id_resp(sm, data, pos, len);
break;
case EAP_PWD_OPCODE_COMMIT_EXCH:
- eap_pwd_process_commit_resp(sm, data, pos + 1, len - 1);
+ eap_pwd_process_commit_resp(sm, data, pos, len);
break;
- case EAP_PWD_OPCODE_CONFIRM_EXCH:
- eap_pwd_process_confirm_resp(sm, data, pos + 1, len - 1);
+ case EAP_PWD_OPCODE_CONFIRM_EXCH:
+ eap_pwd_process_confirm_resp(sm, data, pos, len);
break;
}
+ /*
+ * if we had been buffering fragments, here's a great place
+ * to clean up
+ */
+ if (data->in_frag_pos) {
+ wpabuf_free(data->inbuf);
+ data->in_frag_pos = 0;
+ }
}